WorldWideScience

Sample records for prey genetics demography

  1. Demography and genetic structure of a recovering grizzly bear population

    Science.gov (United States)

    Kendall, K.C.; Stetz, J.B.; Boulanger, J.; Macleod, A.C.; Paetkau, David; White, Gary C.

    2009-01-01

    Grizzly bears (brown bears; Ursus arctos) are imperiled in the southern extent of their range worldwide. The threatened population in northwestern Montana, USA, has been managed for recovery since 1975; yet, no rigorous data were available to monitor program success. We used data from a large noninvasive genetic sampling effort conducted in 2004 and 33 years of physical captures to assess abundance, distribution, and genetic health of this population. We combined data from our 3 sampling methods (hair trap, bear rub, and physical capture) to construct individual bear encounter histories for use in Huggins-Pledger closed mark-recapture models. Our population estimate, N?? = 765 (95% CI = 715-831) was more than double the existing estimate derived from sightings of females with young. Based on our results, the estimated known, human-caused mortality rate in 2004 was 4.6% (95% CI = 4.2-4.9%), slightly above the 4% considered sustainable; however, the high proportion of female mortalities raises concern. We used location data from telemetry, confirmed sightings, and genetic sampling to estimate occupied habitat. We found that grizzly bears occupied 33,480 km2 in the Northern Continental Divide Ecosystem (NCDE) during 1994-2007, including 10,340 km beyond the Recovery Zone. We used factorial correspondence analysis to identify potential barriers to gene flow within this population. Our results suggested that genetic interchange recently increased in areas with low gene flow in the past; however, we also detected evidence of incipient fragmentation across the major transportation corridor in this ecosystem. Our results suggest that the NCDE population is faring better than previously thought, and they highlight the need for a more rigorous monitoring program.

  2. Demography, genetic diversity, and population relationships among Argentinean Mapuche Indians

    Directory of Open Access Journals (Sweden)

    Alicia S. Goicoechea

    2000-09-01

    Full Text Available Fertility, mortality and migration data from four Mapuche Indian communities located along a 215-km NE-SW linear area in the Province of Río Negro, Argentina, were collated with genetic information furnished by nine blood group systems and by mtDNA haplogroups. The demographic and genetic data indicated a clear dichotomy, which split the four populations into two groups of two. Differing degrees of non-Indian exchanges was probably the main determining factor for this separation. Total genetic variability was very similar in all groups, and the interpopulational variability accounted for only 10% of the total variability. A low prevalence of the Diego(a antigen among the Mapuche was confirmed. The fact that significant genetic heterogeneity and population clusters were found in such a small territorial region attests to the sensitivity of demographic and genetic approaches in unraveling human history.Dados relativos a fertilidade, mortalidade e migração de quatro comunidades de índios Mapuche localizadas em uma área linear na direção nordeste-sudoeste com 215 km de extensão na Província de Rio Negro, Argentina, foram associados com a informação genética fornecida por nove sistemas de grupos sangüíneos e os haplogrupos do DNA mitocondrial. Ambos os tipos de informação apontam claramente para uma dicotomia, as quatro populações sendo divididas em grupos de duas. O principal fator responsável por esta separação é provavelmente graus diferentes de mistura com não-índios. A variabilidade genética total foi muito similar em todos os grupos, aquela entre populações sendo de apenas 10% deste valor. Foi confirmada a baixa prevalência do antígeno Diego(a entre os Mapuche. O fato de que heterogeneidade genética significativa e conjuntos populacionais diversos foram observados em uma região territorial tão pequena demonstra a sensibilidade dos enfoques demográfico e genético no esclarecimento da história humana.

  3. Linking anti-predator behaviour to prey demography reveals limited risk effects of an actively hunting large carnivore.

    Science.gov (United States)

    Middleton, Arthur D; Kauffman, Matthew J; McWhirter, Douglas E; Jimenez, Michael D; Cook, Rachel C; Cook, John G; Albeke, Shannon E; Sawyer, Hall; White, P J

    2013-08-01

    Ecological theory predicts that the diffuse risk cues generated by wide-ranging, active predators should induce prey behavioural responses but not major, population- or community-level consequences. We evaluated the non-consumptive effects (NCEs) of an active predator, the grey wolf (Canis lupus), by simultaneously tracking wolves and the behaviour, body fat, and pregnancy of elk (Cervus elaphus), their primary prey in the Greater Yellowstone Ecosystem. When wolves approached within 1 km, elk increased their rates of movement, displacement and vigilance. Even in high-risk areas, however, these encounters occurred only once every 9 days. Ultimately, despite 20-fold variation in the frequency of encounters between wolves and individual elk, the risk of predation was not associated with elk body fat or pregnancy. Our findings suggest that the ecological consequences of actively hunting large carnivores, such as the wolf, are more likely transmitted by consumptive effects on prey survival than NCEs on prey behaviour. © 2013 John Wiley & Sons Ltd/CNRS.

  4. A general population genetic framework for antagonistic selection that accounts for demography and recurrent mutation.

    Science.gov (United States)

    Connallon, Tim; Clark, Andrew G

    2012-04-01

    Antagonistic selection--where alleles at a locus have opposing effects on male and female fitness ("sexual antagonism") or between components of fitness ("antagonistic pleiotropy")--might play an important role in maintaining population genetic variation and in driving phylogenetic and genomic patterns of sexual dimorphism and life-history evolution. While prior theory has thoroughly characterized the conditions necessary for antagonistic balancing selection to operate, we currently know little about the evolutionary interactions between antagonistic selection, recurrent mutation, and genetic drift, which should collectively shape empirical patterns of genetic variation. To fill this void, we developed and analyzed a series of population genetic models that simultaneously incorporate these processes. Our models identify two general properties of antagonistically selected loci. First, antagonistic selection inflates heterozygosity and fitness variance across a broad parameter range--a result that applies to alleles maintained by balancing selection and by recurrent mutation. Second, effective population size and genetic drift profoundly affect the statistical frequency distributions of antagonistically selected alleles. The "efficacy" of antagonistic selection (i.e., its tendency to dominate over genetic drift) is extremely weak relative to classical models, such as directional selection and overdominance. Alleles meeting traditional criteria for strong selection (N(e)s > 1, where N(e) is the effective population size, and s is a selection coefficient for a given sex or fitness component) may nevertheless evolve as if neutral. The effects of mutation and demography may generate population differences in overall levels of antagonistic fitness variation, as well as molecular population genetic signatures of balancing selection.

  5. Confronting the stigma of eugenics: genetics, demography and the problems of population.

    Science.gov (United States)

    Ramsden, Edmund

    2009-12-01

    Building upon the work of Thomas Gieryn and Erving Goffman, this paper will explore how the concepts of stigma and boundary work can be usefully applied to history of population science. Having been closely aligned to eugenics in the early 20th century, from the 1930s both demographers and geneticists began to establish a boundary between their own disciplines and eugenic ideology. The eugenics movement responded to this process of stigmatization. Through strategies defined by Goffman as 'disclosure' and 'concealment', stigma was managed, and a limited space for eugenics was retained in science and policy. Yet by the 1960s, a revitalized eugenics movement was bringing leading social and biological scientists together through the study of the genetic demography of characteristics such as intelligence. The success of this programme of 'stigma transformation' resulted from its ability to allow geneticists and demographers to conceive of eugenic improvement in ways that seemed consistent with the ideals of individuality, diversity and liberty. In doing so, it provided them with an alternative, and a challenge, to more radical and controversial programmes to realize an optimal genotype and population. The processes of stigma attribution and management are, however, ongoing, and since the rise of the nature-nurture controversy in the 1970s, the use of eugenics as a 'stigma symbol' has prevailed.

  6. Eugenics from the New Deal to the Great Society: genetics, demography and population quality.

    Science.gov (United States)

    Ramsden, Edmund

    2008-12-01

    The relationship between biological and social scientists as regards the study of human traits and behavior has often been perceived in terms of mutual distrust, even antipathy. In the interwar period, population study seemed an area that might allow for closer relations between them-united as they were by a concern to improve the eugenic quality of populations. Yet these relations were in tension: by the early post-war era, social demographers were denigrating the contributions of biologists to the study of population problems as embodying the elitist ideology of eugenics. In response to this loss of credibility, the eugenics movement pursued a simultaneous program of withdrawal and expansion: its leaders helped focus concern with biological quality onto the developing field of medical genetics, while at the same moment, extended their scope to improving the social quality of populations through birth control policies, guided by demography. While this approach maintained boundaries between the social and the biological, in the 1960s, a revitalized American Eugenics Society helped reunite leading demographers and geneticists. This paper will assess the reasons for this period of influence for eugenics, and explore its implications for the social and biological study of human populations.

  7. The Effects of Predator Evolution and Genetic Variation on Predator-Prey Population-Level Dynamics.

    Science.gov (United States)

    Cortez, Michael H; Patel, Swati

    2017-07-01

    This paper explores how predator evolution and the magnitude of predator genetic variation alter the population-level dynamics of predator-prey systems. We do this by analyzing a general eco-evolutionary predator-prey model using four methods: Method 1 identifies how eco-evolutionary feedbacks alter system stability in the fast and slow evolution limits; Method 2 identifies how the amount of standing predator genetic variation alters system stability; Method 3 identifies how the phase lags in predator-prey cycles depend on the amount of genetic variation; and Method 4 determines conditions for different cycle shapes in the fast and slow evolution limits using geometric singular perturbation theory. With these four methods, we identify the conditions under which predator evolution alters system stability and shapes of predator-prey cycles, and how those effect depend on the amount of genetic variation in the predator population. We discuss the advantages and disadvantages of each method and the relations between the four methods. This work shows how the four methods can be used in tandem to make general predictions about eco-evolutionary dynamics and feedbacks.

  8. Evolutionary Demography

    DEFF Research Database (Denmark)

    Levitis, Daniel

    2015-01-01

    of biological and cultural evolution. Demographic variation within and among human populations is influenced by our biology, and therefore by natural selection and our evolutionary background. Demographic methods are necessary for studying populations of other species, and for quantifying evolutionary fitness......Demography is the quantitative study of population processes, while evolution is a population process that influences all aspects of biological organisms, including their demography. Demographic traits common to all human populations are the products of biological evolution or the interaction...

  9. Urban park characteristics, genetic variation, and historical demography of white-footed mouse (Peromyscus leucopus populations in New York City

    Directory of Open Access Journals (Sweden)

    Jason Munshi-South

    2014-03-01

    Full Text Available Severe fragmentation is a typical fate of native remnant habitats in cities, and urban wildlife with limited dispersal ability are predicted to lose genetic variation in isolated urban patches. However, little information exists on the characteristics of urban green spaces required to conserve genetic variation. In this study, we examine whether isolation in New York City (NYC parks results in genetic bottlenecks in white-footed mice (Peromyscus leucopus, and test the hypotheses that park size and time since isolation are associated with genetic variability using nonlinear regression and information-theoretic model selection. White-footed mice have previously been documented to exhibit male-biased dispersal, which may create disparities in genetic variation between males and females in urban parks. We use genotypes of 18 neutral microsatellite data and four different statistical tests to assess this prediction. Given that sex-biased dispersal may create disparities between population genetic patterns inferred from bi- vs. uni-parentally inherited markers, we also sequenced a 324 bp segment of the mitochondrial D-loop for independent inferences of historical demography in urban P. leucopus. We report that isolation in urban parks does not necessarily result in genetic bottlenecks; only three out of 14 populations in NYC parks exhibited a signature of a recent bottleneck at 18 neutral microsatellite loci. Mouse populations in larger urban parks, or parks that have been isolated for shorter periods of time, also do not generally contain greater genetic variation than populations in smaller parks. These results suggest that even small networks of green spaces may be sufficient to maintain the evolutionary potential of native species with certain characteristics. We also found that isolation in urban parks results in weak to nonexistent sex-biased dispersal in a species known to exhibit male-biased dispersal in less fragmented environments. In

  10. High functional diversity in Mycobacterium tuberculosis driven by genetic drift and human demography.

    Directory of Open Access Journals (Sweden)

    Ruth Hershberg

    2008-12-01

    Full Text Available Mycobacterium tuberculosis infects one third of the human world population and kills someone every 15 seconds. For more than a century, scientists and clinicians have been distinguishing between the human- and animal-adapted members of the M. tuberculosis complex (MTBC. However, all human-adapted strains of MTBC have traditionally been considered to be essentially identical. We surveyed sequence diversity within a global collection of strains belonging to MTBC using seven megabase pairs of DNA sequence data. We show that the members of MTBC affecting humans are more genetically diverse than generally assumed, and that this diversity can be linked to human demographic and migratory events. We further demonstrate that these organisms are under extremely reduced purifying selection and that, as a result of increased genetic drift, much of this genetic diversity is likely to have functional consequences. Our findings suggest that the current increases in human population, urbanization, and global travel, combined with the population genetic characteristics of M. tuberculosis described here, could contribute to the emergence and spread of drug-resistant tuberculosis.

  11. Demography and genetic diversity of the Mexican black iguana Ctenosaura pectinata

    OpenAIRE

    Aguirre-Hlidalgo, Victor

    2008-01-01

    The hunting of the black iguana (Ctenosaura pectinata) in some regions of Mexico constitutes an acute problem because mature, gravid females arc killed and eaten just before they lay their eggs. This practice thus impacts both the survival of adults and the otherwise imminent recruitment of new individuals to the population. The objective of this project was to compare the demographic behaviour and the genetic variability of two population of the black iguana, one protected and...

  12. Genetic diversity and population demography of the Chinese crocodile lizard (Shinisaurus crocodilurus in China.

    Directory of Open Access Journals (Sweden)

    Huayuan Huang

    Full Text Available The Chinese crocodile lizard Shinisaurus crocodilurus is a critically endangered species, listed in Appendix II of CITES. Its populations and habitat in China have undergone significant changes in recent years. Understanding the genetic variability and phylogeography of this species is very important for successful conservation. In this study, samples were taken from 11 wild ponds and two captive populations in China. We sequenced mitochondrial CYTB, partial ND6, and partial tRNA-Glu and genotyped 10 microsatellite loci. Our analyses of these data showed low genetic variability, no strong isolation caused by distance, and a lack of a phylogeographic structure in this species. Based on our results, the basal divergence between two clades of S. crocodilurus in China may have been caused by the formation of the Pearl River system. We found a population expansion in one of these clades. Microsatellite analysis indicated the presence of three clusters, separated by significant genetic differences. We found that most individuals in the two captive populations were from the Luokeng (Guangdong and Guangxi wild source populations, respectively.

  13. Anthropology and demography

    Directory of Open Access Journals (Sweden)

    Bošković Aleksandar

    2013-01-01

    little more information we would know a great deal more such as household and family composition, economic organization, social problems, and something of the political structure. It we knew the schedules for populations in general and could correlate the schedules with the causes, genetic or environmental, that produce them, we would know a great deal about the possible range of human social structure" (Howell, 1986: 219. In the second part of the paper, the author discusses several examples of interplay between anthropology and demography. One of them is Patrick Heady′s study of the shift in ritual patterns, which combines elements of some "classical" anthropological topics (Mauss’s theory of gift exchange and Lévi-Strauss′s concept of kinship with his own field research in the Carnian Alps. "By marrying and raising children, parents participate in a system of gift-exchange in which the gifts in question are human lives, and the parties to the exchange are the kinship groups recognized in the society concerned. Fertility reflects the attitudes of prospective parents to their place in the existing system of reproductive exchange, and the relationships of cooperation and authority which it implies - as well as their confidence in the system’s continuing viability. It is shown that this view is compatible with earlier ideas about self-regulating population systems - and that changing economic circumstances are an important source of discrepancy between existing exchange systems and the attitudes and expectations of prospective parents" (Heady, 2007: 465. The paper concludes with the discussion of the directions in which relationship between these two disciplines can proceed. Some of the epistemological issues are mentioned, as well as a need to apply different theoretical perspectives to better understand demographic behavior (especially in Europe and to better understand certain cultural components that shape this behavior. In order to achieve this, most of the

  14. Crossroads of demography

    Directory of Open Access Journals (Sweden)

    Devedžić Mirjana

    2013-01-01

    Full Text Available This paper is dedicated to the 50th anniversary of the Stanovništvo (Population journal, launched by the Center for demographic research in Belgrade in 1963. The anniversary is an opportunity to reflect on developments and trends in demography as a discipline, thus the paper points out certain specifics of these developments. The specifics discussed mirror the author's choice, which was guided primarily by the criterion of interestingness, but also by the intention to make a survey. Hence points about the development of demography are backed by insights made by a number of other demographers. The major source of references were papers and speeches given on similar occasions - anniversaries of journals, anniversaries of associations of demographers, as well as special issues of journals dedicated to theory and methodology. Certain points are also made based on other sources of reference. The major part of the paper is related to transformations of demography, which has started as a predominantly formal discipline and has developed into a social and interdisciplinary field. Topical and methodological expansion of demography induces mixed reactions among demographers. Ones welcome its diversification, whereas others see such changes as signs of abandoning the essence of demography. This makes it harder and harder to define the area of demographic research. Changes in demography are mostly studied from the standpoint of polarized dimensions: quantitative-qualitative, macro-micro, and, in the context of diversification, formal demography vs. population studies. Another important segment of development trends in demography is that of improving its vocabulary, which is affected by other fields related to demography. Terminological changes are also related to the specification of certain branches and subfields of demography. For instance, anthropological and spatial demography have roots in earlier development phases of demography. Still, these terms

  15. Predicting the genetic consequences of future climate change: The power of coupling spatial demography, the coalescent, and historical landscape changes.

    Science.gov (United States)

    Brown, Jason L; Weber, Jennifer J; Alvarado-Serrano, Diego F; Hickerson, Michael J; Franks, Steven J; Carnaval, Ana C

    2016-01-01

    Climate change is a widely accepted threat to biodiversity. Species distribution models (SDMs) are used to forecast whether and how species distributions may track these changes. Yet, SDMs generally fail to account for genetic and demographic processes, limiting population-level inferences. We still do not understand how predicted environmental shifts will impact the spatial distribution of genetic diversity within taxa. We propose a novel method that predicts spatially explicit genetic and demographic landscapes of populations under future climatic conditions. We use carefully parameterized SDMs as estimates of the spatial distribution of suitable habitats and landscape dispersal permeability under present-day, past, and future conditions. We use empirical genetic data and approximate Bayesian computation to estimate unknown demographic parameters. Finally, we employ these parameters to simulate realistic and complex models of responses to future environmental shifts. We contrast parameterized models under current and future landscapes to quantify the expected magnitude of change. We implement this framework on neutral genetic data available from Penstemon deustus. Our results predict that future climate change will result in geographically widespread declines in genetic diversity in this species. The extent of reduction will heavily depend on the continuity of population networks and deme sizes. To our knowledge, this is the first study to provide spatially explicit predictions of within-species genetic diversity using climatic, demographic, and genetic data. Our approach accounts for climatic, geographic, and biological complexity. This framework is promising for understanding evolutionary consequences of climate change, and guiding conservation planning. © 2016 Botanical Society of America.

  16. Genes, Demography, and Life Span: The Contribution of Demographic Data in Genetic Studies on Aging and Longevity

    DEFF Research Database (Denmark)

    Yashin, AI; De Benedictis, G; Vaupel, JW

    1999-01-01

    In population studies on aging, the data on genetic markers are often collected for individuals from different age groups. The purpose of such studies is to identify, by comparison of the frequencies of selected genotypes, “longevity” or “frailty” genes in the oldest and in younger groups...... of individuals. To address questions about more-complicated aspects of genetic influence on longevity, additional information must be used. In this article, we show that the use of demographic information, together with data on genetic markers, allows us to calculate hazard rates, relative risks, and survival...... functions for respective genes or genotypes. New methods of combining genetic and demographic information are discussed. These methods are tested on simulated data and then are applied to the analysis of data on genetic markers for two haplogroups of human mtDNA. The approaches suggested in this article...

  17. Family and household demography

    NARCIS (Netherlands)

    Willekens, F.J.C.; Zeng, Yi

    2009-01-01

    Households are groups of people that co-reside and share some resources. Families are households of related individuals. Household and family demography is the study of these primary social groups or social units, and in particular of group membership and the relationships between members of the

  18. The anthropological demography of Europe

    Directory of Open Access Journals (Sweden)

    Inge Hutter

    2007-12-01

    Full Text Available This paper introduces a collection of related research studies on the anthropological demography of Europe. Anthropological demography is a specialty within demography that uses anthropological theory and methods to provide a better understanding of demographic phenomena in current and past populations. Its genesis and ongoing growth lies at the intersection of demography and socio-cultural anthropology and with their efforts to understand population processes: mainly fertility, migration, and mortality. Both disciplines share a common research subject, namely human populations, and they focus on mutually complementary aspects. The authors of this paper focus on the differences between the disciplines of anthropology and demography, the emergence of anthropological demography and its theoretical, methodological, and empirical aspects. In addition, they critically summarize the contributions that were presented in the first workshop of the Working Group on Anthropological Demography of Europe of the European Association for Population Studies, held in Rostock in Fall 2005 and reflect on how these papers add to the further development of anthropological demography in Europe, i.e. elaborating the epistemology of anthropological demography; applying additional theoretical perspectives to better understand demographic behaviour in Europe ; illustrating the way in which culture plays a role in case studies on European demographic behaviour; and emphasizing the need for a holistic approach to data collection and the added value of triangulating quantitative and qualitative analyses.

  19. Joint evolution of predator body size and prey-size preference.

    NARCIS (Netherlands)

    Troost, T.A.; Kooi, B.W.; Dieckmann, U.

    2007-01-01

    We studied the joint evolution of predator body size and prey-size preference based on dynamic energy budget theory. The predators' demography and their functional response are based on general eco-physiological principles involving the size of both predator and prey. While our model can account for

  20. Joint evolution of predator body size and prey-size preference

    NARCIS (Netherlands)

    Troost, Tineke; Kooi, Bob; Dieckmann, Ulf

    2007-01-01

    We studied the joint evolution of predator body size and prey-size preference based on dynamic energy budget theory. The predators’ demography and their functional response are based on general eco-physiological principles involving the size of both predator and prey. While our model can account

  1. Serbian demographers on demography

    Directory of Open Access Journals (Sweden)

    Rašević Mirjana

    2013-01-01

    Full Text Available Introduction: The objective of this paper is to collect the opinions of the leading demographers in Serbia on four significant matters. The matters are: development, state and future of demography, the successfulness of researchers in this scientific discipline, improvement of the Stanovništvo journal, as well as the population priority of our society and range of population policies. Method: A qualitative interview was chosen as the instrument for data collection. Namely, a structured interview, based on nine questions was sent by e-mail to eleven addresses of relevant demographers in the second half of October 2013. The basic reason for sending questions by e-mail was the aspiration to obtain authentic replies which require time for contemplation. Ten completed questionnaires were returned within two weeks. On the one hand, an integral picture on the chosen themes for research was attempted to be obtained in the analysis of received opinions to certain groups of questions and on the other hand to portray the spectrum of different observations. The responses of our prominent demographers were analyzed and compared to clearly pronounced standpoints of eminent demographers published in world journals on similar themes and with findings of internet researches among members of the International Union for the Scientific Study of Population. Results: The results show that there is a high level of consent among demographers in Serbia regarding the well positioning of demography in relation to other social studies and its good perspectives. The interviewed experts see the future of demography in its integration with a wide circle of sciences, the application of demography and/or greater engagement of researchers in carrying out public policies. However, the estimations of the interviewed demographers as regards the development and state of demography in Serbia are divided. Although a large number of topics had been listed, migrations and population

  2. The effects of isolation on the demography and genetic diversity of long-lived species: Implications for conservation and management of the gopher tortoise (Gopherus polyphemus)

    Science.gov (United States)

    Ennen, J.R.; Birkhead, R.D.; Kreiser, B.R.; Gaillard, D.L.; Qualls, C.P.; Lovich, J.E.

    2011-01-01

    In the southeastern United States, habitat loss has fragmented the landscape and isolated many populations of this region's flora and fauna, which has presumably resulted in smaller population sizes and reduced levels of genetic diversity. For example, forestry practices and anthropogenic disturbances are both cited as factors fragmenting the once extensive range of Gopherus polyphemus. One localized, but extreme, source of fragmentation was the impoundment of the Chattahoochee River in 1963 to form Walter F. George Reservoir along the border of Georgia and Alabama. The formation of this reservoir isolated populations of G. polyphemus on two newly created islands providing a natural laboratory to explore the demographics and genetic effects of fragmentation on a long-lived species. These populations were first surveyed in 1984 and, 21 years later, we revisited them to collect demographic data and tissue samples for genetic analysis. We genotyped all individuals for 10 microsatellite loci, and we tested these data for bottlenecks and compared them to levels of genetic diversity for populations from other portions of the range. We found 45 and two individuals on the larger and smaller islands, respectively. On the large island, however, the population size was identical to the 1984 survey. Only the population structure based on estimated age differed between the 1984 and 2004 surveys, while population size structure based on carapace length, sex ratio, and sex-specific growth rates did not differ. The population of the large island showed genetic evidence of a past bottleneck. The genetic diversity indices from the population of the large island, however, were comparable to or greater than those found at mainland sites, in particular from western populations.

  3. Past climate change and recent anthropogenic activities affect genetic structure and population demography of the greater long-tailed hamster in northern China.

    Science.gov (United States)

    Ye, Junbin; Xiao, Zhenlong; Li, Chuanhai; Wang, Fusheng; Liao, Jicheng; Fu, Jinzhong; Zhang, Zhibin

    2015-09-01

    The genetic diversity and the spatial structure of a species are likely consequences of both past and recent evolutionary processes, but relevant studies are still rare in East Asia where the Pleistocene climate has unique influences. In this study, we examined the impact of past climate change and recent anthropogenic activities on the genetic structure and population size of the greater long-tailed hamster (Tscherskia triton), an agricultural rodent pest species in northern China. DNA sequence data of 2 mitochondrial genes and genotypic data of 11 microsatellite DNA loci from 41 populations (545 individuals) were gathered. Phylogenetic and population genetic analyses, as well as species distribution modeling and coalescent simulations, were conducted to infer its historical and demographic patterns and processes. Two deeply diverged mitochondrial clades were recovered. A small one was restricted to the Shandong Peninsula while the main clade was further divided into 3 geographic clusters by their microsatellite DNA genotypes: Northwest, North-center and Northeast. Divergence dating indicated a Middle-to-Late Pleistocene divergence between the 2 clades. Demographic analysis indicated that all 3 and pooled populations showed consistent long-period expansions during last glacial period; but not during the Holocene, probably due to the impact of climate warming and human disturbances. Conflicting patterns between mtDNA and microsatellite markers imply an anthropogenic impact on North-center populations due to intensified agricultural cultivation in this region. Our study demonstrated that the impact of past glaciation on organisms in East Asia significantly differs from that of Europe and North America, and human activity is an important factor in determining the genetic diversity of a species, as well as its spatial structure. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  4. [Romanian demography (1975-1989)].

    Science.gov (United States)

    Trebici, V

    1990-01-01

    The author describes developments in the study of demography in Romania over the period 1975-1989. The books and articles mentioned are classified by subject. The author notes that although few full-length monographs were published during the Ceausescu years, a steady stream of demographic articles appeared, most of which were published in the journal Viitorul Social, now retitled Sociologie Romaneasca.

  5. Influence of geology and human activity on the genetic structure and demography of the Oriental fire-bellied toad (Bombina orientalis).

    Science.gov (United States)

    Fong, Jonathan J; Li, Pi-Peng; Yang, Bao-Tian; Zhou, Zheng-Yan; Leaché, Adam D; Min, Mi-Sook; Waldman, Bruce

    2016-04-01

    The Oriental fire-bellied toad (Bombina orientalis) is a commonly used study organism, but knowledge of its evolutionary history is incomplete. We analyze sequence data from four genetic markers (mtDNA genes encoding cytochrome c oxidase subunit I, cytochrome b, and 12S-16S rRNA; nuDNA gene encoding recombination activating gene 2) from 188 individuals across its range in Northeast Asia to elucidate phylogeographic patterns and to identify the historic events that shaped its evolutionary history. Although morphologically similar across its range, B. orientalis exhibits phylogeographic structure, which we infer was shaped by geologic, climatic, and anthropogenic events. Phylogenetic and divergence-dating analyses recover four genetically distinct groups of B. orientalis: Lineage 1-Shandong Province and Beijing (China); Lineage 2-Bukhan Mountain (Korea); Lineage 3-Russia, Northeast China, and northern South Korea; and Lineage 4-South Korea. Lineage 2 was previously unknown. Additionally, we discover an area of secondary contact on the Korean Peninsula, and infer a single dispersal event as the origin of the insular Jeju population. Skyline plots estimate different population histories for the four lineages: Lineages 1 and 2 experienced population decreases, Lineage 3 remained stable, while Lineage 4 experienced a sharp increase during the Holocene. The timing of the population expansion of Lineage 4 coincides with the advent of rice cultivation, which may have facilitated the increase in population size by providing additional breeding habitat. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Genetic Structuration, Demography and Evolutionary History of Mycobacterium tuberculosis LAM9 Sublineage in the Americas as Two Distinct Subpopulations Revealed by Bayesian Analyses

    Science.gov (United States)

    Reynaud, Yann; Millet, Julie; Rastogi, Nalin

    2015-01-01

    Tuberculosis (TB) remains broadly present in the Americas despite intense global efforts for its control and elimination. Starting from a large dataset comprising spoligotyping (n = 21183 isolates) and 12-loci MIRU-VNTRs data (n = 4022 isolates) from a total of 31 countries of the Americas (data extracted from the SITVIT2 database), this study aimed to get an overview of lineages circulating in the Americas. A total of 17119 (80.8%) strains belonged to the Euro-American lineage 4, among which the most predominant genotypic family belonged to the Latin American and Mediterranean (LAM) lineage (n = 6386, 30.1% of strains). By combining classical phylogenetic analyses and Bayesian approaches, this study revealed for the first time a clear genetic structuration of LAM9 sublineage into two subpopulations named LAM9C1 and LAM9C2, with distinct genetic characteristics. LAM9C1 was predominant in Chile, Colombia and USA, while LAM9C2 was predominant in Brazil, Dominican Republic, Guadeloupe and French Guiana. Globally, LAM9C2 was characterized by higher allelic richness as compared to LAM9C1 isolates. Moreover, LAM9C2 sublineage appeared to expand close to twenty times more than LAM9C1 and showed older traces of expansion. Interestingly, a significant proportion of LAM9C2 isolates presented typical signature of ancestral LAM-RDRio MIRU-VNTR type (224226153321). Further studies based on Whole Genome Sequencing of LAM strains will provide the needed resolution to decipher the biogeographical structure and evolutionary history of this successful family. PMID:26517715

  7. Formal demography of families and households

    NARCIS (Netherlands)

    Willekens, F.J.; van Imhoff, E.; Wright, James D.

    2015-01-01

    ‘Family and household demography’ differs from traditional demography in that it explicitly recognizes and studies relationships between individuals. Formal demography focuses on the definition and measurement of families and households, and modeling of types, number, and composition of families and

  8. Parasites as prey

    NARCIS (Netherlands)

    Goedknegt, M.A.; Welsh, J.E.; Thieltges, D.W.

    2012-01-01

    Parasites are usually considered to use their hosts as a resource for energy. However, there is increasing awareness that parasites can also become a resource themselves and serve as prey for other organisms. Here we describe various types of predation in which parasites act as prey for other

  9. Prey detection and prey capture in copepod nauplii

    DEFF Research Database (Denmark)

    Bruno, Eleonora; Borg, Marc Andersen; Kiørboe, Thomas

    2012-01-01

    Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds...... (Temora longicornis). We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding...

  10. Introducing the new business demography statistics

    OpenAIRE

    Karen Grierson; Andrew Allen

    2008-01-01

    Introducing the new business demography statisticsA new National Statistics series waspublished on 28 November 2008 bythe Offi ce for National Statistics (ONS),providing data on business births,deaths and survival rates, called BusinessDemography: Enterprise Births andDeaths. The Department for Business,Enterprise & Regulatory Reform (BERR)also published its series Business start upsand closures: VAT registrations andde-registrations in 2007 on the sameday. The year 2008 is the final update t...

  11. The economics of protecting tiger populations: Linking household behavior to poaching and prey depletion

    Science.gov (United States)

    Damania, R.; Stringer, R.; Karanth, K.U.; Stith, B.

    2003-01-01

    The tiger (Panthera tigris) is classified as endangered and populations continue to decline. This paper presents a formal economic analysis of the two most imminent threats to the survival of wild tigers: poaching tigers and hunting their prey. A model is developed to examine interactions between tigers and farm households living in and around tiger habitats. The analysis extends the existing literature on tiger demography, incorporating predator-prey interactions and exploring the sensitivity of tiger populations to key economic parameters. The analysis aims to contribute to policy debates on how best to protect one of the world's most endangered wild cats.

  12. Prey detection and prey capture in copepod nauplii.

    Directory of Open Access Journals (Sweden)

    Eleonora Bruno

    Full Text Available Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds numbers due to the thick viscous boundary layer surrounding the attacking nauplius. We use high-speed video to describe the detection and capture of phytoplankton prey by the nauplii of two ambush feeding species (Acartia tonsa and Oithona davisae and by the nauplii of one feeding-current feeding species (Temora longicornis. We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding current that pulls in the prey from behind towards the mouth. The feeding-current feeding nauplius detects prey arriving in the feeding current but only when the prey is intercepted by the setae on the feeding appendages. This elicits an altered motion pattern of the feeding appendages that draws in the prey.

  13. The Allometry of Prey Preferences

    Science.gov (United States)

    Kalinkat, Gregor; Rall, Björn Christian; Vucic-Pestic, Olivera; Brose, Ulrich

    2011-01-01

    The distribution of weak and strong non-linear feeding interactions (i.e., functional responses) across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles) simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses) as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems. PMID:21998724

  14. The allometry of prey preferences.

    Directory of Open Access Journals (Sweden)

    Gregor Kalinkat

    Full Text Available The distribution of weak and strong non-linear feeding interactions (i.e., functional responses across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems.

  15. Changing demography of Sri Lanka.

    Science.gov (United States)

    De Silva, S

    1986-06-01

    The point to be made in this article about the changing demography of Sri Lanka is that demographic conditions (an older population and growth rate of 1.6) are favorable for economic growth. Planning for economic growth is demonstrated in discussing trends and their relationship to economic development rather than providing a macroeconomic analysis. The 1st demographic characteristic of importance is the age structure of the population, which identifies labor force potential, dependents, and those not economically active in order to calculate required social services. Consumer expenditure patterns are affected, as well as educational costs. The rapid mortality decline of the 1940's and the high fertility up to the 1960's created a broad based age structure that swelled student populations and labor force (unemployment). The 1980's is marked by 39% 15 years in 1981 versus 35% in 1971, and 6.4$ 60 years in 1981 versus 6.6% in 1971. Anticipated trends based on either 2.1, 2.5, or 2.9 children/mother indicate that the population structure would remain the same except for those 0-14 years. This amounts to 20-21.3 million by 2001 and 5.5-6.7 million 15 years. Economic planning is affected by the following age groups: preschoolers, school age children, working population, and old age population. A gradual decline in preschoolers would eventually lead to a 9% population versus a 13% in 2001. 23% of the current population of 5-14 year olds will decrease after 1996 with slow or medium growth to 19-21%. The next 2 decades will experience a swelling of the working age population from 9.56 million to 12.7 million, which was 15 years ago the total population figure. The rate change is from 58.2% to 60-63%. By 2001 the 60 year old population will be 9% (1.8 million) or equal to those 5 years. Attention, thus, needs to be paid to the equitability of distribution of services and improvement in quality rather than expansion. New jobs need to be created to prevent high unemployment

  16. Genetic hemoglobin disorders rather than iron deficiency are a major predictor of hemoglobin concentration in women of reproductive age in rural prey Veng, Cambodia.

    Science.gov (United States)

    Karakochuk, Crystal D; Whitfield, Kyly C; Barr, Susan I; Lamers, Yvonne; Devlin, Angela M; Vercauteren, Suzanne M; Kroeun, Hou; Talukder, Aminuzzaman; McLean, Judy; Green, Timothy J

    2015-01-01

    Anemia is common in Cambodian women. Potential causes include micronutrient deficiencies, genetic hemoglobin disorders, inflammation, and disease. We aimed to investigate factors associated with anemia (low hemoglobin concentration) in rural Cambodian women (18-45 y) and to investigate the relations between hemoglobin disorders and other iron biomarkers. Blood samples were obtained from 450 women. A complete blood count was conducted, and serum and plasma were analyzed for ferritin, soluble transferrin receptor (sTfR), folate, vitamin B-12, retinol binding protein (RBP), C-reactive protein (CRP), and α1 acid glycoprotein (AGP). Hemoglobin electrophoresis and multiplex polymerase chain reaction were used to determine the prevalence and type of genetic hemoglobin disorders. Overall, 54% of women had a genetic hemoglobin disorder, which included 25 different genotypes (most commonly, hemoglobin E variants and α(3.7)-thalassemia). Of the 420 nonpregnant women, 29.5% had anemia (hemoglobin 8.3 mg/L), hemoglobin disorders, respectively. There was no biochemical evidence of vitamin A deficiency (RBP 5 mg/L) and 26% (AGP >1 g/L) of nonpregnant women, respectively. By using an adjusted linear regression model, the strongest predictors of hemoglobin concentration were hemoglobin E homozygous disorder and pregnancy status. Other predictors were 2 other heterozygous traits (hemoglobin E and Constant Spring), parity, RBP, log ferritin, and vitamin B-12. Multiple biomarkers for anemia and iron deficiency were significantly influenced by the presence of hemoglobin disorders, hence reducing their diagnostic sensitivity. Further investigation of the unexpectedly low prevalence of IDA in Cambodian women is warranted. © 2015 American Society for Nutrition.

  17. Gender inequality: The challenge of contemporary demography

    OpenAIRE

    Šobot Ankica

    2010-01-01

    Gender perspective is a heuristic device in researching social phenomena, and gender inequality is a social fact which requires an adequate answer. Also, social differences between women and men are examined as relevant factors of demographic phenomena. The contemporary demography is opening up space not only for the gender aspect, but also for gender inequality as a relevant research topic. This paper discusses the possibilities of demographic approach to studying social inequality between w...

  18. Fertility transition: forecast for demography.

    Science.gov (United States)

    Caputo, M; Nicotra, M; Gloria-Bottini, E

    2008-08-01

    By the end of the 20th century most industrialized nations had undergone the so-called fertility transition, characterized by a reduction in fertility to below replacement level and a delay in age at initiation of child-bearing. An emerging concern is the severe economic and social consequences of this demographic decline. We present an overview of fertility changes in Italy in the second half of the 20th century and a mathematical model that may provide projections for the future of the demographic situation. Starting in 1950 the increment of the number of children born in Italy is initially positive; however, beginning in 1965 the trend suddenly becomes negative, and this negative trend further increased in 1975. A slight improvement is observed in 1980, followed by a stable situation beginning in 1987. Relevant socioeconomic and cultural events in Italy coincide with these variations in the fertility trend. Malnutrition, which had been endemic for centuries in some areas of central and southern Italy, disappeared rather abruptly in early 1960. The improvement in the economic situation was also associated with a decrease in illiteracy and with many sociocultural changes, with the emergence of new demands that decreased propensity for childbearing. The additional deceleration observed in 1975 corresponds to the diffusion of contraceptive procedures. The progression of sociocultural changes has led to a progressive liberation of women from the biological burden of childbearing. Two phenomena seem relevant in this context: women's emerging interest in entering the workforce and the possibility to disconnect sex from childbearing. The social function of feminism has overwhelmed the primary function of survival and diffusion of the species, giving rise to relevant and worrying demographic effects. However, the modern woman has an unconscious memory of her primary biological role, depending on both her genetic structure and cultural heritage, that should bring about a

  19. Coalescent Processes with Skewed Offspring Distributions and Nonequilibrium Demography.

    Science.gov (United States)

    Matuszewski, Sebastian; Hildebrandt, Marcel E; Achaz, Guillaume; Jensen, Jeffrey D

    2018-01-01

    Nonequilibrium demography impacts coalescent genealogies leaving detectable, well-studied signatures of variation. However, similar genomic footprints are also expected under models of large reproductive skew, posing a serious problem when trying to make inference. Furthermore, current approaches consider only one of the two processes at a time, neglecting any genomic signal that could arise from their simultaneous effects, preventing the possibility of jointly inferring parameters relating to both offspring distribution and population history. Here, we develop an extended Moran model with exponential population growth, and demonstrate that the underlying ancestral process converges to a time-inhomogeneous psi-coalescent. However, by applying a nonlinear change of time scale-analogous to the Kingman coalescent-we find that the ancestral process can be rescaled to its time-homogeneous analog, allowing the process to be simulated quickly and efficiently. Furthermore, we derive analytical expressions for the expected site-frequency spectrum under the time-inhomogeneous psi-coalescent, and develop an approximate-likelihood framework for the joint estimation of the coalescent and growth parameters. By means of extensive simulation, we demonstrate that both can be estimated accurately from whole-genome data. In addition, not accounting for demography can lead to serious biases in the inferred coalescent model, with broad implications for genomic studies ranging from ecology to conservation biology. Finally, we use our method to analyze sequence data from Japanese sardine populations, and find evidence of high variation in individual reproductive success, but few signs of a recent demographic expansion. Copyright © 2018 by the Genetics Society of America.

  20. Large-scale climatic anomalies affect marine predator foraging behaviour and demography

    Science.gov (United States)

    Bost, Charles A.; Cotté, Cedric; Terray, Pascal; Barbraud, Christophe; Bon, Cécile; Delord, Karine; Gimenez, Olivier; Handrich, Yves; Naito, Yasuhiko; Guinet, Christophe; Weimerskirch, Henri

    2015-10-01

    Determining the links between the behavioural and population responses of wild species to environmental variations is critical for understanding the impact of climate variability on ecosystems. Using long-term data sets, we show how large-scale climatic anomalies in the Southern Hemisphere affect the foraging behaviour and population dynamics of a key marine predator, the king penguin. When large-scale subtropical dipole events occur simultaneously in both subtropical Southern Indian and Atlantic Oceans, they generate tropical anomalies that shift the foraging zone southward. Consequently the distances that penguins foraged from the colony and their feeding depths increased and the population size decreased. This represents an example of a robust and fast impact of large-scale climatic anomalies affecting a marine predator through changes in its at-sea behaviour and demography, despite lack of information on prey availability. Our results highlight a possible behavioural mechanism through which climate variability may affect population processes.

  1. Economics of population versus economic demography

    Directory of Open Access Journals (Sweden)

    A. A. Tkachenko

    2017-01-01

    Full Text Available The article specifies the correlation between economic demography and the economy of population as the most important scientific areas of modern research. It is concluded that the Russian scientific community lags in the development of these sciences from the world scientific thought. Special attention is paid to the works and ideas of S. Kuznets and Amartya Sen as outstanding researchers of the interrelationships between the population and the economy. It is emphasized that their contribution was not only theoretical but also of practical importance. The importance of G. Myrdal’s works for modern studies of the consequences of population aging is considered. The article examines foreign training courses on “Population Economics”, presented at the Universities of Wisconsin and McMaster, their analysis led to the conclusion that the preparation of textbooks on courses is less productive than the use of scientific articles in journals, containing more recent ideas and achievements of science. The author considers the system, proposed in the course Michel Grignon and Byron G. Spencer «The Economics of Population» more preferable. The article substantiates the opinion that the economic theory of well-being should be the core of the population economy. It is concluded that the differences between economic demography and the economy of population are not just differences between the micro- and macro levels, as some authors write, but the transition to large scales and entropy.The author identifies three most important areas of demo-economic research, which include research in the field of human capital, international economic migration, especially remittance, analysis of the stratification of the population and society by the income in the global and national economies. One can single out the general area of interests of the population economy and economic demography in which these sciences are almost impossible to divide and in which only

  2. What you need is what you eat? Prey selection by the bat Myotis daubentonii.

    Science.gov (United States)

    Vesterinen, Eero J; Ruokolainen, Lasse; Wahlberg, Niklas; Peña, Carlos; Roslin, Tomas; Laine, Veronika N; Vasko, Ville; Sääksjärvi, Ilari E; Norrdahl, Kai; Lilley, Thomas M

    2016-04-01

    Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod abundances. According to optimal foraging theory, prehibernating bats should adopt a less selective feeding behavior--yet empirical studies have revealed many apparently generalized species to be composed of specialist individuals. Targeting the diet of the bat Myotis daubentonii, we used a combination of molecular techniques to test for seasonal changes in prey selectivity and individual-level variation in prey preferences. DNA metabarcoding was used to characterize both the prey contents of bat droppings and the insect community available as prey. To test for dietary differences among M. daubentonii individuals, we used ten microsatellite loci to assign droppings to individual bats. The comparison between consumed and available prey revealed a preference for certain prey items regardless of availability. Nonbiting midges (Chironomidae) remained the most highly consumed prey at all times, despite a significant increase in the availability of black flies (Simuliidae) towards the end of the season. The bats sampled showed no evidence of individual specialization in dietary preferences. Overall, our approach offers little support for optimal foraging theory. Thus, it shows how novel combinations of genetic markers can be used to test general theory, targeting patterns at both the level of prey communities and individual predators. © 2016 John Wiley & Sons Ltd.

  3. Prey capture by harbour porpoises

    DEFF Research Database (Denmark)

    Verfuss, Ursula; Miller, Lee; Pilz, Peter

    their ultrasonic clicks as biosonar for orientation and detection of prey (mostly smaller pelagic and bottom dwelling fish), and for communication.  For studying wild animals, hydrophone arrays [Villadsgaard et al. J.Exp.Biol. 210 (2007)] and acoustic (time/depth) tags [Akamatsu et al. Deep Sea Research II 54...... (2007)] have been used.  For studying captive animals, arrays and video techniques [Verfuß et al. J.Exp.Biol. 208 (2005)] as well as miniature acoustic-behavioral tags [Deruiter et al. JASA 123 (2008)] have been used.  While searching for prey, harbor porpoises use clicks at long intervals (>50 ms......) that progressively decrease when closing on a landmark.  The source levels of captive animals reduce by about half for each halving of the distance to the target.  After detecting the prey, the click interval first stabilizes at about 50 ms and then becomes progressively shorter while approaching the prey...

  4. Dynamics analysis of a predator-prey system with harvesting prey and disease in prey species.

    Science.gov (United States)

    Meng, Xin-You; Qin, Ni-Ni; Huo, Hai-Feng

    2018-12-01

    In this paper, a predator-prey system with harvesting prey and disease in prey species is given. In the absence of time delay, the existence and stability of all equilibria are investigated. In the presence of time delay, some sufficient conditions of the local stability of the positive equilibrium and the existence of Hopf bifurcation are obtained by analysing the corresponding characteristic equation, and the properties of Hopf bifurcation are given by using the normal form theory and centre manifold theorem. Furthermore, an optimal harvesting policy is investigated by applying the Pontryagin's Maximum Principle. Numerical simulations are performed to support our analytic results.

  5. Sub-indicator: Prey fish

    Science.gov (United States)

    Weidel, Brian C.; Dunlop, Erin

    2017-01-01

    Prey fish communities across the Great Lakes continue to change, although the direction and magnitude of those changes are not consistent across the lakes. The metrics used to categorize prey fish status in this and previous periods are based on elements that are common among each of the lake’s Fish Community Objectives and include diversity and the relative role of native species in the prey fish communities. The diversity index categorized three of lakes as ‘fair’, while Superior and Erie were ‘good’ (Table 1). The short term trend, from the previous period (2008-2010) to the current period (2011-2014) found diversity in Erie and Superior to be unchanging, but the other three lakes to be ‘deteriorating’, resulting in an overall trend categorization of ‘undetermined’ (Table 1). The long term diversity trend suggested Lakes Superior and Erie have the most diverse prey communities although the index for those prey fish have been quite variable over time (Figure 1). In Lake Huron, where non-native alewife have substantially declined, the diversity index has also declined. The continued dominance of alewife in Lake Ontario (96% of the prey fish biomass) resulted in the lowest diversity index value (Figure 1). The proportion of native species within the community was judged as ‘good’ in Lakes Superior and Huron, ‘fair’ in Michigan and Erie and ‘poor’ in Ontario (Table 2). The short term trend was improving in in all lakes except Michigan (‘deteriorating’) and Ontario (‘unchanging’), resulting in an overall short term trend of ‘undetermined’ (Table 2). Over the current period, Lake Superior consistently had the highest proportion native prey fish (87%) while Lake Ontario had the lowest (1%) (Figure 2). Lake Michigan’s percent native has declined as round goby increase and comprises a greater proportion of the community. Native prey fish make up 51% of Lake Erie, although basin-specific values differed (Figure 2). Most notably

  6. Prey preference follows phylogeny: evolutionary dietary patterns within the marine gastropod group Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia).

    Science.gov (United States)

    Goodheart, Jessica A; Bazinet, Adam L; Valdés, Ángel; Collins, Allen G; Cummings, Michael P

    2017-10-26

    The impact of predator-prey interactions on the evolution of many marine invertebrates is poorly understood. Since barriers to genetic exchange are less obvious in the marine realm than in terrestrial or freshwater systems, non-allopatric divergence may play a fundamental role in the generation of biodiversity. In this context, shifts between major prey types could constitute important factors explaining the biodiversity of marine taxa, particularly in groups with highly specialized diets. However, the scarcity of marine specialized consumers for which reliable phylogenies exist hampers attempts to test the role of trophic specialization in evolution. In this study, RNA-Seq data is used to produce a phylogeny of Cladobranchia, a group of marine invertebrates that feed on a diverse array of prey taxa but mostly specialize on cnidarians. The broad range of prey type preferences allegedly present in two major groups within Cladobranchia suggest that prey type shifts are relatively common over evolutionary timescales. In the present study, we generated a well-supported phylogeny of the major lineages within Cladobranchia using RNA-Seq data, and used ancestral state reconstruction analyses to better understand the evolution of prey preference. These analyses answered several fundamental questions regarding the evolutionary relationships within Cladobranchia, including support for a clade of species from Arminidae as sister to Tritoniidae (which both preferentially prey on Octocorallia). Ancestral state reconstruction analyses supported a cladobranchian ancestor with a preference for Hydrozoa and show that the few transitions identified only occur from lineages that prey on Hydrozoa to those that feed on other types of prey. There is strong phylogenetic correlation with prey preference within Cladobranchia, suggesting that prey type specialization within this group has inertia. Shifts between different types of prey have occurred rarely throughout the evolution of

  7. Disentangling the effects of demography and selection in human history.

    Science.gov (United States)

    Stajich, Jason E; Hahn, Matthew W

    2005-01-01

    Demographic events affect all genes in a genome, whereas natural selection has only local effects. Using publicly available data from 151 loci sequenced in both European-American and African-American populations, we attempt to distinguish the effects of demography and selection. To analyze large sets of population genetic data such as this one, we introduce "Perlymorphism," a Unix-based suite of analysis tools. Our analyses show that the demographic histories of human populations can account for a large proportion of effects on the level and frequency of variation across the genome. The African-American population shows both a higher level of nucleotide diversity and more negative values of Tajima's D statistic than does a European-American population. Using coalescent simulations, we show that the significantly negative values of the D statistic in African-Americans and the positive values in European-Americans are well explained by relatively simple models of population admixture and bottleneck, respectively. Working within these nonequilibrium frameworks, we are still able to show deviations from neutral expectations at a number of loci, including ABO and TRPV6. In addition, we show that the frequency spectrum of mutations--corrected for levels of polymorphism--is correlated with recombination rate only in European-Americans. These results are consistent with repeated selective sweeps in non-African populations, in agreement with recent reports using microsatellite data.

  8. Ecosystem Demography Model: Scaling Vegetation Dynamics Across South America

    Data.gov (United States)

    National Aeronautics and Space Administration — This model product contains the source code for the Ecosystem Demography Model (ED version 1.0) as well as model input and output data for a portion of South America...

  9. Ecosystem Demography Model: Scaling Vegetation Dynamics Across South America

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This model product contains the source code for the Ecosystem Demography Model (ED version 1.0) as well as model input and output data for a portion of...

  10. Genetic diversity and historical demography of kuruma shrimp ...

    African Journals Online (AJOL)

    ... of kuruma shrimp ( Penaeus japonicus ) species complex off China based on ... of 454-bp at 5' end of mitochondrial DNA control region were conducted. ... analyses suggested a late Pleistocene population expansion for both variety I ...

  11. Genetic diversity and historical demography of Chinese shrimp ...

    African Journals Online (AJOL)

    Both mismatch distribution analyses and neutrality tests suggested a late Pleistocene or Holocene population expansion (12,100 – 28,500 years ago) for the species, which was consistent with the geological period of formation of the Yellow Sea and Bohai Sea. These results indicated that F. chinensis in the Yellow Sea and ...

  12. Prey capture by harbor porpoises

    DEFF Research Database (Denmark)

    Miller, Lee; Verfuss, Ursula

    2009-01-01

    their ultrasonic clicks as biosonar for orientation and detection of prey (mostly smaller pelagic and bottom dwelling fish), and for communication. For studying wild animals, hydrophone arrays and acoustic (time/depth) tags have been used. For studying captive animals, arrays and video techniques as well...

  13. DIM SUM: demography and individual migration simulated using a Markov chain.

    Science.gov (United States)

    Brown, Jeremy M; Savidge, Kevin; McTavish, Emily Jane B

    2011-03-01

    An increasing number of studies seek to infer demographic history, often jointly with genetic relationships. Despite numerous analytical methods for such data, few simulations have investigated the methods' power and robustness, especially when underlying assumptions have been violated. DIM SUM (Demography and Individual Migration Simulated Using a Markov chain) is a stand-alone Java program for the simulation of population demography and individual migration while recording ancestor-descendant relationships. It does not employ coalescent assumptions or discrete population boundaries. It is extremely flexible, allowing the user to specify border positions, reactions of organisms to borders, local and global carrying capacities, individual dispersal kernels, rates of reproduction and strategies for sampling individuals. Spatial variables may be specified using image files (e.g., as exported from gis software) and may vary through time. In combination with software for genetic marker simulation, DIM SUM will be useful for testing phylogeographic (e.g., nested clade phylogeographic analysis, coalescent-based tests and continuous-landscape frameworks) and landscape-genetic methods, specifically regarding violations of coalescent assumptions. It can also be used to explore the qualitative features of proposed demographic scenarios (e.g. regarding biological invasions) and as a pedagogical tool. DIM SUM (with user's manual) can be downloaded from http://code.google.com/p/bio-dimsum. © 2010 Blackwell Publishing Ltd.

  14. Two-prey one-predator model

    International Nuclear Information System (INIS)

    Elettreby, M.F.

    2009-01-01

    In this paper we propose a new multi-team prey-predator model, in which the prey teams help each other. We study its local stability. In the absence of predator, there is no help between the prey teams. So, we study the global stability and persistence of the model without help.

  15. Prey detection in a cruising copepod

    DEFF Research Database (Denmark)

    Kjellerup, Sanne; Kiørboe, Thomas

    2012-01-01

    . Yet, direct interception has been proposed to explain how rapidly cruising, blind copepods feed on non-motile phytoplankton prey. Here, we demonstrate a novel mechanism for prey detection in a cruising copepod, and describe how motile and non-motile prey are discovered by hydromechanical and tactile...

  16. Linking extreme interannual changes in prey availability to foraging behaviour and breeding investment in a marine predator, the macaroni penguin.

    Science.gov (United States)

    Horswill, Cat; Trathan, Philip N; Ratcliffe, Norman

    2017-01-01

    Understanding the mechanisms that link prey availability to predator behaviour and population change is central to projecting how a species may respond to future environmental pressures. We documented the behavioural responses and breeding investment of macaroni penguins Eudyptes chrysolophus across five breeding seasons where local prey density changed by five-fold; from very low to highly abundant. When prey availability was low, foraging trips were significantly longer and extended overnight. Birds also foraged farther from the colony, potentially in order to reach more distant foraging grounds and allow for increased search times. These extended foraging trips were also linked to a marked decrease in fledgling weights, most likely associated with reduced rates of provisioning. Furthermore, by comparing our results with previous work on this population, it appears that lowered first-year survival rates associated, at least partially, with fledging masses were also evident for this cohort. This study integrates a unique set of prey density, predator behaviour and predator breeding investment data to highlight a possible behavioural mechanism linking perturbations in prey availability to population demography.

  17. Linking extreme interannual changes in prey availability to foraging behaviour and breeding investment in a marine predator, the macaroni penguin.

    Directory of Open Access Journals (Sweden)

    Cat Horswill

    Full Text Available Understanding the mechanisms that link prey availability to predator behaviour and population change is central to projecting how a species may respond to future environmental pressures. We documented the behavioural responses and breeding investment of macaroni penguins Eudyptes chrysolophus across five breeding seasons where local prey density changed by five-fold; from very low to highly abundant. When prey availability was low, foraging trips were significantly longer and extended overnight. Birds also foraged farther from the colony, potentially in order to reach more distant foraging grounds and allow for increased search times. These extended foraging trips were also linked to a marked decrease in fledgling weights, most likely associated with reduced rates of provisioning. Furthermore, by comparing our results with previous work on this population, it appears that lowered first-year survival rates associated, at least partially, with fledging masses were also evident for this cohort. This study integrates a unique set of prey density, predator behaviour and predator breeding investment data to highlight a possible behavioural mechanism linking perturbations in prey availability to population demography.

  18. When attempts at robbing prey turn fatal

    Science.gov (United States)

    Dejean, Alain; Corbara, Bruno; Azémar, Frédéric; Carpenter, James M.

    2012-07-01

    Because group-hunting arboreal ants spread-eagle insect prey for a long time before retrieving them, these prey can be coveted by predatory flying insects. Yet, attempting to rob these prey is risky if the ant species is also an effective predator. Here, we show that trying to rob prey from Azteca andreae workers is a fatal error as 268 out of 276 potential cleptobionts (97.1 %) were captured in turn. The ant workers hunt in a group and use the "Velcro®" principle to cling firmly to the leaves of their host tree, permitting them to capture very large prey. Exceptions were one social wasp, plus some Trigona spp. workers and flies that landed directly on the prey and were able to take off immediately when attacked. We conclude that in this situation, previously captured prey attract potential cleptobionts that are captured in turn in most of the cases.

  19. Demography of a forest elephant population

    Science.gov (United States)

    Turkalo, Andrea K.; Wrege, Peter H.

    2018-01-01

    African forest elephants face severe threats from illegal killing for ivory and bushmeat and habitat conversion. Due to their cryptic nature and inaccessible range, little information on the biology of this species has been collected despite its iconic status. Compiling individual based monitoring data collected over 20 years from the Dzanga Bai population in Central African Republic, we summarize sex and age specific survivorship and female age specific fecundity for a cohort of 1625 individually identified elephants. Annual mortality (average = 3.5%) and natality (average = 5.3%) were lower and markedly less variable relative to rates reported for savanna elephant populations. New individuals consistently entered the study system, leading to a 2.5% average annual increase in the registered population. Calf sex ratios among known birth did not differ from parity. A weak seasonal signal in births was detected suggesting increased conceptions during the wet season. Inter-calf intervals and age of primiparity were longer relative to savanna elephant populations. Within the population, females between the ages of 25–39 demonstrated the shortest inter-calf intervals and highest fecundity, and previous calf sex had no influence on the interval. Calf survivorship was high (97%) the first two years after birth and did not differ by sex. Male and female survival began to differ by the age of 13 years, and males demonstrated significantly lower survival relative to females by the age of 20. It is suspected these differences are driven by human selection for ivory. Forest elephants were found to have one of the longest generation times recorded for any species at 31 years. These data provide fundamental understanding of forest elephant demography, providing baseline data for projecting population status and trends. PMID:29447207

  20. Fear affects parental care, which predicts juvenile survival and exacerbates the total cost of fear on demography.

    Science.gov (United States)

    Dudeck, Blair P; Clinchy, Michael; Allen, Marek C; Zanette, Liana Y

    2018-01-01

    Fear itself (perceived predation risk) can affect wildlife demography, but the cumulative impact of fear on population dynamics is not well understood. Parental care is arguably what most distinguishes birds and mammals from other taxa, yet only one experiment on wildlife has tested fear effects on parental food provisioning and the repercussions this has for the survival of dependent offspring, and only during early-stage care. We tested the effect of fear on late-stage parental care of mobile dependent offspring, by locating radio-tagged Song Sparrow fledglings and broadcasting predator or non-predator playbacks in their vicinity, measuring their parent's behavior and their own, and tracking the offspring's survival to independence. Fear significantly reduced late-stage parental care, and parental fearfulness (as indexed by their reduction in provisioning when hearing predators) significantly predicted their offspring's condition and survival. Combining results from this experiment with that on early-stage care, we project that fear itself is powerful enough to reduce late-stage survival by 24%, and cumulatively reduce the number of young reaching independence by more than half, 53%. Experiments in invertebrate and aquatic systems demonstrate that fear is commonly as important as direct killing in affecting prey demography, and we suggest focusing more on fear effects and on offspring survival will reveal the same for wildlife. © 2017 by the Ecological Society of America.

  1. Political demography: Powerful trends under-attended by demographic science.

    Science.gov (United States)

    Teitelbaum, Michael S

    2015-01-01

    The interconnections between politics and the dramatic demographic changes under way around the world have been neglected by the two research disciplines that could contribute most to their understanding: demography and political science. Instead, this area of 'political demography' has largely been ceded to political activists, pundits, and journalists, leading often to exaggerated or garbled interpretation. The terrain includes some of the most politically sensitive and contested issues: alleged demographically determined shifts in the international balance of power; low fertility, population decline, and demographic ageing; international migration; change in national identity; and compositional shifts in politically sensitive social categories and human rights. Meanwhile many governments and non-governmental actors have actively pursued varieties of 'strategic demography', deploying fertility, mortality, or migration as instruments of domestic or international policy. Political scientists and demographers could and should use their knowledge and analytic techniques to improve understanding and to moderate excessive claims and fears on these topics.

  2. Demography of Dall's sheep in northwestern Alaska

    Science.gov (United States)

    Kleckner, Christopher; Udevitz, Mark S.; Adams, Layne G.; Shults, Brad S.

    2003-01-01

    largely from studies in central or southern Alaska and the southern Yukon. However, sheep in northwestern Alaska are at the northwestern extreme of their range and live in a less hospitable environment characterized by short growing seasons and long, severe winters. We expect patterns of productivity and survival for sheep in Noatak National Preserve to differ from the more southerly populations. To adequately manage sheep harvests in northwestern Alaska, we need a better understanding of sheep demography. Along with unbiased population estimates, understanding the dynamics of sheep populations in the region will allow population models to be developed that can provide focus for a useful dialog on management goals and strategies and facilitate a cooperative strategy for managing sheep harvests in northwestern Alaska.

  3. Myxobacteria Are Able to Prey Broadly upon Clinically-Relevant Pathogens, Exhibiting a Prey Range Which Cannot Be Explained by Phylogeny

    Directory of Open Access Journals (Sweden)

    Paul G. Livingstone

    2017-08-01

    Full Text Available Myxobacteria are natural predators of microorganisms and the subjects of concerted efforts to identify novel antimicrobial compounds. Myxobacterial predatory activity seems to require more than just the possession of specific antimicrobial metabolites. Thus a holistic approach to studying predation promises novel insights into antimicrobial action. Here, we report the isolation of 113 myxobacteria from samples of soil taken from a range of habitats in mid Wales. Predatory activity of each isolate was quantified against a panel of clinically important prey organisms, including Klebsiella pneumoniae, Proteus mirabilis, Candida albicans, Enterococcus faecalis, and three species of Staphylococcus. Myxobacterial isolates exhibited a wide range of predation activity profiles against the panel of prey. Efficient predation of all prey by isolates within the collection was observed, with K. pneumoniae and C. albicans proving particularly susceptible to myxobacterial predation. Notably efficient predators tended to be proficient at predating multiple prey organisms, suggesting they possess gene(s encoding a broad range killing activity. However, predatory activity was not congruent with phylogeny, suggesting prey range is subject to relatively rapid specialization, potentially involving lateral gene transfer. The broad but patchy prey ranges observed for natural myxobacterial isolates also implies multiple (potentially overlapping genetic determinants are responsible for dictating predatory activity.

  4. The modeling of predator-prey interactions

    OpenAIRE

    Muhammad Shakil; H. A. Wahab; Muhammad Naeem, et al.

    2015-01-01

    In this paper, we aim to study the interactions between the territorial animals like foxes and the rabbits. The territories for the foxes are considered to be the simple cells. The interactions between predator and its prey are represented by the chemical reactions which obey the mass action law. In this sense, we apply the mass action law for predator prey models and the quasi chemical approach is applied for the interactions between the predator and its prey to develop the modeled equations...

  5. "Prey Play": Learning about Predators and Prey through an Interactive, Role-Play Game

    Science.gov (United States)

    Deaton, Cynthia C. M.; Dodd, Kristen; Drennon, Katherine; Nagle, Jack

    2012-01-01

    "Prey Play" is an interactive role-play activity that provides fifth-grade students with opportunities to examine predator-prey interactions. This four-part, role-play activity allows students to take on the role of a predator and prey as they reflect on the behaviors animals exhibit as they collect food and interact with one another, as well as…

  6. Soviet theories of economic demography: a survey.

    Science.gov (United States)

    Gregory, P

    1983-06-01

    At this time Soviet demographic scientists maintain the position that population problems may in fact exist temporarily under socialism but that the planning principle will allow society to resolve population problems, through the use of the administrative, moral, and economic levers (subsidies, government policies, propaganda, education) emphasized by Urlanis (1974) and others. For planners to deal effectively with population management, the determinants of fertility and labor force participation must be established. The foundations of Soviet theories of human capital and fertility were laid by several writers. For the sake of simplicity, these are referred to as the Urlanis-Strumilin model, named after 2 pioneer researchers in Soviet demography and manpower economics. The formulations are based upon the writings of Strumlin (1964) and Urlanis (1974), supplemented by writings of numerous other Soviet researchers. Although their models avoid neoclassical terms such as marginal utility and income and price elasticities, they clearly employ these concepts. The Urlanis-Strumilin model, reduced to its basic elements, is a direct household utility maximizing model. The husband and wife, the household decision makers, must select optimal levels of child "quantity," child "quality," leisure, their own human capital (further education and training), and other goods. The Soviet theory recognizes that an increase in household income will increase relatively the demands for income elastic goods. The model postulates that the demand for child quality is inversely related to the price of children. The price of children is the opportunity cost of children, the major element of which is the income foregone by the mother in the course of childbearing and childrearing. The child quantity demand schedule has elastic and inelastic portions. The marginal utility of the 1st child is great. The marginal utilities of higher order children decline substantially. Families with at least 1

  7. Rattans of Vietnam: ecology, demography and harvesting

    NARCIS (Netherlands)

    Bui, My Binh

    2009-01-01

    Rattans are spiny climbing palms belonging to the Arecaceae family. Rattans may be single-stemmed or multi-stemmed in which stems (ramet) are clustered in a clump (genet). Rattan is an important non-timber forest product (NTFP) in almost all Southeast Asian countries. As demand for rattan products

  8. Prey size spectra and prey availability of larval and small juvenile cod

    DEFF Research Database (Denmark)

    Munk, Peter

    1997-01-01

    The aim of the present study is to describe the prey preference characteristics of cod larvae and assess preference variability in relation to species and size composition of copepod prey. A further aim is to examine the hypothesis that dietary prey size spectra remain the same during the larval ...... were indicated, dependent on location. The findings illustrate the usefulness of coupling dietary prey size spectra and biomass spectra of available prey sizes during studies of ichthyoplankton feeding ecology. (C) 1997 The Fisheries Society of the British Isles....

  9. Relating marten scat contents to prey consumed

    Science.gov (United States)

    William J. Zielinski

    1986-01-01

    A European ferret, Mustela putorius furo, was fed typical marten food items to discover the relationship between prey weight and number of scats produced per unit weight of prey. A correction factor was derived that was used in the analysis of pine marten, Martes americana, scats to produce a method capable of comparing foods on a...

  10. Optimal intermittent search strategies: smelling the prey

    International Nuclear Information System (INIS)

    Revelli, J A; Wio, H S; Rojo, F; Budde, C E

    2010-01-01

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of α (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  11. Optimal intermittent search strategies: smelling the prey

    Energy Technology Data Exchange (ETDEWEB)

    Revelli, J A; Wio, H S [Instituto de Fisica de Cantabria, Universidad de Cantabria and CSIC, E-39005 Santander (Spain); Rojo, F; Budde, C E [Fa.M.A.F., Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina)

    2010-05-14

    We study the kinetics of the search of a single fixed target by a searcher/walker that performs an intermittent random walk, characterized by different states of motion. In addition, we assume that the walker has the ability to detect the scent left by the prey/target in its surroundings. Our results, in agreement with intuition, indicate that the prey's survival probability could be strongly reduced (increased) if the predator is attracted (or repelled) by the trace left by the prey. We have also found that, for a positive trace (the predator is guided towards the prey), increasing the inhomogeneity's size reduces the prey's survival probability, while the optimal value of {alpha} (the parameter that regulates intermittency) ceases to exist. The agreement between theory and numerical simulations is excellent.

  12. Interdisciplinary approach to the demography of Jamaica.

    Science.gov (United States)

    Deason, Michael L; Salas, Antonio; Newman, Simon P; Macaulay, Vincent A; St A Morrison, Errol Y; Pitsiladis, Yannis P

    2012-02-23

    The trans-Atlantic slave trade dramatically changed the demographic makeup of the New World, with varying regions of the African coast exploited differently over roughly a 400 year period. When compared to the discrete mitochondrial haplotype distribution of historically appropriate source populations, the unique distribution within a specific source population can prove insightful in estimating the contribution of each population. Here, we analyzed the first hypervariable region of mitochondrial DNA in a sample from the Caribbean island of Jamaica and compared it to aggregated populations in Africa divided according to historiographically defined segments of the continent's coastline. The results from these admixture procedures were then compared to the wealth of historic knowledge surrounding the disembarkation of Africans on the island. In line with previous findings, the matriline of Jamaica is almost entirely of West African descent. Results from the admixture analyses suggest modern Jamaicans share a closer affinity with groups from the Gold Coast and Bight of Benin despite high mortality, low fecundity, and waning regional importation. The slaves from the Bight of Biafra and West-central Africa were imported in great numbers; however, the results suggest a deficit in expected maternal contribution from those regions. When considering the demographic pressures imposed by chattel slavery on Jamaica during the slave era, the results seem incongruous. Ethnolinguistic and ethnographic evidence, however, may explain the apparent non-random levels of genetic perseverance. The application of genetics may prove useful in answering difficult demographic questions left by historically voiceless groups.

  13. Prey preferences of the jaguar Panthera onca reflect the post-Pleistocene demise of large prey.

    Directory of Open Access Journals (Sweden)

    Matt W Hayward

    2016-01-01

    Full Text Available Documenting the impacts of the Pleistocene megafaunal extinctions on predator-prey interactions is a challenge because of the incomplete fossil record and depauperate extant community structure. We used a comparative ecological approach to investigate whether the existing prey preference patterns of jaguars Panthera onca were potentially affected by the Pleistocene extinctions in the Americas compared with large felids in Africa and Asia. We reviewed the literature and found 25 studies reporting 3214 jaguar kills recorded throughout the species’ distribution. We found that jaguars significantly preferred capybara Hydrochaeris hydrochaeris and giant anteater Myrmecophaga tridactyla, and avoided agoutis, carnivorans, primates, black-eared opossum Didelphis marsupialis and tapirs. Generalised linear models showed that jaguars select prey primarily based on socio-ecological and behavioural traits (abundance and herd size, rather than morphological characteristics (body size. Nonetheless, their accessible prey weight range was 6-60 kg, preferred prey weight range was 45-85 kg, and mean mass of significantly preferred prey was 32 ± 13 kg leading to a predator to prey body mass ratio of 1:0.53, which is much less than that of other solitary felids. Compared with other large, solitary felids, jaguars have an unusual predator to prey body mass ratio, show limited effect of prey morphology as a driver of prey selection, lack evidence of optimal foraging beyond their preferred prey, and an absence of preferentially hunting on Cetartiodactyla herbivores. These features, coupled with the reduction in jaguar body mass since the Pleistocene, suggest that the loss of larger potential prey items within the preferred and accessible weight ranges at the end-Pleistocene still affects jaguar predatory behaviour. It may be that jaguars survived this mass extinction event by preferentially preying on relatively small species.

  14. Statistical methods with applications to demography and life insurance

    CERN Document Server

    Khmaladze, Estáte V

    2013-01-01

    Suitable for statisticians, mathematicians, actuaries, and students interested in the problems of insurance and analysis of lifetimes, Statistical Methods with Applications to Demography and Life Insurance presents contemporary statistical techniques for analyzing life distributions and life insurance problems. It not only contains traditional material but also incorporates new problems and techniques not discussed in existing actuarial literature. The book mainly focuses on the analysis of an individual life and describes statistical methods based on empirical and related processes. Coverage ranges from analyzing the tails of distributions of lifetimes to modeling population dynamics with migrations. To help readers understand the technical points, the text covers topics such as the Stieltjes, Wiener, and Itô integrals. It also introduces other themes of interest in demography, including mixtures of distributions, analysis of longevity and extreme value theory, and the age structure of a population. In addi...

  15. The Dynamics of a Nonautonomous Predator-Prey Model with Infertility Control in the Prey

    Directory of Open Access Journals (Sweden)

    Xiaomei Feng

    2014-01-01

    Full Text Available A nonautonomous predator-prey model with infertility control in the prey is formulated and investigated. Threshold conditions for the permanence and extinction of fertility prey and infertility prey are established. Some new threshold values of integral form are obtained. For the periodic cases, these threshold conditions act as sharp threshold values for the permanence and extinction of fertility prey and infertility prey. There are also mounting concerns that the quantity of biological sterile drug is obtained in the process of the prevention and control of pest in the grasslands and farmland. Finally, two examples are given to illustrate the main results of this paper. The numerical simulations shown that, when the pest population is permanet, different dynamic behaviors may be found in this model, such as the global attractivity and the chaotic attractor.

  16. Gluttonous predators: how to estimate prey size when there are too many prey

    Directory of Open Access Journals (Sweden)

    MS. Araújo

    Full Text Available Prey size is an important factor in food consumption. In studies of feeding ecology, prey items are usually measured individually using calipers or ocular micrometers. Among amphibians and reptiles, there are species that feed on large numbers of small prey items (e.g. ants, termites. This high intake makes it difficult to estimate prey size consumed by these animals. We addressed this problem by developing and evaluating a procedure for subsampling the stomach contents of such predators in order to estimate prey size. Specifically, we developed a protocol based on a bootstrap procedure to obtain a subsample with a precision error of at the most 5%, with a confidence level of at least 95%. This guideline should reduce the sampling effort and facilitate future studies on the feeding habits of amphibians and reptiles, and also provide a means of obtaining precise estimates of prey size.

  17. Prey-mediated avoidance of an intraguild predator by its intraguild prey

    Science.gov (United States)

    Wilson, R.R.; Blankenship, T.L.; Hooten, M.B.; Shivik, J.A.

    2010-01-01

    Intraguild (IG) predation is an important factor influencing community structure, yet factors allowing coexistence of IG predator and IG prey are not well understood. The existence of spatial refuges for IG prey has recently been noted for their importance in allowing coexistence. However, reduction in basal prey availability might lead IG prey to leave spatial refuges for greater access to prey, leading to increased IG predation and fewer opportunities for coexistence. We determined how the availability of prey affected space-use patterns of bobcats (Lynx rufus, IG prey) in relation to coyote space-use patterns (Canis latrans, IG predators). We located animals from fall 2007 to spring 2009 and estimated bobcat home ranges and core areas seasonally. For each bobcat relocation, we determined intensity of coyote use, distance to water, small mammal biomass, and mean small mammal biomass of the home range during the season the location was collected. We built generalized linear mixed models and used Akaike Information Criteria to determine which factors best predicted bobcat space use. Coyote intensity was a primary determinant of bobcat core area location. In bobcat home ranges with abundant prey, core areas occurred where coyote use was low, but shifted to areas intensively used by coyotes when prey declined. High spatial variability in basal prey abundance allowed some bobcats to avoid coyotes while at the same time others were forced into more risky areas. Our results suggest that multiple behavioral strategies associated with spatial variation in basal prey abundance likely allow IG prey and IG predators to coexist. ?? 2010 Springer-Verlag.

  18. Are lemmings prey or predators?

    Science.gov (United States)

    Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.

    2000-06-01

    Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.

  19. Molecular insights into the historic demography of bowhead whales: understanding the evolutionary basis of contemporary management practices

    Science.gov (United States)

    Phillips, C D; Hoffman, J I; George, J C; Suydam, R S; Huebinger, R M; Patton, J C; Bickham, J W

    2013-01-01

    Patterns of genetic variation observed within species reflect evolutionary histories that include signatures of past demography. Understanding the demographic component of species' history is fundamental to informed management because changes in effective population size affect response to environmental change and evolvability, the strength of genetic drift, and maintenance of genetic variability. Species experiencing anthropogenic population reductions provide valuable case studies for understanding the genetic response to demographic change because historic changes in the census size are often well documented. A classic example is the bowhead whale, Balaena mysticetus, which experienced dramatic population depletion due to commercial whaling in the late 19th and early 20th centuries. Consequently, we analyzed a large multi-marker dataset of bowhead whales using a variety of analytical methods, including extended Bayesian skyline analysis and approximate Bayesian computation, to characterize genetic signatures of both ancient and contemporary demographic histories. No genetic signature of recent population depletion was recovered through any analysis incorporating realistic mutation assumptions, probably due to the combined influences of long generation time, short bottleneck duration, and the magnitude of population depletion. In contrast, a robust signal of population expansion was detected around 70,000 years ago, followed by a population decline around 15,000 years ago. The timing of these events coincides to a historic glacial period and the onset of warming at the end of the last glacial maximum, respectively. By implication, climate driven long-term variation in Arctic Ocean productivity, rather than recent anthropogenic disturbance, appears to have been the primary driver of historic bowhead whale demography. PMID:23403722

  20. Unraveling the effects of selection and demography on immune gene variation in free-ranging plains zebra (Equus quagga) populations.

    Science.gov (United States)

    Kamath, Pauline L; Getz, Wayne M

    2012-01-01

    Demography, migration and natural selection are predominant processes affecting the distribution of genetic variation among natural populations. Many studies use neutral genetic markers to make inferences about population history. However, the investigation of functional coding loci, which directly reflect fitness, is critical to our understanding of species' ecology and evolution. Immune genes, such as those of the Major Histocompatibility Complex (MHC), play an important role in pathogen recognition and provide a potent model system for studying selection. We contrasted diversity patterns of neutral data with MHC loci, ELA-DRA and -DQA, in two southern African plains zebra (Equus quagga) populations: Etosha National Park, Namibia, and Kruger National Park, South Africa. Results from neutrality tests, along with observations of elevated diversity and low differentiation across populations, supported previous genus-level evidence for balancing selection at these loci. Despite being low, MHC divergence across populations was significant and may be attributed to drift effects typical of geographically separated populations experiencing little to no gene flow, or alternatively to shifting allele frequency distributions driven by spatially variable and fluctuating pathogen communities. At the DRA, zebra exhibited geographic differentiation concordant with microsatellites and reduced levels of diversity in Etosha due to highly skewed allele frequencies that could not be explained by demography, suggestive of spatially heterogeneous selection and local adaptation. This study highlights the complexity in which selection affects immune gene diversity and warrants the need for further research on the ecological mechanisms shaping patterns of adaptive variation among natural populations.

  1. Unraveling the effects of selection and demography on immune gene variation in free-ranging plains zebra (Equus quagga populations.

    Directory of Open Access Journals (Sweden)

    Pauline L Kamath

    Full Text Available Demography, migration and natural selection are predominant processes affecting the distribution of genetic variation among natural populations. Many studies use neutral genetic markers to make inferences about population history. However, the investigation of functional coding loci, which directly reflect fitness, is critical to our understanding of species' ecology and evolution. Immune genes, such as those of the Major Histocompatibility Complex (MHC, play an important role in pathogen recognition and provide a potent model system for studying selection. We contrasted diversity patterns of neutral data with MHC loci, ELA-DRA and -DQA, in two southern African plains zebra (Equus quagga populations: Etosha National Park, Namibia, and Kruger National Park, South Africa. Results from neutrality tests, along with observations of elevated diversity and low differentiation across populations, supported previous genus-level evidence for balancing selection at these loci. Despite being low, MHC divergence across populations was significant and may be attributed to drift effects typical of geographically separated populations experiencing little to no gene flow, or alternatively to shifting allele frequency distributions driven by spatially variable and fluctuating pathogen communities. At the DRA, zebra exhibited geographic differentiation concordant with microsatellites and reduced levels of diversity in Etosha due to highly skewed allele frequencies that could not be explained by demography, suggestive of spatially heterogeneous selection and local adaptation. This study highlights the complexity in which selection affects immune gene diversity and warrants the need for further research on the ecological mechanisms shaping patterns of adaptive variation among natural populations.

  2. When prey provide more than food: mammalian predators appropriating the refugia of their prey

    Science.gov (United States)

    Bill Zielinski

    2015-01-01

    Some mammalian predators acquire both food and shelter from their prey, by eating them and using the refugia the prey construct. I searched the literature for examples of predators that exhibit this behavior and summarize their taxonomic affiliations, relative sizes, and distributions. I hypothesized that size ratios of species involved in this dynamic would be near 1....

  3. Genetics

    International Nuclear Information System (INIS)

    Hubitschek, H.E.

    1975-01-01

    Progress is reported on the following research projects: genetic effects of high LET radiations; genetic regulation, alteration, and repair; chromosome replication and the division cycle of Escherichia coli; effects of radioisotope decay in the DNA of microorganisms; initiation and termination of DNA replication in Bacillus subtilis; mutagenesis in mouse myeloma cells; lethal and mutagenic effects of near-uv radiation; effect of 8-methoxypsoralen on photodynamic lethality and mutagenicity in Escherichia coli; DNA repair of the lethal effects of far-uv; and near uv irradiation of bacterial cells

  4. Predation risk affects reproductive physiology and demography of elk.

    Science.gov (United States)

    Creel, Scott; Christianson, David; Liley, Stewart; Winnie, John A

    2007-02-16

    Elk (Cervus elaphus) in the Greater Yellowstone Ecosystem alter patterns of aggregation, habitat selection, vigilance, and foraging in the presence of wolves (Canis lupus). Antipredator behaviors like these can reduce predation risk but are also likely to carry costs. Data from five elk populations studied for 16 site years showed that progesterone concentrations (from 1489 fecal samples) declined with the ratio of elk to wolves. In turn, progesterone concentrations were a good predictor of calf recruitment in the subsequent year. Together, these data suggest that wolves indirectly affect the reproductive physiology and the demography of elk through the costs of antipredator behavior.

  5. Selective Predation of a Stalking Predator on Ungulate Prey.

    Directory of Open Access Journals (Sweden)

    Marco Heurich

    Full Text Available Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1 data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2 data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates.

  6. Prey responses to predator chemical cues: disentangling the importance of the number and biomass of prey consumed.

    Directory of Open Access Journals (Sweden)

    Michael W McCoy

    Full Text Available To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey consumed. In this study we determine whether phenotypic plasticity to predator chemical cues depends upon prey biomass consumed, prey number consumed, or both. We examine the growth response of red-eyed treefrog tadpoles (Agalychnis callidryas to cues from a larval dragonfly (Anax amazili. Biomass consumed was manipulated by either increasing the number of prey while holding individual prey size constant, or by holding the number of prey constant and varying individual prey size. We address two questions. (i Do prey reduce growth rate in response to chemical cues in a dose dependent manner? (ii Does the magnitude of the response depend on whether prey consumption increases via number or size of prey? We find that the phenotypic response of prey is an asymptotic function of prey biomass consumed. However, the asymptotic response is higher when more prey are consumed. Our findings have important implications for evaluating past studies and how future experiments should be designed. A stronger response to predation cues generated by more individual prey deaths is consistent with models that predict prey sensitivity to per capita risk, providing a more direct link between empirical and theoretical studies which are often focused on changes in population sizes not individual biomass.

  7. Genetics

    DEFF Research Database (Denmark)

    Christensen, Kaare; McGue, Matt

    2016-01-01

    The sequenced genomes of individuals aged ≥80 years, who were highly educated, self-referred volunteers and with no self-reported chronic diseases were compared to young controls. In these data, healthy ageing is a distinct phenotype from exceptional longevity and genetic factors that protect...

  8. Microbiological survey of birds of prey pellets.

    Science.gov (United States)

    Dipineto, Ludovico; Bossa, Luigi Maria De Luca; Pace, Antonino; Russo, Tamara Pasqualina; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Caputo, Vincenzo; Fioretti, Alessandro

    2015-08-01

    A microbiological survey of 73 pellets collected from different birds of prey species housed at the Wildlife Rescue and Rehabilitation Center of Napoli (southern Italy) was performed. Pellets were analyzed by culture and biochemical methods as well as by serotyping and polymerase chain reaction. We isolated a wide range of bacteria some of them also pathogens for humans (i.e. Salmonella enterica serotype Typhimurium, Campylobacter coli, Escherichia coli O serogroups). This study highlights the potential role of birds of prey as asymptomatic carriers of pathogenic bacteria which could be disseminated in the environment not only through the birds of prey feces but also through their pellets. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Prey capture by freely swimming flagellates

    Science.gov (United States)

    Andersen, Anders; Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas

    2017-11-01

    Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. Here, we explore the dependence of swimming kinematics and prey clearance rate on flagellar arrangement and determine optimal flagellar arrangements and essential trade-offs. To describe near-cell flows around freely swimming flagellates we consider a model in which the cell is represented by a no-slip sphere and each flagellum by a point force. For uniflagellates pulled by a single flagellum the model suggests that a long flagellum favors fast swimming, whereas high clearance rate is favored by a very short flagellum. For biflagellates with both a longitudinal and a transversal flagellum we explore the helical swimming kinematics and the prey capture sites. We compare our predictions with observations of swimming kinematics, prey capture, and flows around common marine flagellates. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

  10. Non-webbuilding spiders: prey specialists or generalists?

    Science.gov (United States)

    Nentwig, Wolfgang

    1986-07-01

    Feeding experiments were performed with seven species of non-webbuilding spiders and a variety of prey taxa. Some species were generally polyphagous whereas other spiders restricted their prey to a few groups. At one end of the spectrum of prey specialization the thomisid Misumena vatia is limited to a few taxa of possible prey (Table 1). The literature of prey records of non-webbuilding spiders is reviewed (Table 2) with special emphasis on oligophagous or monophagous spiders. Monophagous spiders are generally rare and have specialized on only a few prey taxa: social insects (ants, bees, termites) and spiders.

  11. Interactive effects of prey refuge and additional food for predator in a diffusive predator-prey system

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S.K.

    2017-01-01

    a predator-prey system with prey refuge and additional food for predator apart from the focal prey in the presence of diffusion. Our main aim is to study the interactive effects of prey refuge and additional food on the system dynamics and especially on the controllability of prey (pest). Different types......Additional food for predators has been considered as one of the best established techniques in integrated pest management and biological conservation programs. In natural systems, there are several other factors, e.g., prey refuge, affect the success of pest control. In this paper, we analyze...... of Turing patterns such as stripes, spots, holes, and mixtures of them are obtained. It is found that the supply of additional food to the predator is unable to control the prey (pest) population when prey refuge is high. Moreover, when both prey refuge and additional food are low, spatial distribution...

  12. Gendered Authorship and Demographic Research : An Analysis of 50 Years of Demography

    NARCIS (Netherlands)

    Krapf, Sandra; Kreyenfeld, Michaela; Wolf, Katharina

    2016-01-01

    Demography, the official journal of the Population Association of America, has been given the highest rating among demographic journals by the Social Sciences Citation Index (SSCI). Our aim here is to investigate the development of research subfields and female authorship in Demography over the last

  13. Demography of Honors: The Census of U.S. Honors Programs and Colleges

    Science.gov (United States)

    Scott, Richard I.; Smith, Patricia J.; Cognard-Black, Andrew J.

    2017-01-01

    Beginning in 2013 and spanning four research articles, we have implemented an empirical analysis protocol for honors education that is rooted in demography (Scott; Scott and Smith; Smith and Scott "Growth"; Smith and Scott, "Demography"). The goal of this protocol is to describe the structure and distribution of the honors…

  14. Can species-specific prey responses to chemical cues explain prey susceptibility to predation?

    Science.gov (United States)

    Šmejkal, Marek; Ricard, Daniel; Sajdlová, Zuzana; Čech, Martin; Vejřík, Lukáš; Blabolil, Petr; Vejříková, Ivana; Prchalová, Marie; Vašek, Mojmír; Souza, Allan T; Brönmark, Christer; Peterka, Jiří

    2018-05-01

    The perception of danger represents an essential ability of prey for gaining an informational advantage over their natural enemies. Especially in complex environments or at night, animals strongly rely on chemoreception to avoid predators. The ability to recognize danger by chemical cues and subsequent adaptive responses to predation threats should generally increase prey survival. Recent findings suggest that European catfish ( Silurus glanis ) introduction induce changes in fish community and we tested whether the direction of change can be attributed to differences in chemical cue perception. We tested behavioral response to chemical cues using three species of freshwater fish common in European water: rudd ( Scardinius erythrophthalmus ), roach ( Rutilus rutilus ), and perch ( Perca fluviatilis ). Further, we conducted a prey selectivity experiment to evaluate the prey preferences of the European catfish. Roach exhibited the strongest reaction to chemical cues, rudd decreased use of refuge and perch did not alter any behavior in the experiment. These findings suggest that chemical cue perception might be behind community data change and we encourage collecting more community data of tested prey species before and after European catfish introduction to test the hypothesis. We conclude that used prey species can be used as a model species to verify whether chemical cue perception enhances prey survival.

  15. Demography and ecology of nuclear power plant location

    International Nuclear Information System (INIS)

    Stefanescu, P.; Ghitescu, P.

    1997-01-01

    To select and licence a NPP site, as well as, once built, to run it, both demography and ecology of the geographical zone are crucial factors to take into account. On the other side the location and running of a NPP is a major factor in the economic and social development of NPP site surroundings. Meanwhile the population distribution around the NPP site has a determining role on intervention and rehabilitation plans. Risk and danger studies should be done for initial situation as well as during NPP running. The character of radioactive risks and the importance of possible consequences of a hypothetical nuclear accident which could affect a big Nuclear Power Plant request a special attention to population distribution around the plant site and surroundings. Therefore safety studies to locate and licence a site should refer to demography and ecology. Available data examination will permit to locate NPP in less-populated and ecologically not-concerning zones. On-site investigation should identify the population groups to watch for in order to estimate the results of a normal evaluation. The inquires will give reference primary data before NPP construction starts. Also they evaluate the possibility of short term population retain on location in case of an accident. (authors)

  16. Predator-prey encounters in turbulent waters

    DEFF Research Database (Denmark)

    Mann, J.; Ott, Søren; Pécseli, H.L.

    2002-01-01

    With reference to studies of predator-prey encounters in turbulent waters, we demonstrate the feasibility of an experimental method for investigations of particle fluxes to an absorbing surface in turbulent flows. A laboratory experiment is carried out, where an approximately homogeneous and isot......With reference to studies of predator-prey encounters in turbulent waters, we demonstrate the feasibility of an experimental method for investigations of particle fluxes to an absorbing surface in turbulent flows. A laboratory experiment is carried out, where an approximately homogeneous...

  17. Wild North Island Robins (Petroica longipes respond to Prey Animacy

    Directory of Open Access Journals (Sweden)

    Alexis Garland

    2014-08-01

    Full Text Available North Island robins of New Zealand are a food hoarding species, which is unique in that they almost exclusively cache highly perishable hunted insects for later retrieval. In order to do so, they either kill and dismember or paralyze their prey for caching, depending on the prey size and kind. The present study comprises two experiments, using a Violation of Expectancy (VoE paradigm to examine variation in search behavior response to different prey conditions. The first experiment presents three different types of prey (mealworms, earthworms and locusts in expected (present and unexpected (absent conditions. The second experiment presents prey in varying states of animacy (alive and whole, dead and whole, dead and halved, and an inanimate stick and reveals prey in expected (same state or unexpected (differing state conditions. While robins did not respond with differential search times to different types of unexpectedly missing prey in Experiment 1, in Experiment 2 robins searched longer in conditions where prey was found in a differing state of animacy than initially shown. Robins also searched longer for prey when immediately consuming retrieved prey than when caching retrieved prey. Results indicate that North Island robins may be sensitive to prey animacy upon storage and retrieval of insect prey; such information could play a role in storage, pilfering and retrieval strategies of such a perishable food source.

  18. Prey switching behaviour in the planktonic copepod Acartia tonsa

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Saiz, E.; Viitasalo, M.

    1996-01-01

    The copepod Acartia tonsa has 2 different prey encounter strategies. It can generate a feeding current to encounter and capture immobile prey (suspension feeding) or it can sink slowly and perceive motile prey by means of mechanoreceptors on the antennae (ambush feeding). We hypothesized that A....... tonsa adopts the feeding mode that generates the highest energy intake rate; i.e. that prey selection changes according to the relative concentrations of alternative prey (prey switching) and that the copepods spend disproportionately more time in the feeding mode that provides the greatest reward...... be captured by suspension feeding copepods. Finally, we demonstrate that turbulence favours the selection of ciliates as prey. We suggest that prey switching by copepods may provide survival windows for microzooplankters during blooms of net phytoplankton because predation pressure from the copepods...

  19. Models of prey capture in larval fish

    NARCIS (Netherlands)

    Drost, M.R.

    1986-01-01

    The food uptake of larval carp and pike is described from high speed movies with synchronous lateral and ventral views.

    During prey intake by larval fishes the velocities of the created suction flow are high relative to their own size: 0.3 m/s for carp larvae of 6

  20. Lake Ontario benthic prey fish assessment, 2015

    Science.gov (United States)

    Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

    2016-01-01

    Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single

  1. Killer whale prey - Determining prey selection by southern resident killer whales (SRKW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Prey selectivity by southern resident killer whales is being determined by analyses of fish scales and tissue from predation events and feces. Information on killer...

  2. Prey-Predator Model with a Nonlocal Bistable Dynamics of Prey

    Directory of Open Access Journals (Sweden)

    Malay Banerjee

    2018-03-01

    Full Text Available Spatiotemporal pattern formation in integro-differential equation models of interacting populations is an active area of research, which has emerged through the introduction of nonlocal intra- and inter-specific interactions. Stationary patterns are reported for nonlocal interactions in prey and predator populations for models with prey-dependent functional response, specialist predator and linear intrinsic death rate for predator species. The primary goal of our present work is to consider nonlocal consumption of resources in a spatiotemporal prey-predator model with bistable reaction kinetics for prey growth in the absence of predators. We derive the conditions of the Turing and of the spatial Hopf bifurcation around the coexisting homogeneous steady-state and verify the analytical results through extensive numerical simulations. Bifurcations of spatial patterns are also explored numerically.

  3. SRKW summer prey - Prey species and stock specific consumption estimates for SRKW in their summer range

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Southern Resident Killer Whales (SRKW) are listed as a Distinct Population Segment under the Endangered Species Act. Data concerning their prey species and stock...

  4. Prey aggregation is an effective olfactory predator avoidance strategy

    Directory of Open Access Journals (Sweden)

    Asa Johannesen

    2014-05-01

    Full Text Available Predator–prey interactions have a major effect on species abundance and diversity, and aggregation is a well-known anti-predator behaviour. For immobile prey, the effectiveness of aggregation depends on two conditions: (a the inability of the predator to consume all prey in a group and (b detection of a single large group not being proportionally easier than that of several small groups. How prey aggregation influences predation rates when visual cues are restricted, such as in turbid water, has not been thoroughly investigated. We carried out foraging (predation experiments using a fish predator and (dead chironomid larvae as prey in both laboratory and field settings. In the laboratory, a reduction in visual cue availability (in turbid water led to a delay in the location of aggregated prey compared to when visual cues were available. Aggregated prey suffered high mortality once discovered, leading to better survival of dispersed prey in the longer term. We attribute this to the inability of the dead prey to take evasive action. In the field (where prey were placed in feeding stations that allowed transmission of olfactory but not visual cues, aggregated (large groups and semi-dispersed prey survived for longer than dispersed prey—including long term survival. Together, our results indicate that similar to systems where predators hunt using vision, aggregation is an effective anti-predator behaviour for prey avoiding olfactory predators.

  5. Competition and Dispersal in Predator-Prey Waves

    NARCIS (Netherlands)

    Savill, N.J.; Hogeweg, P.

    1998-01-01

    Dispersing predators and prey can exhibit complex spatio-temporal wave-like patterns if the interactions between them cause oscillatory dynamics. We study the effect of these predator- prey density waves on the competition between prey populations and between predator popu- lations with different

  6. Predatory mites avoid ovipositing near counter-attacking prey

    NARCIS (Netherlands)

    Faraji, F.; Janssen, A.; Sabelis, M.W.

    2001-01-01

    Attacking prey is not without risk; predators may endure counterattackby the prey. Here, we study the oviposition behaviour of a predatory mite(Iphiseius degenerans) in relation to its prey, thewesternflower thrips (Frankliniella occidentalis). This thrips iscapable of killing the eggs of the

  7. Prey perception in feeding-current feeding copepods

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Goncalves, Rodrigo J.; Florian Couespel, Damien

    2016-01-01

    We reply to the comments of Paffenhöfer and Jiang () who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey concentrati......We reply to the comments of Paffenhöfer and Jiang () who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey...... cells have short intense leakage burst, only a very small fraction of prey cells would be available to the copepod at any instance in time and, thus would be inefficient at low prey concentration. Finally, we report a few new observations of prey capture in two species of copepods, Temora longicornis...... and Centropages hamatus, offered a 45-μm sized dinoflagellate at very low concentration. The observed short prey detection distances, up to a few prey cell radii, are consistent with mechanoreception and we argue briefly that near-field mechanoreception is the most likely and common prey perception mechanism...

  8. The functional response to prey density in an acarine system

    NARCIS (Netherlands)

    Fransz, H.G.

    1974-01-01

    Predacious mites are considered to be important natural enemies of phytophagous mites. Their efficiency in the natural control of prey populations depends on the relationships of the number of prey killed per predator per time unit and the oviposition rate on the one hand and prey density on the

  9. Turing-Hopf bifurcations in a predator-prey model with herd behavior, quadratic mortality and prey-taxis

    Science.gov (United States)

    Liu, Xia; Zhang, Tonghua; Meng, Xinzhu; Zhang, Tongqian

    2018-04-01

    In this paper, we propose a predator-prey model with herd behavior and prey-taxis. Then, we analyze the stability and bifurcation of the positive equilibrium of the model subject to the homogeneous Neumann boundary condition. By using an abstract bifurcation theory and taking prey-tactic sensitivity coefficient as the bifurcation parameter, we obtain a branch of stable nonconstant solutions bifurcating from the positive equilibrium. Our results show that prey-taxis can yield the occurrence of spatial patterns.

  10. Historical demography of common carp estimated from individuals collected from various parts of the world using the pairwise sequentially markovian coalescent approach.

    Science.gov (United States)

    Yuan, Zihao; Huang, Wei; Liu, Shikai; Xu, Peng; Dunham, Rex; Liu, Zhanjiang

    2018-04-01

    The inference of historical demography of a species is helpful for understanding species' differentiation and its population dynamics. However, such inference has been previously difficult due to the lack of proper analytical methods and availability of genetic data. A recently developed method called Pairwise Sequentially Markovian Coalescent (PSMC) offers the capability for estimation of the trajectories of historical populations over considerable time periods using genomic sequences. In this study, we applied this approach to infer the historical demography of the common carp using samples collected from Europe, Asia and the Americas. Comparison between Asian and European common carp populations showed that the last glacial period starting 100 ka BP likely caused a significant decline in population size of the wild common carp in Europe, while it did not have much of an impact on its counterparts in Asia. This was probably caused by differences in glacial activities in East Asia and Europe, and suggesting a separation of the European and Asian clades before the last glacial maximum. The North American clade which is an invasive population shared a similar demographic history as those from Europe, consistent with the idea that the North American common carp probably had European ancestral origins. Our analysis represents the first reconstruction of the historical population demography of the common carp, which is important to elucidate the separation of European and Asian common carp clades during the Quaternary glaciation, as well as the dispersal of common carp across the world.

  11. Mitochondrial DNA regionalism and historical demography in the extant populations of Chirocephalus kerkyrensis (Branchiopoda: Anostraca).

    Science.gov (United States)

    Ketmaier, Valerio; Marrone, Federico; Alfonso, Giuseppe; Paulus, Kirsten; Wiemann, Annika; Tiedemann, Ralph; Mura, Graziella

    2012-01-01

    Mediterranean temporary water bodies are important reservoirs of biodiversity and host a unique assemblage of diapausing aquatic invertebrates. These environments are currently vanishing because of increasing human pressure. Chirocephalus kerkyrensis is a fairy shrimp typical of temporary water bodies in Mediterranean plain forests and has undergone a substantial decline in number of populations in recent years due to habitat loss. We assessed patterns of genetic connectivity and phylogeographic history in the seven extant populations of the species from Albania, Corfu Is. (Greece), Southern and Central Italy. We analyzed sequence variation at two mitochondrial DNA genes (Cytochrome Oxidase I and 16s rRNA) in all the known populations of C. kerkyrensis. We used multiple phylogenetic, phylogeographic and coalescence-based approaches to assess connectivity and historical demography across the whole distribution range of the species. C. kerkyrensis is genetically subdivided into three main mitochondrial lineages; two of them are geographically localized (Corfu Is. and Central Italy) and one encompasses a wide geographic area (Albania and Southern Italy). Most of the detected genetic variation (≈81%) is apportioned among the aforementioned lineages. Multiple analyses of mismatch distributions consistently supported both past demographic and spatial expansions with the former predating the latter; demographic expansions were consistently placed during interglacial warm phases of the Pleistocene while spatial expansions were restricted to cold periods. Coalescence methods revealed a scenario of past isolation with low levels of gene flow in line with what is already known for other co-distributed fairy shrimps and suggest drift as the prevailing force in promoting local divergence. We recommend that these evolutionary trajectories should be taken in proper consideration in any effort aimed at protecting Mediterranean temporary water bodies.

  12. A work bibliography on native food consumption, demography and lifestyle

    International Nuclear Information System (INIS)

    Murray, C.E.; Lee, W.J.

    1992-12-01

    The purpose of this report is to provide a bibliography for the Native American tribe participants in the Hanford Environmental Dose Reconstruction (HEDR) Project to use. The HEDR Project's primary objective is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy's Hanford Site near Richland, Washington. Eight Native American tribes are responsible for estimating daily and seasonal consumption of traditional foods, demography, and other lifestyle factors that could have affected the radiation dose received by tribal members. This report provides a bibliography of recorded accounts that tribal researchers may use to verify their estimates. The bibliographic citations include references to information on the specific tribes, Columbia River plateau ethnobotany, infant feeding practices and milk consumption, nutritional studies and radiation, tribal economic and demographic characteristics (1940--1970), research methods, primary sources from the National Archives, regional archives, libraries, and museums

  13. A work bibliography on native food consumption, demography and lifestyle

    Energy Technology Data Exchange (ETDEWEB)

    Murray, C.E.; Lee, W.J.

    1992-12-01

    The purpose of this report is to provide a bibliography for the Native American tribe participants in the Hanford Environmental Dose Reconstruction (HEDR) Project to use. The HEDR Project's primary objective is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy's Hanford Site near Richland, Washington. Eight Native American tribes are responsible for estimating daily and seasonal consumption of traditional foods, demography, and other lifestyle factors that could have affected the radiation dose received by tribal members. This report provides a bibliography of recorded accounts that tribal researchers may use to verify their estimates. The bibliographic citations include references to information on the specific tribes, Columbia River plateau ethnobotany, infant feeding practices and milk consumption, nutritional studies and radiation, tribal economic and demographic characteristics (1940--1970), research methods, primary sources from the National Archives, regional archives, libraries, and museums.

  14. Effects of drought and prolonged winter on Townsend's ground squirrel demography in shrubsteppe habitats

    Science.gov (United States)

    Van Horne, Beatrice; Olson, Gail S.; Schooley, Robert L.; Corn, Janelle G.; Burnham, Kenneth P.

    1997-01-01

    During a mark–recapture study of Townsend's ground squirrels (Spermophilus townsendii) on 20 sites in the Snake River Birds of Prey National Conservation Area, Idaho, in 1991 through 1994, 4407 animals were marked in 17639 capture events. This study of differences in population dynamics of Townsend's ground squirrels among habitats spanned a drought near the extreme of the 130-yr record, followed by prolonged winter conditions.Townsend's ground squirrels have a short active season (≈4 mo) in which to reproduce and store fat for overwintering. Their food consists largely of succulent grasses and forbs in this dry shrubsteppe and grassland habitat. The drought in the latter half of the 1992 active season produced early drying of Sandberg's bluegrass (Poa secunda) and was associated with low adult and juvenile body masses prior to immergence into estivation/hibernation. The following prolonged winter was associated with late emergence of females in 1993. Early-season body masses of adults were low in 1993 relative to 1992, whereas percentage of body fat in males was relatively high. These weather patterns in spring 1992 and winter 1993 also resulted in reduced adult persistence through the ≈7-mo inactive period, especially for adult females, and near-zero persistence of >1200 juveniles. Consequently, densities of Townsend's ground squirrels across the 20 livetrap sites declined.The demographic effects of drought and prolonged winter lasted at least through the subsequent breeding season. Adult females that survived these weather extremes produced fewer emergent young per female than did adult females prior to the event. Prior to the drought/prolonged winter, yearling female body masses were higher than, or indistinguishable from, those of adults. Females produced in 1993 had lower body masses as yearlings than did adult females.Demographic response to the drought and prolonged winter varied with habitat; ground squirrels in sagebrush habitat showed less decline

  15. Are all prey created equal? A review and synthesis of differential predation on prey in substandard condition

    Science.gov (United States)

    Mesa, Matthew G.; Poe, Thomas P.; Gadomski, Dena M.; Petersen, James H.

    1994-01-01

    Our understanding of predator-prey interactions in fishes has been influenced largely by research assuming that the condition of the participants is normal. However, fish populations today often reside in anthropogenically altered environments and are subjected to many kinds of stressors, which may reduce their ecological performance by adversely affecting their morphology, physiology, or behaviour. One consequence is that either the predator or prey, or both, may be in a substandard condition at the time of an interaction. We reviewed the literature on predator-prey interactions in fishes where substandard prey were used as experimental groups. Although most of this research indicates that such prey are significantly more vulnerable to predation, prey condition has rarely been considered in ecological theory regarding predator-prey interactions. The causal mechanisms for increased vulnerability of substandard prey to predation include a failure to detect predators, lapses in decision-making, poor fast-start performance, inability to shoal effectively, and increased prey conspicuousness. Despite some problems associated with empirical predator-prey studies using substandard prey, their results can have theoretical and applied uses, such as in ecological modelling or justification of corrective measures to be implemented in the wild. There is a need for more corroborative field experimentation, a better understanding of the causal mechanisms behind differential predation, and increased incorporation of prey condition into the research of predator-prey modellers and theoreticians. If the concept of prey condition is considered in predator-prey interactions, our understanding of how such interactions influence the structure and dynamics of fish communities is likely to change, which should prove beneficial to aquatic ecosystems.

  16. Neuromuscular control of prey capture in frogs.

    OpenAIRE

    Nishikawa, K C

    1999-01-01

    While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular cont...

  17. Molecular prey identification in Central European piscivores

    OpenAIRE

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2015-01-01

    Abstract Diet analysis is an important aspect when investigating the ecology of fish?eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time?consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two?step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection o...

  18. Estimating the Population Size and Genetic Diversity of Amur Tigers in Northeast China.

    Directory of Open Access Journals (Sweden)

    Hailong Dou

    Full Text Available Over the past century, the endangered Amur tiger (Panthera tigris altaica has experienced a severe contraction in demography and geographic range because of habitat loss, poaching, and prey depletion. In its historical home in Northeast China, there appears to be a single tiger population that includes tigers in Southwest Primorye and Northeast China; however, the current demographic status of this population is uncertain. Information on the abundance, distribution and genetic diversity of this population for assessing the efficacy of conservation interventions are scarce. We used noninvasive genetic detection data from scats, capture-recapture models and an accumulation curve method to estimate the abundance of Amur tigers in Northeast China. We identified 11 individual tigers (6 females and 5 males using 10 microsatellite loci in three nature reserves between April 2013 and May 2015. These tigers are confined primarily to a Hunchun Nature Reserve along the border with Russia, with an estimated population abundance of 9-11 tigers during the winter of 2014-2015. They showed a low level of genetic diversity. The mean number of alleles per locus was 2.60 and expected and observed heterozygosity were 0.42 and 0.49, respectively. We also documented long-distance dispersal (~270 km of a male Amur tiger to Huangnihe Nature Reserve from the border, suggesting that the expansion of neighboring Russian populations may eventually help sustain Chinese populations. However, the small and isolated population recorded by this study demonstrate that there is an urgent need for more intensive regional management to create a tiger-permeable landscape and increased genetic connectivity with other populations.

  19. Estimating the Population Size and Genetic Diversity of Amur Tigers in Northeast China.

    Science.gov (United States)

    Dou, Hailong; Yang, Haitao; Feng, Limin; Mou, Pu; Wang, Tianming; Ge, Jianping

    2016-01-01

    Over the past century, the endangered Amur tiger (Panthera tigris altaica) has experienced a severe contraction in demography and geographic range because of habitat loss, poaching, and prey depletion. In its historical home in Northeast China, there appears to be a single tiger population that includes tigers in Southwest Primorye and Northeast China; however, the current demographic status of this population is uncertain. Information on the abundance, distribution and genetic diversity of this population for assessing the efficacy of conservation interventions are scarce. We used noninvasive genetic detection data from scats, capture-recapture models and an accumulation curve method to estimate the abundance of Amur tigers in Northeast China. We identified 11 individual tigers (6 females and 5 males) using 10 microsatellite loci in three nature reserves between April 2013 and May 2015. These tigers are confined primarily to a Hunchun Nature Reserve along the border with Russia, with an estimated population abundance of 9-11 tigers during the winter of 2014-2015. They showed a low level of genetic diversity. The mean number of alleles per locus was 2.60 and expected and observed heterozygosity were 0.42 and 0.49, respectively. We also documented long-distance dispersal (~270 km) of a male Amur tiger to Huangnihe Nature Reserve from the border, suggesting that the expansion of neighboring Russian populations may eventually help sustain Chinese populations. However, the small and isolated population recorded by this study demonstrate that there is an urgent need for more intensive regional management to create a tiger-permeable landscape and increased genetic connectivity with other populations.

  20. Infomechanical specializations for prey capture in knifefish

    Science.gov (United States)

    Maciver, Malcolm; Patankar, Neelesh; Curet, Oscar; Shirgaonkar, Anup

    2007-11-01

    How does an animal's mechanics and its information acquisition system work together to solve crucial behavioral tasks? We examine this question for the black ghost weakly electric knifefish (Apteronotus albifrons), which is a leading model system for the study of sensory processing in vertebrates. These animals hunt at night by detecting perturbations of a self-generated electric field caused by prey. While the fish searches for prey, it pitches at 30 . Fully resolved Navier-Stokes simulations of their swimming, which occurs through undulations of a long ribbon-like fin along the bottom edge of the body, indicates that this configuration enables maximal thrust while minimizing pitch moment. However, pitching the body also increases drag. Our analysis of the sensory volume for detection of prey shows this volume to be similar to a cylinder around the body. Thus, pitching the body enables a greater swept volume of scanned fluid. Examining the mechanical and information acquisition demands on the animal in this task gives insight into how these sometimes conflicting demands are resolved.

  1. Prey-predator dynamics with prey refuge providing additional food to predator

    International Nuclear Information System (INIS)

    Ghosh, Joydev; Sahoo, Banshidhar; Poria, Swarup

    2017-01-01

    Highlights: • The effects of interplay between prey refugia and additional food are reported. • Hopf bifurcation conditions are derived analytically. • Existence of unique limit cycle is shown analytically. • Predator extinction may be possible at very high prey refuge ecological systems. - Abstract: The impacts of additional food for predator on the dynamics of a prey-predator model with prey refuge are investigated. The equilibrium points and their stability behaviours are determined. Hopf bifurcation conditions are derived analytically. Most significantly, existence conditions for unique stable limit cycle in the phase plane are shown analytically. The analytical results are in well agreement with the numerical simulation results. Effects of variation of refuge level as well as the variation of quality and quantity of additional food on the dynamics are reported with the help of bifurcation diagrams. It is found that high quality and high quantity of additional food supports oscillatory coexistence of species. It is observed that predator extinction possibility in high prey refuge ecological systems may be removed by supplying additional food to predator population. The reported theoretical results may be useful to conservation biologist for species conservation in real world ecological systems.

  2. Prey preferences and prey acceptance in juvenile Brown Treesnakes (Boiga irregularis)

    Science.gov (United States)

    Lardner, Bjorn; Savidge, Julie A.; Rodda, Gordon H.; Reed, Robert N.

    2009-01-01

    On the Pacific island of Guam, control of the invasive Brown Treesnake (Boiga irregularis) relies largely on methods that use mice as bait. Juvenile B. irregularis feed primarily on lizards and their eggs, but little is known about their prey preference. We conducted an experiment to investigate preferences for, and acceptance of, dead geckos, skinks, and neonatal mice, in juvenile B. irregularis ranging from 290 mm to ca. 700 mm snout-vent length (SVL). Snakes of all sizes showed a preference for geckos over skinks and neonatal mice. Geckos were the first prey chosen in 87% of 224 initial trials (56 snakes subjected to four trials each; 33% would be expected from a random choice). The smallest snakes had the most pronounced preference. Although many of the snakes accepted neonatal mice and/or skinks, some snakes of all sizes were reluctant to feed on anything but geckos, especially when well fed. We also addressed the hypothesis that repeated encounters with a particular prey type increase a snake's preference for that prey. Our study does not support this hypothesis. Our results suggest that control methods relying solely on rodent bait may be inefficient for targeting snakes < 700 mm SVL and that individual heterogeneity in prey preference may cause a significant part of this juvenile cohort to be completely refractory to capture with rodent bait, even if the bait is dead and small enough to be readily swallowed.

  3. The East Midlands in 2006: the demography of the East Midlands

    OpenAIRE

    Lawton, C

    2006-01-01

    The East Midlands in 2006 is the evidence base that was produced to underpin the devleopment of the regional economic strategy, A Flourishing Region. This document presents detailed analysis of the demography of the East Midlands.

  4. Outrun or Outmaneuver: Predator-Prey Interactions as a Model System for Integrating Biomechanical Studies in a Broader Ecological and Evolutionary Context.

    Science.gov (United States)

    Moore, Talia Y; Biewener, Andrew A

    2015-12-01

    Behavioral studies performed in natural habitats provide a context for the development of hypotheses and the design of experiments relevant both to biomechanics and to evolution. In particular, predator-prey interactions are a model system for integrative study because success or failure of predation has a direct effect on fitness and drives the evolution of specialized performance in both predator and prey. Although all predators share the goal of capturing prey, and all prey share the goal of survival, the behavior of predators and prey are diverse in nature. This article presents studies of some predator-prey interactions sharing common predation strategies that reveal general principles governing the behaviors of predator and prey, even in distantly related taxa. Studies of predator-prey interactions also reveal that maximal performance observed in a laboratory setting is not necessarily the performance that determines fitness. Thus, considering locomotion in the context of predation ecology can aid in evolutionarily relevant experimental design. Classification by strategy reveals that displaying unpredictable trajectories is a relevant anti-predator behavior in response to multiple predation strategies. A predator's perception and pursuit of prey can be affected indirectly by divergent locomotion of similar animals that share an ecosystem. Variation in speed and direction of locomotion that directly increases the unpredictability of a prey's trajectory can be increased through genetic mutation that affects locomotor patterns, musculoskeletal changes that affect maneuverability, and physical interactions between an animal and the environment. By considering the interconnectedness of ecology, physical constraints, and the evolutionary history of behavior, studies in biomechanics can be designed to inform each of these fields. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights

  5. The implications of environmental variability on caribou demography: theoretical considerations

    Directory of Open Access Journals (Sweden)

    James A. Schaefer

    1991-10-01

    Full Text Available Random environmental influences, such as snow cover, are widely regarded as an integral feature of caribou population dynamics. We conducted computer simulations to explore the ramifications of such stochastic variability for caribou demography. We devised 4 models with increasing levels of complexity: Model 1, density-independence under different levels of stochasticity and r; Model 2, non-linear effect of snow cover on r; Model 3, non-linear effect of snow cover on r and stochasticity as a function of population size; and Model 4, non-linear effect of snow cover on r, stochasticity as a funciton of population size, and density-dependence according to the logistic equation. The results of Model 1 indicated that nearly all caribou populations subject only to environmental vagaries experienced either extincition or irruption. Model 2 revealed that non-linear effect of snow cover depressed the realised r as a function of population size. Finally, Model 4 suggested long-term population as previously reported in literature, but with reduced chance of overshooting K under moderate to high environmental variability.

  6. Land use and demography survey for a large superfund site

    International Nuclear Information System (INIS)

    Hattemer-Frey, H.A.; Quinlan, R.E.; Krieger, G.R.; Lau, V.

    1994-01-01

    Inconsistencies in the exposure assessment process often arise when risk assessors are forced to make assumptions about the frequency and duration of exposures in the absence of site-specific data. EPA encourages the collection of site-specific data so that risks can be more accurately assessed on a case-by-case basis. Typically, estimates of exposure frequency and duration represent the largest source of uncertainty for non-food related exposure pathways, while the largest source of uncertainty for foodchain pathways stems primarily from estimating the fraction ingested that originated from the affected area. A Land Use and Demography Survey was conducted to obtain site-specific information on: (1) the amount of time individuals spend indoors, outdoors, and on or near affected areas; (2) recreational use of surface water bodies on-site; (3) the percentage of food items consumed that were raised or produced locally; and (4) other behavioral patterns and activities that could influence their exposure to site-related chemicals. More than 300 households were randomly selected and the residents personally interviewed. A wide variety of individuals ranging from children to elderly residents with vastly different recreational, behavioral, and consumption patterns were interviewed. This paper discusses the survey results in relation to EPA standard default exposure assumptions

  7. Culture and Demography: From Reluctant Bedfellows to Committed Partners

    Science.gov (United States)

    Bachrach, Christine A.

    2015-01-01

    Demography and culture have had a long but ambivalent relationship. Cultural influences are widely recognized as important for demographic outcomes, but are often “backgrounded” in demographic research. I argue that progress towards a more successful integration is feasible and suggest a network model of culture as a potential tool. The network model bridges both traditional (holistic and institutional) and contemporary (tool kit) models of culture used in the social sciences and offers a simple vocabulary for the diverse set of cultural concepts such as attitudes, beliefs and norms, and quantitative measures of how culture is organized. The proposed model conceptualizes culture as a nested network of meanings which are represented by schemas that range in complexity from simple concepts to multifaceted cultural models. I illustrate the potential value of a model using accounts of the cultural changes underpinning the transformation of marriage in the U.S. and point to developments in the social, cognitive and computational sciences that could facilitate the application of the model in empirical demographic research. PMID:24338643

  8. Matrix dimensions bias demographic inferences: implications for comparative plant demography.

    Science.gov (United States)

    Salguero-Gómez, Roberto; Plotkin, Joshua B

    2010-12-01

    While the wealth of projection matrices in plant demography permits comparative studies, variation in matrix dimensions complicates interspecific comparisons. Collapsing matrices to a common dimension may facilitate such comparisons but may also bias the inferred demographic parameters. Here we examine how matrix dimension affects inferred demographic elasticities and how different collapsing criteria perform. We analyzed 13 x 13 matrices representing nine plant species, collapsing these matrices (i) into even 7 x 7, 5 x 5, 4 x 4, and 3 x 3 matrices and (ii) into 5 x 5 matrices using different criteria. Stasis and fecundity elasticities increased when matrix dimension was reduced, whereas those of progression and retrogression decreased. We suggest a collapsing criterion that minimizes dissimilarities between the original- and collapsed-matrix elasticities and apply it to 66 plant species to study how life span and growth form influence the relationship between matrix dimension and elasticities. Our analysis demonstrates that (i) projection matrix dimension has significant effects on inferred demographic parameters, (ii) there are better-performing methods than previously suggested for standardizing matrix dimension, and (iii) herbaceous perennial projection matrices are particularly sensitive to changes in matrix dimensionality. For comparative demographic studies, we recommend normalizing matrices to a common dimension by collapsing higher classes and leaving the first few classes unaltered.

  9. Behavioural and physiological responses of limpet prey to a seastar predator and their transmission to basal trophic levels.

    Science.gov (United States)

    Manzur, Tatiana; Vidal, Francisco; Pantoja, José F; Fernández, Miriam; Navarrete, Sergio A

    2014-07-01

    Besides the well-documented behavioural changes induced by predators on prey, predator-induced stress can also include a suite of biochemical, neurological and metabolic changes that may represent important energetic costs and have long-lasting effects on individuals and on the demography of prey populations. The rapid transmission of prey behavioural changes to lower trophic levels, usually associated with alteration of feeding rates, can substantially change and even reverse direction over the long term as prey cope with the energetic costs associated with predation-induced stress. It is therefore critical to evaluate different aspects and assess the costs of non-consumptive predator effects on prey. We investigated the behavioural and physiological responses of an herbivorous limpet, Fissurella limbata, to the presence of chemical cues and direct non-lethal contact by the common seastar predator, Heliaster helianthus. We also evaluated whether the limpets feeding behaviour was modified by the predator and whether this translated into positive or negative effects on biomass of the green alga, Ulva sp. Our experimental results show the presence of Heliaster led to increased movement activity, increased distances travelled, changes in time budget over different environmental conditions and increased feeding rate in the keyhole limpets. Moreover, additional experiments showed that, beyond the increased metabolic rate associated with limpet increased activity, predator chemical cues heighten metabolic rate as part of the induced stress response. Changes in individual movement and displacement distances observed through the 9-day experiment can be interpreted as part of the escape response exhibited by limpets to reduce the risk of being captured by the predator. Increased limpet feeding rate on algae can be visualized as a way individuals compensate for the elevated energetic costs of movement and heightened metabolic rates produced by the predator-induced stress

  10. Deep Learning for Population Genetic Inference.

    Science.gov (United States)

    Sheehan, Sara; Song, Yun S

    2016-03-01

    Given genomic variation data from multiple individuals, computing the likelihood of complex population genetic models is often infeasible. To circumvent this problem, we introduce a novel likelihood-free inference framework by applying deep learning, a powerful modern technique in machine learning. Deep learning makes use of multilayer neural networks to learn a feature-based function from the input (e.g., hundreds of correlated summary statistics of data) to the output (e.g., population genetic parameters of interest). We demonstrate that deep learning can be effectively employed for population genetic inference and learning informative features of data. As a concrete application, we focus on the challenging problem of jointly inferring natural selection and demography (in the form of a population size change history). Our method is able to separate the global nature of demography from the local nature of selection, without sequential steps for these two factors. Studying demography and selection jointly is motivated by Drosophila, where pervasive selection confounds demographic analysis. We apply our method to 197 African Drosophila melanogaster genomes from Zambia to infer both their overall demography, and regions of their genome under selection. We find many regions of the genome that have experienced hard sweeps, and fewer under selection on standing variation (soft sweep) or balancing selection. Interestingly, we find that soft sweeps and balancing selection occur more frequently closer to the centromere of each chromosome. In addition, our demographic inference suggests that previously estimated bottlenecks for African Drosophila melanogaster are too extreme.

  11. Deep Learning for Population Genetic Inference.

    Directory of Open Access Journals (Sweden)

    Sara Sheehan

    2016-03-01

    Full Text Available Given genomic variation data from multiple individuals, computing the likelihood of complex population genetic models is often infeasible. To circumvent this problem, we introduce a novel likelihood-free inference framework by applying deep learning, a powerful modern technique in machine learning. Deep learning makes use of multilayer neural networks to learn a feature-based function from the input (e.g., hundreds of correlated summary statistics of data to the output (e.g., population genetic parameters of interest. We demonstrate that deep learning can be effectively employed for population genetic inference and learning informative features of data. As a concrete application, we focus on the challenging problem of jointly inferring natural selection and demography (in the form of a population size change history. Our method is able to separate the global nature of demography from the local nature of selection, without sequential steps for these two factors. Studying demography and selection jointly is motivated by Drosophila, where pervasive selection confounds demographic analysis. We apply our method to 197 African Drosophila melanogaster genomes from Zambia to infer both their overall demography, and regions of their genome under selection. We find many regions of the genome that have experienced hard sweeps, and fewer under selection on standing variation (soft sweep or balancing selection. Interestingly, we find that soft sweeps and balancing selection occur more frequently closer to the centromere of each chromosome. In addition, our demographic inference suggests that previously estimated bottlenecks for African Drosophila melanogaster are too extreme.

  12. Deep Learning for Population Genetic Inference

    Science.gov (United States)

    Sheehan, Sara; Song, Yun S.

    2016-01-01

    Given genomic variation data from multiple individuals, computing the likelihood of complex population genetic models is often infeasible. To circumvent this problem, we introduce a novel likelihood-free inference framework by applying deep learning, a powerful modern technique in machine learning. Deep learning makes use of multilayer neural networks to learn a feature-based function from the input (e.g., hundreds of correlated summary statistics of data) to the output (e.g., population genetic parameters of interest). We demonstrate that deep learning can be effectively employed for population genetic inference and learning informative features of data. As a concrete application, we focus on the challenging problem of jointly inferring natural selection and demography (in the form of a population size change history). Our method is able to separate the global nature of demography from the local nature of selection, without sequential steps for these two factors. Studying demography and selection jointly is motivated by Drosophila, where pervasive selection confounds demographic analysis. We apply our method to 197 African Drosophila melanogaster genomes from Zambia to infer both their overall demography, and regions of their genome under selection. We find many regions of the genome that have experienced hard sweeps, and fewer under selection on standing variation (soft sweep) or balancing selection. Interestingly, we find that soft sweeps and balancing selection occur more frequently closer to the centromere of each chromosome. In addition, our demographic inference suggests that previously estimated bottlenecks for African Drosophila melanogaster are too extreme. PMID:27018908

  13. Prey selectivity affects reproductive success of a corallivorous reef fish.

    Science.gov (United States)

    Brooker, Rohan M; Jones, Geoffrey P; Munday, Philip L

    2013-06-01

    Most animals consume a narrower range of food resources than is potentially available in the environment, but the underlying basis for these preferences is often poorly understood. Foraging theory predicts that prey selection should represent a trade-off between prey preferences based on nutritional value and prey availability. That is, species should consume preferred prey when available, but select less preferred prey when preferred prey is rare. We employed both field observation and laboratory experiments to examine the relationship between prey selection and preferences in the obligate coral-feeding filefish, Oxymonacanthus longirostris. To determine the drivers of prey selection, we experimentally established prey preferences in choice arenas and tested the consequences of prey preferences for key fitness-related parameters. Field studies showed that individuals fed almost exclusively on live corals from the genus Acropora. While diet was dominated by the most abundant species, Acropora nobilis, fish appeared to preferentially select rarer acroporids, such as A. millepora and A. hyacinthus. Prey choice experiments confirmed strong preferences for these corals, suggesting that field consumption is constrained by availability. In a longer-term feeding experiment, reproductive pairs fed on non-preferred corals exhibited dramatic reductions to body weight, and in hepatic and gonad condition, compared with those fed preferred corals. The majority of pairs fed preferred corals spawned frequently, while no spawning was observed for any pairs fed a non-preferred species of coral. These experiments suggest that fish distinguish between available corals based on their intrinsic value as prey, that reproductive success is dependent on the presence of particular coral species, and that differential loss of preferred corals could have serious consequences for the population success of these dietary specialists.

  14. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Directory of Open Access Journals (Sweden)

    Håkan Sand

    Full Text Available Research on large predator-prey interactions are often limited to the predators' primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces and one small-sized ungulate; roe deer (Capreolus capreolus. Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves' choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population.

  15. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Science.gov (United States)

    Eklund, Ann; Zimmermann, Barbara; Wikenros, Camilla; Wabakken, Petter

    2016-01-01

    Research on large predator-prey interactions are often limited to the predators’ primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus) prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces) and one small-sized ungulate; roe deer (Capreolus capreolus). Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves’ choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population. PMID:28030549

  16. Prey Selection of Scandinavian Wolves: Single Large or Several Small?

    Science.gov (United States)

    Sand, Håkan; Eklund, Ann; Zimmermann, Barbara; Wikenros, Camilla; Wabakken, Petter

    2016-01-01

    Research on large predator-prey interactions are often limited to the predators' primary prey, with the potential for prey switching in systems with multiple ungulate species rarely investigated. We evaluated wolf (Canis lupus) prey selection at two different spatial scales, i.e., inter- and intra-territorial, using data from 409 ungulate wolf-kills in an expanding wolf population in Scandinavia. This expansion includes a change from a one-prey into a two-prey system with variable densities of one large-sized ungulate; moose (Alces alces) and one small-sized ungulate; roe deer (Capreolus capreolus). Among wolf territories, the proportion of roe deer in wolf kills was related to both pack size and roe deer density, but not to moose density. Pairs of wolves killed a higher proportion of roe deer than did packs, and wolves switched to kill more roe deer as their density increased above a 1:1 ratio in relation to the availability of the two species. At the intra-territorial level, wolves again responded to changes in roe deer density in their prey selection whereas we found no effect of snow depth, time during winter, or other predator-related factors on the wolves' choice to kill moose or roe deer. Moose population density was only weakly related to intra-territorial prey selection. Our results show that the functional response of wolves on moose, the species hitherto considered as the main prey, was strongly dependent on the density of a smaller, alternative, ungulate prey. The impact of wolf predation on the prey species community is therefore likely to change with the composition of the multi-prey species community along with the geographical expansion of the wolf population.

  17. Molecular prey identification in Central European piscivores.

    Science.gov (United States)

    Thalinger, Bettina; Oehm, Johannes; Mayr, Hannes; Obwexer, Armin; Zeisler, Christiane; Traugott, Michael

    2016-01-01

    Diet analysis is an important aspect when investigating the ecology of fish-eating animals and essential for assessing their functional role in food webs across aquatic and terrestrial ecosystems. The identification of fish remains in dietary samples, however, can be time-consuming and unsatisfying using conventional morphological analysis of prey remains. Here, we present a two-step multiplex PCR system, comprised of six assays, allowing for rapid, sensitive and specific detection of fish DNA in dietary samples. This approach encompasses 78 fish and lamprey species native to Central European freshwaters and enables the identification of 31 species, six genera, two families, two orders and two fish family clusters. All targeted taxa were successfully amplified from 25 template molecules, and each assay was specific when tested against a wide range of invertebrates and vertebrates inhabiting aquatic environments. The applicability of the multiplex PCR system was evaluated in a feeding trial, wherein it outperformed morphological prey analysis regarding species-specific prey identification in faeces of Eurasian otters. Additionally, a wide spectrum of fish species was detected in field-collected faecal samples and regurgitated pellets of Common Kingfishers and Great Cormorants, demonstrating the broad applicability of the approach. In conclusion, this multiplex PCR system provides an efficient, easy to use and cost-effective tool for assessing the trophic ecology of piscivores in Central Europe. Furthermore, the multiplex PCRs and the primers described therein will be applicable wherever DNA of the targeted fish species needs to be detected at high sensitivity and specificity. © 2015 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

  18. Hepatozoon infection prevalence in four snake genera: influence of diet, prey parasitemia levels, or parasite type?

    Science.gov (United States)

    Tomé, Beatriz; Maia, João P M C; Harris, D James

    2012-10-01

    Hepatozoon spp. (Apicomplexa: Haemogregarinidae) are the most commonly reported hemoparasites from snakes. Of over 300 Hepatozoon species identified, more than 120 were described from snakes. However, recent genetic assessments have found Hepatozoon lineages recovered from both prey and predators, indicating that diet may play an important role in the infection of final vertebrate hosts. Here 4 different snake genera with different diets were assessed. Hepatozoon spp. prevalence varied greatly between the genera, but only lineages already identified from potential prey, i.e., gecko and lacertid lizards, were recovered from the snakes. Interestingly, the Hepatozoon spp. lineage known from geckos was the most common in the snakes, but this does not reflect their diet. Higher parasitemia levels, reported for some geckos relative to lacertid lizards, may play a role. Alternatively, this lineage may be more effective at parasitizing snakes or may occur, despite being unrecorded, in other vertebrate groups consumed by snakes.

  19. Predator-prey interactions of nematode-trapping fungi and nematodes: both sides of the coin.

    Science.gov (United States)

    Vidal-Diez de Ulzurrun, Guillermo; Hsueh, Yen-Ping

    2018-05-01

    Nematode-trapping fungi develop complex trapping devices to capture and consume nematodes. The dynamics of these organisms is especially important given the pathogenicity of nematodes and, consequently, the potential application of nematode-trapping fungi as biocontrol agents. Furthermore, both the nematodes and nematode-trapping fungi can be easily grown in laboratories, making them a unique manipulatable predator-prey system to study their coevolution. Several different aspects of these fungi have been studied, such as their genetics and the different factors triggering trap formation. In this review, we use the nematode-trapping fungus Arthrobotrys oligospora (which forms adhesive nets) as a model to describe the trapping process. We divide this process into several stages; namely attraction, recognition, trap formation, adhesion, penetration, and digestion. We summarize the latest findings in the field and current knowledge on the interactions between nematodes and nematode-trapping fungi, representing both sides of the predator-prey interaction.

  20. Stochastic Predator-Prey Dynamics of Transposons in the Human Genome

    Science.gov (United States)

    Xue, Chi; Goldenfeld, Nigel

    2016-11-01

    Transposable elements, or transposons, are DNA sequences that can jump from site to site in the genome during the life cycle of a cell, usually encoding the very enzymes which perform their excision. However, some transposons are parasitic, relying on the enzymes produced by the regular transposons. In this case, we show that a stochastic model, which takes into account the small copy numbers of the active transposons in a cell, predicts noise-induced predator-prey oscillations with a characteristic time scale that is much longer than the cell replication time, indicating that the state of the predator-prey oscillator is stored in the genome and transmitted to successive generations. Our work demonstrates the important role of the number fluctuations in the expression of mobile genetic elements, and shows explicitly how ecological concepts can be applied to the dynamics and fluctuations of living genomes.

  1. Limit Cycles in Predator-Prey Models

    OpenAIRE

    Puchuri Medina, Liliana

    2017-01-01

    The classic Lotka-Volterra model belongs to a family of differential equations known as “Generalized Lotka-Volterra”, which is part of a classification of four models of quadratic fields with center. These models have been studied to address the Hilbert infinitesimal problem, which consists in determine the number of limit cycles of a perturbed hamiltonian system with center. In this work, we first present an alternative proof of the existence of centers in Lotka-Volterra predator-prey models...

  2. Assassin bug uses aggressive mimicry to lure spider prey.

    Science.gov (United States)

    Wignall, Anne E; Taylor, Phillip W

    2011-05-07

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'.

  3. Behavior of prey links midwater and demersal piscivorous reef fishes

    Directory of Open Access Journals (Sweden)

    Peter J. Auster

    Full Text Available Pelagic and demersal guilds of piscivorous fishes are linked by a variety of biological and physical processes that mediate interactions with common prey species. Understanding the behaviors of predators and prey can provide insight into the conditions that make such linkages possible. Here we report on the behaviors of mid-water piscivorous fishes and the responses of prey that produce feeding opportunities for demersal piscivorous fishes associated with "live bottom" ledge habitats off the coast of Georgia (northwest Atlantic Ocean. Prey taxa reduced nearest neighbor distances and retreated towards the seafloor during predatory attacks by mid-water fishes. Demersal fishes subsequently attacked and consumed prey in these ephemeral high density patches. No predation by demersal fishes was observed when prey species were at background densities. If the predator-prey interactions of demersal piscivorous fishes are commonly mediated by the predatory behavior of midwater piscivorous fishes and their prey, such indirect facilitative behaviors may be important in terms of the population processes (e.g., prey consumption and growth rates of these demersal fishes.

  4. Rapid prey evolution can alter the structure of predator-prey communities

    NARCIS (Netherlands)

    Friman, V. -P.; Jousset, A.; Buckling, A.

    Although microevolution has been shown to play an important role in pairwise antagonistic species interactions, its importance in more complex communities has received little attention. Here, we used two Pseudomonas fluorescens prey bacterial strains (SBW25 and F113) and Tetrahymena thermophila

  5. Coexistence for an Almost Periodic Predator-Prey Model with Intermittent Predation Driven by Discontinuous Prey Dispersal

    Directory of Open Access Journals (Sweden)

    Yantao Luo

    2017-01-01

    Full Text Available An almost periodic predator-prey model with intermittent predation and prey discontinuous dispersal is studied in this paper, which differs from the classical continuous and impulsive dispersal predator-prey models. The intermittent predation behavior of the predator species only happens in the channels between two patches where the discontinuous migration movement of the prey species occurs. Using analytic approaches and comparison theorems of the impulsive differential equations, sufficient criteria on the boundedness, permanence, and coexistence for this system are established. Finally, numerical simulations demonstrate that, for an intermittent predator-prey model, both the intermittent predation and intrinsic growth rates of the prey and predator species can greatly impact the permanence, extinction, and coexistence of the population.

  6. The Coevolution of "Tyrannosaurus" & Its Prey: Could "Tyrannosaurus" Chase down & Kill a "Triceratops" for Lunch?

    Science.gov (United States)

    May, S. Randolph

    2014-01-01

    Students will analyze the coevolution of the predator-prey relationships between "Tyrannosaurus rex" and its prey species using analyses of animal speeds from fossilized trackways, prey-animal armaments, adaptive behaviors, bite marks on prey-animal fossils, predator-prey ratios, and scavenger competition. The students will be asked to…

  7. Diet choice of a predator in the wild: overabundance of prey and missed opportunities along the prey capture sequence

    OpenAIRE

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2012-01-01

    Optimal diet theory (ODT) postulates that predators adjust their foraging decisions by calculating a prey value from the potential biomass gain, handling time, prey vulnerability and encounter rate. Tests of ODT have however so far mainly been restricted to laboratory settings. By video surveillance, we gathered a large data set of more than 2000 field observations of crab spider (Misumena vatia) encounters with potential prey. We then tested whether the complex ODT or two simpler models (pre...

  8. Feeding rates in the chaetognath Sagitta elegans : effects of prey size, prey swimming behaviour and small-scale turbulence

    DEFF Research Database (Denmark)

    Saito, H.; Kiørboe, Thomas

    2001-01-01

    distances. We develop a simple prey encounter rate model by describing the swimming prey as a 'force dipole' and assuming that a critical signal strength is required to elicit an attack. By fitting the model to the observations, a critical signal strength of 10(-2) cm s(-1) is estimated; this is very...... at rates up to an order of magnitude higher than similarly sized females, probably owing to differences in swimming behaviour. Sagitta elegans is an ambush predator that perceives its prey by hydromechanical signals. Faster swimming prey generates stronger signals and is, hence, perceived at longer...

  9. Snowscape Ecology: Linking Snow Properties to Wildlife Movements and Demography

    Science.gov (United States)

    Prugh, L.; Verbyla, D.; van de Kerk, M.; Mahoney, P.; Sivy, K. J.; Liston, G. E.; Nolin, A. W.

    2017-12-01

    Snow enshrouds up to one third of the global land mass annually and exerts a major influence on animals that reside in these "snowscapes," (landscapes covered in snow). Dynamic snowscapes may have especially strong effects in arctic and boreal regions where dry snow persists for much of the year. Changes in temperature and hydrology are transforming northern regions, with profound implications for wildlife that are not well understood. We report initial findings from a NASA ABoVE project examining effects of snow properties on Dall sheep (Ovis dalli dalli). We used the MODSCAG snow fraction product to map spring snowline elevations and snow-off dates from 2000-2015 throughout the global range of Dall sheep in Alaska and northwestern Canada. We found a negative effect of spring snow cover on Dall sheep recruitment that increased with latitude. Using meteorological data and a daily freeze/thaw status product derived from passive microwave remote sensing from 1983-2012, we found that sheep survival rates increased in years with higher temperatures, less winter precipitation, fewer spring freeze-thaw events, and more winter freeze-thaw events. To examine the effects of snow depth and density on sheep movements, we used location data from GPS-collared sheep and a snowpack evolution model (SnowModel). We found that sheep selected for shallow, fluffy snow at high elevations, but they selected for denser snow as depth increased. Our field measurements identified a critical snow density threshold of 329 (± 18 SE) kg/m3 to support the weight of Dall sheep. Thus, sheep may require areas of shallow, fluffy snow for foraging, while relying on hard-packed snow for winter travel. These findings highlight the importance of multiple snowscape properties on wildlife movements and demography. The integrated study of snow properties and ecological processes, which we call snowscape ecology, will greatly improve global change forecasting.

  10. Evaluating prey switching in wolf-ungulate systems.

    Science.gov (United States)

    Garrott, Robert A; Bruggeman, Jason E; Becker, Matthew S; Kalinowski, Steven T; White, P J

    2007-09-01

    Wolf restoration has become a widely accepted conservation and management practice throughout North America and Europe, though the ecosystem effects of returning top carnivores remain both scientific and societal controversies. Mathematical models predicting and describing wolf-ungulate interactions are typically limited to the wolves' primary prey, with the potential for prey switching in wolf-multiple-ungulate systems only suggested or assumed by a number of investigators. We used insights gained from experiments on small taxa and field data from ongoing wolf-ungulate studies to construct a model of predator diet composition for a wolf-elk-bison system in Yellowstone National Park, Wyoming, USA. The model explicitly incorporates differential vulnerability of the ungulate prey types to predation, predator preference, differences in prey biomass, and the possibility of prey switching. Our model demonstrates wolf diet shifts with changes in relative abundance of the two prey, with the dynamics of this shift dependent on the combined influences of preference, differential vulnerability, relative abundances of prey, and whether or not switching occurs. Differences in vulnerability between elk and bison, and strong wolf preference for elk, result in an abrupt dietary shift occurring only when elk are very rare relative to bison, whereas incorporating switching initiates the dietary shift more gradually and at higher bison-elk ratios. We demonstrate how researchers can apply these equations in newly restored wolf-two-prey systems to empirically evaluate whether prey switching is occurring. Each coefficient in the model has a biological interpretation, and most can be directly estimated from empirical data collected from field studies. Given the potential for switching to dramatically influence predator-prey dynamics and the wide range of expected prey types and abundances in some systems where wolves are present and/or being restored, we suggest that this is an

  11. Red fox prey demands and implications to prairie duck production

    Science.gov (United States)

    Sargeant, A.B.

    1978-01-01

    Experiments were conducted during spring and summer with 33 red foxes (Vulpes vulpes) to determine prey demands, feeding characteristics, and growth rates using natural foods. Pups began eating prey the 4th week after birth. Then, prey consumption averaged 1.38 and 1.90 kg/pup/week for weeks 5-8 and 9-12 of the denning season respectively, and 2.54 kg/pup/week for the postdenning period. Feeding by adults averaged 2.25 kg/adult/week. Free water was not needed by either pups or adults. About 90 percent of the prey offered to pups on simulated natural diets was consumed, remains varied with prey availability and prey type. Prey biomass required by a typical fox family was estimated at 18.5 kg/km2 for the 12-week denning season and 2.4 kg/km2/week for the postdenning period. Because of the large prey demands, ducks could represent a small part of the foxes' diet and yet be of consequence to the productivity of particular species. An example is provided for the mallard (Anas platyrhynchos).

  12. Determination of carnivores prey base by scat analysis in Samburu ...

    African Journals Online (AJOL)

    Administrator

    This study determined the prey base for four main carnivores found in Samburu community group ranches and ... a result of the hydrolysis of protein that acts as cement for the keratin ... prey component between predator species that may be attributed to ... causing ever-closer interaction between humans and wildlife. This is ...

  13. Stationary Patterns in One-Predator Two-Prey Models

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    1999-01-01

    Weakly-coupled elliptic system decribing models of simple three-species food webs such as the one-predator, two-prey modelis discussed. We show thatthere is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow...

  14. Stationary Patterns in One-Predator Two-Prey Models

    DEFF Research Database (Denmark)

    Pedersen, Michael; Zhigui, Lin

    1999-01-01

    Weakly-coupled elliptic system decribing models of simple three-species food webs such as the one-predator, two-prey model is discussed. We show that there is no non-constant solution if diffusions or inter-specific competitions are strong, or if the intrinsic growths of the prey are slow...

  15. Production of live prey for marine fish larvae

    OpenAIRE

    Kraul, S

    1989-01-01

    Tropical marine fish larvae vary in their requirements for live planktonic food. Selection of live prey species for culture depends on larval size and larval tolerance of water quality. This report describes some of the cultured prey species, and their uses and limits as effective food for fish larvae. Methods are presented for the culture of phytoplankton, rotifers, copepods, and other live feeds.

  16. Behavioral response races, predator-prey shell games, ecology of fear, and patch use of pumas and their ungulate prey.

    Science.gov (United States)

    Laundré, John W

    2010-10-01

    The predator-prey shell game predicts random movement of prey across the landscape, whereas the behavioral response race and landscape of fear models predict that there should be a negative relationship between the spatial distribution of a predator and its behaviorally active prey. Additionally, prey have imperfect information on the whereabouts of their predator, which the predator should incorporate in its patch use strategy. I used a one-predator-one-prey system, puma (Puma concolor)-mule deer (Odocoileus hemionus) to test the following predictions regarding predator-prey distribution and patch use by the predator. (1) Pumas will spend more time in high prey risk/low prey use habitat types, while deer will spend their time in low-risk habitats. Pumas should (2) select large forage patches more often, (3) remain in large patches longer, and (4) revisit individual large patches more often than individual smaller ones. I tested these predictions with an extensive telemetry data set collected over 16 years in a study area of patchy forested habitat. When active, pumas spent significantly less time in open areas of low intrinsic predation risk than did deer. Pumas used large patches more than expected, revisited individual large patches significantly more often than smaller ones, and stayed significantly longer in larger patches than in smaller ones. The results supported the prediction of a negative relationship in the spatial distribution of a predator and its prey and indicated that the predator is incorporating the prey's imperfect information about its presence. These results indicate a behavioral complexity on the landscape scale that can have far-reaching impacts on predator-prey interactions.

  17. Gendered Authorship and Demographic Research: An Analysis of 50 Years of Demography.

    Science.gov (United States)

    Krapf, Sandra; Kreyenfeld, Michaela; Wolf, Katharina

    2016-08-01

    Demography, the official journal of the Population Association of America, has been given the highest rating among demographic journals by the Social Sciences Citation Index (SSCI). Our aim here is to investigate the development of research subfields and female authorship in Demography over the last 50 years. We find that female authorship in Demography has risen considerably since the 1980s and that currently a woman is about as likely as a man to be the sole or the first author of a paper published in the journal. However, we find some differences by subfield. Women seem to be overrepresented in the "family and household" research subfield but underrepresented in the "mortality and health" and "data and methods" categories.

  18. Feeding, prey selection and prey encounter mechanisms in the heterotrophic dinoflagellate Noctiluca scintillans

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Titelman, J.

    1998-01-01

    /or that microscale shear brings it into contact with prey. Noctiluca scintillans has a specific carbon content 1-2 orders of magnitude less than that typical for protists and, thus, an inflated volume. It also has a density slightly less than that of the ambient water and therefore ascends at high velocities...... (similar to 1 m h(- 1)). In stagnant water, clearance rates of latex spheres (5-80 mu m) increased approximately with prey particle size squared. This scaling is consistent with N.scintillans being an interception feeder. However, absolute clearance rates were substantially lower than those predicted...... higher rates than latex beads and other phytoplankters, particularly dinoflagellates. We propose that diatoms stick more efficiently than latex beads to the mucus of N.scintillans and that dinoflagellates reduce fatal contact behaviorally. We conclude that N.scintillans is an interception feeder...

  19. COMADRE: a global data base of animal demography.

    Science.gov (United States)

    Salguero-Gómez, Roberto; Jones, Owen R; Archer, C Ruth; Bein, Christoph; de Buhr, Hendrik; Farack, Claudia; Gottschalk, Fränce; Hartmann, Alexander; Henning, Anne; Hoppe, Gabriel; Römer, Gesa; Ruoff, Tara; Sommer, Veronika; Wille, Julia; Voigt, Jakob; Zeh, Stefan; Vieregg, Dirk; Buckley, Yvonne M; Che-Castaldo, Judy; Hodgson, David; Scheuerlein, Alexander; Caswell, Hal; Vaupel, James W

    2016-03-01

    The open-data scientific philosophy is being widely adopted and proving to promote considerable progress in ecology and evolution. Open-data global data bases now exist on animal migration, species distribution, conservation status, etc. However, a gap exists for data on population dynamics spanning the rich diversity of the animal kingdom world-wide. This information is fundamental to our understanding of the conditions that have shaped variation in animal life histories and their relationships with the environment, as well as the determinants of invasion and extinction. Matrix population models (MPMs) are among the most widely used demographic tools by animal ecologists. MPMs project population dynamics based on the reproduction, survival and development of individuals in a population over their life cycle. The outputs from MPMs have direct biological interpretations, facilitating comparisons among animal species as different as Caenorhabditis elegans, Loxodonta africana and Homo sapiens. Thousands of animal demographic records exist in the form of MPMs, but they are dispersed throughout the literature, rendering comparative analyses difficult. Here, we introduce the COMADRE Animal Matrix Database, an open-data online repository, which in its version 1.0.0 contains data on 345 species world-wide, from 402 studies with a total of 1625 population projection matrices. COMADRE also contains ancillary information (e.g. ecoregion, taxonomy, biogeography, etc.) that facilitates interpretation of the numerous demographic metrics that can be derived from its MPMs. We provide R code to some of these examples. We introduce the COMADRE Animal Matrix Database, a resource for animal demography. Its open-data nature, together with its ancillary information, will facilitate comparative analysis, as will the growing availability of databases focusing on other aspects of the rich animal diversity, and tools to query and combine them. Through future frequent updates of COMADRE, and

  20. Functional responses of human hunters to their prey - why harvest statistics may not always reflect changes in prey population abundance

    DEFF Research Database (Denmark)

    Kahlert, Johnny Abildgaard; Fox, Anthony David; Heldbjerg, Henning

    pigeon Columba palumbus, coot Fulica atra, grey partridge Perdix perdix, roe deer Capreolus capreolus and brown hare Lepus europaeus in Denmark. If we consider hunting a form of predator-prey interaction, the annual kill can be viewed as a predator functional response to prey population size. Convergence...

  1. Harvesting policy for a delayed stage-structured Holling II predator-prey model with impulsive stocking prey

    International Nuclear Information System (INIS)

    Jiao Jianjun; Meng Xinzhu; Chen Lansun

    2009-01-01

    A predator-prey model with a stage structure for the predator, which improves the assumption that each individual predator has the same ability to capture prey, is proposed by Wang et al. [Wang W, Mulone G, Salemi F, Salone V. Permanence and stability of a stage-structured predator-prey model. J Math Anal Appl 2001;262:499-528]. It is assumed that immature individuals and mature individuals of the predator are divided by a fixed age and that immature predators do not have the ability to attack prey. We do economic management behavior for Wang model [Wang et al., 2001] by continuous harvesting on predator and impulsive stocking on prey. Then, a delayed stage-structured Holling type II predator-prey model with impulsive stocking prey and continuous harvesting predator is established. It is also assumed that the predating products of the predator is only to increase its bearing ability. We obtain the sufficient conditions of the global attractivity of predator-extinction boundary periodic solution and the permanence of the system. Our results show that the behavior of impulsive stocking prey plays an important role for the permanence of the system, and provide tactical basis for the biological resource management. Further, the numerical analysis is also inserted to illuminate the dynamics of the system.

  2. Prey risk allocation in a grazing ecosystem.

    Science.gov (United States)

    Gude, Justin A; Garrott, Robert A; Borkowski, John J; King, Fred

    2006-02-01

    Understanding the behaviorally mediated indirect effects of predators in ecosystems requires knowledge of predator-prey behavioral interactions. In predator-ungulate-plant systems, empirical research quantifying how predators affect ungulate group sizes and distribution, in the context of other influential variables, is particularly needed. The risk allocation hypothesis proposes that prey behavioral responses to predation risk depend on background frequencies of exposure to risk, and it can be used to make predictions about predator-ungulate-plant interactions. We determined non-predation variables that affect elk (Cervus elaphus) group sizes and distribution on a winter range in the Greater Yellowstone Ecosystem (GYE) using logistic and log-linear regression on surveys of 513 1-km2 areas conducted over two years. Employing model selection techniques, we evaluated risk allocation and other a priori hypotheses of elk group size and distributional responses to wolf (Canis lupus) predation risk while accounting for influential non-wolf-predation variables. We found little evidence that wolves affect elk group sizes, which were strongly influenced by habitat type and hunting by humans. Following predictions from the risk allocation hypothesis, wolves likely created a more dynamic elk distribution in areas that they frequently hunted, as elk tended to move following wolf encounters in those areas. This response should dilute elk foraging pressure on plant communities in areas where they are frequently hunted by wolves. We predict that this should decrease the spatial heterogeneity of elk impacts on grasslands in areas that wolves frequently hunt. We also predict that this should decrease browsing pressure on heavily browsed woody plant stands in certain areas, which is supported by recent research in the GYE.

  3. Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon.

    Directory of Open Access Journals (Sweden)

    Rob Williams

    Full Text Available Ecosystem-based management (EBM of marine resources attempts to conserve interacting species. In contrast to single-species fisheries management, EBM aims to identify and resolve conflicting objectives for different species. Such a conflict may be emerging in the northeastern Pacific for southern resident killer whales (Orcinus orca and their primary prey, Chinook salmon (Oncorhynchus tshawytscha. Both species have at-risk conservation status and transboundary (Canada-US ranges. We modeled individual killer whale prey requirements from feeding and growth records of captive killer whales and morphometric data from historic live-capture fishery and whaling records worldwide. The models, combined with caloric value of salmon, and demographic and diet data for wild killer whales, allow us to predict salmon quantities needed to maintain and recover this killer whale population, which numbered 87 individuals in 2009. Our analyses provide new information on cost of lactation and new parameter estimates for other killer whale populations globally. Prey requirements of southern resident killer whales are difficult to reconcile with fisheries and conservation objectives for Chinook salmon, because the number of fish required is large relative to annual returns and fishery catches. For instance, a U.S. recovery goal (2.3% annual population growth of killer whales over 28 years implies a 75% increase in energetic requirements. Reducing salmon fisheries may serve as a temporary mitigation measure to allow time for management actions to improve salmon productivity to take effect. As ecosystem-based fishery management becomes more prevalent, trade-offs between conservation objectives for predators and prey will become increasingly necessary. Our approach offers scenarios to compare relative influence of various sources of uncertainty on the resulting consumption estimates to prioritise future research efforts, and a general approach for assessing the extent of

  4. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

    Science.gov (United States)

    Clare, Elizabeth L; Holderied, Marc W

    2015-09-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism.

  5. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

    Science.gov (United States)

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  6. Form of an evolutionary tradeoff affects eco-evolutionary dynamics in a predator-prey system.

    Science.gov (United States)

    Kasada, Minoru; Yamamichi, Masato; Yoshida, Takehito

    2014-11-11

    Evolution on a time scale similar to ecological dynamics has been increasingly recognized for the last three decades. Selection mediated by ecological interactions can change heritable phenotypic variation (i.e., evolution), and evolution of traits, in turn, can affect ecological interactions. Hence, ecological and evolutionary dynamics can be tightly linked and important to predict future dynamics, but our understanding of eco-evolutionary dynamics is still in its infancy and there is a significant gap between theoretical predictions and empirical tests. Empirical studies have demonstrated that the presence of genetic variation can dramatically change ecological dynamics, whereas theoretical studies predict that eco-evolutionary dynamics depend on the details of the genetic variation, such as the form of a tradeoff among genotypes, which can be more important than the presence or absence of the genetic variation. Using a predator-prey (rotifer-algal) experimental system in laboratory microcosms, we studied how different forms of a tradeoff between prey defense and growth affect eco-evolutionary dynamics. Our experimental results show for the first time to our knowledge that different forms of the tradeoff produce remarkably divergent eco-evolutionary dynamics, including near fixation, near extinction, and coexistence of algal genotypes, with quantitatively different population dynamics. A mathematical model, parameterized from completely independent experiments, explains the observed dynamics. The results suggest that knowing the details of heritable trait variation and covariation within a population is essential for understanding how evolution and ecology will interact and what form of eco-evolutionary dynamics will result.

  7. A snail-eating snake recognizes prey handedness.

    Science.gov (United States)

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-04-05

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal.

  8. Tactile Experience Shapes Prey-Capture Behavior in Etruscan Shrews

    Directory of Open Access Journals (Sweden)

    Michael eBrecht

    2012-06-01

    Full Text Available A crucial role of tactile experience for the maturation of neural response properties in the somatosensory system is well established, but little is known about the role of tactile experience in the development of tactile behaviors. Here we study how tactile experience affects prey capture behavior in Etruscan shrews, Suncus etruscus. Prey capture in adult shrews is a high-speed behavior that relies on precise attacks guided by tactile Gestalt cues. We studied the role of tactile experience by three different approaches. First, we analyzed the hunting skills of young shrews right after weaning. We found that prey capture in young animals is most but not all aspects similar to that of adults. Second we performed whisker trimming for three to four weeks after birth. Such deprivation resulted in a lasting disruption of prey capture even after whisker re-growth: attacks lacked precise targeting and had a lower success rate. Third, we presented adult shrews with an entirely novel prey species, the giant cockroach. The shape of this roach is very different from the shrew’s normal (cricket prey and the thorax – the preferred point of attack in crickets – is protected a heavy cuticle. Initially shrews attacked giant roaches the same way they attack crickets and targeted the thoracic region. With progressive experience, however, shrews adopted a new attack strategy targeting legs and underside of the roaches while avoiding other body parts. Speed and efficiency of attacks improved. These data suggest that tactile experience shapes prey capture behavior.

  9. Genetic models reveal historical patterns of sea lamprey population fluctuations within Lake Champlain

    Directory of Open Access Journals (Sweden)

    Cassidy C. D’Aloia

    2015-10-01

    Full Text Available The origin of sea lamprey (Petromyzon marinus in Lake Champlain has been heavily debated over the past decade. Given the lack of historical documentation, two competing hypotheses have emerged in the literature. First, it has been argued that the relatively recent population size increase and concomitant rise in wounding rates on prey populations are indicative of an invasive population that entered the lake through the Champlain Canal. Second, recent genetic evidence suggests a post-glacial colonization at the end of the Pleistocene, approximately 11,000 years ago. One limitation to resolving the origin of sea lamprey in Lake Champlain is a lack of historical and current measures of population size. In this study, the issue of population size was explicitly addressed using nuclear (nDNA and mitochondrial DNA (mtDNA markers to estimate historical demography with genetic models. Haplotype network analysis, mismatch analysis, and summary statistics based on mtDNA noncoding sequences for NCI (479 bp and NCII (173 bp all indicate a recent population expansion. Coalescent models based on mtDNA and nDNA identified two potential demographic events: a population decline followed by a very recent population expansion. The decline in effective population size may correlate with land-use and fishing pressure changes post-European settlement, while the recent expansion may be associated with the implementation of the salmonid stocking program in the 1970s. These results are most consistent with the hypothesis that sea lamprey are native to Lake Champlain; however, the credibility intervals around parameter estimates demonstrate that there is uncertainty regarding the magnitude and timing of past demographic events.

  10. Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

    Science.gov (United States)

    Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

    2011-11-01

    1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

  11. Individual prey choices of octopuses: Are they generalist or specialist?

    Directory of Open Access Journals (Sweden)

    Jennifer A. MATHER, Tatiana S. LEITE, Allan T. BATISTA

    2012-08-01

    Full Text Available Prey choice is often evaluated at the species or population level. Here, we analyzed the diet of octopuses of different populations with the aim to assess the importance of individual feeding habits as a factor affecting prey choice. Two methods were used, an assessment of the extent to which an individual octopus made choices of species representative of those population (PSi and IS and 25% cutoff values for number of choices and percentage intake of individual on their prey. In one population of Octopus cf vulgaris in Bermuda individuals were generalist by IS=0.77, but most chose many prey of the same species, and were specialists on it by >75% intake. Another population had a wider prey selection, still generalist with PSi=0.66, but two individuals specialized by choices. In Bonaire, there was a wide range of prey species chosen, and the population was specialists by IS= 0.42. Individual choices revealed seven specialists and four generalists. A population of Octopus cyanea in Hawaii all had similar choices of crustaceans, so the population was generalist by IS with 0.74. But by individual choices, three were considered a specialist. A population of Enteroctopus dofleini from Puget Sound had a wide range of preferences, in which seven were also specialists, IS=0.53. By individual choices, thirteen were also specialists. Given the octopus specialty of learning during foraging, we hypothesize that both localized prey availability and individual personality differences could influence the exploration for prey and this translates into different prey choices across individuals and populations showed in this study [Current Zoology 58 (4: 597-603, 2012].

  12. Predator cannibalism can intensify negative impacts on heterospecific prey.

    Science.gov (United States)

    Takatsu, Kunio; Kishida, Osamu

    2015-07-01

    Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing

  13. Temperature and prey capture: opposite relationships in two predator taxa

    DEFF Research Database (Denmark)

    Kruse, Peter Dalgas; Toft, Søren; Sunderland, Keith

    2008-01-01

    to catch swiftly moving prey. 2. The first experiment examined the spontaneous locomotor activity of the predators and of fruit flies at different temperatures (5, 10, 15, 20, 25, and 30 °C) and light conditions (light, dark). A second experiment examined the effect of temperature and light...... different prey groups within the set of potential prey at different times of the day or at different seasons. The ability of many carabid beetles to forage at low temperatures may have nutritional benefits and increases the diversity of interactions in terrestrial food webs....

  14. A self-organized system of smart preys and predators

    Energy Technology Data Exchange (ETDEWEB)

    Rozenfeld, Alejandro F. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CONICET, Suc. 4, C.C. 16 (1900) La Plata (Argentina); Albano, Ezequiel V. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CONICET, Suc. 4, C.C. 16 (1900) La Plata (Argentina)]. E-mail: ealbano@inifta.unlp.edu.ar

    2004-11-22

    Based on the fact that, a standard prey-predator model (SPPM), exhibits irreversible phase transitions, belonging to the universality class of directed percolation (DP), between prey-predator coexistence and predator extinction [Phys. Lett. A 280 (2001) 45], a self-organized prey-predator model (SOPPM) is formulated and studied by means of extensive Monte Carlo simulations. The SOPPM is achieved defining the parameters of the SPPM as functions of the density of species. It is shown that the SOPPM self-organizes into an active state close the absorbing phase of the SPPM, and consequently their avalanche exponents also belong to the universality class of DP.

  15. Modelling prey consumption and switching by UK grey seals

    DEFF Research Database (Denmark)

    Smout, Sophie; Rindorf, Anna; Hammond, Philip S.

    2014-01-01

    Grey seals (Halichoerus grypus) are adaptable generalist predatorswhose diet includes commercial fish species such as cod. Consumption by the seals may reduce the size of some fish stocks or have an adverse effect on stock recovery programmes, especially because predation may trap sparse prey...... populations in a “predator pit”. To assess the likely impact of such effects, it is important to know how consumption and consequent predation mortality respond to the changing availability of prey.Wepresent a model of grey seal consumption as a function of the availability of multiple prey types [a Multi...

  16. Population issues in economic planning: uses of demography in business.

    Science.gov (United States)

    Graham, R J

    1984-01-01

    Economists use demography in planning and forecasting business needs. As a bank, Westpac uses the information for its own internal business purposes and to assess general economic trends. Externally, the bank is expected by government and the public to have some authoritative views on the state of the economy. To form these views, it is necessary to understand a very wide array of statistical indicators, including demographic statistics. The main population issues of concern are: size, location, and changes in the population of Australia as a whole and by State; labor force (including projections); age profile of Australia and by State. The major source for this information is the Australian Bureau of Statistics. More detailed patterns often emerge, particularly for individual States, from papers prepared by others. This information is used by Westpac in 3 main planning areas and 2 broad assessment areas: planning -- location of bank branches, products/services offered, and marketing of products/services; and assessment -- economic outlook (labor force, housing needs, demand for funds) and specific industries. Recently, Westpac restructured its organization to cater to the changing needs of customers and the changing geographic patterns of population spread. The bank now has 4 major groups: retail financial services for personal and commercial markets; corporate and international; management services; and group planning (includes economic department). To offer products that fit the market, the bank needs to know the characteristics of the population by age, spending patterns, lifestyle preferences, and investment needs. Within Australia, a relatively new service offered by most financial institutions, which is directly related to population issues, is a counseling service for retirees. Westpac has a product called Club 55, which is a package of services designed for persons who have retired or are planning to retire. Another clearly perceived community need is for

  17. Benthic prey fish assessment, Lake Ontario 2013

    Science.gov (United States)

    Weidel, Brian C.; Walsh, Maureen; Connerton, Michael J.

    2014-01-01

    abundance and weight indices increased slightly as compared to 2012. The number index value of 16.6 was 30% of the maximum number observed in 2008 when the number index was 95.2. Round Goby density estimates from the 2013 fall benthic prey fish survey were 33 times greater than fall Slimy Sculpin density, indicating Round Goby are now the dominant Lake Ontario benthic prey fish.

  18. Toxoplasmosis in prey species and consequences for prevalence in feral cats: not all prey species are equal.

    Science.gov (United States)

    Afonso, E; Thulliez, P; Pontier, D; Gilot-Fromont, E

    2007-12-01

    Toxoplasma gondii is largely transmitted to definitive felid hosts through predation. Not all prey species represent identical risks of infection for cats because of differences in prey susceptibility, exposure and/or lifespan. Previously published studies have shown that prevalence in rodent and lagomorph species is positively correlated with body mass. We tested the hypothesis that different prey species have different infection risks by comparing infection dynamics of feral cats at 4 sites in the sub-Antarctic Kerguelen archipelago which differed in prey availability. Cats were trapped from 1994 to 2004 and anti-T. gondii IgG antibodies were detected using the modified agglutination test (> or =1:40). Overall seroprevalence was 51.09%. Antibody prevalence differed between sites, depending on diet and also on sex, after taking into account the effect of age. Males were more often infected than females and the difference between the sexes tended to be more pronounced in the site where more prey species were available. A difference in predation efficiency between male and female cats may explain this result. Overall, our results suggest that the composition of prey items in cat diet influences the risk of T. gondii infection. Prey compositon should therefore be considered important in any understanding of infection dynamics of T. gondii.

  19. Demography-adjusted tests of neutrality based on genome-wide SNP data

    KAUST Repository

    Rafajlović, Marina

    2014-08-01

    Tests of the neutral evolution hypothesis are usually built on the standard model which assumes that mutations are neutral and the population size remains constant over time. However, it is unclear how such tests are affected if the last assumption is dropped. Here, we extend the unifying framework for tests based on the site frequency spectrum, introduced by Achaz and Ferretti, to populations of varying size. Key ingredients are the first two moments of the site frequency spectrum. We show how these moments can be computed analytically if a population has experienced two instantaneous size changes in the past. We apply our method to data from ten human populations gathered in the 1000 genomes project, estimate their demographies and define demography-adjusted versions of Tajima\\'s D, Fay & Wu\\'s H, and Zeng\\'s E. Our results show that demography-adjusted test statistics facilitate the direct comparison between populations and that most of the differences among populations seen in the original unadjusted tests can be explained by their underlying demographies. Upon carrying out whole-genome screens for deviations from neutrality, we identify candidate regions of recent positive selection. We provide track files with values of the adjusted and unadjusted tests for upload to the UCSC genome browser. © 2014 Elsevier Inc.

  20. Demography and population status of polar bears in western Hudson Bay

    Science.gov (United States)

    Lunn, Nicholas J.; Regher, Eric V; Servanty, Sabrina; Converse, Sarah J.; Richardson, Evan S.; Stirling, Ian

    2013-01-01

    We evaluated the demography and population status of the Western Hudson Bay (WH) polar bear subpopulation for the period 1984-2011, using live-recapture data from research studies and management actions, and dead-recovery data from polar bears harvested for subsistence purposes or removed during human-bear conflicts.

  1. Demography of northern flying squirrels informs ecosystem management of western interior forests.

    Science.gov (United States)

    John F. Lehmkuhl; Keith D. Kistler; James S. Begley; John. Boulanger

    2006-01-01

    We studied northern flying squirrel (Glaucomys sabrinus) demography in the eastern Washington Cascade Range to test hypotheses about regional and local abundance patterns and to inform managers of the possible effects of fire and fuels management on flying squirrels. We quantified habitat characteristics and squirrel density, population trends, and...

  2. Bayesian analysis of multi-state data with individual covariates for estimating genetic effects on demography

    Science.gov (United States)

    Converse, Sarah J.; Royle, J. Andrew; Urbanek, Richard P.

    2012-01-01

    Inbreeding depression is frequently a concern of managers interested in restoring endangered species. Decisions to reduce the potential for inbreeding depression by balancing genotypic contributions to reintroduced populations may exact a cost on long-term demographic performance of the population if those decisions result in reduced numbers of animals released and/or restriction of particularly successful genotypes (i.e., heritable traits of particular family lines). As part of an effort to restore a migratory flock of Whooping Cranes (Grus americana) to eastern North America using the offspring of captive breeders, we obtained a unique dataset which includes post-release mark-recapture data, as well as the pedigree of each released individual. We developed a Bayesian formulation of a multi-state model to analyze radio-telemetry, band-resight, and dead recovery data on reintroduced individuals, in order to track survival and breeding state transitions. We used studbook-based individual covariates to examine the comparative evidence for and degree of effects of inbreeding, genotype, and genotype quality on post-release survival of reintroduced individuals. We demonstrate implementation of the Bayesian multi-state model, which allows for the integration of imperfect detection, multiple data types, random effects, and individual- and time-dependent covariates. Our results provide only weak evidence for an effect of the quality of an individual's genotype in captivity on post-release survival as well as for an effect of inbreeding on post-release survival. We plan to integrate our results into a decision-analytic modeling framework that can explicitly examine tradeoffs between the effects of inbreeding and the effects of genotype and demographic stochasticity on population establishment.

  3. Prey selection by a reintroduced lion population in the Greater ...

    African Journals Online (AJOL)

    Prey selection by a reintroduced lion population in the Greater Makalali Conservancy, South Africa. Dave Druce, Heleen Genis, Jonathan Braak, Sophie Greatwood, Audrey Delsink, Ross Kettles, Luke Hunter, Rob Slotow ...

  4. An investigation into the chemical composition of alternative invertebrate prey

    NARCIS (Netherlands)

    Oonincx, D.G.A.B.; Dierenfeld, E.S.

    2012-01-01

    The aim of this study was to determine the chemical composition of eight invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red cockroaches (Blatta lateralis), six-spotted cockroaches (Eublaberus distanti), Madagascar hissing cockroaches

  5. Analyses of stomach contents provide information on prey of ...

    African Journals Online (AJOL)

    spamer

    example. In this paper, information is presented on the cephalopods eaten by four species of shark. Initial studies had ..... Their prey selection supports sighting .... 18(1): 27 – 40. KLIMLEY, A. P. 1993 — Highly directional swimming by scal-.

  6. Interaction between Mesodinium rubrum and its prey: importance of prey concentration, irradiance and pH

    DEFF Research Database (Denmark)

    Moldrup, Morten; Hansen, Per Juel

    2007-01-01

    in mixed cultures of M. rubrum and Teleaulax sp. The functional and numerical response study showed that the threshold concentration of the cryptophyte Teleaulax sp. was 50 cells ml-1 and the maximum growth of M. rubrum was 0.23 and 0.49 d-1 for 20 and 100 µE m2 s-1, respectively. Calculation of ingestion...... to starvation showed that M. rubrum could survive for around 50 d without prey. These results are all discussed with respect to M. rubrum's adaptation to its environment....

  7. The effect of habitat structure on prey mortality depends on predator and prey microhabitat use

    Czech Academy of Sciences Publication Activity Database

    Klečka, Jan; Boukal S., David

    2014-01-01

    Roč. 176, č. 1 (2014), s. 183-191 ISSN 0029-8549 R&D Projects: GA ČR GAP505/10/0096 Grant - others:GA JU(CZ) 145/2010/P; EU Marie Curie European Grant(CZ) PERG04-GA-2008-239543 Institutional support: RVO:60077344 Keywords : predation * predator-prey interactions * habitat complexity Subject RIV: EH - Ecology , Behaviour Impact factor: 3.093, year: 2014 http://link.springer.com/article/10.1007%2Fs00442-014-3007-6

  8. Do phytoseiid mites select the best prey species in terms of reproductive success?

    NARCIS (Netherlands)

    Dicke, M.; Sabelis, M.W.; Jong, de M.; Alers, M.P.T.

    1990-01-01

    Optimal foraging theory predicts that predators prefer those prey species that are most rewarding in terms of reproductive success, which is dependent on prey quality and prey availability. To investigate which selection pressures may have moulded prey preference in an acarine system consisting of

  9. Influence of prey body characteristics and performance on predator selection.

    Science.gov (United States)

    Holmes, Thomas H; McCormick, Mark I

    2009-03-01

    At the time of settlement to the reef environment, coral reef fishes differ in a number of characteristics that may influence their survival during a predatory encounter. This study investigated the selective nature of predation by both a multi-species predator pool, and a single common predator (Pseudochromis fuscus), on the reef fish, Pomacentrus amboinensis. The study focused on the early post-settlement period of P. amboinensis, when mortality, and hence selection, is known to be highest. Correlations between nine different measures of body condition/performance were examined at the time of settlement, in order to elucidate the relationships between different traits. Single-predator (P. fuscus) choice trials were conducted in 57.4-l aquaria with respect to three different prey characteristics [standard length (SL), body weight and burst swimming speed], whilst multi-species trials were conducted on open patch reefs, manipulating prey body weight only. Relationships between the nine measures of condition/performance were generally poor, with the strongest correlations occurring between the morphological measures and within the performance measures. During aquaria trials, P. fuscus was found to be selective with respect to prey SL only, with larger individuals being selected significantly more often. Multi-species predator communities, however, were selective with respect to prey body weight, with heavier individuals being selected significantly more often than their lighter counterparts. Our results suggest that under controlled conditions, body length may be the most important prey characteristic influencing prey survival during predatory encounters with P. fuscus. In such cases, larger prey size may actually be a distinct disadvantage to survival. However, these relationships appear to be more complex under natural conditions, where the expression of prey characteristics, the selectivity fields of a number of different predators, their relative abundance, and

  10. Signaling by decorating webs: luring prey or deterring predators?

    OpenAIRE

    Ren-Chung Cheng; I-Min Tso

    2007-01-01

    Many organisms convey false signals to mislead their prey or predators. Some orb-weaving spiders build conspicuous structures on webs called decorations. Web decorations and spider colorations are both suggested to be important signals involved in interactions between spiders and other organisms. There are several hypotheses about the functions of signaling by decorations, among which prey attraction had received much support, but empirical evidence regarding predator defense is controversial...

  11. Mountain lions prey selectively on prion-infected mule deer

    OpenAIRE

    Krumm, Caroline E.; Conner, Mary M.; Hobbs, N. Thompson; Hunter, Don O.; Miller, Michael W.

    2009-01-01

    The possibility that predators choose prey selectively based on age or condition has been suggested but rarely tested. We examined whether mountain lions (Puma concolor) selectively prey upon mule deer (Odocoileus hemionus) infected with chronic wasting disease, a prion disease. We located kill sites of mountain lions in the northern Front Range of Colorado, USA, and compared disease prevalence among lion-killed adult (?2 years old) deer with prevalence among sympatric deer taken by hunters i...

  12. The Dynamical Analysis of a Prey-Predator Model with a Refuge-Stage Structure Prey Population

    Directory of Open Access Journals (Sweden)

    Raid Kamel Naji

    2016-01-01

    Full Text Available We proposed and analyzed a mathematical model dealing with two species of prey-predator system. It is assumed that the prey is a stage structure population consisting of two compartments known as immature prey and mature prey. It has a refuge capability as a defensive property against the predation. The existence, uniqueness, and boundedness of the solution of the proposed model are discussed. All the feasible equilibrium points are determined. The local and global stability analysis of them are investigated. The occurrence of local bifurcation (such as saddle node, transcritical, and pitchfork near each of the equilibrium points is studied. Finally, numerical simulations are given to support the analytic results.

  13. Population variance in prey, diets and their macronutrient composition in an endangered marine predator, the Franciscana dolphin

    Science.gov (United States)

    Denuncio, Pablo; Paso Viola, Maria N.; Machovsky-Capuska, Gabriel E.; Raubenheimer, David; Blasina, Gabriela; Machado, Rodrigo; Polizzi, Paula; Gerpe, Marcela; Cappozzo, Humberto L.; Rodriguez, Diego H.

    2017-11-01

    Disentangling the intricacies governing dietary breadth in wild predators is important for understanding their role in structuring ecological communities and provides critical information for the management and conservation of ecologically threatened species. Here we combined dietary analysis, nutritional composition analysis of prey, literature data and nutritional geometry (right-angled mixture triangle models -RMT-) to examine the diet of the most threatened small cetacean in the western South Atlantic Ocean, the Franciscana dolphin (Pontoporia blainvillei). We applied a recently developed extension of niche theory based on the RMT to help understand the dietary strategies of this species. Our results showed that across their range the Franciscanas consumed prey with variable protein-to-lipid energy ratios (LMM, p < 0.001). In an intensive study of one area, FMA IV, we found that dolphins sub-populations, which recent genetic evidence suggest should be differentiated into three management units, have diets with different protein energy and water mass compositions, but similar protein-to-lipid energy ratios. Furthermore, dolphins from the three areas mixed different combinations of prey in their diets to achieve the observed macronutrient ratios. These results suggest that the different habitats that each sub-population occupies (estuarine, north marine area and south marine) might be associated with different prey composition niches, but similar realized nutritional niches. Future priorities are to better comprehend possible geographical and long-term seasonal effects on prey consumption and dietary breadth of the different Franciscana populations to identify potential impacts (environmental and human-related), enhance the current management strategies to protect this endangered marine predator.

  14. Do lions Panthera leo actively select prey or do prey preferences simply reflect chance responses via evolutionary adaptations to optimal foraging?

    Directory of Open Access Journals (Sweden)

    Matt W Hayward

    Full Text Available Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows, and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.

  15. Do lions Panthera leo actively select prey or do prey preferences simply reflect chance responses via evolutionary adaptations to optimal foraging?

    Science.gov (United States)

    Hayward, Matt W; Hayward, Gina J; Tambling, Craig J; Kerley, Graham I H

    2011-01-01

    Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions) drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows), and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success.

  16. Population structure and historical demography of Dipteronia dyeriana (Sapindaceae), an extremely narrow palaeoendemic plant from China: implications for conservation in a biodiversity hot spot.

    Science.gov (United States)

    Chen, C; Lu, R S; Zhu, S S; Tamaki, I; Qiu, Y X

    2017-08-01

    Inferring past demography is a central question in evolutionary and conservation biology. It is, however, sometimes challenging to disentangle their roles of contemporary versus historical processes in shaping the current patterns of genetic variation in endangered species. In this study, we used both chloroplast microsatellite (cpSSR) loci and nuclear microsatellite (nSSR) loci to assess the levels of genetic differentiation, genetic effective population size, contemporary/historical levels of gene flow and demographic history for five populations sampled across the range of Dipteronia dyeriana, an endangered palaeoendemism from Southwestern China. We found that D. dyeriana had a mixed pattern of moderate genetic diversity and high inbreeding. Bayesian clustering divided D. dyeriana populations into two nSSR genetic clusters. Coalescent-based approximate Bayesian computation analyses suggest the western and eastern groups of D. dyeriana likely persisted in a long-term refuge in Southern China since the beginning of the last glacial period, whereas increasingly colder and arid climates at the onset of the last glacial maximum might have fostered the fragmentation of D. dyeriana within refugia. Following their divergence, the western group kept relatively stable effective population size, whereas the eastern group had experienced 500-fold population expansion during the Holocene. Although clear loss of genetic diversity by human activities was not suggested, recent habitat fragmentation has led to a reduction of population connectivity and increased genetic differentiation by ongoing genetic drift in isolated populations, possibly owing to decreased population size in recent dozen years. Finally, we discussed the implications of these results on conservation policies.

  17. Disentangling mite predator-prey relationships by multiplex PCR.

    Science.gov (United States)

    Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

    2015-11-01

    Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators. © 2015 John Wiley & Sons Ltd.

  18. Prey handling using whole-body fluid dynamics in batoids.

    Science.gov (United States)

    Wilga, Cheryl D; Maia, Anabela; Nauwelaerts, Sandra; Lauder, George V

    2012-02-01

    Fluid flow generated by body movements is a foraging tactic that has been exploited by many benthic species. In this study, the kinematics and hydrodynamics of prey handling behavior in little skates, Leucoraja erinacea, and round stingrays, Urobatis halleri, are compared using kinematics and particle image velocimetry. Both species use the body to form a tent to constrain the prey with the pectoral fin edges pressed against the substrate. Stingrays then elevate the head, which increases the volume between the body and the substrate to generate suction, while maintaining pectoral fin contact with the substrate. Meanwhile, the tip of the rostrum is curled upwards to create an opening where fluid is drawn under the body, functionally analogous to suction-feeding fishes. Skates also rotate the rostrum upwards although with the open rostral sides and the smaller fin area weaker fluid flow is generated. However, skates also use a rostral strike behavior in which the rostrum is rapidly rotated downwards pushing fluid towards the substrate to potentially stun or uncover prey. Thus, both species use the anterior portion of the body to direct fluid flow to handle prey albeit in different ways, which may be explained by differences in morphology. Rostral stiffness and pectoral fin insertion onto the rostrum differ between skates and rays and this corresponds to behavioral differences in prey handling resulting in distinct fluid flow patterns. The flexible muscular rostrum and greater fin area of stingrays allow more extensive use of suction to handle prey while the stiff cartilaginous rostrum of skates lacking extensive fin insertion is used as a paddle to strike prey as well as to clear away sand cover. Copyright © 2011 Elsevier GmbH. All rights reserved.

  19. Demography and life history characteristics of two honey bee races (Apis mellifera).

    Science.gov (United States)

    Winston, Mark L; Dropkin, Jennifer A; Taylor, Orley R

    1981-03-01

    Intra-colony demography and life history characteristics of neotropical Africanized and temperate European honey bearaces were compared under simulated feral conditions. Major differences in colony demography were found which nevertheless resulted in some similar reproductive characteristics. European colonies were larger than Africanized colonies, had more rapid initral growth rates of worker populations, showed better survivorship of brood and adult workers, and differed in patterns of worker age distribution. However, both races were similar in the brood and adult populations when colonies swarmed, the frequency and timing of swarming, and the number of workers in prime swarms. The factors most important in determining these colony growth and reproductive patterns were likely worker mortality rates, climate, and resource availability.

  20. The Demography of Royal Navy Surgeons: Some Views on the Process of Prosopography

    Directory of Open Access Journals (Sweden)

    Christopher H Myers

    2015-08-01

    Full Text Available This study is a brief social biography and demography of British naval doctors during the nineteenth century, asking why Scottish-educated surgeons were so prominent.  Understanding the demography and changing dynamics of naval surgeons’ labor illuminates the complex relationship among the military, discrimination, and nationalism that shaped this influential labor market. This study reviews how to collect demographic information from multiple types of sources: university archives, matriculation records, digitized medical journals, and student rolls.  It also uses chi-square tests to show the significance of the demographic information collected.  The results show us the entangled relationship between database conceptualization, data collection, and data analysis.  

  1. Biomechanics of predator-prey arms race in lion, zebra, cheetah and impala

    Science.gov (United States)

    Wilson, Alan M.; Hubel, Tatjana Y.; Wilshin, Simon D.; Lowe, John C.; Lorenc, Maja; Dewhirst, Oliver P.; Bartlam-Brooks, Hattie L. A.; Diack, Rebecca; Bennitt, Emily; Golabek, Krystyna A.; Woledge, Roger C.; McNutt, J. Weldon; Curtin, Nancy A.; West, Timothy G.

    2018-02-01

    The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator-prey pairs, lion-zebra and cheetah-impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator-prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate.

  2. The hydrodynamics of predator-prey interactions in zebrafish

    Science.gov (United States)

    McHenry, Matthew; Soto, Alberto; Carrillo, Andres; Byron, Margaret

    2017-11-01

    Hydrodynamics govern the behavior of fishes when they operate as predators or prey. In addition to the role of fluid forces in propulsion, fishes relay on flow stimuli to sense a predatory threat and to localize palatable prey. We have performed a series of experiments on zebrafish (Danio rerio) that aim to resolve the major factors that determine whether prey survive an encounter with a predator. Zebrafish serve as a model system in this pursuit because the adults prey on larvae of the same species and the larvae are often successful in evading the attacks of the adults. We use a combination of theoretical and experimental approaches to resolve the behavioral algorithms and kinematics that determined the outcome of these interactions. In this context, the hydrodynamics of intermediate Reynolds numbers largely determines the range of flow stimuli and the limits to locomotor performance at dictate prey survival. These principles have the potential to apply to a broad diversity of fishes and other aquatic animals. ONR: N00014-15-1-2249.

  3. Sequential assessment of prey through the use of multiple sensory cues by an eavesdropping bat

    Science.gov (United States)

    Page, Rachel A.; Schnelle, Tanja; Kalko, Elisabeth K. V.; Bunge, Thomas; Bernal, Ximena E.

    2012-06-01

    Predators are often confronted with a broad diversity of potential prey. They rely on cues associated with prey quality and palatability to optimize their hunting success and to avoid consuming toxic prey. Here, we investigate a predator's ability to assess prey cues during capture, handling, and consumption when confronted with conflicting information about prey quality. We used advertisement calls of a preferred prey item (the túngara frog) to attract fringe-lipped bats, Trachops cirrhosus, then offered palatable, poisonous, and chemically manipulated anurans as prey. Advertisement calls elicited an attack response, but as bats approached, they used additional sensory cues in a sequential manner to update their information about prey size and palatability. While both palatable and poisonous small anurans were readily captured, large poisonous toads were approached but not contacted suggesting the use of echolocation for assessment of prey size at close range. Once prey was captured, bats used chemical cues to make final, post-capture decisions about whether to consume the prey. Bats dropped small, poisonous toads as well as palatable frogs coated in toad toxins either immediately or shortly after capture. Our study suggests that echolocation and chemical cues obtained at close range supplement information obtained from acoustic cues at long range. Updating information about prey quality minimizes the occurrence of costly errors and may be advantageous in tracking temporal and spatial fluctuations of prey and exploiting novel food sources. These findings emphasize the sequential, complex nature of prey assessment that may allow exploratory and flexible hunting behaviors.

  4. Prey size selection and cannibalistic behaviour of juvenile barramundi Lates calcarifer.

    Science.gov (United States)

    Ribeiro, F F; Qin, J G

    2015-05-01

    This study assessed the cannibalistic behaviour of juvenile barramundi Lates calcarifer and examined the relationship between prey size selection and energy gain of cannibals. Prey handling time and capture success by cannibals were used to estimate the ratio of energy gain to energy cost in prey selection. Cannibals selected smaller prey despite its capability of ingesting larger prey individuals. In behavioural analysis, prey handling time significantly increased with prey size, but it was not significantly affected by cannibal size. Conversely, capture success significantly decreased with the increase of both prey and cannibal sizes. The profitability indices showed that the smaller prey provides the most energy return for cannibals of all size classes. These results indicate that L. calcarifer cannibals select smaller prey for more profitable return. The behavioural analysis, however, indicates that L. calcarifer cannibals attack prey of all size at a similar rate but ingest smaller prey more often, suggesting that prey size selection is passively orientated rather than at the predator's choice. The increase of prey escape ability and morphological constraint contribute to the reduction of intracohort cannibalism as fish grow larger. This study contributes to the understanding of intracohort cannibalism and development of strategies to reduce fish cannibalistic mortalities. © 2015 The Fisheries Society of the British Isles.

  5. Comparative growth and development of spiders reared on live and dead prey.

    Science.gov (United States)

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific.

  6. Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response.

    Science.gov (United States)

    Miller, Jennifer R B; Ament, Judith M; Schmitz, Oswald J

    2014-01-01

    Ecologists have long searched for a framework of a priori species traits to help predict predator-prey interactions in food webs. Empirical evidence has shown that predator hunting mode and predator and prey habitat domain are useful traits for explaining predator-prey interactions. Yet, individual experiments have yet to replicate predator hunting mode, calling into question whether predator impacts can be attributed to hunting mode or merely species identity. We tested the effects of spider predators with sit-and-wait, sit-and-pursue and active hunting modes on grasshopper habitat domain, activity and mortality in a grassland system. We replicated hunting mode by testing two spider predator species of each hunting mode on the same grasshopper prey species. We observed grasshoppers with and without each spider species in behavioural cages and measured their mortality rates, movements and habitat domains. We likewise measured the movements and habitat domains of spiders to characterize hunting modes. We found that predator hunting mode explained grasshopper mortality and spider and grasshopper movement activity and habitat domain size. Sit-and-wait spider predators covered small distances over a narrow domain space and killed fewer grasshoppers than sit-and-pursue and active predators, which ranged farther distances across broader domains and killed more grasshoppers, respectively. Prey adjusted their activity levels and horizontal habitat domains in response to predator presence and hunting mode: sedentary sit-and-wait predators with narrow domains caused grasshoppers to reduce activity in the same-sized domain space; more mobile sit-and-pursue predators with broader domains caused prey to reduce their activity within a contracted horizontal (but not vertical) domain space; and highly mobile active spiders led grasshoppers to increase their activity across the same domain area. All predators impacted prey activity, and sit-and-pursue predators generated strong

  7. Feeding behaviour of the nauplii of the marine calanoid copepod Paracartia grani Sars: Functional response, prey size spectrum, and effects of the presence of alternative prey.

    Directory of Open Access Journals (Sweden)

    Laura K Helenius

    Full Text Available Laboratory feeding experiments were conducted to study the functional response and prey size spectrum of the young naupliar stages of the calanoid copepod Paracartia grani Sars. Experiments were conducted on a range of microalgal prey of varying sizes and motility patterns. Significant feeding was found in all prey of a size range of 4.5-19.8 μm, with Holling type III functional responses observed for most prey types. The highest clearance rates occurred when nauplii fed on the dinoflagellate Heterocapsa sp. and the diatom Thalassiosira weissflogii (respectively, 0.61 and 0.70 mL ind-1 d-1, suggesting an optimal prey:predator ratio of 0.09. Additional experiments were conducted to examine the effects of the presence of alternative prey (either Heterocapsa sp. or Gymnodinium litoralis on the functional response to the haptophyte Isochrysis galbana. In the bialgal mixtures, clearance and ingestion rates of I. galbana along the range of the functional response were significantly reduced as a result of selectivity towards the larger, alternative prey. Paradoxically, relatively large prey trigger a perception response in the nauplii, but most likely such prey cannot be completely ingested and a certain degree of sloppy feeding may occur. Our results are further evidence of the complex prey-specific feeding interactions that are likely to occur in natural assemblages with several available prey types.

  8. Predator and prey perception in copepods due to hydromechanical signals

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Visser, Andre

    1999-01-01

    of the different components of the fluid disturbance. We use this model to argue that prey perception depends on the absolute magnitude of the fluid velocity generated by the moving prey, while predator perception depends on the magnitude of one or several of the components of the fluid velocity gradients...... (deformation rate, vorticity, acceleration) generated by the predator. On the assumption that hydrodynamic disturbances are perceived through the mechanical bending of sensory setae, we estimate the magnitude of the signal strength due to each of the fluid disturbance components. We then derive equations...... for reaction distances as a function of threshold signal strength and the size and velocity of the prey or predator. We provide a conceptual framework for quantifying threshold signal strengths and, hence, perception distances. The model is illustrated by several examples, and we demonstrate, for example, (1...

  9. On multi-team predator-prey models

    International Nuclear Information System (INIS)

    Elettreby, M.F.; Saker, S.H.; Ahmed, E.

    2005-05-01

    Many creatures form teams. This has, at least, two main advantages: the first is the improvement in foraging, since looking for food in a team is more efficient than doing it alone. The second is that living in a team reduces predation risk due to early spotting of predators and that existing in a team gives a higher probability that the predator will attack another member of the team. In this paper models are given where two teams of predators interact with two teams of preys. The teams of each group (predators or preys) help each other. In this paper we propose three different versions of the multi-team predator prey model. We study the equilibrium solutions, the conditions of their local asymptotic stability, persistence and the global stability of the solution of one of the models. Some numerical simulations are done. (author)

  10. Influence of poisoned prey on foraging behavior of ferruginous hawks

    Science.gov (United States)

    Vyas, Nimish B.; Kuncir, Frank; Clinton, Criss C.

    2017-01-01

    We recorded 19 visits by ferruginous hawks (Buteo regalis) over 6 d at two black–tailed prairie dog (Cynomys ludovicianus) subcolonies poisoned with the rodenticide Rozol® Prairie Dog Bait (0.005% chlorophacinone active ingredient) and at an adjacent untreated subcolony. Before Rozol® application ferruginous hawks foraged in the untreated and treated subcolonies but after Rozol® application predation by ferruginous hawks was only observed in the treated subcolonies. We suggest that ferruginous hawks' preference for hunting in the treated subcolonies after Rozol® application was influenced by the availability of easy-to-capture prey, presumably due to Rozol® poisoning. The energetically beneficial behavior of favoring substandard prey may increase raptor encounters with rodenticide exposed animals if prey vulnerability has resulted from poisoning.

  11. Release from prey preservation behavior via prey switch allowed diversification of cuticular hydrocarbon profiles in digger wasps.

    Science.gov (United States)

    Wurdack, Mareike; Polidori, Carlo; Keller, Alexander; Feldhaar, Heike; Schmitt, Thomas

    2017-11-01

    The cuticle of insects is covered by a layer of hydrocarbons (CHC), whose original function is the protection from desiccation and pathogens. However, in most insects CHC profiles are species specific. While this variability among species was largely linked to communication and recognition functions, additional selective forces may shape insect CHC profiles. Here, we show that in Philanthinae digger wasps (Crabronidae) the CHC profile coevolved with a peculiar brood-care strategy. In particular, we found that the behavior to embalm prey stored in the nest with hydrocarbons is adaptive to protect larval food from fungi in those species hunting for Hymenoptera. The prey embalming secretion is identical in composition to the alkene-dominated CHC profile in these species, suggesting that their profile is adaptively conserved for this purpose. In contrast, prey embalming is not required in those species that switched to Coleoptera as prey. Released from this chemical brood-care strategy, Coleoptera-hunting species considerably diversified their CHC profiles. Differential needs to successfully protect prey types used as larval food have thus driven the diversification of CHCs profiles of female Philanthinae wasps. To the best of our knowledge, this is the first evidence of a direct link between selection pressure for food preservation and CHC diversity. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  12. Behavior genetic modeling of human fertility

    DEFF Research Database (Denmark)

    Rodgers, J L; Kohler, H P; Kyvik, K O

    2001-01-01

    Behavior genetic designs and analysis can be used to address issues of central importance to demography. We use this methodology to document genetic influence on human fertility. Our data come from Danish twin pairs born from 1953 to 1959, measured on age at first attempt to get pregnant (First......Try) and number of children (NumCh). Behavior genetic models were fitted using structural equation modeling and DF analysis. A consistent medium-level additive genetic influence was found for NumCh, equal across genders; a stronger genetic influence was identified for FirstTry, greater for females than for males....... A bivariate analysis indicated significant shared genetic variance between NumCh and FirstTry....

  13. Revealing the role of predator interference in a predator-prey system with disease in prey population

    DEFF Research Database (Denmark)

    Chakraborty, Subhendu; Kooi, B.W.; Biswas, B.

    2015-01-01

    Predation on a species subjected to an infectious disease can affect both the infection level and the population dynamics. There is an ongoing debate about the act of managing disease in natural populations through predation. Recent theoretical and empirical evidence shows that predation...... on infected populations can have both positive and negative influences on disease in prey populations. Here, we present a predator-prey system where the prey population is subjected to an infectious disease to explore the impact of predator on disease dynamics. Specifically, we investigate how...... on the strength of interference among predators, predators enhance or control disease outbreaks and population persistence. Moreover, the presence of multistable regimes makes the system very sensitive to perturbations and facilitates a number of regime shifts. Since, the habitat structure and the choice...

  14. Predator-Prey Dynamics in the Mesopelagic: Odontocete Foraging Ecology and Anti-predator Behavior of Prey

    Science.gov (United States)

    Benoit-Bird, K. J.

    2016-02-01

    We explored the behavior of Risso's dolphins foraging in scattering layers off California using an integrated approach comprising echosounders deployed in a deep-diving autonomous underwater vehicle, ship based acoustics, visual observations, direct prey sampling, and animal-borne tags on deep-diving predators. We identified three distinct prey layers: a persistent layer around 425 m, a vertically migrating layer around 300 m, and a layer intermittently present near 50 m, all of which were used by individual tagged animals. Active acoustic measurements demonstrated that Risso's dolphins dove to discrete prey layers throughout the day and night with only slightly higher detection rates at night. Dolphins were detected in all three layers during the day with over half of detections in the middle layer, 20% of detections in the deepest layer, and 10% falling outside the main layers. Dolphins were found less frequently in areas where the shallow, intermittent layer was absent, suggesting that this layer, while containing the smallest prey and the lowest densities of squid, was an important component of their foraging strategy. The deepest layer was targeted equally both during the day and at night. Using acoustic data collected from the AUV, we found layers were made up of distinct, small patches of animals of similar size and taxonomy adjacent to contrasting patches. Squid made up over 70% of the patches in which dolphins were found and more than 95% of those in deep water. Squid targeted by dolphins in deep water were also relatively large, indicating significant benefit from these relatively rare, physically demanding dives. Within these patches, prey formed tighter aggregations when Risso's dolphins were present. Careful integration of a suite of traditional and novel tools is providing insight into the ecology and dynamics of predator and prey in the mesopelagic.

  15. Is the red spotted green frog Hypsiboas punctatus (Anura: Hylidae) selecting its preys? The importance of prey availability.

    Science.gov (United States)

    López, Javier A; Scarabotti, Pablo A; Medrano, María C; Ghirardi, Romina

    2009-09-01

    The study of the feeding ecology of amphibians is an old issue in herpetology. Notwithstanding, the lack of food resources data in many studies of amphibians feeding has lead to partial understanding of frog feeding strategies. In this study we evaluate the trophic selectivity of a red spotted green frog (Hypsiboas punctatus) population from a Middle Paraná River floodplain pond in Argentina, and discuss the importance of prey availability data when interpreting results from diet analysis. We analyzed the gut contents of 47 H. punctatus adults and compared frog's diet with the environmental food resources. Prey availability was estimated by systematically seep-netting the microhabitat where anurans were localized foraging. We identified 33 taxonomic categories from gastrointestinal contents. Numerically, the most important prey categories were dipterans, followed by hemipterans, homopterans and coleopterans. The diet similarity between males and females was high and no statistical differences in diet composition were found. The most abundant food resources in the environment were dipterans, coleopterans, homopterans and collembolans. In order to assess whether frogs were selecting their preys, we calculated Pianka's niche overlap index and Jacobs' electivity index comparing gut contents to prey availability data. Trophic niche overlap was medium but significantly higher than expected by chance. The electivity index indicated that H. punctatus foraged dipterans slightly above their environmental abundance. Among the secondary preys, hemipterans were foraged selectively, homopterans were consumed in the same proportion to their occurrence in the environment, coleopterans were foraged quite under their availability and collembolans were practically ignored by frogs. Without food resources data, H. punctatus could be classified as a specialist feeder, but dipterans also were quite abundant in the environment. Our results show that H. punctatus fit better as a

  16. Bifurcations and feedback control of a stage-structure exploited prey ...

    African Journals Online (AJOL)

    user

    Here, we have considered a stage structure prey-predator model with stage structure for ... N over the prey ,N β is the transition rate from mature predator population 2 ...... Mathematical Bioeconomics: The Optimal Management of Renewable ...

  17. An Objective Approach to Determining the Weight Ranges of Prey Preferred by and Accessible to the Five Large African Carnivores

    OpenAIRE

    Clements, Hayley S.; Tambling, Craig J.; Hayward, Matt W.; Kerley, Graham I. H.

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of kno...

  18. Trait-mediated diversification in nematode predator–prey systems

    NARCIS (Netherlands)

    Mulder, C.; Helder, J.; Vervoort, M.T.W.; Vonk, J.A.

    2011-01-01

    Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding

  19. Does colour polymorphism enhance survival of prey populations?

    Science.gov (United States)

    Wennersten, Lena; Forsman, Anders

    2009-01-01

    That colour polymorphism may protect prey populations from predation is an old but rarely tested hypothesis. We examine whether colour polymorphic populations of prey exposed to avian predators in an ecologically valid visual context were exposed to increased extinction risk compared with monomorphic populations. We made 2976 artificial pastry prey, resembling Lepidoptera larvae, in four different colours and presented them in 124 monomorphic and 124 tetramorphic populations on tree trunks and branches such that they would be exposed to predation by free-living birds, and monitored their ‘survival’. Among monomorphic populations, there was a significant effect of prey coloration on survival, confirming that coloration influenced susceptibility to visually oriented predators. Survival of polymorphic populations was inferior to that of monomorphic green populations, but did not differ significantly from monomorphic brown, yellow or red populations. Differences in survival within polymorphic populations paralleled those seen among monomorphic populations; the red morph most frequently went extinct first and the green morph most frequently survived the longest. Our findings do not support the traditional protective polymorphism hypothesis and are in conflict with those of earlier studies. As a possible explanation to our findings, we offer a competing ‘giveaway cue’ hypothesis: that polymorphic populations may include one morph that attracts the attention of predators and that polymorphic populations therefore may suffer increased predation compared with some monomorphic populations. PMID:19324729

  20. Prey, but not plant, chemical discrimination by the lizard ...

    African Journals Online (AJOL)

    We experimentally studied responses to food chemicals by Gerrhosaurus nigrolineatus, amember of a lizard genus endemic to subsaharan Africa. Gerrhosaur diets vary from insectivorous to omnivorous with a very large plant portion. The omnivorous G. validus responds strongly to chemical cues from prey and food plants.

  1. Echolocating bats cry out loud to detect their prey

    DEFF Research Database (Denmark)

    Surlykke, Annemarie; Kalko, Elisabeth K V

    2008-01-01

    Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has b...

  2. Hydrodynamics of prey capture in sharks : effects of substrate

    NARCIS (Netherlands)

    Nauwelaerts, Sandra; Wilga, Cheryl; Sanford, Christopher; Lauder, George

    2007-01-01

    In suction feeding, a volume of water is drawn into the mouth of a predator. Previous studies of suction feeding in fishes have shown that significant fluid velocities are confined to a region within one mouth width from the mouth. Therefore, the predator must be relatively close to the prey to

  3. Direct identification of predator-prey dynamics in gyrokinetic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Sumire, E-mail: sumire.kobayashi@lpp.polytechnique.fr; Gürcan, Özgür D [Laboratoire de Physique des Plasmas, CNRS, Paris-Sud, Ecole Polytechnique, UMR7648, F-91128 Palaiseau (France); Diamond, Patrick H. [University of California, San Diego, La Jolla, California 92093-0319 (United States)

    2015-09-15

    The interaction between spontaneously formed zonal flows and small-scale turbulence in nonlinear gyrokinetic simulations is explored in a shearless closed field line geometry. It is found that when clear limit cycle oscillations prevail, the observed turbulent dynamics can be quantitatively captured by a simple Lotka-Volterra type predator-prey model. Fitting the time traces of full gyrokinetic simulations by such a reduced model allows extraction of the model coefficients. Scanning physical plasma parameters, such as collisionality and density gradient, it was observed that the effective growth rates of turbulence (i.e., the prey) remain roughly constant, in spite of the higher and varying level of primary mode linear growth rates. The effective growth rate that was extracted corresponds roughly to the zonal-flow-modified primary mode growth rate. It was also observed that the effective damping of zonal flows (i.e., the predator) in the parameter range, where clear predator-prey dynamics is observed, (i.e., near marginal stability) agrees with the collisional damping expected in these simulations. This implies that the Kelvin-Helmholtz-like instability may be negligible in this range. The results imply that when the tertiary instability plays a role, the dynamics becomes more complex than a simple Lotka-Volterra predator prey.

  4. Prey capture success and chick diet of Damara terns Sterna ...

    African Journals Online (AJOL)

    Feeding terns are affected by a variety of environmental conditions. We studied prey capture success of Damara terns Sterna balaenarum in relation to six variables at two breeding colonies in southern Namibia: tidal phase, wind speed, water clarity, cloud cover, water depth and locality. Damara terns dived most ...

  5. Predators are attracted to the olfactory signals of prey.

    Directory of Open Access Journals (Sweden)

    Nelika K Hughes

    2010-09-01

    Full Text Available Predator attraction to prey social signals can force prey to trade-off the social imperatives to communicate against the profound effect of predation on their future fitness. These tradeoffs underlie theories on the design and evolution of conspecific signalling systems and have received much attention in visual and acoustic signalling modes. Yet while most territorial mammals communicate using olfactory signals and olfactory hunting is widespread in predators, evidence for the attraction of predators to prey olfactory signals under field conditions is lacking.To redress this fundamental issue, we examined the attraction of free-roaming predators to discrete patches of scents collected from groups of two and six adult, male house mice, Mus domesticus, which primarily communicate through olfaction. Olfactorily-hunting predators were rapidly attracted to mouse scent signals, visiting mouse scented locations sooner, and in greater number, than control locations. There were no effects of signal concentration on predator attraction to their prey's signals.This implies that communication will be costly if conspecific receivers and eavesdropping predators are simultaneously attracted to a signal. Significantly, our results also suggest that receivers may be at greater risk of predation when communicating than signallers, as receivers must visit risky patches of scent to perform their half of the communication equation, while signallers need not.

  6. Insectivorous birds eavesdrop on the pheromones of their prey.

    Science.gov (United States)

    Saavedra, Irene; Amo, Luisa

    2018-01-01

    Chemical cues play a fundamental role in mate attraction and mate choice. Lepidopteran females, such as the winter moth (Operophtera brumata), emit pheromones to attract males in the reproductive period. However, these chemical cues could also be eavesdropped by predators. To our knowledge, no studies have examined whether birds can detect pheromones of their prey. O. brumata adults are part of the winter diet of some insectivorous tit species, such as the great tit (Parus major) and blue tit (Cyanistes caeruleus). We performed a field experiment aimed to disentangle whether insectivorous birds can exploit the pheromones emitted by their prey for prey location. We placed artificial larvae and a dispenser on branches of Pyrenean oak trees (Quercus pyrenaica). In half of the trees we placed an O. brumata pheromone dispenser and in the other half we placed a control dispenser. We measured the predation rate of birds on artificial larvae. Our results show that more trees had larvae with signs of avian predation when they contained an O. brumata pheromone than when they contained a control dispenser. Furthermore, the proportion of artificial larvae with signs of avian predation was greater in trees that contained the pheromone than in control trees. Our results indicate that insectivorous birds can exploit the pheromones emitted by moth females to attract males, as a method of prey detection. These results highlight the potential use of insectivorous birds in the biological control of insect pests.

  7. Chapter 22: Marbled Murrelet Food Habits and Prey Ecology

    Science.gov (United States)

    Esther E. Burkett

    1995-01-01

    Information on food habits of the Marbled Murrelet (Brachyramphus marmoratus) was compiled from systematic studies and anecdotal reports from Alaska to California. Major differences between the winter and summer diets were apparent, with euphausiids and mysids becoming more dominant during winter and spring. The primary invertebrate prey items were...

  8. Stochastic population oscillations in spatial predator-prey models

    International Nuclear Information System (INIS)

    Taeuber, Uwe C

    2011-01-01

    It is well-established that including spatial structure and stochastic noise in models for predator-prey interactions invalidates the classical deterministic Lotka-Volterra picture of neutral population cycles. In contrast, stochastic models yield long-lived, but ultimately decaying erratic population oscillations, which can be understood through a resonant amplification mechanism for density fluctuations. In Monte Carlo simulations of spatial stochastic predator-prey systems, one observes striking complex spatio-temporal structures. These spreading activity fronts induce persistent correlations between predators and prey. In the presence of local particle density restrictions (finite prey carrying capacity), there exists an extinction threshold for the predator population. The accompanying continuous non-equilibrium phase transition is governed by the directed-percolation universality class. We employ field-theoretic methods based on the Doi-Peliti representation of the master equation for stochastic particle interaction models to (i) map the ensuing action in the vicinity of the absorbing state phase transition to Reggeon field theory, and (ii) to quantitatively address fluctuation-induced renormalizations of the population oscillation frequency, damping, and diffusion coefficients in the species coexistence phase.

  9. Lionfish misidentification circumvents an optimized escape response by prey.

    Science.gov (United States)

    McCormick, Mark I; Allan, Bridie J M

    2016-01-01

    Invasive lionfish represent an unprecedented problem in the Caribbean basin, where they are causing major changes to foodwebs and habitats through their generalized predation on fishes and invertebrates. To ascertain what makes the red lionfish ( Pterois volitans ) such a formidable predator, we examined the reaction of a native damselfish prey, the whitetail damsel ( Pomacentrus chrysurus ), to a repeatable startle stimulus once they had been forewarned of the sight or smell of lionfish. Fast-start responses were compared with prey forewarned of a predatory rockcod ( Cephalopholis microprion ), a corallivorous butterflyfish ( Chaetodon trifasctiatus ) and experimental controls. Forewarning of the sight, smell or a combination of the two cues from a rockcod led to reduced escape latencies and higher response distances, speed and maximal speed compared with controls, suggesting that forewarning primed the prey and enabled a more effective escape response. In contrast, forewarning of lionfish did not affect the fast-start kinematics measured, which were the same as in the control and non-predatory butterflyfish treatments. Lionfish appear to be able to circumvent mechanisms commonly used by prey to identify predators and were misclassified as non-predatory, and this is likely to contribute to their success as predators.

  10. Testing for Camouflage Using Virtual Prey and Human "Predators"

    Science.gov (United States)

    Todd, Peter A.

    2009-01-01

    Camouflage is a prevalent feature of the natural world and as such has a ready appeal to students; however, it is a difficult subject to study using real predators and prey. This paper focuses how one fundamental type of camouflage, disruptive colouration (bold markings that break up the outline of the organism), can be tested using paper…

  11. Perceptual advertisement by the prey of stalking or ambushing predators.

    Science.gov (United States)

    Broom, Mark; Ruxton, Graeme D

    2012-12-21

    There has been previous theoretical explorations of the stability of signals by prey that they have detected a stalking or ambush predator, where such perceptual advertisement dissuades the predator from attacking. Here we use a game theoretical model to extend the theory to consider some empirically-motivated complexities: (i) many perceptual advertisement signals appear to have the potential to vary in intensity, (ii) higher intensity signals are likely to be most costly to produce, and (iii) some high-cost signals (such as staring directly at the predator) can only be utilised if the prey is very confident of the existence of a nearby predator (that is, there are reserved or unfakable signals). We demonstrate that these complexities still allow for stable signalling. However, we do not find solutions where prey use a range of signal intensities to signal different degrees of confidence in the proximity of a predator; with prey simply adopting a binary response of not signalling or always signalling at the same fixed level. However this fixed level will not always be the cheapest possible signal, and we predict that prey that require more certainty about proximity of a predator will use higher-cost signals. The availability of reserved signals does not prohibit the stability of signalling based on lower-cost signals, but we also find circumstances where only the reserved signal is used. We discuss the potential to empirically test our model predictions, and to develop theory further to allow perceptual advertisement to be combined with other signalling functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. The relative influence of prey abundance and co-breeders on the ...

    African Journals Online (AJOL)

    This study investigates if the reproductive performance of polyandrous Pale Chanting-goshawks, Melierax canorus, is governed by the abundance of dominant rodent-prey species or a co-breeding male participating fully in prey being delivered to the female and young. Polyandrous trios in prey-rich habitat, the only habitat ...

  13. Irreversible prey diapause as an optimal strategy of a physiologically extended Lotka-Volterra model

    NARCIS (Netherlands)

    Staňková, K.; Abate, A.; Sabelis, M.W.

    2013-01-01

    We propose an optimal control framework to describe intra-seasonal predator-prey interactions, which are characterized by a continuous-time dynamical model comprising predator and prey density, as well as the energy budget of the prey over the length of a season. The model includes a time-dependent

  14. Prey change behaviour with predation threat, but demographic effects vary with prey density: experiments with grasshoppers and birds.

    Science.gov (United States)

    Belovsky, Gary E; Laws, Angela Nardoni; Slade, Jennifer B

    2011-04-01

    Increasingly, ecologists emphasize that prey frequently change behaviour in the presence of predators and these behavioural changes can reduce prey survival and reproduction as much or more than predation itself. However, the effects of behavioural changes on survival and reproduction may vary with prey density due to intraspecific competition. In field experiments, we varied grasshopper density and threat of avian predation and measured grasshopper behaviour, survival and reproduction. Grasshopper behaviour changed with the threat of predation and these behavioural changes were invariant with grasshopper density. Behavioural changes with the threat of predation decreased per capita reproduction over all grasshopper densities; whereas the behavioural changes increased survival at low grasshopper densities and then decreased survival at high densities. At low grasshopper densities, the total reproductive output of the grasshopper population remained unchanged with predation threat, but declined at higher densities. The effects of behavioural changes with predation threat varied with grasshopper density because of a trade-off between survival and reproduction as intraspecific competition increased with density. Therefore, resource availability may need to be considered when assessing how prey behavioural changes with predation threat affect population and food web dynamics. © 2011 Blackwell Publishing Ltd/CNRS.

  15. Stress and body condition are associated with climate and demography in Asian elephants.

    Science.gov (United States)

    Mumby, Hannah S; Mar, Khyne U; Thitaram, Chatchote; Courtiol, Alexandre; Towiboon, Patcharapa; Min-Oo, Zaw; Htut-Aung, Ye; Brown, Janine L; Lummaa, Virpi

    2015-01-01

    Establishing links between ecological variation, physiological markers of stress and demography is crucial for understanding how and why changes in environmental conditions affect population dynamics, and may also play a key role for conservation efforts of endangered species. However, detailed longitudinal studies of long-lived species are rarely available. We test how two markers of stress and body condition vary through the year and are associated with climatic conditions and large-scale mortality and fertility variation in the world's largest semi-captive population of Asian elephants employed in the timber industry in Myanmar. Glucocorticoid metabolites (used as a proxy for stress levels in 75 elephants) and body weight (used as a proxy for condition in 116 elephants) were monitored monthly across a typical monsoon cycle and compared with birth and death patterns of the entire elephant population over half a century (n = 2350). Our results show seasonal variation in both markers of stress and condition. In addition, this variation is correlated with population-level demographic variables. Weight is inversely correlated with population mortality rates 1 month later, and glucocorticoid metabolites are negatively associated with birth rates. Weight shows a highly positive correlation with rainfall 1 month earlier. Determining the factors associated with demography may be key to species conservation by providing information about the correlates of mortality and fertility patterns. The unsustainability of the studied captive population has meant that wild elephants have been captured and tamed for work. By elucidating the correlates of demography in captive elephants, our results offer management solutions that could reduce the pressure on the wild elephant population in Myanmar.

  16. Regions of homozygosity in the porcine genome: consequence of demography and the recombination landscape.

    Directory of Open Access Journals (Sweden)

    Mirte Bosse

    Full Text Available Inbreeding has long been recognized as a primary cause of fitness reduction in both wild and domesticated populations. Consanguineous matings cause inheritance of haplotypes that are identical by descent (IBD and result in homozygous stretches along the genome of the offspring. Size and position of regions of homozygosity (ROHs are expected to correlate with genomic features such as GC content and recombination rate, but also direction of selection. Thus, ROHs should be non-randomly distributed across the genome. Therefore, demographic history may not fully predict the effects of inbreeding. The porcine genome has a relatively heterogeneous distribution of recombination rate, making Sus scrofa an excellent model to study the influence of both recombination landscape and demography on genomic variation. This study utilizes next-generation sequencing data for the analysis of genomic ROH patterns, using a comparative sliding window approach. We present an in-depth study of genomic variation based on three different parameters: nucleotide diversity outside ROHs, the number of ROHs in the genome, and the average ROH size. We identified an abundance of ROHs in all genomes of multiple pigs from commercial breeds and wild populations from Eurasia. Size and number of ROHs are in agreement with known demography of the populations, with population bottlenecks highly increasing ROH occurrence. Nucleotide diversity outside ROHs is high in populations derived from a large ancient population, regardless of current population size. In addition, we show an unequal genomic ROH distribution, with strong correlations of ROH size and abundance with recombination rate and GC content. Global gene content does not correlate with ROH frequency, but some ROH hotspots do contain positive selected genes in commercial lines and wild populations. This study highlights the importance of the influence of demography and recombination on homozygosity in the genome to understand

  17. Demography management and challenges of alternating shift work; Demographiemanagement und Herausforderungen der Wechselschicht

    Energy Technology Data Exchange (ETDEWEB)

    Franzkowiak, Matthias [Arbeitsmedizin Rheinisches Revier, RWE Power AG, Bergheim (Germany); Schmitz, Michael [Personalcontrolling/-strategie, RWE Power AG, Essen (Germany); Feldhaus, Christian [Arbeitsmedizin/Betriebliches Gesundheitsmanagement, RWE Power AG, Essen (Germany)

    2009-07-01

    RWE Power has launched a comprehensive process to develop strategies for future demography management. A special focus is on the challenges which result from the age structure of the workforce in connection with alternating shift work. A comprehensive catalogue of measures was developed which is currently being implemented. Among other things, it includes programmes for the employees on issues like health and ergonomics or optimisation of existing shift systems. Several follow-up projects are also included. The measures presented in this paper are meant to help in responding proactively to future demographic trends and the resulting challenges. (orig.)

  18. Count data, detection probabilities, and the demography, dynamics, distribution, and decline of amphibians.

    Science.gov (United States)

    Schmidt, Benedikt R

    2003-08-01

    The evidence for amphibian population declines is based on count data that were not adjusted for detection probabilities. Such data are not reliable even when collected using standard methods. The formula C = Np (where C is a count, N the true parameter value, and p is a detection probability) relates count data to demography, population size, or distributions. With unadjusted count data, one assumes a linear relationship between C and N and that p is constant. These assumptions are unlikely to be met in studies of amphibian populations. Amphibian population data should be based on methods that account for detection probabilities.

  19. Mechanical work as a determinant of prey-handling behavior in the tokay gecko (Gekko gecko).

    Science.gov (United States)

    Andrews, C; Bertram, J E

    1997-01-01

    In this study an in vitro analysis of the force and mechanical work required to bite prey items of different size and physical character is combined with an in vivo analysis of prey-handling behavior in the tokay gecko (Gekko gecko). The force required to bite and the work of biting increase with prey size, but the rate of increase is prey specific, with crickets (Acheta domestica) requiring substantially more force and work per bite than larvae (Galleria mellonella and Manduca sexta) for all but the smallest prey. Prey-handling behavior is also prey specific. Geckos exert more bites per feeding event on small crickets than on small insect larvae, but the number of bites increases faster with prey mass for larvae than for crickets. Combination of the in vitro mechanical measurements with the in vivo behavior analysis allows the calculation of total mechanical work per feeding event and indicates that total work increases with prey size but that the difference between prey types is far less than predicted from the differences in structural properties of the prey. This occurs because the number of bites and work per bite relationships tend to cancel the differences in the total work necessary to process each prey type. Thus, when considering the effect of prey size, a 13-fold greater rate of increase in bite force and an 18-fold greater rate of increase of work per bit for crickets over larvae was partially compensated for by a threefold increase in the number of bites used on larvae relative to crickets. These results can be interpreted in two ways. The effect of mechanical work in feeding behavior suggests that the energetics of jaw adductor musculature could play a greater role in governing the feeding behavior of this lizard than has previously been expected. Alternatively, the scaling of work in feeding over a range of prey sizes suggests distinct differences in the geometric features of the prey that determine how they are processed.

  20. Who's for dinner? High-throughput sequencing reveals bat dietary differentiation in a biodiversity hotspot where prey taxonomy is largely undescribed.

    Science.gov (United States)

    Burgar, Joanna M; Murray, Daithi C; Craig, Michael D; Haile, James; Houston, Jayne; Stokes, Vicki; Bunce, Michael

    2014-08-01

    Effective management and conservation of biodiversity requires understanding of predator-prey relationships to ensure the continued existence of both predator and prey populations. Gathering dietary data from predatory species, such as insectivorous bats, often presents logistical challenges, further exacerbated in biodiversity hot spots because prey items are highly speciose, yet their taxonomy is largely undescribed. We used high-throughput sequencing (HTS) and bioinformatic analyses to phylogenetically group DNA sequences into molecular operational taxonomic units (MOTUs) to examine predator-prey dynamics of three sympatric insectivorous bat species in the biodiversity hotspot of south-western Australia. We could only assign between 4% and 20% of MOTUs to known genera or species, depending on the method used, underscoring the importance of examining dietary diversity irrespective of taxonomic knowledge in areas lacking a comprehensive genetic reference database. MOTU analysis confirmed that resource partitioning occurred, with dietary divergence positively related to the ecomorphological divergence of the three bat species. We predicted that bat species' diets would converge during times of high energetic requirements, that is, the maternity season for females and the mating season for males. There was an interactive effect of season on female, but not male, bat species' diets, although small sample sizes may have limited our findings. Contrary to our predictions, females of two ecomorphologically similar species showed dietary convergence during the mating season rather than the maternity season. HTS-based approaches can help elucidate complex predator-prey relationships in highly speciose regions, which should facilitate the conservation of biodiversity in genetically uncharacterized areas, such as biodiversity hotspots. © 2013 John Wiley & Sons Ltd.

  1. The global stability of a delayed predator-prey system with two stage-structure

    International Nuclear Information System (INIS)

    Wang Fengyan; Pang Guoping

    2009-01-01

    Based on the classical delayed stage-structured model and Lotka-Volterra predator-prey model, we introduce and study a delayed predator-prey system, where prey and predator have two stages, an immature stage and a mature stage. The time delays are the time lengths between the immature's birth and maturity of prey and predator species. Results on global asymptotic stability of nonnegative equilibria of the delay system are given, which generalize and suggest that good continuity exists between the predator-prey system and its corresponding stage-structured system.

  2. Sabretoothed carnivores and the killing of large prey.

    Directory of Open Access Journals (Sweden)

    Ki Andersson

    Full Text Available Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ∼10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than "megaherbivores" as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of

  3. Prey preferences of the snow leopard (Panthera uncia: regional diet specificity holds global significance for conservation.

    Directory of Open Access Journals (Sweden)

    Salvador Lyngdoh

    Full Text Available The endangered snow leopard is a large felid that is distributed over 1.83 million km(2 globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica, blue sheep (Pseudois nayaur, Himalayan tahr (Hemitragus jemlahicus, argali (Ovis ammon and marmots (Marmota spp. The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  4. Prey preferences of the snow leopard (Panthera uncia): regional diet specificity holds global significance for conservation.

    Science.gov (United States)

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P; Clements, Hayley; Hayward, Matthew W; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based on 1696 analysed scats from throughout the snow leopard's range. Prey biomass consumed was calculated based on the Ackerman's linear correction factor. We identified four distinct physiographic and snow leopard prey type zones, using cluster analysis that had unique prey assemblages and had key prey characteristics which supported snow leopard occurrence there. Levin's index showed the snow leopard had a specialized dietary niche breadth. The main prey of the snow leopard were Siberian ibex (Capra sibrica), blue sheep (Pseudois nayaur), Himalayan tahr (Hemitragus jemlahicus), argali (Ovis ammon) and marmots (Marmota spp). The significantly preferred prey species of snow leopard weighed 55±5 kg, while the preferred prey weight range of snow leopard was 36-76 kg with a significant preference for Siberian ibex and blue sheep. Our meta-analysis identified critical dietary resources for snow leopards throughout their distribution and illustrates the importance of understanding regional variation in species ecology; particularly prey species that have global implications for conservation.

  5. Morphology of seahorse head hydrodynamically aids in capture of evasive prey.

    Science.gov (United States)

    Gemmell, Brad J; Sheng, Jian; Buskey, Edward J

    2013-01-01

    Syngnathid fish (seahorses, pipefish and sea dragons) are slow swimmers yet capture evasive prey (copepods) using a technique known as the 'pivot' feeding, which involves rapid movement to overcome prey escape capabilities. However, this feeding mode functions only at short range and requires approaching very closely to hydrodynamically sensitive prey without triggering an escape. Here we investigate the role of head morphology on prey capture using holographic and particle image velocimetry (PIV). We show that head morphology functions to create a reduced fluid deformation zone, minimizing hydrodynamic disturbance where feeding strikes occur (above the end of the snout), and permits syngnathid fish to approach highly sensitive copepod prey (Acartia tonsa) undetected. The results explain how these animals can successfully employ short range 'pivot' feeding effectively on evasive prey. The need to approach prey with stealth may have selected for a head shape that produces lower deformation rates than other fish.

  6. Retrospective analysis of attitudes to ageing in the Economist: apocalyptic demography for opinion formers.

    Science.gov (United States)

    Martin, Ruth; Williams, Caroline; O'Neill, Desmond

    2009-12-08

    To investigate the description of older people and ageing in a major weekly newspaper, influential in political and financial circles, to see whether it reflected ageing in a balanced manner, and to what extent it indulged in apocalyptic demography-the portrayal of population ageing as a financial burden rather than a scientific advance. Electronic search of the digital archive of the Economist of articles published between January 1997 and April 2008. Main outcomes measures Categorisation of articles as portraying population ageing as a burden or a benefit or with a balanced view. Of 6306 identified articles, 262 were relevant. Most featured pensions, demography, and politics. Of these 262, 64% portrayed population ageing as a burden and 12% as a benefit; 24% had a balanced view. Most articles therefore showed a predominantly ageist view of older people as a burden on society, often portraying them as frail non-contributors. Recurrent themes included pension and demographic "time bombs" and future unsustainable costs of health care for older people. This negative view of older people might be influential in shaping the attitudes of readers, who include opinion formers in political and economic circles. Gerontologists (including geriatricians) need to engage with influential media, as well as helping to promote a professional development of journalists that is informed and knowledgeable about the negative impact of ageism on the wellbeing of older people.

  7. Late Holocene Lake Level Fluctuations at Laguna Arapa, Peru and Connections to Human Demography

    Science.gov (United States)

    Hillman, A. L.; Abbott, M. B.; Werne, J. P.; Arkush, E.; Thompson, L. G.; Ferland, T.; Holmes, E.; Puhnaty, C.; Woods, A.

    2016-12-01

    The relationship between variations in hydroclimate and human demography on the Peruvian Altiplano has significant implications for understanding how people in the past have adapted to changes in freshwater resources. To investigate these human-environmental interactions, this project presents a 2,000 year sediment record from Laguna Arapa, a large lake that is Titicaca. Using sedimentology and stratigraphy as well as a suite of organic geochemical proxies including fecal 5β-stanols and leaf waxes (long chain n-alkanoic acids), we aim to tie together proxies of human population with indicators of regional hydroclimate. Preliminary results of sedimentology and stratigraphy show notable transitions from sand to silt to clay, suggesting rising lake level sequences at 500 and 700 AD. The last 1,300 years of sediment are characterized by alternating layers of organic rich material with abundant charcoal and black inorganic clay, suggesting intermittent periods of aridity and/or anthropogenic fire-setting. These layers are particularly frequent during the Medieval Climate Anomaly, which was characterized by dry and warm conditions. These results agree well with other records of hydroclimate from regional lakes as well as accumulation rate and temperature from the Quelccaya ice cap. Organic geochemical work is currently in progress and shows promise for linking together proxies of human demography with hydroclimate to understand the relationship between human settlement and climate change.

  8. Women, Demography, and Politics: How Lower Fertility Rates Lead to Democracy.

    Science.gov (United States)

    Sommer, Udi

    2018-04-01

    Where connections between demography and politics are examined in the literature, it is largely in the context of the effects of male aspects of demography on phenomena such as political violence. This project aims to place the study of demographic variables' influence on politics, particularly on democracy, squarely within the scope of political and social sciences, and to focus on the effects of woman-related demographics-namely, fertility rate. I test the hypothesis that demographic variables-female-related predictors, in particular-have an independent effect on political structure. Comparing countries over time, this study finds a growth in democracy when fertility rates decline. In the theoretical framework developed, it is family structure as well as the economic and political status of women that account for this change at the macro and micro levels. Findings based on data for more than 140 countries over three decades are robust when controlling not only for alternative effects but also for reverse causality and data limitations.

  9. Evolutionary demography and the population history of the European early Neolithic.

    Science.gov (United States)

    Shennan, Stephen

    2009-04-01

    In this paper I propose that evolutionary demography and associated theory from human behavioral ecology provide a strong basis for explaining the available evidence for the patterns observed in the first agricultural settlement of Europe in the 7th-5th millennium cal. BC, linking together a variety of what have previously been disconnected observations and casting doubt on some long-standing existing models. An outline of relevant aspects of life history theory, which provides the foundation for understanding demography, is followed by a review of large-scale demographic patterns in the early Neolithic, which point to rapid population increase and a process of demic diffusion. More localized socioeconomic and demographic patterns suggesting rapid expansion to local carrying capacities and an associated growth of inequality in the earliest farming communities of central Europe (the Linear Pottery Culture, or LBK) are then outlined and shown to correspond to predictions of spatial population ecology and reproductive skew theory. Existing models of why it took so long for farming to spread to northern and northwest Europe, which explain the spread in terms of the gradual disruption of hunter-gatherer ways of life, are then questioned in light of evidence for population collapse at the end of the LBK. Finally, some broader implications of the study are presented, including the suggestion that the pattern of an initial agricultural boom followed by a bust may be relevant in other parts of the world.

  10. Reproductive demography of a temperate protogynous and herbivorous fish, Odax pullus (Labridae, Odacini)

    KAUST Repository

    Laman Trip, Elizabeth; Raubenheimer, David; Clements, Kendall D.; Choat, John Howard

    2011-01-01

    A common view is that, in marine fishes, herbivory and sex change are subject to physiological constraints at high latitudes, which are likely to affect growth rates and reproductive outputs. The present study examines the reproductive demography of Odax pullus, an herbivorous and protogynous species of temperate New Zealand. We establish an otolith-based methodology for age estimation and investigate sex-specific growth, longevity and age-based reproductive events. Individuals achieved a maximum age of 11 years, reached 85% of adult body size (455mm FL) within the first 3.5 years of life, were sexually mature by the age of 1.11.5 years and changed sex at 2.83.5 years, indicating fast simultaneous somatic and reproductive growth. There was no significant difference in growth or body size between the sexes. Ovary weight of spawning females increased significantly with size and age, suggesting the presence of size- and age-fecundity skews underlying the absence of sex change in larger and older females. Testes of reproductively active males comprised less than 1% of bodyweight, suggesting pair-spawning and little sperm competition. The present study provides metrics to support comparisons of the demography of this temperate protogynous and herbivorous labrid across spatial or temporal strata. © CSIRO 2011.

  11. Reproductive demography of a temperate protogynous and herbivorous fish, Odax pullus (Labridae, Odacini)

    KAUST Repository

    Laman Trip, Elizabeth

    2011-03-07

    A common view is that, in marine fishes, herbivory and sex change are subject to physiological constraints at high latitudes, which are likely to affect growth rates and reproductive outputs. The present study examines the reproductive demography of Odax pullus, an herbivorous and protogynous species of temperate New Zealand. We establish an otolith-based methodology for age estimation and investigate sex-specific growth, longevity and age-based reproductive events. Individuals achieved a maximum age of 11 years, reached 85% of adult body size (455mm FL) within the first 3.5 years of life, were sexually mature by the age of 1.11.5 years and changed sex at 2.83.5 years, indicating fast simultaneous somatic and reproductive growth. There was no significant difference in growth or body size between the sexes. Ovary weight of spawning females increased significantly with size and age, suggesting the presence of size- and age-fecundity skews underlying the absence of sex change in larger and older females. Testes of reproductively active males comprised less than 1% of bodyweight, suggesting pair-spawning and little sperm competition. The present study provides metrics to support comparisons of the demography of this temperate protogynous and herbivorous labrid across spatial or temporal strata. © CSIRO 2011.

  12. Small prey species' behaviour and welfare: implications for veterinary professionals.

    Science.gov (United States)

    McBride, E Anne

    2017-08-01

    People have obligations to ensure the welfare of animals under their care. Offences under the UK Animal Welfare Act are acts, or failures of action, causing unnecessary suffering. Veterinary professionals need to be able to provide current, scientifically based prophylactic advice, and respect the limits of their expertise. The ethical concept of a life worth living and the Five Freedoms are core to welfare. Behaviour is a central component, both influencing and influenced by physical health. Owners frequently misunderstand the behaviour of small prey mammals and how to meet their needs. This review provides insight into the physical-social (external) and the cognitive-emotional (internal) environments of small prey mammals, contextualised within an evolutionary perspective. This is extrapolated to captivity and practical suggestions given for meeting behavioural freedoms and enhancing client understanding and enjoyment of their animals, thereby improving welfare. © 2017 British Small Animal Veterinary Association.

  13. Environmental versus demographic variability in stochastic predator–prey models

    International Nuclear Information System (INIS)

    Dobramysl, U; Täuber, U C

    2013-01-01

    In contrast to the neutral population cycles of the deterministic mean-field Lotka–Volterra rate equations, including spatial structure and stochastic noise in models for predator–prey interactions yields complex spatio-temporal structures associated with long-lived erratic population oscillations. Environmental variability in the form of quenched spatial randomness in the predation rates results in more localized activity patches. Our previous study showed that population fluctuations in rare favorable regions in turn cause a remarkable increase in the asymptotic densities of both predators and prey. Very intriguing features are found when variable interaction rates are affixed to individual particles rather than lattice sites. Stochastic dynamics with demographic variability in conjunction with inheritable predation efficiencies generate non-trivial time evolution for the predation rate distributions, yet with overall essentially neutral optimization. (paper)

  14. Bifurcation Behavior Analysis in a Predator-Prey Model

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2016-01-01

    Full Text Available A predator-prey model is studied mathematically and numerically. The aim is to explore how some key factors influence dynamic evolutionary mechanism of steady conversion and bifurcation behavior in predator-prey model. The theoretical works have been pursuing the investigation of the existence and stability of the equilibria, as well as the occurrence of bifurcation behaviors (transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation, which can deduce a standard parameter controlled relationship and in turn provide a theoretical basis for the numerical simulation. Numerical analysis ensures reliability of the theoretical results and illustrates that three stable equilibria will arise simultaneously in the model. It testifies the existence of Bogdanov-Takens bifurcation, too. It should also be stressed that the dynamic evolutionary mechanism of steady conversion and bifurcation behavior mainly depend on a specific key parameter. In a word, all these results are expected to be of use in the study of the dynamic complexity of ecosystems.

  15. Vertebrate predator-prey interactions in a seasonal environment

    DEFF Research Database (Denmark)

    Schmidt, Niels Martin; Berg, Thomas B; Forchhammer, Mads

    2008-01-01

    erminea predation and stabilising predation from the generalist predators, in Zackenbergdalen mainly the arctic fox Alopex lagopus. In Zackenbergdalen, however, the coupling between the specialist stoat and the lemming population is relatively weak. During summer, the predation pressure is high......The High Arctic, with its low number of species, is characterised by a relatively simple ecosystem, and the vertebrate predator-prey interactions in the valley Zackenbergdalen in Northeast Greenland are centred around the collared lemming Dicrostonyx groenlandicus and its multiple predators...

  16. The Neuronal Control of Flying Prey Interception in Dragonflies

    Science.gov (United States)

    2014-08-19

    Gonzalez-Bellido’s fluorescent dye ( Lucifer -yellow) injections illuminated for the first time the anatomy of the output regions of the TSDNs...out in Cape Cod (MA) to test the effect of bead size(C), and in the Olberg Laboratory (Union College, NY) to test the effect of bead speed by...AFRL-OSR-VA-TR-2014-0193 THE NEURONAL CONTROL OF FLYING PREY INTERCEPTION IN DRAGONFLIES Robert Olberg TRUSTEES OF UNION COLLEGE IN THE TOWN OF

  17. Prey selection of Tawny owls (Strix aluco) on Yellow necked mouse and Bank Vole

    DEFF Research Database (Denmark)

    Forsom, H. M.; Sunde, P.; Overskaug, K.

    As predators owls may have a strong impact on mortality of their favourite prey, and may therefore act as important selective agents on their prey species. Little is known, however, about whether owls choose prey randomly or if some prey items suffer a higher risk of predation due to certain life...

  18. Mountain lions prey selectively on prion-infected mule deer

    Science.gov (United States)

    Krumm, Caroline E.; Conner, Mary M.; Hobbs, N. Thompson; Hunter, Don O.; Miller, Michael W.

    2010-01-01

    The possibility that predators choose prey selectively based on age or condition has been suggested but rarely tested. We examined whether mountain lions (Puma concolor) selectively prey upon mule deer (Odocoileus hemionus) infected with chronic wasting disease, a prion disease. We located kill sites of mountain lions in the northern Front Range of Colorado, USA, and compared disease prevalence among lion-killed adult (≥2 years old) deer with prevalence among sympatric deer taken by hunters in the vicinity of kill sites. Hunter-killed female deer were less likely to be infected than males (odds ratios (OR) = 0.2, 95% confidence intervals (CI) = 0.1–0.6; p = 0.015). However, both female (OR = 8.5, 95% CI = 2.3–30.9) and male deer (OR = 3.2, 95% CI = 1–10) killed by a mountain lion were more likely to be infected than same-sex deer killed in the vicinity by a hunter (p < 0.001), suggesting that mountain lions in this area actively selected prion-infected individuals when targeting adult mule deer as prey items. PMID:19864271

  19. Predator size and the suitability of a common prey.

    Science.gov (United States)

    Erickson, Kristin S; Morse, D H

    1997-02-01

     Although a predator's mass should influence the suitability of its prey, this subject has received little direct attention. We studied the capture and processing of an abundant syrphid fly Toxomerus marginatus (c. 4 mg) by 0.6- to 40-mg juvenile crab spiders Misumena vatia (Thomisidae) to determine how profitability, relative profitability (profitability/predator mass), overall gain in mass, and relative gain in mass differed with predator mass, and whether foraging changed concurrently. In multi-prey experiments, the smallest successful spiders (0.6-3.0 mg) extracted less mass from flies, and did so more slowly, than large spiders. This gain was proportionately similar to that of 10- to 40-mg spiders with access to many Toxomerus. However, many small spiders failed to capture flies. When we gave spiders only a single Toxomerus, the smallest ones again extracted mass more slowly than the large ones and increased in mass less than the large ones, but increased in mass proportionately more than large ones. Relative gain in mass from a single prey decreased with increasing spider mass. Spiders larger than 10 mg all extracted similar amounts of mass from a single Toxomerus at similar rates, but varied in time spent between captures. Thus, Toxomerus changes with spider mass from a large, hard-to-capture bonanza to a small, easy-to-capture item of low per capita value. However, Toxomerus is common enough that large spiders can capture it en masse, thereby compensating for its decline in per capita value.

  20. Brominated flame retardants in birds of prey from Flanders, Belgium

    Energy Technology Data Exchange (ETDEWEB)

    Voorspoels, S.; Covaci, A.; Schepens, P. [Antwerp Univ., Wilrijk (Belgium). Toxicological Centre

    2004-09-15

    Since their introduction on the market, environmental levels of polybrominated diphenyl ethers (PBDEs) are continuously increasing. This is caused by spillage and emission during production and use, but also by improper disposal at the end-of-life of the products in which they are used. These chemicals are highly persistent and lipophilic which results in bioaccumulation in fatty tissues of biota and biomagnification throughout the food chain. Because PBDEs have a high toxicological potential, this biomagnification can have serious health consequences for top-predators, such as birds of prey. Data about PBDE concentrations in terrestrial biota, especially in birds of prey, is scarce. A rapid increase of PBDE concentrations has been seen in pooled guillemot (Uria algae) eggs from the Baltic proper7 during the late 1970's and early 1980's, followed by a decrease during the 1990's8. In herring gull eggs from the Great Lakes, the PBDE concentrations increased exponentially from 1981 to 2000. Most of the studies look at concentrations in eggs, while less is known about tissue levels and distribution of these pollutants in birds of prey.

  1. Jewelled spiders manipulate colour-lure geometry to deceive prey.

    Science.gov (United States)

    White, Thomas E

    2017-03-01

    Selection is expected to favour the evolution of efficacy in visual communication. This extends to deceptive systems, and predicts functional links between the structure of visual signals and their behavioural presentation. Work to date has primarily focused on colour, however, thereby understating the multicomponent nature of visual signals. Here I examined the relationship between signal structure, presentation behaviour, and efficacy in the context of colour-based prey luring. I used the polymorphic orb-web spider Gasteracantha fornicata , whose yellow- or white-and-black striped dorsal colours have been broadly implicated in prey attraction. In a manipulative assay, I found that spiders actively control the orientation of their conspicuous banded signals in the web, with a distinct preference for near-diagonal bearings. Further field-based study identified a predictive relationship between pattern orientation and prey interception rates, with a local maximum at the spiders' preferred orientation. There were no morph-specific effects on capture success, either singularly or via an interaction with pattern orientation. These results reveal a dynamic element in a traditionally 'static' signalling context, and imply differential functions for chromatic and geometric signal components across visual contexts. More broadly, they underscore how multicomponent signal designs and display behaviours may coevolve to enhance efficacy in visual deception. © 2017 The Author(s).

  2. Find the weakest link. A comparison between demographic, genetic and demo-genetic metapopulation extinction times

    Directory of Open Access Journals (Sweden)

    Robert Alexandre

    2011-09-01

    Full Text Available Abstract Background While the ultimate causes of most species extinctions are environmental, environmental constraints have various secondary consequences on evolutionary and ecological processes. The roles of demographic, genetic mechanisms and their interactions in limiting the viabilities of species or populations have stirred much debate and remain difficult to evaluate in the absence of demography-genetics conceptual and technical framework. Here, I computed projected times to metapopulation extinction using (1 a model focusing on the effects of species properties, habitat quality, quantity and temporal variability on the time to demographic extinction; (2 a genetic model focusing on the dynamics of the drift and inbreeding loads under the same species and habitat constraints; (3 a demo-genetic model accounting for demographic-genetic processes and feedbacks. Results Results indicate that a given population may have a high demographic, but low genetic viability or vice versa; and whether genetic or demographic aspects will be the most limiting to overall viability depends on the constraints faced by the species (e.g., reduction of habitat quantity or quality. As a consequence, depending on metapopulation or species characteristics, incorporating genetic considerations to demographically-based viability assessments may either moderately or severely reduce the persistence time. On the other hand, purely genetically-based estimates of species viability may either underestimate (by neglecting demo-genetic interactions or overestimate (by neglecting the demographic resilience true viability. Conclusion Unbiased assessments of the viabilities of species may only be obtained by identifying and considering the most limiting processes (i.e., demography or genetics, or, preferentially, by integrating them.

  3. Noise-induced extinction for a ratio-dependent predator-prey model with strong Allee effect in prey

    Science.gov (United States)

    Mandal, Partha Sarathi

    2018-04-01

    In this paper, we study a stochastically forced ratio-dependent predator-prey model with strong Allee effect in prey population. In the deterministic case, we show that the model exhibits the stable interior equilibrium point or limit cycle corresponding to the co-existence of both species. We investigate a probabilistic mechanism of the noise-induced extinction in a zone of stable interior equilibrium point. Computational methods based on the stochastic sensitivity function technique are applied for the analysis of the dispersion of random states near stable interior equilibrium point. This method allows to construct a confidence domain and estimate the threshold value of the noise intensity for a transition from the coexistence to the extinction.

  4. Red trap colour of the carnivorous plant Drosera rotundifolia does not serve a prey attraction or camouflage function.

    Science.gov (United States)

    Foot, G; Rice, S P; Millett, J

    2014-01-01

    The traps of many carnivorous plants are red in colour. This has been widely hypothesized to serve a prey attraction function; colour has also been hypothesized to function as camouflage, preventing prey avoidance. We tested these two hypotheses in situ for the carnivorous plant Drosera rotundifolia. We conducted three separate studies: (i) prey attraction to artificial traps to isolate the influence of colour; (ii) prey attraction to artificial traps on artificial backgrounds to control the degree of contrast and (iii) observation of prey capture by D. rotundifolia to determine the effects of colour on prey capture. Prey were not attracted to green traps and were deterred from red traps. There was no evidence that camouflaged traps caught more prey. For D. rotundifolia, there was a relationship between trap colour and prey capture. However, trap colour may be confounded with other leaf traits. Thus, we conclude that for D. rotundifolia, red trap colour does not serve a prey attraction or camouflage function.

  5. Echolocating bats cry out loud to detect their prey.

    Directory of Open Access Journals (Sweden)

    Annemarie Surlykke

    Full Text Available Echolocating bats have successfully exploited a broad range of habitats and prey. Much research has demonstrated how time-frequency structure of echolocation calls of different species is adapted to acoustic constraints of habitats and foraging behaviors. However, the intensity of bat calls has been largely neglected although intensity is a key factor determining echolocation range and interactions with other bats and prey. Differences in detection range, in turn, are thought to constitute a mechanism promoting resource partitioning among bats, which might be particularly important for the species-rich bat assemblages in the tropics. Here we present data on emitted intensities for 11 species from 5 families of insectivorous bats from Panamá hunting in open or background cluttered space or over water. We recorded all bats in their natural habitat in the field using a multi-microphone array coupled with photographic methods to assess the bats' position in space to estimate emitted call intensities. All species emitted intense search signals. Output intensity was reduced when closing in on background by 4-7 dB per halving of distance. Source levels of open space and edge space foragers (Emballonuridae, Mormoopidae, Molossidae, and Vespertilionidae ranged between 122-134 dB SPL. The two Noctilionidae species hunting over water emitted the loudest signals recorded so far for any bat with average source levels of ca. 137 dB SPL and maximum levels above 140 dB SPL. In spite of this ten-fold variation in emitted intensity, estimates indicated, surprisingly, that detection distances for prey varied far less; bats emitting the highest intensities also emitted the highest frequencies, which are severely attenuated in air. Thus, our results suggest that bats within a local assemblage compensate for frequency dependent attenuation by adjusting the emitted intensity to achieve comparable detection distances for prey across species. We conclude that for bats

  6. Occurrence of enteropathogenic bacteria in birds of prey in Italy.

    Science.gov (United States)

    Gargiulo, A; Fioretti, A; Russo, T P; Varriale, L; Rampa, L; Paone, S; De Luca Bossa, L M; Raia, P; Dipineto, L

    2018-03-01

    The importance of wild birds as potential vectors of disease has received recent renewed empirical interest, especially regarding human health although information regarding the enteropathogenic bacteria in birds of prey continue to be scant. This study was performed with the aim to evaluate the occurrence of enteropathogenic bacteria (i.e. Campylobacter spp. Escherichia coli, Salmonella spp.) in birds of prey carcasses in Southern Italy. The results of the present study showed a prevalence of 33·1% (49/148) for Campylobacter spp. where all positive isolates (49/49) were identified as Campylobacter jejuni, and among these positive 12/49 were also identified as Campylobacter coli. Thus, 12/49 birds of prey showed mixed infections for both Campylobacter species. Differences in Campylobacter spp. prevalence between diurnal and nocturnal birds were statistically significant (P = 0·016). Escherichia coli showed a prevalence of 6·8% (10/148) and were serogrouped as O26 (n = 3), O55 (n = 2), O145 (n = 5). Salmonella spp. showed a prevalence of 6·8% (10/148) and were serotyped as S. Napoli (n = 4), Salmonella salamae (n = 3) and S. Typhimurium (n = 3). Although wildlife disease outbreaks have often been underreported in the broader context of global epidemiology, results of the present study suggest that birds of prey may serve as a reservoir of pathogens for livestock and human health, acting at the animal-human-ecosystem interface. This study confirms the role of birds of prey as a reservoir of enteropathogenic bacteria (i.e. Campylobacter spp., Escherichia coli, Salmonella spp.). Wild birds can contaminate environment with their faeces and play a crucial role in the transmission of pathogens to poultry and livestock farms and aquifers supplying water to humans. Furthermore, wild birds could disseminate pathogens within rescue and rehabilitation centres where they are admitted. © 2017 The Society for Applied Microbiology.

  7. Weather and Prey Predict Mammals' Visitation to Water.

    Directory of Open Access Journals (Sweden)

    Grant Harris

    Full Text Available Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water provisioning requires identifying why and when animals visit water. Employing this information, by matching water provisioning with use by target species, could assist wildlife management objectives while mitigating unintended consequences of year-round watering regimes. Therefore, we examined if weather variables (maximum temperature, relative humidity [RH], vapor pressure deficit [VPD], long and short-term precipitation and predator-prey relationships (i.e., prey presence predicted water visitation by 9 mammals. We modeled visitation as recorded by trail cameras at Sevilleta National Wildlife Refuge, New Mexico, USA (June 2009 to September 2014 using generalized linear modeling. For 3 native ungulates, elk (Cervus Canadensis, mule deer (Odocoileus hemionus, and pronghorn (Antilocapra americana, less long-term precipitation and higher maximum temperatures increased visitation, including RH for mule deer. Less long-term precipitation and higher VPD increased oryx (Oryx gazella and desert cottontail rabbits (Sylvilagus audubonii visitation. Long-term precipitation, with RH or VPD, predicted visitation for black-tailed jackrabbits (Lepus californicus. Standardized model coefficients demonstrated that the amount of long-term precipitation influenced herbivore visitation most. Weather (especially maximum temperature and prey (cottontails and jackrabbits predicted bobcat (Lynx rufus visitation. Mule deer visitation had the largest influence on coyote (Canis latrans visitation. Puma (Puma concolor visitation was solely predicted by prey visitation (elk, mule deer, oryx. Most ungulate visitation peaked during

  8. Weather and Prey Predict Mammals’ Visitation to Water

    Science.gov (United States)

    Harris, Grant; Sanderson, James G.; Erz, Jon; Lehnen, Sarah E.; Butler, Matthew J.

    2015-01-01

    Throughout many arid lands of Africa, Australia and the United States, wildlife agencies provide water year-round for increasing game populations and enhancing biodiversity, despite concerns that water provisioning may favor species more dependent on water, increase predation, and reduce biodiversity. In part, understanding the effects of water provisioning requires identifying why and when animals visit water. Employing this information, by matching water provisioning with use by target species, could assist wildlife management objectives while mitigating unintended consequences of year-round watering regimes. Therefore, we examined if weather variables (maximum temperature, relative humidity [RH], vapor pressure deficit [VPD], long and short-term precipitation) and predator-prey relationships (i.e., prey presence) predicted water visitation by 9 mammals. We modeled visitation as recorded by trail cameras at Sevilleta National Wildlife Refuge, New Mexico, USA (June 2009 to September 2014) using generalized linear modeling. For 3 native ungulates, elk (Cervus Canadensis), mule deer (Odocoileus hemionus), and pronghorn (Antilocapra americana), less long-term precipitation and higher maximum temperatures increased visitation, including RH for mule deer. Less long-term precipitation and higher VPD increased oryx (Oryx gazella) and desert cottontail rabbits (Sylvilagus audubonii) visitation. Long-term precipitation, with RH or VPD, predicted visitation for black-tailed jackrabbits (Lepus californicus). Standardized model coefficients demonstrated that the amount of long-term precipitation influenced herbivore visitation most. Weather (especially maximum temperature) and prey (cottontails and jackrabbits) predicted bobcat (Lynx rufus) visitation. Mule deer visitation had the largest influence on coyote (Canis latrans) visitation. Puma (Puma concolor) visitation was solely predicted by prey visitation (elk, mule deer, oryx). Most ungulate visitation peaked during May and

  9. Bottom trawl assessment of Lake Ontario prey fishes

    Science.gov (United States)

    Weidel, Brian C.; Connerton, Michael J.; Holden, Jeremy

    2018-01-01

    Managing Lake Ontario fisheries in an ecosystem-context requires prey fish community and population data. Since 1978, multiple annual bottom trawl surveys have quantified prey fish dynamics to inform management relative to published Fish Community Objectives. In 2017, two whole-lake surveys collected 341 bottom trawls (spring: 204, fall: 137), at depths from 8-225m, and captured 751,350 fish from 29 species. Alewife were 90% of the total fish catch while Deepwater Sculpin, Round Goby, and Rainbow Smelt comprised the majority of the remaining total catch (3.8, 3.1, and 1.1% respectively). The adult Alewife abundance index for US waters increased in 2017 relative to 2016, however the index for Canadian waters declined. Adult Alewife condition, assessed by the predicted weight of a 165 mm fish (6.5 inches), declined in 2017 from record high values observed in spring 2016. Spring 2017 Alewife condition was slightly less than the 10-year average, but the fall value was well below the 10-year average, likely due to increased Age-1 Alewife abundance. The Age-1 Alewife abundance index was the highest observed in 40 years, and 8-times higher than the previous year. The Age-1 index estimates Alewife reproductive success the preceding year. The warm summer and winter of 2016 likely contributed to the large year class. In contrast the relatively cool 2017 spring and cold winter may result in a lower than average 2017 year class. Abundance indices for Rainbow Smelt, Cisco, and Emerald Shiner either declined or remained at low levels in 2017. Pelagic prey fish diversity continues to be low since a single species, Alewife, dominates the catch. Deepwater Sculpin were the most abundant benthic prey fish in 2017 because Round Goby abundance declined sharply from 2016. Slimy Sculpin density continued to decline and the 2017 biomass index for US waters was the lowest ever observed. Prior to Round Goby proliferation, juvenile Slimy Sculpin comprised ~10% of the Slimy Sculpin catch, but

  10. Genetic diversity and population structure in contemporary house sparrow populations along an urbanization gradient

    OpenAIRE

    Vangestel, C; Mergeay, Joachim; Dawson, D. A; Callens, T; Vandomme, V; Lens, L

    2012-01-01

    House sparrow (Passer domesticus) populations have suffered major declines in urban as well as rural areas, while remaining relatively stable in suburban ones. Yet, to date no exhaustive attempt has been made to examine how, and to what extent, spatial variation in population demography is reflected in genetic population structuring along contemporary urbanization gradients. Here we use putatively neutral microsatellite loci to study if and how genetic variation can be partitioned in a hierar...

  11. Always chew your food: freshwater stingrays use mastication to process tough insect prey.

    Science.gov (United States)

    Kolmann, Matthew A; Welch, Kenneth C; Summers, Adam P; Lovejoy, Nathan R

    2016-09-14

    Chewing, characterized by shearing jaw motions and high-crowned molar teeth, is considered an evolutionary innovation that spurred dietary diversification and evolutionary radiation of mammals. Complex prey-processing behaviours have been thought to be lacking in fishes and other vertebrates, despite the fact that many of these animals feed on tough prey, like insects or even grasses. We investigated prey capture and processing in the insect-feeding freshwater stingray Potamotrygon motoro using high-speed videography. We find that Potamotrygon motoro uses asymmetrical motion of the jaws, effectively chewing, to dismantle insect prey. However, CT scanning suggests that this species has simple teeth. These findings suggest that in contrast to mammalian chewing, asymmetrical jaw action is sufficient for mastication in other vertebrates. We also determined that prey capture in these rays occurs through rapid uplift of the pectoral fins, sucking prey beneath the ray's body, thereby dissociating the jaws from a prey capture role. We suggest that the decoupling of prey capture and processing facilitated the evolution of a highly kinetic feeding apparatus in batoid fishes, giving these animals an ability to consume a wide variety of prey, including molluscs, fishes, aquatic insect larvae and crustaceans. We propose Potamotrygon as a model system for understanding evolutionary convergence of prey processing and chewing in vertebrates. © 2016 The Author(s).

  12. Benefits of Group Foraging Depend on Prey Type in a Small Marine Predator, the Little Penguin.

    Science.gov (United States)

    Sutton, Grace J; Hoskins, Andrew J; Arnould, John P Y

    2015-01-01

    Group foraging provides predators with advantages in over-powering prey larger than themselves or in aggregating small prey for efficient exploitation. For group-living predatory species, cooperative hunting strategies provide inclusive fitness benefits. However, for colonial-breeding predators, the benefit pay-offs of group foraging are less clear due to the potential for intra-specific competition. We used animal-borne cameras to determine the prey types, hunting strategies, and success of little penguins (Eudyptula minor), a small, colonial breeding air-breathing marine predator that has recently been shown to display extensive at-sea foraging associations with conspecifics. Regardless of prey type, little penguins had a higher probability of associating with conspecifics when hunting prey that were aggregated than when prey were solitary. In addition, success was greater when individuals hunted schooling rather than solitary prey. Surprisingly, however, success on schooling prey was similar or greater when individuals hunted on their own than when with conspecifics. These findings suggest individuals may be trading-off the energetic gains of solitary hunting for an increased probability of detecting prey within a spatially and temporally variable prey field by associating with conspecifics.

  13. Prey selection by Bengal Tiger Panthera tigris tigris (Mammalia: Carnivora: Felidae of Chitwan National Park, Nepal

    Directory of Open Access Journals (Sweden)

    Saneer Lamichhane

    2015-11-01

    Full Text Available Prey selection by tiger in Chitwan National Park, Nepal was studied from 77 tiger scats that contained the remains of principal prey species.  The scats were collected from January to March 2010.  Government reports on herbivore population in Chitwan provided the base data on density of principal prey species.  In order to understand prey selectivity, the observed proportion of prey species in the scats were compared with the expected proportion derived from density estimates.  The observed scat frequency of Sambar, Hog Deer and Wild Boar was found to be greater than the estimated frequency, and the reverse was true for Chital and Muntjac.  The average weight of the principal prey species killed was 84 kg. According to our results, Chital and Sambar constituted the bulk (82.07%, and Hog Deer, Wild Boar, and Muntjac constituted 17.93% of the tiger diet.  Sambar contributed the largest bulk (43.75% of prey composition, but Chital constituted the relatively most killed (50.36% prey species.  The present study makes a contribution to an understanding of the status of prey composition in tiger scat in Chitwan during the year 2010.  The study also highlights that both large and medium sized prey are important for the conservation of tiger in Chitwan National Park. 

  14. A specialized araneophagic predator's short-term nutrient utilization depends on the macronutrient content of prey rather than on prey taxonomic affiliation

    DEFF Research Database (Denmark)

    Toft, Søren; Li, Daiqin; Mayntz, David

    2010-01-01

    rate of high-protein flies than of high-lipid flies and spiders but, after 5 days of feeding, there is no significant difference in growth between treatments, and the diets lead to significant changes in the macronutrient composition of P. quei as a result of variable extraction and utilization...... of the prey. The short-term utilization of spider prey is similar to that of high-lipid flies and both differ in several respects from the utilization of high-protein flies. Thus, the short-term nutrient utilization is better explained by prey macronutrient content than by whether the prey is a spider or not....... The results suggest that spider prey may have a more optimal macronutrient composition for P. quei and that P. quei does not depend on spider-specific substances....

  15. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia

    Energy Technology Data Exchange (ETDEWEB)

    Millett, J., E-mail: j.millett@lboro.ac.uk [Centre for Hydrological and Ecosystem Science, Department of Geography, Loughborough University, Loughborough LE11 3TU (United Kingdom); Foot, G.W. [Centre for Hydrological and Ecosystem Science, Department of Geography, Loughborough University, Loughborough LE11 3TU (United Kingdom); Svensson, B.M. [Department of Plant Ecology and Evolution, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala (Sweden)

    2015-04-15

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant–prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. - Highlights: • We measured nutrition of the carnivorous plant Drosera rotundifolia across Europe. • We measured tissue nutrient concentrations and prey and root N uptake at 16 sites. • Tissue N concentrations were a product of root N availability and prey N uptake. • N deposition reduced the maximum amount of N derived from prey. • N deposition reduced the strength of a

  16. Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia

    International Nuclear Information System (INIS)

    Millett, J.; Foot, G.W.; Svensson, B.M.

    2015-01-01

    Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant–prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific. - Highlights: • We measured nutrition of the carnivorous plant Drosera rotundifolia across Europe. • We measured tissue nutrient concentrations and prey and root N uptake at 16 sites. • Tissue N concentrations were a product of root N availability and prey N uptake. • N deposition reduced the maximum amount of N derived from prey. • N deposition reduced the strength of a

  17. Seasonal foraging ecology of non-migratory cougars in a system with migrating prey.

    Directory of Open Access Journals (Sweden)

    L Mark Elbroch

    Full Text Available We tested for seasonal differences in cougar (Puma concolor foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus and moose (Alces alces than females, while females killed greater proportions of bighorn sheep (Ovis canadensis, pronghorn (Antilocapra americana, mule deer (Odocoileus hemionus and small prey than males. Kill rates did not vary by season or between males and females. In winter, cougars were more likely to kill prey on the landscape as: 1 elevation decreased, 2 distance to edge habitat decreased, 3 distance to large bodies of water decreased, and 4 steepness increased, whereas in summer, cougars were more likely to kill in areas as: 1 elevation decreased, 2 distance to edge habitat decreased, and 3 distance from large bodies of water increased. Our work highlighted that seasonal prey selection exhibited by stationary carnivores in systems with migratory prey is not only driven by changing prey vulnerability, but also by changing prey abundances. Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer. Nevertheless, cougar predation on rare ungulates also appeared to be influenced by individual prey selection.

  18. Life-stage differences in spatial genetic structure in an irruptive forest insect: implications for dispersal and spatial synchrony

    Science.gov (United States)

    Patrick M.A. James; Barry Cooke; Bryan M.T. Brunet; Lisa M. Lumley; Felix A.H. Sperling; Marie-Josee Fortin; Vanessa S. Quinn; Brian R. Sturtevant

    2015-01-01

    Dispersal determines the flux of individuals, energy and information and is therefore a key determinant of ecological and evolutionary dynamics. Yet, it remains difficult to quantify its importance relative to other factors. This is particularly true in cyclic populations in which demography, drift and dispersal contribute to spatio-temporal variability in genetic...

  19. Eastern wood-pewee (Contopus virens) breeding demography across a gradient of savanna, woodland, and forest in the Missouri Ozarks

    Science.gov (United States)

    Sarah W. Kendrick; Frank R. Thompson; Jennifer L. Reidy

    2013-01-01

    Better knowledge of bird response to savanna and woodland restoration is needed to inform management of these communities. We related temporal and habitat variables to breeding demography and densities of the Eastern Wood-Pewee (Contopus virens) across a gradient of savanna, woodland, and forest. We determined nest success, clutch size, young fledged...

  20. Comparison of multimammate mouse (Mastomys natalensis) demography in monoculture and mosaic agricultural habitat

    DEFF Research Database (Denmark)

    Sluydts, Vincent; Davis, Stephen; Mercelis, Saskia

    2009-01-01

    . The multimammate mouse (Mastomys natalensis) is a major pest in rural areas throughout sub-Saharan Africa. It appears difficult to control since it has an opportunistic diet and the capacity for explosive population growth. We compared demographic rates between a population in an extensive maize monoculture...... in the mosaic compared to the monoculture. The probability of capture was higher in the mosaic structured grid for both the subadult and adult part of the population. The model selection procedure demonstrated that a model without an effect of habitat in both survival and seniority received most support from...... the data. No differences in the multimammate mouse demography between the monoculture and mosaic structured habitat were observed which had a substantial impact on population dynamics. This means that rodent management options in both agricultural systems could focus on the same aspects of rodent ecology....

  1. A non-marine source of variability in Adélie Penguin demography

    Science.gov (United States)

    Fraser, William R.; Patterson-Fraser, Donna L.; Ribic, Christine; Schofield, Oscar; Ducklow, Hugh

    2013-01-01

    A primary research objective of the Palmer Long Term Ecological Research (LTER) program has been to identify and understand the factors that regulate the demography of Adélie penguins (Pygoscelis adeliae). In this context, our work has been focused on variability in the marine environment on which this species depends for virtually all aspects of its life history (Ainley, 2002). As we show here, however, there are patterns evident in the population dynamics of Adélie penguins that are better explained by variability in breeding habitat quality rather than by variability in the marine system. Interactions between the geomorphology of the terrestrial environment that, in turn, affect patterns of snow deposition, drive breeding habitat quality.

  2. A work bibliography on native food consumption, demography and lifestyle. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Murray, C.E.; Lee, W.J.

    1992-12-01

    The purpose of this report is to provide a bibliography for the Native American tribe participants in the Hanford Environmental Dose Reconstruction (HEDR) Project to use. The HEDR Project`s primary objective is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s Hanford Site near Richland, Washington. Eight Native American tribes are responsible for estimating daily and seasonal consumption of traditional foods, demography, and other lifestyle factors that could have affected the radiation dose received by tribal members. This report provides a bibliography of recorded accounts that tribal researchers may use to verify their estimates. The bibliographic citations include references to information on the specific tribes, Columbia River plateau ethnobotany, infant feeding practices and milk consumption, nutritional studies and radiation, tribal economic and demographic characteristics (1940--1970), research methods, primary sources from the National Archives, regional archives, libraries, and museums.

  3. Owned dog ecology and demography in Villa de Tezontepec, Hidalgo, Mexico.

    Science.gov (United States)

    Kisiel, Luz Maria; Jones-Bitton, Andria; Sargeant, Jan M; Coe, Jason B; Flockhart, D T Tyler; Reynoso Palomar, Alejandro; Canales Vargas, Erick J; Greer, Amy L

    2016-12-01

    Dog overpopulation in developing countries has negative implications for the health and safety of people, including the transmission of zoonotic diseases, physical attacks and intimidation to humans and animals, as well as impacts on canine welfare. Understanding the ecology and demographic characteristics of a dog population can help in the planning and monitoring of canine population control programs. Little data exist regarding demography and dynamics of domestic dog populations in semi-urban areas in Mexico. A cross-sectional study was carried out between October 21 and November 7, 2015, to characterize the dog ecology and demography in Villa de Tezontepec, Hidalgo, Mexico. A face-to-face survey was used to collect data from randomly selected households in four contiguous communities using stratified two-stage cluster sampling. Within each household, adults answered questions related to their dogs and their experiences with dog bites and aggression. A total of 328 households were interviewed, representing a participation rate of 90.9% (328/361) and 1,450 people. Approximately 65.2% of the households owned one or more dogs, with a mean of 1.3 (SD=1.5) and 2.0 (SD=1.5) owned dogs in all participant households and dog-owning households, respectively. The human: owned dog ratio for all participant households was 3.4:1 (1450/428), and for the dog-owning households was 2.3:1 (984/428). The owned dog male: female ratio was 1.4:1 (249/179). Approximately 74.4% (95.0% CI=69.8% - 78.7%) of the owned dogs were older than one year (mean age: 2.9 years; SD=2.5). The mean age of owned female dogs at first litter was 1.9 years (SD=1.2) and the mean litter size was 4.2 puppies (SD=2.1). Approximately 36.9% (95.0% CI=31.8% - 46.4%) of the females were spayed, and 14.1% (95.0% CI=10.7% - 19.7%) of the males were neutered. Only 44.9% (95.0% CI=40.1% - 49.7%) were always confined when unsupervised. Approximately 84.4% (95.0% CI=80.6% - 87.7%) were reported to have been vaccinated

  4. Leaf development and demography explain photosynthetic seasonality in Amazon evergreen forests

    Science.gov (United States)

    Wu, Jin; Albert, Lauren; Lopes, Aline; Restrepo-Coupe, Natalia; Hayek, Matthew; Wiedemann, Kenia T.; Guan, Kaiyu; Stark, Scott C.; Christoffersen, Bradley; Prohaska, Neill; Tavares, Julia V.; Marostica, Suelen; Kobayashi, Hideki; Ferreira, Maurocio L.; Campos, Kleber Silva; da Silva, Rodrigo; Brando, Paulo M.; Dye, Dennis G.; Huxman, Travis E.; Huete, Alfredo; Nelson, Bruce; Saleska, Scott

    2016-01-01

    In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change.

  5. Perceiving the algae: How feeding-current feeding copepods detect their nonmotile prey

    DEFF Research Database (Denmark)

    Goncalves, Rodrigo J.; Kiørboe, Thomas

    2015-01-01

    demonstrate that (1) long-range chemical detection is incompatible with known algal leakage rates and reasonable assumptions of sensitivity, (2) that near-field chemical detection is constrained by diffusion across the boundary layer of the sensor and takes longer than observed near-contact times, and (3......Feeding-current feeding copepods detect and capture prey individually, but the mechanism by which nonmotile prey is detected has been unclear. Early reports that copepods detect phytoplankton prey at distances of one body length or more led to the hypothesis that solutes leaking from the prey would......) that most reported detection distances are well predicted by models of fluid mechanical signal generation and detection. We conclude that near-field mechanoreception is the common prey detection mode in pelagic copepods. Prey detection distances are thus governed mainly by the reach of the feeding...

  6. Availability and abundance of prey for the red-cockaded woodpecker.

    Energy Technology Data Exchange (ETDEWEB)

    Hanula, James, L.; Horn, Scott

    2004-12-31

    Red-cockaded woodpecker; Road to Recovery. Proceedings of the 4th Red-cockaded woodpecker Symposium. Ralph Costa and Susan J. Daniels, eds. Savannah, Georgia. January, 2003. Chapter 11. Prey, Fire, and Community Ecology. Pp 633-645. Abstract: Over a 10-year period we investigated red-cockaded woodpecker (Picoides borealis) prey use, sources of prey, prey distribution within trees and stands, and how forest management decisions affect prey abundance in South Carolina, Alabama, Georgia and Florida. Cameras were operated at 31 nest cavities to record nest visits with prey in 4 locations that ranged in foraging habitat from pine stands established in old fields to an old-growth stand in South Georgia. Examination of nearly 12,000 photographs recorded over 5 years revealed that, although red-cockaded woodpeckers used over 40 arthropods for food, the majority of the nestling diet is comprised of a relatively small number of common arthropods.

  7. Genetic demographic networks: Mathematical model and applications.

    Science.gov (United States)

    Kimmel, Marek; Wojdyła, Tomasz

    2016-10-01

    Recent improvement in the quality of genetic data obtained from extinct human populations and their ancestors encourages searching for answers to basic questions regarding human population history. The most common and successful are model-based approaches, in which genetic data are compared to the data obtained from the assumed demography model. Using such approach, it is possible to either validate or adjust assumed demography. Model fit to data can be obtained based on reverse-time coalescent simulations or forward-time simulations. In this paper we introduce a computational method based on mathematical equation that allows obtaining joint distributions of pairs of individuals under a specified demography model, each of them characterized by a genetic variant at a chosen locus. The two individuals are randomly sampled from either the same or two different populations. The model assumes three types of demographic events (split, merge and migration). Populations evolve according to the time-continuous Moran model with drift and Markov-process mutation. This latter process is described by the Lyapunov-type equation introduced by O'Brien and generalized in our previous works. Application of this equation constitutes an original contribution. In the result section of the paper we present sample applications of our model to both simulated and literature-based demographies. Among other we include a study of the Slavs-Balts-Finns genetic relationship, in which we model split and migrations between the Balts and Slavs. We also include another example that involves the migration rates between farmers and hunters-gatherers, based on modern and ancient DNA samples. This latter process was previously studied using coalescent simulations. Our results are in general agreement with the previous method, which provides validation of our approach. Although our model is not an alternative to simulation methods in the practical sense, it provides an algorithm to compute pairwise

  8. Diagnosing the dangerous demography of manta rays using life history theory

    Directory of Open Access Journals (Sweden)

    Nicholas K. Dulvy

    2014-05-01

    Full Text Available Background. The directed harvest and global trade in the gill plates of mantas, and devil rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography within the context of other sharks and rays.Methods. Despite the limited availability of data, we use life history theory and comparative analysis to estimate the intrinsic risk of extinction (as indexed by the maximum intrinsic rate of population increase rmax for a typical generic manta ray using a variant of the classic Euler–Lotka demographic model. This model requires only three traits to calculate the maximum intrinsic population growth rate rmax: von Bertalanffy growth rate, annual pup production and age at maturity. To account for the uncertainty in life history parameters, we created plausible parameter ranges and propagate these uncertainties through the model to calculate a distribution of the plausible range of rmax values.Results. The maximum population growth rate rmax of manta ray is most sensitive to the length of the reproductive cycle, and the median rmax of 0.116 year−1 95th percentile [0.089–0.139] is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information.Discussion. In common with other unprotected, unmanaged, high-value large-bodied sharks and rays the combination of very low population growth rates of manta rays, combined with the high value of their gill rakers and the international nature of trade, is highly likely to lead to rapid depletion and potential local extinction unless a rapid conservation management response occurs worldwide. Furthermore, we show that it is possible to derive important insights into the demography extinction risk of data-poor species using well-established life

  9. Coupling mammalian demography to climate through satellite time series of plant phenology

    Science.gov (United States)

    Stoner, D.; Sexton, J. O.; Nagol, J. R.; Ironside, K.; Choate, D.; Longshore, K.; Edwards, T., Jr.

    2016-12-01

    The seasonality of plant productivity governs the demography of primary and secondary consumers, and in arid ecosystems primary production is constrained by water availability. We relate the behavior, demography, and spatial distribution of large mammalian herbivores and their principal predator to remotely sensed indices of climate and vegetation across the western United States from 2000-2014. Terrain and plant community composition moderate the effects of climatological drought on primary productivity, resulting in spatial variation in ecosystem susceptibility to water stress. Herbivores track these patterns through habitat selection during key periods such as birthing and migration. Across a broad climatological gradient, timing of the start of growing season explains 75% of the variation in herbivore birth timing and 56% of the variation in neonatal survival rates. Initiation of autumn migration corresponds with the end of the growing season. Although indirectly coupled to primary production, carnivore home range size and population density are strongly correlated with plant productivity and growing-season length. Satellite measures of green reflectance during the peak of the growing season explain over 84% of the variation in carnivore home range size and 59% of the variation in density. Climate projections for the western United States predict warming temperatures and shifts in the timing and form of precipitation. Our analyses suggest that increased climatological variability will contribute to fluctuations in the composition and phenology of plant communities. These changes will propagate through consumer trophic levels, manifesting as increased home range area, shifts in the timing of migration, and greater volatility in large mammal populations. Combined with expansion and amplification of human land uses, these changes will likely have economic implications stemming from increased human-wildlife conflict and loss of ecosystem services.

  10. Diagnosing the dangerous demography of manta rays using life history theory.

    Science.gov (United States)

    Dulvy, Nicholas K; Pardo, Sebastián A; Simpfendorfer, Colin A; Carlson, John K

    2014-01-01

    Background. The directed harvest and global trade in the gill plates of mantas, and devil rays, has led to increased fishing pressure and steep population declines in some locations. The slow life history, particularly of the manta rays, is cited as a key reason why such species have little capacity to withstand directed fisheries. Here, we place their life history and demography within the context of other sharks and rays. Methods. Despite the limited availability of data, we use life history theory and comparative analysis to estimate the intrinsic risk of extinction (as indexed by the maximum intrinsic rate of population increase r max) for a typical generic manta ray using a variant of the classic Euler-Lotka demographic model. This model requires only three traits to calculate the maximum intrinsic population growth rate r max: von Bertalanffy growth rate, annual pup production and age at maturity. To account for the uncertainty in life history parameters, we created plausible parameter ranges and propagate these uncertainties through the model to calculate a distribution of the plausible range of r max values. Results. The maximum population growth rate r max of manta ray is most sensitive to the length of the reproductive cycle, and the median r max of 0.116 year(-1) 95th percentile [0.089-0.139] is one of the lowest known of the 106 sharks and rays for which we have comparable demographic information. Discussion. In common with other unprotected, unmanaged, high-value large-bodied sharks and rays the combination of very low population growth rates of manta rays, combined with the high value of their gill rakers and the international nature of trade, is highly likely to lead to rapid depletion and potential local extinction unless a rapid conservation management response occurs worldwide. Furthermore, we show that it is possible to derive important insights into the demography extinction risk of data-poor species using well-established life history theory.

  11. Demography and sex work characteristics of female sex workers in India

    Directory of Open Access Journals (Sweden)

    McPherson Sam

    2006-04-01

    Full Text Available Abstract Background The majority of sex work in India is clandestine due to unfavorable legal environment and discrimination against female sex workers (FSWs. We report data on who these women are and when they get involved with sex work that could assist in increasing the reach of HIV prevention activities for them. Methods Detailed documentation of demography and various aspects of sex work was done through confidential interviews of 6648 FSWs in 13 districts in the Indian state of Andhra Pradesh. The demography of FSWs was compared with that of women in the general population. Results A total of 5010 (75.4%, 1499 (22.5%, and 139 (2.1% street-, home-, and brothel-based FSWs, respectively, participated. Comparison with women of Andhra Pradesh revealed that the proportion of those aged 20–34 years (75.6%, belonging to scheduled caste (35.3% and scheduled tribe (10.5%, illiterate (74.7%, and of those separated/divorced (30.7% was higher among FSWs (p 5 years were more likely to be non-street-based FSWs, illiterate, living in small urban towns, and to have started sex work between 12–15 years of age. The mean age at starting sex work (21.7 years and gap between the first vaginal intercourse and the first sexual intercourse in exchange for money (6.6 years was lower for FSWs in the rural areas as compared with those in large urban areas (23.9 years and 8.8 years, respectively. Conclusion These data highlight that women struggling with illiteracy, lower social status, and less economic opportunities are especially vulnerable to being infected by HIV, as sex work may be one of the few options available to them to earn money. Recommendations for actions are made for long-term impact on reducing the numbers of women being infected by HIV in addition to the current HIV prevention efforts in India.

  12. Demography and sex work characteristics of female sex workers in India

    Science.gov (United States)

    Dandona, Rakhi; Dandona, Lalit; Kumar, G Anil; Gutierrez, Juan Pablo; McPherson, Sam; Samuels, Fiona; Bertozzi, Stefano M

    2006-01-01

    Background The majority of sex work in India is clandestine due to unfavorable legal environment and discrimination against female sex workers (FSWs). We report data on who these women are and when they get involved with sex work that could assist in increasing the reach of HIV prevention activities for them. Methods Detailed documentation of demography and various aspects of sex work was done through confidential interviews of 6648 FSWs in 13 districts in the Indian state of Andhra Pradesh. The demography of FSWs was compared with that of women in the general population. Results A total of 5010 (75.4%), 1499 (22.5%), and 139 (2.1%) street-, home-, and brothel-based FSWs, respectively, participated. Comparison with women of Andhra Pradesh revealed that the proportion of those aged 20–34 years (75.6%), belonging to scheduled caste (35.3%) and scheduled tribe (10.5%), illiterate (74.7%), and of those separated/divorced (30.7%) was higher among FSWs (p 5 years were more likely to be non-street-based FSWs, illiterate, living in small urban towns, and to have started sex work between 12–15 years of age. The mean age at starting sex work (21.7 years) and gap between the first vaginal intercourse and the first sexual intercourse in exchange for money (6.6 years) was lower for FSWs in the rural areas as compared with those in large urban areas (23.9 years and 8.8 years, respectively). Conclusion These data highlight that women struggling with illiteracy, lower social status, and less economic opportunities are especially vulnerable to being infected by HIV, as sex work may be one of the few options available to them to earn money. Recommendations for actions are made for long-term impact on reducing the numbers of women being infected by HIV in addition to the current HIV prevention efforts in India. PMID:16615869

  13. Foraging mode and prey size spectra of suspension-feeding copepods and other zooplankton

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2016-01-01

    Prey size spectra of suspension-feeding zooplankton may be predicted from foraging mode and a mechanistic understanding of prey perception and capture. I examine this for suspension-feeding copepods where 2 foraging modes can be distinguished: ambush feeding and active (i.e. cruising and feeding-...... the prediction. I also make qualitative predictions of food size spectra in zooplankton with other prey perception mechanisms that accord with observations....

  14. Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)

    Science.gov (United States)

    Bom, Roeland A.; Fijen, Thijs P. M.; van Gils, Jan A.

    2018-01-01

    Foragers whose energy intake rate is constrained by search and handling time should, according to the contingency model (CM), select prey items whose profitability exceeds or equals the forager’s long-term average energy intake rate. This rule does not apply when prey items are found and ingested at a higher rate than the digestive system can process them. According to the digestive rate model (DRM), foragers in such situations should prefer prey with the highest digestive quality, instead of the highest profitability. As the digestive system fills up, the limiting constraint switches from ingestion rate to digestion rate, and prey choice is expected to change accordingly for foragers making decisions over a relative short time window. We use these models to understand prey choice in crab plovers (Dromas ardeola), preying on either small burrowing crabs that are swallowed whole (high profitability, but potentially inducing a digestive constraint) or on larger swimming crabs that are opened to consume only the flesh (low profitability, but easier to digest). To parameterize the CM and DRM, we measured energy content, ballast mass and handling times for different sized prey, and the birds’ digestive capacity in three captive individuals. Subsequently, these birds were used in ad libitum experiments to test if they obeyed the rules of the CM or DRM. We found that crab plovers with an empty stomach mainly chose the most profitable prey, matching the CM. When stomach fullness increased, the birds switched their preference from the most profitable prey to the highest-quality prey, matching the predictions of the DRM. This shows that prey choice is context dependent, affected by the stomach fullness of an animal. Our results suggest that prey choice experiments should be carefully interpreted, especially under captive conditions as foragers often ‘fill up’ in the course of feeding trials. PMID:29641542

  15. Do top predators cue on sound production by mesopelagic prey?

    Science.gov (United States)

    Baumann-Pickering, S.; Checkley, D. M., Jr.; Demer, D. A.

    2016-02-01

    Deep-scattering layer (DSL) organisms, comprising a variety of mesopelagic fishes, and squids, siphonophores, crustaceans, and other invertebrates, are preferred prey for numerous large marine predators, e.g. cetaceans, seabirds, and fishes. Some of the DSL species migrate from depth during daylight to feed near the surface at night, transitioning during dusk and dawn. We investigated if any DSL organisms create sound, particularly during the crepuscular periods. Over several nights in summer 2015, underwater sound was recorded in the San Diego Trough using a high-frequency acoustic recording package (HARP, 10 Hz to 100 kHz), suspended from a drifting surface float. Acoustic backscatter from the DSL was monitored nearby using a calibrated multiple-frequency (38, 70, 120, and 200 kHz) split-beam echosounder (Simrad EK60) on a small boat. DSL organisms produced sound, between 300 and 1000 Hz, and the received levels were highest when the animals migrated past the recorder during ascent and descent. The DSL are globally present, so the observed acoustic phenomenon, if also ubiquitous, has wide-reaching implications. Sound travels farther than light or chemicals and thus can be sensed at greater distances by predators, prey, and mates. If sound is a characteristic feature of pelagic ecosystems, it likely plays a role in predator-prey relationships and overall ecosystem dynamics. Our new finding inspires numerous questions such as: Which, how, and why have DSL organisms evolved to create sound, for what do they use it and under what circumstances? Is sound production by DSL organisms truly ubiquitous, or does it depend on the local environment and species composition? How may sound production and perception be adapted to a changing environment? Do predators react to changes in sound? Can sound be used to quantify the composition of mixed-species assemblages, component densities and abundances, and hence be used in stock assessment or predictive modeling?

  16. Quenching behaviour for a singular predator–prey model

    International Nuclear Information System (INIS)

    Ducrot, Arnaud; Guo, Jong-Shenq

    2012-01-01

    In this paper, we study the quenching behaviour for a system of two reaction–diffusion equations arising in the modelling of the spatio-temporal interaction of prey and predator populations in fragile environment. We first provide some sufficient conditions on the initial data to have finite time quenching. Then we classify the initial data to distinguish type I quenching and type II quenching, by introducing a delicate energy functional along with the help of some a priori estimates. Finally, we present some results on the quenching set. It can be a singleton, the whole domain, or a compact subset of the domain

  17. Ineffective crypsis in a crab spider: a prey community perspective

    OpenAIRE

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2009-01-01

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts u...

  18. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Dominant Glint Based Prey Localization in Horseshoe Bats: A Possible Strategy for Noise Rejection

    OpenAIRE

    Vanderelst, Dieter; Reijniers, Jonas; Firzlaff, Uwe; Peremans, Herbert

    2011-01-01

    Rhinolophidae or Horseshoe bats emit long and narrowband calls. Fluttering insect prey generates echoes in which amplitude and frequency shifts are present, i.e. glints. These glints are reliable cues about the presence of prey and also encode certain properties of the prey. In this paper, we propose that these glints, i.e. the dominant glints, are also reliable signals upon which to base prey localization. In contrast to the spectral cues used by many other bats, the localization cues in Rhi...

  20. Prey preferences of aquatic insects: potential implications for the regulation of wetland mosquitoes.

    Science.gov (United States)

    Saha, N; Aditya, G; Saha, G K

    2014-03-01

    Wetlands are potential sites for mosquito breeding and are thus important in the context of public health. The use of chemical and microbial controls is constrained in wetlands in view of their potential impact on the diverse biota. Biological control using generalist aquatic insects can be effective, provided a preference for mosquito larvae is exhibited. The mosquito prey preferences of water bugs and larvae of odonate species were evaluated using chironomid larvae, fish fingerlings and tadpoles as alternative prey. Manly's selectivity (αi ) values with 95% confidence intervals (CIs) were estimated to judge prey preference patterns. Multivariate analysis of variance (manova) and standardized canonical coefficients were used to test the effects of density on prey selectivity. The αi values indicated a significant preference (P insect predators tested for mosquito larvae over the alternative prey as a density-dependent function. On a comparative scale, chironomid larvae had the highest impact as alternative prey. In a multiple-prey experiment, predators showed a similar pattern of preference for mosquito larvae over alternative prey, reflecting a significant (P insect predators can effectively reduce mosquito density in the presence of multiple alternative prey. © 2013 The Royal Entomological Society.

  1. Prey and mound disassembly, manipulation and transport by fire ant collectives

    Science.gov (United States)

    Dutta, Bahnisikha; Monaenkova, Daria; Goodisman, Michael A.; Goldman, Daniel

    Fire ants inhabit subterranean nests covered by a hemispherical mound of soil permeated by narrow ( 1 body length diameter) tunnels. Fire ants can use their mound for long-term food storage [Gayahan &Tschinkel, J. Insect Sci.,2008]. Since mound tunnels are narrow, we expect that in addition to prey manipulation, mound reconfiguration could also be an important aspect of the food storage strategy. Ant colonies collected from wild were allowed to build nests in containers filled with clay soil in the laboratory. These colonies were offered diverse prey embedded with lead markers, including mealworms, crickets and shrimp. Ant-prey-soil interactions on the nest surface were recorded using overhead video and subsurface using x-ray imaging. Individual ants involved in prey storage exhibited three distinct behaviors: prey maneuvering, prey dissection and mound reconfiguration. Small prey (e.g. mealworms) were collectively carried intact into the mound through a tunnel, and then disassembled within the mound. Larger prey (e.g. shrimp) were dismantled into small pieces above the surface and carried to mound tunnels. The bodies of hard medium-sized prey (e.g. crickets) were buried after limb removal and then disassembled and moved into tunnels. Soil reconfiguration occurred in all cases.

  2. Process-based models of feeding and prey selection in larval fish

    DEFF Research Database (Denmark)

    Fiksen, O.; MacKenzie, Brian

    2002-01-01

    believed to be important to prey selectivity and environmental regulation of feeding in fish. We include the sensitivity of prey to the hydrodynamic signal generated by approaching larval fish and a simple model of the potential loss of prey due to turbulence whereby prey is lost if it leaves...... jig dry wt l(-1). The spatio-temporal fluctuation of turbulence (tidal cycle) and light (sun height) over the bank generates complex structure in the patterns of food intake of larval fish, with different patterns emerging for small and large larvae....

  3. Modelling the attack success of planktonic predators: patterns and mechanisms of prey size selectivity

    DEFF Research Database (Denmark)

    Caparroy, P.; Thygesen, Uffe Høgsbro; Visser, Andre

    2000-01-01

    of being captured. By combining the attack success model with previously published hydrodynamic models of predator and prey perception, we examine how predator foraging behaviour and prey perceptive ability affect the size spectra of encountered and captured copepod prey. We examine food size spectra of (i......) a rheotactic cruising predator, (ii) a suspension-feeding hovering copepod and (iii) a larval fish. For rheotactic predators such as carnivorous copepods, a central assumption of the model is that attack is triggered by prey escape reaction, which in turn depends on the deformation rate of the fluid created...

  4. Chlorophacinone residues in mammalian prey at a black-tailed prairie dog colony

    Science.gov (United States)

    Vyas, Nimish B.; Hulse, Craig S.; Rice, Clifford P.

    2012-01-01

    Black-tailed prairie dogs (BTPDs), Cynomys ludovicianus, are an important prey for raptors; therefore, the use of the rodenticide Rozol (0.005% chlorophacinone active ingredient) to control BTPDs raises concern for secondary poisonings resulting from the consumption of contaminated prey by raptors. In the present study, the authors observed Rozol exposure and adverse effects to mammalian prey on 11 of 12 search days of the study. Mammalian hepatic chlorophacinone residues ranged from 0.44 to 7.56 µg/g. Poisoned prey availability was greater than previously reported.

  5. Foraging behavior of larval cod ( Gadus morhua ) influenced by prey density and hunger

    DEFF Research Database (Denmark)

    Munk, Peter

    1995-01-01

    activity, prey selectivity, and hunger in a variable prey environment. Gadus morhua eggs were collected in March 1992 and 1993 from the Kattegat area, Denmark, fertilised and incubated in the laboratory. After hatching, the larvae were transferred to rearing tanks of 172 litres. The behaviour of larvae (6...... their prey size selectivity. Behavioural response was to a large degree determined by the level of hunger, represented by the number of newly ingested prey in the gut. The findings show that cod larvae have a flexible response to changes in feeding conditions and imply that larvae can grow and survive even...

  6. Early Pleistocene lineages of Bagre bagre (Linnaeus, 1766 (Siluriformes: Ariidae, from the Atlantic coast of South America, with insights into the demography and biogeography of the species

    Directory of Open Access Journals (Sweden)

    Wemerson C. da Silva

    Full Text Available ABSTRACT Coastal and marine environments are characterized by a lack of evident physical barriers or geographic isolation, and it may be difficult to understand how divergence can arise and be sustained in marine environments. The identification of 'soft' barriers is a crucial step towards the understanding of gene flow in marine environments. The marine catfishes of the family Ariidae are a demersal group with restricted migratory behavior, no pelagic larval stages, and mechanisms of larval retention, representing a potentially useful model for the understanding of historical processes of allopatric speciation in the marine environment. In the present study, two lineages of the Coco sea catfish, Bagre bagre , were recognized from their complete segregation at both mitochondrial and morphological levels. One lineage is distributed between Venezuela and the northern coast of Brazil, including the semiarid northeast coast, while the second lineage is found on the eastern coast of Brazil, including the humid northeast coast. Based on distribution area, habitats preference, and genetic variability, inferences are made in relation to biogeography and demography of lineages in Atlantic coast of South America.

  7. Coexistence of structured populations with size-based prey selection

    DEFF Research Database (Denmark)

    Hartvig, Martin; Andersen, Ken Haste

    2013-01-01

    Abstract Species with a large adult-offspring size ratio and a preferred predator–prey mass ratio undergo ontogenetic trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout life, resulting in different species-level interaction motifs depending on the ma......Abstract Species with a large adult-offspring size ratio and a preferred predator–prey mass ratio undergo ontogenetic trophic niche shift(s) throughout life. Trophic interactions between such species vary throughout life, resulting in different species-level interaction motifs depending...... on the maximum adult sizes and population size distributions. We explore the assembly and potential for coexistence of small communities where all species experience ontogenetic trophic niche shifts. The life-history of each species is described by a physiologically structured model and species identity...... there is a large scope for coexistence of two species, the scope for coexistence of three species is limited and we conclude that further trait differentiation is required for coexistence of more species-rich size-structured communities....

  8. Boundedness and permanence in a class of periodic time-dependent predator-prey system with prey dispersal and predator density-independence

    International Nuclear Information System (INIS)

    Zhang Long; Teng Zhidong

    2008-01-01

    In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients, in which the prey species can disperse among n patches, while the density-independent predator species is confined to one of the patches and cannot disperse. Sufficient conditions on the boundedness, permanence and existence of positive periodic solution for this system are established. The theoretical results are confirmed by a special example and numerical simulations

  9. Effects of dams on downstream molluscan predator-prey interactions in the Colorado River estuary.

    Science.gov (United States)

    Smith, Jansen A; Handley, John C; Dietl, Gregory P

    2018-05-30

    River systems worldwide have been modified for human use and the downstream ecological consequences are often poorly understood. In the Colorado River estuary, where upstream water diversions have limited freshwater input during the last century, mollusc remains from the last several hundred years suggest widespread ecological change. The once abundant clam Mulinia modesta has undergone population declines of approximately 94% and populations of predators relying on this species as a food source have probably declined, switched to alternative prey species or both. We distinguish between the first two hypotheses using a null model of predation preference to test whether M. modesta was preyed upon selectively by the naticid snail, Neverita reclusiana , along the estuary's past salinity gradient. To evaluate the third hypothesis, we estimate available prey biomass today and in the past, assuming prey were a limiting resource. Data on the frequency of drill holes-identifiable traces of naticid predation on prey shells-showed several species, including M. modesta , were preferred prey. Neverita reclusiana was probably able to switch prey. Available prey biomass also declined, suggesting the N. reclusiana population probably also declined. These results indicate a substantial change to the structure of the benthic food web. Given the global scale of water management, such changes have probably also occurred in many of the world's estuaries. © 2018 The Author(s).

  10. Penguin head movement detected using small accelerometers: a proxy of prey encounter rate.

    Science.gov (United States)

    Kokubun, Nobuo; Kim, Jeong-Hoon; Shin, Hyoung-Chul; Naito, Yasuhiko; Takahashi, Akinori

    2011-11-15

    Determining temporal and spatial variation in feeding rates is essential for understanding the relationship between habitat features and the foraging behavior of top predators. In this study we examined the utility of head movement as a proxy of prey encounter rates in medium-sized Antarctic penguins, under the presumption that the birds should move their heads actively when they encounter and peck prey. A field study of free-ranging chinstrap and gentoo penguins was conducted at King George Island, Antarctica. Head movement was recorded using small accelerometers attached to the head, with simultaneous monitoring for prey encounter or body angle. The main prey was Antarctic krill (>99% in wet mass) for both species. Penguin head movement coincided with a slow change in body angle during dives. Active head movements were extracted using a high-pass filter (5 Hz acceleration signals) and the remaining acceleration peaks (higher than a threshold acceleration of 1.0 g) were counted. The timing of head movements coincided well with images of prey taken from the back-mounted cameras: head movement was recorded within ±2.5 s of a prey image on 89.1±16.1% (N=7 trips) of images. The number of head movements varied largely among dive bouts, suggesting large temporal variations in prey encounter rates. Our results show that head movement is an effective proxy of prey encounter, and we suggest that the method will be widely applicable for a variety of predators.

  11. Intra-seasonal Strategies Based on Energy Budgets in a Dynamic Predator-Prey Game

    NARCIS (Netherlands)

    Staňková, K.; Abate, A.; Sabelis, M.W.; Křivan, V.; Zaccour, G.

    2013-01-01

    We propose a game-theoretical model to describe intra-seasonal predator-prey interactions between predatory mites (Acari: Phytoseiidae) and prey mites (also called fruit-tree red spider mites) (Acari: Tetranychidae) that feed on leaves of apple trees. Its parameters have been instantiated based on

  12. Clay Caterpillar Whodunit: A Customizable Method for Studying Predator-Prey Interactions in the Field

    Science.gov (United States)

    Curtis, Rachel; Klemens, Jeffrey A.; Agosta, Salvatore J.; Bartlow, Andrew W.; Wood, Steve; Carlson, Jason A.; Stratford, Jeffrey A.; Steele, Michael A.

    2013-01-01

    Predator-prey dynamics are an important concept in ecology, often serving as an introduction to the field of community ecology. However, these dynamics are difficult for students to observe directly. We describe a methodology that employs model caterpillars made of clay to estimate rates of predator attack on a prey species. This approach can be…

  13. Coexistence in a One-Predator, Two-Prey System with Indirect Effects

    Directory of Open Access Journals (Sweden)

    Renato Colucci

    2013-01-01

    Full Text Available We study the dynamics of a one-predator, two-prey system in which the predator has an indirect effect on the preys. We show that, in presence of the indirect effect term, the system admits coexistence of the three populations while, if we disregard it, at least one of the populations goes to extinction.

  14. Stomach fullness shapes prey choice decisions in crab plovers (Dromas ardeola)

    NARCIS (Netherlands)

    Gommer, Roy; Bom, Roeland A.; Fijen, Thijs P.M.; Gils, Van Jan A.

    2018-01-01

    Foragers whose energy intake rate is constrained by search and handling time should, according to the contingency model (CM), select prey items whose profitability exceeds or equals the forager’s long-term average energy intake rate. This rule does not apply when prey items are found and ingested at

  15. An impulsive predator-prey system with modified Leslie-Gower and Holling type II schemes

    International Nuclear Information System (INIS)

    Guo Hongjian; Song Xinyu

    2008-01-01

    An impulsive predator-prey system with modified Leslie-Gower and Holling-type II schemes is presented. By using the Floquet theory of impulsive equation and small amplitude perturbation method, the globally asymptotical stability of prey-free positive periodic solution and the permanence of system are discussed. The corresponding threshold conditions are obtained respectively. Finally, numerical simulations are given

  16. Recognising one's enemies : a functional approach to risk assessment by prey

    NARCIS (Netherlands)

    Grostal, P.; Dicke, M.

    2000-01-01

    Little has been done to compare the relative importance of various mechanisms through which prey assess the potential risk from natural enemies. We used predator-naive spider mites (Tetranychus urticae, Tetranychidae) to (1) compare the responses of prey to chemical cues from enemy and non-enemy

  17. The diet of otters ( Lutra lutra L.) in Danish freshwater habitats : comparisons of prey fish populations

    DEFF Research Database (Denmark)

    Taastrom, H.M.; Jacobsen, Lene

    1999-01-01

    Otter spraints from five Danish freshwater localities were analysed. In all localities fish was the main prey (76-99% of estimated bulk), especially in winter. Depending on locality, the prey fish mainly consisted of cyprinids (Cyprinidae), percids (Percidae) or salmonids (Salmonidae). Seasonal v...

  18. What you need is what you eat? Prey selection by the bat Myotis daubentonii

    NARCIS (Netherlands)

    Vesterinen, Eero; Ruokolainen, Lasse; Wahlberg, Niklas; Pena, Carlos; Roslin, Tomas; Laine, V.; Vasko, Ville; Sääksjärvi, Ilari; Norrdahl, Kai; Lilley, Thomas

    2016-01-01

    Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod

  19. Effects of an infectious fungus, Batrachochytrium dendrobatidis, on amphibian predator-prey interactions.

    Directory of Open Access Journals (Sweden)

    Barbara A Han

    2011-02-01

    Full Text Available The effects of parasites and pathogens on host behaviors may be particularly important in predator-prey contexts, since few animal behaviors are more crucial for ensuring immediate survival than the avoidance of lethal predators in nature. We examined the effects of an emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis, on anti-predator behaviors of tadpoles of four frog species. We also investigated whether amphibian predators consumed infected prey, and whether B. dendrobatidis caused differences in predation rates among prey in laboratory feeding trials. We found differences in anti-predator behaviors among larvae of four amphibian species, and show that infected tadpoles of one species (Anaxyrus boreas were more active and sought refuge more frequently when exposed to predator chemical cues. Salamander predators consumed infected and uninfected tadpoles of three other prey species at similar rates in feeding trials, and predation risk among prey was unaffected by B. dendrobatidis. Collectively, our results show that even sub-lethal exposure to B. dendrobatidis can alter fundamental anti-predator behaviors in some amphibian prey species, and suggest the unexplored possibility that indiscriminate predation between infected and uninfected prey (i.e., non-selective predation could increase the prevalence of this widely distributed pathogen in amphibian populations. Because one of the most prominent types of predators in many amphibian systems is salamanders, and because salamanders are susceptible to B. dendrobatidis, our work suggests the importance of considering host susceptibility and behavioral changes that could arise from infection in both predators and prey.

  20. Estimation of feeding patterns for piscivorous fish using individual prey data from stomach contents

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Temming, Axel

    2011-01-01

    The problem of estimating temporal feeding patterns using stomach data is considered, where the time of ingestion for each prey item can be predicted through a gastric evacuation model. The arrival of prey is modelled as a nonhomogeneous Poisson process with known periodic intensity. A maximum...

  1. Encounter success of free-ranging marine predator movements across a dynamic prey landscape.

    Science.gov (United States)

    Sims, David W; Witt, Matthew J; Richardson, Anthony J; Southall, Emily J; Metcalfe, Julian D

    2006-05-22

    Movements of wide-ranging top predators can now be studied effectively using satellite and archival telemetry. However, the motivations underlying movements remain difficult to determine because trajectories are seldom related to key biological gradients, such as changing prey distributions. Here, we use a dynamic prey landscape of zooplankton biomass in the north-east Atlantic Ocean to examine active habitat selection in the plankton-feeding basking shark Cetorhinus maximus. The relative success of shark searches across this landscape was examined by comparing prey biomass encountered by sharks with encounters by random-walk simulations of 'model' sharks. Movements of transmitter-tagged sharks monitored for 964 days (16754 km estimated minimum distance) were concentrated on the European continental shelf in areas characterized by high seasonal productivity and complex prey distributions. We show movements by adult and sub-adult sharks yielded consistently higher prey encounter rates than 90% of random-walk simulations. Behavioural patterns were consistent with basking sharks using search tactics structured across multiple scales to exploit the richest prey areas available in preferred habitats. Simple behavioural rules based on learned responses to previously encountered prey distributions may explain the high performances. This study highlights how dynamic prey landscapes enable active habitat selection in large predators to be investigated from a trophic perspective, an approach that may inform conservation by identifying critical habitat of vulnerable species.

  2. Are We Really the Prey? Nanotechnology as Science and Science Fiction

    Science.gov (United States)

    Bowman, Diana M.; Hodge, Graeme A.; Binks, Peter

    2007-01-01

    Popular culture can play a significant role in shaping the acceptance of evolving technologies, with nanotechnology likely to be a case in point. The most popular fiction work to date in this arena has been Michael Crichton's techno-thriller "Prey," which fuses together nanotechnology science with science fiction. Within the context of "Prey,"…

  3. Demographic consequences of predators on prey: trait and density mediated effects on mosquito larvae in containers.

    Directory of Open Access Journals (Sweden)

    Barry W Alto

    Full Text Available Predators may affect prey population growth and community diversity through density mediated lethal and trait mediated non-lethal effects that influence phenotypic traits of prey. We tested experimentally the roles of thinning the density of prey (lethality in the absence of predator cues and density and trait mediated effects (lethality + intimidation of predatory midge Corethrella appendiculata on competing native and invasive mosquito prey. Predator-mediated reductions in prey and density reductions in the absence of C. appendiculata resulted in lower percent survivorship to adulthood and estimates of the finite rate of increase (λ' for invasive mosquito Aedes albopictus relative to that of controls. In most instances, thinning the density of prey in the absence, but not in the presence, of C. appendiculata cues resulted in lower survivorship to adulthood and λ' for native mosquito Aedes triseriatus relative to that of controls. Together, these results suggested trait mediated effects of C. appendiculata specific to each species of mosquito prey. Release from intraspecific competition attributable to density reductions in the absence, but not in the presence, of C. appendiculata enhanced growth and lengthened adult lifespan relative to that of controls for A. albopictus but not A. triseriatus. These results show the importance of predator-mediated density and trait mediated effects on phenotypic traits and populations of invasive and native mosquitoes. Species-specific differences in the phenotypic responses of prey may be due, in part, to longer evolutionary history of C. appendiculata with A. triseriatus than A. albopictus.

  4. Effective prey attraction in the rare Drosophyllum lusitanicum, a flypaper-trap carnivorous plant.

    Science.gov (United States)

    Bertol, Nils; Paniw, Maria; Ojeda, Fernando

    2015-05-01

    Carnivorous plants have unusually modified leaves to trap insects as an adaptation to low-nutrient environments. Disparate mechanisms have been suggested as luring traits to attract prey insects into their deadly leaves, ranging from very elaborate to none at all. Drosophyllum lusitanicum is a rare carnivorous plant with a common flypaper-trap mechanism. Here we tested whether Drosophyllum plants lure prey insects into their leaves or they act just as passive traps. We compared prey capture between live, potted plants and Drosophyllum-shaped artificial mimics coated with odorless glue. Since this species is insect-pollinated, we also explored the possible existence of a pollinator-prey conflict by quantifying the similarity between the pollination and prey guilds in a natural population. All experiments were done in southern Spain. The sticky leaves of Drosophyllum captured significantly more prey than mimics, particularly small dipterans. Prey attraction, likely exerted by scent or visual cues, seems to be unrelated to pollinator attraction by flowers, as inferred from the low similarity between pollinator and prey insect faunas found in this species. Our results illustrate the effectiveness of this carnivorous species at attracting insects to their flypaper-trap leaves. © 2015 Botanical Society of America, Inc.

  5. Generalist predator, cyclic voles and cavity nests: testing the alternative prey hypothesis.

    Science.gov (United States)

    Pöysä, Hannu; Jalava, Kaisa; Paasivaara, Antti

    2016-12-01

    The alternative prey hypothesis (APH) states that when the density of the main prey declines, generalist predators switch to alternative prey and vice versa, meaning that predation pressure on the alternative prey should be negatively correlated with the density of the main prey. We tested the APH in a system comprising one generalist predator (pine marten, Martes martes), cyclic main prey (microtine voles, Microtus agrestis and Myodes glareolus) and alternative prey (cavity nests of common goldeneye, Bucephala clangula); pine marten is an important predator of both voles and common goldeneye nests. Specifically, we studied whether annual predation rate of real common goldeneye nests and experimental nests is negatively associated with fluctuation in the density of voles in four study areas in southern Finland in 2000-2011. Both vole density and nest predation rate varied considerably between years in all study areas. However, we did not find support for the hypothesis that vole dynamics indirectly affects predation rate of cavity nests in the way predicted by the APH. On the contrary, the probability of predation increased with vole spring abundance for both real and experimental nests. Furthermore, a crash in vole abundance from previous autumn to spring did not increase the probability of predation of real nests, although it increased that of experimental nests. We suggest that learned predation by pine marten individuals, coupled with efficient search image for cavities, overrides possible indirect positive effects of high vole density on the alternative prey in our study system.

  6. BEHAVIOR AND PREY OF NESTING RED-SHOULDERED HAWKS IN SOUTHWESTERN OHIO

    Science.gov (United States)

    We used direct observations to quantify prey types, prey delivery rate, and adult and nestling behavior at nests of Red-shouldered Hawks (Buteo lineatus) in suburban southwestern Ohio. Twenty-one nests were observed for a total of 256 hr in 1997-2001. Small mammals made up the ...

  7. Assessing diet compositions of Lake Ontario predators using fatty acid profiles of prey fishes

    Science.gov (United States)

    Happell, Austin; Pattridge, Robert; Rinchard, Jacques; Walsh, Maureen

    2017-01-01

    Fatty acid profiles are used in food web studies to assess trophic interactions between predator and prey. The present study provides the first comprehensive fatty acid dataset for important prey and predator species in Lake Ontario. Three major prey fish (alewife, rainbow smelt, and round goby) were collected at three sites along the southern shore of Lake Ontario during the spring and fall of 2013, and predator species were collected in similar locations during the summer of 2013. Fatty acid compositions were compared among all prey species, all predator species, and information from both predator and prey was used to infer foraging differences among predators. Seasonal differences in fatty acids were found within each prey species studied. Differences among prey species were greater than any spatio-temporal differences detected within species. Fatty acids of predators revealed species-specific differences that matched known foraging habits. Chinook and Coho salmon, which are known to select alewife as their dominant prey item, had relatively little variation in fatty acid profiles. Conversely, brown trout, lake trout, yellow perch and esocids had highly variable fatty acid profiles and likely highly variable diet compositions. In general, our data suggested three dominant foraging patterns: 1) diet composed of nearly exclusively alewife for Chinook and Coho Salmon; 2) a mixed diet of alewife and round goby for brown and lake trout, and both rock and smallmouth bass; 3) a diet that is likely comprised of forage fishes other than those included in our study for northern pike and chain pickerel.

  8. Correlation between the seasonal distribution of harbour porpoises and their prey in the Sound, Baltic Sea

    DEFF Research Database (Denmark)

    Sveegaard, Signe; Andreasen, Heidi; Mouritsen, Kim N.

    2012-01-01

    herring and Atlantic cod were equally important during the low-density season. Prey availability and predictability are suggested as the main drivers for harbour porpoise distribution, and this could be caused by the formation of frontal zones in spring in the northern part of the Sound, leading to prey...

  9. Extinction in a generalized Lotka-Volterra predator-prey model

    Directory of Open Access Journals (Sweden)

    Azmy S. Ackleh

    2000-01-01

    Full Text Available In this paper we discuss the asymptotic behavior of a predator-prey model with distributed growth and mortality rates. We exhibit simple criteria on the parameters which guarantee that all subpopulations but one predator-prey pair are driven to extinction as t→∞. Finally, we present numerical simulations to illustrate the theoretical results.

  10. Digestion rates of prey eaten by intertidal sea anemones from the ...

    African Journals Online (AJOL)

    Digestion rates were determined for natural prey items offered to each of seven species of sea anemones found at Wooley's Pool in False Say and to the single species (Bunodactis reynaudl) recorded at Siouberg on the Atlantic coast of the south-western Cape, South Africa.This was done by examining prey items removed ...

  11. Flocking and feeding in the fiddler crab (UCA tangeri) : Prey availability as risk-taking behaviour

    NARCIS (Netherlands)

    Ens, B; KLAASSEN, M; ZWARTS, L

    1993-01-01

    For a full understanding of prey availability, it is necessary to study risk-taking behaviour of the prey. Fiddler crabs are ideally suited for such a study, as they have to leave their safe burrow to feed on the surface of the intertidal flats during low tide, thereby exposing themselves to avian

  12. Effect of location and season on the arthropod prey of Nycteris ...

    African Journals Online (AJOL)

    Analysis of culled arthropod prey parts collected from beneath four feeding perches was used to assess prey taken by Nycteris grandis from November 1987 to May 1988. The perches were located along the Zambezi River in Mana Pools National Park in Zimbabwe.With the exception of an occasional solifugid, N. grandis ...

  13. Arthropod prey of nestling red-cockaded woodpeckers in the upper coastal plain of South Carolina

    Science.gov (United States)

    James L. Hanula; Kathleen E. Franzreb

    1995-01-01

    Four nest cavities of the Red-cockaded Woodpecker (Picoides borealis) were monitored with automatic cameras to determine the prey selected to feed nestlings. Twelve adults were photographed making nearly 3000 nest visits. Prey in 28 arthropod taxa were recognizable in 65% of the photographic slides. Wood roaches in the genus (Parcoblutta...

  14. Influence of prey abundance and abiotic factors on the long-term ...

    African Journals Online (AJOL)

    ... the home-range distribution of spotted grunter. Spatial distribution of prey appears to be a dominant factor influencing home-range parameters of this species within an intermittently open estuary. Keywords: acoustic telemetry, East Kleinemonde Estuary, estuarine fish, movement behaviour, prey abundance, South Africa ...

  15. Senses & Sensibility: Predator-Prey Experiments Reveal How Fish Perceive & Respond to Threats

    Science.gov (United States)

    Jones, Jason; Holloway, Barbara; Ketcham, Elizabeth; Long, John

    2008-01-01

    The predator-prey relationship is one of the most recognizable and well-studied animal relationships. One of the more striking aspects of this relationship is the differential natural selection pressure placed on predators and their prey. This differential pressure results from differing costs of failure, the so-called life-dinner principle. If a…

  16. Birds exploit herbivore-induced plant volatiles to locate herbivorous prey

    NARCIS (Netherlands)

    Amo, L.; Jansen, J.J.; Dam, van N.M.; Dicke, M.; Visser, M.E.

    2013-01-01

    Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous

  17. Along Came a Spider: Using Live Arthropods in a Predator-Prey Activity

    Science.gov (United States)

    Richardson, Matthew L.; Hari, Janice

    2011-01-01

    We developed a predator-prey activity with eighth-grade students in which they used wolf spiders ("Lycosa carolinensis"), house crickets ("Acheta domestica"), and abiotic factors to address how (1) adaptations in predators and prey shape their interaction and (2) abiotic factors modify the interaction between predators and…

  18. Clock-Controlled Prey-Predator Dynamics : Temporal Segregation of Activities

    OpenAIRE

    Hiroaki, DAIDO; Department of Mathematical Sciences, Graduate School of Engineering, University of Osaka Prefecture

    2003-01-01

    A new type of mathematical model of prey-predator dynamics is proposed. This model takes into account the fact that the daily activities of animals are governed by their body clocks. On the basis of it, we investigate the conditions under which the prey and predator can segregate into diurnal and nocturnal habits on a timescale that is short compared to evolutionary timescales.

  19. Foraging efficiency of a predator flock for randomly moving prey: A simulation study

    Science.gov (United States)

    Lee, Sang-Hee; Kwon, Ohsung

    2016-03-01

    Flocking behavior of animals is highly advantageous for taking food resources. The degree of the advantage is related to the ability of flock members to detect their prey and the mobility of prey individuals. In this study, to explore the relation, we constructed a model to simulate a predator flock and its randomly moving prey. The predator members have the prey detection ability, which was characterized as sensing distance, R, and a sensing angle, θ. The mobility of the prey individuals was characterized as the maximum traveling distance of an iteration time step, L. The relative flock foraging efficiency, ɛ, was defined as ɛ = 1 - (Td/Tup). Tup and Td represent the spent time for the flock to eat all prey individuals and to uptake the last remaining 10% prey, respectively. Simulation results showed that ɛ increased, maximized, and decreased with the increase of R, regardless of L. As the number of prey, N, increased, the tendency of the increasing and decreasing was diluted. The result was briefly discussed in relation to the flock foraging behavior and the development of the model toward applications for real ecosystems.

  20. Seasonal and among-stream variation in predator encounter rates for fish prey

    Science.gov (United States)

    Bret C. Harvey; Rodney J. Nakamoto

    2013-01-01

    Recognition that predators have indirect effects on prey populations that may exceed their direct consumptive effects highlights the need for a better understanding of spatiotemporal variation in predator–prey interactions. We used photographic monitoring of tethered Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout O. clarkii to quantify predator encounter rates...

  1. Challenges to a molecular approach to prey identification in the Burmese python, Python molurus bivittatus

    Science.gov (United States)

    Falk, Bryan; Reed, Robert N.

    2015-01-01

    Molecular approaches to prey identification are increasingly useful in elucidating predator–prey relationships, and we aimed to investigate the feasibility of these methods to document the species identities of prey consumed by invasive Burmese pythons in Florida. We were particularly interested in the diet of young snakes, because visual identification of prey from this size class has proven difficult. We successfully extracted DNA from the gastrointestinal contents of 43 young pythons, as well as from several control samples, and attempted amplification of DNA mini-barcodes, a 130-bp region of COX1. Using a PNA clamp to exclude python DNA, we found that prey DNA was not present in sufficient quality for amplification of this locus in 86% of our samples. All samples from the GI tracts of young pythons contained only hair, and the six samples we were able to identify to species were hispid cotton rats. This suggests that young Burmese pythons prey predominantly on small mammals and that prey diversity among snakes of this size class is low. We discuss prolonged gastrointestinal transit times and extreme gastric breakdown as possible causes of DNA degradation that limit the success of a molecular approach to prey identification in Burmese pythons

  2. Putting prey and predator into the CO2 equation--qualitative and quantitative effects of ocean acidification on predator-prey interactions.

    Science.gov (United States)

    Ferrari, Maud C O; McCormick, Mark I; Munday, Philip L; Meekan, Mark G; Dixson, Danielle L; Lonnstedt, Öona; Chivers, Douglas P

    2011-11-01

    Little is known about the impact of ocean acidification on predator-prey dynamics. Herein, we examined the effect of carbon dioxide (CO(2)) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO(2). Mortality rate and predator selectivity were compared across CO(2) treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO(2) levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO(2). Our results demonstrate both quantitative and qualitative consumptive effects of CO(2) on small and larger damselfish recruits respectively, resulting from CO(2)-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems. © 2011 Blackwell Publishing Ltd/CNRS.

  3. Foraging behaviour and prey size spectra of larval herring Clupea harengus

    DEFF Research Database (Denmark)

    Munk, Peter

    1992-01-01

    size groups of larval herring Clupea harengus L. were studied when preying on 6 size groups of copepods. Larval swimming and attack behaviour changed with prey size and were related to the ratio between prey length and larval length. The effective search rate showed a maximum when prey length was about......, that the available biomass of food as a proportion of the predator biomass will not increase. In order to assess the uniformity of relative prey size spectra of herring larvae and their background in larval foraging behaviour, a set of experimental and field investigations has been carried out. In the experiments, 4...... in the biomass spectra of the environment is important to larval growth and survival....

  4. Influence of vegetation on the nocturnal foraging behaviors and vertebrate prey capture by endangered Burrowing Owls

    Directory of Open Access Journals (Sweden)

    Alan Marsh

    2014-06-01

    Full Text Available Restrictions in technology have limited past habitat selection studies for many species to the home-range level, as a finer-scale understanding was often not possible. Consequently, these studies may not identify the true mechanism driving habitat selection patterns, which may influence how such results are applied in conservation. We used GPS dataloggers with digital video recorders to identify foraging modes and locations in which endangered Burrowing Owls (Athene cunicularia captured prey. We measured the coarse and fine-scale characteristics of vegetation at locations in which owls searched for, versus where they caught, vertebrate prey. Most prey items were caught using hover-hunting. Burrowing Owls searched for, and caught, vertebrate prey in all cover types, but were more likely to kill prey in areas with sparse and less dense vegetative cover. Management strategies designed to increase Burrowing Owl foraging success in the Canadian prairies should try to ensure a mosaic of vegetation heights across cover types.

  5. Prey selection and feeding habits of the large carnivores in the Southern Kalahari

    Directory of Open Access Journals (Sweden)

    M. G. L Mills

    1984-12-01

    Full Text Available Prey selection and feeding habits of lions Panthera leo, spotted hyaenas Crocuta crocuta, cheetahs Acinonyx jubatus and leopards Panthera pardus are investigated. Lions kill mainly adult gemsbok Oryx gazella and blue wildebeest Connochaetes taurinus, tending to select older animals of both species and males in the case of gemsbok. Spotted hyaenas also prey mainly on gemsbok and wildebeest, but select for juveniles, particularly from gemsbok. Cheetahs prey heavily on springbok Antidorcas marsupialis lambs and then on adult males and older individuals. Leopards also prey relatively heavily on springbok, but appear to have a wider diet than cheetahs do. It is concluded that predators generally have a small impact on their prey populations in the southern Kalahari, although in the case of springbok they do appear to influence the structure of the population.

  6. Prey selection by the Barn Owl Tyto alba (Scopoli, 1769 in captivity

    Directory of Open Access Journals (Sweden)

    V. Vanitha

    2009-07-01

    Full Text Available We investigated prey selection of the Barn Owl Tyto alba under captive conditions where birds were allowed to choose among individuals of varying size from four field rodent species: Bandicota bengalensis, Millardia meltada, Tatera indica and Mus booduga. Owls showed little species preference and a tendency to favour the medium weight class in all prey species except M. booduga. Preference for body parts consumed varied according to prey size, ranging from the head alone in the large weight class to the entire body in the small weight class. Biochemical measurements showed that protein, carbohydrate and lipid levels were higher respectively in the brain, liver and muscles of all three species and weight classes studied. The preference for medium weight prey despite a lower nutrient content compared to large weight prey is attributed to a greater ease of capture.

  7. Predator-prey interactions as macro-scale drivers of species diversity in mammals

    DEFF Research Database (Denmark)

    Sandom, Christopher James; Sandel, Brody Steven; Dalby, Lars

    Background/Question/Methods Understanding the importance of predator-prey interactions for species diversity is a central theme in ecology, with fundamental consequences for predicting the responses of ecosystems to land use and climate change. We assessed the relative support for different...... mechanistic drivers of mammal species richness at macro-scales for two trophic levels: predators and prey. To disentangle biotic (i.e. functional predator-prey interactions) from abiotic (i.e. environmental) and bottom-up from top-down determinants we considered three hypotheses: 1) environmental factors...... that determine ecosystem productivity drive prey and predator richness (the productivity hypothesis, abiotic, bottom-up), 2) consumer richness is driven by resource diversity (the resource diversity hypothesis, biotic, bottom-up) and 3) consumers drive richness of their prey (the top-down hypothesis, biotic, top...

  8. Sperm whale predator-prey interactions involve chasing and buzzing, but no acoustic stunning

    DEFF Research Database (Denmark)

    Fais, Andrea; Johnson, M.; Wilson, Maria

    2016-01-01

    The sperm whale carries a hypertrophied nose that generates powerful clicks for long-range echolocation. However, it remains a conundrum how this bizarrely shaped apex predator catches its prey. Several hypotheses have been advanced to propose both active and passive means to acquire prey......, including acoustic debilitation of prey with very powerful clicks. Here we test these hypotheses by using sound and movement recording tags in a fine-scale study of buzz sequences to relate the acoustic behaviour of sperm whales with changes in acceleration in their head region during prey capture attempts....... We show that in the terminal buzz phase, sperm whales reduce inter-click intervals and estimated source levels by 1-2 orders of magnitude. As a result, received levels at the prey are more than an order of magnitude below levels required for debilitation, precluding acoustic stunning to facilitate...

  9. Mechanisms of radiation in a bat group from the genus Pipistrellus inferred by phylogeography, demography and population genetics

    Czech Academy of Sciences Publication Activity Database

    Hulva, P.; Fornůsková, Alena; Chudárková, A.; Evin, A.; Allegrini, B.; Benda, P.; Bryja, Josef

    2010-01-01

    Roč. 19, č. 24 (2010), s. 5417-5431 ISSN 0962-1083 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60930519 Keywords : hybrid speciation * introgression * Mediterranean * microsatellites * mitochondrial DNA * phylogeography * bats * radiation Subject RIV: EG - Zoology Impact factor: 6.457, year: 2010

  10. Tracking the decline of the once-common butterfly: delayed oviposition, demography and population genetics in the hermit Chazara briseis

    Czech Academy of Sciences Publication Activity Database

    Kadlec, T.; Vrba, P.; Kepka, P.; Schmitt, T.; Konvička, Martin

    2010-01-01

    Roč. 13, č. 2 (2010), s. 172-183 ISSN 1367-9430 R&D Projects: GA MŠk LC06073 Grant - others:GA MŽP(CZ) VaV/620/1/03; GA ČR(CZ) GD206/05/H012 Program:GD Institutional research plan: CEZ:AV0Z50070508 Keywords : allozyme electrophoresis * Lepidoptera * mark-recapture Subject RIV: EH - Ecology, Behaviour Impact factor: 2.906, year: 2010

  11. When hawks attack: animal-borne video studies of goshawk pursuit and prey-evasion strategies

    Science.gov (United States)

    Kane, Suzanne Amador; Fulton, Andrew H.; Rosenthal, Lee J.

    2015-01-01

    Video filmed by a camera mounted on the head of a Northern Goshawk (Accipiter gentilis) was used to study how the raptor used visual guidance to pursue prey and land on perches. A combination of novel image analysis methods and numerical simulations of mathematical pursuit models was used to determine the goshawk's pursuit strategy. The goshawk flew to intercept targets by fixing the prey at a constant visual angle, using classical pursuit for stationary prey, lures or perches, and usually using constant absolute target direction (CATD) for moving prey. Visual fixation was better maintained along the horizontal than vertical direction. In some cases, we observed oscillations in the visual fix on the prey, suggesting that the goshawk used finite-feedback steering. Video filmed from the ground gave similar results. In most cases, it showed goshawks intercepting prey using a trajectory consistent with CATD, then turning rapidly to attack by classical pursuit; in a few cases, it showed them using curving non-CATD trajectories. Analysis of the prey's evasive tactics indicated that only sharp sideways turns caused the goshawk to lose visual fixation on the prey, supporting a sensory basis for the surprising frequency and effectiveness of this tactic found by previous studies. The dynamics of the prey's looming image also suggested that the goshawk used a tau-based interception strategy. We interpret these results in the context of a concise review of pursuit–evasion in biology, and conjecture that some prey deimatic ‘startle’ displays may exploit tau-based interception. PMID:25609783

  12. How much is too much? Assessment of prey consumption by Magellanic penguins in Patagonian colonies.

    Directory of Open Access Journals (Sweden)

    Juan E Sala

    Full Text Available Penguins are major consumers in the southern oceans although quantification of this has been problematic. One suggestion proposes the use of points of inflection in diving profiles ('wiggles' for this, a method that has been validated for the estimation of prey consumption by Magellanic penguins (Spheniscus magellanicus by Simeone and Wilson (2003. Following them, we used wiggles from 31 depth logger-equipped Magellanic penguins foraging from four Patagonian colonies; Punta Norte (PN, Bahía Bustamente (BB, Puerto Deseado (PD and Puerto San Julián (PSJ, all located in Argentina between 42-49° S, to estimate the prey captured and calculate the catch per unit time (CPUT for birds foraging during the early chick-rearing period. Numbers of prey caught and CPUT were significantly different between colonies. Birds from PD caught the highest number of prey per foraging trip, with CPUT values of 68±19 prey per hour underwater (almost two times greater than for the three remaining colonies. We modeled consumption from these data and calculate that the world Magellanic penguin population consumes about 2 million tons of prey per year. Possible errors in this calculation are discussed. Despite this, the analysis of wiggles seems a powerful and simple tool to begin to quantify prey consumption by Magellanic penguins, allowing comparison between different breeding sites. The total number of wiggles and/or CPUT do not reflect, by themselves, the availability of food for each colony, as the number of prey consumed by foraging trip is strongly associated with the energy content and wet mass of each colony-specific 'prey type'. Individuals consuming more profitable prey could be optimizing the time spent underwater, thereby optimizing the energy expenditure associated with the dives.

  13. Effect of sublethal levels of ionizing radiation on a predator-prey interaction

    International Nuclear Information System (INIS)

    Chee, P.C.

    1976-01-01

    The predator-prey interaction studied was that between the largemouth bass (Micropterus salmoides) and the fathead minnow (Pimephales promelas) in an artificial test environment. Experiments were first conducted to determine the 50% lethal dose at 30 days of the minnow. Three different dose rates were used to test the effect of dose rate on the 50% lethal dose value. After the 50% lethal dose was determined the predator-prey interaction experiment was conducted using 30% of the 50% lethal dose as the highest radiation dose, this dose being considered the upper limit to sublethal radiation levels. A 4 x 4 Latin square design was chosen for the experiment, with four treatment levels (control plus three radiation levels) and four replicates. In each test 10 prey minnow were offered to one predator bass and the number of prey left after 14 days was the parameter of interest. A predator-prey interaction experiment using a single high level of radiation and two types of controls as conducted to ascertain the ability of the test environment to detect changes in the predator-prey interaction. The two types of controls were irradiated prey not exposed to predation and non-irradiated prey exposed to predation. An experiment was also conducted to test the correlation between the physical activity patterns of minnow and different doses of radiation. At a dose rate of 37.8 rad/min the 50% lethal dose at 30 days for minnow was found to be 2650 rad. It was found that dose rate had a strong influence on the 50% lethal dose. In the predator-prey interaction test it was found that the 14-day survival rate of prey was unaffected by sublethal levels of ionizing radiation. No significant correlation was detected between the physical activity patterns of minnow and radiation dose

  14. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants

    Science.gov (United States)

    Chin, Lijin; Chung, Arthur YC; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes. PMID:24481246

  15. Prey capture by the crab spider Misumena calycina (Araneae: Thomisidae).

    Science.gov (United States)

    Morse, Douglass H

    1979-01-01

    Crab spiders Misumena calycina (L.) in pasture rose Rosa carolina flowers regularly attacked bumble bees, smaller bees, and syrphid flies that visited these flowers. Attacks reached a maximum rate of over 20/h during mid morning, but only 1.6% of the most important prey item, bumble bees, were captured. The next most important food source, the most frequently taken item, syrphid flies Toxomerus marginatus (Say), were captured in 39% of the attempts. Since these flies have a biomass only 1/60th that of bumble bees, they comprised a much less important food source than did bumble bees. Spiders would obtain over 7% more food by specializing on bumble bees than by attacking all insect visitors, and as much as 20% more food at certain times of the day. However, they did not show a tendency to specialize at any time.

  16. Baleen whales and their prey in a coastal environment

    Science.gov (United States)

    Piatt, John F.; Methven, David A.; Burger, Alan E.; McLagan, Ruth L.; Mercer, Vicki; Creelman, Elizabeth

    1989-01-01

    Patterns of abundance of humpback (Megaptera novaeangliae), fin (Balaenoptera physalus), and minke (Balaenoptera acutorostrata) whales are described in relation to the abundance of their primary prey, capelin (Mallotus villosus), during 1982–1985 at Witless Bay, Newfoundland. The abundance ratio of the three whale species was 10:1:3.5, respectively. Abundance of all whale species was strongly correlated with abundance of capelin through each season and between years. Capelin abundance accounted for 63% of the variation in whale numbers in 1983 and 1984, while environmental parameters (e.g., water temperatures) accounted for little variance. The amount of capelin consumed by whales was small (< 2%) compared with the amount available. All three species overlapped temporally at Witless Bay, but spatial overlap was reduced as fins occurred primarily offshore, minkes primarily inshore, and humpbacks in bay habitats of intermediate depth.

  17. Born Knowing: Tentacled Snakes Innately Predict Future Prey Behavior

    Science.gov (United States)

    Catania, Kenneth C.

    2010-01-01

    Background Aquatic tentacled snakes (Erpeton tentaculatus) can take advantage of their prey's escape response by startling fish with their body before striking. The feint usually startles fish toward the snake's approaching jaws. But when fish are oriented at a right angle to the jaws, the C-start escape response translates fish parallel to the snake's head. To exploit this latter response, snakes must predict the future location of the fish. Adult snakes can make this prediction. Is it learned, or are tentacled snakes born able to predict future fish behavior? Methods and Findings Laboratory-born, naïve snakes were investigated as they struck at fish. Trials were recorded at 250 or 500 frames per second. To prevent learning, snakes were placed in a water container with a clear transparency sheet or glass bottom. The chamber was placed over a channel in a separate aquarium with fish below. Thus snakes could see and strike at fish, without contact. The snake's body feint elicited C-starts in the fish below the transparency sheet, allowing strike accuracy to be quantified in relationship to the C-starts. When fish were oriented at a right angle to the jaws, naïve snakes biased their strikes to the future location of the escaping fish's head, such that the snake's jaws and the fish's translating head usually converged. Several different types of predictive strikes were observed. Conclusions The results show that some predators have adapted their nervous systems to directly compensate for the future behavior of prey in a sensory realm that usually requires learning. Instead of behavior selected during their lifetime, newborn tentacled snakes exhibit behavior that has been selected on a different scale—over many generations. Counter adaptations in fish are not expected, as tentacled snakes are rare predators exploiting fish responses that are usually adaptive. PMID:20585384

  18. Ineffective crypsis in a crab spider: a prey community perspective.

    Science.gov (United States)

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2010-03-07

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator.

  19. Interactive effects of prey and weather on golden eagle reproduction

    Science.gov (United States)

    Steenhof, Karen; Kochert, Michael N.; McDonald, T.L.

    1997-01-01

    1. The reproduction of the golden eagle Aquila chrysaetos was studied in southwestern Idaho for 23 years, and the relationship between eagle reproduction and jackrabbit Lepus californicus abundance, weather factors, and their interactions, was modelled using general linear models. Backward elimination procedures were used to arrive at parsimonious models.2. The number of golden eagle pairs occupying nesting territories each year showed a significant decline through time that was unrelated to either annual rabbit abundance or winter severity. However, eagle hatching dates were significantly related to both winter severity and jackrabbit abundance. Eagles hatched earlier when jackrabbits were abundant, and they hatched later after severe winters.3. Jackrabbit abundance influenced the proportion of pairs that laid eggs, the proportion of pairs that were successful, mean brood size at fledging, and the number of young fledged per pair. Weather interacted with prey to influence eagle reproductive rates.4. Both jackrabbit abundance and winter severity were important in predicting the percentage of eagle pairs that laid eggs. Percentage laying was related positively to jackrabbit abundance and inversely related to winter severity.5. The variables most useful in predicting percentage of laying pairs successful were rabbit abundance and the number of extremely hot days during brood-rearing. The number of hot days and rabbit abundance were also significant in a model predicting eagle brood size at fledging. Both success and brood size were positively related to jackrabbit abundance and inversely related to the frequency of hot days in spring.6. Eagle reproduction was limited by rabbit abundance during approximately twothirds of the years studied. Weather influenced how severely eagle reproduction declined in those years.7. This study demonstrates that prey and weather can interact to limit a large raptor population's productivity. Smaller raptors could be affected more

  20. Demography of a population collapse: the Northern Idaho ground squirrel (Spermophilus brunneus brunneus)

    Science.gov (United States)

    Sherman, P.W.; Runge, M.C.

    2002-01-01

    We studied the demography of a population of Northern Idaho ground squirrels (Spermophilus brunneus brunneus) in Adams Co., Idaho. The population was completely censused yearly from 1987 to 1999, during which time it declined from 272 to 10 animals. The finite population growth rate, based on a Leslie matrix model of average life-history parameters, was only 0.72 (i.e., significantly conifers to encroach on inhabited meadows, shrinking them and closing dispersal routes. The proximate cause of the population's collapse was mortality of older breeding females, which reduced the mean age of breeders. Younger females had lower average pregnancy rates and litter sizes. To place our results in context we developed a new, general classification of anthropogenic population declines, based on whether they are caused by changes in the means of the life-history parameters (blatant disturbances), their variances (inappropriate variations), or the correlations among them (evolutionary traps). Many S. b. brunneus populations have disappeared in recent years, apparently due to blatant disturbances, especially loss of habitat and changes in food-plant composition, resulting in inadequate prehibernation nutrition and starvation overwinter. In addition, our study population may have been caught in an evolutionary trap, because the vegetational cues that could potentially enable the animals to adjust reproduction to the anticipated food supply no longer correlate with availability of fat-laden seeds.

  1. Demography-based adaptive network model reproduces the spatial organization of human linguistic groups

    Science.gov (United States)

    Capitán, José A.; Manrubia, Susanna

    2015-12-01

    The distribution of human linguistic groups presents a number of interesting and nontrivial patterns. The distributions of the number of speakers per language and the area each group covers follow log-normal distributions, while population and area fulfill an allometric relationship. The topology of networks of spatial contacts between different linguistic groups has been recently characterized, showing atypical properties of the degree distribution and clustering, among others. Human demography, spatial conflicts, and the construction of networks of contacts between linguistic groups are mutually dependent processes. Here we introduce an adaptive network model that takes all of them into account and successfully reproduces, using only four model parameters, not only those features of linguistic groups already described in the literature, but also correlations between demographic and topological properties uncovered in this work. Besides their relevance when modeling and understanding processes related to human biogeography, our adaptive network model admits a number of generalizations that broaden its scope and make it suitable to represent interactions between agents based on population dynamics and competition for space.

  2. Demography of a breeding population of whimbrel (Numenius phaeopus) near Churchill, Manitoba, Canada

    Science.gov (United States)

    Perz, Johanna

    I used a GIS raster layer of an area in the Churchill, Manitoba region to investigate the effect of breeding habitat on demography and density of Whimbrel from 2010 through 2013. Program MARK was used to quantify adult and daily nest survival. Apparent annual survival of 0.73 +/- 0.06 SE (95% CI = 0.60-0.83) did not significantly differ between sexes or habitats and was lower than expected based on longevity records and estimates for other large-bodied shorebirds. Nest success, corrected for exposure days, was highly variable, ranging from a low of 3% (95% CI = 0-12%) in 2011 to a high of 71% (95% CI = 54-83%) in 2013. The highest rate of nest survival occurred in the spring with the warmest mean temperature. I developed a generalized linear model (GLM) with a negative-binomial distribution from random plots that were surveyed for abundance to extrapolate a local breeding population size of 410 +/- 230 SE and density of 3.2 birds per square km +/- 1.8 SE. The result of my study suggests that other aspects of habitat not captured by the land cover categories may be more important to population dynamics.

  3. Understanding variation in human fertility: what can we learn from evolutionary demography?

    Science.gov (United States)

    Sear, Rebecca; Lawson, David W; Kaplan, Hillard; Shenk, Mary K

    2016-04-19

    Decades of research on human fertility has presented a clear picture of how fertility varies, including its dramatic decline over the last two centuries in most parts of the world. Why fertility varies, both between and within populations, is not nearly so well understood. Fertility is a complex phenomenon, partly physiologically and partly behaviourally determined, thus an interdisciplinary approach is required to understand it. Evolutionary demographers have focused on human fertility since the 1980s. The first wave of evolutionary demographic research made major theoretical and empirical advances, investigating variation in fertility primarily in terms of fitness maximization. Research focused particularly on variation within high-fertility populations and small-scale subsistence societies and also yielded a number of hypotheses for why fitness maximization seems to break down as fertility declines during the demographic transition. A second wave of evolutionary demography research on fertility is now underway, paying much more attention to the cultural and psychological mechanisms underpinning fertility. It is also engaging with the complex, multi-causal nature of fertility variation, and with understanding fertility in complex modern and transitioning societies. Here, we summarize the history of evolutionary demographic work on human fertility, describe the current state of the field, and suggest future directions. © 2016 The Author(s).

  4. Demography and dog-human relationships of the dog population in Zimbabwean communal lands.

    Science.gov (United States)

    Butler, J R; Bingham, J

    2000-10-14

    Dogs are Zimbabwe's primary vector for rabies, and the majority live in communal lands (traditional agropastoralist rural areas). In 1994, a household questionnaire survey was conducted to provide baseline data on the demography and dog-human relationships of the dogs in the communal lands. The survey showed that all the dogs were owned, and there was no evidence of a feral population. They were unrestricted and semi-dependent on people. The numbers of dogs per capita varied little in each communal land, resulting in higher dog densities in communal lands with higher human densities, and indicating that people were not intolerant of dogs at higher densities. The population turnover was rapid: the life expectancy of the dogs was 1.1 years, the mean age 2.0 years, and 71.8 per cent died in their first year. The population was heavily skewed towards juveniles, with 40.8 per cent aged less than 12 months. Despite the high juvenile mortality, the population was growing by 6.52 per cent per annum. It was estimated that in 1994 there were 1.36 million dogs in communal lands.

  5. Mismatch between birth date and vegetation phenology slows the demography of roe deer.

    Directory of Open Access Journals (Sweden)

    Floriane Plard

    2014-04-01

    Full Text Available Marked impacts of climate change on biodiversity have frequently been demonstrated, including temperature-related shifts in phenology and life-history traits. One potential major impact of climate change is the modification of synchronization between the phenology of different trophic levels. High phenotypic plasticity in laying date has allowed many bird species to track the increasingly early springs resulting from recent environmental change, but although changes in the timing of reproduction have been well studied in birds, these questions have only recently been addressed in mammals. To track peak resource availability, large herbivores like roe deer, with a widespread distribution across Europe, should also modify their life-history schedule in response to changes in vegetation phenology over time. In this study, we analysed the influence of climate change on the timing of roe deer births and the consequences for population demography and individual fitness. Our study provides a rare quantification of the demographic costs associated with the failure of a species to modify its phenology in response to a changing world. Given these fitness costs, the lack of response of roe deer birth dates to match the increasingly earlier onset of spring is in stark contrast with the marked phenotypic responses to climate change reported in many other mammals. We suggest that the lack of phenotypic plasticity in birth timing in roe deer is linked to its inability to track environmental cues of variation in resource availability for the timing of parturition.

  6. King penguin demography since the last glaciation inferred from genome-wide data.

    Science.gov (United States)

    Trucchi, Emiliano; Gratton, Paolo; Whittington, Jason D; Cristofari, Robin; Le Maho, Yvon; Stenseth, Nils Chr; Le Bohec, Céline

    2014-07-22

    How natural climate cycles, such as past glacial/interglacial patterns, have shaped species distributions at the high-latitude regions of the Southern Hemisphere is still largely unclear. Here, we show how the post-glacial warming following the Last Glacial Maximum (ca 18 000 years ago), allowed the (re)colonization of the fragmented sub-Antarctic habitat by an upper-level marine predator, the king penguin Aptenodytes patagonicus. Using restriction site-associated DNA sequencing and standard mitochondrial data, we tested the behaviour of subsets of anonymous nuclear loci in inferring past demography through coalescent-based and allele frequency spectrum analyses. Our results show that the king penguin population breeding on Crozet archipelago steeply increased in size, closely following the Holocene warming recorded in the Epica Dome C ice core. The following population growth can be explained by a threshold model in which the ecological requirements of this species (year-round ice-free habitat for breeding and access to a major source of food such as the Antarctic Polar Front) were met on Crozet soon after the Pleistocene/Holocene climatic transition. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  7. Mismatch Between Birth Date and Vegetation Phenology Slows the Demography of Roe Deer

    Science.gov (United States)

    Plard, Floriane; Gaillard, Jean-Michel; Coulson, Tim; Hewison, A. J. Mark; Delorme, Daniel; Warnant, Claude; Bonenfant, Christophe

    2014-01-01

    Marked impacts of climate change on biodiversity have frequently been demonstrated, including temperature-related shifts in phenology and life-history traits. One potential major impact of climate change is the modification of synchronization between the phenology of different trophic levels. High phenotypic plasticity in laying date has allowed many bird species to track the increasingly early springs resulting from recent environmental change, but although changes in the timing of reproduction have been well studied in birds, these questions have only recently been addressed in mammals. To track peak resource availability, large herbivores like roe deer, with a widespread distribution across Europe, should also modify their life-history schedule in response to changes in vegetation phenology over time. In this study, we analysed the influence of climate change on the timing of roe deer births and the consequences for population demography and individual fitness. Our study provides a rare quantification of the demographic costs associated with the failure of a species to modify its phenology in response to a changing world. Given these fitness costs, the lack of response of roe deer birth dates to match the increasingly earlier onset of spring is in stark contrast with the marked phenotypic responses to climate change reported in many other mammals. We suggest that the lack of phenotypic plasticity in birth timing in roe deer is linked to its inability to track environmental cues of variation in resource availability for the timing of parturition. PMID:24690936

  8. Application of demography to energy facility development projects. Working Paper No. 39

    International Nuclear Information System (INIS)

    Krannich, R.S.; Stanfield, G.G.

    1977-01-01

    The emergence of concern regarding socioeconomic consequences of large-scale development projects has resulted in a growing literature directed as estimating the types and levels of various impact dimensions which can be expected to result in human communities experiencing such development. Among these dimensions, a focus on population change has been prevalent. Accurate demographic predictions may be viewed as critical for the adequate comprehension of and preparation for impacts deriving from projects such as energy facility developments. Unfortunately, the state of the art in projecting demographic consequences of energy projects has been generally inadequate. Several of the more influential prior methods for estimating local demographic effects of developing energy facilities are critiqued, although their specific prediction figures are not summarized. The studies reviewed were found to be of dubious practical utility, probably due in part to the failure of basic demography to provide a base of support for applied demographic research. This report sets forth recommendations for the development of a theoretical perspective which would more adequately serve the needs of practitioners attempting to predict local demographic effects of energy facility development

  9. Climatic and biotic stochasticity: disparate causes of convergent demographies in rare, sympatric plants.

    Science.gov (United States)

    Fox, Laurel R

    2007-12-01

    Species with known demographies may be used as proxies, or approximate models, to predict vital rates and ecological properties of target species that either have not been studied or are species for which data may be difficult to obtain. These extrapolations assume that model and target species with similar properties respond in the same ways to the same ecological factors, that they have similar population dynamics, and that the similarity of vital rates reflects analogous responses to the same factors. I used two rare, sympatric annual plants (sand gilia [Gilia tenuiflora arenaria] and Monterey spineflower [Chorizanthe pungens pungens]) to test these assumptions experimentally. The vital rates of these species are similar and strongly correlated with rainfall, and I added water and/or prevented herbivore access to experimental plots. Their survival and reproduction were driven by different, largely stochastic factors and processes: sand gilia by herbivory and Monterey spineflower by rainfall. Because the causal agents and processes generating similar demographic patterns were species specific, these results demonstrate, both theoretically and empirically, that it is critical to identify the ecological processes generating observed effects and that experimental manipulations are usually needed to determine causal mechanisms. Without such evidence to identify mechanisms, extrapolations among species may lead to counterproductive management and conservation practices.

  10. The Role of Demography and Markets in Determining Deforestation Rates Near Ranomafana National Park, Madagascar

    Science.gov (United States)

    Brooks, Christopher P.; Holmes, Christopher; Kramer, Karen; Barnett, Barry; Keitt, Timothy H.

    2009-01-01

    The highland forests of Madagascar are home to some of the world's most unique and diverse flora and fauna and to some of its poorest people. This juxtaposition of poverty and biodiversity is continually reinforced by rapid population growth, which results in increasing pressure on the remaining forest habitat in the highland region, and the biodiversity therein. Here we derive a mathematical expression for the subsistence of households to assess the role of markets and household demography on deforestation near Ranomafana National Park. In villages closest to urban rice markets, households were likely to clear less land than our model predicted, presumably because they were purchasing food at market. This effect was offset by the large number of migrant households who cleared significantly more land between 1989–2003 than did residents throughout the region. Deforestation by migrant households typically occurred after a mean time lag of 9 years. Analyses suggest that while local conservation efforts in Madagascar have been successful at reducing the footprint of individual households, large-scale conservation must rely on policies that can reduce the establishment of new households in remaining forested areas. PMID:19536282

  11. Climate and demography in early prehistory: using calibrated (14)C dates as population proxies.

    Science.gov (United States)

    Riede, Felix

    2009-04-01

    Although difficult to estimate for prehistoric hunter-gatherer populations, demographic variables-population size, density, and the connectedness of demes-are critical for a better understanding of the processes of material culture change, especially in deep prehistory. Demography is the middle-range link between climatic changes and both biological and cultural evolutionary trajectories of human populations. Much of human material culture functions as a buffer against climatic changes, and the study of prehistoric population dynamics, estimated through changing frequencies of calibrated radiocarbon dates, therefore affords insights into how effectively such buffers operated and when they failed. In reviewing a number of case studies (Mesolithic Ireland, the origin of the Bromme culture, and the earliest late glacial human recolonization of southern Scandinavia), I suggest that a greater awareness of demographic processes, and in particular of demographic declines, provides many fresh insights into what structured the archaeological record. I argue that we cannot sideline climatic and environmental factors or extreme geophysical events in our reconstructions of prehistoric culture change. The implications of accepting demographic variability as a departure point for evaluating the archaeological record are discussed.

  12. The demography of the lizard Tropidurus torquatus (Squamata, Tropiduridae in a highly seasonal Neotropical savanna

    Directory of Open Access Journals (Sweden)

    Helga C. Wiederhecker

    2003-01-01

    Full Text Available The demography of a population of Tropidurus torquatus was studied from March 1996 until December 1998, in the Cerrado biome of the Central Brazil, using the method of capture and recapture. Population size, number of incoming individuals in the population, and age structure varied seasonally, reflecting the reproductive cycle of the species. The instantaneous rate of population increase did not differ from zero throughout the study. In general, the permanence rate of juveniles and adults were low, indicating a large turnover of individuals in the population, with a maximum life expectancy of three years. The sex-ratio among adults was biased toward females. Since no bias was observed among juveniles and there was no difference in adults permanence between sexes, we suggestet that the biased adult sex-ratio resulted from a lower permanence of males during a short ontogenetic period, when secondary sexual characteristics develop. When compared to T. itambere, the studied population of T. torquatus attained a higher density and a greater female bias in the sex-ratio. In general, the studied population presented characteristics that, according to life history theory, should be associated with early age at maturity and polyginy: short life expectancy, high population turnover, and female biased sex-ratios.

  13. Prey diversity is affected by climate and differs between age classes in the Red-backed Shrike (Lanius collurio)

    DEFF Research Database (Denmark)

    Pedersen, Lykke; Geertsma, Marten; Tøttrup, Anders P.

    2012-01-01

    -backed Shrike (Lanius collurio) populations in Denmark, based onmore than 11,000 prey items covering seven years.We found a negative correlation between prey diversity and temperature, indicating that Red-backed Shrikes feed on preferred prey items in warmer summers (low diversity)while forced to feed...

  14. The curse of the prey: Sarcoptes mite molecular analysis reveals potential prey-to-predator parasitic infestation in wild animals from Masai Mara, Kenya

    Directory of Open Access Journals (Sweden)

    Soriguer Ramón C

    2011-10-01

    Full Text Available Abstract Background Recently, there have been attempts to understand the molecular epidemiology of Sarcoptes scabiei, to evaluate the gene flow between isolates of S. scabiei from different hosts and geographic regions. However, to our knowledge, a molecular study has not been carried out to assess the molecular diversity and gene flow of Sarcoptes mite in a predator/prey ecosystem. Results Our study revealed an absence of gene flow between the two herbivore (Thomson's gazelle and wildebeest- and between the two carnivore (lion and cheetah-derived Sarcoptes populations from Masai Mara (Kenya, which is in discrepancy with the host-taxon law described for wild animals in Europe. Lion- and wildebeest-derived Sarcoptes mite populations were similar yet different from the Thomson's gazelle-derived Sarcoptes population. This could be attributed to Sarcoptes cross-infestation from wildebeest ("favourite prey" of the lion, but not from Thomson's gazelle. The cheetah-derived Sarcoptes population had different subpopulations: one is cheetah-private, one similar to the wildebeest- and lion-derived Sarcoptes populations, and another similar to the Thomson's gazelle-derived Sarcoptes mite population, where both wildebeest and Thomson's gazelle are "favourite preys" for the cheetah. Conclusions In a predator/prey ecosystem, like Masai Mara in Kenya, it seems that Sarcoptes infestation in wild animals is prey-to-predator-wise, depending on the predator's "favourite prey". More studies on the lion and cheetah diet and behaviour could be of great help to clarify the addressed hypotheses. This study could have further ramification in the epidemiological studies and the monitoring protocols of the neglected Sarcoptes mite in predator/prey ecosystems.

  15. Prey life-history and bioenergetic responses across a predation gradient.

    Science.gov (United States)

    Rennie, M D; Purchase, C F; Shuter, B J; Collins, N C; Abrams, P A; Morgan, G E

    2010-10-01

    To evaluate the importance of non-consumptive effects of predators on prey life histories under natural conditions, an index of predator abundance was developed for naturally occurring populations of a common prey fish, the yellow perch Perca flavescens, and compared to life-history variables and rates of prey energy acquisition and allocation as estimated from mass balance models. The predation index was positively related to maximum size and size at maturity in both male and female P. flavescens, but not with life span or reproductive investment. The predation index was positively related to size-adjusted specific growth rates and growth efficiencies but negatively related to model estimates of size-adjusted specific consumption and activity rates in both vulnerable (small) and invulnerable (large) size classes of P. flavescens. These observations suggest a trade-off between growth and activity rates, mediated by reduced activity in response to increasing predator densities. Lower growth rates and growth efficiencies in populations with fewer predators, despite increased consumption suggests either 1) a reduction in prey resources at lower predator densities or 2) an intrinsic cost of rapid prey growth that makes it unfavourable unless offset by a perceived threat of predation. This study provides evidence of trade-offs between growth and activity rates induced by predation risk in natural prey fish populations and illustrates how behavioural modification induced through predation can shape the life histories of prey fish species. © 2010 The Authors. Journal compilation © 2010 The Fisheries Society of the British Isles.

  16. Infrared tomographic PIV and 3D motion tracking system applied to aquatic predator–prey interaction

    International Nuclear Information System (INIS)

    Adhikari, Deepak; Longmire, Ellen K

    2013-01-01

    Infrared tomographic PIV and 3D motion tracking are combined to measure evolving volumetric velocity fields and organism trajectories during aquatic predator–prey interactions. The technique was used to study zebrafish foraging on both non-evasive and evasive prey species. Measurement volumes of 22.5 mm × 10.5 mm × 12 mm were reconstructed from images captured on a set of four high-speed cameras. To obtain accurate fluid velocity vectors within each volume, fish were first masked out using an automated visual hull method. Fish and prey locations were identified independently from the same image sets and tracked separately within the measurement volume. Experiments demonstrated that fish were not influenced by the infrared laser illumination or the tracer particles. Results showed that the zebrafish used different strategies, suction and ram feeding, for successful capture of non-evasive and evasive prey, respectively. The two strategies yielded different variations in fluid velocity between the fish mouth and the prey. In general, the results suggest that the local flow field, the direction of prey locomotion with respect to the predator and the relative accelerations and speeds of the predator and prey may all be significant in determining predation success. (paper)

  17. The predatory mite Phytoseiulus persimilis adjusts patch-leaving to own and progeny prey needs.

    Science.gov (United States)

    Vanas, V; Enigl, M; Walzer, A; Schausberger, P

    2006-01-01

    Integration of optimal foraging and optimal oviposition theories suggests that predator females should adjust patch leaving to own and progeny prey needs to maximize current and future reproductive success. We tested this hypothesis in the predatory mite Phytoseiulus persimilis and its patchily distributed prey, the two-spotted spider mite Tetranychus urticae. In three separate experiments we assessed (1) the minimum number of prey needed to complete juvenile development, (2) the minimum number of prey needed to produce an egg, and (3) the ratio between eggs laid and spider mites left when a gravid P. persimilis female leaves a patch. Experiments (1) and (2) were the pre-requirements to assess the fitness costs associated with staying or leaving a prey patch. Immature P. persimilis needed at least 7 and on average 14+/-3.6 (SD) T. urticae eggs to reach adulthood. Gravid females needed at least 5 and on average 8.5+/-3.1 (SD) T. urticae eggs to produce an egg. Most females left the initial patch before spider mite extinction, leaving prey for progeny to develop to adulthood. Females placed in a low density patch left 5.6+/-6.1 (SD) eggs per egg laid, whereas those placed in a high density patch left 15.8+/-13.7 (SD) eggs per egg laid. The three experiments in concert suggest that gravid P. persimilis females are able to balance the trade off between optimal foraging and optimal oviposition and adjust patch-leaving to own and progeny prey needs.

  18. Plant architecture and prey distribution influence foraging behavior of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae).

    Science.gov (United States)

    Gontijo, Lessando M; Nechols, James R; Margolies, David C; Cloyd, Raymond A

    2012-01-01

    The arrangement, number, and size of plant parts may influence predator foraging behavior, either directly, by altering the rate or pattern of predator movement, or, indirectly, by affecting the distribution and abundance of prey. We report on the effects of both plant architecture and prey distribution on foraging by the predatory mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), on cucumber (Cucumis sativus L.). Plants differed in leaf number (2- or 6-leafed), and there were associated differences in leaf size, plant height, and relative proportions of plant parts; but all had the same total surface area. The prey, the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), were distributed either on the basal leaf or on all leaves. The effect of plant architecture on predator foraging behavior varied depending on prey distribution. The dimensions of individual plant parts affected time allocated to moving and feeding, but they did not appear to influence the frequency with which predators moved among different plant parts. Overall, P. persimilis moved less, and fed upon prey longer, on 6-leafed plants with prey on all leaves than on plants representing other treatment combinations. Our findings suggest that both plant architecture and pattern of prey distribution should be considered, along with other factors such as herbivore-induced plant volatiles, in augmentative biological control programs.

  19. Adaptive evolution of defense ability leads to diversification of prey species.

    Science.gov (United States)

    Zu, Jian; Wang, Jinliang; Du, Jianqiang

    2014-06-01

    In this paper, by using the adaptive dynamics approach, we investigate how the adaptive evolution of defense ability promotes the diversity of prey species in an initial one-prey-two-predator community. We assume that the prey species can evolve to a safer strategy such that it can reduce the predation risk, but a prey with a high defense ability for one predator may have a low defense ability for the other and vice versa. First, by using the method of critical function analysis, we find that if the trade-off is convex in the vicinity of the evolutionarily singular strategy, then this singular strategy is a continuously stable strategy. However, if the trade-off is weakly concave near the singular strategy and the competition between the two predators is relatively weak, then the singular strategy may be an evolutionary branching point. Second, we find that after the branching has occurred in the prey strategy, if the trade-off curve is globally concave, then the prey species might eventually evolve into two specialists, each caught by only one predator species. However, if the trade-off curve is convex-concave-convex, the prey species might eventually branch into two partial specialists, each being caught by both of the two predators and they can stably coexist on the much longer evolutionary timescale.

  20. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey

    Science.gov (United States)

    Wilson, John W.; Mills, Michael G. L.; Wilson, Rory P.; Peters, Gerrit; Mills, Margaret E. J.; Speakman, John R.; Durant, Sarah M.; Bennett, Nigel C.; Marks, Nikki J.; Scantlebury, Michael

    2013-01-01

    Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s−1 and accelerated up to 7.5 m s−2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival. PMID:24004493

  1. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana

    Science.gov (United States)

    Winterbach, Christiaan W.; Boast, Lorraine K.; Klein, Rebecca; Somers, Michael J.

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs’ preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana’s agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana’s still large and contiguous cheetah population. PMID:26213646

  2. Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats

    Science.gov (United States)

    Luo, Jinhong; Koselj, Klemen; Zsebők, Sándor; Siemers, Björn M.; Goerlitz, Holger R.

    2014-01-01

    Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey. PMID:24335559

  3. Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats.

    Science.gov (United States)

    Luo, Jinhong; Koselj, Klemen; Zsebok, Sándor; Siemers, Björn M; Goerlitz, Holger R

    2014-02-06

    Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey.

  4. Musculoskeletal anatomy of the Eurasian lynx, Lynx lynx (Carnivora: Felidae) forelimb: Adaptations to capture large prey?

    Science.gov (United States)

    Viranta, Suvi; Lommi, Hanna; Holmala, Katja; Laakkonen, Juha

    2016-06-01

    Mammalian carnivores adhere to two different feeding strategies relative to their body masses. Large carnivores prey on animals that are the same size or larger than themselves, whereas small carnivores prey on smaller vertebrates and invertebrates. The Eurasian lynx (Lynx lynx) falls in between these two categories. Lynx descend from larger forms that were probably large prey specialists, but during the Pleistocene became predators of small prey. The modern Eurasian lynx may be an evolutionary reversal toward specializing in large prey again. We hypothesized that the musculoskeletal anatomy of lynx should show traits for catching large prey. To test our hypothesis, we dissected the forelimb muscles of six Eurasian lynx individuals and compared our findings to results published for other felids. We measured the bones and compared their dimensions to the published material. Our material displayed a well-developed pectoral girdle musculature with some uniquely extensive muscle attachments. The upper arm musculature resembled that of the pantherine felids and probably the extinct sabertooths, and also the muscles responsible for supination and pronation were similar to those in large cats. The muscles controlling the pollex were well-developed. However, skeletal indices were similar to those of small prey predators. Our findings show that lynx possess the topographic pattern of muscle origin and insertion like in large felids. J. Morphol. 277:753-765, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef.

    Science.gov (United States)

    Hackerott, Serena; Valdivia, Abel; Cox, Courtney E; Silbiger, Nyssa J; Bruno, John F

    2017-01-01

    Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0-10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

  6. Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef

    Directory of Open Access Journals (Sweden)

    Serena Hackerott

    2017-05-01

    Full Text Available Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0–10 cm total length at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

  7. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana.

    Science.gov (United States)

    Winterbach, Hanlie E K; Winterbach, Christiaan W; Boast, Lorraine K; Klein, Rebecca; Somers, Michael J

    2015-01-01

    Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus), additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs' preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana's agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana's still large and contiguous cheetah population.

  8. Relative availability of natural prey versus livestock predicts landscape suitability for cheetahs Acinonyx jubatus in Botswana

    Directory of Open Access Journals (Sweden)

    Hanlie E.K. Winterbach

    2015-07-01

    Full Text Available Prey availability and human-carnivore conflict are strong determinants that govern the spatial distribution and abundance of large carnivore species and determine the suitability of areas for their conservation. For wide-ranging large carnivores such as cheetahs (Acinonyx jubatus, additional conservation areas beyond protected area boundaries are crucial to effectively conserve them both inside and outside protected areas. Although cheetahs prefer preying on wild prey, they also cause conflict with people by predating on especially small livestock. We investigated whether the distribution of cheetahs’ preferred prey and small livestock biomass could be used to explore the potential suitability of agricultural areas in Botswana for the long-term persistence of its cheetah population. We found it gave a good point of departure for identifying priority areas for land management, the threat to connectivity between cheetah populations, and areas where the reduction and mitigation of human-cheetah conflict is critical. Our analysis showed the existence of a wide prey base for cheetahs across large parts of Botswana’s agricultural areas, which provide additional large areas with high conservation potential. Twenty percent of wild prey biomass appears to be the critical point to distinguish between high and low probable levels of human-cheetah conflict. We identified focal areas in the agricultural zones where restoring wild prey numbers in concurrence with effective human-cheetah conflict mitigation efforts are the most immediate conservation strategies needed to maintain Botswana’s still large and contiguous cheetah population.

  9. Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey.

    Science.gov (United States)

    Wilson, John W; Mills, Michael G L; Wilson, Rory P; Peters, Gerrit; Mills, Margaret E J; Speakman, John R; Durant, Sarah M; Bennett, Nigel C; Marks, Nikki J; Scantlebury, Michael

    2013-10-23

    Predator-prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s(-1) and accelerated up to 7.5 m s(-2) with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5-8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.

  10. Post-attack aposematic display in prey facilitates predator avoidance learning

    Directory of Open Access Journals (Sweden)

    Changku eKang

    2016-04-01

    Full Text Available Warning signals protect unpalatable prey from predation because predators who learn the association between the warning signal and prey unprofitability decrease attacks on the prey. Most of the research have focused on visual aposematic signals that are constantly presented and visible to the predators. But a variety of chemically defended insects are rather cryptic when resting, and only in response to predator attacks (post-attack they perform displays of conspicuous abdomens or hindwings normally hidden under forewings. The function of those displays in unpalatable insects is not well understood. We examined two adaptive hypotheses on this facultative aposematic display using wild-caught oriental tits (Parus minor as predators. First, we tested whether the display increases the rejection of the prey by predators upon seeing the display (i.e. at the moment of attack through learning trials (aposematic signaling hypothesis. Second, we tested whether the display facilitates the memory formation between cryptic visible form of the prey and prey defense so that it prevents the predators initiate an attack upon seeing the cryptic form (facilitation hypothesis. We found that predators learned to avoid attacking the prey which supports the facilitation hypothesis. However, the support for the aposematic signaling hypothesis was equivocal. Our results open new directions of research by highlighting the possibility that similar facilitation effects may contribute to the evolution of various forms of post-attack visual displays in chemically, or otherwise, defended animals.

  11. Impact of marine reserve on maximum sustainable yield in a traditional prey-predator system

    Science.gov (United States)

    Paul, Prosenjit; Kar, T. K.; Ghorai, Abhijit

    2018-01-01

    Multispecies fisheries management requires managers to consider the impact of fishing activities on several species as fishing impacts both targeted and non-targeted species directly or indirectly in several ways. The intended goal of traditional fisheries management is to achieve maximum sustainable yield (MSY) from the targeted species, which on many occasions affect the targeted species as well as the entire ecosystem. Marine reserves are often acclaimed as the marine ecosystem management tool. Few attempts have been made to generalize the ecological effects of marine reserve on MSY policy. We examine here how MSY and population level in a prey-predator system are affected by the low, medium and high reserve size under different possible scenarios. Our simulation works shows that low reserve area, the value of MSY for prey exploitation is maximum when both prey and predator species have fast movement rate. For medium reserve size, our analysis revealed that the maximum value of MSY for prey exploitation is obtained when prey population has fast movement rate and predator population has slow movement rate. For high reserve area, the maximum value of MSY for prey's exploitation is very low compared to the maximum value of MSY for prey's exploitation in case of low and medium reserve. On the other hand, for low and medium reserve area, MSY for predator exploitation is maximum when both the species have fast movement rate.

  12. Modulation of shark prey capture kinematics in response to sensory deprivation.

    Science.gov (United States)

    Gardiner, Jayne M; Atema, Jelle; Hueter, Robert E; Motta, Philip J

    2017-02-01

    The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark. Sharks were examined intact and after sensory information was blocked (olfaction, vision, mechanoreception, and electroreception, alone and in combination), to elucidate the contribution of the senses to the kinematics of prey capture. In response to sensory deprivation, the blacktip shark demonstrated the greatest amount of modulation, followed by the nurse shark. In the absence of olfaction, blacktip sharks open the jaws slowly, suggestive of less motivation. Without lateral line cues, blacktip sharks capture prey from greater horizontal angles using increased ram. When visual cues are absent, blacktip sharks elevate the head earlier and to a greater degree, allowing them to overcome imprecise position of the prey relative to the mouth, and capture prey using decreased ram, while suction remains unchanged. When visual cues are absent, nurse sharks open the mouth wider, extend the labial cartilages further, and increase suction while simultaneously decreasing ram. Unlike some bony fish, neither species switches feeding modalities (i.e. from ram to suction or vice versa). Bonnetheads failed to open the mouth when electrosensory cues were blocked, but otherwise little to no modulation was found in this species. These results suggest that prey capture may be less plastic in elasmobranchs than in bony fishes, possibly due to anatomical differences, and that the ability to modulate feeding kinematics in response to available sensory information varies

  13. Inferring predator behavior from attack rates on prey-replicas that differ in conspicuousness.

    Directory of Open Access Journals (Sweden)

    Yoel E Stuart

    Full Text Available Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator's ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators' direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined.

  14. Food abundance, prey morphology, and diet specialization influence individual sea otter tool use

    Science.gov (United States)

    Fujii, Jessica A.; Ralls, Katherine; Tinker, M. Tim

    2017-01-01

    Sea otters are well-known tool users, employing objects such as rocks or shells to break open invertebrate prey. We used a series of generalized linear mixed effect models to examine observational data on prey capture and tool use from 211 tagged individuals from 5 geographically defined study areas throughout the sea otter’s range in California. Our best supported model was able to explain 75% of the variation in the frequency of tool use by individual sea otters with only ecological and demographic variables. In one study area, where sea otter food resources were abundant, all individuals had similar diets focusing on preferred prey items and used tools at low to moderate frequencies (4–38% of prey captures). In the remaining areas, where sea otters were food-limited, individuals specialized on different subsets of the available prey and had a wider range of average tool-use frequency (0–98% of prey captures). The prevalence of difficult-to-access prey in individual diets was a major predictor of tool use and increased the likelihood of using tools on prey that were not difficult to access as well. Age, sex, and feeding habitat also contributed to the probability of tool use but to a smaller extent. We developed a conceptual model illustrating how food abundance, the prevalence of difficult-to-access prey, and individual diet specialization interacted to determine the likelihood that individual sea otters would use tools and considered the model’s relevance to other tool-using species.

  15. Modelling the dynamics of traits involved in fighting-predators-prey system.

    Science.gov (United States)

    Kooi, B W

    2015-12-01

    We study the dynamics of a predator-prey system where predators fight for captured prey besides searching for and handling (and digestion) of the prey. Fighting for prey is modelled by a continuous time hawk-dove game dynamics where the gain depends on the amount of disputed prey while the costs for fighting is constant per fighting event. The strategy of the predator-population is quantified by a trait being the proportion of the number of predator-individuals playing hawk tactics. The dynamics of the trait is described by two models of adaptation: the replicator dynamics (RD) and the adaptive dynamics (AD). In the RD-approach a variant individual with an adapted trait value changes the population's strategy, and consequently its trait value, only when its payoff is larger than the population average. In the AD-approach successful replacement of the resident population after invasion of a rare variant population with an adapted trait value is a step in a sequence changing the population's strategy, and hence its trait value. The main aim is to compare the consequences of the two adaptation models. In an equilibrium predator-prey system this will lead to convergence to a neutral singular strategy, while in the oscillatory system to a continuous singular strategy where in this endpoint the resident population is not invasible by any variant population. In equilibrium (low prey carrying capacity) RD and AD-approach give the same results, however not always in a periodically oscillating system (high prey carrying-capacity) where the trait is density-dependent. For low costs the predator population is monomorphic (only hawks) while for high costs dimorphic (hawks and doves). These results illustrate that intra-specific trait dynamics matters in predator-prey dynamics.

  16. Relative Preference and Localized Food Affect Predator Space Use and Consumption of Incidental Prey.

    Directory of Open Access Journals (Sweden)

    Tyler E Schartel

    Full Text Available Abundant, localized foods can concentrate predators and their foraging efforts, thus altering both the spatial distribution of predation risk and predator preferences for prey that are encountered incidentally. However, few investigations have quantified the spatial scale over which localized foods affect predator foraging behavior and consumption of incidental prey. In spring 2010, we experimentally tested how point-source foods altered how generalist predators (white-footed mice, Peromyscus leucopus utilized space and depredated two incidental prey items: almonds (Prunus dulcis; highly profitable and maple seeds (Acer saccharum; less profitable. We estimated mouse population densities with trapping webs, quantified mouse consumption rates of these incidental prey items, and measured local mouse activity with track plates. We predicted that 1 mouse activity would be elevated near full feeders, but depressed at intermediate distances from the feeder, 2 consumption of both incidental prey would be high near feeders providing less-preferred food and, 3 consumption of incidental prey would be contingent on predator preference for prey relative to feeders providing more-preferred food. Mouse densities increased significantly from pre- to post-experiment. Mean mouse activity was unexpectedly greatest in control treatments, particularly <15 m from the control (empty feeder. Feeders with highly preferred food (sunflower seeds created localized refuges for incidental prey at intermediate distances (15 to 25m from the feeder. Feeders with less-preferred food (corn generated localized high risk for highly preferred almonds <10 m of the feeder. Our findings highlight the contingent but predictable effects of locally abundant food on risk experienced by incidental prey, which can be positive or negative depending on both spatial proximity and relative preference.

  17. Predator-prey interactions in selected slow and fast developing females of a ladybird, Propylea dissecta.

    Science.gov (United States)

    Siddiqui, Arshi; Omkar; Mishra, Geetanjali

    2015-10-14

    Development rate polymorphism describes the scenario in which individuals exhibit distinct differences in their rate of development resulting in slow and fast developers even from the same clutch of eggs. Previously we showed that in ladybird, Propylea dissecta fast developers have higher foraging and predation rates than slow developers. But correlation between foraging efficacies with reproductive output of female remains unexplored. We selected slow and fast developmental rate for 15 generations in a P. dissecta and assessed female functional response and numerical response by using varying prey biomasses (A. pisum). We evaluated predatory parameters: prey consumption, attack rate, handling time, and the reproductive measures: number of eggs laid, egg, and body biomass conversion efficiencies. Overall, both group of P. dissecta showed increased prey biomasses curvilinear for consumption rate demonstrating the physiological capacity of foraging for food are mutually exclusive behaviors (i.e., Holling's Type-II functional response). Consumption rate and proportion of prey consumed was higher, and prey handling time was shorter, in experimental fast developers. However, prey attack rate was higher in experimental slow developers. The functional response of experimental fast developers got elevated whereas got depressed for control slow-fast developers. Our results suggest that slow developers may perform better at low prey biomass than fast developers due to their high attack rate whereas high density prey may favour fast developers due to their shorter prey handling time and higher consumption rates. This study is first attempt to evaluate predatory responses of experimentally selected lines of slow and fast developers. J. Exp. Zool. 9999A:XX-XX, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  18. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    International Nuclear Information System (INIS)

    Navalpotro, H.; Pagani-Nuñez, E.; Hernandez-Gomez, S.; Senar, J.C.

    2016-01-01

    Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem. (Author)

  19. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    Directory of Open Access Journals (Sweden)

    Navalpotro, H.

    2016-04-01

    Full Text Available Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem.

  20. Comparing prey composition and prey size delivered to nestlings by great tits, Parus major, and blue tits, Cyanistes caeruleus, in a Mediterranean sclerophyllous mixed forest

    Energy Technology Data Exchange (ETDEWEB)

    Navalpotro, H.; Pagani-Nuñez, E.; Hernandez-Gomez, S.; Senar, J.C.

    2016-07-01

    Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have been classical model species in studies of trophic competence. However, most studies on the topic have been conducted at localities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests, nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits, at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlap of these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than those of great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought more spiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great tits can prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioning by great and blue tits in sclerophyllous Mediterranean forest ecosystem. (Author)

  1. Survival probability of Baltic larval cod in relation to spatial overlap patterns with their prey obtained from drift model studies

    DEFF Research Database (Denmark)

    Hinrichsen, H.H.; Schmidt, J.O.; Petereit, C.

    2005-01-01

    Temporal mismatch between the occurrence of larvae and their prey potentially affects the spatial overlap and thus the contact rates between predator and prey. This might have important consequences for growth and survival. We performed a case study investigating the influence of circulation......-prey overlap, dependent on the hatching time of cod larvae. By performing model runs for the years 1979-1998 investigated the intra- and interannual variability of potential spatial overlap between predator and prey. Assuming uniform prey distributions, we generally found the overlap to have decreased since...

  2. Pattern formation induced by cross-diffusion in a predator–prey system

    International Nuclear Information System (INIS)

    Sun Guiquan; Jin Zhen; Liu Quanxing; Li Li

    2008-01-01

    This paper considers the Holling–Tanner model for predator–prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients. However, combined with cross-diffusion, it shows that the system will exhibit spotted pattern by both mathematical analysis and numerical simulations. Furthermore, asynchrony of the predator and the prey in the space. The obtained results show that cross-diffusion plays an important role on the pattern formation of the predator–prey system. (general)

  3. Prey exoskeletons influence the course of gastric evacuation in Atlantic cod Gadus morhua

    DEFF Research Database (Denmark)

    Couturier, C. S.; Andersen, N. G.; Audet, C.

    2013-01-01

    species, Pandalus borealis, Pandalus montagui and Eualus macilentus, and the crab Chionoecetes opilio, were evacuated from the stomach at different rates. The duration of all stages increased with increasing ash (and carbonate) content of the fresh prey. Thickness, chemical composition and morphology...... of the prey exoskeleton all affected gastric evacuation: duration of initial delay, overall evacuation rate and a decreased evacuation rate at the end of the process. The power exponential function (PEF), with its shape parameter, described the course of evacuation for these prey types well, especially...

  4. Prey Preferences of the Snow Leopard (Panthera uncia): Regional Diet Specificity Holds Global Significance for Conservation

    OpenAIRE

    Lyngdoh, Salvador; Shrotriya, Shivam; Goyal, Surendra P.; Clements, Hayley; Hayward, Matthew W.; Habib, Bilal

    2014-01-01

    The endangered snow leopard is a large felid that is distributed over 1.83 million km(2) globally. Throughout its range it relies on a limited number of prey species in some of the most inhospitable landscapes on the planet where high rates of human persecution exist for both predator and prey. We reviewed 14 published and 11 unpublished studies pertaining to snow leopard diet throughout its range. We calculated prey consumption in terms of frequency of occurrence and biomass consumed based o...

  5. The nutritional nexus: linking niche, habitat variability and prey composition in a generalist marine predator.

    Science.gov (United States)

    Machovsky-Capuska, Gabriel E; Miller, Mark G R; Silva, Fabiola R O; Amiot, Christophe; Stockin, Karen A; Senior, Alistair M; Schuckard, Rob; Melville, David; Raubenheimer, David

    2018-06-05

    1.Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remains a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour are critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey ("prey composition niche", defined as the range of prey compositions eaten), and diet ("realized nutritional niche" is the range of diets composed through feeding on the prey). 2.Here we studied adult-chick rearing Australasian gannets (Morus serrator) to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e., prey composition and nutritional niche breadth), habitat use and foraging behavior. 3.We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. 4.Across seasons, we established "nutritional landscapes" (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein to-lipid ratio -P:L-) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0 to 150 m). 5.During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. 6.Our findings are consistent with previous suggestions that dietary generalism

  6. Using insect traps to increase weaver ant (Oecophylla longinoda) prey capture

    DEFF Research Database (Denmark)

    Lynegaard, Gina; Offenberg, Joachim; Fast, Thora

    2014-01-01

    Weaver ants (Oecophylla spp.) are managed in plantations to control insect pests and are sometimes harvested as a protein rich food source. In both cases, the amount of insect prey caught by the ants is imperative for returns, as more prey leads to more effective biocontrol and to a higher...... by O. longinoda under natural conditions (without traps), potentially increasing to 14% if ants learn to extract all insects. Thus, prey intake may be increased with 5-14% per 3.9 USD invested in traps. These numbers increased to 38 and 78%, respectively, when light was used to attract insects during...

  7. Type of prey influences biology and consumption rate of Orius insidiosus (Say (Hemiptera, Anthocoridae

    Directory of Open Access Journals (Sweden)

    Simone M. Mendes

    2002-01-01

    Full Text Available Generalist predators are capable of consuming different types of prey, and as each prey may have distinct nutritional values, each may have a distinct impact on the biology of the predator. Therefore, the aim of this study was to determine how the consumption of different prey influences certain biological characteristics and the predatory capacity of Orius insidiosus (Say. The investigation was performed in climatic chamber at 25 ±1 ºC, RH 70 ± 10% and fotophase 12. Eggs of Anagasta kuehniella (Zeller, adults of Caliothrips phaseoli (Hood and nymphs of Aphis gossypii Glover were used as prey and were provided daily ad libitum for all the mobile stages of the predator. The results showed that biological parameters of O. insidiosus are affected differently depending on the type of prey ingested. The development time of the nymphal stage was 13.1, 11.23 and 10.25 days for O. insidiosus feeding on eggs of A. kuehniella, nymphs of A. gossypii and adults of C. phaseoli, respectively. Longevity was five times larger for adults fed on eggs of A. kuehniella (56.25 days compared to that of adults that preyed on nymphs of A. gossypii (11.44 days, and four times larger when the prey were adults of C. phaseoli (13.58 days. The consumption of eggs of A. kuehniella by predator females resulted in a shorter pre-oviposition period (3.2 days and a longer oviposition period (44.4 days when compared to the consumption of other types of prey. In addition, fecundity was increased with the consumption of eggs of A. kuehniella (195.25 eggs laid / female when compared to feeding on the other prey, C. phaseoli (70.00 eggs laid / female or A. gossypii (22.50 eggs laid / female. However, the consumption of aphids was larger (148.28 nymphs/ nymphal stage than that of thrips (74.10 thrips / nymphal stage or eggs of A. kuehniella (37.03 eggs /nymphal stage for all of the nymphal stages of the predator. The results indicate that the eggs of A. kuehniella are the type of

  8. Stochastic population dynamics in spatially extended predator-prey systems

    Science.gov (United States)

    Dobramysl, Ulrich; Mobilia, Mauro; Pleimling, Michel; Täuber, Uwe C.

    2018-02-01

    Spatially extended population dynamics models that incorporate demographic noise serve as case studies for the crucial role of fluctuations and correlations in biological systems. Numerical and analytic tools from non-equilibrium statistical physics capture the stochastic kinetics of these complex interacting many-particle systems beyond rate equation approximations. Including spatial structure and stochastic noise in models for predator-prey competition invalidates the neutral Lotka-Volterra population cycles. Stochastic models yield long-lived erratic oscillations stemming from a resonant amplification mechanism. Spatially extended predator-prey systems display noise-stabilized activity fronts that generate persistent correlations. Fluctuation-induced renormalizations of the oscillation parameters can be analyzed perturbatively via a Doi-Peliti field theory mapping of the master equation; related tools allow detailed characterization of extinction pathways. The critical steady-state and non-equilibrium relaxation dynamics at the predator extinction threshold are governed by the directed percolation universality class. Spatial predation rate variability results in more localized clusters, enhancing both competing species’ population densities. Affixing variable interaction rates to individual particles and allowing for trait inheritance subject to mutations induces fast evolutionary dynamics for the rate distributions. Stochastic spatial variants of three-species competition with ‘rock-paper-scissors’ interactions metaphorically describe cyclic dominance. These models illustrate intimate connections between population dynamics and evolutionary game theory, underscore the role of fluctuations to drive populations toward extinction, and demonstrate how space can support species diversity. Two-dimensional cyclic three-species May-Leonard models are characterized by the emergence of spiraling patterns whose properties are elucidated by a mapping onto a complex

  9. Effects of attitudes and demography on public support for endangered species conservation.

    Science.gov (United States)

    Liordos, Vasilios; Kontsiotis, Vasileios J; Anastasiadou, Magdalini; Karavasias, Efstathios

    2017-10-01

    It is critical for managers to understand how attitudes and demography affect public's preferences for species protection for designing successful conservation projects. 1080 adults in Greece were asked to rate pictures of 12 endangered species on aesthetic and negativistic attitudes, and intention to support their conservation. Factor analysis identified a group of animals for which respondents indicated high levels of support for their conservation (red deer, loggerhead sea turtle, brown bear, common pheasant, European ground squirrel, glossy ibis) and a group of animals for which respondents indicated low levels of support (black vulture, great white shark, fire-bellied toad, western barbastelle, Cretan tube web spider, Milos viper). The species that received the highest support were also rated as the most attractive and safest, excluding the fearsome brown bear. Structural models revealed that aesthetic, moralistic and negativistic attitudes were the stronger predictors of support. Aesthetic and moralistic attitudes were positively, and negativistic attitudes negatively, correlated with support for conservation in both groups. Consumptive users scored lower in aesthetics and were less supportive of protection in the high support group, while nonconsumptive users showed the opposite trend. Respondents residing in urban areas deemed animals of high support more attractive and less fearsome and were more supportive of conservation than rural residents in both groups. Females of higher education viewed animals of low support as fearsome, however they supported their conservation. Our study identified popular species that can be used as flagship species to facilitate the implementation of conservation projects. The results of this study could also be used to design a communication and outreach campaign to raise awareness about the ecosystem value of less attractive species. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Signals of forest degradation in the demography of common Asian amphibians

    Directory of Open Access Journals (Sweden)

    Nancy E. Karraker

    2018-01-01

    Full Text Available Background Lowland areas in tropical East and Southeast Asia have a long history of conversion from forestland to agricultural land, with many remaining forests being chronically degraded by wood cutting, livestock grazing, and burning. Wetland-breeding amphibians that have evolved in lowland forests in the region have adjusted to changes in habitat composition caused by humans’ activities, and populations continue to persist. However, we have little understanding of the impacts of forest disturbance on these species beyond assessments of abundance and distribution, and species considered to be common and widespread have been largely neglected. Methods We examined body condition and sex ratios of toads (Duttaphrynus melanostictus, predation risk in treefrogs (2 Polypedates spp., and growth and survival of leaf litter frogs (2 Microhyla spp. in agricultural land, degraded forest, and intact forest in two study areas, Thailand and Hong Kong. Results Toad populations exhibited higher body condition and female-biased sex ratios in intact forest. Predation of treefrog embryos by flies was lower in intact and degraded forests than in agricultural land. Embryonic survival and larval growth and survival in leaf litter frogs were lower in intact forests than in agricultural land. Results for each study were similar between study areas. Discussion For three of five of these common amphibian species, we documented signals of forest loss and disturbance in their populations. Although these species occur in disturbed habitats, loss of forest cover continues to degrade aspects of their population demography. We urge conservation biologists to consider that populations of species appearing to be common, widespread, and tolerant of human disturbance may be eroding over time.

  11. Population Structure and Historical Demography of the Oriental River Prawn (Macrobrachium nipponense) in Taiwan

    Science.gov (United States)

    Chu, Ta-Jen; Wang, Daryi; Lee, Ying-Chou; Tzeng, Tzong-Der

    2015-01-01

    The oriental river prawn (Macrobrachium nipponense) is a non-obligatory amphidromous prawn, and it has a wide distribution covering almost the entire Taiwan. Mitochondrial DNA fragment sequences of the cytochrome oxidase subunit I (COI) and 16S rRNA were combined and used to elucidate the population structure and historical demography of oriental river prawn in Taiwan. A total of 202 individuals from six reservoirs and three estuaries were separately collected. Nucleotide diversity (π) of all populations was 0.01217, with values ranging from 0.00188 (Shihmen Reservoir, SMR, northern Taiwan) to 0.01425 (Mingte Reservoir, MTR, west-central Taiwan). All 76 haplotypes were divided into 2 lineages: lineage A included individuals from all sampling areas except SMR, and lineage B included specimens from all sampling locations except Chengching Lake Reservoir (CLR) and Liyu Lake Reservoir (LLR). All F ST values among nine populations were significantly different except the one between Jhonggang River Estuary (JGE, west-central Taiwan) and Kaoping River Estuary (KPE, southern Taiwan). UPGMA tree of nine populations showed two main groups: the first group included the SMR and Tamsui River Estuary (TSE) (both located northern Taiwan), and the second one included the other seven populations (west-central, southern and eastern Taiwan). Demographic analyses implied a population expansion occurred during the recent history of the species. The dispersal route of this species might be from China to west-central and west-southern Taiwan, and then the part individuals belonging to lineage A and B dispersed southerly and northerly, respectively. And then part individuals in west-central Taiwan fell back to and stay at estuaries as the sea level rose about 18,000 years ago. PMID:26716687

  12. Using demography and movement behavior to predict range expansion of the southern sea otter.

    Science.gov (United States)

    Tinker, M.T.; Doak, D.F.; Estes, J.A.

    2008-01-01

    In addition to forecasting population growth, basic demographic data combined with movement data provide a means for predicting rates of range expansion. Quantitative models of range expansion have rarely been applied to large vertebrates, although such tools could be useful for restoration and management of many threatened but recovering populations. Using the southern sea otter (Enhydra lutris nereis) as a case study, we utilized integro-difference equations in combination with a stage-structured projection matrix that incorporated spatial variation in dispersal and demography to make forecasts of population recovery and range recolonization. In addition to these basic predictions, we emphasize how to make these modeling predictions useful in a management context through the inclusion of parameter uncertainty and sensitivity analysis. Our models resulted in hind-cast (1989–2003) predictions of net population growth and range expansion that closely matched observed patterns. We next made projections of future range expansion and population growth, incorporating uncertainty in all model parameters, and explored the sensitivity of model predictions to variation in spatially explicit survival and dispersal rates. The predicted rate of southward range expansion (median = 5.2 km/yr) was sensitive to both dispersal and survival rates; elasticity analysis indicated that changes in adult survival would have the greatest potential effect on the rate of range expansion, while perturbation analysis showed that variation in subadult dispersal contributed most to variance in model predictions. Variation in survival and dispersal of females at the south end of the range contributed most of the variance in predicted southward range expansion. Our approach provides guidance for the acquisition of further data and a means of forecasting the consequence of specific management actions. Similar methods could aid in the management of other recovering populations.

  13. Modelling the growth of Populus species using Ecosystem Demography (ED) model

    Science.gov (United States)

    Wang, D.; Lebauer, D. S.; Feng, X.; Dietze, M. C.

    2010-12-01

    Hybrid poplar plantations are an important source being evaluated for biomass production. Effective management of such plantations requires adequate growth and yield models. The Ecosystem Demography model (ED) makes predictions about the large scales of interest in above- and belowground ecosystem structure and the fluxes of carbon and water from a description of the fine-scale physiological processes. In this study, we used a workflow management tool, the Predictive Ecophysiological Carbon flux Analyzer (PECAn), to integrate literature data, field measurement and the ED model to provide predictions of ecosystem functioning. Parameters for the ED ensemble runs were sampled from the posterior distribution of ecophysiological traits of Populus species compiled from the literature using a Bayesian meta-analysis approach. Sensitivity analysis was performed to identify the parameters which contribute the most to the uncertainties of the ED model output. Model emulation techniques were used to update parameter posterior distributions using field-observed data in northern Wisconsin hybrid poplar plantations. Model results were evaluated with 5-year field-observed data in a hybrid poplar plantation at New Franklin, MO. ED was then used to predict the spatial variability of poplar yield in the coterminous United States (United States minus Alaska and Hawaii). Sensitivity analysis showed that root respiration, dark respiration, growth respiration, stomatal slope and specific leaf area contribute the most to the uncertainty, which suggests that our field measurements and data collection should focus on these parameters. The ED model successfully captured the inter-annual and spatial variability of the yield of poplar. Analyses in progress with the ED model focus on evaluating the ecosystem services of short-rotation woody plantations, such as impacts on soil carbon storage, water use, and nutrient retention.

  14. Madeiran Arabidopsis thaliana reveals ancient long-range colonization and clarifies demography in Eurasia.

    Science.gov (United States)

    Fulgione, Andrea; Koornneef, Maarten; Roux, Fabrice; Hermisson, Joachim; Hancock, Angela M

    2017-12-05

    The study of model organisms on islands may shed light on rare long-range dispersal events, uncover signatures of local evolutionary processes, and inform demographic inference on the mainland. Here, we sequenced the genomes of Arabidopsis thaliana samples from the oceanic island of Madeira. These samples include the most diverged worldwide, likely a result of long isolation on the island. We infer that colonisation of Madeira happened between 70 and 85 kya, consistent with a propagule dispersal model (of size > =10), or with an ecological window of opportunity. This represents a clear example of a natural long-range dispersal event in A. thaliana. Long-term effective population size on the island, rather than the founder effect, had the greatest impact on levels of diversity, and rates of coalescence. Our results uncover a selective sweep signature on the ancestral haplotype of a known translocation in Eurasia, as well as the possible importance of the low phosphorous availability in volcanic soils, and altitude, in shaping early adaptations to the island conditions. Madeiran genomes, sheltered from the complexities of continental demography, help illuminate ancient demographic events in Eurasia. Our data support a model in which two separate lineages of A. thaliana, one originating in Africa and the other from the Caucasus expanded and met in Iberia, resulting in a secondary contact zone there. While previous studies inferred that the westward expansion of A. thaliana coincided with the spread of human agriculture, our results suggest it happened much earlier (20-40 kya). © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  15. Type 2 diabetes in young adults in Central Auckland: demography and complications.

    Science.gov (United States)

    Beig, Junaid; Khanolkar, Manish; Cundy, Tim

    2018-01-01

    Type 2 diabetes (T2D) in young adults is associated with a high risk of diabetes complications. To investigated the demography and the emergence of complications of young adults with T2D in the central Auckland region where there has been substantial immigration. In total, 310 young adults with T2D (Auckland Diabetes Centre in 2015. We documented demographic, anthropometric and metabolic variables and prevalence and the emergence of complications. Three demographic groups accounted for 243 participants (78%): 135 (44%) were migrants of Asian or Pacific Island origin, diagnosed a median 9 years after migration at a mean age of 28 ± 6 years; 88 (29%) were New Zealand-born Pāsifika descent, with a high prevalence of morbid obesity and 37 (12%) had major mental illness or intellectual disability. At diagnosis, the median HbA1c was 80 mmol/mol, and in 28%, it was ≥100 mmol/mol. A median 6 years after diagnosis, 56% had some degree of retinopathy, with the prevalence related both to the duration of diabetes and glycaemic control (P = 0.001). Forty-four percent of subjects had abnormal albuminuria at diagnosis (12% with macroalbuminuria). Increased albuminuria was strongly associated with obesity (P = 0.002). The development of CKD stages 4-5 was related both to the severity of retinopathy and degree of albuminuria at diagnosis (P = 0.0001). Major cardiovascular events were related to the severity of retinopathy at diagnosis (P = 0.0001). New migrants, New Zealand-born Pāsifika and patients with mental illness or an intellectual disability comprise the bulk of young onset T2D. The disease is aggressive, and by the age of 40, patients are already developing advanced complications. © 2017 Royal Australasian College of Physicians.

  16. Biological invasion by Myrica faya in Hawaii: Plant demography, nitrogen fixation, ecosystem effects

    International Nuclear Information System (INIS)

    Vitousek, P.M.; Walker, L.R.

    1989-01-01

    Myrica faya, an introduced actinorhizal nitrogen fixer, in invading young volcanic sites in Hawaii Volcanoes National Park. We examined the population biology of the invader and ecosystem-level consequences of its invasion in open-canopied forests resulting from volcanic cinder-fall. Although Myrica faya is nominally dioecious, both males and females produce large amounts of fruit that are utilized by a number of exotic and native birds, particularly the exotic Zosterops japonica. In areas of active colonization, Myrica seed rain under perch trees of the dominant native Metrosideros polymorpha ranged from 6 to 60 seeds m -2 yr -1 ; no seeds were captured in the open. Planted seeds of Myrica also germinated an established better under isolated individuals of Metrosideros than in the open. Diameter growth of Myrica is > 15-fold greater than that of Metrosideros, and the Myrica population is increasing rapidly. Rates of nitrogen fixation were measured using the acetylene reduction assay calibrated with 15 N. Myrica nodules reduced acetylene at between 5 and 20 μmol g -1 h -1 , a rate that extrapolated to nitrogen fixation of 18 kg ha -1 in a densely colonized site. By comparison, all native sources of nitrogen fixation summed to 0.2 kg ha -1 yr -1 , and precipitation added -1 yr -1 . Measurements of litter decomposition and nitrogen release, soil nitrogen mineralization, and plant growth in bioassays all demonstrated that nitrogen fixed by Myrica becomes available to other organisms as well. We conclude that biological invasion by Myrica faya alters ecosystem-level properties in this young volcanic area; at least in this case, the demography and physiology of one species controls characteristics of a whole ecosystem

  17. Interactions between social structure, demography, and transmission determine disease persistence in primates.

    Science.gov (United States)

    Ryan, Sadie J; Jones, James H; Dobson, Andrew P

    2013-01-01

    Catastrophic declines in African great ape populations due to disease outbreaks have been reported in recent years, yet we rarely hear of similar disease impacts for the more solitary Asian great apes, or for smaller primates. We used an age-structured model of different primate social systems to illustrate that interactions between social structure and demography create 'dynamic constraints' on the pathogens that can establish and persist in primate host species with different social systems. We showed that this varies by disease transmission mode. Sexually transmitted infections (STIs) require high rates of transmissibility to persist within a primate population. In particular, for a unimale social system, STIs require extremely high rates of transmissibility for persistence, and remain at extremely low prevalence in small primates, but this is less constrained in longer-lived, larger-bodied primates. In contrast, aerosol transmitted infections (ATIs) spread and persist at high prevalence in medium and large primates with moderate transmissibility;, establishment and persistence in small-bodied primates require higher relative rates of transmissibility. Intragroup contact structure - the social network - creates different constraints for different transmission modes, and our model underscores the importance of intragroup contacts on infection prior to intergroup movement in a structured population. When alpha males dominate sexual encounters, the resulting disease transmission dynamics differ from when social interactions are dominated by mother-infant grooming events, for example. This has important repercussions for pathogen spread across populations. Our framework reveals essential social and demographic characteristics of primates that predispose them to different disease risks that will be important for disease management and conservation planning for protected primate populations.

  18. Oregon Spotted Frog (Rana pretiosa) movement and demography at Dilman Meadow: Implications for future monitoring

    Science.gov (United States)

    Chelgren, Nathan D.; Pearl, Christopher A.; Bowerman, Jay; Adams, Michael J.

    2007-01-01

    From 2001 to 2005, we studied the demography and seasonal movement of Oregon spotted frogs (Rana pretiosa) translocated into created ponds in Dilman Meadow in central Oregon. Our objectives were to inform future monitoring and management at the site, and to elucidate poorly known aspects of the species’ population ecology. Movement rates revealed complementary use of sites seasonally, with one small spring being preferred during winter that was rarely used during the rest of the year. Growth rates were significantly higher in ponds that were not used for breeding, and larger size resulted in significantly higher survival. When variation in survival by size was accounted for there was little variation among ponds in survival. Seasonal estimates of survival were lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. Overwintering survival for both genders was relatively high. Our study supports others in suggesting Oregon spotted frogs are specific in their overwintering habitat requirements, and that predator-free springs may be of particular value. We suggest that any future monitoring include measures of the rate of pond succession. Demographic monitoring should include metrics of both frog reproduction and survival: counts of egg masses at all ponds during spring, and capture-recapture study of survival in mid and late summer when capture rates are highest. Additional study of early life stages would be particularly useful to broaden our understanding of the species’ ecology. Specifically, adding intensive capture and marking effort after larval transformation in fall would enable a full understanding of the annual life cycle. Complete study of the annual life cycle is needed to isolate the life stages and mechanisms through which Oregon spotted frogs are affected by stressors such as nonnative predators. Dilman Meadow, which lacks many hypothesized stressors, is an important reference for

  19. Functional traits help predict post-disturbance demography of tropical trees.

    Science.gov (United States)

    Flores, Olivier; Hérault, Bruno; Delcamp, Matthieu; Garnier, Éric; Gourlet-Fleury, Sylvie

    2014-01-01

    How tropical tree species respond to disturbance is a central issue of forest ecology, conservation and resource management. We define a hierarchical model to investigate how functional traits measured in control plots relate to the population change rate and to demographic rates for recruitment and mortality after disturbance by logging operations. Population change and demographic rates were quantified on a 12-year period after disturbance and related to seven functional traits measured in control plots. The model was calibrated using a Bayesian Network approach on 53 species surveyed in permanent forest plots (37.5 ha) at Paracou in French Guiana. The network analysis allowed us to highlight both direct and indirect relationships among predictive variables. Overall, 89% of interspecific variability in the population change rate after disturbance were explained by the two demographic rates, the recruitment rate being the most explicative variable. Three direct drivers explained 45% of the variability in recruitment rates, including leaf phosphorus concentration, with a positive effect, and seed size and wood density with negative effects. Mortality rates were explained by interspecific variability in maximum diameter only (25%). Wood density, leaf nitrogen concentration, maximum diameter and seed size were not explained by variables in the analysis and thus appear as independent drivers of post-disturbance demography. Relationships between functional traits and demographic parameters were consistent with results found in undisturbed forests. Functional traits measured in control conditions can thus help predict the fate of tropical tree species after disturbance. Indirect relationships also suggest how different processes interact to mediate species demographic response.

  20. Selenium assimilation and loss by an insect predator and its relationship to Se subcellular partitioning in two prey types

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, Maitee [Institut national de la recherche scientifique - Eau, Terre et Environnement, Universite du Quebec, Quebec City, Quebec, G1K 9A9 (Canada); Hare, Landis [Institut national de la recherche scientifique - Eau, Terre et Environnement, Universite du Quebec, Quebec City, Quebec, G1K 9A9 (Canada)], E-mail: landis@ete.inrs.ca

    2009-03-15

    Subcellular selenium (Se) distributions in the oligochaete Tubifex tubifex and in the insect Chironomus riparius did not vary with Se exposure duration, which was consistent with the observations that the duration of prey Se exposure had little influence on either Se assimilation or loss by a predatory insect (the alderfly Sialis velata). However, these two prey types differed in how Se was distributed in their cells. Overall, the predator assimilated a mean of 66% of the Se present in its prey, which was similar to the mean percentage of Se in prey cells (62%) that was theoretically available for uptake (that is, Se in the protein and organelle fractions). Likewise, data for cadmium, nickel and thallium suggest that predictions of trace element transfer between prey and predator are facilitated by considering the subcellular partitioning of these contaminants in prey cells. - Selenium assimilation by a predatory aquatic insect depends on Se availability in the cells of its prey.

  1. Selenium assimilation and loss by an insect predator and its relationship to Se subcellular partitioning in two prey types

    International Nuclear Information System (INIS)

    Dubois, Maitee; Hare, Landis

    2009-01-01

    Subcellular selenium (Se) distributions in the oligochaete Tubifex tubifex and in the insect Chironomus riparius did not vary with Se exposure duration, which was consistent with the observations that the duration of prey Se exposure had little influence on either Se assimilation or loss by a predatory insect (the alderfly Sialis velata). However, these two prey types differed in how Se was distributed in their cells. Overall, the predator assimilated a mean of 66% of the Se present in its prey, which was similar to the mean percentage of Se in prey cells (62%) that was theoretically available for uptake (that is, Se in the protein and organelle fractions). Likewise, data for cadmium, nickel and thallium suggest that predictions of trace element transfer between prey and predator are facilitated by considering the subcellular partitioning of these contaminants in prey cells. - Selenium assimilation by a predatory aquatic insect depends on Se availability in the cells of its prey

  2. A Sensory-Driven Trade-Off between Coordinated Motion in Social Prey and a Predator's Visual Confusion.

    Directory of Open Access Journals (Sweden)

    Bertrand H Lemasson

    2016-02-01

    Full Text Available Social animals are capable of enhancing their awareness by paying attention to their neighbors, and prey found in groups can also confuse their predators. Both sides of these sensory benefits have long been appreciated, yet less is known of how the perception of events from the perspectives of both prey and predator can interact to influence their encounters. Here we examined how a visual sensory mechanism impacts the collective motion of prey and, subsequently, how their resulting movements influenced predator confusion and capture ability. We presented virtual prey to human players in a targeting game and measured the speed and accuracy with which participants caught designated prey. As prey paid more attention to neighbor movements their collective coordination increased, yet increases in prey coordination were positively associated with increases in the speed and accuracy of attacks. However, while attack speed was unaffected by the initial state of the prey, accuracy dropped significantly if the prey were already organized at the start of the attack, rather than in the process of self-organizing. By repeating attack scenarios and masking the targeted prey's neighbors we were able to visually isolate them and conclusively demonstrate how visual confusion impacted capture ability. Delays in capture caused by decreased coordination amongst the prey depended upon the collection motion of neighboring prey, while it was primarily the motion of the targets themselves that determined capture accuracy. Interestingly, while a complete loss of coordination in the prey (e.g., a flash expansion caused the greatest delay in capture, such behavior had little effect on capture accuracy. Lastly, while increases in collective coordination in prey enhanced personal risk, traveling in coordinated groups was still better than appearing alone. These findings demonstrate a trade-off between the sensory mechanisms that can enhance the collective properties that

  3. Let's go beyond taxonomy in diet description: testing a trait-based approach to prey-predator relationships.

    Science.gov (United States)

    Spitz, Jérôme; Ridoux, Vincent; Brind'Amour, Anik

    2014-09-01

    Understanding 'Why a prey is a prey for a given predator?' can be facilitated through trait-based approaches that identify linkages between prey and predator morphological and ecological characteristics and highlight key functions involved in prey selection. Enhanced understanding of the functional relationships between predators and their prey is now essential to go beyond the traditional taxonomic framework of dietary studies and to improve our knowledge of ecosystem functioning for wildlife conservation and management. We test the relevance of a three-matrix approach in foraging ecology among a marine mammal community in the northeast Atlantic to identify the key functional traits shaping prey selection processes regardless of the taxonomy of both the predators and prey. Our study reveals that prey found in the diet of marine mammals possess functional traits which are directly and significantly linked to predator characteristics, allowing the establishment of a functional typology of marine mammal-prey relationships. We found prey selection of marine mammals was primarily shaped by physiological and morphological traits of both predators and prey, confirming that energetic costs of foraging strategies and muscular performance are major drivers of prey selection in marine mammals. We demonstrate that trait-based approaches can provide a new definition of the resource needs of predators. This framework can be used to anticipate bottom-up effects on marine predator population dynamics and to identify predators which are sensitive to the loss of key prey functional traits when prey availability is reduced. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

  4. Polybrominated diphenyl ethers in birds of prey from Northern China.

    Science.gov (United States)

    Chen, Da; Mai, Bixian; Song, Jie; Sun, Quanhui; Luo, Yong; Luo, Xiaojun; Zeng, Eddy Y; Hale, Robert C

    2007-03-15

    Birds of prey from Northern China (Beijing area) were examined for polybrominated diphenyl ethers (PBDEs). A total of 47 specimens from eight different species were analyzed. Muscle and liver were analyzed separately for each bird. Kidneys were pooled by species. Common kestrels exhibited the highest PBDE levels (mean muscle and liver concentrations of 12300 and 12200 ng/g lipid weight, respectively), with maxima in an individual bird of 31700 in muscle and 40900 ng/g lw in liver. Congener profiles differed between some species, but were generally dominated by the more brominated congeners (e.g., BDE-153, -209, -183, -207). BDE-209 was especially elevated compared to other published reports. Interspecies differences in congener concentrations and profiles may be due to diet, behavior, or biotransformation capacities. BDE-209 was detected in 79.4% of the samples. Common kestrels contained the highest BDE-209 levels (mean/maxima of 2150/6220 in muscle and 2870/12200 ng/g lw in liver). BDE-209 was the dominant congener in tissues from some buzzards, scops owls, and long-eared owls. It was the second most abundant congener in common kestrels. The remarkable levels and dominance of BDE-209 may relate to significant production, usage, or disposal of deca-containing products in China. These observations reinforce the growing view that organisms using terrestrial food chains may have greater exposure to BDE-209.

  5. Falco sparverius (Aves: Falconiformes preying upon Nyctinomops laticaudatus (Chiroptera: Molossidae

    Directory of Open Access Journals (Sweden)

    Ludmilla Moura de Souza Aguiar

    2012-04-01

    Full Text Available In Brazil, there are two published references on the diet of American kestrel falcons, Falco sparverius Linnaeus, 1758, and one is for the Cerrado biome. The only mammal prey so far found in the diet of F. sparverius was the rodent Calomys tener (Winge, 1887. Herein we report on daily hunting activities by American kestrel falcons at a factory in the city of Uberlândia, state of Minas Gerais, southeastern Brazil, during an attempt to remove a bat colony. Two American kestrel falcons were observed on 14 occasions during two consecutive days: in two of these occasions, they were hunting in pairs, from 12:00 p.m. to 3:00 p.m. on 06/X/2003, and from 07:00 a.m. to 11:00 a.m. on 07/X/2003. During this period, American kestrel falcons made 27 hunting attempts and captured four bats of the same species, Nyctinomops laticaudatus (E. Geoffroy St.-Hilaire, 1805 (14.81% success. This report corroborates observations made in the Northern hemisphere, where bats are a dietary item of this falcon. Our findings are noteworthy because they reveal that the known natural predators of bats are few not only in Brazil but also worldwide.

  6. Embedding recurrent neural networks into predator-prey models.

    Science.gov (United States)

    Moreau, Yves; Louiès, Stephane; Vandewalle, Joos; Brenig, Leon

    1999-03-01

    We study changes of coordinates that allow the embedding of ordinary differential equations describing continuous-time recurrent neural networks into differential equations describing predator-prey models-also called Lotka-Volterra systems. We transform the equations for the neural network first into quasi-monomial form (Brenig, L. (1988). Complete factorization and analytic solutions of generalized Lotka-Volterra equations. Physics Letters A, 133(7-8), 378-382), where we express the vector field of the dynamical system as a linear combination of products of powers of the variables. In practice, this transformation is possible only if the activation function is the hyperbolic tangent or the logistic sigmoid. From this quasi-monomial form, we can directly transform the system further into Lotka-Volterra equations. The resulting Lotka-Volterra system is of higher dimension than the original system, but the behavior of its first variables is equivalent to the behavior of the original neural network. We expect that this transformation will permit the application of existing techniques for the analysis of Lotka-Volterra systems to recurrent neural networks. Furthermore, our results show that Lotka-Volterra systems are universal approximators of dynamical systems, just as are continuous-time neural networks.

  7. Recolonizing carnivores and naïve prey: conservation lessons from Pleistocene extinctions.

    Science.gov (United States)

    Berger, J; Swenson, J E; Persson, I L

    2001-02-09

    The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction.

  8. New scalaranes from the nudibranch Glossodoris atromarginata and its sponge Prey

    Digital Repository Service at National Institute of Oceanography (India)

    Fontana, A.; Cavaliere, P.; Ungur, N.; DeSouza, L.; Parameswaran, P.S.; Cimino, G.

    Two new scalaranes (1 and 2) have been isolated from the dorid nudibranch Glossodoris atromarginata and its prey. The structures were determined by spectral techniques and confirmed by chemical methods. Compounds 1 and 3 showed selective cytotoxic...

  9. Stability analysis of pest-predator interaction model with infectious disease in prey

    Science.gov (United States)

    Suryanto, Agus; Darti, Isnani; Anam, Syaiful

    2018-03-01

    We consider an eco-epidemiological model based on a modified Leslie-Gower predator-prey model. Such eco-epidemiological model is proposed to describe the interaction between pest as the prey and its predator. We assume that the pest can be infected by a disease or pathogen and the predator only eats the susceptible prey. The dynamical properties of the model such as the existence and the stability of biologically feasible equilibria are studied. The model has six type of equilibria, but only three of them are conditionally stable. We find that the predator in this system cannot go extinct. However, the susceptible or the infective prey may disappear in the environment. To support our analytical results, we perform some numerical simulations with different scenario.

  10. Time Delayed Stage-Structured Predator-Prey Model with Birth Pulse and Pest Control Tactics

    Directory of Open Access Journals (Sweden)

    Mei Yan

    2014-01-01

    Full Text Available Normally, chemical pesticides kill not only pests but also their natural enemies. In order to better control the pests, two-time delayed stage-structured predator-prey models with birth pulse and pest control tactics are proposed and analyzed by using impulsive differential equations in present work. The stability threshold conditions for the mature prey-eradication periodic solutions of two models are derived, respectively. The effects of key parameters including killing efficiency rate, pulse period, the maximum birth effort per unit of time of natural enemy, and maturation time of prey on the threshold values are discussed in more detail. By comparing the two threshold values of mature prey-extinction, we provide the fact that the second control tactic is more effective than the first control method.

  11. Natural enemy-mediated indirect interactions among prey species: potential for enhancing biocontrol services in agroecosystems

    NARCIS (Netherlands)

    Chailleux, A.; Mohl, E.K.; Teixeira Alves, M.; Messelink, G.J.; Desneux, N.

    2014-01-01

    Understanding how arthropod pests and their natural enemies interact in complex agroecosystems is essential for pest management programmes. Theory predicts that prey sharing a predator, such as a biological control agent, can indirectly reduce each other's density at equilibrium (apparent

  12. Allee effect in a discrete-time predator-prey system

    International Nuclear Information System (INIS)

    Celik, Canan; Duman, Oktay

    2009-01-01

    In this paper, we study the stability of a discrete-time predator-prey system with and without Allee effect. By analyzing both systems, we first obtain local stability conditions of the equilibrium points without the Allee effect and then exhibit the impact of the Allee effect on stability when it is imposed on prey population. We also show the stabilizing effect of Allee effect by numerical simulations and verify that when the prey population is subject to an Allee effect, the trajectory of the solutions approximates to the corresponding equilibrium point much faster. Furthermore, for some fixed parameter values satisfying necessary conditions, we show that the corresponding equilibrium point moves from instability to stability under the Allee effect on prey population.

  13. Complex dynamics of a stochastic discrete modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting

    Directory of Open Access Journals (Sweden)

    A. Elhassanein

    2014-06-01

    Full Text Available This paper introduced a stochastic discretized version of the modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting. The dynamical behavior of the proposed model was investigated. The existence and stability of the equilibria of the skeleton were studied. Numerical simulations were employed to show the model's complex dynamics by means of the largest Lyapunov exponents, bifurcations, time series diagrams and phase portraits. The effects of noise intensity on its dynamics and the intermittency phenomenon were also discussed via simulation.

  14. Resolution VII International Conference Working Group on Birds of Prey of Northern Eurasia “Birds of Prey of Northern Eurasia: Problems and Adaptation Under Modern Conditions”

    Directory of Open Access Journals (Sweden)

    Igor V. Karyakin

    2017-01-01

    Full Text Available From 19 to 24 September, 2016 VII International Conference of the Working Group on Raptors of Northern Eurasia “Birds of prey of Northern Eurasia: problems and adaptation under modern conditions” was held on the basis of the Sochi National Park. Materials for the conference were presented by 198 ornithologists from Russia, Ukraine, Belarus, Kazakhstan, Moldova, Turkmenistan, Austria, Great Britain, Hungary, Mongolia, Poland, Estonia and the USA, who published 148 articles in two collections “Birds of prey of Northern Eurasia” and “Palearctic Harriers”.

  15. Differential wolf-pack-size persistence and the role of risk when hunting dangerous prey

    Science.gov (United States)

    Barber-Meyer, Shannon M.; Mech, L. David; Newton, Wesley E.; Borg, Bridget

    2016-01-01

    Risk to predators hunting dangerous prey is an emerging area of research and could account for possible persistent differences in gray wolf (Canis lupus) pack sizes. We documented significant differences in long-term wolf-pack-size averages and variation in the Superior National Forest (SNF), Denali National Park and Preserve, Yellowstone National Park, and Yukon, Canada (pwolves’ risk when hunting primary prey, for those packs (N=3) hunting moose (Alces americanus) were significantly larger than those (N=10) hunting white-tailed deer (Odocoileus virginianus) (F1,8=16.50, p=0.004). Our data support the hypothesis that differential pack-size persistence may be perpetuated by differences in primary prey riskiness to wolves, and we highlight two important extensions of this idea: (1) the potential for wolves to provision and defend injured packmates from other wolves and (2) the importance of less-risky, buffer prey to pack-size persistence and year-to-year variation. Risk to predators hunting dangerous prey is an emerging area of research and could account for possible persistent differences in gray wolf (Canis lupus) pack sizes. We documented significant differences in long-term wolf-pack-size averages and variation in the Superior National Forest (SNF), Denali National Park and Preserve, Yellowstone National Park, and Yukon, Canada (pwolves’ risk when hunting primary prey, for those packs (N=3) hunting moose (Alces americanus) were significantly larger than those (N=10) hunting white-tailed deer (Odocoileus virginianus) (F1,8=16.50, p=0.004). Our data support the hypothesis that differential pack-size persistence may be perpetuated by differences in primary prey riskiness to wolves, and we highlight two important extensions of this idea: (1) the potential for wolves to provision and defend injured packmates from other wolves and (2) the importance of less-risky, buffer prey to pack-size persistence and year-to-year variation.

  16. A tiger beetle’s pursuit of prey depends on distance

    Science.gov (United States)

    Noest, R. M.; Wang, Z. Jane

    2017-04-01

    Tiger beetles pursue prey by adjusting their heading according to a time-delayed proportional control law that minimizes the error angle (Haselsteiner et al 2014 J. R. Soc. Interface 11 20140216). This control law can be further interpreted in terms of mechanical actuation: to catch prey, tiger beetles exert a sideways force by biasing their tripod gait in proportion to the error angle measured half a stride earlier. The proportional gain was found to be nearly optimal in the sense that it minimizes the time to point directly toward the prey. For a time-delayed linear proportional controller, the optimal gain, k, is inversely proportional to the time delay, τ, and satisfies kτ =1/e . Here we present evidence that tiger beetles adjust their control gain during their pursuit of prey. Our analysis shows two critical distances: one corresponding to the beetle’s final approach to the prey, and the second, less expected, occurring at a distance around 10 cm for a prey size of 4.5 mm. The beetle initiates its chase using a sub-critical gain and increases the gain to the optimal value once the prey is within this critical distance. Insects use a variety of methods to detect distance, often involving different visual cues. Here we examine two such methods: one based on motion parallax and the other based on the prey’s elevation angle. We show that, in order for the motion parallax method to explain the observed data, the beetle needs to correct for the ratio of the prey’s sideways velocity relative to its own. On the other hand, the simpler method based on the elevation angle can detect both the distance and the prey’s size. Moreover we find that the transition distance corresponds to the accuracy required to distinguish small prey from large predators.

  17. Barred Owl Habitat and Prey: A Review and Synthesis of the Literature

    OpenAIRE

    Livezey, Kent B.

    2007-01-01

    Barred Owls (Strix varia) historically inhabited the forests of eastern North America. During the last century, they expanded their range to include forests throughout the southern provinces of Canada, southeastern Alaska, British Columbia, Washington, Oregon, and northern California. To date, there has been no synthesis of the varied habitats or prey used by Barred Owls in their expanded range. Here I review and synthesize studies concerning habitat (N  =  114) and prey (N  =  43) of Barred ...

  18. Non-pest prey do not disrupt aphid predation by a web-building spider.

    Science.gov (United States)

    Welch, K D; Whitney, T D; Harwood, J D

    2016-02-01

    A generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

  19. Hopf bifurcation of a ratio-dependent predator-prey system with time delay

    International Nuclear Information System (INIS)

    Celik, Canan

    2009-01-01

    In this paper, we consider a ratio dependent predator-prey system with time delay where the dynamics is logistic with the carrying capacity proportional to prey population. By considering the time delay as bifurcation parameter, we analyze the stability and the Hopf bifurcation of the system based on the normal form approach and the center manifold theory. Finally, we illustrate our theoretical results by numerical simulations.

  20. Prey selection of lions Panthera leo in a small, enclosed reserve

    Directory of Open Access Journals (Sweden)

    R.J. Power

    2002-12-01

    Full Text Available Annual trends in numbers of ungulate species on a 15 km² reserve from 1993 to 1998, were evaluated in the context of lion Panthera leo reintroduction during 1996, and subsequent predation by them. The ungulate prey base was enumerated annually by aerial counts and a road count that took place during 1998. The lion prey record was obtained from direct observations of a radio-located pride of eight lions and daily reserve management records. All ungulate species that underwent precipituous declines were also the most important prey to lions, comprising over 80 % of their prey, and they were preyed upon according to their availability. Lion predation was causal for the declines in wildebeest Connochaetes taurinus, Blesbok Damaliscus pygargus phillipsi and Warthog Phacochoerus africana, while the decline in Kudu Tragelaphus strepsiceros was only partly ascribed to lions, as other non-lion related mortality sources were identified. The only ungulate species to increase subsequent to lion reintroduction was the Impala Aepyceros melampus, which was furthermore under-selected by lions. The uncontrolled population growth of Impala could have elicited ecological degradation, and it was advised to either not stock Impala, or otherwise control their numbers if lions are unable to do so. Lion hunting success and kill rate, were 21 % (n = 63 and 1 kill/4.4 days, respectively. Three bushpigs Potamochoerus larvatus were killed but not utilised,and this finding is corroborated by an intensive study in Kwazulu-Natal, and this aversion is discussed. Predators can cause unprecedented declines of their prey where the prey are confined to small reserves that have no refuge from predation. On an annual basis, prey may need to be augmented to sustain predators on small reserves

  1. Relationship of Course Woody Debris to Red-Cockaded Woodpecker Prey Diversity and Abundance

    Energy Technology Data Exchange (ETDEWEB)

    Horn, G.S.

    1999-09-03

    The abundance of diversity of prey commonly used by the red-cockaded woodpecker were monitored in experimental plots in which course woody debris was manipulated. In one treatment, all the woody debris over four inches was removed. In the second treatment, the natural amount of mortality remained intact. The overall diversity of prey was unaffected; however, wood roaches were significantly reduced by removal of woody debris. The latter suggests that intensive utilizations or harvesting practices may reduce foraging.

  2. A predator-prey system with stage-structure for predator and nonlocal delay

    DEFF Research Database (Denmark)

    Lin, Z.G.; Pedersen, Michael; Zhang, Lai

    2010-01-01

    This paper deals with the behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition, which describes a prey-predator model with nonlocal delay. Sufficient conditions for the global stability of each equilibrium are derived by the Lyapunov functional...... and the results show that the introduction of stage-structure into predator positively affects the coexistence of prey and predator. Numerical simulations are performed to illustrate the results....

  3. An unprecedented role reversal: ground beetle larvae (Coleoptera: Carabidae lure amphibians and prey upon them.

    Directory of Open Access Journals (Sweden)

    Gil Wizen

    Full Text Available Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae. Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal.

  4. Chemical basis of prey recognition in thamnophiine snakes: the unexpected new roles of parvalbumins.

    Directory of Open Access Journals (Sweden)

    Maïté Smargiassi

    Full Text Available Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO. In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins-parvalbumins-present in the cutaneous mucus of the common frog (Rana temporaria may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt water. These proteins are located in many tissues and function as Ca(2+ buffers. In addition, we clarified the intrinsic role of parvalbumins present in the cutaneous mucus of amphibians and fishes. We demonstrate that these Ca(2+-binding proteins participate in innate bacterial defense mechanisms by means of calcium chelation. We show that these parvalbumins are chemoattractive for three different thamnophiine snakes, suggesting that these chemicals play a key role in their prey-recognition mechanism. Therefore, we suggest that recognition of parvalbumin-like proteins or other calcium-binding proteins by the VNO could be a generalized prey-recognition process in snakes. Detecting innate prey defense mechanism compounds may have driven the evolution of this predator-prey interaction.

  5. Interactions among Behavioral Responses of Baleen Whales to Acoustic Stimuli, Oceanographic Features, and Prey Availability

    Science.gov (United States)

    2015-09-30

    understand, and effectively mitigate the affects of anthropogenic sound, including military sonar, on these animals . OBJECTIVES The overall...distribution and individual predator behavior has now been measured in portions of five field seasons of SOCAL-BRS. This has included two phases each in in...additional phases of SOCAL-15 with prey mapping are scheduled to occur in October-November 2015. By analyzing prey and predator at fine scales (100s of

  6. Solving Ratio-Dependent Predator-Prey System with Constant Effort Harvesting Using Homotopy Perturbation Method

    Directory of Open Access Journals (Sweden)

    Abdoul R. Ghotbi

    2008-01-01

    Full Text Available Due to wide range of interest in use of bioeconomic models to gain insight into the scientific management of renewable resources like fisheries and forestry, homotopy perturbation method is employed to approximate the solution of the ratio-dependent predator-prey system with constant effort prey harvesting. The results are compared with the results obtained by Adomian decomposition method. The results show that, in new model, there are less computations needed in comparison to Adomian decomposition method.

  7. Functional analysis of a specialized prey processing behavior: winnowing by surfperches (Teleostei: Embiotocidae).

    Science.gov (United States)

    Drucker, E G; Jensen, J S

    1991-12-01

    Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non-nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high-speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording. Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey-debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport. The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.

  8. Using process algebra to develop predator-prey models of within-host parasite dynamics.

    Science.gov (United States)

    McCaig, Chris; Fenton, Andy; Graham, Andrea; Shankland, Carron; Norman, Rachel

    2013-07-21

    As a first approximation of immune-mediated within-host parasite dynamics we can consider the immune response as a predator, with the parasite as its prey. In the ecological literature of predator-prey interactions there are a number of different functional responses used to describe how a predator reproduces in response to consuming prey. Until recently most of the models of the immune system that have taken a predator-prey approach have used simple mass action dynamics to capture the interaction between the immune response and the parasite. More recently Fenton and Perkins (2010) employed three of the most commonly used prey-dependent functional response terms from the ecological literature. In this paper we make use of a technique from computing science, process algebra, to develop mathematical models. The novelty of the process algebra approach is to allow stochastic models of the population (parasite and immune cells) to be developed from rules of individual cell behaviour. By using this approach in which individual cellular behaviour is captured we have derived a ratio-dependent response similar to that seen in the previous models of immune-mediated parasite dynamics, confirming that, whilst this type of term is controversial in ecological predator-prey models, it is appropriate for models of the immune system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Predator-induced flow disturbances alert prey, from the onset of an attack

    Science.gov (United States)

    Casas, Jérôme; Steinmann, Thomas

    2014-01-01

    Many prey species, from soil arthropods to fish, perceive the approach of predators, allowing them to escape just in time. Thus, prey capture is as important to predators as prey finding. We extend an existing framework for understanding the conjoint trajectories of predator and prey after encounters, by estimating the ratio of predator attack and prey danger perception distances, and apply it to wolf spiders attacking wood crickets. Disturbances to air flow upstream from running spiders, which are sensed by crickets, were assessed by computational fluid dynamics with the finite-elements method for a much simplified spider model: body size, speed and ground effect were all required to obtain a faithful representation of the aerodynamic signature of the spider, with the legs making only a minor contribution. The relationship between attack speed and the maximal distance at which the cricket can perceive the danger is parabolic; it splits the space defined by these two variables into regions differing in their values for this ratio. For this biological interaction, the ratio is no greater than one, implying immediate perception of the danger, from the onset of attack. Particular attention should be paid to the ecomechanical aspects of interactions with such small ratio, because of the high degree of bidirectional coupling of the behaviour of the two protagonists. This conclusion applies to several other predator–prey systems with sensory ecologies based on flow sensing, in air and water. PMID:25030986

  10. Age-related decline in lateralised prey capture success in Garnett's bushbaby (Otolemur garnettii).

    Science.gov (United States)

    Hanbury, David B; Edens, Kyle D; Legg, Claire E; Harrell, Shane P; Greer, Tammy F; Watson, Sheree L

    2012-01-01

    We examined differences in prey capture success when reaching for moving prey with the preferred and non-preferred hand (as determined previously using stationary food items) in 12 Garnett's bushbabies (Otolemur garnettii). Hand preference was determined by a test of simple reaching for stationary food items. We assessed both the frequency of hand use and success rates for each hand in capturing live mealworms. We also examined the effect of age on overall prey capture success. Subjects were individually presented with live mealworms in a cup partially filled with a cornmeal medium. The preferred hand was used significantly more often than the non-preferred hand to obtain the moving prey; however, no differences were found in the frequency of usage of the left vs the right hand. Furthermore, there were no differences in the success rates of the left vs the right hand, nor the preferred vs the non-preferred hand. There was a significant negative correlation between age and prey capture success. These data suggest that age, rather than preferred hand, may be the most relevant factor in the bushbabies' prey capture success.

  11. Disturbed flow in an aquatic environment may create a sensory refuge for aggregated prey

    Directory of Open Access Journals (Sweden)

    Asa Johannesen

    2017-03-01

    Full Text Available Predators use olfactory cues moved within water and air to locate prey. Because prey aggregations may produce more cue and be easier to detect, predation could limit aggregation size. However, disturbance in the flow may diminish the reliability of odour as a prey cue, impeding predator foraging success and efficiency. We explore how different cue concentrations (as a proxy for prey group size affect risk to prey by fish predators in disturbed (more turbulent or mixed and non-disturbed (less mixed flowing water. We find that increasing odour cue concentration increases predation risk and disturbing the flow reduces predation risk. At high cue concentration fish were able to locate the cue source in both disturbed and non-disturbed flow, but at medium concentrations, predators only located the cue source more often than expected by chance in non-disturbed flow. This suggests that objects disturbing flow provide a sensory refuge allowing prey to form larger groups, but that group sizes may be limited by level of disturbance to the flow.

  12. On the Gause predator-prey model with a refuge: a fresh look at the history.

    Science.gov (United States)

    Křivan, Vlastimil

    2011-04-07

    This article re-analyses a prey-predator model with a refuge introduced by one of the founders of population ecology Gause and his co-workers to explain discrepancies between their observations and predictions of the Lotka-Volterra prey-predator model. They replaced the linear functional response used by Lotka and Volterra by a saturating functional response with a discontinuity at a critical prey density. At concentrations below this critical density prey were effectively in a refuge while at a higher densities they were available to predators. Thus, their functional response was of the Holling type III. They analyzed this model and predicted existence of a limit cycle in predator-prey dynamics. In this article I show that their model is ill posed, because trajectories are not well defined. Using the Filippov method, I define and analyze solutions of the Gause model. I show that depending on parameter values, there are three possibilities: (1) trajectories converge to a limit cycle, as predicted by Gause, (2) trajectories converge to an equilibrium, or (3) the prey population escapes predator control and grows to infinity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Prey and Non-prey Arthropods Sharing a Host Plant: Effects on Induced Volatile Emission and Predator Attraction

    Science.gov (United States)

    Hordijk, Cornelis A.; Posthumus, Maarten A.; Dicke, Marcel

    2008-01-01

    It is well established that plants infested with a single herbivore species can attract specific natural enemies through the emission of herbivore-induced volatiles. However, it is less clear what happens when plants are simultaneously attacked by more than one species. We analyzed volatile emissions of lima bean and cucumber plants upon multi-species herbivory by spider mites (Tetranychus urticae) and caterpillars (Spodoptera exigua) in comparison to single-species herbivory. Upon herbivory by single or multiple species, lima bean and cucumber plants emitted volatile blends that comprised mostly the same compounds. To detect additive, synergistic, or antagonistic effects, we compared the multi-species herbivory volatile blend with the sum of the volatile blends induced by each of the herbivore species feeding alone. In lima bean, the majority of compounds were more strongly induced by multi-species herbivory than expected based on the sum of volatile emissions by each of the herbivores separately, potentially caused by synergistic effects. In contrast, in cucumber, two compounds were suppressed by multi-species herbivory, suggesting the potential for antagonistic effects. We also studied the behavioral responses of the predatory mite Phytoseiulus persimilis, a specialized natural enemy of spider mites. Olfactometer experiments showed that P. persimilis preferred volatiles induced by multi-species herbivory to volatiles induced by S. exigua alone or by prey mites alone. We conclude that both lima bean and cucumber plants effectively attract predatory mites upon multi-species herbivory, but the underlying mechanisms appear different between these species. PMID:18185960

  14. Alien Mink Predation and Colonisation Processes of Rodent Prey on Small Islands of the Baltic Sea: Does Prey Naivete Matter?

    International Nuclear Information System (INIS)

    Fey, K.; Korpimaki, E.; Banks, P.B.

    2010-01-01

    Colonisation, an important part of meta-population dynamics of fragmented populations, depends on both the dispersal ability and the ability to establish in the new habitat. Predation can hinder successful establishment of prey, and where the predation pressure comes from an alien predator, the effects on colonisation might be devastating. We studied the establishment of field voles (Microtus agrestis) inhabiting small islands of the archipelago of the Baltic Sea, SW Finland, under presence and absence of the alien American mink (Mustela vison). We translocated experienced voles from islands with mink, and inexperienced voles from islands from which mink had been removed, to other islands where mink was present or absent. By radio-tracking we studied survival, space and micro habitat use of voles within four weeks after translocation. Survival of voles on mink islands was significantly lower than on mink-free islands, but experienced voles did not survive better than inexperienced voles. Experienced voles were more often located in juniper habitats than inexperienced voles, but they appeared not to gain any survival benefit from altered micro habitat use. This study provides novel evidence, that alien mink predation inhibits establishment of colonising field voles and may thus ultimately induce extinction of voles from the outer archipelago.

  15. A Generalist Protist Predator Enables Coexistence in Multitrophic Predator-Prey Systems Containing a Phage and the Bacterial Predator Bdellovibrio

    Directory of Open Access Journals (Sweden)

    Julia Johnke

    2017-10-01

    Full Text Available Complex ecosystems harbor multiple predators and prey species whose direct and indirect interactions are under study. In particular, the combined effects of predator diversity and resource preference on prey removal are not known. To understand the effect of interspecies interactions, combinations of micro-predators—i.e., protists (generalists, predatory bacteria (semi-specialists, and phages (specialists—and bacterial prey were tracked over a 72-h period in miniature membrane bioreactors. While specialist predators alone drove their preferred prey to extinction, the inclusion of a generalist resulted in uniform losses among prey species. Most importantly, presence of a generalist predator enabled coexistence of all predators and prey. As the generalist predator also negatively affected the other predators, we suggest that resource partitioning between predators and the constant availability of resources for bacterial growth due to protist predation stabilizes the system and keeps its diversity high. The appearance of resistant prey strains and subsequent evolution of specialist predators unable to infect the ancestral prey implies that multitrophic communities are able to persist and stabilize themselves. Interestingly, the appearance of BALOs and phages unable to infect their prey was only observed for the BALO or phage in the absence of additional predators or prey species indicating that competition between predators might influence coevolutionary dynamics.

  16. Border Terriers under primary veterinary care in England: demography and disorders.

    Science.gov (United States)

    O'Neill, Dan G; Darwent, Elisabeth C; Church, David B; Brodbelt, Dave C

    2017-01-01

    The Border Terrier is a working terrier type that is generally considered to be a relatively healthy and hardy breed. This study aimed to characterise the demography and common disorders of Border Terriers receiving veterinary care in England using de-identified electronic patient record data within the VetCompass™ Programme. Annual birth proportion for Border Terriers showed a decreasing trend from 1.46% in 2005 to 0.78% in 2014. The median adult bodyweight for males (10.9 kg, IQR: 9.6-12.3, range: 6.3-25.0) was higher than for females (9.1 kg, IQR: 8.2-10.3, range: 5.2-21.6) ( P  skin disorder (10.17%, 95% CI: 8.60-11.93).Syndromic analysis showed that the most prevalent body locations affected were the head-and-neck (37.75%, 95% CI: 35.14-40.43), abdomen (18.61%, 95% CI: 16.55-20.81) and limb (11.53%, 95% CI: 9.86-13.37). At least one organ system was affected in 834 (62.85%) Border Terriers. The most prevalent organ systems affected were the digestive (32.03%, 95% CI: 29.52-34.61), integument (26.68%, 95% CI: 24.31-29.14), connective/soft tissue (11.15%, 95% CI: 9.51-12.97) and auditory (9.87%, 95% CI: 8.32-11.60). At least one affected pathophysiological process was described in 881 (66.39%) Border Terriers. The most prevalent pathophysiologic processes recorded were inflammation (31.65%, 95% CI: 29.15-34.23), nutritional (9.04%, 95% CI: 7.55-10.72), mass/swelling (8.89%, 95% CI: 7.42-10.55), traumatic (7.99%, 95% CI: 6.59-9.58) and infectious (7.76%, 95% CI: 6.38-9.33). This study documented a trend towards reducing ownership and relatively long-livedness in the Border Terrier. The most common disorders were periodontal disease, overweight/obesity and otitis externa. Predisposition to dental and neurological disease was suggested. These results can provide a comprehensive evidence resource to support breed-based health plans that can contribute positively to reforms to improve health and welfare within the breed.

  17. Comparative demography of two common scleractinian corals: Orbicella annularis and Porites astreoides

    Directory of Open Access Journals (Sweden)

    Francisco J. Soto-Santiago

    2017-10-01

    Full Text Available Background Studies directed at understanding the demography and population dynamics of corals are relatively scarce. This limits our understanding of both the dynamics of coral populations and our capacity to develop management and conservation initiatives directed at conserving such ecosystems. Methods From 2012 to 2014, we collected data on the growth, survival, and recruitment rates of two common Caribbean coral species, the stress-tolerant Orbicella annularis and the weedy Porites astreoides. A set of size-based population matrix model was developed for two localities in Northeastern Puerto Rico and used to estimate population growth rates (λ and determine the life cycle transition(s that contribute the most to spatiotemporal differences in λs. The model was parameterized by following the fate of 100 colonies of each species at the two sites for two years. Results Our data indicate that spatial variability in vital rates of both species was higher than temporal variability. During the first year, populations of O. annularis exhibited λs below equilibrium at Carlos Rosario (0.817 and Palomino (0.694, followed by a considerable decline at both sites during the second year (0.700 and 0.667. Populations of P. astreoides showed higher λs than O. annularis during the first census period at Carlos Rosario (0.898 and Palomino (0.894 with a decline at one of the sites (0.681 and 0.893 during the second census period. Colony fate in both species exhibited a significant interaction with respect to location but not to time (G2 = 20.96; df = 3 for O. annularis and G2 = 9.55; df = 3 for P. astreoides. Discussion The similar variability of λs as well as the similar survival rates for both species during the two-year census period (2012–2014 show similar variability on demographic patterns in space and time. Our results suggest that location rather than time is important for the resiliency in coral colonies. Also, P. astreoides will show higher

  18. Sea urchins, their predators and prey in SW Portugal

    Directory of Open Access Journals (Sweden)

    Nuno Mamede

    2014-06-01

    Full Text Available Sea urchins play a key role structuring benthic communities of rocky shores through an intense herbivory. The most abundant sea urchin species on shallow rocky subtidal habitats of the SW coast of Portugal is Paracentrotus lividus (Echinodermata: Echinoidea. It is considered a key species in various locations throughout its geographical distribution by affecting the structure of macroalgae communities and may cause the abrupt transformation of habitats dominated by foliose algae to habitats dominated by encrusting algae - the urchin barrens. The removal of P. lividus predators by recreational and commercial fishing is considered a major cause of this phenomenon by affecting the trophic relationships between predators, sea urchins and algae communities. Marine protected areas (MPAs usually lead to the recovery of important predator species that control sea urchin populations and restore habitats dominated by foliose macroalgae. Therefore, MPAs provide a good opportunity to test cascading effects and indirect impacts of fishing at the ecosystem level. The ecological role of P. lividus was studied on rocky subtidal habitats of the SW coast of Portugal (Alentejo considering three trophic levels: population of P. lividus, their predators (fish and shellfish and their prey (macroalgae communities. Several studies were conducted: (1 a non-destructive observational study on the abundance and distribution patterns of P. lividus, their predators and preys, comparing areas with different protection; (2 a manipulative in situ study with cages to assess the role of P. lividus as an herbivore and the influence of predation; (3 a descriptive study of P. lividus predators based on underwater filming; (4 and a study of human perception on these trophic relationships and other issues on sea urchin ecology and fishery, based on surveys made to fishermen and divers. Subtidal studies were performed with SCUBA diving at 3-12 m deep. Results indicate that in the

  19. Effectiveness of community forestry in Prey Long forest, Cambodia.

    Science.gov (United States)

    Lambrick, Frances H; Brown, Nick D; Lawrence, Anna; Bebber, Daniel P

    2014-04-01

    Cambodia has 57% forest cover, the second highest in the Greater Mekong region, and a high deforestation rate (1.2%/year, 2005-2010). Community forestry (CF) has been proposed as a way to reduce deforestation and support livelihoods through local management of forests. CF is expanding rapidly in Cambodia. The National Forests Program aims to designate one million hectares of forest to CF by 2030. However, the effectiveness of CF in conservation is not clear due to a global lack of controlled comparisons, multiple meanings of CF, and the context-specific nature of CF implementation. We assessed the effectiveness of CF by comparing 9 CF sites with paired controls in state production forest in the area of Prey Long forest, Cambodia. We assessed forest condition in 18-20 randomly placed variable-radius plots and fixed-area regeneration plots. We surveyed 10% of households in each of the 9 CF villages to determine the proportion that used forest products, as a measure of household dependence on the forest. CF sites had fewer signs of anthropogenic damage (cut stems, stumps, and burned trees), higher aboveground biomass, more regenerating stems, and reduced canopy openness than control areas. Abundance of economically valuable species, however, was higher in control sites. We used survey results and geographic parameters to model factors affecting CF outcomes. Interaction between management type, CF or control, and forest dependence indicated that CF was more effective in cases where the community relied on forest products for subsistence use and income. © 2014 Society for Conservation Biology.

  20. Are owl pellets good estimators of prey abundance?

    Directory of Open Access Journals (Sweden)

    Analia Andrade

    2016-07-01

    Full Text Available Some ecologists have been skeptics about the use of owl pellets to estimate small mammal’s fauna. This is due to the assumptions required by this method: (a that owls hunt at random, and (b that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal’s species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal’s abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.

  1. Effects of prey abundance, distribution, visual contrast and morphology on selection by a pelagic piscivore

    Science.gov (United States)

    Hansen, Adam G.; Beauchamp, David A.

    2014-01-01

    Most predators eat only a subset of possible prey. However, studies evaluating diet selection rarely measure prey availability in a manner that accounts for temporal–spatial overlap with predators, the sensory mechanisms employed to detect prey, and constraints on prey capture.We evaluated the diet selection of cutthroat trout (Oncorhynchus clarkii) feeding on a diverse planktivore assemblage in Lake Washington to test the hypothesis that the diet selection of piscivores would reflect random (opportunistic) as opposed to non-random (targeted) feeding, after accounting for predator–prey overlap, visual detection and capture constraints.Diets of cutthroat trout were sampled in autumn 2005, when the abundance of transparent, age-0 longfin smelt (Spirinchus thaleichthys) was low, and 2006, when the abundance of smelt was nearly seven times higher. Diet selection was evaluated separately using depth-integrated and depth-specific (accounted for predator–prey overlap) prey abundance. The abundance of different prey was then adjusted for differences in detectability and vulnerability to predation to see whether these factors could explain diet selection.In 2005, cutthroat trout fed non-randomly by selecting against the smaller, transparent age-0 longfin smelt, but for the larger age-1 longfin smelt. After adjusting prey abundance for visual detection and capture, cutthroat trout fed randomly. In 2006, depth-integrated and depth-specific abundance explained the diets of cutthroat trout well, indicating random feeding. Feeding became non-random after adjusting for visual detection and capture. Cutthroat trout selected strongly for age-0 longfin smelt, but against similar sized threespine stickleback (Gasterosteus aculeatus) and larger age-1 longfin smelt in 2006. Overlap with juvenile sockeye salmon (O. nerka) was minimal in both years, and sockeye salmon were rare in the diets of cutthroat trout.The direction of the shift between random and non-random selection

  2. The genetical theory of social behaviour.

    Science.gov (United States)

    Lehmann, Laurent; Rousset, François

    2014-05-19

    We survey the population genetic basis of social evolution, using a logically consistent set of arguments to cover a wide range of biological scenarios. We start by reconsidering Hamilton's (Hamilton 1964 J. Theoret. Biol. 7, 1-16 (doi:10.1016/0022-5193(64)90038-4)) results for selection on a social trait under the assumptions of additive gene action, weak selection and constant environment and demography. This yields a prediction for the direction of allele frequency change in terms of phenotypic costs and benefits and genealogical concepts of relatedness, which holds for any frequency of the trait in the population, and provides the foundation for further developments and extensions. We then allow for any type of gene interaction within and between individuals, strong selection and fluctuating environments and demography, which may depend on the evolving trait itself. We reach three conclusions pertaining to selection on social behaviours under broad conditions. (i) Selection can be understood by focusing on a one-generation change in mean allele frequency, a computation which underpins the utility of reproductive value weights; (ii) in large populations under the assumptions of additive gene action and weak selection, this change is of constant sign for any allele frequency and is predicted by a phenotypic selection gradient; (iii) under the assumptions of trait substitution sequences, such phenotypic selection gradients suffice to characterize long-term multi-dimensional stochastic evolution, with almost no knowledge about the genetic details underlying the coevolving traits. Having such simple results about the effect of selection regardless of population structure and type of social interactions can help to delineate the common features of distinct biological processes. Finally, we clarify some persistent divergences within social evolution theory, with respect to exactness, synergies, maximization, dynamic sufficiency and the role of genetic arguments.

  3. Socio-demography and medical history as predictors of health-related quality of life of breast cancer survivors.

    Science.gov (United States)

    Ramadas, Amutha; Qureshi, Ahmad Munir; Dominic, Nisha Angela; Botross, Nevein Philip; Riad, Amgad; Thirunavuk Arasoo, Valliammai Jayanthi; Elangovan, Soman

    2015-01-01

    Even after completion of conventional treatment, breast cancer survivors continue to exhibit a variety of psychological and physical symptoms, affecting their quality of life. The study aimed to investigate the relationship between socio-demography, medical characteristics and health-related quality of life (HR-QOL) of a sample of breast cancer survivors in Malaysia. This pilot cross-sectional survey was conducted among breast cancer survivors (n=40) who were members of Breast Cancer Support Group Centre Johor Bahru. A validated self-administered questionnaire was used to identify the relationships between socio-demography, medical characteristics and HR-QOL of the participants. Living with family and completion of treatment were significant predictive factors of self-rated QOL, while living with family and ever giving birth significantly predicted satisfaction with health and physical health. Psychological health had moderate correlations with number of children and early cancer stage. Survivors' higher personal income (>MYR4,500) was the only significant predictor of social relationship, while age, income more than MYR4,500 and giving birth significantly predicted environment domain score. The findings suggested the survivors coped better in all four HR-QOL domains if they were married, lived with family, had children and were employed.

  4. Growth and demography of the solitary scleractinian coral Leptopsammia pruvoti along a sea surface temperature gradient in the Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Erik Caroselli

    Full Text Available The demographic traits of the solitary azooxanthellate scleractinian Leptopsammia pruvoti were determined in six populations on a sea surface temperature (SST gradient along the western Italian coasts. This is the first investigation of the growth and demography characteristics of an azooxanthellate scleractinian along a natural SST gradient. Growth rate was homogeneous across all populations, which spanned 7 degrees of latitude. Population age structures differed between populations, but none of the considered demographic parameters correlated with SST, indicating possible effects of local environmental conditions. Compared to another Mediterranean solitary scleractinian, Balanophyllia europaea, zooxanthellate and whose growth, demography and calcification have been studied in the same sites, L. pruvoti seems more tolerant to temperature increase. The higher tolerance of L. pruvoti, relative to B. europaea, may rely on the absence of symbionts, and thus the lack of an inhibition of host physiological processes by the heat-stressed zooxanthellae. However, the comparison between the two species must be taken cautiously, due to the likely temperature differences between the two sampling depths. Increasing research effort on determining the effects of temperature on the poorly studied azooxanthellate scleractinians may shed light on the possible species assemblage shifts that are likely to occur during the current century as a consequence of global climatic change.

  5. Spatial structure and nest demography reveal the influence of competition, parasitism and habitat quality on slavemaking ants and their hosts.

    Science.gov (United States)

    Scharf, Inon; Fischer-Blass, Birgit; Foitzik, Susanne

    2011-03-28

    Natural communities are structured by intra-guild competition, predation or parasitism and the abiotic environment. We studied the relative importance of these factors in two host-social parasite ecosystems in three ant communities in Europe (Bavaria) and North America (New York, West Virginia). We tested how these factors affect colony demography, life-history and the spatial pattern of colonies, using a large sample size of more than 1000 colonies. The strength of competition was measured by the distance to the nearest competitor. Distance to the closest social parasite colony was used as a measure of parasitism risk. Nest sites (i.e., sticks or acorns) are limited in these forest ecosystems and we therefore included nest site quality as an abiotic factor in the analysis. In contrast to previous studies based on local densities, we focus here on the positioning and spatial patterns and we use models to compare our predictions to random expectations. Colony demography was universally affected by the size of the nest site with larger and more productive colonies residing in larger nest sites of higher quality. Distance to the nearest competitor negatively influenced host demography and brood production in the Bavarian community, pointing to an important role of competition, while social parasitism was less influential in this community. The New York community was characterized by the highest habitat variability, and productive colonies were clustered in sites of higher quality. Colonies were clumped on finer spatial scales, when we considered only the nearest neighbors, but more regularly distributed on coarser scales. The analysis of spatial positioning within plots often produced different results compared to those based on colony densities. For example, while host and slavemaker densities are often positively correlated, slavemakers do not nest closer to potential host colonies than expected by random. The three communities are differently affected by biotic and

  6. Spatial structure and nest demography reveal the influence of competition, parasitism and habitat quality on slavemaking ants and their hosts

    Directory of Open Access Journals (Sweden)

    Fischer-Blass Birgit

    2011-03-01

    Full Text Available Abstract Background Natural communities are structured by intra-guild competition, predation or parasitism and the abiotic environment. We studied the relative importance of these factors in two host-social parasite ecosystems in three ant communities in Europe (Bavaria and North America (New York, West Virginia. We tested how these factors affect colony demography, life-history and the spatial pattern of colonies, using a large sample size of more than 1000 colonies. The strength of competition was measured by the distance to the nearest competitor. Distance to the closest social parasite colony was used as a measure of parasitism risk. Nest sites (i.e., sticks or acorns are limited in these forest ecosystems and we therefore included nest site quality as an abiotic factor in the analysis. In contrast to previous studies based on local densities, we focus here on the positioning and spatial patterns and we use models to compare our predictions to random expectations. Results Colony demography was universally affected by the size of the nest site with larger and more productive colonies residing in larger nest sites of higher quality. Distance to the nearest competitor negatively influenced host demography and brood production in the Bavarian community, pointing to an important role of competition, while social parasitism was less influential in this community. The New York community was characterized by the highest habitat variability, and productive colonies were clustered in sites of higher quality. Colonies were clumped on finer spatial scales, when we considered only the nearest neighbors, but more regularly distributed on coarser scales. The analysis of spatial positioning within plots often produced different results compared to those based on colony densities. For example, while host and slavemaker densities are often positively correlated, slavemakers do not nest closer to potential host colonies than expected by random. Conclusions The

  7. A longitudinal cline characterizes the genetic structure of human populations in the Tibetan plateau

    Science.gov (United States)

    Peter, Benjamin M.; Basnyat, Buddha; Neupane, Maniraj; Beall, Cynthia M.; Childs, Geoff; Craig, Sienna R.; Novembre, John; Di Rienzo, Anna

    2017-01-01

    Indigenous populations of the Tibetan plateau have attracted much attention for their good performance at extreme high altitude. Most genetic studies of Tibetan adaptations have used genetic variation data at the genome scale, while genetic inferences about their demography and population structure are largely based on uniparental markers. To provide genome-wide information on population structure, we analyzed new and published data of 338 individuals from indigenous populations across the plateau in conjunction with worldwide genetic variation data. We found a clear signal of genetic stratification across the east-west axis within Tibetan samples. Samples from more eastern locations tend to have higher genetic affinity with lowland East Asians, which can be explained by more gene flow from lowland East Asia onto the plateau. Our findings corroborate a previous report of admixture signals in Tibetans, which were based on a subset of the samples analyzed here, but add evidence for isolation by distance in a broader geospatial context. PMID:28448508

  8. Foraging mechanisms of siscowet lake trout (Salvelinus namaycush siscowet) on pelagic prey

    Science.gov (United States)

    Keyler, Trevor D.; Hrabik, Thomas R.; Austin, C. Lee; Gorman, Owen T.; Mensinger, Allen F.

    2015-01-01

    The reaction distance, angle of attack, and foraging success were determined for siscowet lake trout (Salvelinus namaycush siscowet) during laboratory trials under lighting conditions that approximated downwelling spectral irradiance and intensity (9.00 × 108–1.06 × 1014 photons m− 2 s− 1) at daytime depths. Siscowet reaction distance in response to golden shiners (Notemigonus crysoleucas) was directly correlated with increasing light intensity until saturation at 1.86 × 1011 photons m− 2 s− 1, above which reaction distance was constant within the range of tested light intensities. At the lowest tested light intensity, sensory detection was sufficient to locate prey at 25 ± 2 cm, while increasing light intensities increased reaction distance up to 59 ± 2 cm at 1.06 × 1014 photons m− 2 s− 1. Larger prey elicited higher reaction distances than smaller prey at all light intensities while moving prey elicited higher reaction distances than stationary prey at the higher light intensities (6.00 × 109 to 1.06 × 1014 photons m− 2 s− 1). The capture and consumption of prey similarly increased with increasing light intensity while time to capture decreased with increasing light intensity. The majority of orientations toward prey occurred within 120° of the longitudinal axis of the siscowet's eyes, although reaction distances among 30° increments along the entire axis were not significantly different. The developed predictive model will help determine reaction distances for siscowet in various photic environments and will help identify the mechanisms and behavior that allow for low light intensity foraging within freshwater systems.

  9. Responses to river inundation pressures control prey selection of riparian beetles.

    Directory of Open Access Journals (Sweden)

    Matt J O'Callaghan

    Full Text Available Riparian habitats are subjected to frequent inundation (flooding and are characterised by food webs that exhibit variability in aquatic/terrestrial subsidies across the ecotone. The strength of this subsidy in active riparian floodplains is thought to underpin local biodiversity. Terrestrial invertebrates dominate the fauna, exhibiting traits that allow exploitation of variable aquatic subsidies while reducing inundation pressures, leading to inter-species micro-spatial positioning. The effect these strategies have on prey selection is not known. This study hypothesised that plasticity in prey choice from either aquatic or terrestrial sources is an important trait linked to inundation tolerance and avoidance.We used hydrological, isotopic and habitat analyses to investigate the diet of riparian Coleoptera in relation to inundation risk and relative spatial positioning in the floodplain. The study examined patch scale and longitudinal changes in utilisation of the aquatic subsidy according to species traits. Prey sourced from terrestrial or emerging/stranded aquatic invertebrates varied in relation to traits for inundation avoidance or tolerance strategies. Traits that favoured rapid dispersal corresponded with highest proportions of aquatic prey, with behavioural traits further predicting uptake. Less able dispersers showed minimal use of aquatic subsidy and switched to a terrestrial diet under moderate inundation pressures. All trait groups showed a seasonal shift in diet towards terrestrial prey in the early spring. Prey selection became exaggerated towards aquatic prey in downstream samples.Our results suggest that partitioning of resources and habitat creates overlapping niches that increase the processing of external subsidies in riparian habitats. By demonstrating functional complexity, this work advances understanding of floodplain ecosystem processes and highlights the importance of hydrological variability. With an increasing interest

  10. Prey capture kinematics and four-bar linkages in the bay pipefish, Syngnathus leptorhynchus.

    Science.gov (United States)

    Flammang, Brooke E; Ferry-Graham, Lara A; Rinewalt, Christopher; Ardizzone, Daniele; Davis, Chante; Trejo, Tonatiuh

    2009-01-01

    Because of their modified cranial morphology, syngnathid pipefishes have been described as extreme suction feeders. The presumption is that these fishes use their elongate snout much like a pipette in capturing planktonic prey. In this study, we quantify the contribution of suction to the feeding strike and quantitatively describe the prey capture mechanics of the bay pipefish Syngnathus leptorhynchus, focusing specifically on the role of both cranial elevation and snout movement. We used high-speed video to capture feeding sequences from nine individuals feeding on live brine shrimp. Sequences were digitized in order to calculate kinematic variables that could be used to describe prey capture. Prey capture was very rapid, from 2 to 6 ms from the onset of cranial rotation. We found that suction contributed at most about one-eighth as much as ram to the reduction of the distance between predator and prey. This movement of the predator was due almost exclusively to movement of the snout and neurocranium rather than movement of the whole body. The body was positioned ventral and posterior to the prey and the snout was rotated dorsally by as much as 21 degrees, thereby placing the mouth immediately behind the prey for capture. The snout did not follow the identical trajectory as the neurocranium, however, and reached a maximum angle of only about 10 degrees. The snout consists, in part, of elongate suspensorial elements and the linkages among these elements are retained despite changes in shape. Thus, when the neurocranium is rotated, the four-bar linkage that connects this action with hyoid depression simultaneously acts to expand and straighten the snout relative to the neurocranium. We confirm the presence of a four-bar linkage that facilitates these kinematics by couplings between the pectoral girdle, urohyal, hyoid complex, and the neurocranium-suspensorium complex.

  11. Assessing breeding potential of peregrine falcons based on chlorinated hydrocarbon concentrations in prey

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, J.E. [Canadian Wildlife Service, Pacific Wildlife Research Centre, 5421 Robertson Rd., RR no. 1, Delta, British Columbia, V4K 3N2 (Canada)]. E-mail: john.elliott@ec.gc.ca; Miller, M.J. [Iolaire Ecological Consulting, 7899 Thrasher St., Mission, British Columbia, V2V 5H3 (Canada); Wilson, L.K. [Canadian Wildlife Service, Pacific Wildlife Research Centre, 5421 Robertson Rd., RR no. 1, Delta, British Columbia, V4K 3N2 (Canada)

    2005-03-01

    Peregrine falcons (Falco peregrinus) now breed successfully in most areas of North America from which they were previously extirpated. The loss during the mid-part of the last century of many of the world's peregrine populations was largely a consequence of impaired reproduction caused by the effects of DDE on eggshell quality and embryo hatchability. Population recovery has been attributed to re-introduction efforts, coupled with regulatory restrictions on the use of organochlorine pesticides. Peregrines have not returned to breed in some areas, such as the Okanagan Valley of British Columbia. That region has been extensively planted in fruit orchards which were treated annually with DDT during the early 1950s to the 1970s. Ongoing contamination of avian species, including potential peregrine prey, inhabiting orchards has been documented. In response to an initiative to release peregrines around the city of Kelowna in the Okanagan Valley, we collected potential peregrine prey species and analyzed whole bodies for chlorinated hydrocarbon residues. We used a simple bioaccumulation model to predict concentrations of DDE in peregrine eggs using concentrations in prey and estimates of dietary makeup as input. Peregrines would be expected to breed successfully only if they fed on a diet primarily of doves. Feeding on as little as 10% of other species such as starlings, robins, gulls and magpies would produce DDE concentrations in peregrine eggs greater than the threshold of 15 mg/kg. We also estimated the critical concentration of DDE in total prey to be about 0.5 mg/kg, one half of the previous most conservative criterion for peregrine prey. Concentrations of dieldrin and PCBs in peregrine prey are less than suggested critical levels. - Based on the level of DDE contamination of prey items, it seems unlikely that peregrine falcons could breed successfully throughout most of the Okanagan Valley of British Columbia.

  12. Modelling landscape-level numerical responses of predators to prey: the case of cats and rabbits.

    Directory of Open Access Journals (Sweden)

    Jennyffer Cruz

    Full Text Available Predator-prey systems can extend over large geographical areas but empirical modelling of predator-prey dynamics has been largely limited to localised scales. This is due partly to difficulties in estimating predator and prey abundances over large areas. Collection of data at suitably large scales has been a major problem in previous studies of European rabbits (Oryctolagus cuniculus and their predators. This applies in Western Europe, where conserving rabbits and predators such as Iberian lynx (Lynx pardinus is important, and in other parts of the world where rabbits are an invasive species supporting populations of introduced, and sometimes native, predators. In pastoral regions of New Zealand, rabbits are the primary prey of feral cats (Felis catus that threaten native fauna. We estimate the seasonal numerical response of cats to fluctuations in rabbit numbers in grassland-shrubland habitat across the Otago and Mackenzie regions of the South Island of New Zealand. We use spotlight counts over 1645 km of transects to estimate rabbit and cat abundances with a novel modelling approach that accounts simultaneously for environmental stochasticity, density dependence and varying detection probability. Our model suggests that cat abundance is related consistently to rabbit abundance in spring and summer, possibly through increased rabbit numbers improving the fecundity and juvenile survival of cats. Maintaining rabbits at low abundance should therefore suppress cat numbers, relieving predation pressure on native prey. Our approach provided estimates of the abundance of cats and rabbits over a large geographical area. This was made possible by repeated sampling within each season, which allows estimation of detection probabilities. A similar approach could be applied to predator-prey systems elsewhere, and could be adapted to any method of direct observation in which there is no double-counting of individuals. Reliable estimates of numerical

  13. Ultrasonic predator-prey interactions in water-convergent evolution with insects and bats in air?

    Science.gov (United States)

    Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

    2013-01-01

    Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

  14. Ultrasonic predator-prey interactions in water– convergent evolution with insects and bats in air?

    Directory of Open Access Journals (Sweden)

    Maria eWilson

    2013-06-01

    Full Text Available Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden. These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them.Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments however, show that neither fish with swim bladder, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

  15. Are single odorous components of a predator sufficient to elicit defensive behaviors in prey species?

    Directory of Open Access Journals (Sweden)

    Raimund eApfelbach

    2015-07-01

    Full Text Available When exposed to the odor of a sympatric predator, prey animals typically display escape or defensive responses. These phenomena have been well-documented, especially in rodents, when exposed to the odor of a cat, ferret or fox. As a result of these experiments new discussions center on the following questions: 1 is a single volatile compound such as a major or a minor mixture constituent in urine or feces, emitted by the predator sufficient to cause defensive reactions in a potential prey species or 2 is a whole array of odors required to elicit a response and 3 will the relative size or escapability of the prey as compared to the predator influence responsiveness. Most predator-prey studies on this topic have been performed in the laboratory or under semi-natural conditions. Field studies could help to find answers to these questions. Australian mammals are completely naïve towards the introduced placental carnivores. That offers ideal opportunities to analyze in the field the responses of potential prey species to unknown predator odors. During the last decades researchers have accumulated an enormous amount of data exploring the effects of eutherian predator odors on native marsupial mammals. In this review, we will give a survey about the development of olfactory research, chemical signals and their influence on the behavior and - in some cases - physiology of prey species. In addition, we report on the effects of predator odor experiments performed under natural conditions in Australia. When studying all these literature we learned that data gained under controlled laboratory conditions elucidate the role of individual odors on brain structures and ultimately on a comparatively narrow range behaviors. In contrast to single odors odor arrays mimic much more the situation prey animals are confronted to in nature. Therefore, a broad range of methodology — from chemistry to ecology including anatomy, physiology and behavior — is needed to

  16. Changes in Alaskan soft-bottom prey communities along a gradient in sea otter predation

    Science.gov (United States)

    Kvitek, R.G.; Oliver, J.S.; DeGange, A.R.; Anderson, B.S.

    1992-01-01

    Sea Otter (Enhydra lutris), well documented as "keystone" predators in rocky marine communities, were found to exert a strong influence on infaunal prey communities in soft-sediment habitats. Direct and indirect effects of sea otter predation on subtidal soft-bottom prey communities were evaluated along a temporal gradient of sea otter occupancy around the Kodiak Archipelago. The results indicate that Kodiak otters forage primarily on bivalve prey and dramatically reduce infaunal bivalve and green sea urchin (Strongylocentrotus droebachiensis) prey populations. Bivalve prey abundance, biomass, and size were inversely related to duration of sea otter occupancy. The relative conditions of shells discarded by otters in shallow ( 20 m) water at the same sites indicate that otters first exploited Saxidomus in shallow-water feeding areas, and later switched to Macoma spp. in deeper water. Otter-cracked shells of the deep-burrowing clam Tresus capax were rarely found, even at otter foraging sites where the clam accounted for the majority of available prey biomass, suggesting that it has a partial depth refuge from otter predation. The indirect effects of otter predation included substratum disturbance and the facilitation of sea star predation on infaunal prey. Sea stars, Pycnopodia helianthoides, were attracted to experimentally dug excavations as well as natural sea otter foraging pits, where the sea stars foraged on smaller size classes of infaunal bivalves than those eaten by otters. Otters also discard clam shells on the sediment surface and expose old, buried shells during excavation. Surface shells were found to provide attachment sites for large anemones and kelp. Our study shows that sea otters can affect soft-sediment communities, not only through predation, as in rocky habitats, but also through disturbance, and thus retain a high degree of influence in two very different habitat types.

  17. Predation on exotic zebra mussels by native fishes: Effects on predator and prey

    Science.gov (United States)

    Magoulick, D.D.; Lewis, L.C.

    2002-01-01

    1. Exotic zebra mussels, Dreissena polymorpha, occur in southern U.S. waterways in high densities, but little is known about the interaction between native fish predators and zebra mussels. Previous studies have suggested that exotic zebra mussels are low profitability prey items and native vertebrate predators are unlikely to reduce zebra mussel densities. We tested these hypotheses by observing prey use of fishes, determining energy content of primary prey species of fishes, and conducting predator exclusion experiments in Lake Dardanelle, Arkansas. 2. Zebra mussels were the primary prey eaten by 52.9% of blue catfish, Ictalurus furcatus; 48.2% of freshwater drum, Aplodinotus grunniens; and 100% of adult redear sunfish, Lepomis microlophus. Blue catfish showed distinct seasonal prey shifts, feeding on zebra mussels in summer and shad, Dorosoma spp., during winter. Energy content (joules g-1) of blue catfish prey (threadfin shad, Dorosoma petenense; gizzard shad, D. cepedianum; zebra mussels; and asiatic clams, Corbicula fluminea) showed a significant species by season interaction, but shad were always significantly greater in energy content than bivalves examined as either ash-free dry mass or whole organism dry mass. Fish predators significantly reduced densities of large zebra mussels (>5 mm length) colonising clay tiles in the summers of 1997 and 1998, but predation effects on small zebra mussels (???5 mm length) were less clear. 3. Freshwater drum and redear sunfish process bivalve prey by crushing shells and obtain low amounts of higher-energy food (only the flesh), whereas blue catfish lack a shell-crushing apparatus and ingest large amounts of low-energy food per unit time (bivalves with their shells). Blue catfish appeared to select the abundant zebra mussel over the more energetically rich shad during summer, then shifted to shad during winter when shad experienced temperature-dependent stress and mortality. Native fish predators can suppress adult zebra

  18. Management intensity and vegetation complexity affect web-building spiders and their prey.

    Science.gov (United States)

    Diehl, Eva; Mader, Viktoria L; Wolters, Volkmar; Birkhofer, Klaus

    2013-10-01

    Agricultural management and vegetation complexity affect arthropod diversity and may alter trophic interactions between predators and their prey. Web-building spiders are abundant generalist predators and important natural enemies of pests. We analyzed how management intensity (tillage, cutting of the vegetation, grazing by cattle, and synthetic and organic inputs) and vegetation complexity (plant species richness, vegetation height, coverage, and density) affect rarefied richness and composition of web-building spiders and their prey with respect to prey availability and aphid predation in 12 habitats, ranging from an uncut fallow to a conventionally managed maize field. Spiders and prey from webs were collected manually and the potential prey were quantified using sticky traps. The species richness of web-building spiders and the order richness of prey increased with plant diversity and vegetation coverage. Prey order richness was lower at tilled compared to no-till sites. Hemipterans (primarily aphids) were overrepresented, while dipterans, hymenopterans, and thysanopterans were underrepresented in webs compared to sticky traps. The per spider capture efficiency for aphids was higher at tilled than at no-till sites and decreased with vegetation complexity. After accounting for local densities, 1.8 times more aphids were captured at uncut compared to cut sites. Our results emphasize the functional role of web-building spiders in aphid predation, but suggest negative effects of cutting or harvesting. We conclude that reduced management intensity and increased vegetation complexity help to conserve local invertebrate diversity, and that web-building spiders at sites under low management intensity (e.g., semi-natural habitats) contribute to aphid suppression at the landscape scale.

  19. Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

    Science.gov (United States)

    Manríquez, Patricio H.; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M.; Torres, Rodrigo; Lardies, Marcos A.; Vargas, Cristian A.; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A.

    2013-01-01

    Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature. PMID:23844231

  20. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco.

    Directory of Open Access Journals (Sweden)

    Patricio H Manríquez

    Full Text Available BACKGROUND: Most research on Ocean Acidification (OA has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. METHODOLOGY/PRINCIPAL FINDINGS: The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE (716 ± 12 and 1036 ± 14 µatm CO2 compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2. When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. CONCLUSIONS AND SIGNIFICANCE: These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  1. Ocean acidification disrupts prey responses to predator cues but not net prey shell growth in Concholepas concholepas (loco).

    Science.gov (United States)

    Manríquez, Patricio H; Jara, María Elisa; Mardones, María Loreto; Navarro, Jorge M; Torres, Rodrigo; Lardies, Marcos A; Vargas, Cristian A; Duarte, Cristian; Widdicombe, Stephen; Salisbury, Joseph; Lagos, Nelson A

    2013-01-01

    Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716 ± 12 and 1036 ± 14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388 ± 8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

  2. Kelp Forests versus Urchin Barrens: Alternate Stable States and Their Effect on Sea Otter Prey Quality in the Aleutian Islands

    Directory of Open Access Journals (Sweden)

    Nathan L. Stewart

    2012-01-01

    Full Text Available Macroalgal and urchin barren communities are alternately stable and persist in the Aleutians due to sea otter presence and absence. In the early 1990s a rapid otter population decline released urchins from predation and caused a shift to the urchin-dominated state. Despite increases in urchin abundance, otter numbers continued to decline. Although debated, prey quality changes have been implicated in current otter population status. This study examined otter prey abundance, size, biomass, and potential energy density in remnant kelp forest and urchin-dominated communities to determine if alternate stable states affect prey quality. Findings suggest that although urchin barrens provide more abundant urchin prey, individual urchins are smaller and provide lower biomass and potential energy density compared to kelp forests. Shifts to urchin barrens do affect prey quality but changes are likely compensated by increased prey densities and are insufficient in explaining current otter population status in the Aleutians.

  3. Feeding with speed: prey capture evolution in cichlids

    Czech Academy of Sciences Publication Activity Database

    Higham, T. E.; Hulsey, C. D.; Říčan, Oldřich; Carroll, A. M.

    2007-01-01

    Roč. 20, - (2007), s. 70-78 ISSN 1010-061X Grant - others:GA JU(CZ) 04_GAJU-58 Institutional research plan: CEZ:AV0Z50450515 Keywords : Cichlidae * comparative methods * ecomorphology Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.920, year: 2007

  4. Genetic algorithms

    Science.gov (United States)

    Wang, Lui; Bayer, Steven E.

    1991-01-01

    Genetic algorithms are mathematical, highly parallel, adaptive search procedures (i.e., problem solving methods) based loosely on the processes of natural genetics and Darwinian survival of the fittest. Basic genetic algorithms concepts are introduced, genetic algorithm applications are introduced, and results are presented from a project to develop a software tool that will enable the widespread use of genetic algorithm technology.

  5. The diets of Hispaniolan colubrid snakes : I. Introduction and prey genera.

    Science.gov (United States)

    Henderson, Robert W

    1984-05-01

    Approximately 1590 Hispaniolan colubrid snakes representing six genera and eight species were examined for prey remains (Alsophis cantherigerus, Antillophis parvifrons, Darlingtonia haetiana, Hypsirhynchus ferox, Ialtris dorsalis, Uromacer catesbyi, U. frenatus, and U. oxyrhynchus). The snakes were collected at many localities over a span of 80 years.Of 426 prey items, 77.9% were lizards (of which 69.6% were anoles), 19% frogs, 2.6% birds and mammals, and 0.5% other snakes. Darlingtonia was the only snake that did not exploit lizards; it fed exclusively on Eleutherodactylus frogs, including egg clutches. Disregarding Darlingtonia, there is no size class of Hispaniolan colubrids between 20-90 cm SVL that does not prey primarily on Anolis. Certain prey genera are added to, or deleted from, diets depending on snake size, but the data suggest that snake SVL alone does little to dictate what prey genera (or groups) are eaten. Shannon-Wiener values (H') indicate that Darlingtonia has the narrowest trophic niche, while Alsophis and Ialtris have the widest. Values of H' are not correlated with snake SVL, but highly significant (Peats diurnally active (anoles) and diurnally quiescent (hylid frogs) prey with almost equal frequency.Within Maglio's cantherigerus species assemblage, in which an Alsophis cantherigerus-like snake was ancestral to the other species, and in which longsnouted Uromacer are the most morphologically derived, there is an obvious trend toward trophic specialization on Hispaniola. The West Indies have provided an ideal natural laboratory for the investigation of many aspects of vertebrate ecology, and an arena in which to test theories of island biogeography. The most extensively studied West Indian vertebrates have been the lizards of the iguanid genus Anolis. Conversely, the ecology of West Indian snakes has been largely ignored. This is surprising in light of the fact that much has been written about Anolis predation, but little has been written about

  6. Toward a community ecology of landscapes: predicting multiple predator-prey interactions across geographic space.

    Science.gov (United States)

    Schmitz, Oswald J; Miller, Jennifer R B; Trainor, Anne M; Abrahms, Briana

    2017-09-01

    Community ecology was traditionally an integrative science devoted to studying interactions between species and their abiotic environments in order to predict species' geographic distributions and abundances. Yet for philosophical and methodological reasons, it has become divided into two enterprises: one devoted to local experimentation on species interactions to predict community dynamics; the other devoted to statistical analyses of abiotic and biotic information to describe geographic distribution. Our goal here is to instigate thinking about ways to reconnect the two enterprises and thereby return to a tradition to do integrative science. We focus specifically on the community ecology of predators and prey, which is ripe for integration. This is because there is active, simultaneous interest in experimentally resolving the nature and strength of predator-prey interactions as well as explaining patterns across landscapes and seascapes. We begin by describing a conceptual theory rooted in classical analyses of non-spatial food web modules used to predict species interactions. We show how such modules can be extended to consideration of spatial context using the concept of habitat domain. Habitat domain describes the spatial extent of habitat space that predators and prey use while foraging, which differs from home range, the spatial extent used by an animal to meet all of its daily needs. This conceptual theory can be used to predict how different spatial relations of predators and prey could lead to different emergent multiple predator-prey interactions such as whether predator consumptive or non-consumptive effects should dominate, and whether intraguild predation, predator interference or predator complementarity are expected. We then review the literature on studies of large predator-prey interactions that make conclusions about the nature of multiple predator-prey interactions. This analysis reveals that while many studies provide sufficient information

  7. Why plankton modellers should reconsider using rectangular hyperbolic (Michaelis-Menten, Monod descriptions of predator-prey interactions

    Directory of Open Access Journals (Sweden)

    Kevin John Flynn

    2016-09-01

    Full Text Available Rectangular hyperbolic type 2 (RHt2; Michaelis-Menten or Monod -like functions are commonly used to describe predation kinetics in plankton models, either alone or together with a prey selectivity algorithm deploying the same half-saturation constant for all prey types referenced to external prey biomass abundance. We present an analysis that indicates that such descriptions are liable to give outputs that are not plausible according to encounter theory. This is especially so for multi-prey type applications or where changes are made to the maximum feeding rate during a simulation. The RHt2 approach also gives no or limited potential for descriptions of events such as true de-selection of prey, effects of turbulence on encounters, or changes in grazer motility with satiation. We present an alternative, which carries minimal parameterisation effort and computational cost, linking allometric algorithms relating prey abundance and encounter rates to a prey-selection function controlled by satiation. The resultant Satiation-Controlled-Encounter-Based (SCEB function provides a flexible construct describing numeric predator-prey interactions with biomass-feedback control of grazing. The SCEB function includes an attack component similar to that in the Holling disk equation but SCEB differs in having only a single (satiation-based handling constant and an explicit maximum grazing rate. We argue that there is no justification for continuing to deploy RHt2 functions to describe plankton predator-prey interactions.

  8. Presence of Native Prey Does Not Divert Predation on Exotic Pests by Harmonia axyridis in Its Indigenous Range

    Science.gov (United States)

    Zhang, Gui Fen; Lövei, Gábor L; Wu, Xia; Wan, Fang Hao

    2016-01-01

    In China, two invasive pests, Bemisia tabaci MEAM1 (Gennadius) and Frankliniella occidentalis (Pergande), often co-occur with the native pest, Aphis gossypii (Glover), on plants of Malvaceae and Cucurbitaceae. All three are preyed on by the native ladybird, Harmonia axyridis (Pallas); however, the native predator might be expected to prefer native prey to the exotic ones due to a shared evolutionary past. In order to clarify whether the presence of native prey affected the consumption of these two invasive species by the native predator, field-cage experiments were conducted. A duplex qPCR was used to simultaneously detect both non-native pests within the gut of the predator. H. axyridis readily accepted both invasive prey species, but preferred B. tabaci. With all three prey species available, H. axyridis consumption of B. tabaci was 39.3±2.2% greater than consumption of F. occidentalis. The presence of A. gossypii reduced (by 59.9% on B. tabaci, and by 60.6% on F. occidentalis), but did not stop predation on the two exotic prey when all three were present. The consumption of B. tabaci was similar whether it was alone or together with A. gossypii. However, the presence of aphids reduced predation on the invasive thrips. Thus, some invasive prey may be incorporated into the prey range of a native generalist predator even in the presence of preferred native prey. PMID:27391468

  9. The effect of turbidity and prey fish density on consumption rates of piscivorous Eurasian perch Perca fluviatilis

    DEFF Research Database (Denmark)

    Jacobsen, Lene; Berg, Søren; Baktoft, Henrik

    2014-01-01

    piscivorous Eurasian perch Perca fluviatilis L. This was done in outdoor mesocosm (16 m2) experiments with clear water and two levels of turbidity (25 and 105 NTU) and two prey fish densities [3.1 and 12.5 roach Rutilus rutilus (L.) individuals m–2]. Perch consumption rates were affected by visibility less...... than expected, while they were highly affected by increased prey fish density. Perch responded to high prey density in all visibility conditions, indicating that prey density is more crucial for consumption than visibility in turbid lakes...

  10. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    Directory of Open Access Journals (Sweden)

    Hayley S Clements

    Full Text Available Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points with high rates of detection (75% to 100% of simulations, depending on number of break-points and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point. When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah, 82±3% (leopard, 81±2% (lion, 97±2% (spotted hyaena and 96±2% (wild dog of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore

  11. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    Science.gov (United States)

    Clements, Hayley S; Tambling, Craig J; Hayward, Matt W; Kerley, Graham I H

    2014-01-01

    Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points) with high rates of detection (75% to 100% of simulations, depending on number of break-points) and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point). When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah), 82±3% (leopard), 81±2% (lion), 97±2% (spotted hyaena) and 96±2% (wild dog) of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore species.

  12. Prey should hide more randomly when a predator attacks more persistently.

    Science.gov (United States)

    Gal, Shmuel; Alpern, Steve; Casas, Jérôme

    2015-12-06

    When being searched for and then (if found) pursued by a predator, a prey animal has a choice between choosing very randomly among hiding locations so as to be hard to find or alternatively choosing a location from which it is more likely to successfully flee if found. That is, the prey can choose to be hard to find or hard to catch, if found. In our model, capture of prey requires both finding it and successfully pursuing it. We model this dilemma as a zero-sum repeated game between predator and prey, with the eventual capture probability as the pay-off to the predator. We find that the more random hiding strategy is better when the chances of repeated pursuit, which are known to be related to area topography, are high. Our results extend earlier results of Gal and Casas, where there was at most only a single pursuit. In that model, hiding randomly was preferred by the prey when the predator has only a few looks. Thus, our new multistage model shows that the effect of more potential looks is opposite. Our results can be viewed as a generalization of search games to the repeated game context and are in accordance with observed escape behaviour of different animals. © 2015 The Author(s).

  13. Fatal attraction: adaptations to prey on native frogs imperil snakes after invasion of toxic toads.

    Science.gov (United States)

    Hagman, Mattias; Phillips, Benjamin L; Shine, Richard

    2009-08-07

    Adaptations that enhance fitness in one situation can become liabilities if circumstances change. In tropical Australia, native snake species are vulnerable to the invasion of toxic cane toads. Death adders (Acanthophis praelongus) are ambush foragers that (i) attract vertebrate prey by caudal luring and (ii) handle anuran prey by killing the frog then waiting until the frog's chemical defences degrade before ingesting it. These tactics render death adders vulnerable to toxic cane toads (Bufo marinus), because toads elicit caudal luring more effectively than do native frogs, and are more readily attracted to the lure. Moreover, the strategy of delaying ingestion of a toad after the strike does not prevent fatal poisoning, because toad toxins (unlike those of native frogs) do not degrade shortly after the prey dies. In our laboratory and field trials, half of the death adders died after ingesting a toad, showing that the specialized predatory behaviours death adders use to capture and process prey render them vulnerable to this novel prey type. The toads' strong response to caudal luring also renders them less fit than native anurans (which largely ignored the lure): all toads bitten by adders died. Together, these results illustrate the dissonance in behavioural adaptations that can arise following the arrival of invasive species, and reveal the strong selection that occurs when mutually naive species first interact.

  14. Artificial night light alters nocturnal prey interception outcomes for morphologically variable spiders

    Directory of Open Access Journals (Sweden)

    Suet Wai Yuen

    2017-12-01

    Full Text Available Artificial night light has the potential to significantly alter visually-dependent species interactions. However, examples of disruptions of species interactions through changes in light remain rare and how artificial night light may alter predator–prey relationships are particularly understudied. In this study, we examined whether artificial night light could impact prey attraction and interception in Nephila pilipes orb weaver spiders, conspicuous predators who make use of yellow color patterns to mimic floral resources and attract prey to their webs. We measured moth prey attraction and interception responses to treatments where we experimentally manipulated the color/contrast of spider individuals in the field (removed yellow markings and also set up light manipulations. We found that lit webs had lower rates of moth interception than unlit webs. Spider color, however, had no clear impact on moth interception or attraction rates in lit nor unlit webs. The results show that night light can reduce prey interception for spiders. Additionally, this study highlights how environmental and morphological variation can complicate simple predictions of ecological light pollution’s disruption of species interactions.

  15. Extinction and Permanence of a General Predator-Prey System with Impulsive Perturbations

    Directory of Open Access Journals (Sweden)

    Xianning Liu

    2012-01-01

    Full Text Available A general predator-prey system is studied in a scheme where there is periodic impulsive perturbations. This scheme has the potential to protect the predator from extinction but under some conditions may also serve to lead to extinction of the prey. Conditions for extinction and permanence are obtained via the comparison methods involving monotone theory of impulsive systems and multiple Liapunov functions, which establish explicit bounds on solutions. The existence of a positive periodic solution is also studied by the bifurcation theory. Application is given to a Lotka-Volterra predator-prey system with periodic impulsive immigration of the predator. It is shown that the results are quite different from the corresponding system without impulsive immigration, where extinction of the prey can never be achieved. The prey will be extinct or permanent independent of whether the system without impulsive effect immigration is permanent or not. The model and its results suggest an approach of pest control which proves more effective than the classical one.

  16. Falcons pursue prey using visual motion cues: new perspectives from animal-borne cameras.

    Science.gov (United States)

    Kane, Suzanne Amador; Zamani, Marjon

    2014-01-15

    This study reports on experiments on falcons wearing miniature videocameras mounted on their backs or heads while pursuing flying prey. Videos of hunts by a gyrfalcon (Falco rusticolus), gyrfalcon (F. rusticolus)/Saker falcon (F. cherrug) hybrids and peregrine falcons (F. peregrinus) were analyzed to determine apparent prey positions on their visual fields during pursuits. These video data were then interpreted using computer simulations of pursuit steering laws observed in insects and mammals. A comparison of the empirical and modeling data indicates that falcons use cues due to the apparent motion of prey on the falcon's visual field to track and capture flying prey via a form of motion camouflage. The falcons also were found to maintain their prey's image at visual angles consistent with using their shallow fovea. These results should prove relevant for understanding the co-evolution of pursuit and evasion, as well as the development of computer models of predation and the integration of sensory and locomotion systems in biomimetic robots.

  17. Adaptive behaviour and multiple equilibrium states in a predator-prey model.

    Science.gov (United States)

    Pimenov, Alexander; Kelly, Thomas C; Korobeinikov, Andrei; O'Callaghan, Michael J A; Rachinskii, Dmitrii

    2015-05-01

    There is evidence that multiple stable equilibrium states are possible in real-life ecological systems. Phenomenological mathematical models which exhibit such properties can be constructed rather straightforwardly. For instance, for a predator-prey system this result can be achieved through the use of non-monotonic functional response for the predator. However, while formal formulation of such a model is not a problem, the biological justification for such functional responses and models is usually inconclusive. In this note, we explore a conjecture that a multitude of equilibrium states can be caused by an adaptation of animal behaviour to changes of environmental conditions. In order to verify this hypothesis, we consider a simple predator-prey model, which is a straightforward extension of the classic Lotka-Volterra predator-prey model. In this model, we made an intuitively transparent assumption that the prey can change a mode of behaviour in response to the pressure of predation, choosing either "safe" of "risky" (or "business as usual") behaviour. In order to avoid a situation where one of the modes gives an absolute advantage, we introduce the concept of the "cost of a policy" into the model. A simple conceptual two-dimensional predator-prey model, which is minimal with this property, and is not relying on odd functional responses, higher dimensionality or behaviour change for the predator, exhibits two stable co-existing equilibrium states with basins of attraction separated by a separatrix of a saddle point. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Prey-predator dynamics driven by the solar radiation - Part 1

    International Nuclear Information System (INIS)

    Sertorio, L.

    2000-01-01

    In this paper is studied a model ecosystem represented by two components: prey and predator. The predator feeds only on the prey, the prey, in turn, feeds on the solar radiation. In this scheme the two-species dynamics is no longer independent of the external physical conditions. Such independence was instead postulated in the Lotka-Volterra scheme. In this paper is considered the growth of the prey not unbounded (exponential), but logistic, where the saturation factor is governed by the available solar flux, more precisely by the percent of the solar flux that contains the photon frequencies which can drive the photosynthesis. In this way the solar flux represents the driving term of the dynamics, as it is expected in general for a realistic ecosystem. The system is asymptotically stable. The equilibrium values of the prey and predator numbers depend on several parameters. The system contains two nonlinear coupling terms and two coupling parameters. The dependence of the equilibrium point on the coupling parameters is studied in detail. According to this model, it can be defined a predator efficiency and a global solar efficiency. It is discussed the relationship between these two functions of the coupling parameters and the maximum value that the predator population can reach

  19. Assessing arsenic intake from groundwater and rice by residents in Prey Veng province, Cambodia

    International Nuclear Information System (INIS)

    Phan, Kongkea; Phan, Samrach; Heng, Savoeun; Huoy, Laingshun; Kim, Kyoung-Woong

    2014-01-01

    We investigated total daily intake of As by residents in Prey Veng province in the Mekong River basin of Cambodia. Groundwater (n = 11), rice (n = 11) and fingernail (n = 23) samples were randomly collected from the households and analyzed for total As by inductively coupled plasma mass spectrometry. Calculation indicated that daily dose of inorganic As was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL 0.5 equals to 3.0 μg d −1 kg −1 body wt. ). Moreover, positive correlation between As in fingernail and daily dose of As from groundwater and rice and total daily dose of As were found. These results suggest that the Prey Veng residents are exposed to As in groundwater. As in rice is an additional source which is attributable to high As accumulation in human bodies in the Mekong River basin of Cambodia. -- Highlights: • We investigated total daily intake of As in Prey Veng province of Cambodia. • Residents in Prey Veng study area are at risk of As in groundwater. • As in rice is an additional source for high As accumulation in human bodies. -- Calculation of total daily intake indicated that Prey Veng residents are at risk of As in groundwater while As in rice is an additional source for high As accumulation in human bodies

  20. Ultimate predators: lionfish have evolved to circumvent prey risk assessment abilities.

    Science.gov (United States)

    Lönnstedt, Oona M; McCormick, Mark I

    2013-01-01

    Invasive species cause catastrophic alterations to communities worldwide by changing the trophic balance within ecosystems. Ever since their introduction in the mid 1980's common red lionfish, Pterois volitans, are having dramatic impacts on the Caribbean ecosystem by displacing native species and disrupting food webs. Introduced lionfish capture prey at extraordinary rates, altering the composition of benthic communities. Here we demonstrate that the extraordinary success of the introduced lionfish lies in its capacity to circumvent prey risk assessment abilities as it is virtually undetectable by prey species in its native range. While experienced prey damselfish, Chromis viridis, respond with typical antipredator behaviours when exposed to a common predatory rock cod (Cephalopholis microprion) they fail to visibly react to either the scent or visual presentation of the red lionfish, and responded only to the scent (not the visual cue) of a lionfish of a different genus, Dendrochirus zebra. Experienced prey also had much higher survival when exposed to the two non-invasive predators compared to P. volitans. The cryptic nature of the red lionfish has enabled it to be destructive as a predator and a highly successful invasive species.