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Sample records for seed dispersal mutualism

  1. An invasive slug exploits an ant-seed dispersal mutualism.

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    Meadley Dunphy, Shannon A; Prior, Kirsten M; Frederickson, Megan E

    2016-05-01

    Plant-animal mutualisms, such as seed dispersal, are often vulnerable to disruption by invasive species. Here, we show for the first time how a non-ant invasive species negatively affects seed dispersal by ants. We examined the effects of several animal species that co-occur in a temperate deciduous forest-including native and invasive seed-dispersing ants (Aphaenogaster rudis and Myrmica rubra, respectively), an invasive slug (Arion subfuscus), and native rodents-on a native myrmecochorous plant, Asarum canadense. We experimentally manipulated ant, slug, and rodent access to seed depots and measured seed removal. We also video-recorded depots to determine which other taxa interact with seeds. We found that A. rudis was the main disperser of seeds and that A. subfuscus consumed elaiosomes without dispersing seeds. Rodent visitation was rare, and rodent exclusion had no significant effect on seed or elaiosome removal. We then used data obtained from laboratory and field mesocosm experiments to determine how elaiosome robbing by A. subfuscus affects seed dispersal by A. rudis and M. rubra. We found that elaiosome robbing by slugs reduced seed dispersal by ants, especially in mesocosms with A. rudis, which picks up seeds more slowly than M. rubra. Taken together, our results show that elaiosome robbing by an invasive slug reduces seed dispersal by ants, suggesting that invasive slugs can have profound negative effects on seed dispersal mutualisms.

  2. The bonobo-dialium positive interactions: seed dispersal mutualism.

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    Beaune, David; Bretagnolle, François; Bollache, Loïc; Hohmann, Gottfried; Surbeck, Martin; Bourson, Chloé; Fruth, Barbara

    2013-04-01

    A positive interaction is any interaction between individuals of the same or different species (mutualism) that provides a benefit to both partners such as increased fitness. Here we focus on seed dispersal mutualism between an animal (bonobo, Pan paniscus) and a plant (velvet tamarind trees, Dialium spp.). In the LuiKotale rainforest southwest of Salonga National Park, Democratic Republic of Congo, seven species of the genus Dialium account for 29.3% of all trees. Dialium is thus the dominant genus in this forest. Dialium fruits make up a large proportion of the diet of a habituated bonobo community in this forest. During the 6 months of the fruiting season, more than half of the bonobos' feeding time is devoted to Dialium fruits. Furthermore, Dialium fruits contribute a considerable proportion of sugar and protein to bonobos' dietary intake, being among the richest fruits for these nutrients. Bonobos in turn ingest fruits with seeds that are disseminated in their feces (endozoochory) at considerable distances (average: 1.25 km after 24 hr of average transit time). Endozoochory through the gut causes loss of the cuticle protection and tegumentary dormancy, as well as an increase in size by water uptake. Thus, after gut passage, seeds are better able to germinate. We consider other primate species as a potential seed disperser and conclude that Dialium germination is dependent on passage through bonobo guts. This plant-animal interaction highlights positive effects between two major organisms of the Congo basin rainforest, and establishes the role of the bonobo as an efficient disperser of Dialium seeds. Periodicals, Inc. © 2013 Wiley Periodicals, Inc.

  3. Anomalous, extreme weather disrupts obligate seed dispersal mutualism: snow in a subtropical forest ecosystem.

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    Zhou, Youbing; Newman, Chris; Chen, Jin; Xie, Zongqiang; Macdonald, David W

    2013-09-01

    Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January-February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries - migrating ungulates becoming exposed to heightened levels of illegal hunting - causing long-term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant

  4. A strong conditional mutualism limits and enhances seed dispersal and germination of a tropical palm

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    Klinger, R.; Rejmanek, M.

    2010-01-01

    Seed predation and seed dispersal can have strong effects on early life history stages of plants. These processes have often been studied as individual effects, but the degree to which their relative importance co-varies with seed predator abundance and how this influences seed germination rates is poorly understood. Therefore, we used a combination of observations and field experiments to determine the degree to which germination rates of the palm Astrocaryum mexicanum varied with abundance of a small mammal seed predator/disperser, Heteromysdesmarestianus, in a lowland tropical forest. Patterns of abundance of the two species were strongly related; density of H. desmarestianus was low in sites with low density of A. mexicanum and vice versa. Rates of predation and dispersal of A. mexicanum seeds depended on abundance of H. desmarestianus; sites with high densities of H. desmarestianus had the highest rates of seed predation and lowest rates of seed germination, but a greater total number of seeds were dispersed and there was greater density of seedlings, saplings, and adults of A. mexicanum in these sites. When abundance of H. desmarestianus was experimentally reduced, rates of seed predation decreased, but so did dispersal of A. mexicanum seeds. Critically, rates of germination of dispersed seeds were 5 times greater than undispersed seeds. The results suggest that the relationship between A. mexicanum and H. desmarestianus is a conditional mutualism that results in a strong local effect on the abundance of each species. However, the magnitude and direction of these effects are determined by the relative strength of opposing, but related, mechanisms. A. mexicanum nuts provide H. desmarestianus with a critical food resource, and while seed predation on A. mexicanum nuts by H. desmarestianus is very intense, A. mexicanum ultimately benefits because of the relatively high germination rates of its seeds that are dispersed by H. desmarestianus. ?? The Author(s) 2010.

  5. Assessing ecological specialization of an ant-seed dispersal mutualism through a wide geographic range.

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    Manzaneda, Antonio J; Rey, Pedro J

    2009-11-01

    Specialization in species interactions is of central importance for understanding the ecological structure and evolution of plant-animal mutualisms. Most plant-animal mutualisms are facultative and strongly asymmetric. In particular, myrmecochory (seed dispersal by ants) has been regarded as a very generalized interaction. Although some recent studies have suggested that only a few ant species are really important for dispersal, no rigorous measurement of the specialization in ant-seed dispersal mutualisms has been performed. Here, we use individual plants as basic units for replication to investigate the generalization-specialization of the herb Helleborus foetidus on its ant dispersers over a considerable part of its geographical range. We define generalization in terms of diversity components (species richness and evenness) of the ant visitor that realizes dispersal by removing diaspores. We obtain truly comparable values of ant visitor diversity, distinguishing among different functional groups of visitors and identifying incidental visitors and real ant dispersers. Using null model approaches, we test the null hypothesis that ant-mediated dispersal is a generalized mutualism. At least two premises should be confirmed to validate the hypothesis: (1) diaspores are dispersed by multiple ant-visitor species, and (2) diaspore dispersal is significantly equitable. Though up to 37 ant species visited diaspores across 10 populations, only two large formicines, Camponotus cruentatus and Formica lugubris, were responsible for the vast majority of visits resulting in dispersal in most populations and years, which strongly suggests that ant seed dispersal in H. foetidus is ecologically specialized. Interestingly, specialization degree was unrelated to dispersal success across populations. Our study offers new insights into the spatiotemporal dynamics of myrmecochory. We propose the existence of an alternative scenario to extensive generalization. In this new scenario

  6. Endangered plant-parrot mutualisms: seed tolerance to predation makes parrots pervasive dispersers of the Parana pine.

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    Tella, José L; Dénes, Francisco V; Zulian, Viviane; Prestes, Nêmora P; Martínez, Jaime; Blanco, Guillermo; Hiraldo, Fernando

    2016-08-22

    Parrots are largely considered plant antagonists as they usually destroy the seeds they feed on. However, there is evidence that parrots may also act as seed dispersers. We evaluated the dual role of parrots as predators and dispersers of the Critically Endangered Parana pine (Araucaria angustifolia). Eight of nine parrot species predated seeds from 48% of 526 Parana pines surveyed. Observations of the commonest parrot indicated that 22.5% of the picked seeds were dispersed by carrying them in their beaks. Another five parrot species dispersed seeds, at an estimated average distance of c. 250 m. Dispersal distances did not differ from those observed in jays, considered the main avian dispersers. Contrary to jays, parrots often dropped partially eaten seeds. Most of these seeds were handled by parrots, and the proportion of partially eaten seeds that germinated was higher than that of undamaged seeds. This may be explained by a predator satiation effect, suggesting that the large seeds of the Parana pine evolved to attract consumers for dispersal. This represents a thus far overlooked key plant-parrot mutualism, in which both components are threatened with extinction. The interaction is becoming locally extinct long before the global extinction of the species involved.

  7. New mutualism for old: indirect disruption and direct facilitation of seed dispersal following Argentine ant invasion.

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    Rowles, Alexei D; O'Dowd, Dennis J

    2009-01-01

    The indirect effects of biological invasions on native communities are poorly understood. Disruption of native ant communities following invasion by the Argentine ant (Linepithema humile) is widely reported to lead indirectly to the near complete collapse of seed dispersal services. In coastal scrub in southeastern Australia, we examined seed dispersal and handling of two native and two invasive alien plant species at Argentine ant-invaded or -uninvaded sites. The Argentine ant virtually eliminates the native keystone disperser Rhytidoponera victoriae, but seed dispersal did not collapse following invasion. Indeed, Argentine ants directly accounted for 92% of all ant-seed interactions and sustained overall seed dispersal rates. Nevertheless, dispersal quantity and quality among seed species differed between Argentine ant-invaded and -uninvaded sites. Argentine ants removed significantly fewer native Acacia retinodes seeds, but significantly more small seeds of invasive Polygala myrtifolia than did native ants at uninvaded sites. They also handled significantly more large seeds of A. sophorae, but rarely moved them >5 cm, instead recruiting en masse, consuming elaiosomes piecemeal and burying seeds in situ. In contrast, Argentine ants transported and interred P. myrtifolia seeds in their shallow nests. Experiments with artificial diaspores that varied in diaspore and elaiosome masses, but kept seed morphology and elaiosome quality constant, showed that removal by L. humile depended on the interaction of seed size and percentage elaiosome reward. Small diaspores were frequently taken, independent of high or low elaiosome reward, but large artificial diaspores with high reward instead elicited mass recruitment by Argentine ants and were rarely moved. Thus, Argentine ants appear to favour some diaspore types and reject others based largely on diaspore size and percentage reward. Such variability in response indirectly reduces native seed dispersal and can directly

  8. Internal seed dispersal by parrots: an overview of a neglected mutualism.

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    Blanco, Guillermo; Bravo, Carolina; Pacifico, Erica C; Chamorro, Daniel; Speziale, Karina L; Lambertucci, Sergio A; Hiraldo, Fernando; Tella, José L

    2016-01-01

    Despite the fact that parrots (Psitacifformes) are generalist apex frugivores, they have largely been considered plant antagonists and thus neglected as seed dispersers of their food plants. Internal dispersal was investigated by searching for seeds in faeces opportunistically collected at communal roosts, foraging sites and nests of eleven parrot species in different habitats and biomes in the Neotropics. Multiple intact seeds of seven plant species of five families were found in a variable proportion of faeces from four parrot species. The mean number of seeds of each plant species per dropping ranged between one and about sixty, with a maximum of almost five hundred seeds from the cacti Pilosocereus pachycladus in a single dropping of Lear's Macaw (Anodorhynchus leari). All seeds retrieved were small (<3 mm) and corresponded to herbs and relatively large, multiple-seeded fleshy berries and infrutescences from shrubs, trees and columnar cacti, often also dispersed by stomatochory. An overview of the potential constraints driving seed dispersal suggest that, despite the obvious size difference between seeds dispersed by endozoochory and stomatochory, there is no clear difference in fruit size depending on the dispersal mode. Regardless of the enhanced or limited germination capability after gut transit, a relatively large proportion of cacti seeds frequently found in the faeces of two parrot species were viable according to the tetrazolium test and germination experiments. The conservative results of our exploratory sampling and a literature review clearly indicate that the importance of parrots as endozoochorous dispersers has been largely under-appreciated due to the lack of research systematically searching for seeds in their faeces. We encourage the evaluation of seed dispersal and other mutualistic interactions mediated by parrots before their generalized population declines contribute to the collapse of key ecosystem processes.

  9. Internal seed dispersal by parrots: an overview of a neglected mutualism

    Directory of Open Access Journals (Sweden)

    Guillermo Blanco

    2016-02-01

    Full Text Available Despite the fact that parrots (Psitacifformes are generalist apex frugivores, they have largely been considered plant antagonists and thus neglected as seed dispersers of their food plants. Internal dispersal was investigated by searching for seeds in faeces opportunistically collected at communal roosts, foraging sites and nests of eleven parrot species in different habitats and biomes in the Neotropics. Multiple intact seeds of seven plant species of five families were found in a variable proportion of faeces from four parrot species. The mean number of seeds of each plant species per dropping ranged between one and about sixty, with a maximum of almost five hundred seeds from the cacti Pilosocereus pachycladus in a single dropping of Lear’s Macaw (Anodorhynchus leari. All seeds retrieved were small (<3 mm and corresponded to herbs and relatively large, multiple-seeded fleshy berries and infrutescences from shrubs, trees and columnar cacti, often also dispersed by stomatochory. An overview of the potential constraints driving seed dispersal suggest that, despite the obvious size difference between seeds dispersed by endozoochory and stomatochory, there is no clear difference in fruit size depending on the dispersal mode. Regardless of the enhanced or limited germination capability after gut transit, a relatively large proportion of cacti seeds frequently found in the faeces of two parrot species were viable according to the tetrazolium test and germination experiments. The conservative results of our exploratory sampling and a literature review clearly indicate that the importance of parrots as endozoochorous dispersers has been largely under-appreciated due to the lack of research systematically searching for seeds in their faeces. We encourage the evaluation of seed dispersal and other mutualistic interactions mediated by parrots before their generalized population declines contribute to the collapse of key ecosystem processes.

  10. Species-Specific Seed Dispersal in an Obligate Ant-Plant Mutualism

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    Youngsteadt, Elsa; Baca, Jeniffer Alvarez; Osborne, Jason; Schal, Coby

    2009-01-01

    Throughout lowland Amazonia, arboreal ants collect seeds of specific plants and cultivate them in nutrient-rich nests, forming diverse yet obligate and species-specific symbioses called Neotropical ant-gardens (AGs). The ants depend on their symbiotic plants for nest stability, and the plants depend on AGs for substrate and nutrients. Although the AGs are limited to specific participants, it is unknown at what stage specificity arises, and seed fate pathways in AG epiphytes are undocumented. Here we examine the specificity of the ant-seed interaction by comparing the ant community observed at general food baits to ants attracted to and removing seeds of the AG plant Peperomia macrostachya. We also compare seed removal rates under treatments that excluded vertebrates, arthropods, or both. In the bait study, only three of 70 ant species collected P. macrostachya seeds, and 84% of observed seed removal by ants was attributed to the AG ant Camponotus femoratus. In the exclusion experiment, arthropod exclusion significantly reduced seed removal rates, but vertebrate exclusion did not. We provide the most extensive empirical evidence of species specificity in the AG mutualism and begin to quantify factors that affect seed fate in order to understand conditions that favor its departure from the typical diffuse model of plant-animal mutualism. PMID:19194502

  11. Evolution of angiosperm seed disperser mutualisms: the timing of origins and their consequences for coevolutionary interactions between angiosperms and frugivores.

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    Eriksson, Ove

    2016-02-01

    The origins of interactions between angiosperms and fruit-eating seed dispersers have attracted much attention following a seminal paper on this topic by Tiffney (1984). This review synthesizes evidence pertaining to key events during the evolution of angiosperm-frugivore interactions and suggests some implications of this evidence for interpretations of angiosperm-frugivore coevolution. The most important conclusions are: (i) the diversification of angiosperm seed size and fleshy fruits commenced around 80 million years ago (Mya). The diversity of seed sizes, fruit sizes and fruit types peaked in the Eocene around 55 to 50 Mya. During this first phase of the interaction, angiosperms and animals evolving frugivory expanded into niche space not previously utilized by these groups, as frugivores and previously not existing fruit traits appeared. From the Eocene until the present, angiosperm-frugivore interactions have occurred within a broad frame of existing niche space, as defined by fruit traits and frugivory, motivating a separation of the angiosperm-frugivore interactions into two phases, before and after the peak in the early Eocene. (ii) The extinct multituberculates were probably the most important frugivores during the early radiation phase of angiosperm seeds and fleshy fruits. Primates and rodents are likely to have been important in the latter part of this first phase. (iii) Flying frugivores, birds and bats, evolved during the second phase, mainly during the Oligocene and Miocene, thus exploiting an existing diversity of fleshy fruits. (iv) A drastic climate shift around the Eocene-Oligocene boundary (around 34 Mya) resulted in more semi-open woodland vegetation, creating patchily occurring food resources for frugivores. This promoted evolution of a 'flying frugivore niche' exploited by birds and bats. In particular, passerines became a dominant frugivore group worldwide. (v) Fleshy fruits evolved at numerous occasions in many angiosperm families

  12. The conservation physiology of seed dispersal

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    Ruxton, Graeme D.; Schaefer, H. Martin

    2012-01-01

    At a time when plant species are experiencing increasing challenges from climate change, land-use change, harvesting and invasive species, dispersal has become a very important aspect of plant conservation. Seed dispersal by animals is particularly important because some animals disperse seeds to suitable sites in a directed fashion. Our review has two aims: (i) to highlight the various ways plant dispersal by animals can be affected by current anthropogenic change and (ii) to show the important role of plant and (particularly) animal physiology in shaping seed–dispersal interactions. We argue that large-bodied seed dispersers may be particularly important for plant conservation because seed dispersal of large-seeded plants is often more specialized and because large-bodied animals are targeted by human exploitation and have smaller population sizes. We further argue that more specialized seed-dispersal systems on island ecosystems might be particularly at risk from climate change both owing to small population sizes involved but also owing to the likely thermal specialization, particularly on tropical islands. More generally, the inherent vulnerability of seed-dispersal mutualisms to disruption driven by environmental change (as well as their ubiquity) demands that we continue to improve our understanding of their conservation physiology. PMID:22566677

  13. Nest-mediated seed dispersal

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    Robert J. Warren; Jason P. Love; Mark A. Bradford

    2017-01-01

    Many plant seeds travel on the wind and through animal ingestion or adhesion; however, an overlooked dispersal mode may lurk within those dispersal modes. Viable seeds may remain attached or embedded within materials birds gather for nest building. Our objective was to determine if birds inadvertently transport seeds when they forage for plant materials to...

  14. Population consequences of changes in an ant-seed mutualism in Sanguinaria canadensis.

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    Pudlo, Ronald J; Beattie, Andrew J; Culver, David C

    1980-07-01

    Seed dispersal by ants was studied in three populations of the myrmecochore, Sanguinaria canadensis, located in three habitats, each of which showed a different level of disturbance. Frequency of seed removal and the distances seeds were carried by ants were related to plant density, dispersion and the relative proportions of sexual and asexual reproduction in each population. Seeds in the least disturbed habitat were removed frequently and carried, by a wide variety of ants, distances of up to 12 m. Plant density was low and clone size was small. There was a relatively low level of sexual (seed) reproduction but seeds were generally transported well beyond the boundaries of the parent clones. By contrast, at the most disturbed site, plant density was high and clone size was very large. While there was a high level of seed production, seeds were rarely moved by ants and since removal distances were short, the probability of a seed being relocated beyond the limits of the parent clone was miniscule. The third population from a habitat which was intermediate in disturbance yielded data intermediate to the others. The data show that habitat disturbance, in disrupting the ant fauna and hence the ant-seed mutualism, has profound effects upon population density, dispersion and patterns of reproduction. Density-dependent regulation of sexual output predicted, for example, by the Strawberry-Coral model (Williams 1975), is maladaptive when the antseed mutualism is disturbed. We discuss the implications of this for theoretical modeling, the significance of mutualisms and the assessment of disturbance for conservation.

  15. Signals can trump rewards in attracting seed-dispersing ants.

    Directory of Open Access Journals (Sweden)

    Kyle M Turner

    Full Text Available Both rewards and signals are important in mutualisms. In myrmecochory, or seed dispersal by ants, the benefits to plants are relatively well studied, but less is known about why ants pick up and move seeds. We examined seed dispersal by the ant Aphaenogaster rudis of four co-occurring species of plants, and tested whether morphology, chemical signaling, or the nutritional quality of fatty seed appendages called elaiosomes influenced dispersal rates. In removal trials, ants quickly collected diaspores (seeds plus elaiosomes of Asarum canadense, Trillium grandiflorum, and Sanguinaria canadensis, but largely neglected those of T. erectum. This discrepancy was not explained by differences in the bulk cost-benefit ratio, as assessed by the ratio of seed to elaiosome mass. We also provisioned colonies with diaspores from one of these four plant species or no diaspores as a control. Colonies performed best when fed S. canadensis diaspores, worst when fed T. grandiflorum, and intermediately when fed A. canadense, T. erectum, or no diaspores. Thus, the nutritional rewards in elaiosomes affected colony performance, but did not completely predict seed removal. Instead, high levels of oleic acid in T. grandiflorum elaiosomes may explain why ants disperse these diaspores even though they reduce ant colony performance. We show for the first time that different elaiosome-bearing plants provide rewards of different quality to ant colonies, but also that ants appear unable to accurately assess reward quality when encountering seeds. Instead, we suggest that signals can trump rewards as attractants of ants to seeds.

  16. Joshua tree (Yucca brevifolia) seeds are dispersed by seed-caching rodents

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    Vander Wall, S.B.; Esque, T.; Haines, D.; Garnett, M.; Waitman, B.A.

    2006-01-01

    Joshua tree (Yucca brevifolia) is a distinctive and charismatic plant of the Mojave Desert. Although floral biology and seed production of Joshua tree and other yuccas are well understood, the fate of Joshua tree seeds has never been studied. We tested the hypothesis that Joshua tree seeds are dispersed by seed-caching rodents. We radioactively labelled Joshua tree seeds and followed their fates at five source plants in Potosi Wash, Clark County, Nevada, USA. Rodents made a mean of 30.6 caches, usually within 30 m of the base of source plants. Caches contained a mean of 5.2 seeds buried 3-30 nun deep. A variety of rodent species appears to have prepared the caches. Three of the 836 Joshua tree seeds (0.4%) cached germinated the following spring. Seed germination using rodent exclosures was nearly 15%. More than 82% of seeds in open plots were removed by granivores, and neither microsite nor supplemental water significantly affected germination. Joshua tree produces seeds in indehiscent pods or capsules, which rodents dismantle to harvest seeds. Because there is no other known means of seed dispersal, it is possible that the Joshua tree-rodent seed dispersal interaction is an obligate mutualism for the plant.

  17. Seed dispersal potential of Asian elephants

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    Harich, Franziska K.; Treydte, Anna C.; Ogutu, Joseph O.; Roberts, John E.; Savini, Chution; Bauer, Jan M.; Savini, Tommaso

    2016-11-01

    Elephants, the largest terrestrial mega-herbivores, play an important ecological role in maintaining forest ecosystem diversity. While several plant species strongly rely on African elephants (Loxodonta africana; L. cyclotis) as seed dispersers, little is known about the dispersal potential of Asian elephants (Elephas maximus). We examined the effects of elephant fruit consumption on potential seed dispersal using the example of a tree species with mega-faunal characteristics, Dillenia indica L., in Thailand. We conducted feeding trials with Asian elephants to quantify seed survival and gut passage times (GPT). In total, 1200 ingested and non-ingested control seeds were planted in soil and in elephant dung to quantify differences in germination rates in terms of GPT and dung treatment. We used survival analysis as a novel approach to account for the right-censored nature of the data obtained from germination experiments. The average seed survival rate was 79% and the mean GPT was 35 h. The minimum and maximum GPT were 20 h and 72 h, respectively. Ingested seeds were significantly more likely to germinate and to do so earlier than non-ingested control seeds (P = 0.0002). Seeds with the longest GPT displayed the highest germination success over time. Unexpectedly, seeds planted with dung had longer germination times than those planted without. We conclude that D. indica does not solely depend on but benefits from dispersal by elephants. The declining numbers of these mega-faunal seed dispersers might, therefore, have long-term negative consequences for the recruitment and dispersal dynamics of populations of certain tree species.

  18. Effect of Seed Density on Splash Cup Seed Dispersal

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    Wigger, Patrick; Pepper, Rachel

    2017-11-01

    Splash cup plants are plants that utilize a small, mm-sized cup filled with seeds as a method of seed dispersal. The cup uses kinetic energy of an incident raindrop in order to project the seeds away from the plant up to 1 meter. The dispersal distance is important to ensure the offspring are not clustered too tightly to the parent plant. It has previously been found that a cup angle of 40 degrees to the horizontal is optimal for maximum dispersal of water from cups with no seeds. In this study we examine if the 40 degree cup is optimal for cups containing seeds with varying densities. We released uniform water drops above 5.0 mm 3D printed models of splash cups, using 1.0 mm plastic and glass microspheres of varying densities to simulate seeds. We observed the dispersal characteristics of each bead type by measuring the final seed locations after each splash, and by recording high speed video to determine the angle and velocity of the seeds as they exited the cup.

  19. Using seed-tagging methods for assessing post-dispersal seed fate in rodent-dispersed trees

    NARCIS (Netherlands)

    Xiao, ZS; Jansen, PA; Zhang, ZB

    2006-01-01

    Seed tagging is widely used for tracking seeds during dispersal by seed-caching animals. No studies, however, have fully examined the effects of seed tagging on post-dispersal seed fate. We studied how two seed tagging techniques - thread-marking and wire tin-tagging - affected seed fate by placing

  20. Using seed-tagging methods for assessing post-dispersal seed fate in rodent-dispersed trees.

    NARCIS (Netherlands)

    Xiao, Z.; Jansen, P.A.; Zhang, Z.

    2006-01-01

    Seed tagging is widely used for tracking seeds during dispersal by seed-caching animals. No studies, however, have fully examined the effects of seed tagging on post-dispersal seed fate. We studied how two seed tagging techniques – thread-marking and wire tin-tagging – affected seed fate by placing

  1. Seed Dispersal Potential of Asian Elephants

    DEFF Research Database (Denmark)

    Harich, Franziska K.; Treydte, Anna Christina; Ogutu, Joseph Ochieng

    2016-01-01

    of Asian elephants (Elephas maximus). We examined the effects of elephant fruit consumption on potential seed dispersal using the example of a tree species with mega-faunal characteristics, Dillenia indica L., in Thailand. We conducted feeding trials with Asian elephants to quantify seed survival and gut...

  2. Consistent individual differences in seed disperser quality in a seed-eating fish

    NARCIS (Netherlands)

    Pollux, Bart J.A.

    2017-01-01

    Animal-mediated seed dispersal (zoochory) is considered to be an important mechanism regulating biological processes at larger spatial scales. To date, intra-specific variation in seed disperser quality within seed-dispersing animals has not been studied. Here, I employed seed feeding trials to

  3. Seed dispersal by macaws shapes the landscape of an Amazonian ecosystem.

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    Baños-Villalba, Adrián; Blanco, Guillermo; Díaz-Luque, José A; Dénes, Francisco V; Hiraldo, Fernando; Tella, José L

    2017-08-07

    Seed dispersal is one of the most studied plant-animal mutualisms. It has been proposed that the dispersal of many large-seeded plants from Neotropical forests was primarily conducted by extinct megafauna, and currently by livestock. Parrots can transport large fruits using their beaks, but have been overlooked as seed dispersers. We demonstrate that three macaws (Ara ararauna, A. glaucogularis and A. severus) are the main dispersers of the large-seeded motacú palm Attalea princeps, which is the biomass-dominant tree in the Bolivian Amazonian savannas. Macaws dispersed fruits at high rates (75-100% of fruits) to distant (up to 1200 m) perching trees, where they consumed the pulp and discarded entire seeds, contributing to forest regeneration and connectivity between distant forests islands. The spatial distribution of immature palms was positively associated to the proximity to macaws' perching trees and negatively to the proximity to cattle paths. The disperser role of livestock, presumably a substitute for extinct megafauna, had little effect due to soil compaction, trampling and herbivory. Our results underscore the importance of macaws as legitimate, primary dispersers of large-seeded plants at long distances and, specifically, their key role in shaping the landscape structure and functioning of this Amazonian biome.

  4. Overseas seed dispersal by migratory birds.

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    Viana, Duarte S; Gangoso, Laura; Bouten, Willem; Figuerola, Jordi

    2016-01-13

    Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has never been directly observed nor quantified. By sampling birds caught while in migratory flight by GPS-tracked wild falcons, we show that migratory birds transport seeds over hundreds of kilometres and mediate dispersal from mainland to oceanic islands. Up to 1.2% of birds that reached a small island of the Canary Archipelago (Alegranza) during their migration from Europe to Sub-Saharan Africa carried seeds in their guts. The billions of birds making seasonal migrations each year may then transport millions of seeds. None of the plant species transported by the birds occurs in Alegranza and most do not occur on nearby Canary Islands, providing a direct example of the importance of environmental filters in hampering successful colonization by immigrant species. The constant propagule pressure generated by these LDD events might, nevertheless, explain the colonization of some islands. Hence, migratory birds can mediate rapid range expansion or shifts of many plant taxa and determine their distribution. © 2016 The Author(s).

  5. Milkweed Seed Dispersal: A Means for Integrating Biology and Physics.

    Science.gov (United States)

    Bisbee, Gregory D.; Kaiser, Cheryl A.

    1997-01-01

    Describes an activity that integrates biology and physics concepts by experimenting with the seed dispersal of common milkweed or similar wind-dispersed seeds. Student teams collect seeds and measure several parameters, review principles of trajectory motion, perform experiments, and graph data. Students examine the ideas of…

  6. Flowering and seed dispersal of dwarfmistletoe (Arceuthobium campylopodum in California

    Science.gov (United States)

    Robert F. Scharpf

    1965-01-01

    Under the short growing season of the Sierra Nevada, both flowering and seed dispersal of Arceuthobium campylopodum occurred earlier in the fall and dispersal extended for a shorter duration than at lower elevations and along the coast of California. Also in years of above normal surrmer temperatures, flowering and seed dispersal occurred earlier in...

  7. Introducing cultivated trees into the wild: Wood pigeons as dispersers of domestic olive seeds

    Science.gov (United States)

    Perea, Ramón; Gutiérrez-Galán, Alejandro

    2016-02-01

    Animals may disperse cultivated trees outside the agricultural land, favoring the naturalization or, even, the invasiveness of domestic plants. However, the ecological and conservation implications of new or unexplored mutualisms between cultivated trees and wild animals are still far from clear. Here, we examine the possible role of an expanding and, locally, overabundant pigeon species (Columba palumbus) as an effective disperser of domestic olive trees (Olea europaea), a widespread cultivated tree, considered a naturalized and invasive species in many areas of the world. By analyzing crop and gizzard content we found that olive fruits were an important food item for pigeons in late winter and spring. A proportion of 40.3% pigeons consumed olive seeds, with an average consumption of 7.8 seeds per pigeon and day. Additionally, most seed sizes (up to 0.7 g) passed undamaged through the gut and were dispersed from cultivated olive orchards to areas covered by protected Mediterranean vegetation, recording minimal dispersal distances of 1.8-7.4 km. Greenhouse experiments showed that seeds dispersed by pigeons significantly favored the germination and establishment in comparison to non-ingested seeds. The ability of pigeons to effectively disperse domestic olive seeds may facilitate the introduction of cultivated olive trees into natural systems, including highly-protected wild olive woodlands. We recommend harvesting ornamental olive trees to reduce both pigeon overpopulation and the spread of artificially selected trees into the natural environment.

  8. Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.

    Science.gov (United States)

    Guimarães, Paulo R; Galetti, Mauro; Jordano, Pedro

    2008-03-05

    Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few ( 100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among-population structuring. These effects could be extended to other plant species dispersed by large

  9. Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.

    Directory of Open Access Journals (Sweden)

    Paulo R Guimarães

    Full Text Available BACKGROUND: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3 kg, yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. METHODOLOGY/PRINCIPAL FINDINGS: We introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size with either a single or few ( 100 seeds. Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness. CONCLUSIONS/SIGNIFICANCE: Megafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among

  10. Timing of seed dispersal and seed dormancy in Brazilian savanna: two solutions to face seasonality.

    Science.gov (United States)

    Escobar, Diego F E; Silveira, Fernando A O; Morellato, Leonor Patricia C

    2018-02-07

    The relationship between fruiting phenology and seed dispersal syndrome is widely recognized; however, the interaction of dormancy classes and plant life-history traits in relation to fruiting phenology and seed dispersal is understudied. Here we examined the relationship between fruiting season and seed dormancy and how this relationship is modulated by dormancy classes, dispersal syndromes, seed mass and seed moisture content in a Brazilian savanna (cerrado). Dormancy classes (non-dormancy and physical, morphological, morphophysiological, physiological and physiophysical dormancy) of 34 cerrado species were experimentally determined. Their seed dispersal syndrome (autochory, anemochory, zoochory), dispersal season (rainy, dry, rainy-to-dry and dry-to-rainy transitions), seed mass and moisture contents, and the estimated germination date were also determined. Log-linear models were used to evaluate how dormancy and dormancy classes are related to dispersal season and syndrome. The proportions of dormant and non-dormant species were similar in cerrado. The community-estimated germination date was seasonal, occurring at the onset of rainy season. Overall, anemochorous non-dormant species released seeds during the dry-to-rainy transition; autochorous physically dormant species dispersed seeds during the dry season and rainy-to-dry transition; zoochorous species dispersed non-dormant seeds during the dry and rainy seasons, while species with morphological, morphophysiological or physiological dormancy dispersed seeds in the transitional seasons. Seed mass differed among dispersal seasons and dormancy classes, but seed moisture content did not vary with dispersal syndrome, season or dormancy class. The beginning of the rainy season was the most favourable period for seed germination in cerrado, and the germination phenology was controlled by both the timing of seed dispersal and seed dormancy. Dormancy class was influenced by dispersal syndrome and season. Moreover

  11. Seed dispersal by vertebrates in Madagascar's forests: review and ...

    African Journals Online (AJOL)

    seeds. Thus, understanding plant - frugivore interactions is of critical importance for the conservation and ... ance of many plant species on frugivores for their dispersal. Understanding this ecosystem service can provide us ... edge of this ecosystem service in Madagascar. Understanding seed dispersal is important because ...

  12. Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

    OpenAIRE

    Guimarães, Paulo R.; Galetti, Mauro; Jordano, Pedro

    2008-01-01

    Background: Some neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals .103 kg), yet these dispersers were extinct in South America 10–15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics. Methodology/Principal Findings: We introduce an operational definition of megafaunal fruits and perform a comparativ...

  13. Dispersal of seeds from splash-cup plants

    Science.gov (United States)

    Pepper, Rachel

    2017-11-01

    Splash cup plants disperse their seeds with the help of raindrops. The seeds sit in a small (mm-scale) conical cup and are ejected upon drop impact. The seeds are ejected at velocities up to five times the impact speed of the raindrop, and are dispersed up to 1 m away from the parent plant, which is only a few cm high. Previous work investigating the mechanism of this remarkable dispersal predicted an optimum cup opening angle of around 40°, which matched reasonably well with experiments performed with 3D-printed splash cup models. Those experiments were done with off-center drop impacts on initially empty cups with no seeds. We discuss similar experiments for cups that are not initially empty, but rather contain seed mimics, water, or both seeds and water. For some of these realistic initial states results are strikingly different from empty cups. Connections to theory will also be discussed.

  14. Adaptive Advantage of Myrmecochory in the Ant-Dispersed Herb Lamium amplexicaule (Lamiaceae): Predation Avoidance through the Deterrence of Post-Dispersal Seed Predators.

    Science.gov (United States)

    Tanaka, Koki; Ogata, Kanako; Mukai, Hiromi; Yamawo, Akira; Tokuda, Makoto

    2015-01-01

    Seed dispersal by ants (myrmecochory) is found worldwide, but the benefits that plants obtain from this mutualism remain uncertain. In the present study, we conducted laboratory experiments to demonstrate seed predator avoidance as a benefit of myrmecochory using the annual ant-dispersed herb Lamium amplexicaule, the disperser ant Tetramorium tsushimae, and the seed predatory burrower bug Adomerus rotundus. We compared the predation intensity of Lamium amplexicaule seeds by Adomerus rotundus under the presence or absence of Tetramorium tsushimae. Both the number of seeds sucked by Adomerus rotundus adults and the feeding duration of sucked seeds by nymphs were significantly reduced in the presence of ants. This effect was most likely due to the behavioral alteration of Adomerus rotundus in response to the ant presence, because ants seldom predated Adomerus rotundus during the experiment. Our results demonstrated that the presence of ants decreases post-dispersal seed predation, even when the ants do not bury the seeds. The present study thus suggests that the non-consumptive effects of ants on seed predators benefit myrmecochorous plants.

  15. Adaptive Advantage of Myrmecochory in the Ant-Dispersed Herb Lamium amplexicaule (Lamiaceae: Predation Avoidance through the Deterrence of Post-Dispersal Seed Predators.

    Directory of Open Access Journals (Sweden)

    Koki Tanaka

    Full Text Available Seed dispersal by ants (myrmecochory is found worldwide, but the benefits that plants obtain from this mutualism remain uncertain. In the present study, we conducted laboratory experiments to demonstrate seed predator avoidance as a benefit of myrmecochory using the annual ant-dispersed herb Lamium amplexicaule, the disperser ant Tetramorium tsushimae, and the seed predatory burrower bug Adomerus rotundus. We compared the predation intensity of Lamium amplexicaule seeds by Adomerus rotundus under the presence or absence of Tetramorium tsushimae. Both the number of seeds sucked by Adomerus rotundus adults and the feeding duration of sucked seeds by nymphs were significantly reduced in the presence of ants. This effect was most likely due to the behavioral alteration of Adomerus rotundus in response to the ant presence, because ants seldom predated Adomerus rotundus during the experiment. Our results demonstrated that the presence of ants decreases post-dispersal seed predation, even when the ants do not bury the seeds. The present study thus suggests that the non-consumptive effects of ants on seed predators benefit myrmecochorous plants.

  16. Adaptive Advantage of Myrmecochory in the Ant-Dispersed Herb Lamium amplexicaule (Lamiaceae): Predation Avoidance through the Deterrence of Post-Dispersal Seed Predators

    Science.gov (United States)

    Tanaka, Koki; Ogata, Kanako; Mukai, Hiromi; Yamawo, Akira; Tokuda, Makoto

    2015-01-01

    Seed dispersal by ants (myrmecochory) is found worldwide, but the benefits that plants obtain from this mutualism remain uncertain. In the present study, we conducted laboratory experiments to demonstrate seed predator avoidance as a benefit of myrmecochory using the annual ant-dispersed herb Lamium amplexicaule, the disperser ant Tetramorium tsushimae, and the seed predatory burrower bug Adomerus rotundus. We compared the predation intensity of Lamium amplexicaule seeds by Adomerus rotundus under the presence or absence of Tetramorium tsushimae. Both the number of seeds sucked by Adomerus rotundus adults and the feeding duration of sucked seeds by nymphs were significantly reduced in the presence of ants. This effect was most likely due to the behavioral alteration of Adomerus rotundus in response to the ant presence, because ants seldom predated Adomerus rotundus during the experiment. Our results demonstrated that the presence of ants decreases post-dispersal seed predation, even when the ants do not bury the seeds. The present study thus suggests that the non-consumptive effects of ants on seed predators benefit myrmecochorous plants. PMID:26197397

  17. Oak habitat recovery on California's largest islands: Scenarios for the role of corvid seed dispersal

    Science.gov (United States)

    Pesendorfer, Mario B.; Baker, Christopher M.; Stringer, Martin; McDonald-Madden, Eve; Bode, Michael; McEachern, A. Kathryn; Morrison, Scott A.; Sillett, T. Scott

    2018-01-01

    Seed dispersal by birds is central to the passive restoration of many tree communities. Reintroduction of extinct seed dispersers can therefore restore degraded forests and woodlands. To test this, we constructed a spatially explicit simulation model, parameterized with field data, to consider the effect of different seed dispersal scenarios on the extent of oak populations. We applied the model to two islands in California's Channel Islands National Park (USA), one of which has lost a key seed disperser.We used an ensemble modelling approach to simulate island scrub oak (Quercus pacifica) demography. The model was developed and trained to recreate known population changes over a 20-year period on 250-km2 Santa Cruz Island, and incorporated acorn dispersal by island scrub-jays (Aphelocoma insularis), deer mice (Peromyscus maniculatus) and gravity, as well as seed predation. We applied the trained model to 215-km2 Santa Rosa Island to examine how reintroducing island scrub-jays would affect the rate and pattern of oak population expansion. Oak habitat on Santa Rosa Island has been greatly reduced from its historical extent due to past grazing by introduced ungulates, the last of which were removed by 2011.Our simulation model predicts that a seed dispersal scenario including island scrub-jays would increase the extent of the island scrub oak population on Santa Rosa Island by 281% over 100 years, and by 544% over 200 years. Scenarios without jays would result in little expansion. Simulated long-distance seed dispersal by jays also facilitates establishment of discontinuous patches of oaks, and increases their elevational distribution.Synthesis and applications. Scenario planning provides powerful decision support for conservation managers. We used ensemble modelling of plant demographic and seed dispersal processes to investigate whether the reintroduction of seed dispersers could provide cost-effective means of achieving broader ecosystem restoration goals on

  18. Modelling long-distance seed dispersal in heterogeneous landscapes.

    Energy Technology Data Exchange (ETDEWEB)

    Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

    2008-01-01

    1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, ‘holding’ them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our

  19. Mutuality

    DEFF Research Database (Denmark)

    Arnould, E. J.; Rose, A. S.

    2016-01-01

    and epistemological grounds and reproduces an array of problematic modernist dichotomies (e.g., agency/structure, nurturing family/instrumental public, gift/market, and altruism/self-interest) that significantly constrain the analytical enterprise. This work redresses some of the conceptual problems in the current...... formulation. The critique highlights a focus on resource distribution based on a more holistic, socially grounded perspective on circulation. We offer the alternative concept of mutuality or generalized exchange and the metaphor of inclusion rather than exchange as central to this perspective. We argue...

  20. Patterns of movement and seed dispersal by three lemur species.

    Science.gov (United States)

    Razafindratsima, Onja H; Jones, Thomas A; Dunham, Amy E

    2014-01-01

    We combined data on gut-passage times, feeding, and movement to explore the patterns of seed dispersal by Eulemur rubriventer, Eulemur rufrifrons, and Varecia variegata editorum lemurs in Ranomafana National Park, Madagascar. These lemur species deposited less than half of their consumed seeds >100 m away from conspecific trees (40-50%). Long-distance dispersal (>500 m) was rare and average dispersal distances were short relative to those reported of similar-sized haplorrhine primates. The three lemur species showed no significant differences in mean seed-dispersal distances. However, they differed in the shape of their frequency distributions of seed-dispersal distances as a result of differences in how they moved through their habitats. The short distances of seed dispersal we observed and the depauperate frugivorous fauna in Madagascar suggest seed-dispersal may be more limited than in other tropical forests with important implications for plant-community dynamics, biodiversity maintenance, and restoration efforts in Madagascar. © 2013 Wiley Periodicals, Inc.

  1. Seed source, seed traits, and frugivore habits: Implications for dispersal quality of two sympatric primates.

    Science.gov (United States)

    Benítez-Malvido, Julieta; González-Di Pierro, Ana Ma; Lombera, Rafael; Guillén, Susana; Estrada, Alejandro

    2014-06-01

    • Premise of the study: Frugivore selection of fruits and treatment of seeds together with seed deposition site are crucial for the population dynamics of vertebrate-dispersed plants. However, frugivore species may influence dispersal quality differently even when feeding on the same fruit species and, while animals disperse some seeds, others simply fall beneath the parent plant.• Methods: In southern Mexico, we investigated to see if within-species seed traits (i.e., length, width, weight, and volume) and germination success differed according to seed source. For five tropical tree species we obtained ingested seeds from two sources, howler monkey (Alouatta pigra) and spider monkey (Ateles geoffroyi) feces; and noningested seeds from two sources, the ground and tree crowns (with predispersed seeds used as control).• Key results: A principal components' analysis showed that traits of seeds ingested by howler monkeys differed from other sources while seeds ingested by spider monkeys were similar to noningested seeds. Howlers consumed on average the larger seeds in Ampelocera hottlei, Brosimum lactescens, and Dialium guianense. Both primate species consumed the smaller seeds in Spondias mombin, while no seed trait differences among seed sources were found in Spondias radlkoferi. For all five tree species, germination rate was greatest for seeds ingested by howler monkeys.• Conclusions: For the studied plant species, seed ingestion by howler monkeys confers higher dispersal quality than ingestion by spider monkeys or nondispersal. Dispersal services of both primate species, however, are not redundant and may contribute to germination heterogeneity within plant populations in tropical forests. © 2014 Botanical Society of America, Inc.

  2. Epizoochory in dry forest iguanas: an overlooked seed dispersal mechanism?

    Directory of Open Access Journals (Sweden)

    Eloisa Lasso

    2015-01-01

    Full Text Available The role of animals as seed dispersal vectors is widely acknowledged, including dispersal by reptiles (saurochory. Most reports of saurochory have been via endozoochory, through feces deposition. We present the first evidence of epizoochory in Iguanas from a dry forest in Colombia via seeds attached to the snout. Our results show that seeds of a cactus Melocactus curvispinus ingested by iguana suffers from their passage through the digestive tract while seeds transported while attached to the snout germinate faster and in higher numbers. Our data suggest that we may have overlooked an alternative means of seed dispersal by lizards that does not comprise a passage through their digestive tract, and that deserves further attention for the understanding of dry forest ecology.

  3. Uncoupling the effects of seed predation and seed dispersal by granivorous ants on plant population dynamics.

    Directory of Open Access Journals (Sweden)

    Xavier Arnan

    Full Text Available Secondary seed dispersal is an important plant-animal interaction, which is central to understanding plant population and community dynamics. Very little information is still available on the effects of dispersal on plant demography and, particularly, for ant-seed dispersal interactions. As many other interactions, seed dispersal by animals involves costs (seed predation and benefits (seed dispersal, the balance of which determines the outcome of the interaction. Separate quantification of each of them is essential in order to understand the effects of this interaction. To address this issue, we have successfully separated and analyzed the costs and benefits of seed dispersal by seed-harvesting ants on the plant population dynamics of three shrub species with different traits. To that aim a stochastic, spatially-explicit individually-based simulation model has been implemented based on actual data sets. The results from our simulation model agree with theoretical models of plant response dependent on seed dispersal, for one plant species, and ant-mediated seed predation, for another one. In these cases, model predictions were close to the observed values at field. Nonetheless, these ecological processes did not affect in anyway a third species, for which the model predictions were far from the observed values. This indicates that the balance between costs and benefits associated to secondary seed dispersal is clearly related to specific traits. This study is one of the first works that analyze tradeoffs of secondary seed dispersal on plant population dynamics, by disentangling the effects of related costs and benefits. We suggest analyzing the effects of interactions on population dynamics as opposed to merely analyzing the partners and their interaction strength.

  4. Modeling seed dispersal distances: implications for transgenic Pinus taeda.

    Science.gov (United States)

    Williams, Claire G; LaDeau, Shannon L; Oren, Ram; Katul, Gabriel G

    2006-02-01

    Predicting forest-tree seed dispersal across a landscape is useful for estimating gene flow from genetically engineered (GE) or transgenic trees. The question of biocontainment has yet to be resolved, although field-trial permits for transgenic forest trees are on the rise. Most current field trials in the United States occur in the Southeast where Pinus taeda L., an indigenous species, is the major timber commodity. Seed dispersal distances were simulated using a model where the major determinants were: (1) forest canopy height at seed release, (2) terminal velocity of the seeds, (3) absolute seed release, and (4) turbulent-flow statistics, all of which were measured or determined within a P. taeda plantation established from seeds collected from wild forest-tree stands at the Duke Forest near Durham, North Carolina, USA. In plantations aged 16 and 25 years our model results showed that most of the seeds fell within local-neighborhood dispersal distances, with estimates ranging from 0.05 to 0.14 km from the source. A fraction of seeds was uplifted above the forest canopy and moved via the long-distance dispersal (LDD) process as far as 11.9-33.7 km. Out of 10(5) seeds produced per hectare per year, roughly 440 seeds were predicted to be uplifted by vertical eddies above the forest canopy and transported via LDD. Of these, 70 seeds/ha traveled distances in excess of 1 km from the source, a distance too great to serve as a biocontainment zone. The probability of LDD occurrence of transgenic conifer seeds at distances exceeding 1 km approached 100%.

  5. Seed dispersal limitations shift over time in tropical forest restoration.

    Science.gov (United States)

    Reid, J Leighton; Holl, Karen D; Zahawi, Rakan A

    2015-06-01

    Past studies have shown that tropical forest regeneration on degraded farmlands is initially limited by lack of seed dispersal, but few studies have tracked changes in abundance and composition of seed rain past the first few years after land abandonment. We measured seed rain for 12 months in 10 6-9-year-old restoration sites and five mature, reference forests in southern Costa Rica in order to learn (1) if seed rain limitation persists past the first few years of regeneration; (2) how restoration treatments influence seed community structure and composition; and (3) whether seed rain limitation is contingent on landscape context. Each restoration site contained three 0.25-ha treatment plots: (1) a naturally regenerating control, (2) tree islands, and (3) a mixed-species tree plantation. Sites spanned a deforestation gradient with 9-89% forest area within 500 m around the treatment plots. Contrary to previous studies, we found that tree seeds were abundant and ubiquitous across all treatment plots (585.1 ± 142.0 seeds · m(-2) · yr(-1) [mean ± SE]), indicating that lack of seed rain ceased to limit forest regeneration within the first decade of recovery. Pioneer trees and shrubs comprised the vast majority of seeds, but compositional differences between restoration sites and reference forests were driven by rarer, large-seeded species. Large, animal-dispersed tree seeds were more abundant in tree islands (4.6 ± 2.9 seeds · m(-2) · yr(-1)) and plantations (5.8 ± 3.0 seeds · m(-2) · yr(-1)) than control plots (0.2 ± 0.1 seeds · m(-2) · yr(-1)), contributing to greater tree species richness in actively restored plots. Planted tree species accounted for forest cover effects on seed rain, consistent with previous studies. We conclude that seed rain limitation shifted from an initial, complete lack of tree seeds to a specific limitation on large-seeded, mature forest species over the first decade. Although total seed abundance was equal among restoration

  6. How does pollen versus seed dispersal affect niche evolution?

    Science.gov (United States)

    Aguilée, Robin; Shaw, Frank H; Rousset, François; Shaw, Ruth G; Ronce, Ophélie

    2013-03-01

    In heterogeneous landscapes, the genetic and demographic consequences of dispersal influence the evolution of niche width. Unless pollen is limiting, pollen dispersal does not contribute directly to population growth. However, by disrupting local adaptation, it indirectly affects population dynamics. We compare the effect of pollen versus seed dispersal on the evolution of niche width in heterogeneous habitats, explicitly considering the feedback between maladaptation and demography. We consider two scenarios: the secondary contact of two subpopulations, in distinct, formerly isolated habitats, and the colonization of an empty habitat with dispersal between the new and ancestral habitat. With an analytical model, we identify critical levels of genetic variance leading to niche contraction (secondary contact scenario), or expansion (new habitat scenario). We confront these predictions with simulations where the genetic variance freely evolves. Niche contraction occurs when habitats are very different. It is faster as total gene flow increases or as pollen predominates in overall gene flow. Niche expansion occurs when habitat heterogeneity is not too high. Seed dispersal accelerates it, whereas pollen dispersal tends to retard it. In both scenarios very high seed dispersal leads to extinction. Overall, our results predict a wider niche for species dispersing seeds more than pollen. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  7. Dispersal of Transgenes through Maize Seed Systems in Mexico

    Science.gov (United States)

    Dyer, George A.; Serratos-Hernández, J. Antonio; Perales, Hugo R.; Gepts, Paul; Piñeyro-Nelson, Alma; Chávez, Angeles; Salinas-Arreortua, Noé; Yúnez-Naude, Antonio; Taylor, J. Edward; Alvarez-Buylla, Elena R.

    2009-01-01

    Objectives Current models of transgene dispersal focus on gene flow via pollen while neglecting seed, a vital vehicle for gene flow in centers of crop origin and diversity. We analyze the dispersal of maize transgenes via seeds in Mexico, the crop's cradle. Methods We use immunoassays (ELISA) to screen for the activity of recombinant proteins in a nationwide sample of farmer seed stocks. We estimate critical parameters of seed population dynamics using household survey data and combine these estimates with analytical results to examine presumed sources and mechanisms of dispersal. Results Recombinant proteins Cry1Ab/Ac and CP4/EPSPS were found in 3.1% and 1.8% of samples, respectively. They are most abundant in southeast Mexico but also present in the west-central region. Diffusion of seed and grain imported from the United States might explain the frequency and distribution of transgenes in west-central Mexico but not in the southeast. Conclusions Understanding the potential for transgene survival and dispersal should help design methods to regulate the diffusion of germplasm into local seed stocks. Further research is needed on the interactions between formal and informal seed systems and grain markets in centers of crop origin and diversification. PMID:19503610

  8. Biomimetics on seed dispersal: survey and insights for space exploration.

    Science.gov (United States)

    Pandolfi, Camilla; Izzo, Dario

    2013-06-01

    Seeds provide the vital genetic link and dispersal agent between successive generations of plants. Without seed dispersal as a means of reproduction, many plants would quickly die out. Because plants lack any sort of mobility and remain in the same spot for their entire lives, they rely on seed dispersal to transport their offspring throughout the environment. This can be accomplished either collectively or individually; in any case as seeds ultimately abdicate their movement, they are at the mercy of environmental factors. Thus, seed dispersal strategies are characterized by robustness, adaptability, intelligence (both behavioral and morphological), and mass and energy efficiency (including the ability to utilize environmental sources of energy available): all qualities that advanced engineering systems aim at in general, and in particular those that need to enable complex endeavors such as space exploration. Plants evolved and adapted their strategy according to their environment, and taken together, they enclose many desirable characteristics that a space mission needs to have. Understanding in detail how plants control the development of seeds, fabricate structural components for their dispersal, build molecular machineries to keep seeds dormant up to the right moment and monitor the environment to release them at the right time could provide several solutions impacting current space mission design practices. It can lead to miniaturization, higher integration and packing efficiency, energy efficiency and higher autonomy and robustness. Consequently, there would appear to be good reasons for considering biomimetic solutions from plant kingdom when designing space missions, especially to other celestial bodies, where solid and liquid surfaces, atmosphere, etc constitute and are obviously parallel with the terrestrial environment where plants evolved. In this paper, we review the current state of biomimetics on seed dispersal to improve space mission design.

  9. Biomimetics on seed dispersal: survey and insights for space exploration

    International Nuclear Information System (INIS)

    Pandolfi, Camilla; Izzo, Dario

    2013-01-01

    Seeds provide the vital genetic link and dispersal agent between successive generations of plants. Without seed dispersal as a means of reproduction, many plants would quickly die out. Because plants lack any sort of mobility and remain in the same spot for their entire lives, they rely on seed dispersal to transport their offspring throughout the environment. This can be accomplished either collectively or individually; in any case as seeds ultimately abdicate their movement, they are at the mercy of environmental factors. Thus, seed dispersal strategies are characterized by robustness, adaptability, intelligence (both behavioral and morphological), and mass and energy efficiency (including the ability to utilize environmental sources of energy available): all qualities that advanced engineering systems aim at in general, and in particular those that need to enable complex endeavors such as space exploration. Plants evolved and adapted their strategy according to their environment, and taken together, they enclose many desirable characteristics that a space mission needs to have. Understanding in detail how plants control the development of seeds, fabricate structural components for their dispersal, build molecular machineries to keep seeds dormant up to the right moment and monitor the environment to release them at the right time could provide several solutions impacting current space mission design practices. It can lead to miniaturization, higher integration and packing efficiency, energy efficiency and higher autonomy and robustness. Consequently, there would appear to be good reasons for considering biomimetic solutions from plant kingdom when designing space missions, especially to other celestial bodies, where solid and liquid surfaces, atmosphere, etc constitute and are obviously parallel with the terrestrial environment where plants evolved. In this paper, we review the current state of biomimetics on seed dispersal to improve space mission design

  10. Forest rodents provide directed dispersal of Jeffrey pine seeds

    Science.gov (United States)

    Briggs, J.S.; Wall, S.B.V.; Jenkins, S.H.

    2009-01-01

    Some species of animals provide directed dispersal of plant seeds by transporting them nonrandomly to microsites where their chances of producing healthy seedlings are enhanced. We investigated whether this mutualistic interaction occurs between granivorous rodents and Jeffrey pine (Pinus jeffreyi) in the eastern Sierra Nevada by comparing the effectiveness of random abiotic seed dispersal with the dispersal performed by four species of rodents: deer mice (Peromyscus maniculatus), yellow-pine and long-eared chipmunks (Tamias amoenus and T. quadrimaculatus), and golden-mantled ground squirrels (Spermophilus lateralis). We conducted two caching studies using radio-labeled seeds, the first with individual animals in field enclosures and the second with a community of rodents in open forest. We used artificial caches to compare the fates of seeds placed at the range of microsites and depths used by animals with the fates of seeds dispersed abiotically. Finally, we examined the distribution and survival of naturally establishing seedlings over an eight-year period.Several lines of evidence suggested that this community of rodents provided directed dispersal. Animals preferred to cache seeds in microsites that were favorable for emergence or survival of seedlings and avoided caching in microsites in which seedlings fared worst. Seeds buried at depths typical of animal caches (5–25 mm) produced at least five times more seedlings than did seeds on the forest floor. The four species of rodents differed in the quality of dispersal they provided. Small, shallow caches made by deer mice most resembled seeds dispersed by abiotic processes, whereas many of the large caches made by ground squirrels were buried too deeply for successful emergence of seedlings. Chipmunks made the greatest number of caches within the range of depths and microsites favorable for establishment of pine seedlings. Directed dispersal is an important element of the population dynamics of Jeffrey pine, a

  11. Gastropod seed dispersal: an invasive slug destroys far more seeds in its gut than native gastropods.

    Science.gov (United States)

    Blattmann, Tamara; Boch, Steffen; Türke, Manfred; Knop, Eva

    2013-01-01

    Seed dispersal is one of the most important mechanisms shaping biodiversity, and animals are one of the key dispersal vectors. Animal seed dispersal can directly or indirectly be altered by invasive organisms through the establishment of new or the disruption of existing seed dispersal interactions. So far it is known for a few gastropod species that they ingest and defecate viable plant seeds and consequently act as seed dispersers, referred to as gastropodochory. In a multi-species experiment, consisting of five different plant species and four different gastropod species, we tested with a fully crossed design whether gastropodochory is a general mechanism across native gastropod species, and whether it is altered by the invasive alien slug species Arion lusitanicus. Specifically, we hypothesized that a) native gastropod species consume the seeds from all tested plant species in equal numbers (have no preference), b) the voracious invasive alien slug A. lusitanicus--similarly to its herbivore behaviour--consumes a higher amount of seeds than native gastropods, and that c) seed viability is equal among different gastropod species after gut passage. As expected all tested gastropod species consumed all tested plant species. Against our expectation there was a difference in the amount of consumed seeds, with the largest and native mollusk Helix pomatia consuming most seeds, followed by the invasive slug and the other gastropods. Seed damage and germination rates did not differ after gut passage through different native species, but seed damage was significantly higher after gut passage through the invasive slug A. lusitanicus, and their germination rates were significantly reduced.

  12. Tamarind tree seed dispersal by ring-tailed lemurs.

    Science.gov (United States)

    Mertl-Millhollen, Anne S; Blumenfeld-Jones, Kathryn; Raharison, Sahoby Marin; Tsaramanana, Donald Raymond; Rasamimanana, Hantanirina

    2011-10-01

    In Madagascar, the gallery forests of the south are among the most endangered. Tamarind trees (Tamarindus indica) dominate these riverine forests and are a keystone food resource for ring-tailed lemurs (Lemur catta). At Berenty Reserve, the presence of tamarind trees is declining, and there is little recruitment of young trees. Because mature tamarinds inhibit growth under their crowns, seeds must be dispersed away from adult trees if tree recruitment is to occur. Ring-tailed lemurs are likely seed dispersers; however, because they spend much of their feeding, siesta, and sleeping time in tamarinds, they may defecate a majority of the tamarind seeds under tamarind trees. To determine whether they disperse tamarind seeds away from overhanging tamarind tree crowns, we observed two troops for 10 days each, noted the locations of feeding and defecation, and collected seeds from feces and fruit for germination. We also collected additional data on tamarind seedling recruitment under natural conditions, in which seedling germination was abundant after extensive rain, including under the canopy. However, seedling survival to 1 year was lower when growing under mature tamarind tree crowns than when growing away from an overhanging crown. Despite low fruit abundance averaging two fruits/m(3) in tamarind crowns, lemurs fed on tamarind fruit for 32% of their feeding samples. Daily path lengths averaged 1,266 m, and lemurs deposited seeds throughout their ranges. Fifty-eight percent of the 417 recorded lemur defecations were on the ground away from overhanging tamarind tree crowns. Tamarind seeds collected from both fruit and feces germinated. Because lemurs deposited viable seeds on the ground away from overhanging mature tamarind tree crowns, we conclude that ring-tailed lemurs provide tamarind tree seed dispersal services.

  13. Gibbons (Nomascus gabriellae) provide key seed dispersal for the Pacific walnut (Dracontomelon dao), in Asia's lowland tropical forest

    Science.gov (United States)

    Hai, Bach Thanh; Chen, Jin; McConkey, Kim R.; Dayananda, Salindra K.

    2018-04-01

    Understanding the mutualisms between frugivores and plants is essential for developing successful forest management and conservation strategies, especially in tropical rainforests where the majority of plants are dispersed by animals. Gibbons are among the most effective seed dispersers in South East Asia's tropical forests, but are also one of the highly threatened arboreal mammals in the region. Here we studied the seed dispersal of the Pacific walnut (Dracontomelon dao), a canopy tree which produces fruit that are common in the diet of the endangered southern yellow-cheeked crested gibbon (Nomascus gabriellae). We found that gibbons were the most effective disperser for this species; they consumed approximately 45% of the fruit crop, which was four times more than that consumed by macaques - the only other legitimate disperser. Gibbons tracked the temporal (but not spatial) abundance of ripe fruits, indicating this fruit was a preferred species for the gibbon. Both gibbons and macaques dispersed the majority (>90%) of the seeds at least 20 m away from parent crowns, with mean dispersal distances by gibbons measuring 179.3 ± 98.0 m (range: 4-425 m). Seeds defecated by gibbons germinated quicker and at greater rates than seeds spat by macaques, or in undispersed fruits. Gibbon-dispersed seeds were also more likely to be removed by unknown seed predators or unknown secondary dispersers. Overall, gibbons play a key role in the regeneration of the Pacific walnut. Our findings have significant implications both for the management of the Pacific walnut tree dominating tropical rainforest as well as the reintroduction program of the Southern yellow-cheeked crested gibbon.

  14. Endozoochorous seed dispersal by Japanese macaques (Macaca fuscata): Effects of temporal variation in ranging and seed characteristics on seed shadows.

    Science.gov (United States)

    Tsuji, Yamato; Morimoto, Mayumi

    2016-02-01

    Variation in seed shadows generated by frugivores is caused by daily, seasonal, and inter-annual variation in ranging, as well as inter-specific variability in gut passage times according to seed characteristics. We studied the extent to which seed weight, specific gravity, and daily (morning, afternoon, and evening) and inter-annual (2004 vs. 2005) variation in ranging affected seed shadows generated by wild Japanese macaques (Macaca fuscata) in northern Japan. The macaques ingested fleshy fruits of 11 species during the two year study period; Viburnum dilatatum (Caprifoliaceae: heavier seeds with higher specific gravity) and Rosa multiflora (Rosaceae: lighter seeds with lower specific gravity) were eaten frequently in both years. The travel distances of macaques after feeding on V. dilatatum and R. multiflora fruits were estimated by combining feeding locations and ranging patterns measured in the field with gut passage times of model seeds in captive animals. Median travel distances after fruit feeding were 431 (quantile range: 277-654) and 478 m (265-646), respectively, with a maximum of 1,261 m. Neither year nor time of day affected travel distances. The gut passage time of model V. dilatatum seeds was longer than that of model R. multiflora seed, but this did not affect dispersal distances. Seed shadows for both species over 2 years showed unimodal distribution (peak: 101-500 m) and more than 90%, 20%, and 3% of ingested seeds were estimated to be dispersed >100, >500, and >1000 m, respectively, the longest known distances among macaque species. R. multiflora seeds tended to be dispersed further in 2004 than 2005, but V. dilatatum seeds were not, implying that inter-annual variations in ranging pattern due to the distribution and abundance of nut fruiting could affect dispersal distance. © 2015 Wiley Periodicals, Inc.

  15. Overseas seed dispersal by migratory birds

    NARCIS (Netherlands)

    Viana, D.S.; Gangoso, L.; Bouten, W.; Figuerola, J.

    2016-01-01

    Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has

  16. Contagious deposition of seeds in spider monkeys' sleeping trees limits effective seed dispersal in fragmented landscapes.

    Directory of Open Access Journals (Sweden)

    Arturo González-Zamora

    Full Text Available The repeated use of sleeping sites by frugivorous vertebrates promotes the deposition and aggregation of copious amounts of seeds in these sites. This spatially contagious pattern of seed deposition has key implications for seed dispersal, particularly because such patterns can persist through recruitment. Assessing the seed rain patterns in sleeping sites thus represents a fundamental step in understanding the spatial structure and regeneration of plant assemblages. We evaluated the seed rain produced by spider monkeys (Ateles geoffroyi in latrines located beneath 60 sleeping trees in two continuous forest sites (CFS and three forest fragments (FF in the Lacandona rainforest, Mexico. We tested for differences among latrines, among sites, and between forest conditions in the abundance, diversity (α-, β- and, γ-components and evenness of seed assemblages. We recorded 45,919 seeds ≥ 5 mm (in length from 68 species. The abundance of seeds was 1.7 times higher in FF than in CFS, particularly because of the dominance of a few plant species. As a consequence, community evenness tended to be lower within FF. β-diversity of common and dominant species was two times greater among FF than between CFS. Although mean α-diversity per latrine did not differ among sites, the greater β-diversity among latrines in CFS increased γ-diversity in these sites, particularly when considering common and dominant species. Our results support the hypothesis that fruit scarcity in FF can 'force' spider monkeys to deplete the available fruit patches more intensively than in CFS. This feeding strategy can limit the effectiveness of spider monkeys as seed dispersers in FF, because (i it can limit the number of seed dispersers visiting such fruit patches; (ii it increases seed dispersal limitation; and (iii it can contribute to the floristic homogenization (i.e., reduced β-diversity among latrines in fragmented landscapes.

  17. Emergence of ratio-dependent and predator-dependent functional responses for pollination mutualism and seed parasitism

    Science.gov (United States)

    DeAngelis, Donald L.; Holland, J. Nathaniel

    2006-01-01

    Prey (N) dependence [g(N)], predator (P) dependence [g(P) or g(N,P)], and ratio dependence [f(P/N)] are often seen as contrasting forms of the predator's functional response describing predator consumption rates on prey resources in predator–prey and parasitoid–host interactions. Analogously, prey-, predator-, and ratio-dependent functional responses are apparently alternative functional responses for other types of consumer–resource interactions. These include, for example, the fraction of flowers pollinated or seeds parasitized in pollination (pre-dispersal) seed-parasitism mutualisms, such as those between fig wasps and fig trees or yucca moths and yucca plants. Here we examine the appropriate functional responses for how the fraction of flowers pollinated and seeds parasitized vary with the density of pollinators (predator dependence) or the ratio of pollinator and flower densities (ratio dependence). We show that both types of functional responses can emerge from minor, but biologically important variations on a single model. An individual-based model was first used to describe plant–pollinator interactions. Conditional upon on whether the number of flowers visited by the pollinator was limited by factors other than search time (e.g., by the number of eggs it had to lay, if it was also a seed parasite), and on whether the pollinator could directly find flowers on a plant, or had to search, the simulation results lead to either a predator-dependent or a ratio-dependent functional response. An analytic model was then used to show mathematically how these two cases can arise.

  18. Myrmecochory by small ants - Beneficial effects through elaiosome nutrition and seed dispersal

    Science.gov (United States)

    Fokuhl, Gerriet; Heinze, Jürgen; Poschlod, Peter

    2012-01-01

    Seed dispersal by ants (myrmecochory) is a common mutualism in temperate woodlands of the Northern hemisphere. In this paper we highlight the contribution of one of the most abundant ant species of Eastern Central Europe, Temnothorax crassispinus, to myrmecochory. In field and mesocosm studies we found that T. crassispinus workers disperse seeds over distances of up to 162 cm and carry them to their nests, thereby enabling the spread of Chelidonium majus seedlings. In a controlled feeding experiment with four different feeding regimes, we supplemented the respective diet of a fraction of the nests with the elaiosome-bearing seeds of C. majus and Scilla bifolia. Here, ant workers carried seeds to their nest and fed elaiosome pieces to their larvae. Subsequent production of sexual offspring and dry weights of sexual pupae were positively correlated with increasing feeding frequencies. With supplementary elaiosome feeding, the female dry weight was significantly higher, whereas the male dry weight decreased. Our results indicate a nutritional benefit from elaiosomes to the ants, which may cause shifts of investment, and at the same time underline the ecological relevance of Temnothorax ants for elaiosome-bearing plants.

  19. Complementary roles of two resilient neotropical mammalian seed dispersers

    Science.gov (United States)

    de Almeida, Adriana; Morris, Rebecca J.; Lewis, Owen T.; Mikich, Sandra B.

    2018-04-01

    Capuchin monkeys (Cebus spp. and Sapajus spp.) and coatis (Nasua spp.) coexist in most neotropical forests, including small forest remnants. Both capuchins and coatis eat fruit and disperse seeds, but little is known about whether their roles in seed dispersal are redundant or complementary. We compiled 49 studies from the literature on feeding by capuchins and/or coatis, of which 19 were comprehensive enough for our analyses. We determined the relative importance of fruit eating to each species and compared their diets. Additionally, we analysed the structure of three fruit-frugivore networks built with both animal groups and the fruits they eat and evaluated whether fruit traits influenced the network topology. Fruits represented the largest part of capuchin and coati diets, even though coatis have been known for their opportunistic and generalist diets. Capuchins and coatis also exhibited similar general diet parameters (niche breadth and trophic diversity). The three networks exhibited high connectance values and variable niche overlap. A Multiple Correspondence Analysis, failed to detect any trait or trait combination related to food use. In conclusion, capuchins and coatis both have generalist diets; they feed on many different species of fruits and exhibit important complementarity as seed dispersers. Both are likely to be particularly important seed dispersers in disturbed and fragmented forests.

  20. Seed dispersal by vertebrates in Madagascar's forests: review and ...

    African Journals Online (AJOL)

    Madagascar's highly diverse forests are critically threatened because of increasing deforestation, and those that remain are facing declines of vertebrate frugivores that disperse their seeds. Thus, understanding plant - frugivore interactions is of critical importance for the conservation and maintenance of plant diversity in ...

  1. Busy Nights: High Seed Dispersal by Crickets in a Neotropical Forest.

    Science.gov (United States)

    Santana, Flávia Delgado; Baccaro, Fabricio Beggiato; Costa, Flávia Regina Capellotto

    2016-11-01

    Among invertebrates, ants are the most abundant and probably most important seed dispersers in both temperate and tropical environments. Crickets, also abundant in tropical forests, are omnivores and commonly attracted to fruits on the forest floor. However, their capability to remove seeds has been reported only once. We compared Marantaceae seed removal by crickets and ants to assess the role of crickets as secondary seed dispersers in Amazonia. Compared with ants, crickets dispersed an equivalent number of seeds and tended to disperse larger seeds farther. However, seed removal by crickets occurs mostly at night, suggesting that removal of arillate seeds by crickets on the tropical forest floor is probably being overlooked or wrongly attributed to other invertebrate groups. One potential consequence of seed dispersal by crickets may be a change in the local spatial distribution of arillate-seed species, due to lower aggregation around ant nests.

  2. Combining distances of ballistic and myrmecochorous seed dispersal in Adriana quadripartita (Euphorbiaceae)

    Science.gov (United States)

    Beaumont, Kieren P.; Mackay, Duncan A.; Whalen, Molly A.

    2009-05-01

    The separate contributions of different vectors to net seed dispersal curves of diplochorous systems have rarely been characterised. In Australia, myrmecochory is a common seed dispersal syndrome and in the majority of such systems, seeds are initially dispersed ballistically. We measured ballistic and myrmecochorous seed dispersal distances in relation to canopies of Adriana quadripartita (Euphorbiaceae) and used a simulation model to estimate the net dispersal curve. We also compared seed removal rates and ant abundances under, and outside, plant canopies to examine how foraging patterns by ants may affect net dispersal. Overall ant abundance did not show a significant numerical response to seedfall; however, the abundance of the main seed dispersing ant, Rhytidoponera 'metallica' did. Despite this, seed removal rates did not differ significantly between canopy and open locations. Rhytidoponera 'metallica' account for 93% of observed seed dispersal events. On average, the ants dispersed seeds 1.54 m and in doing so, moved seed a mean radial distance of 0.76 m away from canopy edges. This contribution to net dispersal distance by ants is considerable since ballistic dispersal moved seeds a median distance of 7.5 cm. Our simulation model indicated that the combination of ballistic and ant seed dispersal is expected to result in seeds being transported a median net radial dispersal distance of 1.05 m from the canopy edge. Thus in this system, an important function of diplochory may simply be to move a higher proportion of seeds from under the canopy of parent plants than is possible by ballistic dispersal alone. This 'dispersal-for-distance' may result in reduced parent-offspring competition or may increase the probability that seeds reach rare safe sites for germination and recruitment.

  3. The Effect of Height, Wing Length, and Wing Symmetry on Tabebuia rosea Seed Dispersal

    Directory of Open Access Journals (Sweden)

    Yasmeen Moussa

    2014-12-01

    Full Text Available The relationship between the vertical drop height and the horizontal distance traveled (dispersal ratio was investigated for a sample of fifty Tabebuia rosea seeds by dropping the seeds from five heights ranging from 1.00 to 2.00 meters. The dispersal ratio was found to be a constant 0.16 m/m for these heights. The effects of total seed length and asymmetry of seed wings on dispersal ratio were also measured using separate samples of fifty Tabebuia rosea seeds. It was found that neither seed length nor asymmetry had a significant effect on the dispersal ratio.

  4. Effectiveness of primate seed dispersers for an "oversized" fruit, Garcinia benthamii.

    Science.gov (United States)

    McConkey, Kim R; Brockelman, Warren Y; Saralamba, Chanpen; Nathalang, Anuttara

    2015-10-01

    The largest fruits found in tropical forests may depend on complementary seed dispersal strategies. These fruits are dispersed most effectively by megafauna, but populations can persist where megafauna are absent or erratic visitors. Smaller animals often consume these large fruits, but their capacity to disperse these seeds effectively has rarely been assessed. We evaluated the contributions of gibbons (Hylobates lar) and other frugivores in the seed dispersal of the megafaunal fruit Garcinia benthamii, using the SDE (seed dispersal effectiveness) landscape. Gibbons preferentially consumed G. benthamii fruits and were the main seed disperser that we observed. However, gibbons became satiated when availability was high, with 57% of fruits falling to the ground unhandled. Recruitment of seedlings from gibbon-dispersed seeds was also very low. Elephants consumed G. benthamii fruit, but occurred at low density and were rare visitors to the trees. We suggest that gibbons might complement the seed dispersal role of elephants for G. benthamii, allowing limited recruitment in areas (such as the study site) where elephants occur at low density. Fruit availability varied between years; when availability was low, gibbons reliably consumed most of the crop and dispersed some seeds that established seedlings, albeit at low numbers (2.5 seedlings per crop). When fruit availability was high, the fruit supply overwhelmed the gibbons and other arboreal frugivores, ensuring a large abundance of fruit available to terrestrial seed dispersers. Although gibbons effectively dispersed more seeds at these times (20.7 seedlings per crop), there was the potential for elephants to move many more seeds. Complementary seed dispersal strategies may be important for megafaunal fruit, because they ensure that very large fruits are able to benefit from megafaunal dispersal but also persist where this dispersal becomes erratic. However, our data suggest that smaller seed dispersers might not be

  5. Seed drops and caches by the harvester ant Messor barbarus: do they contribute to seed dispersal in Mediterranean grasslands?

    Science.gov (United States)

    Detrain, C.; Tasse, Olivier

    To determine whether the harvester ant Messor barbarus acts as a seed disperser in Mediterranean grasslands, the accuracy level of seed processing was assessed in the field by quantifying seed drops by loaded foragers. In the vicinity of exploited seed patches 3times as many diaspores were found as in controls due to seed losses by foragers. Over trails, up to 30% of harvested seeds were dropped, singly, by workers but all were recovered by nestmates within 24h. Seeds were also dropped within temporary caches with very few viable diaspores being left per cache when ants no longer used the trail. Globally, ant-dispersed diaspores accounted for only 0.1% of seeds harvested by M. barbarus. We discuss the possible significance for grassland vegetation of harvester-ant-mediated seed dispersal.

  6. Geographic variations in seed dispersal by ants: are plant and seed traits decisive?

    Science.gov (United States)

    Boulay, R.; Coll-Toledano, J.; Manzaneda, A. J.; Cerdá, X.

    2007-03-01

    The effect of local ant species on the dispersal success of a myrmecochorous plant, Helleborus foetidus, was analyzed in two populations of the Iberian Peninsula (Caurel and Cazorla, respectively). The contribution of the various local ant species to dispersal was very unequal. While 5 and 19 ant taxa visited the plants of Caurel and Cazorla, respectively, most removal activity (67 and 80%) was performed by two species only (Formica lugubris and Camponotus cruentatus, respectively). Visits by dispersers were also unequally distributed between neighboring plants. While some plants were always visited during the period of seed release, others were never visited. A regression model indicated that this pattern might be explained by two plant traits: ants preferred to visit plants that released more seeds and whose elaiosomes were richer in oleic acid. Although it has long been known that this compound triggers removal by ants, it is the first demonstration that quantitative variations in elaiosome traits contribute to variation in dispersal success. Finally, other variables being equal, morphological traits (seed size, elaiosome size, and elaiosome/seed size ratio) did not affect ant behavior. Although myrmecochory has long been considered a diffuse interaction, our results support the idea that, at local scale, a limited number of ant species may be decisive to its evolution.

  7. Evaluating the potential for weed seed dispersal based on waterfowl consumption and seed viability.

    Science.gov (United States)

    Farmer, Jaime A; Webb, Elisabeth B; Pierce, Robert A; Bradley, Kevin W

    2017-12-01

    Migratory waterfowl have often been implicated in the movement of troublesome agronomic and wetland weed species. However, minimal research has been conducted to investigate the dispersal of agronomically important weed species by waterfowl. The two objectives for this project were to determine what weed species are being consumed by ducks and snow geese, and to determine the recovery rate and viability of 13 agronomic weed species after passage through a duck's digestive system. Seed recovered from digestive tracts of 526 ducks and geese harvested during a 2-year field study had 35 020 plants emerge. A greater variety of plant species emerged from ducks each year (47 and 31 species) compared to geese (11 and 3 species). Viable seed from 11 of 13 weed species fed to ducks in a controlled feeding study were recovered. Viability rate and gut retention times indicated potential dispersal up to 2900 km from the source depending on seed characteristics and variability in waterfowl dispersal distances. Study results confirm that waterfowl are consuming seeds from a variety of agronomically important weed species, including Palmer amaranth, which can remain viable after passage through digestive tracts and have potential to be dispersed over long distances by waterfowl. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  8. Frugivory and seed dispersal by vertebrates in tropical and subtropical Asia: An update

    OpenAIRE

    Richard T. Corlett

    2017-01-01

    Seed dispersal is a key process in plant communities and frugivory is very important in vertebrate communities. This paper updates a review of frugivory and seed dispersal by vertebrates in the Oriental Region (tropical and subtropical Asia) published in 1998. The major conclusions remain the same. Small fruits are consumed by a wide range of potential seed dispersal agents, including species that thrive in small forest fragments and degraded landscapes. Larger and larger-seeded fruits are co...

  9. Seed dispersal by the Florida box turtle (Terrapene carolina bauri) in pine rockland forests of the lower Florida Keys, United States.

    Science.gov (United States)

    Liu, Hong; Platt, Steven G; Borg, Christopher K

    2004-03-01

    Seed dispersal by animals is one of the most important plant-animal mutualisms, but saurochory, the dispersal of seeds by reptiles, has received little attention. We investigated the role of the Florida box turtle (Terrapene carolina bauri) as a seed dispersal agent in pine rockland forests of the lower Florida Keys and examined the effect of turtle digestion on seed germination. We obtained seeds of 11 species with fleshy fruits and 2 species with non-fleshy fruits (a grass and legume) from the feces of 145 box turtles collected on Key Deer National Wildlife Refuge from 1999 to 2000. We planted the seeds of nine species and germination percentage (percentage of seeds that germinated during the experiment) varied from 10% to 80%. Comparative germination experiments were conducted with Thrinax morrissii, Serenoa repens, and Byrsonima lucida. We compared the germination percentage and germination rate (number of days from planting to seedling emergence) of seeds from three treatments (seeds recovered from feces, control seeds with pulp, and control seeds without pulp) and continued these experiments for up to 2 years. Passage through the box turtle digestive tract greatly enhanced the germination percentage and germination rate of S. repens, but decreased the germination percentage of B. lucida and T. morrissii, and decreased germination rate for T. morrissii. Subsequent destructive seed viability tests revealed that many ungerminated T. morrissii seeds remained viable, suggesting long-term seed dormancy may occur, even after passage through the turtle digestive system. In addition, the proportion of ungerminated seeds which remained viable was greater for seeds recovered from turtle feces than from control seeds with pulp. Furthermore, removal of fleshy pulp either manually or by the turtle digestive system may allow T. morrissii to escape insect predation.

  10. Seed dispersal in six species of terrestrial orchids in Biebrza National Park (NE Poland

    Directory of Open Access Journals (Sweden)

    Emilia Brzosko

    2017-09-01

    Full Text Available Knowledge about seed dispersal is required to explain problems in ecology, phylogeography, and conservation biology. Even though seed dispersal is a fundamental mechanism to understand problems at different levels of biological organization (individual, population, species, landscape, it remains one of the least recognized processes. Similar to other groups of plants, very little is known regarding patterns and distances of seed dispersal in orchids. Orchid seeds are generally assumed to be widely dispersed by wind because of their small size and low weight. Between 2006 and 2008, we conducted a field study of the distances at which orchid seeds are dispersed, and determined factors affecting dispersal. Investigations included 13 populations of six terrestrial orchid species – Cypripedium calceolus, Cephalanthera rubra, Epipactis helleborine, Goodyera repens, Neottia ovata, and Platanthera bifolia. To evaluate seed dispersal in orchid populations, 8.5-cm Petri dishes (traps with self-adhesive paper were placed along transects, starting from a group of fruiting plants, which were considered to be the dispersal source. Seeds of the investigated orchid species were dispersed over relatively short distances. There were statistically significant negative correlations between seed density and distance from the fruiting plants. Seeds of species with taller fruiting shoots were dispersed farther than those with shorter ones (R = 0.68, p < 0.05. We discuss the causes and consequences of the dispersal patterns of orchid seeds.

  11. DNA fingerprinting validates seed dispersal curves from observational studies in the neotropical legume parkia.

    Science.gov (United States)

    Heymann, Eckhard W; Lüttmann, Kathrin; Michalczyk, Inga M; Saboya, Pedro Pablo Pinedo; Ziegenhagen, Birgit; Bialozyt, Ronald

    2012-01-01

    Determining the distances over which seeds are dispersed is a crucial component for examining spatial patterns of seed dispersal and their consequences for plant reproductive success and population structure. However, following the fate of individual seeds after removal from the source tree till deposition at a distant place is generally extremely difficult. Here we provide a comparison of observationally and genetically determined seed dispersal distances and dispersal curves in a Neotropical animal-plant system. In a field study on the dispersal of seeds of three Parkia (Fabaceae) species by two Neotropical primate species, Saguinus fuscicollis and Saguinus mystax, in Peruvian Amazonia, we observationally determined dispersal distances. These dispersal distances were then validated through DNA fingerprinting, by matching DNA from the maternally derived seed coat to DNA from potential source trees. We found that dispersal distances are strongly right-skewed, and that distributions obtained through observational and genetic methods and fitted distributions do not differ significantly from each other. Our study showed that seed dispersal distances can be reliably estimated through observational methods when a strict criterion for inclusion of seeds is observed. Furthermore, dispersal distances produced by the two primate species indicated that these primates fulfil one of the criteria for efficient seed dispersers. Finally, our study demonstrated that DNA extraction methods so far employed for temperate plant species can be successfully used for hard-seeded tropical plants.

  12. Seed dispersal of the Australian cycad Macrozamia miquelii (Zamiaceae): are cycads megafauna-dispersed "grove forming" plants?

    Science.gov (United States)

    Hall, John A; Walter, Gimme H

    2013-06-01

    Plants that invest in large, heavy seeds and colorful, fleshy fruits or analogous structures seem adapted for dispersal by large vertebrates. Some such plants, like Australian cycads in the genus Macrozamia, do not disperse well, which could be explained by seed-dispersal relationships with megafauna that are rare or extinct in contemporary ecosystems. Such plants provide an opportunity to investigate the ecological consequences of low seed-dispersal distances. • We investigated seed dispersal of Macrozamia miquelii in Central Queensland by tracking the fate of marked seeds, identifying the dispersal fauna and quantifying population demography and spatial structure. • We found that 70-100% of marked seeds remained within 1 m of maternal females (cycads are dioecious). Of the 812 seeds recovered (from 840 originally marked) only 24 dispersed >1 m from maternal females, the greatest observed dispersal being 5 m. We found an average of 2.2 seedlings and 0.7 juveniles within 1.5 m of mature females, which suggests that most seeds that remain in the vicinity of maternal females perish. Within-stand densities ranged between 1000 and 5000 plants/ha. The brushtail possum Trichosurus vulpecula was the only animal observed to move the seeds. • Macrozamia are adapted for dispersal by megafauna that are rare or absent in contemporary ecosystems. We argue that Macrozamia are "grove forming" plants that derive ecological benefit from existing as high-density, spatially discrete populations, the function of megafaunal dispersal adaptations being the infrequent dispersal of seeds en masse to establish new such groves in the landscape.

  13. Human-mediated dispersal of seeds by the airflow of vehicles.

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    von der Lippe, Moritz; Bullock, James M; Kowarik, Ingo; Knopp, Tatjana; Wichmann, Matthias C; Wichmann, Matthias

    2013-01-01

    Human-mediated dispersal is known as an important driver of long-distance dispersal for plants but underlying mechanisms have rarely been assessed. Road corridors function as routes of secondary dispersal for many plant species but the extent to which vehicles support this process remains unclear. In this paper we quantify dispersal distances and seed deposition of plant species moved over the ground by the slipstream of passing cars. We exposed marked seeds of four species on a section of road and drove a car along the road at a speed of 48 km/h. By tracking seeds we quantified movement parallel as well as lateral to the road, resulting dispersal kernels, and the effect of repeated vehicle passes. Median distances travelled by seeds along the road were about eight meters for species with wind dispersal morphologies and one meter for species without such adaptations. Airflow created by the car lifted seeds and resulted in longitudinal dispersal. Single seeds reached our maximum measuring distance of 45 m and for some species exceeded distances under primary dispersal. Mathematical models were fit to dispersal kernels. The incremental effect of passing vehicles on longitudinal dispersal decreased with increasing number of passes as seeds accumulated at road verges. We conclude that dispersal by vehicle airflow facilitates seed movement along roads and accumulation of seeds in roadside habitats. Dispersal by vehicle airflow can aid the spread of plant species and thus has wide implications for roadside ecology, invasion biology and nature conservation.

  14. Defaunation leads to interaction deficits, not interaction compensation, in an island seed dispersal network.

    Science.gov (United States)

    Fricke, Evan C; Tewksbury, Joshua J; Rogers, Haldre S

    2018-01-01

    Following defaunation, the loss of interactions with mutualists such as pollinators or seed dispersers may be compensated through increased interactions with remaining mutualists, ameliorating the negative cascading impacts on biodiversity. Alternatively, remaining mutualists may respond to altered competition by reducing the breadth or intensity of their interactions, exacerbating negative impacts on biodiversity. Despite the importance of these responses for our understanding of the dynamics of mutualistic networks and their response to global change, the mechanism and magnitude of interaction compensation within real mutualistic networks remains largely unknown. We examined differences in mutualistic interactions between frugivores and fruiting plants in two island ecosystems possessing an intact or disrupted seed dispersal network. We determined how changes in the abundance and behavior of remaining seed dispersers either increased mutualistic interactions (contributing to "interaction compensation") or decreased interactions (causing an "interaction deficit") in the disrupted network. We found a "rich-get-richer" response in the disrupted network, where remaining frugivores favored the plant species with highest interaction frequency, a dynamic that worsened the interaction deficit among plant species with low interaction frequency. Only one of five plant species experienced compensation and the other four had significant interaction deficits, with interaction frequencies 56-95% lower in the disrupted network. These results do not provide support for the strong compensating mechanisms assumed in theoretical network models, suggesting that existing network models underestimate the prevalence of cascading mutualism disruption after defaunation. This work supports a mutualist biodiversity-ecosystem functioning relationship, highlighting the importance of mutualist diversity for sustaining diverse and resilient ecosystems. © 2017 John Wiley & Sons Ltd.

  15. Dispersal pathways, seed rains, and the dynamics of larval behavior.

    Science.gov (United States)

    Zimmer, Richard K; Fingerut, Jonathan T; Zimmer, Cheryl Ann

    2009-07-01

    Dispersing propagules (larvae, seeds, and spores) establish and maintain populations, which serve as templates for subsequent species interactions. Connectivity among demes derives, in large part, from connectivity between consecutive steps, release, transport, and settlement, in dispersal pathways. Concurrent measurements of individuals in each step are a necessary precursor to identifying governing mechanisms. Here we directly and definitively resolved the roles of physics and behavior in mediating dispersal pathways of an estuarine parasite between its intermediate hosts. Planktonic cercariae of Himasthla rhigedana, a parasitic flatworm, are functionally similar to lecithotrophic larvae of many free-living marine invertebrates. The combination of parasite life cycle characteristics and the relatively simple tidal flows in their habitat renders this system an effective model for dispersal studies. Simultaneous field measurements of larval release, transport, settlement, and the flow regime, together with mechanistic experiments, led to empirical understanding of host colonization. All dispersal steps were highly and significantly correlated over time and in space. This tight coupling resulted, unequivocally, from a suite of larval behaviors. Cercariae emerged from first intermediate host snails only during daytime flood tides, enhancing larval retention in the marsh. Daylight triggered downward swimming, and within seconds, cercariae overpowered turbulent mixing, landing in benthic habitat of second intermediate host snails and crabs. Larvae settled (encysted) on external regions of snails/crabs that, presumably, were most vulnerable to ingestion by definitive host shorebirds. In total, cercarial behaviors greatly foreshortened dispersal distances, magnified local parasite prevalence, and increased the likelihood of large-scale transmission by definitive hosts. Cracking open the black box of dispersal thus revealed mechanisms, connectivity, and ecological

  16. Divergent chemical cues elicit seed collecting by ants in an obligate multi-species mutualism in lowland Amazonia.

    Directory of Open Access Journals (Sweden)

    Elsa Youngsteadt

    2010-12-01

    Full Text Available In lowland Amazonian rainforests, specific ants collect seeds of several plant species and cultivate them in arboreal carton nests, forming species-specific symbioses called ant-gardens (AGs. In this obligate mutualism, ants depend on the plants for nest stability and the plants depend on ant nests for substrate and nutrients. AG ants and plants are abundant, dominant members of lowland Amazonian ecosystems, but the cues ants use to recognize the seeds are poorly understood. To address the chemical basis of the ant-seed interaction, we surveyed seed chemistry in nine AG species and eight non-AG congeners. We detected seven phenolic and terpenoid volatiles common to seeds of all or most of the AG species, but a blend of the shared compounds was not attractive to the AG ant Camponotus femoratus. We also analyzed seeds of three AG species (Anthurium gracile, Codonanthe uleana, and Peperomia macrostachya using behavior-guided fractionation. At least one chromatographic fraction of each seed extract elicited retrieval behavior in C. femoratus, but the active fractions of the three plant species differed in polarity and chemical composition, indicating that shared compounds alone did not explain seed-carrying behavior. We suggest that the various AG seed species must elicit seed-carrying with different chemical cues.

  17. Field experiments on seed dispersal by wind in ten umbelliferous species (Apiaceae)

    NARCIS (Netherlands)

    Jongejans, E.; Telenius, A.

    2001-01-01

    This report presents data from experiments on seed dispersal by wind for ten species of the family Apiaceae. Seed shadows were obtained in the field under natural conditions, using wind speeds between four and ten m/s. The flight of individual seeds was followed by eye, and seed shadows were

  18. Seed dispersal and predation of Buchenavia tomentosa Eichler (Combretaceae in a Cerrado sensu stricto, midwest Brazil

    Directory of Open Access Journals (Sweden)

    J. Farias

    Full Text Available Abstract The ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. We investigated seed dispersal aspects associated with the high abundance of Buchenavia tomentosa in the Serra Azul State Park (PESA. We estimated fruit production and conducted fruit removal experiments. We carried out diurnal and nocturnal observations on frugivory as well as germination tests. Fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha–1. B. tomentosa fruits were utilized by eight animal species. The lowland tapir (Tapirus terrestris was considered the main seed disperser. Leafcutter ants (Atta laevigata and Atta sexdens participated in the seed cleaning and occasionally dispersed seeds. The beetle Amblycerus insuturatus, blue-and-yellow macaw (Ara ararauna and red-and-green macaw (Ara chloropterus were considered pre-dispersal seed predators. The seeds manually cleaned presented higher germination rate (100% and speed index (4.2 seeds.d–1 than that of seeds with pulp. Germination of seeds found in tapirs’feces was 40%, while for the seeds without pulp it was 25%. The high abundance of B. tomentosa in the cerrado of PESA may be due to massive fruit production, low rates of seed predation, and efficient seed dispersal by tapirs, occurring before the rains which promote germination and recruitment of this species.

  19. Conflicting selection on diaspore traits limits the evolutionary potential of seed dispersal by ants.

    Science.gov (United States)

    Manzaneda, Antonio J; Rey, P J; Alcántara, J M

    2009-07-01

    Conflicts of selection on diaspore traits throughout the dispersal cycle can limit the evolutionary consequences of seed dispersal. However, these conflicts have never been investigated in directed dispersal systems. We explored conflicts of selection through life stages of dispersal in the myrmecochorous herb Helleborus foetidus. Seeds are subject to two contrasting partial selective scenarios. Undispersed seeds are subject to positive directional selection on seed size characters, whereas seeds dispersed are subject to stabilizing selection for size. In both scenarios, seedling establishment determined the magnitude and direction of selection. This does not reflect ant preferences for seed size. However, total selection still depends largely on ant activity, as ants control the relative importance of each selective scenario. We advocate the use of analytical approaches combining multiplicative fitness and microenvironment-specific selection to more realistically estimate the realized selection on traits functional during several life stages. This approach may be extended to any organism dispersing offspring to different environments.

  20. Mountain-climbing bears protect cherry species from global warming through vertical seed dispersal.

    Science.gov (United States)

    Naoe, Shoji; Tayasu, Ichiro; Sakai, Yoichiro; Masaki, Takashi; Kobayashi, Kazuki; Nakajima, Akiko; Sato, Yoshikazu; Yamazaki, Koji; Kiyokawa, Hiroki; Koike, Shinsuke

    2016-04-25

    In a warming climate, temperature-sensitive plants must move toward colder areas, that is, higher latitude or altitude, by seed dispersal [1]. Considering that the temperature drop with increasing altitude (-0.65°C per 100 m altitude) is one hundred to a thousand times larger than that of the equivalent latitudinal distance [2], vertical seed dispersal is probably a key process for plant escape from warming temperatures. In fact, plant geographical distributions are tracking global warming altitudinally rather than latitudinally, and the extent of tracking is considered to be large in plants with better-dispersed traits (e.g., lighter seeds in wind-dispersed plants) [1]. However, no study has evaluated vertical seed dispersal itself due to technical difficulty or high cost. Here, we show using a stable oxygen isotope that black bears disperse seeds of wild cherry over several hundred meters vertically, and that the dispersal direction is heavily biased towards the mountain tops. Mountain climbing by bears following spring-to-summer plant phenology is likely the cause of this biased seed dispersal. These results suggest that spring- and summer-fruiting plants dispersed by animals may have high potential to escape global warming. Our results also indicate that the direction of vertical seed dispersal can be unexpectedly biased, and highlight the importance of considering seed dispersal direction to understand plant responses to past and future climate change. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Gopherus agassizii (Desert Tortoise). Non-native seed dispersal

    Science.gov (United States)

    Ennen, J.R.; Loughran, Caleb L.; Lovich, Jeffrey E.

    2011-01-01

    Sahara Mustard (Brassica tournefortii) is a non-native, highly invasive weed species of southwestern U.S. deserts. Sahara Mustard is a hardy species, which flourishes under many conditions including drought and in both disturbed and undisturbed habitats (West and Nabhan 2002. In B. Tellman [ed.], Invasive Plants: Their Occurrence and Possible Impact on the Central Gulf Coast of Sonora and the Midriff Islands in the Sea of Cortes, pp. 91–111. University of Arizona Press, Tucson). Because of this species’ ability to thrive in these habitats, B. tournefortii has been able to propagate throughout the southwestern United States establishing itself in the Mojave and Sonoran Deserts in Arizona, California, Nevada, and Utah. Unfortunately, naturally disturbed areas created by native species, such as the Desert Tortoise (Gopherus agassizii), within these deserts could have facilitated the propagation of B. tournefortii. (Lovich 1998. In R. G. Westbrooks [ed.], Invasive Plants, Changing the Landscape of America: Fact Book, p. 77. Federal Interagency Committee for the Management of Noxious and Exotic Weeds [FICMNEW], Washington, DC). However, Desert Tortoises have never been directly observed dispersing Sahara Mustard seeds. Here we present observations of two Desert Tortoises dispersing Sahara Mustard seeds at the interface between the Mojave and Sonoran deserts in California.

  2. Functional redundancy and complementarities of seed dispersal by the last neotropical megafrugivores.

    Science.gov (United States)

    Bueno, Rafael S; Guevara, Roger; Ribeiro, Milton C; Culot, Laurence; Bufalo, Felipe S; Galetti, Mauro

    2013-01-01

    Functional redundancy has been debated largely in ecology and conservation, yet we lack detailed empirical studies on the roles of functionally similar species in ecosystem function. Large bodied frugivores may disperse similar plant species and have strong impact on plant recruitment in tropical forests. The two largest frugivores in the neotropics, tapirs (Tapirus terrestris) and muriquis (Brachyteles arachnoides) are potential candidates for functional redundancy on seed dispersal effectiveness. Here we provide a comparison of the quantitative, qualitative and spatial effects on seed dispersal by these megafrugivores in a continuous Brazilian Atlantic forest. We found a low overlap of plant species dispersed by both muriquis and tapirs. A group of 35 muriquis occupied an area of 850 ha and dispersed 5 times more plant species, and 13 times more seeds than 22 tapirs living in the same area. Muriquis dispersed 2.4 times more seeds in any random position than tapirs. This can be explained mainly because seed deposition by muriquis leaves less empty space than tapirs. However, tapirs are able to disperse larger seeds than muriquis and move them into sites not reached by primates, such as large forest gaps, open areas and fragments nearby. Based on published information we found 302 plant species that are dispersed by at least one of these megafrugivores in the Brazilian Atlantic forest. Our study showed that both megafrugivores play complementary rather than redundant roles as seed dispersers. Although tapirs disperse fewer seeds and species than muriquis, they disperse larger-seeded species and in places not used by primates. The selective extinction of these megafrugivores will change the spatial seed rain they generate and may have negative effects on the recruitment of several plant species, particularly those with large seeds that have muriquis and tapirs as the last living seed dispersers.

  3. Functional redundancy and complementarities of seed dispersal by the last neotropical megafrugivores.

    Directory of Open Access Journals (Sweden)

    Rafael S Bueno

    Full Text Available Functional redundancy has been debated largely in ecology and conservation, yet we lack detailed empirical studies on the roles of functionally similar species in ecosystem function. Large bodied frugivores may disperse similar plant species and have strong impact on plant recruitment in tropical forests. The two largest frugivores in the neotropics, tapirs (Tapirus terrestris and muriquis (Brachyteles arachnoides are potential candidates for functional redundancy on seed dispersal effectiveness. Here we provide a comparison of the quantitative, qualitative and spatial effects on seed dispersal by these megafrugivores in a continuous Brazilian Atlantic forest.We found a low overlap of plant species dispersed by both muriquis and tapirs. A group of 35 muriquis occupied an area of 850 ha and dispersed 5 times more plant species, and 13 times more seeds than 22 tapirs living in the same area. Muriquis dispersed 2.4 times more seeds in any random position than tapirs. This can be explained mainly because seed deposition by muriquis leaves less empty space than tapirs. However, tapirs are able to disperse larger seeds than muriquis and move them into sites not reached by primates, such as large forest gaps, open areas and fragments nearby. Based on published information we found 302 plant species that are dispersed by at least one of these megafrugivores in the Brazilian Atlantic forest.Our study showed that both megafrugivores play complementary rather than redundant roles as seed dispersers. Although tapirs disperse fewer seeds and species than muriquis, they disperse larger-seeded species and in places not used by primates. The selective extinction of these megafrugivores will change the spatial seed rain they generate and may have negative effects on the recruitment of several plant species, particularly those with large seeds that have muriquis and tapirs as the last living seed dispersers.

  4. Differential dispersal of Chamaesyce maculata seeds by two ant species in Japan

    OpenAIRE

    Ohnishi, Yoshihiro K.; Katayama, Noboru; Suzuki, Nobuhiko

    2013-01-01

    Seed dispersal by ants (myrmecochory) is a widely distributed plant-animal interaction in many ecosystems, and it has been regarded as a generalized (multiple species) interaction in which specialization on specific ant partners is uncommon. In this paper, we demonstrate species-specific seed dispersal of spotted spurge (Chamaesyce maculata) by ants in Japan. C. maculata produces seeds from summer to autumn in Japan. The seeds produced in autumn are carried by two ant species, Tetramorium tsu...

  5. One-dimensional Analytical Modelling of Floating Seed Dispersal in Tidal Channels

    Science.gov (United States)

    Shi, W.; Purnama, A.; Shao, D.; Cui, B.; Gao, W.

    2017-12-01

    Seed dispersal is a primary factor influencing plant community development, and thus plays a critical role in maintaining wetland ecosystem functioning. However, compared with fluvial seed dispersal of riparian plants, dispersal of saltmarsh plant seeds in tidal channels is much less studied due to its complex behavior, and relevant mathematical modelling is particularly lacking. In this study, we developed a one-dimensional advection-dispersion model to explore the patterns of tidal seed dispersal. Oscillatory tidal current and water depth were assumed to represent the tidal effects. An exponential decay coefficient λ was introduced to account for seed deposition and retention. Analytical solution in integral form was derived using Green's function and further evaluated using numerical integration. The developed model was applied to simulate Spartina densiflora seed dispersal in a tidal channel located at the Mad River Slough in North Humboldt Bay, California, USA, to demonstrate its practical applicability. Model predictions agree satisfactorily with field observation and simulation results from Delft3D numerical model. Sensitivity analyses were also conducted to evaluate the effects of varying calibrated parameters on model predictions. The range of the seed dispersion as well as the distribution of the seed concentration were further analyzed through statistical parameters such as centroid displacement and variance of the seed cloud together with seed concentration contours. Implications of the modelling results on tidal marsh restoration and protection, e.g., revegetation through seed addition, were also discussed through scenario analysis. The developed analytical model provides a useful tool for ecological management of tidal marshes.

  6. Seed dispersal as an ecosystem service: frugivore loss leads to decline of a socially valued plant, Capsicum frutescens.

    Science.gov (United States)

    Egerer, Monika H; Fricke, Evan C; Rogers, Haldre S

    2018-04-01

    Species interactions, both mutualistic and antagonistic, are widely recognized as providing important ecosystem services. Fruit-eating animals influence plant recruitment by increasing germination during gut passage and moving seeds away from conspecifics. However, relative to studies focused on the importance of frugivores for plant population maintenance, few studies target frugivores as ecosystem service providers, and frugivores are underappreciated as ecosystem service providers relative to other mutualists such as pollinators. Here, we use an accidental experiment to elucidate the role of seed dispersal by frugivores for maintaining a culturally and economically important plant, the donne' sali chili (Capsicum frutescens) in the Mariana Islands. One of the islands (Guam) has lost nearly all of its native forest birds due to an invasive snake (Boiga irregularis), whereas nearby islands have relatively intact bird populations. We hypothesized that frugivore loss would influence chili recruitment and abundance, which could have economic and cultural impacts. By using video cameras, we confirmed that birds were the primary seed dispersers. We used captive bird feeding trials to obtain gut-passed seeds to use in a seedling emergence experiment. The experiment showed that gut-passed seeds emerged sooner and at a higher proportion than seeds from whole fruits. Consistent with our findings that birds benefit chilies, we observed lower chili abundance on Guam than on islands with birds. In a survey questionnaire of island residents, the majority of residents reported an association between the wild chili and local cultural values and traditions. In addition, we identified a thriving market for chili products, suggesting benefits of wild chilies to people in the Marianas both as consumers and producers. Our study therefore documents seed dispersal as both a cultural and a supporting ecosystem service. We provide a comprehensive case study on how seed-dispersed plants

  7. Variation in seed dispersal along an elevational gradient in Great Smoky Mountains National Park

    Science.gov (United States)

    Zelikova, Tamara J.; Dunn, Robert R.; Sanders, Nathan J.

    2008-09-01

    Seed dispersal by ants is ecologically important and geographically widespread as 20-50% of all herbaceous species in eastern deciduous forests are dispersed by ants, but we know little about how or why such interactions vary geographically. In this paper, we examined variation in seed dispersal by ants along an extensive elevational gradient (256-2025 m) in the Great Smoky Mountains National Park, USA. Specifically, we asked whether variation in ant community composition affected seed removals and seed dispersal distance of Trillium undulatum and Hexastylis arifolia, two common understory herbs found throughout the southern Appalachian Mountains. We also examined variation in myrmecochore abundance, specifically Trillium spp. and H. arifolia, along the same elevational gradient. Measures of ant community and climate variables strongly covaried with elevation, while Trillium species richness and abundance did not. We found that seed removals decreased with elevation, but seed dispersal distance did not depend on elevation. The most important variables predicting seed removals were average annual temperature and the abundance of Aphaenogaster rudis, both of which varied along the elevational gradient. Seed dispersal by ants did not depend on ant community composition, but was dominated by one species, A. rudis, which occurred at every site and removed the vast majority of all observed seeds in this study. Though the ant fauna in the Great Smoky Mountains National Park is diverse, dispersal of T. undulatum and H. arifolia, and likely other myrmecochores, is driven by one ant species, A. rudis.

  8. Seed Dispersal by Bats Over Successional Gradients in the Colombian Orinoquia (San Martin, Meta, Colombia

    Directory of Open Access Journals (Sweden)

    Diego Casallas-Pabón

    2017-09-01

    Full Text Available Faunal seed dispersal plays a fundamental role in plant reproduction. Bats are one of the most important seed dispersers in Neotropical ecosystems. The objective of this research was to describe the bat community and seeds that are potentially dispersed in a successional gradient (savanna, woods, forest edge and riparian forest in a locality of the Colombian Altillanura. We measured abundance, richness, and diversity of bats and the seeds found in their feces. 534 individuals belonging to four families and 39 species were captured. The most abundant species were Carollia perspicillata, Artibeus obscurus and Molossus molossus. C. perspicillata and A. obscurus presented the highest values in the seed dispersion index (DII. The records belong to six guilds, the most abundant being frugivores (sedentary and nomadic. The habitat with the greatest bat abundance and richness of species was the forest edge. A total of 11808 seeds with Cecropia engleriana were collected as the most abundant species. Successional states differed significantly in seed abundance but not in wealth, and certain genera showed dominance. Shrubs were highlighted for their dynamic succession and a potential flow of diverse seeds. Here bats play a fundamental role in seed dispersal since those flying over open areas have the same seed load for dispersal as those found in forest, exhibiting a regeneration potential that is contributed to by a bat community having a diverse structure in trophic groups and species.

  9. The role of animal seed dispersal in accelerating native forest regeneration on degraded tropical lands.

    Science.gov (United States)

    J.M. Wunderle Jr.

    1997-01-01

    this paper reviews the characteristicas of animal seed dispersal. relevant to tropical forest restoration efforts and discusses their managment implication. In many tropical regions seed dispersal by animals is the predominant form of dissemination of propagules and has a potential to facilitate recolonization of native vegetation on degraded sites.

  10. Extremely long-distance seed dispersal by an overfished Amazonian frugivore.

    Science.gov (United States)

    Anderson, Jill T; Nuttle, Tim; Saldaña Rojas, Joe S; Pendergast, Thomas H; Flecker, Alexander S

    2011-11-22

    Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the large-bodied characid, Colossoma macropomum. During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be crucial for the maintenance of Amazonian wetland forests. Unlike frugivorous mammals and birds, little is known about seed dispersal effectiveness of fishes. Extensive mobility of frugivorous fish could result in extremely effective, multi-directional, long-distance seed dispersal. Over three annual flood seasons, we tracked fine-scale movement patterns and habitat use of wild Colossoma, and seed retention in the digestive tracts of captive individuals. Our mechanistic model predicts that Colossoma disperses seeds extremely long distances to favourable habitats. Modelled mean dispersal distances of 337-552 m and maximum of 5495 m are among the longest ever reported. At least 5 per cent of seeds are predicted to disperse 1700-2110 m, farther than dispersal by almost all other frugivores reported in the literature. Additionally, seed dispersal distances increased with fish size, but overfishing has biased Colossoma populations to smaller individuals. Thus, overexploitation probably disrupts an ancient coevolutionary relationship between Colossoma and Amazonian plants.

  11. Long-distance seed dispersal by straw-coloured fruit bats varies by season and landscape

    Directory of Open Access Journals (Sweden)

    Michael Abedi-Lartey

    2016-07-01

    Full Text Available On-going fragmentation of tropical forest ecosystems and associated depletion of seed dispersers threatens the long-term survival of animal-dispersed plants. These threats do not only affect biodiversity and species abundance, but ultimately ecosystem functions and services. Thus, seed dispersers such as the straw-coloured fruit bat, E. helvum, which traverse long distances across fragmented landscapes, are particularly important for maintaining genetic connectivity and colonizing new sites for plant species. Using high-resolution GPS-tracking of movements, field observations and gut retention experiments, we quantify dispersal distances for small- and large-seeded fruits foraged by E. helvum during periods of colony population low (wet season and high (dry season in an urban and a rural landscape in the forest zone of Ghana. Gut passage time averaged 116 min (range 4–1143 min, comparable to other fruit bats. Movements were generally longer in the urban than in the rural landscape and also longer in the dry than in the wet season. As the majority of seeds are dispersed only to feeding roosts, median dispersal distances were similar for both large (42–67 m and small (42–65 m seeds. However, small seeds were potentially dispersed up to 75.4 km, four times further than the previous maximum distance estimated for a similar-sized frugivore. Maximum seed dispersal distances for small seeds were almost twice as long in the rural (49.7 km compare to the urban (31.2 km landscape. Within the urban landscape, estimated maximum dispersal distances for small seeds were three times longer during the dry season (75.4 km compared to the wet season (22.8 km; in contrast, distances in the rural landscape were three times longer in the wet season (67 km compared to the dry season (24.4. Dispersal distances for large seeds during the dry season (551 m in the rural landscape were almost twice that in the wet season (319 m. We found no influence of food

  12. Estimating adhesive seed-dispersal distances : field experiments and correlated random walks

    NARCIS (Netherlands)

    Mouissie, AM; Lengkeek, W; van Diggelen, R

    1. In this study we aimed to estimate distance distributions of adhesively dispersed seeds and the factors that determine them. 2. Seed attachment and detachment were studied using field experiments with a real sheep, a sheep dummy and a cattle dummy. Seed-retention data were used in correlated

  13. Seed dispersal by mowing machinery in a Dutch brook valley system

    NARCIS (Netherlands)

    Strykstra, RJ; Bakker, JP; Verweij, G.L.

    1997-01-01

    Seed dispersal by mowing machinery was investigated within a grassland reserve. Transported seed numbers amounted to hundreds of thousands. Seeds of 26 species were found on the machinery, including species that play an important role in succession during vegetation restoration (Holcus lanatus,

  14. Consequences of intraspecific seed-size variation in Sparganium emersum for dispersal by fish

    NARCIS (Netherlands)

    Pollux, B.J.A.; Ouborg, J.; Van Groenendael, J.M.; Klaassen, M.R.J.

    2007-01-01

    The potential for seed dispersal by fish (ichthyochory) is likely to vary within aquatic plant species, depending on intraspecific variation in phenotypic seed traits. 2. We studied the effect of seed size variation within the unbranched burreed (Sparganium emersum) on the potential for internal

  15. Intraspecific variation of seed floating ability in Sparganium emersum suggests a bimodal dispersal strategy

    NARCIS (Netherlands)

    Pollux, B.J.A.; Verbruggen, E.; Van Groenendael, J.M.; Ouborg, N.J.

    2009-01-01

    Water-mediated spread of seeds (hydrochory) plays an important role in the dispersal of aquatic plants. In this study we investigate intraspecific variation in floating ability and germination capacity of Sparganium emersum seeds in relation to seed mass, within three natural populations along the

  16. Reconsidering the effects of tannin on seed dispersal by rodents: evidence from enclosure and field experiments with artificial seeds.

    Science.gov (United States)

    Zhang, Mingming; Steele, Michael A; Yi, Xianfeng

    2013-11-01

    The question of how tannin affects feeding and hoarding preferences of rodents still remains poorly understood, in part, because it is difficult to control for other seed traits when considering the sole effect of tannin. Here, we constructed a series of artificial 'seeds' with different tannin levels, made from wheat flour, peanut powder and hydrolysable tannins, to determine the direct effects of tannin on both feeding and hoarding preferences. We first presented 'seeds' to individual rodents of two species (Tamias sibiricus and Apodemus peninsulae) confined in semi-natural enclosures and then monitored patterns of seed dispersal and consumption by free-ranging animals in a temperate forest in the Xiaoxing'an Mountains, Heilongjiang Province of China. Our results showed that small rodents displayed a significant preference for low-tannin 'seeds' for both consumption and caching in both captive and field experiments. Moreover, our two-year study consistently showed that tannin concentration was significantly and negatively correlated with the number of cached 'seeds' at both the individual and population levels. Seed size, compared with tannin concentrations, appeared to have little effect on dispersal distances and the number of 'seeds' cached. Low-tannin 'seeds' tended to be dispersed greater distances by rodents in the field than those with higher levels of tannin. These results failed to support those of previous reports indicating that acorns containing higher tannins are more likely to be cached by food hoarding animals. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction.

    Science.gov (United States)

    Pires, Mathias M; Galetti, Mauro; Donatti, Camila I; Pizo, Marco A; Dirzo, Rodolfo; Guimarães, Paulo R

    2014-08-01

    The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.

  18. Seed Dispersal by Ants in the Semi-arid Caatinga of North-east Brazil

    Science.gov (United States)

    Leal, Inara R.; Wirth, Rainer; Tabarelli, Marcelo

    2007-01-01

    Background and Aims Myrmecochory is a conspicuous feature of several sclerophyll ecosystems around the world but it has received little attention in the semi-arid areas of South America. This study addresses the importance of seed dispersal by ants in a 2500-km2 area of the Caatinga ecosystem (north-east Brazil) and investigates ant-derived benefits to the plant through myrmecochory. Methods Seed manipulation and dispersal by ants was investigated during a 3-year period in the Xingó region. Both plant and ant assemblages involved in seed dispersal were described and ant behaviour was characterized. True myrmecochorous seeds of seven Euphorbiaceae species (i.e. elaiosome-bearing seeds) were used in experiments designed to: (1) quantify the rates of seed cleaning/removal and the influence of both seed size and elaiosome presence on seed removal; (2) identify the fate of seeds dispersed by ants; and (3) document the benefits of seed dispersal by ants in terms of seed germination and seedling growth. Key Results Seed dispersal by ants involved one-quarter of the woody flora inhabiting the Xingó region, but true myrmecochory was restricted to 12·8 % of the woody plant species. Myrmecochorous seeds manipulated by ants faced high levels of seed removal (38–84 %) and 83 % of removed seeds were discarded on ant nests. Moreover, seed removal positively correlated with the presence of elaiosome, and elaiosome removal increased germination success by at least 30 %. Finally, some Euphorbiaceae species presented both increased germination and seedling growth on ant-nest soils. Conclusions Myrmecochory is a relevant seed dispersal mode in the Caatinga ecosystem, and is particularly frequent among Euphorbiaceae trees and shrubs. The fact that seeds reach micro-sites suitable for establishment (ant nests) supports the directed dispersal hypothesis as a possible force favouring myrmecochory in this ecosystem. Ecosystems with a high frequency of myrmecochorous plants appear not

  19. The seed dispersal catapult of Cardamine parviflora (Brassicaceae) is efficient but unreliable.

    Science.gov (United States)

    Hayashi, Marika; Gerry, Shannon P; Ellerby, David J

    2010-10-01

    Seed dispersal performance is an essential component of plant fitness. Despite their significance in shaping performance, the mechanical processes that drive dispersal are poorly understood. We have quantified seed dispersal mechanics in Cardamine parviflora (Brassicaceae), a ballistic disperser that launches seeds with specialized catapult-like structures. To determine which aspects of catapult function dictate interspecific dispersal differences, we compared this disperser with other ballistic dispersers. Comparison with brassicas that lack ballistic dispersal may also provide insight into the evolution of this mechanism. • Catapult performance was quantified using high-speed video analysis of dehiscence, ballistic modeling of seed trajectories, and measuring the mechanical energy storage capacity of the spring-like siliqua valve tissue that launched the seeds. • The siliquae valves coiled rapidly outward, launching the seeds in 4.7 ± 1.3 ms (mean ± SD, N = 11). Coiling was likely driven by the bilayered valve structure. The catapult was 21.3 ± 10.3% efficient (mean ± SD, N = 11) at transferring stored elastic energy to the seeds as kinetic energy. The majority of seeds (71.4%) were not launched effectively. • The efficiency of the C. parviflora catapult was high in comparison to that of a ballistic diplochore, a dispersal mode associated with poor ballistic performance, although the unreliability of the launch mechanism limited dispersal distance. Effective launching requires temporary seed-valve adhesion. The adhesion mechanism may be the source of the unreliability. Valve curvature is likely driven by the bilayered valve structure, a feature absent in nonballistic brassicas.

  20. Refaunation and the reinstatement of the seed-dispersal function in Gorongosa National Park.

    Science.gov (United States)

    Correia, Marta; Timóteo, Sérgio; Rodríguez-Echeverría, Susana; Mazars-Simon, Alban; Heleno, Ruben

    2017-02-01

    Large animals are important seed dispersers; however, they tend to be under a high extinction risk worldwide. There is compelling evidence that the global biodiversity crisis is leading to the deterioration of several ecosystem functions, but there is virtually no information on how large-scale refaunation efforts can reinstate seed dispersal. We evaluated the effectiveness of a 62-km 2 wildlife sanctuary, which was established to recover populations of large mammals in Gorongosa National Park (Mozambique), in restoring seed dispersal. We collected animal scats during the dry season of 2014 (June-August) along 5 transects inside and 5 transects outside the sanctuary fence (50 km total) with the same type of plant community, identified animal and plant species in the transects, and quantified the number of seeds in each scat. Based on these data, we built bipartite networks and calculated network and species-level descriptor values, and we compared data collected inside and outside the sanctuary. There were more scats (268 vs. 207) and more scats containing seeds (132 vs. 94) inside than outside the sanctuary. The number of mammal dispersers was also higher inside (17) than outside the sanctuary (11). Similarly, more seeds (2413 vs. 2124) and plant species (33 vs. 26) were dispersed inside than outside the sanctuary. Overall, the seed-dispersal network was less specialized (0.38 vs. 0.44) and there was a greater overlap (0.16 vs. 0.07) inside than outside the sanctuary. Both networks were significantly modular and antinested. The high number and richness of seeds dispersed inside the sanctuary was explained mostly by a higher abundance of dispersers rather than by disperser identity. Our results suggest conservation efforts aimed at recovering populations of large mammals are helping to reestablish not only target mammal species but also their functional roles as seed dispersers in the ecosystem. © 2016 Society for Conservation Biology.

  1. Negative density dependence of seed dispersal and seedling recruitment in a Neotropical palm

    NARCIS (Netherlands)

    Jansen, Patrick A.; Visser, Marco D.; Wright, S. Joseph; Rutten, Gemma; Muller-Landau, Helene C.

    Negative density dependence (NDD) of recruitment is pervasive in tropical tree species. We tested the hypotheses that seed dispersal is NDD, due to intraspecific competition for dispersers, and that this contributes to NDD of recruitment. We compared dispersal in the palm Attalea butyracea across a

  2. Seed dispersal into wetlands: Techniques and results for a restored tidal freshwater marsh

    Science.gov (United States)

    Neff, K.P.; Baldwin, A.H.

    2005-01-01

    Although seed dispersal is assumed to be a major factor determining plant community development in restored wetlands, little research exists on density and species richness of seed available through dispersal in these systems. We measured composition and seed dispersal rates at a restored tidal freshwater marsh in Washington, DC, USA by collecting seed dispersing through water and wind. Seed dispersal by water was measured using two methods of seed collection: (1) stationary traps composed of coconut fiber mat along an elevation gradient bracketing the tidal range and (2) a floating surface trawl net attached to a boat. To estimate wind dispersal rates, we collected seed from stationary traps composed of coconut fiber mat positioned above marsh vegetation. We also collected a small number of samples of debris deposited along high tide lines (drift lines) and feces of Canada Goose to explore their seed content. We used the seedling emergence method to determine seed density in all samples, which involved placing the fiber mats or sample material on top of potting soil in a greenhouse misting room and enumerating emerging seedlings. Seedlings from a total of 125 plant species emerged during this study (including 82 in river trawls, 89 in stationary water traps, 21 in drift lines, 39 in wind traps, and 10 in goose feces). The most abundant taxa included Bidens frondosa, Boehmeria cylindrica, Cyperus spp., Eclipta prostrata, and Ludwigia palustris. Total seedling density was significantly greater for the stationary water traps (212 + 30.6 seeds/m2/month) than the equal-sized stationary wind traps (18 + 6.0 seeds/m(2)/month). Lower-bound estimates of total species richness based on the non-parametric Chao 2 asymptotic estimators were greater for seeds in water (106 + 1.4 for stationary water traps and 104 + 5.5 for trawl samples) than for wind (54 + 6.4). Our results indicate that water is the primary source of seeds dispersing to the site and that a species-rich pool

  3. Evaluating realized seed dispersal across fragmented tropical landscapes : a two-fold approach using parentage analysis and the neighbourhood model

    NARCIS (Netherlands)

    Ismail, Sascha A.; Ghazoul, Jaboury; Ravikanth, Gudasalamani; Kushalappa, Cheppudira G.; Uma Shaanker, Ramanan; Kettle, Chris J.

    2017-01-01

    Despite the importance of seed dispersal for survival of plant species in fragmented landscapes, data on seed dispersal at landscape scales remain sparse. Effective seed dispersal among fragments determines recolonization and plant species persistence in such landscapes. We present the first

  4. The effect of seed morphology on the potential dispersal of aquatic macrophytes by the common carp (Cyprinus carpio)

    NARCIS (Netherlands)

    Pollux, B.J.A.; de Jong, M.D.E.; Steegh, A.; Ouborg, N.J.; Van Groenendael, J.M.; Klaassen, M.R.J.

    2006-01-01

    1. The potential for seed dispersal by fish (ichthyochory) will vary among aquatic plants because of differences in seed size and morphology. 2. To examine how seed morphology influences the probability of dispersal by the common carp (Cyprinus carpio), we studied seed ingestion, retention time and

  5. No evidence for a Ganoderma spore dispersal mutualism in an obligate spore-feeding beetle Zearagytodes maculifer.

    Science.gov (United States)

    Kadowaki, Kohmei; Leschen, Richard A B; Beggs, Jacqueline R

    2011-08-01

    The role of spore dispersal mutualism remains equivocal in many fungus-insect assemblages. We tested experimentally whether an obligate spore-feeding beetle Zearagytodes maculifer has a mutualistic relationship with its host bracket fungus Ganoderma cf. applanatum via spore dispersal. We asked three specific questions: (1) whether or not Ganoderma spore germination rate is increased via beetle digestive activity and (2) is dependent on temperature and sporocarp identity. Spore germination rates were examined in 2×3×2 factorial experiments (spores consumed by beetles or not×temperature 20, 25, and 30°C×two independent pairs of sporocarp-beetle populations) replicated five times in an array of 60 experimental cultures. Analysis showed that consumption by beetles significantly reduced germination rate of Ganoderma spores. The effect of temperature was modulated by the effect of individual sporocarp, and was overridden by beetle feeding. Microscopic analysis revealed that spores from beetle faecal pellets exhibited extensive damage to their thin outer walls (pellicles) and thick inner walls, as well as significant loss of cytoplasm, while control spores were intact. The overall evidence argued against our spore dispersal mutualism hypothesis, suggesting that Z. maculifer can potentially exert a negative, if vanishingly small, fitness effect on its host fungus G. cf. applanatum. Copyright © 2011 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  6. Mineral Licks Attract Neotropical Seed-Dispersing Bats

    International Nuclear Information System (INIS)

    Voigt, Ch.C.; Dechmann, D.K.N.; Dechmann, D.K.N.; Kunz, Th.H.; Bender, J.; Rinehart, B.J.; Michener, R.H.

    2007-01-01

    Unlike most terrestrial mammals, female bats must supply their offspring with all required nutrients until pups achieve virtually adult size, at which time they are able to fly and become independent. Access to nutrients may be especially challenging for reproductively active females in mineral-poor landscapes such as tropical rain forests. We hypothesized that pregnant and lactating females from tropical landscapes acquire essential nutrients from locally-available mineral licks. We captured ten times as many bats at mineral licks than at control sites in a lowland rain forest in eastern Ecuador. Among bats captured at mineral licks, the sex ratio was heavily biased toward females, and a significantly higher portion of females captured at these sites, compared to control sites, were reproductively active (pregnant and lactating). Enrichment of N 15 in relation to N 14 in wing tissue indicated that bats captured at mineral licks were mostly fruit-eating species. Given the high visitation rates of reproductive active females at mineral licks, it is likely that mineral licks are important for fruit-eating female bats as a mineral source during late pregnancy and lactation. By sustaining high population densities of fruit-eating bats that disperse seeds, mineral licks may have an indirect influence on local plant species richness.

  7. Mineral Licks Attract Neotropical Seed-Dispersing Bats

    Directory of Open Access Journals (Sweden)

    Christian C. Voigt

    2007-01-01

    Full Text Available Unlike most terrestrial mammals, female bats must supply their offspring with all required nutrients until pups achieve virtually adult size, at which time they are able to fly and become independent. Access to nutrients may be especially challenging for reproductively active females in mineral-poor landscapes such as tropical rainforests. We hypothesized that pregnant and lactating females from tropical landscapes acquire essential nutrients from locally-available mineral licks. We captured ten times as many bats at mineral licks than at control sites in a lowland rainforest in eastern Ecuador. Among bats captured at mineral licks, the sex ratio was heavily biased toward females, and a significantly higher portion of females captured at these sites, compared to control sites, were reproductively active (pregnant and lactating. Enrichment of N15 in relation to N14 in wing tissue indicated that bats captured at mineral licks were mostly fruit-eating species. Given the high visitation rates of reproductive active females at mineral licks, it is likely that mineral licks are important for fruit-eating female bats as a mineral source during late pregnancy and lactation. By sustaining high population densities of fruit-eating bats that disperse seeds, mineral licks may have an indirect influence on local plant species richness.

  8. Global patterns in post-dispersal seed removal by invertebrates and vertebrates.

    Science.gov (United States)

    Peco, Begoña; Laffan, Shawn W; Moles, Angela T

    2014-01-01

    It is commonly accepted that species interactions such as granivory are more intense in the tropics. However, this has rarely been tested. A global dataset of post-dispersal seed removal by invertebrates and vertebrates for 79 native plant species from semi-natural and natural terrestrial habitats ranging from 55° N to 45° S, was compiled from the global literature to test the hypothesis that post-dispersal seed removal by invertebrates and vertebrates is more intense at lower latitudes. We also quantified the relationship between post-dispersal seed removal by vertebrates and by invertebrates to global climatic features including temperature, actual evapotranspiration (AET) and rainfall seasonality. Linear mixed effect models were applied to describe the relationships between seed removal and latitude, hemisphere and climatic variables controlling for the effect of seed mass. Post-dispersal seed removal by invertebrates was negatively related to latitude. In contrast, post-dispersal seed removal by vertebrates was positively but weakly related to latitude. Mean annual temperature and actual evapotranspiration were positively related to post-dispersal seed removal by invertebrates, but not to post-dispersal seed removal by vertebrates, which was only marginally negatively related to rainfall seasonality. The inclusion of seed mass improved the fit of all models, but the term for seed mass was not significant in any model. Although a good climatic model for predicting post-dispersal seed predation by vertebrates at the global level was not found, our results suggest different and opposite latitudinal patterns of post-dispersal seed removal by invertebrates vs vertebrates. This is the first time that a negative relationship between post-dispersal seed removal by invertebrates and latitude, and a positive relationship with temperature and AET have been documented at a global-scale. These results have important implications for understanding global patterns in plant

  9. Seeds Recovered from the Droppings at Latrines of the Raccoon Dog (Nyctereutes procyonoides viverrinus): The Possibility of Seed Dispersal.

    Science.gov (United States)

    Sakamoto, Yuka; Takatsuki, Seiki

    2015-04-01

    Medium-sized carnivorous mammals are important seed dispersers of fleshy fruits. The raccoon dog (Nyctereutes procyonoides viverrinus) often feeds on fleshy fruits and forms latrines. This behavior may potentially lead to seed dispersal. To determine if this is the case, we studied 1) seed recovery in the droppings of raccoon dogs, and 2) the transportation of seeds between habitats using plastic markers in a western suburb of Tokyo, Japan. In total, 32,473 seeds of 50 plant taxa were recovered from 120 raccoon dog droppings during a year, and 95.7% of the seeds were found to be those of fleshy fruits. The species most frequently recovered were the eurya (Eurya japonica, 52.6%), the brambles (Rubus spp., 17.4%), and the black night shade (Solanum nigrum, 16.0%). A total of 7,412 plastic markers were embedded in baits at 14 bait plots and were recovered in the feces of the raccoon dogs at 22 latrines. The "transportation rates" were calculated in 50-m distance classes and found that most seeds (43.5%) were deposited within 50 m from the bait point, suggesting very short seed dispersal distances. Inter-habitat transportation was observed: 64.9% of the retrieved markers deposited in the forest were transported to other places within the forest. In contrast, almost all of the markers (99.4%) deposited in the open site were transported within the same habitat. These findings suggest that the seeds of forest plants bearing berries can be dispersed out of the forest to open areas by raccoon dogs.

  10. Post-dispersal predation and scatterhoarding of Dipteryx panamensis (Papilionaceae) seeds by rodents in Panama.

    Science.gov (United States)

    Forget, Pierre-Michel

    1993-05-01

    In tropical rain forests of Central America, the canopy tree Dipteryx panamensis (Papilionaceae) fruits when overall fruit biomass is low for mammals. Flying and arboreal consumers feed on D. panamensis and drop seeds under the parent or disperse them farther away. Seeds on the ground attract many vertebrate seed-eaters, some of them potential secondary seed dispersers. The fate of seeds artificially distributed to simulate bat dispersal was studied in relation to fruitfall periodicity and the visiting frequency of diurnal rodents at Barro Colorado Island (BCI), Panama. The frequency of visits by agoutis is very high at the beginning of fruitfall, but in the area close (50 m) away (Dipteryx-poor and Gustavia-rich area). Squirrels were usually observed in the Dipteryx-rich area. Along with intense post-dispersal seed predation by rodents in the Dipteryx-rich area, a significant proportion of seeds were cached by rodents in the Dipteryx-poor area. Post-dispersal seed predation rate was inversely related to hoarding rate. A significantly greater proportion of seeds was cached in March, especially more than 100 m from the nearest fruiting tree. This correlates with the mid-fruiting period, i.e. during the height of D. panamensis fruiting, when rodents seem to be temporarily satiated with the food supply at parent trees. Hoarding remained high toward April, i.e. late in the fruiting season of D. panamensis. Low survival of scatterhoarded seeds suggests that the alternative food supply over the animal's home-ranges in May-June 1990 was too low to promote survival of cached seeds. Seedlings are assumed to establish in the less-used area of the rodents' home-range when overall food supply is sufficient to satiate post-dispersal predators.

  11. Do ungulates facilitate native and exotic plant spread? Seed dispersal by cattle, elk and deer in northeastern Oregon

    Science.gov (United States)

    Anne M. Bartuszevige; Bryan A. Endress

    2008-01-01

    Large domestic and native ungulates have the potential to disperse large quantities of seeds throughout the landscape. Many studies have found that ungulates are capable of dispersing seeds but few quantify the relative importance of ungulate dispersal across the landscape. We investigated the potential for cattle, elk, and deer to disperse native and exotic plants in...

  12. Modeling fine-scale coral larval dispersal and interisland connectivity to help designate mutually-supporting coral reef marine protected areas: Insights from Maui Nui, Hawaii

    Science.gov (United States)

    Storlazzi, Curt; van Ormondt, Maarten; Chen, Yi-Leng; Elias, Edwin P. L.

    2017-01-01

    Connectivity among individual marine protected areas (MPAs) is one of the most important considerations in the design of integrated MPA networks. To provide such information for managers in Hawaii, USA, a numerical circulation model was developed to determine the role of ocean currents in transporting coral larvae from natal reefs throughout the high volcanic islands of the Maui Nui island complex in the southeastern Hawaiian Archipelago. Spatially- and temporally-varying wind, wave, and circulation model outputs were used to drive a km-scale, 3-dimensional, physics-based circulation model for Maui Nui. The model was calibrated and validated using satellite-tracked ocean surface current drifters deployed during coral-spawning conditions, then used to simulate the movement of the larvae of the dominant reef-building coral, Porites compressa, from 17 reefs during eight spawning events in 2010–2013. These simulations make it possible to investigate not only the general dispersal patterns from individual coral reefs, but also how anomalous conditions during individual spawning events can result in large deviations from those general patterns. These data also help identify those reefs that are dominated by self-seeding and those where self-seeding is limited to determine their relative susceptibility to stressors and potential roadblocks to recovery. Overall, the numerical model results indicate that many of the coral reefs in Maui Nui seed reefs on adjacent islands, demonstrating the interconnected nature of the coral reefs in Maui Nui and providing a key component of the scientific underpinning essential for the design of a mutually supportive network of MPAs to enhance conservation of coral reefs.

  13. Modeling Fine-Scale Coral Larval Dispersal and Interisland Connectivity to Help Designate Mutually-Supporting Coral Reef Marine Protected Areas: Insights from Maui Nui, Hawaii

    Directory of Open Access Journals (Sweden)

    Curt D. Storlazzi

    2017-12-01

    Full Text Available Connectivity among individual marine protected areas (MPAs is one of the most important considerations in the design of integrated MPA networks. To provide such information for managers in Hawaii, USA, a numerical circulation model was developed to determine the role of ocean currents in transporting coral larvae from natal reefs throughout the high volcanic islands of the Maui Nui island complex in the southeastern Hawaiian Archipelago. Spatially- and temporally-varying wind, wave, and circulation model outputs were used to drive a km-scale, 3-dimensional, physics-based circulation model for Maui Nui. The model was calibrated and validated using satellite-tracked ocean surface current drifters deployed during coral-spawning conditions, then used to simulate the movement of the larvae of the dominant reef-building coral, Porites compressa, from 17 reefs during eight spawning events in 2010–2013. These simulations make it possible to investigate not only the general dispersal patterns from individual coral reefs, but also how anomalous conditions during individual spawning events can result in large deviations from those general patterns. These data also help identify those reefs that are dominated by self-seeding and those where self-seeding is limited to determine their relative susceptibility to stressors and potential roadblocks to recovery. Overall, the numerical model results indicate that many of the coral reefs in Maui Nui seed reefs on adjacent islands, demonstrating the interconnected nature of the coral reefs in Maui Nui and providing a key component of the scientific underpinning essential for the design of a mutually supportive network of MPAs to enhance conservation of coral reefs.

  14. A genetic evaluation of seed dispersal in the neotropical tree Jacaranda copaia (Bignoniaceae).

    Science.gov (United States)

    Jones, F A; Chen, J; Weng, G-J; Hubbell, S P

    2005-11-01

    Seed dispersal is a critical but poorly understood life-history stage of plants. Here we use a genetic approach to describe seed dispersal patterns accurately in a natural population of the Neotropical tree species Jacaranda copaia (Bignoniaceae). We used microsatellite genotypes from maternally derived tissue on the diaspore to identify which individual of all possible adult trees in the population was the true source of a given seed collected after it dispersed. Wind-dispersed seeds were captured in two different years in a large array of seed traps in an 84-ha mapped area of tropical forest on Barro Colorado Island, Panama. We were particularly interested in the proportion of seeds that traveled long distances and whether there was evidence for direct dispersal into gaps, which are required for successful recruitment of this pioneer tree species. Maximum likelihood procedures were used to fit single- and multiple-component dispersal kernels to the distance data. Mixture models, with separate distributions near and far, best fit the observed dispersal distances, albeit with considerable uncertainty in the tail. We discuss the results in light of different mechanisms responsible for separate distributions near the adult source and in the tail of the curve.

  15. A Switch in Keystone Seed-Dispersing Ant Genera between Two Elevations for a Myrmecochorous Plant, Acacia terminalis.

    Science.gov (United States)

    Thomson, Fiona J; Auld, Tony D; Ramp, Daniel; Kingsford, Richard T

    2016-01-01

    The dispersal capacity of plant species that rely on animals to disperse their seeds (biotic dispersal) can alter with changes to the populations of their keystone dispersal vectors. Knowledge on how biotic dispersal systems vary across landscapes allows better understanding of factors driving plant persistence. Myrmecochory, seed dispersal by ants, is a common method of biotic dispersal for many plant species throughout the world. We tested if the seed dispersal system of Acacia terminalis (Fabaceae), a known myrmecochore, differed between two elevations in the Greater Blue Mountains World Heritage Area, in southeastern Australia. We compared ant assemblages, seed removal rates of ants and other vertebrates (bird and mammal) and the dominant seed-dispersing ant genera. At low elevations (c. 200 m a.s.l) seed removal was predominantly by ants, however, at high elevation sites (c. 700 m a.s.l) vertebrate seed dispersers or seed predators were present, removing over 60% of seeds from experimental depots when ants were excluded. We found a switch in the keystone seed-dispersing ant genera from Rhytidoponera at low elevations sites to Aphaenogaster at high elevation sites. This resulted in more seeds being removed faster at low elevation sites compared to high elevation sites, however long-term seed removal rates were equal between elevations. Differences in the keystone seed removalist, and the addition of an alternate dispersal vector or seed predator at high elevations, will result in different dispersal and establishment patterns for A. terminalis at different elevations. These differences in dispersal concur with other global studies that report myrmecochorous dispersal systems alter with elevation.

  16. A Switch in Keystone Seed-Dispersing Ant Genera between Two Elevations for a Myrmecochorous Plant, Acacia terminalis.

    Directory of Open Access Journals (Sweden)

    Fiona J Thomson

    Full Text Available The dispersal capacity of plant species that rely on animals to disperse their seeds (biotic dispersal can alter with changes to the populations of their keystone dispersal vectors. Knowledge on how biotic dispersal systems vary across landscapes allows better understanding of factors driving plant persistence. Myrmecochory, seed dispersal by ants, is a common method of biotic dispersal for many plant species throughout the world. We tested if the seed dispersal system of Acacia terminalis (Fabaceae, a known myrmecochore, differed between two elevations in the Greater Blue Mountains World Heritage Area, in southeastern Australia. We compared ant assemblages, seed removal rates of ants and other vertebrates (bird and mammal and the dominant seed-dispersing ant genera. At low elevations (c. 200 m a.s.l seed removal was predominantly by ants, however, at high elevation sites (c. 700 m a.s.l vertebrate seed dispersers or seed predators were present, removing over 60% of seeds from experimental depots when ants were excluded. We found a switch in the keystone seed-dispersing ant genera from Rhytidoponera at low elevations sites to Aphaenogaster at high elevation sites. This resulted in more seeds being removed faster at low elevation sites compared to high elevation sites, however long-term seed removal rates were equal between elevations. Differences in the keystone seed removalist, and the addition of an alternate dispersal vector or seed predator at high elevations, will result in different dispersal and establishment patterns for A. terminalis at different elevations. These differences in dispersal concur with other global studies that report myrmecochorous dispersal systems alter with elevation.

  17. Pollination and seed dispersal are the most threatened processes of plant regeneration

    Science.gov (United States)

    Neuschulz, Eike Lena; Mueller, Thomas; Schleuning, Matthias; Böhning-Gaese, Katrin

    2016-07-01

    Plant regeneration is essential for maintaining forest biodiversity and ecosystem functioning, which are globally threatened by human disturbance. Here we present the first integrative meta-analysis on how forest disturbance affects multiple ecological processes of plant regeneration including pollination, seed dispersal, seed predation, recruitment and herbivory. We analysed 408 pairwise comparisons of these processes between near-natural and disturbed forests. Human impacts overall reduced plant regeneration. Importantly, only processes early in the regeneration cycle that often depend on plant-animal interactions, i.e. pollination and seed dispersal, were negatively affected. Later processes, i.e. seed predation, recruitment and herbivory, showed overall no significant response to human disturbance. Conserving pollination and seed dispersal, including the animals that provide these services to plants, should become a priority in forest conservation efforts globally.

  18. Trade-offs between seed dispersal and dormancy in an amphi-basicarpic cold desert annual.

    Science.gov (United States)

    Lu, Juan J; Tan, Dun Y; Baskin, Jerry M; Baskin, Carol C

    2013-12-01

    Several studies have demonstrated trade-offs between depth of seed dormancy and dispersal ability for diaspore-dimorphic species. However, relatively little is known about trade-offs between these two life history traits for a species that produces more than two diaspore morphs. The aim of this study was to investigate the relationship between seed dormancy and dispersal in Ceratocarpus arenarius, an amphi-basicarpic cold desert annual that produces a continuum of dispersal unit morphs. A comparison was made of dispersal and dormancy breaking/germination responses of dispersal units from ground level (a), the middle of the plant canopy (c) and the top of the plant canopy (f). Various features of the morphology and mass of dispersal units and fruits (utricles) were measured. The role of bracteoles in diaspore dispersal by wind, settlement onto the soil surface and dormancy/germination was determined by comparing responses of intact dispersal units and fruits. Movement of dispersal units by wind and animals, seed after-ripening, germination phenology and the presence of water-soluble germination inhibitors in bracteoles were tested using standard procedures. Dispersal units a, c and f differed in morphology and mass; in the majority of cases, extremes were exhibited by a and f, with c being intermediate. Overall, relative dispersal ability was f > c > a, whereas relative intensity of dormancy was a > c > f. Bracteoles increased dispersal distance by wind, enhanced settlement of diaspores onto the soil surface and mechanically inhibited germination. The results provide evidence for a model in which there is a continuous inverse-linear relationship between diaspore dispersal ability and depth of dormancy. Thus, dispersal unit heteromorphism of C. arenarius results in a continuum, from no dispersal ability/high dormancy (dispersal unit a) to high dispersal ability/low dormancy (unit f), which may be a bet-hedging strategy in the cold desert environment.

  19. Analysis of plant soil seed banks and seed dispersal vectors: Its potential and limits for forensic investigations.

    Science.gov (United States)

    Šumberová, Kateřina; Ducháček, Michal

    2017-01-01

    Plant seeds exhibit many species-specific traits, thus potentially being especially helpful for forensic investigations. Seeds of a broad range of plant species occur in soil seed banks of various habitats and may become attached in large quantities to moving objects. Although plant seeds are now routinely used as trace evidence in forensic practice, only scant information has been published on this topic in the scientific literature. Thus, the standard methods remain unknown to specialists in such botanical subjects as plant ecology and plant geography. These specialists, if made aware of the forensic uses of seeds, could help in development of new, more sophisticated approaches. We aim to bridge the gap between forensic analysts and botanists. Therefore, we explore the available literature and compare it with our own experiences to reveal both the potential and limits of soil seed bank and seed dispersal analysis in forensic investigations. We demonstrate that habitat-specific and thus relatively rare species are of the greatest forensic value. Overall species composition, in terms of species presence/absence and relative abundance can also provide important information. In particular, the ecological profiles of seeds found on any moving object can help us identify the types of environments through which the object had travelled. We discuss the applicability of this approach to various European environments, with the ability to compare seed samples with georeferenced vegetation databases being particularly promising for forensic investigations. We also explore the forensic limitations of soil seed bank and seed dispersal vector analyses. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Diversity of terrestrial mammal seed dispersers along a lowland Amazon forest regrowth gradient.

    Science.gov (United States)

    Arévalo-Sandi, Alexander; Bobrowiec, Paulo Estefano D; Rodriguez Chuma, Victor Juan Ulises; Norris, Darren

    2018-01-01

    There is increasing interest in the restoration/regeneration of degraded tropical habitats yet the potential role of natural regenerators remains unclear. We test the hypothesis that the richness and functional diversity of terrestrial mammals differs between forest regrowth stages. We quantified the richness and functional diversity of eight terrestrial mammal seed-disperser species across a forest regrowth gradient in the eastern Brazilian Amazon. We installed camera-traps in 15 sites within small-holder properties with forest regrowth stage classified into three groups, with five sites each of: late second-regrowth forest, early second-regrowth forest and abandoned pasture. Species richness and functional dispersion from the regrowth sites were compared with 15 paired forest control sites. Multi model selection showed that regrowth class was more important for explaining patterns in richness and functional diversity than other variables from three non-mutually exclusive hypotheses: hunting (distance to house, distance to river, distance to town, small holder residence), land cover (% forest cover within 50 meters, 1 kilometer and 5 kilometers) and land use (regrowth class, time since last use). Differences in functional diversity were most strongly explained by a loss of body mass. We found that diversity in regrowth sites could be similar to control sites even in some early-second regrowth areas. This finding suggests that when surrounded by large intact forest areas the richness and functional diversity close to human small-holdings can return to pre-degradation values. Yet we also found a significant reduction in richness and functional diversity in more intensely degraded pasture sites. This reduction in richness and functional diversity may limit the potential for regeneration and increase costs for ecological regeneration and restoration actions around more intense regrowth areas.

  1. A role for fruit structure in seed survival and germination of Swartzia langsdorffii Raddi beyond dispersal.

    Science.gov (United States)

    Vaz, T A A; Rodrigues-Junior, A G; Davide, A C; Nakamura, A T; Toorop, P E

    2018-03-01

    Diaspore structure has been hypothesised to play a role in seed viability and/or germination of recalcitrant seeds, especially for Swartzia langsdorffii. Thus, this work aims to (i) investigate the in situ contribution of pericarp and aril on seed viability and germination, and (ii) identify morphoanatomical traits of S. langsdorffii diaspores that allow its desiccation-sensitive seeds to remain viable. The role of the pericarp and aril in seed survival and germination was investigated by placing the whole fruit, whole seeds (arillate seed) and bare seeds (without aril) in soil in the forest understorey, assessing germination, emergence, dead, firm and predated seeds, and water content of pericarps, arils and seeds. Correlation analysis was performed between environmental variables and physiological parameters. Histochemical features of diaspores were also investigated. Pericarp water content fell after several months, while the aril maintained its water content. Seeds did not lose water even without the presence of the pericarp and aril. However, presence of the pericarp promoted seed water content, viability and germination long after dispersal. The embryo had a thickened outer periclinal cell wall. Pericarp and aril are not essential to prevent water loss in seeds, but do help to retain seed moisture, favouring viability maintenance and promoting germination during the rainy season. Morphoanatomical features of seeds are suggested as main factors that reduce water loss. Survival of these desiccation-sensitive seeds upon dispersal during the dry season appears to be facilitated by multiple diaspore features that prevent viability loss. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  2. Frugivory and seed dispersal by vertebrates in tropical and subtropical Asia: An update

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    Richard T. Corlett

    2017-07-01

    Full Text Available Seed dispersal is a key process in plant communities and frugivory is very important in vertebrate communities. This paper updates a review of frugivory and seed dispersal by vertebrates in the Oriental Region (tropical and subtropical Asia published in 1998. The major conclusions remain the same. Small fruits are consumed by a wide range of potential seed dispersal agents, including species that thrive in small forest fragments and degraded landscapes. Larger and larger-seeded fruits are consumed by progressively fewer dispersers, and the largest depend on a few species of mammals and birds which are highly vulnerable to hunting, fragmentation, and habitat loss. Controlling hunting in both forest areas and the agricultural matrix must be a top priority for conservation. A lot more natural history information has been added to the literature since 1998. This reinforces previous evidence for the importance of hornbills, bulbuls, elephants, gibbons, civets, and fruit bats in seed dispersal, and suggests that the roles of green pigeons, macaques, rodents, bears, and deer were previously underestimated. The taxa for which additional natural history observations would be most valuable include fish, pheasants, pigeons, babblers, rodents, and even-toed ungulates. For other animal taxa, future frugivory and seed dispersal studies need to focus more on the fitness consequences for both the plants and the animals.

  3. The role of Lithodoras dorsalis (Siluriformes: Doradidae as seed disperser in Eastern Amazon

    Directory of Open Access Journals (Sweden)

    Thiago A. P. Barbosa

    2017-06-01

    Full Text Available ABSTRACT Ichthyochory is an important process responsible for the high diversity of plant species in tropical flooded forests. Thus, this study aimed to investigate the role of a catfish species, Lithodoras dorsalis, as seed disperser in the flooded forests at the Amazon River mouth, Brazil. Analyzing the stomach contents of 371 individuals of Lithodoras dorsalis, the Germination Potential (GP% and Germination Speed Index (GSI of seeds that were removed intact were investigated. This allowed us to evaluate the germination performance of two important species of plants in Amazonia, Euterpe oleracea (Açaí and Montrichardia linifera (Aninga, after passage through the digestive tract of this catfish species. Given that digestion by L. dorsalis reduced the germination viability of M. linifera and that seeds were often destroyed during consumption, we suggest that L. dorsalis may have a limited role as seed disperser of M. linifera and instead mostly act as seed predator. However, for the species E. oleracea, L. dorsalis was a potential disperser, since the performance of germination of these seeds was improved after digestion. In addition, the number of seeds consumed was directly proportional to the catfish’s body size, reinforcing the role of doradids as potential seed dispersers in tropical forests.

  4. Post-dispersal seed removal by ground-feeding rodents in tropical peatlands, Central Kalimantan, Indonesia

    OpenAIRE

    Grace V. Blackham; Richard T. Corlett

    2015-01-01

    Forested tropical peatlands in Southeast Asia are being rapidly converted to agriculture or degraded into non-forest vegetation. Although large areas have been abandoned, there is little evidence for subsequent forest recovery. As part of a study of forest degradation and recovery, we used seed removal experiments and rodent surveys to investigate the potential role of post-dispersal seed predation in limiting the regeneration of woody plants. Two 14-day seed removal trials were done in defor...

  5. Post-dispersal seed removal by ground-feeding rodents in tropical peatlands, Central Kalimantan, Indonesia.

    Science.gov (United States)

    Blackham, Grace V; Corlett, Richard T

    2015-09-15

    Forested tropical peatlands in Southeast Asia are being rapidly converted to agriculture or degraded into non-forest vegetation. Although large areas have been abandoned, there is little evidence for subsequent forest recovery. As part of a study of forest degradation and recovery, we used seed removal experiments and rodent surveys to investigate the potential role of post-dispersal seed predation in limiting the regeneration of woody plants. Two 14-day seed removal trials were done in deforested and forested peatland habitat in Central Kalimantan, Indonesia. Seeds of Nephelium lappaceum, Syzygium muelleri, Artocarpus heterophyllus (all animal-dispersed) and Combretocarpus rotundatus (wind-dispersed) were tested. Significantly more seeds (82.8%) were removed in forest than non-forest (38.1%) and Combretocarpus had the lowest removal in both habitats. Most handled seeds were eaten in situ and little caching was observed. Six species of rodents were captured in forest and five in non-forest. The most trapped taxa were three Maxomys spp. in forest (85.5% of individuals) and Rattus tiomanicus in non-forest (74.8%). Camera traps confirmed that rodents were responsible for seed removal. Seed predation in deforested areas, which have a much lower seed rain than forest, may contribute to the low density and diversity of regenerating forest.

  6. Competition as a mechanism structuring mutualisms

    Science.gov (United States)

    Robert J. Warren; Itamar Giladi; Mark A. Bradford

    2014-01-01

    Summary 1. Hutchinsonian niche theory posits that organisms have fundamental abiotic resource requirements from which they are limited by competition. Organisms also have fundamental biotic requirements, such as mutualists, for which they also might compete. 2. We test this idea with a widespread ant–plant mutualism. Ant-mediated seed dispersal (myrmecochory) in...

  7. High seed dispersal ability of Pinus canariensis in stands of contrasting density inferred from genotypic data

    Directory of Open Access Journals (Sweden)

    Unai López de Heredia

    2015-04-01

    Full Text Available Aim of the study: Models that combine parentage analysis from molecular data with spatial information of seeds and seedlings provide a framework to describe and identify the factors involved in seed dispersal and recruitment of forest species. In the present study we used a spatially explicit method (the gene shadow model in order to assess primary and effective dispersal in Pinus canariensis. Area of study: Pinus canariensis is endemic to the Canary Islands (Spain. Sampling sites were a high density forest in southern slopes of Tenerife and a low density stand in South Gran Canaria. Materials and methods: We fitted models based on parentage analysis from seeds and seedlings collected in two sites with contrasting stand density, and then compared the resulting dispersal distributions. Main results: The results showed that: 1 P. canariensis has a remarkable dispersal ability compared to other pine species; 2 there is no discordance between primary and effective dispersals, suggesting limited secondary dispersal by animals and lack of Janzen-Connell effect; and 3 low stand densities enhance the extent of seed dispersal, which was higher in the low density stand. Research highlights: The efficient dispersal mechanism of P. canariensis by wind inferred by the gene shadow model is congruent with indirect measures of gene flow, and has utility in reconstructing past demographic events and in predicting future distribution ranges for the species.

  8. Genetic consequences of seed dispersal to sleeping trees by white-bellied spider monkeys

    Science.gov (United States)

    Karubian, Jordan; Ottewell, Kym; Link, Andres; Di Fiore, Anthony

    2015-10-01

    Frugivorous animals frequently generate clumped distributions of seeds away from source trees via 'destination-based' dispersal processes. For example, use of traditional sleeping trees by white-bellied spider monkeys Ateles belzebuth generates high densities of seeds of a preferred food source, the palm Oenocarpus bataua, at these sites. Little is known about the maternal seed source diversity and population genetic metrics of seed pools encountered at these sites. Given the repeated use of sleeping trees over time, and the fluid social organization and wide ranging movements exhibited by spider monkeys, we predicted that O. bataua seed pools beneath sleeping trees would be characterized by relatively high values of maternal seed source diversity and standard metrics of genetic diversity. Contrary to these expectations, we found relatively low average maternal seed source diversity beneath each of 6 sleeping trees we studied (weighted mean α = 3.74), but considerable variation in diversity of maternal seed sources between sleeping trees (range = 1.75-10.1) and high heterogeneity in standard genetic diversity measures between sleeping trees. There was no evidence for overlap in maternal seed sources between sleeping tree sites (δ = 1.0), resulting in significant genetic differentiation (Fst = 0.055-0.319) between these sites. Observed variation between sleeping trees could not be explained by the number of individual spider monkeys whose core home ranges included a given tree, nor by distance to a central mineral lick, a focal point of spider monkey activity. These findings suggest that spider monkey seed dispersal to sleeping trees is spatially restricted, perhaps because the animals visit sleeping trees at the end of the day and therefore only disperse O. bataua fruits that they ingest late in the day. These results add to our growing appreciation of the ways frugivore behavior mechanistically shapes seed dispersal outcomes.

  9. [Frugivory and seed dispersal Oenocarpus bataua palm (Arecaceae) in a forest from the Colombian Andes].

    Science.gov (United States)

    Rojas-Robles, Rosario; Stiles, F Gary; Muñoz-Saba, Yaneth

    2012-12-01

    Seed dispersal is a key process that determines the spatial structure and dynamics of populations of plants, establishes the potential area of recruitment and in this way, the basis for subsequent processes such as predation, germination, competition and growth. The purpose of this research was to identify the guild of frugivores of the Oenocapus bataua palm in fragments of Andean forest, determine the effective dispersers and relate the spatial distribution of palm populations with the dispersion of seeds. To this end, between August 2005-June 2006, observations of the removal of fruits from eight clusters were done, and counting of consumption of fruits beneath 78 palms with mature fruits was undertaken; focal observations of 13 individuals during 90 hours; registration of frugivory with photographic traps during 165 days/nights for a total of 195 photographs and 144 consumption events; experiments with dispersion using 751 perforated fruits/seeds attached to strings and finally, plots to determine spatial distribution all were carried out. In the study area at least five species of mammals ate, dispersed, buried (Sciurus granatensis, Microsciurus mimulus, Dasyprocta punctata y Proechimys sp.), cover (Marmosa robinsoni) and carried the fruits of O. bataua off to caves (Marmosa robinsoni y Proechimys sp.) without damaging the seed. A 21.7% of the fruits were dispersed, 13.2 gnawed or peeled, 5.6% covered, buried and carried to caves. The average distance of removal of seeds and fruits was 3.1m although in a lesser proportion, dispersion events of >50m were recorded. The abundant production of fruits, their size and weight, their intense removal by frugivores, the short dispersion distances, the absence of large size frugivores (reduced by hunting and fragmentation), that might perform long-distance dispersion, and the increase of rodents, especially squirrels, that strongly pressure the fruit resource, generate a spatially restricted seed rain of seeds responsible

  10. Impact of multiple bird partners on the seed dispersal effectiveness of China's relic trees.

    Science.gov (United States)

    Li, Ning; Li, Xin-Hai; An, Shu-Qing; Lu, Chang-Hu

    2016-01-04

    Frugivorous birds generally exhibit an unequal contribution to dispersal effectiveness of plant species as a function of their habitat adaptation and body size. In our study, we compared the effectiveness of multiple bird species that contribute to the dispersal of the endangered relic Chinese yew, Taxus chinensis. Seven bird species dispersed T. chinensis seeds, with Picus canus, Turdus hortulorum, and Urocissa erythrorhyncha being the main dispersers. The quantity part of dispersal effectiveness was strongly influenced by two inherent characteristics of disperser species: body size and habitat adaptation. However, the quality part of dispersal effectiveness was only influenced by disperser type. For instance, small generalist birds and large specialist birds removed more seeds than other type dispersers. Moreover, small birds and specialist birds contributed slightly more to the dispersal quality of T. chinensis than large birds and generalist birds respectively; however, these differences were not significant. Our results suggest that dispersal effectiveness is affected by variety in the body size and habitat adaptation of different dispersers. Therefore, such variation should be incorporated into spatial and temporal management actions of relic plant species in patchy, human-disturbed habitats.

  11. Seed dispersal and germination patternsin a rare Mediterranean island endemic ( Anchusa crispa Viv., Boraginaceae)

    Science.gov (United States)

    Quilichini, Angélique; Debussche, Max

    2000-12-01

    We analyse and discuss patterns of seed dispersal and germination of a rare endemic plant species, Anchusa crispa Viv. (Boraginaceae) from Corsica and Sardinia. This coastal plant inhabits dunes and back-dunes, and currently numbers only a few thousand individuals which generally occur in isolated populations. This study included experiments conducted in the field in Corsica and also under controlled conditions in the laboratory. Short-distance dispersal of A. crispa is performed by ants, both by myrmecochory and dyszoochory. The invasion of an exotic species of ant, Linepithema humile, could locally modify the dispersal system and possibly the population dynamics of A. crispa. Long-distance dispersal may occur by water transport since seeds can germinate after at least 1 week of immersion in seawater and readily float on the surface. Burial of seeds is favourable for germination, percentage germination being maximised at a depth of 1-2 cm below the soil surface. A. crispa has a seed bank of about ten viable seeds per m 2, which may contribute to the survival of this species which exists in small populations with a short life span. Due to its seed dispersal and germination patterns, the conservation of this species will necessitate that human disturbance, which can destabilise the surface of the sand is prevented and that new populations are introduced to favourable sites.

  12. Dispersers shape fruit diversity in Ficus (Moraceae)

    Science.gov (United States)

    Seed dispersal by vertebrates is one of the most common and important plant-animal mutualisms, involving an enormous diversity of fruiting plants and frugivorous vertebrates. Even though plant reproduction largely depends on seed dispersal, evolutionary ecologists have been unable to link co-occurr...

  13. DISPERSAL OF SEEDS AS NEST MATERIAL BY THE CACTUS WREN

    Science.gov (United States)

    Cactus wren (Campylorhynchus brunneicapillus) nests from the southern Chihuahuan Desert contained viable seeds of grasses, forbs, and shrubs. The most common plants used as construction material in these nests were Muhlenbergia porteri, Boerhavia spicata, and the alien grass Era...

  14. Genetic diversity of dispersed seeds is highly variable among leks of the long-wattled umbrellabird

    Science.gov (United States)

    Ottewell, Kym; Browne, Luke; Cabrera, Domingo; Olivo, Jorge; Karubian, Jordan

    2018-01-01

    Frugivorous animals frequently generate clumped distributions of seeds away from source trees, but genetic consequences of this phenomenon remain poorly resolved. Seed dispersal of the palm Oenocarpus bataua by long-wattled umbrellabirds Cephalopterus penduliger generates high seed densities in leks (i.e., multi-male display sites), providing a suitable venue to investigate how dispersal by this frugivore may influence seed source diversity and genetic structure at local and landscape levels. We found moderate levels of maternal seed source diversity in primary seed rain across five leks in northwest Ecuador (unweighted mean alpha diversity α = 9.52, weighted mean αr = 3.52), with considerable variation among leks (αr range: 1.81-24.55). Qualitatively similar findings were obtained for allelic diversity and heterozygosity. Higher densities of O. bataua adults around leks were associated with higher values of αr and heterozygosity (non-significant trends) and allelic diversity (significant correlation). Seed source overlap between different leks was not common but did occur at low frequency, providing evidence for long-distance seed dispersal by umbrellabirds into leks. Our findings are consistent with the idea that seed pool diversity within leks may be shaped by the interaction between density of local trees, which can vary considerably between leks, and umbrellabird foraging ecology, particularly a lack of territorial defense of fruiting trees. Taken as a whole, this work adds to our growing appreciation of the ways resource distribution and associated frugivore foraging behaviors mechanistically shape seed dispersal outcomes and the distribution of plant genotypes across the landscape.

  15. Effects of artificial roosts for frugivorous bats on seed dispersal in a neotropical forest pasture mosaic.

    Science.gov (United States)

    Kelm, Detlev H; Wiesner, Kerstin R; von Helversen, Otto

    2008-06-01

    In the Neotropics ongoing deforestation is producing open and heavily fragmented landscapes dominated by agriculture, mostly plantations and cattle pastures. After some time agriculture often becomes uneconomical and land is abandoned. Subsequent habitat regeneration may be slow because seed inputs are restricted by a lack of incentives--such as suitable roost sites--for seed dispersers to enter deforested areas. Increasing environmental awareness has fostered growing efforts to promote reforestation. Practical and cost-efficient methods for kick-starting forest regeneration are, however, lacking. We investigated whether artificial bat roosts for frugivorous bat species can attract these key seed dispersers to deforested areas, thereby increasing seed rain. We installed artificial bat roosts in a forest-pasture mosaic in the Costa Rican Atlantic lowlands and monitored bat colonization and seed dispersal. Colonization occurred within a few weeks of installation, and 10 species of bats occupied the artificial roosts. Five species of frugivorous or nectarivorous bats colonized artificial roosts permanently in both primary habitat and in deforested areas, in numbers similar to those found in natural roosts. Seed input around artificial roosts increased significantly. Sixty-nine different seed types, mostly of early-successional plant species, were transported by bats to artificial roosts in disturbed habitats. The installation of artificial bat roosts thus successfully attracted frugivorous bats and increased seed inputs into degraded sites. This method is likely to speed up early-vegetation succession, which in turn will attract additional seed dispersers, such as birds, and provide a microhabitat for seeds of mid- and late-successional plants. As well as supporting natural forest regeneration and bat conservation, this cost-efficient method can also increase environmental awareness among landowners.

  16. Paleocene wind-dispersed fruits and seeds from Colombia and their implications for early Neotropical rainforests

    Directory of Open Access Journals (Sweden)

    Herrera Fabiany

    2014-12-01

    Full Text Available Extant Neotropical rainforests are well known for their remarkable diversity of fruit and seed types. Biotic agents disperse most of these disseminules, whereas wind dispersal is less common. Although wind-dispersed fruits and seeds are greatly overshadowed in closed rainforests, many important families in the Neotropics (e.g., Bignoniaceae, Fabaceae, Malvaceae, Orchidaceae, Sapindaceae show numerous morphological adaptations for anemochory (i.e. wings, accessory hairs. Most of these living groups have high to moderate levels of plant diversity in the upper levels of the canopy. Little is known about the fossil record of wind-dispersed fruits and seeds in the Neotropics. Six new species of disseminules with varied adaptations for wind dispersal are documented here. These fossils, representing extinct genera of Ulmaceae, Malvaceae, and some uncertain families, indicate that wind-dispersed fruit and seed syndromes were already common in the Neotropics by the Paleocene, coinciding with the early development of multistratal rainforests. Although the major families known to include most of the wind-dispersed disseminules in extant rainforests are still missing from the Paleogene fossil record of South and Central America, the new fossils imply that anemochory was a relatively important product and/or mechanism of plant evolution and diversification in early Neotropical rainforests.

  17. Mechanistic models of plant seed dispersal by wind in heterogeneous landscapes

    Science.gov (United States)

    Trakhtenbrot, A.; Katul, G. G.; Nathan, R.

    2010-12-01

    Seed dispersal, and especially long-distance dispersal (LDD), is a key process in plant population survival, colonization, and gene flow. Its importance is amplified by the man-induced habitat fragmentation, climate change and invasions of exotic species. Mechanistic seed dispersal models are central to quantitative prediction of dispersal patterns and understanding their underlying mechanisms. For wind dispersal, most current mechanistic models assume homogenous environment. Although both topography and sharp transitions in vegetation stature profoundly affect wind flow, accounting for these effects via simplified models remains a vexing research problem. Such simplified models are needed to inform ecosystem managers about consequences of landscape fragmentation. We modified the Coupled Eulerian-Lagrangian closure (CELC) mechanistic dispersal model to represent scenarios of wind flow over a sharp transition from short to tall vegetation or over forested hilly terrain, and predicted the resulting dispersal distances and direction. We parameterized the wind and vegetation factors using measurements taken on a hill with short height Mediterranean shrubland and pine forest vegetation at Mt. Pithulim, Israel. For the short-to-tall vegetation transition scenario, the main feature of the modeled wind field is an exponential decay of the mean horizontal wind velocity, assuming that the mean momentum equation simplifies to a balance between the advective acceleration and the drag force terms. As a consequence of the incompressibility condition, this exponential decay leads to strong upward mean vertical velocity component. We found that for seed release downwind of the edge, the simulated median (short) and 99-th percentile (long) distances were longer than those for the homogeneous tall vegetation scenario. For seed release upwind of the edge the effect on dispersal distance was more complex and depended on the release height and he seed terminal velocity of the seeds

  18. Accelerated seed dispersal along linear disturbances in the Canadian oil sands region.

    Science.gov (United States)

    Roberts, David; Ciuti, Simone; Barber, Quinn E; Willier, Caitlin; Nielsen, Scott E

    2018-03-19

    Habitat fragmentation is typically seen as inhibiting movement via erosion in connectivity, although some patterns of early-phase disturbance, such as narrow linear disturbances in otherwise undisturbed forests, may actually facilitate the dispersal of certain species. Such features are common in Alberta's oil sands region as legacies from seismic hydrocarbon exploration used to map oil reserves. Many of the ecological implications of these disturbances are unknown. Here, we investigate the effect of these forest dissections by experimentally testing dispersal patterns along seismic lines compared with adjacent forests using two proxy materials for wind-dispersed seeds, Typha latifolia seed and goose down feathers. We found that wind speeds were up to seven times higher and 95 th percentile seed dispersal distances nearly four times farther on seismic lines compared with undisturbed forests and the corresponding effect of these features on seed dispersal distances can be substantial, potentially facilitating future changes in composition and ecological processes in boreal forests. This raises important considerations for native and invasive species, particularly in the context of climate change and the associated importance of seed movement and migration.

  19. Temporal dynamics of seed excretion by wild ungulates: implications for plant dispersal.

    Science.gov (United States)

    Picard, Mélanie; Papaïx, Julien; Gosselin, Frédéric; Picot, Denis; Bideau, Eric; Baltzinger, Christophe

    2015-07-01

    Dispersal is a key process in metapopulation dynamics as it conditions species' spatial responses to gradients of abiotic and biotic conditions and triggers individual and gene flows. In the numerous plants that are dispersed through seed consumption by herbivores (endozoochory), the distance and effectiveness of dispersal is determined by the combined effects of seed retention time in the vector's digestive system, the spatial extent of its movements, and the ability of the seeds to germinate once released. Estimating these three parameters from experimental data is therefore crucial to calibrate mechanistic metacommunity models of plant-herbivore interactions. In this study, we jointly estimated the retention time and germination probability of six herbaceous plants transported by roe deer (Capreolus capreolus), red deer (Cervus elaphus), and wild boar (Sus scrofa) through feeding experiments and a Bayesian dynamic model. Retention time was longer in the nonruminant wild boar (>36 h) than in the two ruminant species (roe deer: 18-36 h, red deer: 3-36 h). In the two ruminants, but not in wild boar, small and round seeds were excreted faster than large ones. Low germination probabilities of the excreted seeds reflected the high cost imposed by endozoochory on plant survival. Trait-mediated variations in retention time and germination probability among animal and plant species may impact plant dispersal distances and interact with biotic and abiotic conditions at the release site to shape the spatial patterns of dispersed plant species.

  20. Cone and seed traits of two Juniperus species influence roles of frugivores and scatter-hoarding rodents as seed dispersal agents

    Science.gov (United States)

    Dimitri, Lindsay A.; Longland, William S.; Vander Wall, Stephen B.

    2017-11-01

    Seed dispersal in Juniperus is generally attributed to frugivores that consume the berry-like female cones. Some juniper cones are fleshy and resinous such as those of western juniper (Juniperus occidentalis), while others are dry and leathery such as those of Utah juniper (J. osteosperma). Rodents have been recorded harvesting Juniperus seeds and cones but are mostly considered seed predators. Our study sought to determine if rodents play a role in dispersal of western and Utah juniper seeds. We documented rodent harvest of cones and seeds of the locally-occurring juniper species and the alternate (non-local) juniper species in removal experiments at a western juniper site in northeastern California and a Utah juniper site in western Nevada. Characteristics of western and Utah juniper cones appeared to influence removal, as cones from the local juniper species were preferred at both sites. Conversely, removal of local and non-local seeds was similar. Piñon mice (Peromyscus truei) were responsible for most removal of cones and seeds at both sites. We used radioactively labeled seeds to follow seed fate and found many of these seeds in scattered caches (western juniper: 415 seeds in 82 caches, 63.0% of seeds found; Utah juniper: 458 seeds in 127 caches, 39.5% of seeds found) most of which were attributed to piñon mice. We found little evidence of frugivores dispersing Utah juniper seeds, thus scatter-hoarding rodents appear to be the main dispersal agents. Western juniper cones were eaten by frugivores, and scatter-hoarding is a complimentary or secondary form of seed dispersal. Our results support the notion that Utah juniper has adapted to xeric environments by conserving water through the loss of fleshy fruits that attract frugivores and instead relies on scatter-hoarding rodents as effective dispersal agents.

  1. Are weeds hitchhiking a ride on your car? A systematic review of seed dispersal on cars.

    Science.gov (United States)

    Ansong, Michael; Pickering, Catherine

    2013-01-01

    When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487) were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars.

  2. Are Weeds Hitchhiking a Ride on Your Car? A Systematic Review of Seed Dispersal on Cars

    Science.gov (United States)

    Ansong, Michael; Pickering, Catherine

    2013-01-01

    When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487) were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars. PMID:24265803

  3. Are weeds hitchhiking a ride on your car? A systematic review of seed dispersal on cars.

    Directory of Open Access Journals (Sweden)

    Michael Ansong

    Full Text Available When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487 were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars.

  4. Reduced germination success of temperate grassland seeds sown in dung: consequences for post-dispersal seed fate.

    Science.gov (United States)

    Milotić, T; Hoffmann, M

    2016-11-01

    Endozoochory is one of the main drivers shaping temperate grassland communities by maintaining plant populations of its constituents and enabling plants to colonize new habitats. Successful endozoochorous dispersal implies that seeds not only get consumed and survive the digestive tract but are also able to develop into viable seedlings in a dung environment. We experimentally assessed the germination probability and timing of 15 annual and perennial temperate European grassland species in cattle and horse dung and in different climatic conditions (greenhouse and outdoor conditions). Interspecific variation in germinability and germination timing are found, while life strategy had only an effect on germination timing. We found adverse effects of both cattle and horse dung on the germination characteristics of all tested grassland species, but the effects of cattle dung were more pronounced. In comparison with the control treatment, fewer seeds emerged in dung and more time was needed to germinate. Also, germination metrics clearly differed between the artificial greenhouse and outdoor conditions, with generally a lower germinability in outdoor conditions. According to our results, a large cost seems to be associated with endozoochorous dispersal in this stage of the life cycle, as seed dispersal effectiveness strongly depends on the quality of the deposition site with a lowered survival and germination probability when seeds are deposited in dung. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  5. Evidence of eelgrass (Zostera marina seed dispersal by northern diamondback terrapin (Malaclemys terrapin terrapin in lower Chesapeake Bay.

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    Diane C Tulipani

    Full Text Available The initial discovery in May 2009 of eelgrass (Zostera marina seeds in fecal samples of wild-caught northern diamondback terrapins (Malaclemys terrapin terrapin was the first field evidence of eelgrass seed ingestion in this species. This finding suggested the potential of terrapins as seed dispersers in eelgrass beds, which we sampled for two additional years (2010 and 2011. Seeds were only found in feces of terrapins captured prior to June 8 in all three years, coinciding with eelgrass seed maturation and release. Numbers of seeds in terrapin feces varied annually and decreased greatly in 2011 after an eelgrass die off in late 2010. The condition of seeds in terrapin feces was viable-mature, germinated, damaged, or immature. Of terrapins captured during time of seed release, 97% were males and juvenile females, both of which had head widths <30 mm. The fraction of individuals with ingested seeds was 33% for males, 35% for small females, and only 6% for large (mature females. Probability of seed ingestion decreased exponentially with increasing terrapin head width; only males and small females (head width <30 mm were likely to be vectors of seed dispersal. The characteristic that diamondback terrapins have well-defined home ranges allowed us to estimate the number of terrapins potentially dispersing eelgrass seeds annually. In seagrass beds of the Goodwin Islands region (lower York River, Virginia, there were 559 to 799 terrapins, which could disperse between 1,341 and 1,677 eelgrass seeds annually. These would represent a small proportion of total seed production within a single seagrass bed. However, based on probable home range distances, terrapins can easily traverse eelgrass meadow boundaries, thereby dispersing seeds beyond the bed of origin. Given the relatively short dispersion distance of eelgrass seeds, the diamondback terrapin may be a major source of inter-bed seed dispersal and genetic diversity.

  6. Bird-mediated seed dispersal: reduced digestive efficiency in active birds modulates dispersal capacity of plant seeds

    NARCIS (Netherlands)

    Kleyheeg, Erik; Van Leeuwen, C.H.A.; Morison, M.A.; Nolet, Bart; Soons, Merel

    2015-01-01

    Plant populations in fragmented ecosystems rely largely on internal dispersal by animals. To unravel the mechanisms underlying this mode of dispersal, an increasing number of experimental feeding studies is carried out. However, while physical activity is known to affect vertebrate digestive

  7. Habitat differences in dung beetle assemblages in an African savanna-forest ecotone: implications for secondary seed dispersal.

    Science.gov (United States)

    Kunz, Britta K; Krell, Frank-Thorsten

    2011-06-01

    The probability and pattern of secondary seed dispersal by dung beetles (Scarabaeinae) depend on their community structure and composition at the site of primary deposition, which, in turn, seem to be strongly determined by vegetation. Consequently, we expected pronounced differences in secondary seed dispersal between forest and savanna in the northern Ivory Coast, West Africa. We found 99 dung beetle species at experimentally exposed dung piles of the olive baboon (Papio anubis (Lesson, 1827)), an important primary seed disperser in West Africa. Seventy-six species belonged to the roller and tunneler guilds, which are relevant for secondary seed dispersal. Most species showed a clear habitat preference. Contrary to the Neotropics, species number and abundance were much higher in the savanna than in the forest. Rollers and tunnelers each accounted for approximately 50% of the individuals in the savanna, but in the forest rollers made up only 4%. Seeds deposited into the savanna by an omnivorous primary disperser generally have a higher overall probability of being more rapidly dispersed secondarily by dung beetles than seeds in the forest. Also, rollers disperse seeds over larger distances. In contrast to other studies, small rollers were active in dispersal of large seeds, which were seemingly mistaken for dung balls. Our results suggest that rollers can remove seeds from any plant dispersed in primate dung in this ecosystem. © 2011 ISZS, Blackwell Publishing and IOZ/CAS.

  8. Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China.

    Science.gov (United States)

    Li, Ning; Yang, Wen; Fang, Shubo; Li, Xinhai; Liu, Zhanchen; Leng, Xin; An, Shuqing

    2017-01-01

    Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling-safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  9. Disentangling the role of seed bank and dispersal in plant metapopulation dynamics using patch occupancy surveys.

    Science.gov (United States)

    Manna, F; Pradel, R; Choquet, R; Fréville, H; Cheptou, P-O

    2017-10-01

    In plants, the presence of a seed bank challenges the application of classical metapopulation models to aboveground presence surveys; ignoring seed bank leads to overestimated extinction and colonization rates. In this article, we explore the possibility to detect seed bank using hidden Markov models in the analysis of aboveground patch occupancy surveys of an annual plant with limited dispersal. Patch occupancy data were generated by simulation under two metapopulation sizes (N = 200 and N = 1,000 patches) and different metapopulation scenarios, each scenario being a combination of the presence/absence of a 1-yr seed bank and the presence/absence of limited dispersal in a circular 1-dimension configuration of patches. In addition, because local conditions often vary among patches in natural metapopulations, we simulated patch occupancy data with heterogeneous germination rate and patch disturbance. Seed bank is not observable from aboveground patch occupancy surveys, hence hidden Markov models were designed to account for uncertainty in patch occupancy. We explored their ability to retrieve the correct scenario. For 10 yr surveys and metapopulation sizes of N = 200 or 1,000 patches, the correct metapopulation scenario was detected at a rate close to 100%, whatever the underlying scenario considered. For smaller, more realistic, survey duration, the length for a reliable detection of the correct scenario depends on the metapopulation size: 3 yr for N = 1,000 and 6 yr for N = 200 are enough. Our method remained powerful to disentangle seed bank from dispersal in the presence of patch heterogeneity affecting either seed germination or patch extinction. Our work shows that seed bank and limited dispersal generate different signatures on aboveground patch occupancy surveys. Therefore, our method provides a powerful tool to infer metapopulation dynamics in a wide range of species with an undetectable life form. © 2017 by the Ecological Society of America.

  10. An automated method for large-scale monitoring of seed dispersal by ants.

    Science.gov (United States)

    Bologna, Audrey; Toffin, Etienne; Detrain, Claire; Campo, Alexandre

    2017-01-10

    Myrmecochory is the process of seed dispersal by ants; however, it is highly challenging to study, mainly because of the small size of both partners and the comparatively large range of dispersal. The mutualistic interaction between ants and seeds involves the former retrieving diaspores, consuming their elaiosome (a nutrient-rich appendage), and the rejection of seeds from the nest. Here, we introduce a semi-automated method based on stitching high resolution images together, allowing the study of myrmecochory in a controlled environment over time. We validate the effectiveness of our method in detecting and discriminating seeds and ants. We show that the number of retrieved diaspores varies highly among colonies, and is independent of both their size and activity level, even though the dynamics of diaspore collection are correlated with the arrival of ants at the food source. We find that all retrieved seeds are rejected from the nest in a clustered pattern, and, surprisingly, they are also frequently redispersed within the arena afterwards, despite lacking elaiosome. This finding suggests that the dispersal pattern might be more complex and dynamic than expected. Our method unveils new insights on the mechanisms of myrmecochory, and could be usefully adapted to study other dispersal phenomena.

  11. Myiarchus flycatchers are the primary seed dispersers of Bursera longipes in a Mexican dry forest.

    Science.gov (United States)

    Almazán-Núñez, R Carlos; Eguiarte, Luis E; Arizmendi, María Del Coro; Corcuera, Pablo

    2016-01-01

    We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF) in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature) characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha), serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution.

  12. Galápagos land iguana (Conolophus subcristatus) as a seed disperser.

    Science.gov (United States)

    Traveset, Anna; Nogales, Manuel; Vargas, Pablo; Rumeu, Beatriz; Olesen, Jens M; Jaramillo, Patricia; Heleno, Ruben

    2016-05-01

    The role of the most common land iguana (Conolophus subcristatus) in the Galápagos Islands as an effective seed disperser is explored in this study. A total of 5705 seeds of 32 plant species were identified from 160 scats, 4545 of which (80%) appeared visually undamaged. Germination trials of 849 seeds from 29 species revealed that at least 10 species remained viable after passing through the iguana's gut, although only a small proportion of those seeds (4%) germinated. In any case, we argue that C. subcristatus exerts an important role on the 7 Galapagos islands where it occurs because of its abundance and capacity to ingest and disperse seeds at long distances. Our results strongly suggest that the Galápagos C. subcristatus plays an important role as a seed disperser of not only of native species but also some introduced plants in the Galápagos Islands. © 2016 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  13. Myiarchus flycatchers are the primary seed dispersers of Bursera longipes in a Mexican dry forest

    Directory of Open Access Journals (Sweden)

    R. Carlos Almazán-Núñez

    2016-06-01

    Full Text Available We evaluated the seed dispersal of Bursera longipes by birds along a successional gradient of tropical dry forest (TDF in southwestern Mexico. B. longipes is an endemic tree to the TDF in the Balsas basin. The relative abundance of frugivorous birds, their frequency of visits to B. longipes and the number of removed fruits were recorded at three study sites with different stages of forest succession (early, intermediate and mature characterized by distinct floristic and structural elements. Flycatchers of the Myiarchus and Tyrannus genera removed the majority of fruits at each site. Overall, visits to B. longipes were less frequent at the early successional site. Birds that function as legitimate dispersers by consuming whole seeds and regurgitating or defecating intact seeds in the process also remove the pseudoaril from seeds, thereby facilitating the germination process. The highest germination percentages were recorded for seeds that passed through the digestive system of two migratory flycatchers: M. cinerascens and M. nutingii. Perch plants, mainly composed of legumes (e.g., Eysenhardtia polystachya, Acacia cochliacantha, Calliandra eryophylla, Mimosa polyantha, serve also as nurse plants since the number of young individuals recruited from B. longipes was higher under these than expected by chance. This study shows that Myiarchus flycatchers are the most efficient seed dispersers of B. longipes across all successional stages. This suggests a close mutualistic relationship derived from adaptive processes and local specializations throughout the distribution of both taxa, as supported by the geographic mosaic theory of coevolution.

  14. Megagardeners of the forest - the role of elephants in seed dispersal

    Science.gov (United States)

    Campos-Arceiz, Ahimsa; Blake, Steve

    2011-11-01

    As the largest frugivores on Earth, elephants have unique ecological properties. Found in deserts, savannahs, and forests, they are the last remnants of a diverse lineage. Among the three currently recognized forms, African forest elephants are the most frugivorous, followed by Asian and African savannah elephants, although their role as seed dispersers is variable and context-dependent. African forest elephants may consume more seeds from more species than any other taxon of large vertebrate dispersers, defecating them over long distances in viable conditions into nutrient-rich and protective dung. In short, elephants are forest gardeners. The signature of elephant dispersal is evident in the spatial distribution of trees suggesting that elephants maintain tree diversity and retain low redundancy in seed dispersal systems. Large numbers of forest elephants ranging over large areas may be essential for ecosystem function. The loss of elephants will have important negative consequences for the ecological trajectories of some plant species and whole ecological communities, yet the conservation status of forest elephants is catastrophic in Asia and rapidly becoming so in Africa due to hunting and other conflicts with people. In this paper we review the current knowledge of elephants as seed dispersers, discuss the ecological consequences of their decline, and suggest priority areas for research and conservation action.

  15. Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

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    Pedro G. Blendinger

    2017-06-01

    Full Text Available Most fleshy-fruited plants establish strong local interactions with a few fruit-eating species across their distribution range, which can differ among sites and have a major impact for the plant population dynamics. In turn, human disturbances alter both the original animal assemblage with which plants interact and the outcome of the mutualistic interaction. Negative consequences of human disturbances can be weakened when different seed dispersers exert similar effects on plant populations, being functionally equivalent. To understand the consequences of variability in seed dispersers on the recruitment of a long-lived tree species, I assessed changes in the assemblages of avian dispersers of Podocarpus parlatorei in subtropical Andean cloud-forests, and how these changes affect the outcome of the interaction at different spatial scales. The seed dispersal effectiveness (SDE concept, defined as the likelihood of a seed removed by a fruit-eating bird to be dispersed to a suitable site for seed survival and germination, provides the framework to compare the contributions of different birds to seed dispersal. I compared the SDE in two old-growth forests dominated by P. parlatorei and a human disturbed forest, and in the main habitat types of these sites. In all sites, highest SDE values were provided by “gulpers” that swallow the whole fleshy cone (“fruit”, predominantly Elaenia and Turdus species. SDE was highest in forest edges and secondary forests, and negligible in other habitats. Equivalence in SDE was relatively low both within and between forest sites. Human forest disturbance modified the functional equivalence, the generalization in mutualistic interactions and the strength of SDE. Secondary forests showed the higher SDE and the greater richness of dispersers high in SDE; as a consequence, the ecological equivalence increased in the most suitable habitat for recruitment. This could lead to greater resilience of plant populations

  16. Steep Decline and Cessation in Seed Dispersal by Myrmica rubra Ants.

    Science.gov (United States)

    Bologna, Audrey; Detrain, Claire

    2015-01-01

    Myrmecochorous diaspores bear a nutrient-rich appendage, the elaiosome, attractive to ant workers that retrieve them into the nest, detach the elaiosome and reject the seed intact. While this interaction is beneficial for the plant partner by ensuring its seed dispersal, elaiosome consumption has various effects -positive, negative or none - on ants' demography and survival, depending on both the ant/plant species involved. In this context, the contribution of ants to seed dispersal strongly varies according to the ant/plant pairs considered. In this paper, we investigate whether the dynamics of myrmecochory also vary on a temporal scale, for a given pair of partners: Myrmica rubra ants and Viola odorata seeds. During their first encounter with seeds, ants collect all the diaspores and eat the majority of elaiosomes. Both the harvesting effort and the elaiosome consumption decline when seeds are offered on the next week and completely cease for the following weeks. This is related to a decrease in the number of foragers reaching the food source, as well as to a reduced probability for an ant contacting a seed to retrieve it. Seed retrieval is not reactivated after seven weeks without any encounter with V. odorata seeds. By contrast, naive ant colonies only fed with fruit flies do not show a decline of prey harvesting of which the speed of retrieval even increases over the successive weeks. Myrmecochory may thus be labile at the scale of a fruiting season due to the ability of ants to steeply tune and cease for several months the harvesting of these seemingly poorly rewarding items and to maintain cessation of seed exploitation. The present study emphasizes the importance of a long-lasting follow up of the myrmecochory process, to assess the stability of this ant-plant partnership and to identify mechanisms of adaptive harvesting in ants.

  17. Steep Decline and Cessation in Seed Dispersal by Myrmica rubra Ants.

    Directory of Open Access Journals (Sweden)

    Audrey Bologna

    Full Text Available Myrmecochorous diaspores bear a nutrient-rich appendage, the elaiosome, attractive to ant workers that retrieve them into the nest, detach the elaiosome and reject the seed intact. While this interaction is beneficial for the plant partner by ensuring its seed dispersal, elaiosome consumption has various effects -positive, negative or none - on ants' demography and survival, depending on both the ant/plant species involved. In this context, the contribution of ants to seed dispersal strongly varies according to the ant/plant pairs considered. In this paper, we investigate whether the dynamics of myrmecochory also vary on a temporal scale, for a given pair of partners: Myrmica rubra ants and Viola odorata seeds. During their first encounter with seeds, ants collect all the diaspores and eat the majority of elaiosomes. Both the harvesting effort and the elaiosome consumption decline when seeds are offered on the next week and completely cease for the following weeks. This is related to a decrease in the number of foragers reaching the food source, as well as to a reduced probability for an ant contacting a seed to retrieve it. Seed retrieval is not reactivated after seven weeks without any encounter with V. odorata seeds. By contrast, naive ant colonies only fed with fruit flies do not show a decline of prey harvesting of which the speed of retrieval even increases over the successive weeks. Myrmecochory may thus be labile at the scale of a fruiting season due to the ability of ants to steeply tune and cease for several months the harvesting of these seemingly poorly rewarding items and to maintain cessation of seed exploitation. The present study emphasizes the importance of a long-lasting follow up of the myrmecochory process, to assess the stability of this ant-plant partnership and to identify mechanisms of adaptive harvesting in ants.

  18. Dropping rates of elaiosome-bearing seeds during transport by ants ( Formica polyctena Foerst.): Implications for distance dispersal

    Science.gov (United States)

    Gorb, Stanislav N.; Gorb, Elena V.

    1999-09-01

    In a deciduous forest, foraging ants collect elaiosome-bearing seeds and carry them to their nests. Some of the seeds reach the nest and are concentrated there. Others may be dropped by ants during transport. The dropped seeds enter the soil seed pool. However, they might be repeatedly removed by other ant individuals and carried again in the direction of the nest. Rates of seed dropping and repeated removals must be known to evaluate the effect of ant workers on dispersal distance of seeds. The rate of seed dropping is predicted to depend on size of seeds and of elaiosomes, both of which vary among plant species, and on the size of the ant workers. Mark-recapture experiments were used to evaluate dropping rates of seeds of five myrmecochorous and diplochorous plants ( Chelidonium majus L., Asarum europaeum L., Viola matutina Klok., V. mirabilis L., V. hirta L.) during their transport by the ant Formica polyctena Foerst. In the series of species A. europaeum - V. hirta - V. mirabilis - Ch. majus - V. matutina, the dropping rate increased. Small workers dropped seeds of A. europaeum more often than did large ones, while seeds of V. hirta were dropped by ants of different size classes with the same frequency. Across species, dropping rates of seeds were negatively correlated with the rate at which ants removed them from the depot. The number of seeds which reach the nests is the other important parameter of seed dispersal. This parameter depends on dropping rates: seeds with lower dropping rates have higher chances of being deposited in nests. Diplochores usually produce many small seeds, which are characterised by low removal rates and high dropping rates during transport by ants. Obligate myrmecochores produce rather few large seeds, which have high removal rates and low dropping rates. To analyse the significance of seed dropping in the dispersal distance of seeds, a computer simulation based on two factors [(i) seed number produced by a plant; (ii) dropping rate

  19. Seed dispersal of Diospyros virginiana in the past and the present: Evidence for a generalist evolutionary strategy.

    Science.gov (United States)

    Rebein, Mimi; Davis, Charli N; Abad, Helena; Stone, Taylor; Del Sol, Jillian; Skinner, Natalie; Moran, Matthew D

    2017-06-01

    Several North American trees are hypothesized to have lost their co-evolved seed disperser during the late-Pleistocene extinction and are therefore considered anachronistic. We tested this hypothesis for the American persimmon ( Diospyros virginiana ) by studying the effects of gut passage of proposed seed dispersers on seedling survival and growth, natural fruiting characteristics, and modern animal consumption patterns. We tested gut passage effects on persimmon seeds using three native living species, the raccoon ( Procyon lotor ), Virginia opossum ( Didelphis virginiana ), and coyote ( Canis latrans ), and two Pleistocene analogs; the Asian elephant ( Elephas maximus ) and alpaca ( Vicugna pacos ). Persimmon seeds excreted by raccoons, coyotes, and elephants survived gut transit. Gut passage did not affect sprouting success, but did tend to decrease time to sprout and increase seedling quality. Under field conditions, persimmon fruits were palatable on the parent tree and on the ground for an equal duration, but most fruits were consumed on the ground. Seven vertebrate species fed upon persimmon fruits, with the white-tailed deer ( Odocoileus virginianus )-a species not capable of dispersing persimmon seeds-comprising over 90% of detections. Conversely, potential living seed dispersers were rarely detected. Our results suggest the American persimmon evolved to attract a variety of seed dispersers and thus is not anachronistic. However, human-induced changes in mammal communities could be affecting successful seed dispersal. We argue that changes in the relative abundance of mammals during the Anthropocene may be modifying seed dispersal patterns, leading to potential changes in forest community composition.

  20. Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities

    NARCIS (Netherlands)

    van Leeuwen, Casper H. A.; Sarneel, Judith M.; van Paassen, Jose; Rip, Winnie J.; Bakker, Elisabeth S.

    1. Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and

  1. Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities

    NARCIS (Netherlands)

    Van Leeuwen, C.H.A.; Sarneel, J.M.; van Paassen, José; Rip, W.J.; Bakker, E.S.

    2014-01-01

    Summary 1.Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination,

  2. Morphologic and Aerodynamic Considerations Regarding the Plumed Seeds of Tragopogon pratensis and Their Implications for Seed Dispersal.

    Science.gov (United States)

    Casseau, Vincent; De Croon, Guido; Izzo, Dario; Pandolfi, Camilla

    2015-01-01

    Tragopogon pratensis is a small herbaceous plant that uses wind as the dispersal vector for its seeds. The seeds are attached to parachutes that increase the aerodynamic drag force and increase the total distance travelled. Our hypothesis is that evolution has carefully tuned the air permeability of the seeds to operate in the most convenient fluid dynamic regime. To achieve final permeability, the primary and secondary fibres of the pappus have evolved with complex weaving; this maximises the drag force (i.e., the drag coefficient), and the pappus operates in an "optimal" state. We used computational fluid dynamics (CFD) simulations to compute the seed drag coefficient and compare it with data obtained from drop experiments. The permeability of the parachute was estimated from microscope images. Our simulations reveal three flow regimes in which the parachute can operate according to its permeability. These flow regimes impact the stability of the parachute and its drag coefficient. From the permeability measurements and drop experiments, we show how the seeds operate very close to the optimal case. The porosity of the textile appears to be an appropriate solution to achieve a lightweight structure that allows a low terminal velocity, a stable flight and a very efficient parachute for the velocity at which it operates.

  3. Pondberry (Lindera   melissifolia, Lauraceae) seed and seedling dispersers and predators

    Science.gov (United States)

    Andreza M. Martins; Fernanda M. Abilio; Plinio Gonçalves de Oliveira; Raquel Partelli Feltrin; Fernanda Scheffer Alves de Lima; Priscilla de O. Antonelli; Daniela Teixeira Vilela; Carl G. Smith III; Collin Tidwell; Paul Hamel; Margaret Devall; Kristina Connor; Theodor Leininger; Nathan Schiff; A. Dan Wilson

    2015-01-01

    Pondberry (Lindera melissifolia(Walter) Blume) is an endangered dioecious, clonal shrub that grows in periodically flooded forests of the southeastern United States. The probability of survival of dispersed pondberry seeds and new germinants is unknown, but few seedlings are noted in the forest. This study was undertaken to: (1) identify herbivores...

  4. Stability and generalization in seed dispersal networks: a case study of frugivorous fish in Neotropical wetlands.

    Science.gov (United States)

    Correa, Sandra Bibiana; Arujo, Joisiane K; Penha, Jerry; Nunes da Cunha, Catia; Bobier, Karen E; Anderson, Jill T

    2016-08-31

    When species within guilds perform similar ecological roles, functional redundancy can buffer ecosystems against species loss. Using data on the frequency of interactions between fish and fruit, we assessed whether co-occurring frugivores provide redundant seed dispersal services in three species-rich Neotropical wetlands. Our study revealed that frugivorous fishes have generalized diets; however, large-bodied fishes had greater seed dispersal breadth than small species, in some cases, providing seed dispersal services not achieved by smaller fish species. As overfishing disproportionately affects big fishes, the extirpation of these species could cause larger secondary extinctions of plant species than the loss of small specialist frugivores. To evaluate the consequences of frugivore specialization for network stability, we extracted data from 39 published seed dispersal networks of frugivorous birds, mammals and fish (our networks) across ecosystems. Our analysis of interaction frequencies revealed low frugivore specialization and lower nestedness than analyses based on binary data (presence-absence of interactions). In that case, ecosystems may be resilient to loss of any given frugivore. However, robustness to frugivore extinction declines with specialization, such that networks composed primarily of specialist frugivores are highly susceptible to the loss of generalists. In contrast with analyses of binary data, recently developed algorithms capable of modelling interaction strengths provide opportunities to enhance our understanding of complex ecological networks by accounting for heterogeneity of frugivore-fruit interactions. © 2016 The Author(s).

  5. Seed dispersal networks in the Galápagos and the consequences of alien plant invasions

    DEFF Research Database (Denmark)

    Heleno, R. H.; Olesen, Jens Mogens; Nogales, M.

    2013-01-01

    , followed by small ground finch, two mockingbirds, the giant tortoise and two insectivorous birds. Most animals dispersed alien seeds, but these formed a relatively small proportion of the interactions. Nevertheless, the integration of aliens was higher in the island that has been invaded for longest...

  6. Defoliation effects on seed dispersal and seedling recruitment in a tropical rain forest understorey palm

    NARCIS (Netherlands)

    Lent, van J.; Hernandez-Barrios, J.C.; Anten, N.P.R.; Martinez-Ramos, M.

    2014-01-01

    1. Assessing the demographic effects of leaf area losses in perennial plants is important to determine population resilience to natural and anthropogenic disturbances. Yet, while impacts of defoliation on vital rates of adult plants have been well documented, consequences for seed dispersal and

  7. Seed dispersal by fishes in tropical and temperate fresh waters: The growing evidence

    NARCIS (Netherlands)

    Horn, M.H.; Correa, S.B.; Parolin, P.; Pollux, B.J.A.; Anderson, J.T.; Lucas, C.; Widmann, P.; Tjiu, A.; Galetti, M.; Goulding, M.

    2011-01-01

    Fruit-eating by fishes represents an ancient (perhaps Paleozoic) interaction increasingly regarded as important for seed dispersal (ichthyochory) in tropical and temperate ecosystems. Most of the more than 275 known frugivorous species belong to the mainly Neotropical Characiformes (pacus, piranhas)

  8. Edge effect on post-dispersal artificial seed predation in the southeastern Amazonia, Brazil

    Directory of Open Access Journals (Sweden)

    G. Penido

    Full Text Available This paper evaluates the post-dispersal artificial seed predation rates in two areas of the southeastern Amazon forest-savanna boundary, central Brazil. We conducted the survey in a disturbance regime controlled research site to verify if exists an edge effect in these rates and if the disturbance (in this case annual fire and no fire affects seed predation. We placed 800 peanuts seeds in each area at regular distance intervals from the fragment`s edge. Data were analyzed by a likelihood ratio model selection in generalized linear models (GLM. The complete model (with effects from edge distance and site and its interaction was significative (F3=4.43; p=0.005. Seeds had a larger predation rates in fragment’s interior in both areas, but in the controlled area (no disturbance this effect was less linear. This suggests an edge effect for post-dispersal seed predation, and that disturbances might alter these effects. Even if we exclude the site effect (grouping both areas together there is still a strong edge effect on seed predation rates (F3=32.679; p>0.001. We did not verify predator’s species in this study; however, the presence of several species of ants was extremely common in the seeds. The detection of an edge effect in only a short survey time suggests that there is heterogeneity in predation rates and that this variation might affect plant recruitment in fragmented areas of the Amazon forest. Henceforth, this seed predation should be taken in consideration in reforestation projects, where the main source of plants species is from seed distribution.

  9. Edge effect on post-dispersal artificial seed predation in the southeastern Amazonia, Brazil.

    Science.gov (United States)

    Penido, G; Ribeiro, V; Fortunato, D S

    2015-05-01

    This paper evaluates the post-dispersal artificial seed predation rates in two areas of the southeastern Amazon forest-savanna boundary, central Brazil. We conducted the survey in a disturbance regime controlled research site to verify if exists an edge effect in these rates and if the disturbance (in this case annual fire and no fire) affects seed predation. We placed 800 peanuts seeds in each area at regular distance intervals from the fragment`s edge. Data were analyzed by a likelihood ratio model selection in generalized linear models (GLM). The complete model (with effects from edge distance and site and its interaction) was significative (F3=4.43; p=0.005). Seeds had a larger predation rates in fragment's interior in both areas, but in the controlled area (no disturbance) this effect was less linear. This suggests an edge effect for post-dispersal seed predation, and that disturbances might alter these effects. Even if we exclude the site effect (grouping both areas together) there is still a strong edge effect on seed predation rates (F3=32.679; p>0.001). We did not verify predator's species in this study; however, the presence of several species of ants was extremely common in the seeds. The detection of an edge effect in only a short survey time suggests that there is heterogeneity in predation rates and that this variation might affect plant recruitment in fragmented areas of the Amazon forest. Henceforth, this seed predation should be taken in consideration in reforestation projects, where the main source of plants species is from seed distribution.

  10. Evolution of seed dispersal in the Cerrado biome: ecological and phylogenetic considerations

    Directory of Open Access Journals (Sweden)

    Marcelo Kuhlmann

    2016-01-01

    Full Text Available ABSTRACT The investigation of the phylogeny of a group of organisms has the potential to identify ecological and evolutionary processes that have been occurring within a community. Seed dispersal is a key process in the life cycle of vegetation and reflects different reproductive strategies of plants to a set of ecological and evolutionary factors. Knowing the dispersal syndromes and fruits types of a plant community may help elucidate plant-animal interactions and colonization strategies of plants. We investigated dispersal syndromes and fruit types in Cerrado formations as a parameter for understanding the evolution of angiosperm reproductive strategies in this mega-diverse tropical biome. To do this we identified and mapped the distribution of different parameters associated with seed dispersal on a phylogeny of Cerrado angiosperms genera and tested the presence of phylogenetic signal. The results showed that there were strong relationships between fruit types, seed dispersal strategies and vegetation life forms and that these traits were closely related to angiosperms phylogeny and, together, contribute to the evolution of plants in the forest, savanna and grassland formations of the Cerrado biome.

  11. Pollination and seed dispersal of Aquilaria sinensis (Lour. Gilg (Thymelaeaceae: An economic plant species with extremely small populations in China

    Directory of Open Access Journals (Sweden)

    Gao Chen

    2016-10-01

    Full Text Available Pollination and seed dispersal in angiosperms have long been investigated in order to understand the coevolution of plants and animals. However, the signals from flowers and/or seeds to attract pollinators and/or seed dispersers have received comparatively little attention. In this study, the pollination biology and seed dispersal of the vulnerable agarwood plant Aquilaria sinensis (Lour. Gilg, a traditional medicinal plant in China, was studied in its natural distribution range. The reproductive tactics of A. sinensis were studied in detail by employing various tests dealing with fruit set and also seed dispersal. Dynamic headspace extraction followed by GC-MS analysis was also performed in order to reveal the composition of floral scent. The results showed that noctuids and pyralids are the most effective pollinators of pollinator-dependent A. sinensis. The main compounds of the floral scent were (E, E-α-Farnesene (61.9 ± 3.2%, trans-Ocimene (16.6 ± 1.2%, and Benzyl salicylate (4.6 ± 1.1%. The results obtained from seed dispersal experiments indicate that hornets are effective seed dispersers and they may play an important role in long-distance seed dispersal of A. sinensis. Based on our findings, we recommend several protection methods for this threatened agarwood plant in China.

  12. Red fox ( Vulpes vulpes L.) favour seed dispersal, germination and seedling survival of Mediterranean Hackberry ( Celtis australis L.)

    Science.gov (United States)

    Juan, Traba; Sagrario, Arrieta; Jesús, Herranz; Cristina, Clamagirand M.

    2006-07-01

    Seeds of the Mediterranean Hackberry Celtis australis are often encountered in fox faeces. In order to evaluate the effect of gut transit on the size of seeds selected, the rates and speed of germination and on the survival of the seedlings, Mediterranean Hackberry seeds from fox faeces were germinated in a greenhouse. The results were compared with those of seeds taken from ripe, uneaten fruits. Fox-dispersed seeds were smaller and lighter than the control ones and had higher (74% vs. 57%) and more rapid germination (74.5 days vs. 99.2 days). Seedlings from fox-dispersed seeds showed significantly greater survival by the end of the study period (74.1% vs. 43.6%) than the control ones. Survival in seedlings from fox-dispersed seeds was related to germination date, late seedlings showing poorer survival. This relationship was not observed away in the control seedlings. Seed mass did not affect seedling survival. Seedling arising from fox-dispersed seeds grew faster than control ones. These results suggest that fox can play a relevant role as seed disperser of Mediterranean Hackberry.

  13. Spatial variation in post-dispersal seed removal in an Atlantic forest: Effects of habitat, location and guilds of seed predators

    Science.gov (United States)

    Christianini, Alexander V.; Galetti, Mauro

    2007-11-01

    Studies of post-dispersal seed removal in the Neotropics have rarely examined the magnitude of seed removal by different types of granivores. The relative impact of invertebrates, small rodents, and birds on seed removal was investigated in a 2,178 ha Atlantic forest fragment in southeastern Brazil. We used popcorn kernels ( Zea mays—Poaceae) to investigate seed removal in a series of selective exclosure treatments in a replicated, paired design experiment that included forest understory, gaps, and forest edge sites. We recorded the vegetation around the experimental seed stations in detail in order to evaluate the influence of microhabitat traits on seed removal. Vertebrate granivores (rodents and birds) were surveyed to determine whether granivore abundance was correlated with seed removal levels. Seed removal varied spatially and in unpredictable ways at the study site. Seed encounter and seed use varied with treatments, but not with habitat type. However, seed removal by invertebrates was negatively correlated with gap-related traits, which suggested an avoidance of large gaps by granivorous ants. The abundance of small mammals was remarkably low, but granivorous birds (tinamous and doves) were abundant at the study site. Birds were the main seed consumers in open treatments, but there was no correlation between local granivorous bird abundance and seed removal. These results emphasize the stochastic spatial pattern of seed removal, and, contrary to previous studies, highlight the importance of birds as seed predators in forest habitats.

  14. Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages

    NARCIS (Netherlands)

    Caughlin, T.T.; Ferguson, J.M.; Lichstein, J.W.; Zuidema, P.A.; Bunyavejchewin, S.; Levey, D.J.

    2015-01-01

    Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing

  15. Anthropogenic disturbance reduces seed-dispersal services for myrmecochorous plants in the Brazilian Caatinga.

    Science.gov (United States)

    Leal, Laura C; Andersen, Alan N; Leal, Inara R

    2014-01-01

    Anthropogenic disturbance can have important indirect effects on ecosystems by disrupting species interactions. Here we examine the effects of anthropogenic disturbance on distance dispersal by ants for the diaspores of myrmecochorous Euphorbiaceae in Brazilian Caatinga. Rates of diaspore removal and distances removed of Croton sonderianus and Jatropha mollissima were observed at 24 sites ranging from low to very high disturbance (primarily grazing by livestock, hunting and firewood collection). Despite a large number of seed-disperser ant species, there were only two species providing high-quality distance-dispersal services, Dinoponera quadriceps (40% of all observed seed removals) and Ectatomma muticum (33%). D. quadriceps was responsible for 97% of all removals >2 m, and 100% of all removals >5 m. Removal rates did not vary with disturbance for C. sonderianus (small elaiosome), but declined with increasing disturbance for J. mollissima (large elaiosome). The number of removals by Ectatomma was highest at intermediate levels of disturbance, whereas those by Dinoponera decreased systematically with increasing levels of disturbance. Mean dispersal distance was four times higher at sites experiencing low disturbance, where removals >5 m represented a third of all removal events, compared with very highly disturbed sites, where no removals >5 m were observed. Despite high overall diversity there is very limited functional redundancy in disperser ant species, resulting in low disperser resilience in relation to disturbance. This is likely to have important implications for recruitment by myrmecochorous plants, and therefore on vegetation composition and structure, at sites subject to high anthropogenic disturbance.

  16. Partitioning of seed dispersal services between birds and bats in a fragment of the Brazilian Atlantic Forest

    Directory of Open Access Journals (Sweden)

    Raissa Sarmento

    2014-06-01

    Full Text Available Community-level network studies suggest that seed dispersal networks may share some universal properties with other complex systems. However, most of the datasets used so far in those studies have been strongly biased towards temperate birds, including not only dispersers, but also seed predators. Recent evidence from multi-taxon networks suggests that seed dispersal networks are not all alike and may be more complex than previously thought. Here, we used network theory to evaluate seed dispersal in a strongly impacted Atlantic Forest fragment in northeastern Brazil, where bats and birds are the only extant dispersers. We hypothesized that the seed dispersal network should be more modular then nested, and that the dispersers should segregate their services according to dispersal syndromes. Furthermore, we predicted that bat and bird species that are more specialized in frugivory would be more important for maintaining the network structure. The mixed network contained 56 plant species, 12 bat species, and eight bird species, and its structure was more modular (M = 0.58 then nested (NODF = 0.21 compared with another multi-taxon network and 21 single-taxon networks (with either bats or birds. All dispersed fruits had seeds smaller than 9 mm. Bats dispersed mainly green fruits, whereas birds dispersed fruits of various colors. The network contained eight modules: five with birds only, two with bats only, and one mixed. Most dispersers were peripheral, and only specialized frugivores acted as hubs or connectors. Our results strongly support recent studies, suggesting that seed dispersal networks are complex mosaics, where different taxa form separate modules with different properties, which in turn play complementary roles in the maintenance of the associated ecosystem functions and services.

  17. Feeding assemblages of mammals at fruiting Dipteryx panamensis (Papilionaceae) trees in Panama: seed predation, dispersal, and parasitism

    OpenAIRE

    Bonaccorso, Frank J.; Glanz, William E.; Sandford, Clark M.

    2016-01-01

    Fruiting almendro trees, Dipteryx panamensis, are visited by sixteen species of mammals that eat the fruits exocarp or seed. Seeds are susceptible to predation by granivorous rodents and peccaries. Most mammals that visit Dipteryx trees act as commensals·, eating only the fleshy exocarp and dropping the endocarp with its enclosed seed below the parent tree. So me primates, tayras, coatis, and kinkajous occasionally disperse Dipteryx seeds, but only Artibeus lituratus, Dasyprocta punctata, and...

  18. Effects of climate change and seed dispersal on airborne ragweed pollen loads in Europe

    Science.gov (United States)

    Hamaoui-Laguel, Lynda; Vautard, Robert; Liu, Li; Solmon, Fabien; Viovy, Nicolas; Khvorostyanov, Dmitry; Essl, Franz; Chuine, Isabelle; Colette, Augustin; Semenov, Mikhail A.; Schaffhauser, Alice; Storkey, Jonathan; Thibaudon, Michel; Epstein, Michelle M.

    2015-08-01

    Common ragweed (Ambrosia artemisiifolia) is an invasive alien species in Europe producing pollen that causes severe allergic disease in susceptible individuals. Ragweed plants could further invade European land with climate and land-use changes. However, airborne pollen evolution depends not only on plant invasion, but also on pollen production, release and atmospheric dispersion changes. To predict the effect of climate and land-use changes on airborne pollen concentrations, we used two comprehensive modelling frameworks accounting for all these factors under high-end and moderate climate and land-use change scenarios. We estimate that by 2050 airborne ragweed pollen concentrations will be about 4 times higher than they are now, with a range of uncertainty from 2 to 12 largely depending on the seed dispersal rate assumptions. About a third of the airborne pollen increase is due to on-going seed dispersal, irrespective of climate change. The remaining two-thirds are related to climate and land-use changes that will extend ragweed habitat suitability in northern and eastern Europe and increase pollen production in established ragweed areas owing to increasing CO2. Therefore, climate change and ragweed seed dispersal in current and future suitable areas will increase airborne pollen concentrations, which may consequently heighten the incidence and prevalence of ragweed allergy.

  19. Intraspecific variation in fruit-frugivore interactions: effects of fruiting neighborhood and consequences for seed dispersal.

    Science.gov (United States)

    Guerra, Tadeu J; Dayrell, Roberta L C; Arruda, André J; Dáttilo, Wesley; Teixido, Alberto L; Messeder, João V S; Silveira, Fernando A O

    2017-10-01

    The extent of specialization/generalization continuum in fruit-frugivore interactions at the individual level remains poorly explored. Here, we investigated the interactions between the Neotropical treelet Miconia irwinii (Melastomataceae) and its avian seed dispersers in Brazilian campo rupestre. We built an individual-based network to derive plant degree of interaction specialization regarding disperser species. Then, we explored how intraspecific variation in interaction niche breadth relates to fruit availability on individual plants in varying densities of fruiting conspecific neighbors, and how these factors affect the quantity of viable seeds dispersed. We predicted broader interaction niche breadths for individuals with larger fruit crops in denser fruiting neighborhoods. The downscaled network included nine bird species and 15 plants, which varied nearly five-fold in their degree of interaction specialization. We found positive effects of crop size on visitation and fruit removal rates, but not on degree of interaction specialization. Conversely, we found that an increase in the density of conspecific fruiting neighbors both increased visitation rate and reduced plant degree of interaction specialization. We suggest that tracking fruit-rich patches by avian frugivore species is the main driver of density-dependent intraspecific variation in plants' interaction niche breadth. Our study shed some light on the overlooked fitness consequences of intraspecific variation in interaction niches by showing that individuals along the specialization/generalization continuum may have their seed dispersed with similar effectiveness. Our study exemplifies how individual-based networks linking plants to frugivore species that differ in their seed dispersal effectiveness can advance our understanding of intraspecific variation in the outcomes of fruit-frugivore interactions.

  20. Domestic honeybees affect the performance of pre-dispersal seed predators in an alpine meadow.

    Science.gov (United States)

    Xi, Xinqiang; Dong, Yuran; Tian, Xingjun; Xu, Haigen; Zhou, Qingping; Niklas, Karl J; Sun, Shucun

    2018-03-01

    Flowering plants interact simultaneously with mutualistic pollinators and antagonistic herbivores such that plant-mediated interactions between pollinators and herbivores must exist. Although the effects of herbivores on pollinator behavior have been investigated extensively, the effect of pollinators on herbivore performance has seldom been explored. We hypothesized that insect pollinators could improve the survival and growth of pre-dispersal seed predators by increasing seed production. We tested this hypothesis along three transects radiating from well-established apiaries in an alpine meadow by supplementing pollination in sites close to and distant from apiaries and subsequently examining seed production of the dominant nectariferous plant species Saussurea nigrescens (Asteraceae) and the performance of three dominant pre-dispersal seed predators (tephritid fly species). Pollen supplementation (1) significantly increased seed set and mass of developed seed per capitulum (i.e., flowerhead) in the distant but not the close sites, (2) did not change the survival and growth rates of the smaller-bodied species (Tephritis femoralis and Campiglossa nigricauda) at either site, but (3) improved the performance of the larger-bodied seed predator (Terellia megalopyge) at distant sites but not close sites. In addition, the larger-bodied tephritid fly showed higher infestation rates and relative abundance in the close sites than in the distant sites, whereas the smaller-bodied species had lower relative abundances in the close sites and similar infestation rates in both site types. These observations demonstrate contrasting effects of plant mutualists on the performance of antagonists with potential consequences for population sizes of insect herbivores.

  1. Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area.

    Science.gov (United States)

    Francisco, M R; Lunardi, V O; Galetti, M

    2007-11-01

    Several plant characteristics, such as fruit production, nutrient reward, secondary compounds, and fruit color display, affect fruit choice by birds. On the other hand, several bird attributes affect their efficiency as dispersers. Here we investigate the ornithochoric seed dispersal of Pera glabrata Schott (Euphorbiaceae) in a cerrado fragment in southeastern Brazil. A set of bird attributes, such as frequency of visits, number of diaspores eaten, time spent foraging, methods of taking and handling the diaspores and agonistic interactions were analyzed in order to infer about the potential of each species to act as a seed disperser. Birds were the unique seed dispersers of these oil-rich diaspores. We observed 414 bird visits during 60 hours of focal observations in five trees from December 1999 to January 2000. Twenty bird species from seven families ate the diaspores of P. glabrata, but only 14 species were considered potential seed dispersers because they swallowed the diaspores, increasing the probabilities for the seeds to be defecated and/or regurgitated away from the parent trees. The main potential seed dispersers were: Turdus leucomelas (Muscicapidae), Dacnis cayana (Emberizidae), Colaptes melanochloros (Picidae) and Elaenia spp. (Tyrannidae). We did not find any significant seasonal change in the number of visits on the fruiting trees throughout the day. We also did not find any relation between the number of visits per tree and fruit production. The most effective seed dispersers of P. glabrata were generalist birds, which have a high visiting rate, high fruit consumption rate, and spend short periods on the plants. The large number of species recorded as potential seed dispersers of P. glabrata, being most of them very abundant even in Brazilian disturbed areas, may guarantee seed dispersal of this plant in small fragments and regenerating areas.

  2. Ecological consequences of primary and secondary seed dispersal on seed and seedling fate of Dipteryx oleifera (Fabaceae

    Directory of Open Access Journals (Sweden)

    Javier Ruiz

    2010-09-01

    Full Text Available The relative contributions of primary and secondary seed dispersal to plant demography have received little investigation. Evidence on these seed dispersal types, on seed fate and seedling recruitment of the tropical rain forest tree Dipteryx oleifera, is presented. The study was conducted in a 6.37ha permanent plot where seeds and seedlings were located and tagged for the 2007 cohort. A total of 2 814 seeds were threaded and their fate was followed one year after germination. Primary seed dispersal by bats protected seeds from insect larval predation below the adult tree. Bats congregated seeds in bat seed piles located at a mean distance of 40.94±1.48m from the nearest adult individual of D. oleifera. Terrestrial vertebrates congregated seeds in caches located 41.90±2.43m from the nearest adult individual of D. oleifera. The results of the fitted proportional hazard model suggested that primary seed dispersal decreased seed hazard probability by 1.12% for each meter from the adult conspecific (pPresentamos evidencia de la contribución relativa de la dispersión primaria y secundaria de semillas en la suerte que corren las mismas y en el reclutamiento de plántulas de la especie de bosque húmedo tropical Dipteryx oleifera. Este estudio fue realizado en una parcela permanente de 6.37 ha en la que semillas y plántulas del cohorte del 2007 fueron localizadas y mapeadas. Etiquetamos 2 814 semillas para evaluar su suerte un año después de la germinación. Encontramos que la dispersión primaria por murciélagos libera a las semillas de la depredación bajo la copa del árbol adulto causada por la fase larval de un insecto. Los murciélagos dispersan semillas bajo la copa de palmas usadas como comederos, localizados a 40.94±1.48m del árbol de D. oleifera más cercano y vertebrados terrestres congregaran las semillas en caches localizados aproximadamente a 41.90±2.43m del árbol de D. oleifera. Un modelo proporcional de riesgos fue ajustado

  3. Evaluating realized seed dispersal across fragmented tropical landscapes: a two-fold approach using parentage analysis and the neighbourhood model.

    Science.gov (United States)

    Ismail, Sascha A; Ghazoul, Jaboury; Ravikanth, Gudasalamani; Kushalappa, Cheppudira G; Uma Shaanker, Ramanan; Kettle, Chris J

    2017-05-01

    Despite the importance of seed dispersal for survival of plant species in fragmented landscapes, data on seed dispersal at landscape scales remain sparse. Effective seed dispersal among fragments determines recolonization and plant species persistence in such landscapes. We present the first large-scale (216-km 2 ) direct estimates of realized seed dispersal of a high-value timber tree (Dysoxylum malabaricum) across an agro-forest landscape in the Western Ghats, India. Based upon an exhaustive inventory of adult trees and a sample of 488 seedlings all genotyped at 10 microsatellite loci, we estimated realized seed dispersal using parentage analysis and the neighbourhood model. Our estimates found that most realized seed dispersal was within 200 m, which is insufficient to effectively bridge the distances between forest patches. We conclude that using mobility of putative animal dispersers can be misleading when estimating tropical tree species vulnerability to habitat fragmentation. This raises serious concerns about the potential of many tropical trees to recolonize isolated forest patches where high-value tree species have already been removed. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  4. Relocation of Croton sonderianus (Euphorbiaceae) seeds by Pheidole fallax Mayr (Formicidae): a case of post-dispersal seed protection by ants?

    Science.gov (United States)

    Lôbo, D; Tabarelli, M; Leal, I R

    2011-01-01

    Although seed dispersal by ants might reduce seed predation near the parent plants, predation on discarded seeds clustered on nest refuse piles may reduce any initial benefit provided by seed removal. Here we examine the fate of Croton sonderianus seeds that were discarded by Pheidole fallax Mayr ants on their nest refuses in caatinga vegetation of northeast Brazil. We collected all seeds discarded in refuse piles of 20 nests and within a radius of 50 cm from their borders, and examined them for evidence of predation. A total of 3,017 seeds were recorded either located in the P. fallax refuse piles (89.1%) or nest vicinity (10.9%). Predation was three fold higher in nest vicinity as compared to refuse piles. By removing seeds from beneath parent plants and relocating then to refuse piles, P. fallax is possibly providing double protection services for C. sonderianus seeds. Our findings represent the first evidence for predator-avoidance as benefit for plants resulting from ant seed-dispersal in the neotropics.

  5. Seed dispersal and spatial distribution of Attalea geraensis (Arecaceae) in two remnants of Cerrado in Southeastern Brazil

    Science.gov (United States)

    Bonjorne de Almeida, Lilian; Galetti, Mauro

    2007-09-01

    The seed dispersal system of Attalea geraensis (Arecaceae), an acaulescent palm, was investigated during one year in two Cerrado fragments in the state of São Paulo, southeastern Brazil. A. geraensis had inflorescences and infrutescences throughout the year. Two scatter-hoarding rodents (the spiny rat, Clyomys bishopi and agoutis, Dasyprocta azarae) were identified as seed predators/dispersers, able to move seeds up to 30 m from the palms, although most of the fruits (57.5%) were dispersed less than 2 m. The removal rates were high and after 20 days, 97.2% of the fruits were removed. Fruit fate was not related to fruit mass, length and diameter. The application of Morisita's index showed a more clumped distribution of adults in the smaller fragment, probably because of the absence of agoutis. Higher seed removal by rodents in the large Cerrado remnant may decrease seed predation by beetles.

  6. Quantifying Microstegium vimineum seed movement by non-riparian water dispersal using an ultraviolet-marking based recapture method.

    Directory of Open Access Journals (Sweden)

    Daniel R Tekiela

    Full Text Available Microstegium vimineum is a shade tolerant annual C4 invasive grass in the Eastern US, which has been shown to negatively impact species diversity and succession in hardwood forests. To date, empirical studies have shown that population expansion is limited to <1 m yr(-1, which is largely driven by gravity dispersal. However, this likely does not fully account for all mechanisms of population-scale dispersal as we observe greater rates of population expansion. Though water, both riparian and non-riparian water (i.e., ephemeral overland flow, have been speculated mechanisms for M. vimineum dispersal, few studies have empirically tested this hypothesis. We designed an experiment along the slopes of a Southwest Virginia hardwood forest to test the role of non-riparian water on local seed dispersal. We developed a seed marking technique by coating each seed with an ultraviolet (UV powder that did not affect buoyancy to aid in situ seed recapture. Additionally, a new image analysis protocol was developed to automate seed identification from UV photos. Total seed mobility (summation of individual seed movement within each transect was positively correlated with precipitation. Over a period of one month with 52.32 mm of precipitation, the maximum dispersal distance of any single recaptured seed was 2.4 m, and the average distance of dispersed seed was 0.21±0.04 m. This is the first quantitative evidence of non-riparian water dispersal in a forest understory, which accounts for an additional pathway of population expansion.

  7. Pre-dispersal seed predation in a species-rich forest community: Patterns and the interplay with determinants

    Science.gov (United States)

    Yue Xu; Zehao Shen; Daoxin Li; Qinfeng Guo

    2015-01-01

    Pre-dispersal seed predation (PDSP) is commonly observed in woody plants, and recognized as a driver of seed production variability that is critical for successful regeneration. Earlier studies on PDSP and its determinants were mostly species specific, with community- level PDSP rarely estimated; and the interactions between the temporal...

  8. Simple Methodologies to Estimate the Energy Amount Stored in a Tree Due to an Explosive Seed Dispersal Mechanism

    Science.gov (United States)

    do Carmo, Eduardo; Hönnicke, Marcelo Goncalves

    2018-01-01

    There are different forms to introduce/illustrate the energy concepts for the basic physics students. The explosive seed dispersal mechanism found in a variety of trees could be one of them. Sibipiruna trees carry out fruits (pods) who show such an explosive mechanism. During the explosion, the pods throw out seeds several meters away. In this…

  9. Evidence for herbaceous seed dispersal by small-bodied fishes in a Pantanal seasonal wetland

    Directory of Open Access Journals (Sweden)

    RML Silveira

    Full Text Available We analysed the germination of seeds after their passage through the digestive tract of small floodplain fishes. Samples were collected in five open flooded fields of the northern Pantanal in March 2011. All fishes were sacrificed and their intestinal contents were removed. The fecal material was weighed and stored at 4°C in a GF/C filter wrapped in aluminum foil. The material was then transferred to a receptacle containing sterilised soil from the sampling area. The fecal samples were kept in a germination chamber for 68 days and then transferred to a greenhouse for another 67 days. We collected a total of 45 fish species and 1014 individuals which produced a total amount of 32g of fresh fecal mass and 11 seedlings. We were able to identify six seedlings: two Banara arguta, two Steinchisma laxa, one Hymenachne amplexicaulis and one Luziola sp.. The fish species that produced samples with seedlings were Astyanax assuncionensis, Metynnis mola, Plesiolebias glaucopterus, Acestrorhyncus pantaneiro and Anadoras wendelli. With the exception of B. arguta the remaining plant species and all fish species were not known to be associated with the seed dispersal process of these plants. We found a ratio of 0.435 seedlings.g–1 of fresh fecal material, which is 100 times higher than the amount of seedlings encountered in fresh soil mass (92,974 grams in seed bank studies conducted in the same study area. In particular, Astyanax assuncionensis and Metynnis mola were among the most frequent and most abundant fish taxa in the area. Together with the high seed concentration in the fish fecal material, this evidence allows us to conclude that such fish species may play an important role in seed dispersal in the herbaceous plants of the Pantanal.

  10. Evidence for herbaceous seed dispersal by small-bodied fishes in a Pantanal seasonal wetland.

    Science.gov (United States)

    Silveira, R M L; Weiss, B

    2014-08-01

    We analysed the germination of seeds after their passage through the digestive tract of small floodplain fishes. Samples were collected in five open flooded fields of the northern Pantanal in March 2011. All fishes were sacrificed and their intestinal contents were removed. The fecal material was weighed and stored at 4°C in a GF/C filter wrapped in aluminum foil. The material was then transferred to a receptacle containing sterilised soil from the sampling area. The fecal samples were kept in a germination chamber for 68 days and then transferred to a greenhouse for another 67 days. We collected a total of 45 fish species and 1014 individuals which produced a total amount of 32 g of fresh fecal mass and 11 seedlings. We were able to identify six seedlings: two Banara arguta, two Steinchisma laxa, one Hymenachne amplexicaulis and one Luziola sp.. The fish species that produced samples with seedlings were Astyanax assuncionensis, Metynnis mola, Plesiolebias glaucopterus, Acestrorhyncus pantaneiro and Anadoras wendelli. With the exception of B. arguta the remaining plant species and all fish species were not known to be associated with the seed dispersal process of these plants. We found a ratio of 0.435 seedlings.g-1 of fresh fecal material, which is 100 times higher than the amount of seedlings encountered in fresh soil mass (92,974 grams) in seed bank studies conducted in the same study area. In particular, Astyanax assuncionensis and Metynnis mola were among the most frequent and most abundant fish taxa in the area. Together with the high seed concentration in the fish fecal material, this evidence allows us to conclude that such fish species may play an important role in seed dispersal in the herbaceous plants of the Pantanal.

  11. Noise pollution alters ecological services: enhanced pollination and disrupted seed dispersal.

    Science.gov (United States)

    Francis, Clinton D; Kleist, Nathan J; Ortega, Catherine P; Cruz, Alexander

    2012-07-22

    Noise pollution is a novel, widespread environmental force that has recently been shown to alter the behaviour and distribution of birds and other vertebrates, yet whether noise has cumulative, community-level consequences by changing critical ecological services is unknown. Herein, we examined the effects of noise pollution on pollination and seed dispersal and seedling establishment within a study system that isolated the effects of noise from confounding stimuli common to human-altered landscapes. Using observations, vegetation surveys and pollen transfer and seed removal experiments, we found that effects of noise pollution can reverberate through communities by disrupting or enhancing these ecological services. Specifically, noise pollution indirectly increased artificial flower pollination by hummingbirds, but altered the community of animals that prey upon and disperse Pinus edulis seeds, potentially explaining reduced P. edulis seedling recruitment in noisy areas. Despite evidence that some ecological services, such as pollination, may benefit indirectly owing to noise, declines in seedling recruitment for key-dominant species such as P. edulis may have dramatic long-term effects on ecosystem structure and diversity. Because the extent of noise pollution is growing, this study emphasizes that investigators should evaluate the ecological consequences of noise alongside other human-induced environmental changes that are reshaping human-altered landscapes worldwide.

  12. Seed dispersal distributions resulting from landscape-dependent daily movement behavior of a key vector species, Anas platyrhynchos

    NARCIS (Netherlands)

    Kleyheeg, Erik; Treep, J.; de Jager, M.; Nolet, B.A.; Soons, M.B.

    2017-01-01

    Dispersal via animals (zoochory) is a primary mechanism for seed exchange between habitat patches. Recent studies have established that many plant species can survive waterbird gut passage. To quantify the patterns and consequences of waterbird-mediated dispersal, information on ingestion and gut

  13. Disentangling the drivers of reduced long-distance seed dispersal by birds in an experimentally fragmented landscape.

    Science.gov (United States)

    Uriarte, María; Anciães, Marina; da Silva, Mariana T B; Rubim, Paulo; Johnson, Erik; Bruna, Emilio M

    2011-04-01

    Seed dispersal is a crucial component of plant population dynamics. Human landscape modifications, such as habitat destruction and fragmentation, can alter the abundance of fruiting plants and animal dispersers, foraging rates, vector movement, and the composition of the disperser community, all of which can singly or in concert affect seed dispersal. Here, we quantify and tease apart the effects of landscape configuration, namely, fragmentation of primary forest and the composition of the surrounding forest matrix, on individual components of seed dispersal of Heliconia acuminata, an Amazonian understory herb. First we identified the effects of landscape configuration on the abundance of fruiting plants and six bird disperser species. Although highly variable in space and time, densities of fruiting plants were similar in continuous forest and fragments. However, the two largest-bodied avian dispersers were less common or absent in small fragments. Second, we determined whether fragmentation affected foraging rates. Fruit removal rates were similar and very high across the landscape, suggesting that Heliconia fruits are a key resource for small frugivores in this landscape. Third, we used radiotelemetry and statistical models to quantify how landscape configuration influences vector movement patterns. Bird dispersers flew farther and faster, and perched longer in primary relative to secondary forests. One species also altered its movement direction in response to habitat boundaries between primary and secondary forests. Finally, we parameterized a simulation model linking data on fruit density and disperser abundance and behavior with empirical estimates of seed retention times to generate seed dispersal patterns in two hypothetical landscapes. Despite clear changes in bird movement in response to landscape configuration, our simulations demonstrate that these differences had negligible effects on dispersal distances. However, small fragments had reduced densities

  14. Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale.

    Science.gov (United States)

    de la Peña, Eduardo; Bonte, Dries

    2014-08-01

    Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The strengths and directions of these responses have been scarcely addressed in the literature. Using Taraxacum officinale, the root-feeding nematode Meloidogyne hapla and the locust Schistocerca gregaria as a model species, we examined to what degree above- and belowground herbivory affect (1) plant growth responses, (2) the induction of plant defensive traits, that is, leaf trichomes, and (3) changes in dispersal-related seed traits and seed germination. We compared the performance of plants originating from different populations to address whether plant responses are conserved across putative different genotypes. Overall, aboveground herbivory resulted in increased plant biomass. Root herbivory had no effect on plant growth. Plants exposed to the two herbivores showed fewer leaf trichomes than plants challenged only by one herbivore and consequently experienced greater aboveground herbivory. In addition, herbivory had effects that reached beyond the individual plant by modifying seed morphology, producing seeds with longer pappus, and germination success.

  15. Phenology, seed dispersal and difficulties in natural recruitment of the canopy tree Pachira quinata (Malvaceae

    Directory of Open Access Journals (Sweden)

    Maria Clara Castellanos

    2011-06-01

    Full Text Available Life history and recruitment information of tropical trees in natural populations is scarce even for important commercial species. This study focused on a widely exploited Neotropical canopy species, Pachiraquinata (Malvaceae, at the southernmost, wettest limit of its natural distribution, in the Colombian Amazonia. We studied phenological patterns, seed production and natural densities; assessed the importance of seed dispersal and density-dependent effects on recruitment, using field experiments. At this seasonal forest P. quinata was overrepresented by large adult trees and had very low recruitment caused by the combination of low fruit production, high seed predation and very high seedling mortality under continuous canopies mostly due to damping off pathogens. There was no evidence of negative distance or density effects on recruitment, but a clear requirement of canopy gaps for seedling survival and growth, where pathogen incidence was drastically reduced. In spite of the strong dependence on light for survival of seedlings, seeds germinated readily in the dark. At the study site, the population of P. quinata appeared to be declining, likely because recruitment depended on the rare combination of large gap formation with the presence of reproductive trees nearby. The recruitment biology of this species makes it very vulnerable to any type of logging in natural populations. Rev. Biol. Trop. 59 (2: 921-933. Epub 2011 June 01

  16. Are seed and dispersal characteristics of plants capable of predicting colonization of post-mining sites?

    Science.gov (United States)

    Horáčková, Martina; Řehounková, Klára; Prach, Karel

    2016-07-01

    Seed characteristics play an important role in the colonization and subsequent persistence of species during succession in disturbed sites and thus may contribute to being able to predict restoration success. In the present study, we investigated how various seed characteristics participated in 11 spontaneous successional series running in different mining sites (spoil heaps, extracted sand and sand-gravel pits, extracted peatlands, and stone quarries) in the Czech Republic, Central Europe. Using 1864 samples from 1- to 100-years-old successional stages, we tested whether species optimum along the succession gradient could be predicted using 10 basic species traits connected with diaspores and dispersal. Seed longevity, diaspore mass, endozoochory, and autochory appeared to be the best predictors. The results indicate that seed characteristics can predict to a certain degree spontaneous vegetation succession, i.e., passive restoration, in the mining sites. A screening of species available in the given landscape (regional and local species pools) may help to identify those species which would potentially colonize the disturbed sites. Extensive databases of species traits, nowadays available for the Central European flora, enable such screening.

  17. A new hypothesis for the importance of seed dispersal in time

    Directory of Open Access Journals (Sweden)

    Adriana Guzmán

    2011-12-01

    Full Text Available Most studies on seed dispersal in time have focused on seed dormancy and the physiological triggers for germination. However, seed dispersed by animals with low metabolic and moving rates, and long gutpassage times such as terrestrial turtles, could be considered another type of dispersal in time. This study tests the hypothesis that seeds dispersed in time may lower predation rates. We predicted that seeds deposited below parent trees after fruiting fall has finished is advantageous to minimize seed predators and should show higher survival rates. Four Amazonian plant species, Dicranostyles ampla, Oenocarpus bataua, Guatteria atabapensis and Ocotea floribunda, were tested for seed survival probabilities in two periods: during fruiting and 10-21 days after fruiting. Experiments were carried out in two biological stations located in the Colombian Amazon (Caparú and Zafire Biological Stations. Seed predation was high and mainly caused by non-vertebrates. Out of the four plant species tested, only Guatteria atabapensis supported the time escape hypothesis. For this species, seed predation by vertebrates after the fruiting period increased (from 4.1% to 9.2% while seed predation by nonvertebrates decreased (from 54.0% to 40.2%. In contrast, seed predation by vertebrates and by non-vertebrates after the fruiting period in D. ampla increased (from 7.9% to 22.8% and from 40.4% to 50.6%, respectively, suggesting predator satiation. Results suggest that for some species dispersal in time could be advantageous to avoid some type of seed predators. Escape in time could be an additional dimension in which seeds may reach adequate sites for recruitment. Thus, future studies should be address to better understand the survival advantages given by an endozoochory time-dispersal process. Rev. Biol. Trop. 59 (4: 1795-1803. Epub 2011 December 01.La mayoría de estudios sobre dispersión de semillas en el tiempo tratan sobre la dormancia de las semillas y los

  18. Intraspecific variation in seed dispersal of a Neotropical tree and its relationship to fruit and tree traits.

    Science.gov (United States)

    Augspurger, Carol K; Franson, Susan E; Cushman, Katherine C; Muller-Landau, Helene C

    2016-02-01

    The distribution of wind-dispersed seeds around a parent tree depends on diaspore and tree traits, as well as wind conditions and surrounding vegetation. This study of a neotropical canopy tree, Platypodium elegans, explored the extent to which parental variation in diaspore and tree traits explained (1) rate of diaspore descent in still air, (2) distributions of diaspores dispersed from a 40-m tower in the forest, and (3) natural diaspore distributions around the parent tree. The geometric mean rate of descent in still air among 20 parents was highly correlated with geometric mean wing loading(1/2) (r = 0.84). However, diaspore traits and rate of descent predicted less variation in dispersal distance from the tower, although descent rate(-1) consistently correlated with dispersal distance. Measured seed shadows, particularly their distribution edges, differed significantly among six parents (DBH range 62-181 cm) and were best fit by six separate anisotropic dispersal kernels and surveyed fecundities. Measured rate of descent and tree traits, combined in a mechanistic seed dispersal model, did not significantly explain variation among parents in natural seed dispersal distances, perhaps due to the limited power to detect effects with only six trees. Seedling and sapling distributions were at a greater mean distance from the parents than seed distributions; saplings were heavily concentrated at far distances. Variation among parents in the distribution tails so critical for recruitment could not be explained by measured diaspore or tree traits with this sample size, and may be determined more by wind patterns and the timing of abscission in relation to wind conditions. Studies of wind dispersal need to devote greater field efforts at recording the "rare" dispersal events that contribute to far dispersal distances, following their consequences, and in understanding the mechanisms that generate them.

  19. Ecological, historical and evolutionary determinants of modularity in weighted seed-dispersal networks

    DEFF Research Database (Denmark)

    Schleuning, Matthias; Ingmann, Lili; Strauß, Rouven

    2014-01-01

    Modularity is a recurrent and important property of bipartite ecological networks. Although well-resolved ecological networks describe interaction frequencies between species pairs, modularity of bipartite networks has been analysed only on the basis of binary presence-absence data. We employ a n...... demonstrates the dominating impact of ecological factors on the structure of seed-dispersal networks, but also underscores the relevance of evolutionary history in shaping species roles in ecological communities.......Modularity is a recurrent and important property of bipartite ecological networks. Although well-resolved ecological networks describe interaction frequencies between species pairs, modularity of bipartite networks has been analysed only on the basis of binary presence-absence data. We employ a new...... algorithm to detect modularity in weighted bipartite networks in a global analysis of avian seed-dispersal networks. We define roles of species, such as connector values, for weighted and binary networks and associate them with avian species traits and phylogeny. The weighted, but not binary, analysis...

  20. Did fleshy fruit pulp evolve as a defence against seed loss rather ...

    Indian Academy of Sciences (India)

    Wildlife Conservation Society – PNG Program, Box 277, Goroka, EHP, Papua New Guinea. (Fax, 675-732-2461; Email, amack@wcs.org). Relatively few studies have examined the evolution of the mutualism between endozoochorous plants and seed dispersers. Most seed dispersal studies are ecological and examine the ...

  1. Impacts of Seed Dispersal on Future Vegetation Structure under Changing Climates

    Science.gov (United States)

    Lee, E.; Schlosser, C. A.; Gao, X.; Prinn, R. G.

    2011-12-01

    As the impacts between land cover change, future climates and ecosystems are expected to be substantial, there are growing needs for improving the capability of simulating the global vegetation structure and landscape as realistically as possible. Current DGVMs assume ubiquitous availability of seeds and do not consider any seed dispersal mechanisms in plant migration process, which may influence the assessment of impacts to the ecosystem that rely on the vegetation structure changes (i.e., change in albedo, runoff, and terrestrial carbon sequestration capacity). This study incorporates time-varying wind-driven seed dispersal (i.e., the SEED configuration) as a dynamic constraint to the migration process of natural vegetation in the Community Land Model (CLM)-DGVM. The SEED configuration is validated using a satellite-derived tree cover dataset. Then the configuration is applied to project future vegetation structures and their implications for carbon fluxes, albedo, and hydrology under two climate mitigation scenarios (No-policy vs. 450ppm CO2 stabilization) for the 21st century. Our results show that regional changes of vegetation structure under changing climates are expected to be significant. For example, Alaska and Siberia are expected to experience substantial shifts of forestry structure, characterized by expansion of needle-leaf boreal forest and shrinkage of C3 grass Arctic. A suggested vulnerability assessment shows that vegetation structures in Alaska, Greenland, Central America, southern South America, East Africa and East Asia are susceptible to changing climates, regardless of the two climate mitigation scenarios. Regions such as Greenland, Tibet, South Asia and Northern Australia, however, may substantially alleviate their risks of rapid change in vegetation structure, given a robust greenhouse gas stabilization target. Proliferation of boreal forests in the high latitudes is expected to amplify the warming trend (i.e., a positive feedback to

  2. Pre-Dispersal Seed Predation in a Species-Rich Forest Community: Patterns and the Interplay with Determinants.

    Directory of Open Access Journals (Sweden)

    Yue Xu

    Full Text Available Pre-dispersal seed predation (PDSP is commonly observed in woody plants, and recognized as a driver of seed production variability that is critical for successful regeneration. Earlier studies on PDSP and its determinants were mostly species specific, with community-level PDSP rarely estimated; and the interactions between the temporal variability of seed production and PDSP remain elusive. In this study, the community seed rain of woody plants in a mixed evergreen-deciduous broadleaf forest was monitored for seven years. We examined predation on collected seeds and analyzed the determinants of PDSP. PDSP was recorded in 17 out of 44 woody plant species, and three-quarters of PDSP was due to insect predators. Annual seed production varied substantially at community level, reversely linked with the temporal variation of PDSP rate. The PDSP rate was biased regarding fruit types, and being significantly correlated with seed mass when using phylogenetic independent contrasts (PICs or without taking into account phylogenetic relations, especially for nuts. PDSP rate was also negatively correlated with seed density, showing a threshold-related predator satiation effect. The community-level PDSP rate was primarily determined by tree height, fruit type, and interannual variation of seed production and seed mass. Our analysis revealed a causal link between seed production and the dynamics of PDSP rate at the community level. The predator satiation effect was primarily contributed by the dominant species, whereas the rare species seemed to apply a distinct "hide-and-seek" strategy to control the risk of PDSP. The mechanistic difference of seed production between the common and rare species can shed new light on species coexistence and community assembly. Long-term monitoring of both seed rain and seed predation is required for understanding the ecological and evolutionary implications of species regeneration strategies in a species-rich forest community.

  3. Functional uniqueness of a small carnivore as seed dispersal agents: a case study of the common palm civets in the Tabin Wildlife Reserve, Sabah, Malaysia.

    Science.gov (United States)

    Nakashima, Yoshihiro; Inoue, Eiji; Inoue-Murayama, Miho; Abd Sukor, Jum Rafiah

    2010-11-01

    Many carnivorous mammals consume fruits and disperse the intact seeds to specific sites. Few studies have attempted to quantify this seed dispersal or evaluate its effectiveness, despite its potential importance and functional uniqueness. In the study reported here, we found that a frugivorous carnivore, the common palm civet (Paradoxurus hermaphroditus), generated seed shadows that are distinct from those of the sympatric frugivore, the pig-tailed macaque (Macaca nemestrina), and played a unique and important role in the regeneration of Leea aculeata (Leeaceae). We found that macaques dispersed the seeds randomly, while civets dispersed them non-randomly to sites such as the banks of small rivers, rain-flow paths, abandoned trails, and treefall gaps, which are characterized by low stem density and canopy cover. Seeds of L. aculeata that were dispersed by civets to the banks of rivers and gaps had significantly higher survival and growth rates than those dispersed to rain-flow paths or abandoned trails. Seeds dispersed by macaques or to random locations also had low survival. Although the effects of the civets on seed fate were not straightforward, compared with macaques and random dispersal, civets significantly enhanced the survival and growth of L. aculeata seeds after 1 year. These results indicate that non-random dispersal by civets is important for the persistence of L. aculeata. Civets may disperse other plant species and thus could have profound effects on forest dynamics.

  4. The physico-chemical properties of chia seed polysaccharide and its microgel dispersion rheology.

    Science.gov (United States)

    Goh, Kelvin Kim Tha; Matia-Merino, Lara; Chiang, Jie Hong; Quek, Ruisong; Soh, Stephanie Jun Bing; Lentle, Roger G

    2016-09-20

    The polysaccharide gel layer surrounding hydrated chia seeds was extracted using water and isolated by ethanol precipitation. The freeze-dried sample consisted of ∼95% non-starch polysaccharides (35% w/w neutral soluble fraction and 65% w/w negatively charged insoluble fraction). The soluble polysaccharide fraction has molar mass, root-mean square radius and intrinsic viscosity of ∼5×10(5)g/mol, 39nm and 719mL/g, respectively. The whole polysaccharide (included soluble and insoluble fractions) when dispersed in water showed presence of irregular shape, fibrous microgel particles with an average size (D4,3) of ∼700μm. Rheological measurements indicated a 'weak' viscoelastic gel and strong shear dependent properties even at low concentration (0.05% w/w). The viscosity of the dispersion was fairly resistant to variations in temperatures (20-80°C), pH (4-12), ionic strengths (0.01-0.5M NaCl) and cation types (MgCl2, CaCl2, NaCl and KCl). The swollen microgel particles dispersed in soluble polysaccharide continuous phase provided complex and potentially useful rheological properties in food systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Does animal-mediated seed dispersal facilitate the formation of Pinus armandii-Quercus aliena var. acuteserrata forests?

    Science.gov (United States)

    Yu, Fei; Wang, Dexiang; Yi, Xianfeng; Shi, Xiaoxiao; Huang, Yakun; Zhang, Hongwu; Zhang, XinPing

    2014-01-01

    The Pinus armandii and Quercus aliena var. acuteserrata mixed forest is one of the major forest types in the Qinling Mountains, China. P. armandii is considered to be a pioneer species during succession and it is usually invaded by late successional Q. aliena var. acuteserrata. However, the mechanism that underlies its invasion remains unclear. In the present study, we tracked seed dispersal of P. armandii and Q. aliena var. acuteserrata using coded plastic tags in the western, middle and eastern Qinling Mountains to elucidate the invasion process in the mixed forests. Our results indicated that the seeds of both P. armandii and Q. aliena var. acuteserrata were removed rapidly in the Qinling Mountains, and there were no differences in the seed removal rates between the two species. There were significant differences in rodent seed-eating and caching strategies between the two tree species. For P. armandii, seeds were more likely to be eaten in situ than those of Q. aliena var. acuteserrata in all plots. By contrast, the acorns of Q. aliena var. acuteserrata were less frequently eaten in situ, but more likely to be removed and cached. Q. aliena var. acuteserrata acorns had significantly longer dispersal distances than P. armandii seeds in all plots. Although P. armandii seeds were less likely to be dispersed into the Q. aliena var. acuteserrata stands, over 30% of the released acorns were transported into the P. armandii stands where they established five seedlings. Based on the coupled recruitment patterns of P. armandii and Q. aliena var. acuteserrata, we suggest that the animal-mediated seed dispersal contributes to the formation of Pinus armandii-Quercus aliena var. acuteserrata forests.

  6. Germination Ecology and Seed Dispersal of a Critically Endangered Plant: A Case Study of Pomaderris vacciniifolia (Round-Leaf Pomaderris).

    Science.gov (United States)

    Patykowski, John; Dell, Matthew; Gibson, Maria

    2016-01-01

    Change in ecosystem disturbance regimes from human land-use poses a worldwide problem for management of rare species. Two important types of disturbance influencing the persistence of species in Australian ecosystems are habitat fragmentation and fire. In this study, seed dispersal and the germination ecology of Pomaderris vacciniifolia-a critically endangered, rare endemic Australian shrub-were examined to identify likely influences of fire and fragmentation on the decline of populations. The response of seed germination to simulated effects of wildfire and canopy openings was investigated, as was the unaided dispersal capability of seeds from parent plants. A significant increase in germination rate was observed following 100°C heat treatment to seeds, while smoke and light exposure had little influence. Seed imbibition was strongly influenced by heat treatment. The findings indicate a likely positive post-fire germination response, with implications for recruitment success determined by moisture availability following fire. Unaided seed dispersal was limited, which partly explains the apparent decline of populations. Understanding disturbance requirements for threatened species, and subsequent management of landscapes for disturbance, will aid conservation of rare species throughout the world.

  7. Germination Ecology and Seed Dispersal of a Critically Endangered Plant: A Case Study of Pomaderris vacciniifolia (Round-Leaf Pomaderris.

    Directory of Open Access Journals (Sweden)

    John Patykowski

    Full Text Available Change in ecosystem disturbance regimes from human land-use poses a worldwide problem for management of rare species. Two important types of disturbance influencing the persistence of species in Australian ecosystems are habitat fragmentation and fire. In this study, seed dispersal and the germination ecology of Pomaderris vacciniifolia-a critically endangered, rare endemic Australian shrub-were examined to identify likely influences of fire and fragmentation on the decline of populations. The response of seed germination to simulated effects of wildfire and canopy openings was investigated, as was the unaided dispersal capability of seeds from parent plants. A significant increase in germination rate was observed following 100°C heat treatment to seeds, while smoke and light exposure had little influence. Seed imbibition was strongly influenced by heat treatment. The findings indicate a likely positive post-fire germination response, with implications for recruitment success determined by moisture availability following fire. Unaided seed dispersal was limited, which partly explains the apparent decline of populations. Understanding disturbance requirements for threatened species, and subsequent management of landscapes for disturbance, will aid conservation of rare species throughout the world.

  8. Germination Ecology and Seed Dispersal of a Critically Endangered Plant: A Case Study of Pomaderris vacciniifolia (Round-Leaf Pomaderris)

    Science.gov (United States)

    Dell, Matthew; Gibson, Maria

    2016-01-01

    Change in ecosystem disturbance regimes from human land-use poses a worldwide problem for management of rare species. Two important types of disturbance influencing the persistence of species in Australian ecosystems are habitat fragmentation and fire. In this study, seed dispersal and the germination ecology of Pomaderris vacciniifolia—a critically endangered, rare endemic Australian shrub—were examined to identify likely influences of fire and fragmentation on the decline of populations. The response of seed germination to simulated effects of wildfire and canopy openings was investigated, as was the unaided dispersal capability of seeds from parent plants. A significant increase in germination rate was observed following 100°C heat treatment to seeds, while smoke and light exposure had little influence. Seed imbibition was strongly influenced by heat treatment. The findings indicate a likely positive post-fire germination response, with implications for recruitment success determined by moisture availability following fire. Unaided seed dispersal was limited, which partly explains the apparent decline of populations. Understanding disturbance requirements for threatened species, and subsequent management of landscapes for disturbance, will aid conservation of rare species throughout the world. PMID:27557152

  9. Incorporating cache management behavior into seed dispersal: the effect of pericarp removal on acorn germination.

    Directory of Open Access Journals (Sweden)

    Xianfeng Yi

    Full Text Available Selecting seeds for long-term storage is a key factor for food hoarding animals. Siberian chipmunks (Tamias sibiricus remove the pericarp and scatter hoard sound acorns of Quercus mongolica over those that are insect-infested to maximize returns from caches. We have no knowledge of whether these chipmunks remove the pericarp from acorns of other species of oaks and if this behavior benefits seedling establishment. In this study, we tested whether Siberian chipmunks engage in this behavior with acorns of three other Chinese oak species, Q. variabilis, Q. aliena and Q. serrata var. brevipetiolata, and how the dispersal and germination of these acorns are affected. Our results show that when chipmunks were provided with sound and infested acorns of Quercus variabilis, Q. aliena and Q. serrata var. brevipetiolata, the two types were equally harvested and dispersed. This preference suggests that Siberian chipmunks are incapable of distinguishing between sound and insect-infested acorns. However, Siberian chipmunks removed the pericarp from acorns of these three oak species prior to dispersing and caching them. Consequently, significantly more sound acorns were scatter hoarded and more infested acorns were immediately consumed. Additionally, indoor germination experiments showed that pericarp removal by chipmunks promoted acorn germination while artificial removal showed no significant effect. Our results show that pericarp removal allows Siberian chipmunks to effectively discriminate against insect-infested acorns and may represent an adaptive behavior for cache management. Because of the germination patterns of pericarp-removed acorns, we argue that the foraging behavior of Siberian chipmunks could have potential impacts on the dispersal and germination of acorns from various oak species.

  10. Seed dispersal of a useful palm (Astrocaryum chambira Burret) in three amazonian forests with different human intervention used in ecological restoration

    International Nuclear Information System (INIS)

    Ramirez Beatriz H; Parrado Rosselli Angela; Stevenson Pablo

    2009-01-01

    The young leaves of Astrocaryum chambira are used by the indigenous people in the Amazon as raw material for handicrafts. However, few studies have been made on the natural history of this palm and on the indirect impact caused by the decrease of its dispersal agents. Considering that the loss of animal dispersal vectors due to hunting and landscape modification can affect seed dispersal processes of tropical forest plants, the goal of this study was to compare seed dispersal of A. chambira in three terra firme forests of the Colombian Amazon, with different degrees of human intervention. We censused densities of dispersal agents of A. chambira, and characterized the seed shadow. We also marked seeds to estimate dispersal distances, and established density and distance-dependent experimental stations to assess their relevance on seed dispersal. The results showed that seed removal was proportional to dispersal agent densities and forest intervention levels. Insects were the main seed predators in all sites but their effect was less pronounced in the low intervened forest site. Seed density did not show any effect on removal, while a higher probability of survival at intermediate distances from the parent palm (10 m) was found. Future studies should focus on seedling establishment, recruitment rates and the effects of human intervention on subsequent life stages of the palm.

  11. Water-dispersible hydroxyapatite nanoparticles synthesized in aqueous solution containing grape seed extract

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Ruchao, E-mail: zhouruchao520@yahoo.com.cn [School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065 (China); Si Shaoxiong, E-mail: sishaoxiong@126.com [School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065 (China); Zhang Qiyi, E-mail: qyzhang@scu.edu.cn [School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065 (China)

    2012-02-01

    A novel and effective method for the preparation of water-dispersible nano-hydroxyapatite (nHAp) particles was reported. nHAp was prepared in the presence of grape seed polyphenol (GSP) solution with different concentrations. Chemical precipitation method was adopted to produce pure nHAp and modified nHAp (nHAp-GSP) at 60 Degree-Sign C for 2 h. The chemical nature of the products was detected by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Moreover, the crystal structure and morphology of particles was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the spherical nHAp particles with a diameter of 20-50 nm could be synthesized at 60 Degree-Sign C. The zeta potential values of pure nHAp and nHAp-GSP are -0.36 mV and -26.1 mV respectively. According to the sedimentary time, the colloidal stability of nHAp-GSP in water could be improved dramatically with the increase of GSP content and the particles tended to exist as dispersive nanoparticles without aggregation. All the results indicated that GSP exhibited strong binding to nHAp and enhanced the colloidal stability of nHAp particles.

  12. Water-dispersible hydroxyapatite nanoparticles synthesized in aqueous solution containing grape seed extract

    International Nuclear Information System (INIS)

    Zhou Ruchao; Si Shaoxiong; Zhang Qiyi

    2012-01-01

    A novel and effective method for the preparation of water-dispersible nano-hydroxyapatite (nHAp) particles was reported. nHAp was prepared in the presence of grape seed polyphenol (GSP) solution with different concentrations. Chemical precipitation method was adopted to produce pure nHAp and modified nHAp (nHAp-GSP) at 60 °C for 2 h. The chemical nature of the products was detected by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Moreover, the crystal structure and morphology of particles was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the spherical nHAp particles with a diameter of 20-50 nm could be synthesized at 60 °C. The zeta potential values of pure nHAp and nHAp-GSP are -0.36 mV and -26.1 mV respectively. According to the sedimentary time, the colloidal stability of nHAp-GSP in water could be improved dramatically with the increase of GSP content and the particles tended to exist as dispersive nanoparticles without aggregation. All the results indicated that GSP exhibited strong binding to nHAp and enhanced the colloidal stability of nHAp particles.

  13. Seed dispersal turns an experimental plantation on degraded land into a novel forest in urban northern Puerto Rico

    Science.gov (United States)

    Oscar Abelleira; Elvia J. Meléndez Ackerman; Diana García Montiel; John A. Parrotta

    2015-01-01

    Planting tree species with desirable traits may catalyze forest regeneration in increasingly common degraded lands by restoring soil properties and attracting seed dispersers. We sampled forest regeneration in an experimental plantation of Albizia lebbek, an introduced N-fixing species, on a degraded pasture in northern Puerto Rico, 27 years after its establishment. We...

  14. Linking habitat suitability and seed dispersal models in order to analyse the effectiveness of hydrological fen restoration strategies

    NARCIS (Netherlands)

    Loon, A.H. van; Soomers, H.; Schot, P.P.; Bierkens, M.F.P.; Griffioen, J.; Wassen, M.J.

    2011-01-01

    The effectiveness of measures targeted at the restoration of populations of endangered species in anthropogenically dominated regions is often limited by a combination of insufficient restoration of habitat quality and dispersal failure. Therefore, the joint prediction of suitable habitat and seed

  15. Molecular approach to describing a seed-based food web: the post-dispersal granivore community of an invasive plant.

    Science.gov (United States)

    Lundgren, Jonathan G; Saska, Pavel; Honěk, Alois

    2013-06-01

    Communities of post-dispersal granivores can shape the density and dispersion of exotic plants and invasive weeds, yet plant ecologists have a limited perception of the relative trophic linkages between a seed species and members of its granivore community. Dandelion seeds marked with Rabbit IgG were disseminated into replicated plots in the recipient habitat (South Dakota) and the native range (Czech Republic). Arthropods were collected in pitfall traps, and their guts were searched for the protein marker using enzyme-linked immunosorbent assay (ELISA). Seed dishes were placed in each plot, and dandelion seed removal rates were measured. The entire experiment was repeated five times over the dandelion flowering period. Gut analysis revealed that approximately 22% of specimens tested positive for the seed marker. A more diverse granivore community had trophic linkages to seeds than has been previously realized under field conditions. This community included taxa such as isopods, millipedes, weevils, rove beetles, and caterpillars, in addition to the traditionally recognized ants, crickets, and carabid beetles. Rarefaction and Chao analysis estimated approximately 16 and 27 species in the granivore communities of the Czech Republic and South Dakota, respectively. Generalist granivore communities are diverse and polyphagous, and are clearly important as a form of biotic resistance to invasive and weedy plants. These granivore communities can be managed to limit population growth of these pests.

  16. Passive restoration following ungulate removal in a highly disturbed tropical wet forest devoid of native seed dispersers

    Science.gov (United States)

    Nafus, Melia; Savidge, Julie A.; Yackel Adams, Amy A.; Christy, Michelle T.; Reed, Robert

    2018-01-01

    Overabundant ungulate populations can alter forests. Concurrently, global declines of seed dispersers may threaten native forest structure and function. On an island largely devoid of native vertebrate seed dispersers, we monitored forest succession for 7 years following ungulate exclusion from a 5-ha area and adjacent plots with ungulates still present. We observed succession from open scrub to forest and understory cover by non-native plants declined. Two trees, native Hibiscus tiliaceus and non-native Leucaena leucocephala, accounted for most forest regeneration, with the latter dominant. Neither species is dependent on animal dispersers nor was there strong evidence that plants dependent on dispersers migrated into the 5-ha study area. Passive restoration following ungulate removal may facilitate restoration, but did not show promise for fully restoring native forest on Guam. Restoration of native forest plants in bird depopulated areas will likely require active outplanting of native seedlings, control of factors resulting in bird loss, and reintroduction of seed dispersers.

  17. Frugivory and seed dispersal patterns of the red-ruffed lemur, Varecia rubra, at a forest restoration site in Masoala National Park, Madagascar.

    Science.gov (United States)

    Martinez, Barbara T; Razafindratsima, Onja H

    2014-01-01

    Frugivorous primates can play a critical role in the regeneration of degraded habitats by dispersing seeds of their food plants. We studied the diet and seed dispersal patterns of 3 groups of habituated red-ruffed lemurs (Varecia rubra) in a rain forest restoration site in Masoala National Park, Madagascar, to assess the species' seed dispersal effectiveness. Fruits accounted for 61% of the diet, with an average foraging time of 10 min per fruit patch per day. Seeds from 75% of the consumed fruit species were recovered in the collected V. rubra feces. We traced the potential parent plants of 20 dispersed-seed species to calculate a gut passage range (63-423 min; mean = 225, n = 35). The median seed dispersal distance from the potential parent plant was 48 m (mean = 83 m, range 0-568 m, n = 194). The home ranges of 2 of the 3 groups overlapped with the regenerating forest parcels. Although 92% of fecal samples with seeds were dispersed into the undisturbed forest, V. rubra fed on the fruits of the non-native pioneer shrub Clidemia hirta, while also dispersing native and non-native seed species into the regenerating forest parcels. 2014 S. Karger AG, Basel

  18. Distribution of vascular plant species in woodland patches of Ojców National Park (southern Poland in relation to seed dispersal

    Directory of Open Access Journals (Sweden)

    Łukasz Moszkowicz

    2016-03-01

    Full Text Available Plant diaspore dispersal is a fundamental process affecting the development of forest vegetation and its natural regeneration, especially with regard to typical woodland species, which spread slowly and form short-term soil seed banks. Most of these species have poor seed dispersal mechanisms, which is the major cause of their very slow expansion. The following questions were asked: (i is there a relationship between the age of a woodland and the presence of forest vascular plant species representing different seed dispersal types; (ii how do the proportions change between species representing different seed dispersal types in relation to the age of woodland; (iii what factors determine the presence of species representing a given seed dispersal type; (iv which factors affect the presence and which ones influence the abundance of selected woodland species? A multiple regression models were developed based on data obtained from 144 woodland patches designated for the study. A probit regression analysis was performed for selected species exhibiting various seed dispersal models. Woodland plants of all seed dispersal types show a significant relationship with the age of woodland, starting from the strongest linkage: anemochores, myrmecochores, endozoochores, epizoochores, barochores, autochores. As the woodland ages, the proportion of forest myrmecochores and anemochores grows, whilst the proportion of autochores, epizoochores and endozoochores shrinks. Results obtained indicate that the direct proximity of ancient woodland has a major effect on the occurrence of more poorly dispersing plants in recent woodlands, such as myrmecochores and heavy anemochores.

  19. Environment sensing in spring-dispersed seeds of a winter annual Arabidopsis influences the regulation of dormancy to align germination potential with seasonal changes.

    Science.gov (United States)

    Footitt, Steven; Clay, Heather A; Dent, Katherine; Finch-Savage, William E

    2014-05-01

    Seed dormancy cycling plays a crucial role in the lifecycle timing of many plants. Little is known of how the seeds respond to the soil seed bank environment following dispersal in spring into the short-term seed bank before seedling emergence in autumn. Seeds of the winter annual Arabidopsis ecotype Cvi were buried in field soils in spring and recovered monthly until autumn and their molecular eco-physiological responses were recorded. DOG1 expression is initially low and then increases as dormancy increases. MFT expression is negatively correlated with germination potential. Abscisic acid (ABA) and gibberellin (GA) signalling responds rapidly following burial and adjusts to the seasonal change in soil temperature. Collectively these changes align germination potential with the optimum climate space for seedling emergence. Seeds naturally dispersed to the soil in spring enter a shallow dormancy cycle dominated by spatial sensing that adjusts germination potential to the maximum when soil environment is most favourable for germination and seedling emergence upon soil disturbance. This behaviour differs subtly from that of seeds overwintered in the soil seed bank to spread the period of potential germination in the seed population (existing seed bank and newly dispersed). As soil temperature declines in autumn, deep dormancy is re-imposed as seeds become part of the persistent seed bank. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  20. Environment sensing in spring-dispersed seeds of a winter annual Arabidopsis influences the regulation of dormancy to align germination potential with seasonal changes

    Science.gov (United States)

    Footitt, Steven; Clay, Heather A; Dent, Katherine; Finch-Savage, William E

    2014-01-01

    Seed dormancy cycling plays a crucial role in the lifecycle timing of many plants. Little is known of how the seeds respond to the soil seed bank environment following dispersal in spring into the short-term seed bank before seedling emergence in autumn.Seeds of the winter annual Arabidopsis ecotype Cvi were buried in field soils in spring and recovered monthly until autumn and their molecular eco-physiological responses were recorded.DOG1 expression is initially low and then increases as dormancy increases. MFT expression is negatively correlated with germination potential. Abscisic acid (ABA) and gibberellin (GA) signalling responds rapidly following burial and adjusts to the seasonal change in soil temperature. Collectively these changes align germination potential with the optimum climate space for seedling emergence.Seeds naturally dispersed to the soil in spring enter a shallow dormancy cycle dominated by spatial sensing that adjusts germination potential to the maximum when soil environment is most favourable for germination and seedling emergence upon soil disturbance. This behaviour differs subtly from that of seeds overwintered in the soil seed bank to spread the period of potential germination in the seed population (existing seed bank and newly dispersed). As soil temperature declines in autumn, deep dormancy is re-imposed as seeds become part of the persistent seed bank. PMID:24444091

  1. The Missing Part of Seed Dispersal Networks: Structure and Robustness of Bat-Fruit Interactions

    Science.gov (United States)

    Mello, Marco Aurelio Ribeiro; Marquitti, Flávia Maria Darcie; Guimarães, Paulo Roberto; Kalko, Elisabeth Klara Viktoria; Jordano, Pedro; de Aguiar, Marcus Aloizio Martinez

    2011-01-01

    Mutualistic networks are crucial to the maintenance of ecosystem services. Unfortunately, what we know about seed dispersal networks is based only on bird-fruit interactions. Therefore, we aimed at filling part of this gap by investigating bat-fruit networks. It is known from population studies that: (i) some bat species depend more on fruits than others, and (ii) that some specialized frugivorous bats prefer particular plant genera. We tested whether those preferences affected the structure and robustness of the whole network and the functional roles of species. Nine bat-fruit datasets from the literature were analyzed and all networks showed lower complementary specialization (H2' = 0.37±0.10, mean ± SD) and similar nestedness (NODF = 0.56±0.12) than pollination networks. All networks were modular (M = 0.32±0.07), and had on average four cohesive subgroups (modules) of tightly connected bats and plants. The composition of those modules followed the genus-genus associations observed at population level (Artibeus-Ficus, Carollia-Piper, and Sturnira-Solanum), although a few of those plant genera were dispersed also by other bats. Bat-fruit networks showed high robustness to simulated cumulative removals of both bats (R = 0.55±0.10) and plants (R = 0.68±0.09). Primary frugivores interacted with a larger proportion of the plants available and also occupied more central positions; furthermore, their extinction caused larger changes in network structure. We conclude that bat-fruit networks are highly cohesive and robust mutualistic systems, in which redundancy is high within modules, although modules are complementary to each other. Dietary specialization seems to be an important structuring factor that affects the topology, the guild structure and functional roles in bat-fruit networks. PMID:21386981

  2. Seed dormancy and germination changes of snowbed species under climate warming: the role of pre- and post-dispersal temperatures.

    Science.gov (United States)

    Bernareggi, Giulietta; Carbognani, Michele; Mondoni, Andrea; Petraglia, Alessandro

    2016-09-01

    Climate warming has major impacts on seed germination of several alpine species, hence on their regeneration capacity. Most studies have investigated the effects of warming after seed dispersal, and little is known about the effects a warmer parental environment may have on germination and dormancy of the seed progeny. Nevertheless, temperatures during seed development and maturation could alter the state of dormancy, affecting the timing of emergence and seedling survival. Here, the interplay between pre- and post-dispersal temperatures driving seed dormancy release and germination requirements of alpine plants were investigated. Three plant species inhabiting alpine snowbeds were exposed to an artificial warming treatment (i.e. +1·5 K) and to natural conditions in the field. Seeds produced were exposed to six different periods of cold stratification (0, 2, 4, 8, 12 and 20 weeks at 0 °C), followed by four incubation temperatures (5, 10, 15 and 20 °C) for germination testing. A warmer parental environment produced either no or a significant increase in germination, depending on the duration of cold stratification, incubation temperatures and their interaction. In contrast, the speed of germination was less sensitive to changes in the parental environment. Moreover, the effects of warming appeared to be linked to the level of (physiological) seed dormancy, with deeper dormant species showing major changes in response to incubation temperatures and less dormant species in response to cold stratification periods. Plants developed under warmer climates will produce seeds with changed germination responses to temperature and/or cold stratification, but the extent of these changes across species could be driven by seed dormancy traits. Transgenerational plastic adjustments of seed germination and dormancy shown here may result from increased seed viability, reduced primary and secondary dormancy state, or both, and may play a crucial role in future plant adaptation

  3. Mutualism between co-introduced species facilitates invasion and alters plant community structure

    Science.gov (United States)

    Prior, Kirsten M.; Robinson, Jennifer M.; Meadley Dunphy, Shannon A.; Frederickson, Megan E.

    2015-01-01

    Generalized mutualisms are often predicted to be resilient to changes in partner identity. Variation in mutualism-related traits between native and invasive species however, can exacerbate the spread of invasive species (‘invasional meltdown’) if invasive partners strongly interact. Here we show how invasion by a seed-dispersing ant (Myrmica rubra) promotes recruitment of a co-introduced invasive over native ant-dispersed (myrmecochorous) plants. We created experimental communities of invasive (M. rubra) or native ants (Aphaenogaster rudis) and invasive and native plants and measured seed dispersal and plant recruitment. In our mesocosms, and in laboratory and field trials, M. rubra acted as a superior seed disperser relative to the native ant. By contrast, previous studies have found that invasive ants are often poor seed dispersers compared with native ants. Despite belonging to the same behavioural guild, seed-dispersing ants were not functionally redundant. Instead, native and invasive ants had strongly divergent effects on plant communities: the invasive plant dominated in the presence of the invasive ant and the native plants dominated in the presence of the native ant. Community changes were not due to preferences for coevolved partners: variation in functional traits of linked partners drove differences. Here, we show that strongly interacting introduced mutualists can be major drivers of ecological change. PMID:25540283

  4. Redispersal of seeds by a keystone ant augments the spread of common wildflowers

    Science.gov (United States)

    Canner, Judith E.; Dunn, Robert R.; Giladi, Itamar; Gross, Kevin

    2012-04-01

    Myrmecochory (dispersal of seeds by ants) is an evolutionarily and ecologically common mutualism. Most of the research on the costs and benefits of myrmecochory in North America assumes that ant-dispersed seeds are taken to, and left in, the ant nest. Here, we use a novel seed-tracking technique to quantify secondary dispersal of seeds from the nest into the surrounding leaf litter by the keystone seed-dispersing ant, Aphaenogaster rudis. We found that A. rudis redispersed >90% of the seeds it took into its nest an average distance of 51.5 cm. A mathematical model shows redispersal increases the rate of population spread of the myrmecochores Hexastylis arifolia and Asarum canadense by 22.5%, and increases the expected cumulative dispersal distance away from the parent plant by 24%. Our results suggest myrmecochory benefits plants in eastern North American forests by increasing the distance between the seed and parent plant and reducing competition among siblings.

  5. Post-dispersal seed predation of woody forest species limits recolonization of forest plantations on ex-arable land

    DEFF Research Database (Denmark)

    Bruun, Hans Henrik; Valtinat, Karin; Kollmann, Johannes

    2010-01-01

    -generation forest plantations on ex-arable land and re-planted clear-cuts on continuously forested land. There was no recruitment following the experimental sowing of six commonwoody species (Alnus glutinosa, Betula pendula, Frangula alnus, Sambucus nigra, Sorbus aucuparia and Sorbus intermedia). Thus......, the colonization of forest plantations by native shrubs and trees appears to be habitat-limited; the only exception being Rhamnus catharticus, for which poor dispersal ability may be more important. Post-dispersal seed predation of forest shrubs and trees was marked, especially in relatively small and isolated...

  6. Germination Ecology and Seed Dispersal of a Critically Endangered Plant: A Case Study of Pomaderris vacciniifolia (Round-Leaf Pomaderris)

    OpenAIRE

    Patykowski, John; Dell, Matthew; Gibson, Maria

    2016-01-01

    Change in ecosystem disturbance regimes from human land-use poses a worldwide problem for management of rare species. Two important types of disturbance influencing the persistence of species in Australian ecosystems are habitat fragmentation and fire. In this study, seed dispersal and the germination ecology of Pomaderris vacciniifolia-a critically endangered, rare endemic Australian shrub-were examined to identify likely influences of fire and fragmentation on the decline of populations. Th...

  7. Endozoochorous dispersal of aquatic plants: does seed gut passage affect plant performance?

    NARCIS (Netherlands)

    Figuerola, J.; Santamaría, L.; Green, A.J.; Luque, I.; Alvarez, R.; Charalambidou, I.

    2005-01-01

    The ingestion of seeds by vertebrates can affect the germinability and/or germination rate of seeds. It is, however, unclear if an earlier germination as a result of ingestion affects later plant performance. For sago pondweed, Potamogeton pectinatus, the effects of seed ingestion by ducks on both

  8. The influence of white pine blister rust on seed dispersal in whitebark pine

    Science.gov (United States)

    Shawn T. McKinney; Diana F. Tomback

    2007-01-01

    We tested the hypotheses that white pine blister rust (Cronartium ribicola J.C. Fisch.) damage in whitebark pine (Pinus albicaulis Engelm.) stands leads to reduced (1) seed cone density, (2) predispersal seed survival, and (3) likelihood of Clark's Nutcracker (Nucifraga columbiana (Wilson, 1811)) seed...

  9. Strong dependence of a pioneer shrub on seed dispersal services provided by an endemic endangered lizard in a Mediterranean island ecosystem.

    Science.gov (United States)

    Neghme, Constanza; Santamaría, Luís; Calviño-Cancela, María

    2017-01-01

    The accelerating rate of vertebrate extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes such as animal seed dispersal. The study of highly specialized mutualistic interactions is crucial to predict the consequences of population declines and extinctions. Islands offer unique opportunities to study highly specialized interactions, as they often have naturally depauperated faunas and are experiencing high rates of human-driven extinctions. In this study, we assess the effect of seed dispersal on seedling recruitment of Ephedra fragilis (Ephedraceae) on a Mediterranean island ecosystem. We used field data and stochastic simulation modeling to estimate seed fate and recruitment patterns of this pioneer shrub typical of arid and semiarid areas, and to estimate the dependence of recruitment on the lizard Podarcis lilfordi (Lacertidae), its only known seed disperser. Ephedra fragilis recruitment highly depended on lizards: lizards produced 3.8 times more newly-emerged seedlings than non-dispersed seeds and no seedlings from undispersed seeds survived the study period. Seed dispersal by lizards was mostly to open sites, which was key for the increased success observed, while undispersed seeds, falling under mother plants, suffered higher predation and lower seedling emergence and survival. The ability of this pioneer shrub to get established in open ground is crucial for vegetation colonization and restoration, especially on degraded lands affected by desertification, where they act as nurse plants for other species. Lizards are key in this process, which has important consequences for community structure and ecosystem functioning.

  10. Myrmecochory and short-term seed fate in Rhamnus alaternus: Ant species and seed characteristics

    Science.gov (United States)

    Bas, J. M.; Oliveras, J.; Gómez, C.

    2009-05-01

    Benefits conferred on plants in ant-mediated seed dispersal mutualisms (myrmecochory) depend on the fate of transported seeds. We studied the effects of elaiosome presence, seed size and seed treatment (with and without passage through a bird's digestive tract) on short-term seed fate in Rhamnus alaternus. In our study, we define short-term seed, or initial, seed fate, as the location where ants release the seeds after ant contact with it. The elaiosomes had the most influence on short-term fate, i.e. whether or not seeds were transported to the nest. The workers usually transported big seeds more often than small ones, but small ants did not transport large seeds. Effect of seed size on transport depended on the ant species and on the treatment of the seed (manual extraction simulating a direct fall from the parent plant vs. bird deposition corresponding to preliminary primary dispersal). Probability of removal of elaiosome-bearing seeds to the nest by Aphaenogaster senilis increased with increasing seed weight.

  11. Influence of habitat complexity and landscape configuration on pollination and seed-dispersal interactions of wild cherry trees.

    Science.gov (United States)

    Breitbach, Nils; Tillmann, Svenja; Schleuning, Matthias; Grünewald, Claudia; Laube, Irina; Steffan-Dewenter, Ingolf; Böhning-Gaese, Katrin

    2012-02-01

    Land-use intensification is a major cause for the decline in species diversity in human-modified landscapes. The loss of functionally important species can reduce a variety of ecosystem functions, such as pollination and seed dispersal, but the intricate relationships between land-use intensity, biodiversity and ecosystem functioning are still contentious. Along a gradient from forest to intensively used farmland, we quantified bee species richness, visitation rates of bees and pollination success of wild cherry trees (Prunus avium). We analysed the effects of structural habitat diversity at a local scale and of the proportion of suitable habitat around each tree at a landscape scale. We compared these findings with those from previous studies of seed-dispersing birds and mammals in the same model system and along the same land-use gradient. Bee species richness and visitation rates were found to be highest in structurally simple habitats, whereas bird species richness--but not their visitation rates--were highest in structurally complex habitats. Mammal visitation rates were only influenced at the landscape scale. These results show that different functional groups of animals respond idiosyncratically to gradients in habitat and landscape structure. Despite strong effects on bees and birds, pollination success and bird seed removal did not differ along the land-use gradient at both spatial scales. These results suggest that mobile organisms, such as bees and birds, move over long distances in intensively used landscapes and thereby buffer pollination and seed-dispersal interactions. We conclude that measures of species richness and interaction frequencies are not sufficient on their own to understand the ultimate consequences of land-use intensification on ecosystem functioning.

  12. Post-abscission, pre-dispersal seeds of Digitalis purpurea remain in a developmental state that is not terminated by desiccation ex planta.

    Science.gov (United States)

    Butler, L H; Hay, F R; Ellis, R H; Smith, R D

    2009-03-01

    Seed quality may be compromised if seeds are harvested before natural dispersal (shedding). It has been shown previously that slow or delayed drying can increase potential quality compared with immediate rapid drying. This study set out to investigate whether or not there is a critical moisture content, below which drying terminates maturation events for seeds harvested after mass maturity but before dispersal. Seeds of foxglove (Digitalis purpurea) in the post-abscission pre-dispersal phase were held at between 15 and 95 % RH for 4 or 8 d, with or without re-hydration to 95 % RH for a further 4 d, before drying to equilibrium at 15 % RH. In addition, dry seeds were primed for 48 h at -1 MPa. Subsequent seed longevity was assessed at 60 % RH and 45 degrees C. Rate of germination and longevity were improved by holding seeds at a wide range of humidities after harvest. Longevity was further improved by re-hydration at 95 % RH. Priming improved the longevity of the seeds dried immediately after harvest, but not of those first held at 95 % RH for 8 d prior to drying. Maturation continued ex planta in these post-abscission, pre-dispersal seeds of D. purpurea dried at 15-80 % RH at a rate correlated positively with RH (cf. ageing of mature seeds). Subsequent re-hydration at 95 % RH enabled a further improvement in quality. Priming seeds initially stored air-dry for 3 months also allowed maturation events to resume. However, once individual seeds within the population had reached maximum longevity, priming had a negative impact on their subsequent survival.

  13. Spatial patterns of water-dispersed seed deposition along stream riparian gradients

    NARCIS (Netherlands)

    Fraaije, Rob G.A.; Moinier, Sophie; Van Gogh, Iris; Timmers, Robert; Van Deelen, Joost J.; Verhoeven, Jos; Soons, Merel B.

    2017-01-01

    Riparian ecosystems along streams naturally harbour a high plant diversity with many increasingly endangered species. In our current heavily modified and fragmented catchments, many of these species are sensitive to dispersal limitation. Better understanding of riparian plant dispersal pathways is

  14. Fine-scale spatial genetic structure in predominantly selfing plants with limited seed dispersal: A rule or exception?

    Directory of Open Access Journals (Sweden)

    Sergei Volis

    2016-04-01

    Full Text Available Gene flow at a fine scale is still poorly understood despite its recognized importance for plant population demographic and genetic processes. We tested the hypothesis that intensity of gene flow will be lower and strength of spatial genetic structure (SGS will be higher in more peripheral populations because of lower population density. The study was performed on the predominantly selfing Avena sterilis and included: (1 direct measurement of dispersal in a controlled environment; and (2 analyses of SGS in three natural populations, sampled in linear transects at fixed increasing inter-plant distances. We found that in A. sterilis major seed dispersal is by gravity in close (less than 2 m vicinity of the mother plant, with a minor additional effect of wind. Analysis of SGS with six nuclear SSRs revealed a significant autocorrelation for the distance class of 1 m only in the most peripheral desert population, while in the two core populations with Mediterranean conditions, no genetic structure was found. Our results support the hypothesis that intensity of SGS increases from the species core to periphery as a result of decreased within-population gene flow related to low plant density. Our findings also show that predominant self-pollination and highly localized seed dispersal lead to SGS at a very fine scale, but only if plant density is not too high.

  15. Cecropia as a food resource for bats in French Guiana and the significance of fruit structure in seed dispersal and longevity.

    Science.gov (United States)

    Lobova, Tatyana A; Mori, Scott A; Blanchard, Frédéric; Peckham, Heather; Charles-Dominique, Pierre

    2003-03-01

    Cecropia (Cecropiaceae) is a Neotropical genus of pioneer plants. A review of bat/plant dispersal interactions revealed that 15 species of Cecropia are consumed by 32 species of bats. In French Guiana, bats were captured in primary and secondary forests, yielding 936 fecal samples with diaspores, among which 162 contained fruits of C. obtusa, C. palmata, and C. sciadophylla. A comparative morphological and anatomical study of fruits and seeds taken directly from herbarium specimens, bat feces, and an experimental soil seed bank was made. Contrary to previous reports, the dispersal unit of Cecropia is the fruit not the seed. Bats consume the infructescence, digest pulp derived from the enlarged, fleshy perianth, and defecate the fruits. The mucilaginous pericarp of Cecropia is described. The external mucilage production of Cecropia may facilitate endozoochory. The exocarp and part of the mesocarp may be lost after passage through the digestive tract of bats, but fruits buried for a year in the soil seed bank remain structurally unchanged. Fruit characters were found to be useful for identifying species of bat-dispersed Cecropia. Bat dispersal is not necessary for seed germination but it increases seed survival and subsequent germination. Fruit structure plays a significant role in seed longevity.

  16. Surface properties and physiology of Ulmus laevis and U. minor samaras: implications for seed development and dispersal.

    Science.gov (United States)

    Guzmán-Delgado, Paula; Fernández, Victoria; Venturas, Martin; Rodríguez-Calcerrada, Jesús; Gil, Luis

    2017-06-01

    Plant surface properties influence solid-liquid interactions and matter exchange between the organs and their surrounding environment. In the case of fruits, surface processes may be of relevance for seed production and dispersal. To gain insight into the relationship between surface structure, chemical composition and function of aerial reproductive organs, we performed diverse experiments with the dry, winged fruits, or samaras, of Ulmus laevis Pall. and Ulmus minor Mill. both at the time of full maturity (green samaras) and of samara dispersal (dry samaras). Samaras of both elm species showed positive photosynthetic rates and absorbed water through their epidermal surfaces. The surface wettability, free energy, polarity and solubility parameter were lower in U. laevis than in U. minor and decreased for dry samaras in both species. Ulmus laevis samaras had a high degree of surface nano-roughness mainly conferred by cell wall folds containing pectins that substantially increased after hydration. The samaras in this species also had a thicker cuticle that could be isolated by enzymatic digestion, whereas that of U. minor samaras had higher amounts of soluble lipids. Dry samaras of U. laevis had higher floatability and lower air sustentation than those of U. minor. We concluded that samaras contribute to seed development by participating in carbon and water exchange. This may be especially important for U. minor, whose samaras develop before leaf emergence. The trichomes present along U. laevis samara margin may enhance water absorption and samara floatability even in turbulent waters. In general, U. minor samaras show traits that are consistent with a more drought tolerant character than U. laevis samaras, in line with the resources available both at the tree and ecosystem level for these species. Samara features may additionally reflect different adaptive strategies for seed dispersal and niche differentiation between species, by favoring hydrochory for U. laevis

  17. CEPF Western Ghats Special Series: Frugivory and seed dispersal by the Asian Elephant Elephas maximus in the tropical forests of Nilgiri Biosphere Reserve, southern India

    Directory of Open Access Journals (Sweden)

    N. Baskaran

    2014-10-01

    Full Text Available Seed dispersal plays a potential role in plant species demographic processes. Elephants are important seed-dispersing agents. We studied frugivory and seed dispersal by Asian Elephants in the tropical deciduous and thorn forests of the Nilgiri Biosphere Reserve, southern India. We determined fruit consumption based on the presence of seeds and fruit remnants in elephant dung piles. In total, we identified seeds of eight plant species belonging to seven families in 16% out of 455 dung piles examined between 1991 and 2004. Coinciding with a peak fruiting season in the study area, seeds and other fruit parts appeared in the dung piles significantly more frequently during the dry season than in the wet seasons (southwest and northeast monsoons. Owing to differences in fruit species abundance in different habitats, there was more evidence of fruit consumption in the dry thorn than in the dry and moist deciduous forests. This corresponds with insufficient grass availability in thorn forests during the dry season and an increase in browse consumption as a supplementary diet. Seeds of Tamarindus indica and Acacia intsia were found in elephant dung more frequently than other species. Seed and fruit remnants were found in almost an equal number of dung piles of both bulls and herds.

  18. Potential role of frugivorous birds (Passeriformes on seed dispersal of six plant species in a restinga habitat, southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Verônica Souza da Mota Gomes

    2008-03-01

    Full Text Available Restingas are considered stressful habitats associated with the Brazilian Atlantic forest, and their ecological interactions are poorly known. The goal of the present study was to determine the potential role of frugivorous birds as seed dispersers in a restinga habitat. Data were collected in Parque Nacional da Restinga de Jurubatiba, southeastern Brazil, where the main physiognomy (Open Clusia Formation is characterized by the presence of patches of vegetation covering 20 to 48 % of the sandy soil and reaching a height of 5 m. Birds were captured with mist nets (12 x 2.5 m; 36 mm mesh; 1 680 net-hrs and had their fecal and regurgitate samples inspected for seeds. Six plant species found in these bird samples were studied. The germination of seeds obtained from plants was compared to those from the birds. Both groups of seeds were set on Petri dishes at room temperature and washed when infected with fungi. In general, there was no effect on germination rate, and the effect on germination speed was negative. Germination of seeds from Pilosocereus arrabidae treated by the birds seemed to be influenced by storage of defecated seeds, while few Miconia cinnamomifolia seeds both from plants and from birds germinated. Ocotea notata presented a great variation in time to the onset of germination, perhaps an advantage against dissecation. Aechmea nudicaulis, Clusia hilariana and Erythroxylum subsessile probably take advantage of the arrival to favorable microhabitats, not by the gut effect on the seeds. All plant species studied are numerically important for the community and some of them are main actors in the succession of vegetation patches. Among the birds, Mimus gilvus is an important resident species, endemic to restingas in Brazil, while Turdus amaurochalinus is a visitor and may be important for plants that fructify during its passage by the study site. Although the effect of pulp removal was only tested for one species (Achmea nudicaulis in the

  19. Small seed size increases the potential for dispersal of wetland plants by ducks

    NARCIS (Netherlands)

    Soons, M.B.; van der Vlugt, C.; van Lith, B.; Heil, G.W.; Klaassen, M.R.J.

    2008-01-01

    1. Long-distance dispersal (LDD) is important in plants of dynamic and ephemeral habitats. For plants of dynamic wetland habitats, waterfowl are generally considered to be important LDD vectors. However, in comparison to the internal (endozoochorous) dispersal of terrestrial plants by birds,

  20. Do Hybrid Trees Inherit Invasive Characteristics? Fruits of Corymbia torelliana X C. citriodora Hybrids and Potential for Seed Dispersal by Bees.

    Science.gov (United States)

    Wallace, Helen Margaret; Leonhardt, Sara Diana

    2015-01-01

    Tree invasions have substantial impacts on biodiversity and ecosystem functioning, and trees that are dispersed by animals are more likely to become invasive. In addition, hybridisation between plants is well documented as a source of new weeds, as hybrids gain new characteristics that allow them to become invasive. Corymbia torelliana is an invasive tree with an unusual animal dispersal mechanism: seed dispersal by stingless bees, that hybridizes readily with other species. We examined hybrids between C. torelliana and C. citriodora subsp. citriodora to determine whether hybrids have inherited the seed dispersal characteristics of C. torelliana that allow bee dispersal. Some hybrid fruits displayed the characteristic hollowness, resin production and resin chemistry associated with seed dispersal by bees. However, we did not observe bees foraging on any hybrid fruits until they had been damaged. We conclude that C. torelliana and C. citriodora subsp. citriodora hybrids can inherit some fruit characters that are associated with dispersal by bees, but we did not find a hybrid with the complete set of characters that would enable bee dispersal. However, around 20,000 hybrids have been planted in Australia, and ongoing monitoring is necessary to identify any hybrids that may become invasive.

  1. Complementary seed dispersal by three avian frugivores in a fragmented Afromontane forest

    NARCIS (Netherlands)

    Lehouck, V.; Spanhove, T.; Demeter, S.; Groot, N.E.; Lens, L.

    2009-01-01

    Questions To what extent does species-specific variation in gut passage time (GPT), habitat use and mobility of three key avian frugivores synergistically affect the distribution of Xymalos monospora seeds within and among isolated forest fragments? Location Three fragments of a severely fragmented

  2. Seed, dispersal, microsite, habitat and recruitment limitation - identification of terms and concepts in studies of limitations

    Czech Academy of Sciences Publication Activity Database

    Münzbergová, Zuzana; Herben, Tomáš

    2005-01-01

    Roč. 145, - (2005), s. 1-8 ISSN 0029-8549 R&D Projects: GA ČR(CZ) GD206/03/H137 Institutional research plan: CEZ:AV0Z60050516 Keywords : limitation * seeds * sowing Subject RIV: EF - Botanics Impact factor: 3.032, year: 2005

  3. Seed dispersal in limber and southwestern white pine: Comparing core and peripheral populations

    Science.gov (United States)

    Diana F. Tomback; Sheridan Samano; Elizabeth L. Pruett; Anna W. Schoettle

    2011-01-01

    According to the geographic mosaic theory of coevolution (Thompson 2005), the potential for coevolutionary relationships between interacting species varies with the presence of other species within a community. This implies that the strength of coevolution between two species may vary geographically. In this study, we ask whether there is a shift in vertebrate seed...

  4. Effects of seed dispersal by animals on the regeneration of Bursera graveolens (Burseraceae) on Santa Fe Island, Galápagos.

    Science.gov (United States)

    Clark, Deborah A; Clark, David B

    1981-05-01

    The importance of animals as seed dispersers for Bursera graveolens (Burseraceae) was assessed by analysis of juvenileadult interplant distances on Santa Fe Island, Galápagos. The Santa Fe Bursera population consists of two non-overlapping classes old, large adults, and juveniles recruited since the exermination of feral goats in 1971. Juveniles occurred on a variety of substrate types, as well as under and away from woody vegetation. Most juveniles arise from seeds dispersed by animals; 86% of the juveniles were ≧3 m away from the crown of the nearest adult, and half were ≧7 m away. Although all juveniles occurred within 35 m of an adult Bursera, seed dispersal by animals is an important factor in the regeneration of B. graveolens on Santa Fe.

  5. Conflicting selection in the course of adaptive diversification: the interplay between mutualism and intraspecific competition.

    Science.gov (United States)

    Raimundo, Rafael L G; Gibert, Jean P; Hembry, David H; Guimarães, Paulo R

    2014-03-01

    Adaptive speciation can occur when a population undergoes assortative mating and disruptive selection caused by frequency-dependent intraspecific competition. However, other interactions, such as mutualisms based on trait matching, may generate conflicting selective pressures that constrain species diversification. We used individual-based simulations to explore how different types of mutualism affect adaptive diversification. A magic trait was assumed to simultaneously mediate mate choice, intraspecific competition, and mutualisms. In scenarios of intimate, specialized mutualisms, individuals interact with one or few individual mutualistic partners, and diversification is constrained only if the mutualism is obligate. In other scenarios, increasing numbers of different partners per individual limit diversification by generating stabilizing selection. Stabilizing selection emerges from the greater likelihood of trait mismatches for rare, extreme phenotypes than for common intermediate phenotypes. Constraints on diversification imposed by increased numbers of partners decrease if the trait matching degree has smaller positive effects on fitness. These results hold after the relaxation of various assumptions. When trait matching matters, mutualism-generated stabilizing selection would thus often constrain diversification in obligate mutualisms, such as ant-myrmecophyte associations, and in low-intimacy mutualisms, including plant-seed disperser systems. Hence, different processes, such as trait convergence favoring the incorporation of nonrelated species, are needed to explain the higher richness of low-intimacy assemblages--shown here to be up to 1 order of magnitude richer than high-intimacy systems.

  6. Migration by seed dispersal of ACCase-inhibitor-resistant Avena fatua in north-western Mexico.

    Science.gov (United States)

    Tafoya-Razo, J Antonio; Núñez-Farfán, Juan; Torres-García, Jesús R

    2017-01-01

    Biotypes of Avena fatua resistant to ACCase-inhibiting herbicides have been reported in the States of Baja California (BC) and Sonora (SON), Mexico. We hypothesised that resistant biotypes present in SON (Valle de Hermosillo and Valle del Yaqui) are derived from a resistant population from BC (Valle de Mexicali) via gene flow through the transport and exchange of contaminated wheat seed. This study aimed to determine (1) the resistance of A. fatua to ACCase-inhibiting herbicides in populations from BC and SON, (2) the mutation at the site of action and (3) the genetic structure and gene flow among populations. DNA sequencing showed that all biotypes shared the same mutation (Leu × Ile at codon 1781). Microsatellites showed evidence of a genetic bottleneck in SON, and spatial analysis of molecular variance grouped one biotype from the Valle de Mexicali with two biotypes from the Valle de Hermosillo. Migration analysis suggested gene flow from the Valle de Mexicali to the Valle de Hermosillo, but not to the Valle del Yaqui. The presence of resistant biotypes of A. fatua in the Valle de Hermosillo, SON, are likely derived from seeds from BC, possibly through the transport of contaminated wheat seeds. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  7. Seed dispersal in páramo plants : epizoochorous and hydrochorous taxa

    NARCIS (Netherlands)

    Melcher, I.; Bouman, F.; Cleef, A.M.

    2000-01-01

    On the basis of a recent checklist of plant diversity in páramos, diaspores collected from herbaria were studied for adaptations to dispersal on animals and by water. This study shows that the páramo flora has a relatively high percentage of genera with morphological adaptations to epizoochorous and

  8. Phylogeography and seed dispersal in islands: the case of Rumex bucephalophorus subsp. canariensis (Polygonaceae).

    Science.gov (United States)

    Talavera, María; Navarro-Sampedro, Laura; Ortiz, Pedro L; Arista, Montserrat

    2013-02-01

    Rumex bucephalophorus subsp. canariensis is an endemic taxon to Macaronesia with diaspore polymorphism. The origin and colonizing route of this taxon in Macaronesia was studied using molecular data and information on diaspore types. Amplified fragment length polymorphism (AFLP) was used in 260 plants from 22 populations of R. bucephalophorus subsp. canariensis, four from the Madeiran archipelago and 18 from the Canary archipelago. Diaspore production was analysed in 9-50 plants from each population used for AFLP analysis. One hundred and one plants from the Madeiran archipelago and 375 plants from the Canary Islands were studied. For each plant the type of diaspore produced was recorded. Overall populations had low genetic diversity but they showed a geographical pattern of genetic diversity that was higher in the older eastern islands than in the younger western ones. Two types of dispersible diaspores were found: in the eastern Canary islands (Lanzarote, Fuerteventura and Gran Canaria), plants produced exclusively long-dispersible diaspores, whereas in the western Canary islands (Tenerife, La Gomera, El Hierro) and the Madeiran archipelago plants produced exclusively short-dispersible diaspores. Genetically, the studied populations fell into four main island groups: Lanzarote-Fuerteventura, Gran Canaria, Tenerife-El Hierro and La Gomera-Madeira archipelago. A Moroccan origin of R. bucephalophorus subsp. canariensis is hypothesized with a colonization route from the eastern to the western islands. In addition, at least one gene flow event from La Gomera to the Madeiran archipelago has taken place. During the colonization process the type of dispersible diaspore changed so that dispersability decreased in populations of the westernmost islands.

  9. Self-organization, scaling and collapse in a coupled automaton model of foragers and vegetation resources with seed dispersal

    International Nuclear Information System (INIS)

    Boyer, D; Lopez-Corona, O

    2009-01-01

    We introduce a model of travelling agents (e.g., frugivorous animals) who feed on randomly located vegetation patches and disperse their seeds, thus modifying the spatial distribution of the resources in the long term. It is assumed that the survival probability of a seed increases with the distance to its parent patch and decreases with the size of the colonized patch. In turn, the foraging agents use a deterministic strategy with memory that makes them visit the largest possible patches accessible within minimal travelling distances. The combination of these interactions produce complex spatio-temporal patterns. If the patches have a small initial size, the vegetation total mass (biomass) increases with time and reaches a maximum corresponding to a self-organized critical state with power-law-distributed patch sizes and Levy-like movement patterns for the foragers. However, this state collapses as the biomass sharply decreases to reach a noisy stationary regime characterized by corrections to scaling. In systems with low plant competition, the efficiency of the foraging rules leads to the formation of heterogeneous vegetation patterns with 1/f α frequency spectra, and contributes, rather counter-intuitively, to lower the biomass levels.

  10. Effects of male fecundity, interindividual distance and anisotropic pollen dispersal on mating success in a Scots pine (Pinus sylvestris) seed orchard.

    Science.gov (United States)

    Torimaru, T; Wennström, U; Lindgren, D; Wang, X-R

    2012-03-01

    Quantifying the effect of pollen dispersal and flowering traits on mating success is essential for understanding evolutionary responses to changing environments and establishing strategies for forest tree breeding. This study examined, quantitatively, the effects of male fecundity, interindividual distance and anisotropic pollen dispersal on the mating success of Scots pine (Pinus sylvestris), utilizing a well-mapped Scots pine seed orchard. Paternity analysis of 1021 seeds sampled from 87 trees representing 28 clones showed that 53% of the seeds had at least one potential pollen parent within the orchard. Pronounced variation in paternal contribution was observed among clones. Variations in pollen production explained up to 78% of the variation in mating success, which was 11.2 times greater for clones producing the largest amount of pollen than for clones producing the least pollen. Mating success also varied with intertree distance and direction, which explained up to 28% of the variance. Fertilization between neighboring trees 2.3 m apart was 2.4 times more frequent than between trees 4.6 m apart, and up to 12.4 times higher for trees downwind of the presumed prevailing wind direction than for upwind trees. The effective number of pollen donors recorded in the seed orchard (12.2) was smaller than the theoretical expectation (19.7). Based on the empirical observations, a mating model that best describes the gene dispersal pattern in clonal seed orchards was constructed.

  11. The impact of anthropogenic food supply on fruit consumption by dusky-legged guan (Penelope obscura Temminck, 1815): potential effects on seed dispersal in an Atlantic forest area.

    Science.gov (United States)

    Vasconcellos-Neto, J; Ramos, R R; Pinto, L P

    2015-11-01

    Frugivorous birds are important seed dispersers and influence the recruitment of many plant species in the rainforest. The efficiency of this dispersal generally depends on environment quality, bird species, richness and diversity of resources, and low levels of anthropogenic disturbance. In this study, we compared the sighting number of dusky-legged guans (Penelope obscura) by km and their movement in two areas of Serra do Japi, one around the administrative base (Base) where birds received anthropogenic food and a pristine area (DAE) with no anthropogenic resource. We also compared the richness of native seeds in feces of birds living in these two areas. Although the abundance of P. obscura was higher in the Base, these individuals moved less, dispersed 80% fewer species of plants and consumed 30% fewer seeds than individuals from DAE. The rarefaction indicated a low richness in the frugivorous diet of birds from the Base when compared to the populations from DAE. We conclude that human food supply can interfere in the behavior of these birds and in the richness of native seeds dispersed.

  12. seeds

    African Journals Online (AJOL)

    Owner

    peptidohydrolase (8.0%) from mung bean seedlings. (Baumgartner and Chrispeels, 1977), EP-HG (4.5%) from horse gram seedlings ( Rajeswari, 1997), acidic protease (15%) from germinating winged-bean seeds. (Usha and Singh, 1996) and EP-1 (1.6%) from barley seedlings and GA3-induced cysteine protease (3.38%).

  13. Conjugated polymer shells on colloidal templates by seeded Suzuki–Miyaura dispersion polymerization.

    Science.gov (United States)

    ten Hove, Jan Bart; Appel, Jeroen; van den Broek, Johanna M; Kuehne, Alexander J C; Sprakel, Joris

    2014-03-12

    The self-assembly of colloidal conjugated polymers presents a versatile and powerful oute towards new functional optoelectronic materials and devices. However, this strategy relies on the existence of chemical protocols to prepare highly monodisperse colloids of conjugated polymers in high yields. Here, a recently developed Suzuki–Miyaura dispersion polymerization method is adopted to synthesize core–shell particles, in which a conjugated polymer shell is grown onto non-conjugated organic and inorganic colloidal templates. By chemically anchoring aryl halide groups at the particle surface, a conjugated polymer shell can be attached to a wide variety of organic and inorganic microparticles. In this way, both spherical and non-spherical hybrid conjugated polymer particles are prepared, and it is shown that the method can be applied to a variety of conjugated polymers. This new method offers independent control of the size, shape and photophysical properties of these novel conjugated polymer particles.

  14. On-the-fly green generation and dispersion of AgI nanoparticles for cloud seeding nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiuli; Zhou, Wenbo; Wang, Xizheng; Wu, Tao; Delisio, Jeffery B.; Zachariah, Michael R., E-mail: mrz@umd.edu [University of Maryland, Department of Chemical and Biomolecular Engineering (United States)

    2016-07-15

    This study reports on an on-the-fly green synthesis/dispersion of silver iodide (AgI) nanoparticles from the combustion of AgIO{sub 3}/carbon black (CB)/nitrocellulose (NC) composites, which could be used as a candidate for a cloud-seeding pyrotechnic. Films were formed by direct electrospray deposition of a mixture of synthesized silver iodate with CB and NC. The decomposition pathways of AgIO{sub 3}/CB and AgIO{sub 3}/CB/NC were evaluated by temperature jump time of flight mass spectrometry (T-jump TOFMS) and XRD, showing that AgI particles and CO{sub 2} are released from the reaction between AgIO{sub 3} and CB without other toxic residuals. The flame propagation velocity of AgIO{sub 3}/CB/NC films increases with the increasing of particle mass loading of AgIO{sub 3} and CB and peaks at 40 wt%, which is much higher than that of an AgI/AP/NC film. The mean diameter of the resultant AgI nanoparticles is from 51 to 97 nm. The mass loading of AgIO{sub 3} and CB was found to play a major role in size control of the AgI nanoparticles.

  15. Dispersal phenology of hydrochorous plants in relation to discharge, seed release time and buoyancy of seeds: the flood pulse concept supported

    NARCIS (Netherlands)

    Boedeltje, G.; Bakker, J.P.; Brinke, A. Ten; Groenendael, J.M. van; Soesbergen, M.

    2004-01-01

    1 Restored floodplains and backwaters lacking a viable propagule bank, may need flood pulses to facilitate inward dispersal of diaspores. Temporal patterns of hydrochorous plant dispersal are, however, not well known. 2 Diversity and abundance of diaspores dispersed in a water body over 12 months

  16. Dispersal phenology of hydrochorous plants in relation to discharge, seed release time and buoyancy of seeds : the flood pulse concept supported

    NARCIS (Netherlands)

    Boedeltje, G; Bakker, JP; Ten Brinke, A; Van Groenendael, JM; Soesbergen, M

    2004-01-01

    1 Restored floodplains and backwaters lacking a viable propagule bank, may need flood pulses to facilitate inward dispersal of diaspores. Temporal patterns of hydrochorous plant dispersal are, however, not well known. 2 Diversity and abundance of diaspores dispersed in a water body over 12 months

  17. High-resolution GPS tracking reveals habitat selection and the potential for long-distance seed dispersal by Madagascan flying foxes Pteropus rufus

    Directory of Open Access Journals (Sweden)

    Ryszard Oleksy

    2015-01-01

    Full Text Available Long-distance seed dispersal can be important for the regeneration of forested habitats, especially in regions where deforestation has been severe. Old World fruit bats (Pteropodidae have considerable potential for long-distance seed dispersal. We studied the movement patterns and feeding behaviour of the endemic Madagascan flying fox Pteropus rufus, in Berenty Reserve, southeast Madagascar. Between July and September 2012 (the dry season nine males and six females were tagged with customised GPS loggers which recorded fixes every 2.5 min between 18.00 and 06.00 h. The combined home range of all of the tagged bats during 86 nights exceeded 58,000 ha. Females had larger home ranges and core foraging areas and foraged over longer distances (average 28.1 km; median 26.7 km than males (average 15.4 km; median 9.5 km. Because the study was conducted during the gestation period, the increased energy requirements of females may explain their greater mean foraging area. Compositional analysis revealed that bats show strong preferences for overgrown sisal (Agave sisalana plantations (a mix of shrub, trees and sisal plants and remnant riverside forest patches. Sisal nectar and pollen were abundant food sources during the tracking period and this probably contributed to the selective use of overgrown sisal plantations. The bats also ate large quantities of figs (Ficus grevei during the study, and dispersed seeds of this important pioneer species. The bats flew at an average speed of 9.13 m/s, perhaps to optimise gliding performance. The study confirms that P. rufus has the potential to be a long-distance seed disperser, and is able to fly over a large area, often crossing cleared parts of its habitat. It potentially plays an important role in the regeneration of threatened forest habitats in this biodiversity hotspot.

  18. Sexual specialization in phenology in dioecious Ficus benguetensis and its consequences for the mutualism.

    Science.gov (United States)

    Lin, Shang-Yang; Chou, Lien-Siang; Di Giusto, Bruno; Bain, Anthony

    2015-12-01

    Timing of reproductive events has become central in ecological studies linking success in pollination and seed dispersion to optimizing the probability and periods of encounters with pollinators or dispersers. Obligate plant-insect interactions, especially Ficus-fig wasp mutualisms, offer striking examples of fine-tuned encounter optimization as biological cycles between mutualistic partners are deeply dependent on each other and intertwined over generations. Despite fig flowering phenology being crucial in maintaining Ficus-fig wasp mutualisms, until now, the forces of selection shaping the phenological evolution of dioecious fig trees have received little attention. By conducting a 2-year survey of a population of Ficus benguetensis in Northern Taiwan, we assessed whether environmental factors or other selective pressures shape the phenology of male and female fig trees. Constraints by mutualistic pollinating wasps and seed dispersers, rather than climatic factors, appeared to mainly shape fig phenology and allometry in F. benguetensis. We identified a new sexual specialization in dioecious fig trees: the position of fig production. We propose that the continuous male fig production on tree trunks can enhance the survival of pollinating fig wasps through faster localization of receptive figs while reducing the mutualistic conflict between the fig and its obligate pollinators. By contrast, in female trees, fig production is massive in summer, located on the twigs of the foliar crown and seem more related to seed dispersal and germination. Identifying variations in the allometry and phenology of dioecious figs provide valuable insights into how monoecious and dioecious species resolve mutualism conflicts and into the emergence of dioecy in fig trees.

  19. The Effects of Functional Groups of Dung Beetles on Secondary Seed Dispersal and Goat Dung Removal in Semi Steppe Rangelands-Shahrekord

    Directory of Open Access Journals (Sweden)

    M. Ebrahimi

    2015-06-01

    Full Text Available The present study was conducted to assess effect of dung beetles function on dung removal and seeds dispersion in rangeland of University of Sharekord through completely randomized design in summer. Therefore, the meshes consist of both large and small size was used and filled by goat dung in six treatments (presence of all beetles, absent of the beetles, presence of dwellers and tunnelers, absent of rollers- presence of dwellers, absent of tunnelers and roller- presence of dwellers, presence of small rollers and small tunnelers, absent of large tunnelers and large rollers- Presence of dwellers and small rollers, absent of tunnelers, large rollers with six replications. In order to assess the ecological function of these insects in the seeds translocation, three sizes of plastic beads used as seed mimics. Results illustrated that the maximum function of the dung beetles was calculated at the investigated possible treatment of presence of dwellers, absent of large tunneler and large roller beetles and, present of small tuneller and small roller beetles. Total of 34.02% of dungs were removed. The least dung removal was calculated in the control treatment (absent of beetle, 0.040% and possible treatment of dwellers, large and small tunellers and, also absent and present of large rollers and small rollers (25.06% respectively. Seed removal decreased in the order of: small size (24.40% > medium size (3.73% > large size (1.40%. In general, these insects play an important role in the dung removal and secondary seeds dispersal that with regard to the various factors affecting the function of the beetles, further studies would be needed on investigating deeply different seasons and different dung of live stocks feeding on the rangelands.

  20. A change in SHATTERPROOF protein lies at the origin of a fruit morphological novelty and a new strategy for seed dispersal in medicago genus.

    Science.gov (United States)

    Fourquin, Chloé; del Cerro, Carolina; Victoria, Filipe C; Vialette-Guiraud, Aurélie; de Oliveira, Antonio C; Ferrándiz, Cristina

    2013-06-01

    Angiosperms are the most diverse and numerous group of plants, and it is generally accepted that this evolutionary success owes in part to the diversity found in fruits, key for protecting the developing seeds and ensuring seed dispersal. Although studies on the molecular basis of morphological innovations are few, they all illustrate the central role played by transcription factors acting as developmental regulators. Here, we show that a small change in the protein sequence of a MADS-box transcription factor correlates with the origin of a highly modified fruit morphology and the change in seed dispersal strategies that occurred in Medicago, a genus belonging to the large legume family. This protein sequence modification alters the functional properties of the protein, affecting the affinities for other protein partners involved in high-order complexes. Our work illustrates that variation in coding regions can generate evolutionary novelties not based on gene duplication/subfunctionalization but by interactions in complex networks, contributing also to the current debate on the relative importance of changes in regulatory or coding regions of master regulators in generating morphological novelties.

  1. Effects of mowing date on the opportunities of seed dispersal of ditch bank plant species under different management regimes

    NARCIS (Netherlands)

    Leng, X.; Musters, C.J.M.; Snoo, de G.R.

    2011-01-01

    Mowing and plant removal is a traditional practice in low-intensity farming and likely to lead to high plant species richness. Even today, scientific knowledge on the impact of mowing on seed availability is still very limited. We studied whether the seed availability of ditch bank plant species was

  2. Enhancement of local species richness in tundra by seed dispersal through guts of muskox and barnacle goose

    DEFF Research Database (Denmark)

    Bruun, Hans Henrik; Lundgren, Rebekka; Philipp, Marianne

    2008-01-01

    The potential contribution of vertebrate-mediated seed rain to the maintenance of plant community richness in a High Arctic ecosystem was investigated. We analyzed viable seed content in dung of the four numerically most important terrestrial vertebrates in Northeast Greenland - muskox (Ovibos mo...

  3. Preparation and thermodynamic stability of micron-sized, monodisperse composite polymer particles of disc-like shapes by seeded dispersion polymerization.

    Science.gov (United States)

    Fujibayashi, Teruhisa; Okubo, Masayoshi

    2007-07-17

    Micron-sized, monodisperse composite polymer particles having "disc-like" and "polyhedral" shapes were prepared by seeded dispersion polymerization of 2-ethylhexylmethacrylate (EHMA) with 2.67-mum-sized polystyrene (PS) seed particles in methanol/water media in the presence of droplets of various saturated hydrocarbons and evaporation of the hydrocarbon after the polymerization. Such nonspherical shapes were based on the volume reduction due to the evaporation. The primary factors influencing the particle shape seemed to be the absorption rate of the hydrocarbon into the resulting PS/poly(EHMA)/hydrocarbon composite particles during the polymerization, which affected the viscosities and the volumes of the PS and poly(EHMA) phases. It was found that the morphological development during the polymerization was retarded at "hamburger-like" morphology, which is a precursor of the disc-like particle, although this morphology is a thermodynamically metastable state.

  4. Selective flower abortion maintains moth cooperation in a newly discovered pollination mutualism.

    NARCIS (Netherlands)

    Goto, R.; Okamoto, T.; Kiers, E.T.; Kawakita, A.; Kato, M.

    2010-01-01

    The evolutionary stability of mutualisms is enhanced when partners possess mechanisms to prevent overexploitation by one another. In obligate pollination-seed consumption mutualisms, selective abortion of flowers containing excessive eggs represents one such mechanism, but empirical tests have long

  5. Population genetic structure of the rock outcrop speciesEncholirium spectabile(Bromeliaceae): The role of pollination vs. seed dispersal and evolutionary implications.

    Science.gov (United States)

    Gonçalves-Oliveira, Rodrigo C; Wöhrmann, Tina; Benko-Iseppon, Ana M; Krapp, Florian; Alves, Marccus; Wanderley, Maria das Graças L; Weising, Kurt

    2017-06-01

    Inselbergs are terrestrial, island-like rock outcrop environments that present a highly adapted flora. The epilithic bromeliad Encholirium spectabile is a dominant species on inselbergs in the Caatinga of northeastern Brazil. We conducted a population genetic analysis to test whether the substantial phenotypic diversity of E. spectabile could be explained by limited gene flow among populations and to assess the relative impact of pollen vs. seed dispersal on the genetic structure of the species. Nuclear and chloroplast microsatellite markers were used to genotype E. spectabile individuals from 20 rock outcrop locations, representing four geographic regions: northern Espinhaço Range, Borborema Plateau, southwestern Caatinga and southeastern Caatinga. F -statistics, structure, and other tools were applied to evaluate the genetic makeup of populations. Considerable levels of genetic diversity were revealed. Genetic structuring among populations was stronger on the plastid as compared with the nuclear level, indicating higher gene flow via bat pollination as compared with seed dispersal by wind. structure and AMOVA analyses of the nuclear data suggested a high genetic differentiation between two groups, one containing all populations from the southeastern Caatinga and the other one comprising all remaining samples. The strong genetic differentiation between southeastern Caatinga and the remaining regions may indicate the occurrence of a cryptic species in E. spectabile . The unique genetic composition of each inselberg population suggests in situ conservation as the most appropriate protection measure for this plant lineage. © 2017 Botanical Society of America.

  6. Profiling the Fatty Acids Content of Ornamental Camellia Seeds Cultivated in Galicia by an Optimized Matrix Solid-Phase Dispersion Extraction

    Directory of Open Access Journals (Sweden)

    Carmen Garcia-Jares

    2017-10-01

    Full Text Available Camellia (genus of flowering plants of fam. Theaceae is one of the main crops in Asia, where tea and oil from leaves and seeds have been utilized for thousands of years. This plant is excellently adapted to the climate and soil of Galicia (northwestern Spain and northern Portugal where it is grown not only as an ornamental plant, but to be evaluated as a source of bioactive compounds. In this work, the main fatty acids were extracted from Camellia seeds of four varieties of Camellia: sasanqua, reticulata, japonica and sinensis, by means of matrix-solid phase dispersion (MSPD, and analyzed by gas chromatography (GC with MS detection of the corresponding methyl esters. MSPD constitutes an efficient and greener alternative to conventional extraction techniques, moreover if it is combined with the use of green solvents such as limonene. The optimization of the MSPD extraction procedure has been conducted using a multivariate approach based on strategies of experimental design, which enabled the simultaneous evaluation of the factors influencing the extraction efficiency as well as interactions between factors. The optimized method was applied to characterize the fatty acids profiles of four Camellia varieties seeds, allowing us to compare their fatty acid composition.

  7. Profiling the Fatty Acids Content of Ornamental Camellia Seeds Cultivated in Galicia by an Optimized Matrix Solid-Phase Dispersion Extraction.

    Science.gov (United States)

    Garcia-Jares, Carmen; Sanchez-Nande, Marta; Lamas, Juan Pablo; Lores, Marta

    2017-10-17

    Camellia (genus of flowering plants of fam. Theaceae ) is one of the main crops in Asia, where tea and oil from leaves and seeds have been utilized for thousands of years. This plant is excellently adapted to the climate and soil of Galicia (northwestern Spain) and northern Portugal where it is grown not only as an ornamental plant, but to be evaluated as a source of bioactive compounds. In this work, the main fatty acids were extracted from Camellia seeds of four varieties of Camellia : sasanqua , reticulata , japonica and sinensis , by means of matrix-solid phase dispersion (MSPD), and analyzed by gas chromatography (GC) with MS detection of the corresponding methyl esters. MSPD constitutes an efficient and greener alternative to conventional extraction techniques, moreover if it is combined with the use of green solvents such as limonene. The optimization of the MSPD extraction procedure has been conducted using a multivariate approach based on strategies of experimental design, which enabled the simultaneous evaluation of the factors influencing the extraction efficiency as well as interactions between factors. The optimized method was applied to characterize the fatty acids profiles of four Camellia varieties seeds, allowing us to compare their fatty acid composition.

  8. Interference competition and high temperatures reduce the virulence of fig wasps and stabilize a fig-wasp mutualism.

    Directory of Open Access Journals (Sweden)

    Rui-Wu Wang

    2009-11-01

    Full Text Available Fig trees are pollinated by fig wasps, which also oviposit in female flowers. The wasp larvae gall and eat developing seeds. Although fig trees benefit from allowing wasps to oviposit, because the wasp offspring disperse pollen, figs must prevent wasps from ovipositing in all flowers, or seed production would cease, and the mutualism would go extinct. In Ficus racemosa, we find that syconia ('figs' that have few foundresses (ovipositing wasps are underexploited in the summer (few seeds, few galls, many empty ovules and are overexploited in the winter (few seeds, many galls, few empty ovules. Conversely, syconia with many foundresses produce intermediate numbers of galls and seeds, regardless of season. We use experiments to explain these patterns, and thus, to explain how this mutualism is maintained. In the hot summer, wasps suffer short lifespans and therefore fail to oviposit in many flowers. In contrast, cooler temperatures in the winter permit longer wasp lifespans, which in turn allows most flowers to be exploited by the wasps. However, even in winter, only in syconia that happen to have few foundresses are most flowers turned into galls. In syconia with higher numbers of foundresses, interference competition reduces foundress lifespans, which reduces the proportion of flowers that are galled. We further show that syconia encourage the entry of multiple foundresses by delaying ostiole closure. Taken together, these factors allow fig trees to reduce galling in the wasp-benign winter and boost galling (and pollination in the wasp-stressing summer. Interference competition has been shown to reduce virulence in pathogenic bacteria. Our results show that interference also maintains cooperation in a classic, cooperative symbiosis, thus linking theories of virulence and mutualism. More generally, our results reveal how frequency-dependent population regulation can occur in the fig-wasp mutualism, and how a host species can 'set the rules of the

  9. Seed dispersal and establishment of endangered plants on Oceanic Islands: the Janzen-Connell model, and the use of ecological analogues.

    Directory of Open Access Journals (Sweden)

    Dennis M Hansen

    Full Text Available BACKGROUND: The Janzen-Connell model states that plant-specific natural enemies may have a disproportionately large negative effect on progeny close to maternal trees. The majority of experimental and theoretical studies addressing the Janzen-Connell model have explored how it can explain existing patterns of species diversity in tropical mainland areas. Very few studies have investigated how the model's predictions apply to isolated oceanic islands, or to the conservation management of endangered plants. Here, we provide the first experimental investigation of the predictions of the Janzen-Connell model on an oceanic island, in a conservation context. In addition, we experimentally evaluate the use of ecological analogue animals to resurrect the functional component of extinct frugivores that could have dispersed seeds away from maternal trees. METHODOLOGY/PRINCIPAL FINDINGS: In Mauritius, we investigated seed germination and seedling survival patterns of the critically endangered endemic plant Syzygium mamillatum (Myrtaceae in relation to proximity to maternal trees. We found strong negative effects of proximity to maternal trees on growth and survival of seedlings. We successfully used giant Aldabran tortoises as ecological analogues for extinct Mauritian frugivores. Effects of gut-passage were negative at the seed germination stage, but seedlings from gut-passed seeds grew taller, had more leaves, and suffered less damage from natural enemies than any of the other seedlings. CONCLUSIONS/SIGNIFICANCE: We provide the first experimental evidence of a distance-dependent Janzen-Connell effect on an oceanic island. Our results potentially have serious implications for the conservation management of rare plant species on oceanic islands, which harbour a disproportionately large fraction of the world's endemic and endangered plants. Furthermore, in contrast to recent controversy about the use of non-indigenous extant megafauna for re

  10. Small-scale indirect effects determine the outcome of a tripartite plant-disperser-granivore interaction.

    Science.gov (United States)

    Boulay, Raphaël; Carro, Francisco; Soriguer, Ramón C; Cerdá, Xim

    2009-09-01

    The microhabitat in which plants grow affects the outcome of their interactions with animals, particularly non-specialist consumers. Nevertheless, as most research on this topic has dealt with either mutualists or antagonists, little is known about the indirect effects of plant microhabitats on the outcome of tripartite interactions involving plants and both mutualists (e.g. seed dispersers) and antagonists (e.g. granivores). During three consecutive years, we analysed small-scale variations in the interaction of a perennial myrmecochore, Helleborus foetidus, with its seed dispersers and consumers as a function of the intensity of plant cover. Most seeds were released during the day and were rapidly removed by ants. Nevertheless, the proportion of ant-removed seeds was higher for plants located in open microhabitats than for plants surrounded by dense vegetation and rocky cover. Ant sampling revealed that seed removers were equally abundant, irrespective of the level of cover. By contrast, a few tiny ant species that feed on the reward without transporting the seeds were more abundant in highly covered microhabitats, irrespective of hellebore diaspore availability. These "cheaters" decrease the chance of removal by removers and increase the probability of seeds remaining on the ground until night, when granivore mice Apodemus sylvaticus become active. Mice also preferred foraging in covered microhabitats, where they consumed a larger proportion of seeds. Therefore, the density of cover indirectly increased seed predation risk by attracting more seed predators and cheater ants that contribute to increase seed availability for seed predators. Our results emphasize the importance of considering the indirect effects of plant microhabitat on their dispersal success. They highlight the indirect effect of cheaters that are likely to interfere in mutualisms and may lead to their collapse unless external factors such as spatio-temporal heterogeneity in seed availability

  11. Pollination and seed dispersal by lizards: a review Polinización y dispersión de semillas por lagartijas: una revisión

    Directory of Open Access Journals (Sweden)

    HÉCTOR GODÍNEZ-ALVAREZ

    2004-09-01

    Full Text Available This paper reviews the ecological literature published during the last 15 years on pollination and seed dispersal by lizards, in order to determine the possible effects of these animals on plant reproduction. This review is only limited to these years because articles on plant-lizard interactions during this period have used more rigorous experimental approaches than those made previously. All compiled data were analyzed considering the conceptual framework provided by the quantity and quality components of pollination and seed dispersal (i.e., effectiveness, since this information is essential to have an idea of the relative contribution of animals to plant fitness. Results showed that 34 species of lizards feed on nectar and fruits of plants. While lizards consume these plant materials, they could effectively pollinate flowers or disperse seeds to sites away from parent plants. However, more studies on particular aspects of these interactions should be conducted in order to completely understand the ecological and evolutionary effects of lizards on plantsEn este artículo se presenta una revisión de la literatura ecológica publicada durante los últimos 15 años sobre la polinización y la dispersión de las semillas por lagartijas, para determinar los posibles efectos de estos animales sobre la reproducción de las plantas. Esta revisión está limitada solamente a estos años debido a que los artículos sobre las interacciones planta-lagartija realizados en este periodo emplearon protocolos experimentales más rigurosos que los trabajos hechos anteriormente. Toda la información obtenida se analizó tomando como base las ideas relacionadas con los componentes de cantidad y calidad de la polinización y la dispersión de las semillas (i.e., efectividad, debido a que estos componentes permiten tener una idea de la contribución relativa de los animales a la adecuación de las plantas. Los resultados mostraron que 34 especies de lagartijas se

  12. Evolution of fruit traits in ficus subgenus Sycomorus (Moraceae): to what extent do frugivores determine seed dispersal mode?

    Science.gov (United States)

    Harrison, Rhett D; Rønsted, Nina; Xu, Lei; Rasplus, Jean-Yves; Cruaud, Astrid

    2012-01-01

    Fig trees are a ubiquitous component of tropical rain forests and exhibit an enormous diversity of ecologies. Focusing on Ficus subgenus Sycomorus, a phenotypically diverse and ecologically important Old World lineage, we examined the evolution of fruit traits using a molecular phylogeny constructed using 5 kilobases of DNA sequence data from 63 species (50% of global diversity). In particular, we ask whether patterns of trait correlations are consistent with dispersal agents as the primary selective force shaping morphological diversity or if other ecological factors may provide a better explanation? Fig colour, size and placement (axial, cauliflorous, or geocarpic) were all highly evolutionarily liable, and the same fruit traits have evolved in different biogeographic regions with substantially different dispersal agents. After controlling for phylogenetic autocorrelation, we found that fig colour and size were significantly associated with fig placement and plant-life history traits (maximum plant height and leaf area, respectively). However, contrary to prevailing assumptions, fig placement correlated poorly with known dispersal agents and appears more likely determined by other factors, such as flowering phenology, nutrient economy, and habitat preference. Thus, plant life-history, both directly and through its influence on fig placement, appears to have played a prominent role in determining fruit traits in these figs.

  13. Minimizing Mutual Couping

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed herein are techniques, systems, and methods relating to minimizing mutual coupling between a first antenna and a second antenna.......Disclosed herein are techniques, systems, and methods relating to minimizing mutual coupling between a first antenna and a second antenna....

  14. Danish mutual fund performance

    DEFF Research Database (Denmark)

    Christensen, Michael

    2013-01-01

    This article provides the first independent performance analysis of Danish mutual funds. We analyse selectivity and market timing abilities for 71 mutual funds that have been in operation from 2001 to 2010. The results show great fund performance diversity. Half the funds have performed neutrally...

  15. Sleeping sites and latrines of spider monkeys in continuous and fragmented rainforests: implications for seed dispersal and forest regeneration.

    Directory of Open Access Journals (Sweden)

    Arturo González-Zamora

    Full Text Available Spider monkeys (Ateles geoffroyi use sites composed of one or more trees for sleeping (sleeping sites and sleeping trees, respectively. Beneath these sites/trees they deposit copious amounts of dung in latrines. This behavior results in a clumped deposition pattern of seeds and nutrients that directly impacts the regeneration of tropical forests. Therefore, information on the density and spatial distribution of sleeping sites and latrines, and the characteristics (i.e., composition and structure of sleeping trees are needed to improve our understanding of the ecological significance of spider monkeys in influencing forest composition. Moreover, since primate populations are increasingly forced to inhabit fragmented landscapes, it is important to assess if these characteristics differ between continuous and fragmented forests. We assessed this novel information from eight independent spider monkey communities in the Lacandona rainforest, Mexico: four continuous forest sites and four forest fragments. Both the density of sleeping sites and latrines did not differ between forest conditions. Latrines were uniformly distributed across sleeping sites, but the spatial distribution of sleeping sites within the areas was highly variable, being particularly clumped in forest fragments. In fact, the average inter-latrine distances were almost double in continuous forest than in fragments. Latrines were located beneath only a few tree species, and these trees were larger in diameter in continuous than fragmented forests. Because latrines may represent hotspots of seedling recruitment, our results have important ecological and conservation implications. The variation in the spatial distribution of sleeping sites across the forest indicates that spider monkeys likely create a complex seed deposition pattern in space and time. However, the use of a very few tree species for sleeping could contribute to the establishment of specific vegetation associations

  16. Sleeping sites and latrines of spider monkeys in continuous and fragmented rainforests: implications for seed dispersal and forest regeneration.

    Science.gov (United States)

    González-Zamora, Arturo; Arroyo-Rodríguez, Víctor; Oyama, Ken; Sork, Victoria; Chapman, Colin A; Stoner, Kathryn E

    2012-01-01

    Spider monkeys (Ateles geoffroyi) use sites composed of one or more trees for sleeping (sleeping sites and sleeping trees, respectively). Beneath these sites/trees they deposit copious amounts of dung in latrines. This behavior results in a clumped deposition pattern of seeds and nutrients that directly impacts the regeneration of tropical forests. Therefore, information on the density and spatial distribution of sleeping sites and latrines, and the characteristics (i.e., composition and structure) of sleeping trees are needed to improve our understanding of the ecological significance of spider monkeys in influencing forest composition. Moreover, since primate populations are increasingly forced to inhabit fragmented landscapes, it is important to assess if these characteristics differ between continuous and fragmented forests. We assessed this novel information from eight independent spider monkey communities in the Lacandona rainforest, Mexico: four continuous forest sites and four forest fragments. Both the density of sleeping sites and latrines did not differ between forest conditions. Latrines were uniformly distributed across sleeping sites, but the spatial distribution of sleeping sites within the areas was highly variable, being particularly clumped in forest fragments. In fact, the average inter-latrine distances were almost double in continuous forest than in fragments. Latrines were located beneath only a few tree species, and these trees were larger in diameter in continuous than fragmented forests. Because latrines may represent hotspots of seedling recruitment, our results have important ecological and conservation implications. The variation in the spatial distribution of sleeping sites across the forest indicates that spider monkeys likely create a complex seed deposition pattern in space and time. However, the use of a very few tree species for sleeping could contribute to the establishment of specific vegetation associations typical of the

  17. Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry

    Science.gov (United States)

    He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

    2016-12-01

    Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g-1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

  18. Seed development and carbohydrates

    NARCIS (Netherlands)

    Wittich, P.E.

    1998-01-01

    Seeds assure the plant the onset of a next generation and a way of dispersal. They consist of endosperm and an embryo (originating from gametophytic tissue), enveloped by a seed coat (sporophytic tissue). Plants generate different types of seeds. For instance, the endosperm may either be

  19. Evolution of mutualism between species

    Energy Technology Data Exchange (ETDEWEB)

    Post, W.M.; Travis, C.C.; DeAngelis, D.L.

    1980-01-01

    Recent theoretical work on mutualism, the interaction between species populations that is mutually beneficial, is reviewed. Several ecological facts that should be addressed in the construction of dynamic models for mutualism are examined. Basic terminology is clarified. (PSB)

  20. Integrating plant carbon dynamics with mutualism ecology.

    Science.gov (United States)

    Pringle, Elizabeth G

    2016-04-01

    Plants reward microbial and animal mutualists with carbohydrates to obtain nutrients, defense, pollination, and dispersal. Under a fixed carbon budget, plants must allocate carbon to their mutualists at the expense of allocation to growth, reproduction, or storage. Such carbon trade-offs are indirectly expressed when a plant exhibits reduced growth or fecundity in the presence of its mutualist. Because carbon regulates the costs of all plant mutualisms, carbon dynamics are a common platform for integrating these costs in the face of ecological complexity and context dependence. The ecophysiology of whole-plant carbon allocation could thus elucidate the ecology and evolution of plant mutualisms. If mutualisms are costly to plants, then they must be important but frequently underestimated sinks in the terrestrial carbon cycle. © 2015 The Author. New Phytologist © 2015 New Phytologist Trust.

  1. Ants, rodents and seed predation in Proteaceae

    African Journals Online (AJOL)

    . Saasveld Forestry Research Centre, George. Many species of Cape Proteaceae have seeds dispersed by ants. Ants may reduce seed predation by rapidly transporting and burying seeds in their nests. Three field experiments using ant and ...

  2. Empty seeds are not always bad: simultaneous effect of seed emptiness and masting on animal seed predation.

    Directory of Open Access Journals (Sweden)

    Ramón Perea

    Full Text Available Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal and in two contrasting microsites (open vs. sheltered to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis. In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P. Parthenocarpy (non-fertilized seeds was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed.

  3. Empty seeds are not always bad: simultaneous effect of seed emptiness and masting on animal seed predation.

    Science.gov (United States)

    Perea, Ramón; Venturas, Martin; Gil, Luis

    2013-01-01

    Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal) and in two contrasting microsites (open vs. sheltered) to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis). In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P). Parthenocarpy (non-fertilized seeds) was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds) did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators) consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed.

  4. Seed dispersal of Solanum thomasiifolium Sendtner (Solanaceae in the Linhares Forest, Espírito Santo state, Brazil Dispersão de sementes de Solanum thomasiifolium Sendtner (Solanaceae na Floresta de Linhares, Espírito Santo, Brasil

    Directory of Open Access Journals (Sweden)

    João Vasconcellos-Neto

    2009-12-01

    Full Text Available The aim of this study was to analyse seed dispersal and establishment of Solanum thomasiifolium in an area of "nativo" vegetation in Espirito Santo state on the southeastern Brazilian coast. Ten species of birds, the crab-eating fox (Cerdocyon thous, and one species of lizard (Tropidurus torquatus fed on S. thomasiifolium fruits and dispersed viable seeds in their faeces. The proportional contribution of each of these groups to seed dispersal was 77% (birds, 19% (crab-eating fox and 4% (lizards. Ants also contributed to seed dispersal. More seeds were deposited in vegetation islands than in the surrounding open areas. Germination rates of seeds collected directly from fruit (control, bird droppings, the faeces of crab-eating foxes and lizards were, respectively, 64, 64, 53, and 80 %. Differences among these rates were all significant, except between birds and control. Lizards were important as seed carriers between nearby islands and they expelled a higher proportion of viable seeds. Birds and the crab-eating foxes did not enhance seed germination, but promoted seed dispersal over a wider area. Plant architecture, fruit productivity, fruit characteristics and the diversity of frugivores are important for the success of S. thomasiifolium in habitat colonization.O propósito deste estudo foi analisar a dispersão de sementes e o estabelecimento de Solanum thomasiifolium em uma área de vegetação de "nativo" no Estado do Espírito Santo, na costa do sudeste do Brasil. Dez espécies de aves, o cachorro-do-mato (Cerdocyon thous e uma espécie de lagarto (Tropidurus torquatus alimentaram-se de frutos de S. thomasiifolium e dispersaram sementes viáveis em suas fezes. A contribuição proporcional de cada um destes grupos na dispersão de sementes foi de 77% para aves, 19% para o cachorro-do-mato e 4% para o lagarto. Formigas também contribuíram com a dispersão de sementes. Mais sementes foram depositadas nas ilhas de vegetação do que nas

  5. Mutually unbiased bases

    Indian Academy of Sciences (India)

    Mutually unbiased bases play an important role in quantum cryptography [2] and in the optimal determination of the density operator of an ensemble [3,4]. A density operator ρ in N-dimensions depends on N2 1 real quantities. With the help of MUB's, any such density operator can be encoded, in an optimal way, in terms of ...

  6. Mutually unbiased bases

    Indian Academy of Sciences (India)

    Abstract. After a brief review of the notion of a full set of mutually unbiased bases in an N- dimensional Hilbert space, we summarize the work of Wootters and Fields (W K Wootters and. B C Fields, Ann. Phys. 191, 363 (1989)) which gives an explicit construction for such bases for the case N pr, where p is a prime. Further, we ...

  7. Frugivoria e dispersão de sementes pelo lagarto teiú Tupinambis merianae (Reptilia: Teiidae Frugivory and seed dispersal by the tegu lizard Tupinambis merianae Reptilia: Teiidae

    Directory of Open Access Journals (Sweden)

    Everaldo Rodrigo de Castro

    2004-01-01

    Full Text Available Os lagartos teiús possuem uma dieta generalista, podendo agir como importantes dispersores de sementes em florestas semidecíduas do sudeste do Brasil. Foram estudadas a frugivoria e a dispersão de sementes de lagartos teiús usando animais em cativeiro, através da oferta de frutos de uma floresta semidecídua. Frutos de trinta espécies vegetais foram oferecidos aos lagartos em cativeiro, com diâmetro variando de 0,81 a 10,0 cm. Não foram encontradas diferenças estatísticas na germinação entre as sementes que passaram pelo trato digestivo do lagarto e as controle de Eugenia uniflora (chi²= 0.69, P>0.50, Genipa americana (chi²= 6.4, P>0.975, Cereus peruvianus (chi²= 0.018, P>0.10, e Solanum viarum (chi²= 6.23, P>0.975. O tempo de retenção da semente no tubo digestivo do teiú variou de 22 a 23 h para Solanum lycocarpum e 43 a 44 h para Syagrus romanzoffiana. Nossos resultados indicam que o lagarto teiú tem potencial para agir como um importante dispersor de sementes nos trópicos.Tegu lizards have a generalist diet and may play an important role as seed dispersers in semideciduous forests in south-east Brazil. We studied the frugivory and seed dispersal of tegu lizards using captive animals and offering wild fruits from a semideciduous forest. Thirty fruit species were eaten by the lizards in captivity, ranging from 0.81 to 10.0 cm (fruit diameter. Even large fruit adapted to dispersal by large mammals were swallowed (ex. Syagrus oleracea. There were no statistical differences in seed germination between seeds that passed through the lizard gut and the control in Eugenia uniflora (chi2 = 0.69, P>0.50, Genipa americana (chi2 = 6.4, P>0.975, Cereus peruvianus (chi2 = 0.018, P>0.10, and Solanum viarum (chi2 = 6.23, P>0.975. Seed retention time in the tegu gut ranged from 2224 h (Solanum lycocarpum to 4344 h (for Syagrus romanzoffiana. Our results indicate that tegu lizards have a potential to be an important seed dispersers in the

  8. Sugar maple seed production in northern New Hampshire

    Science.gov (United States)

    Peter W. Garrett; Raymond E. Graber

    1995-01-01

    Large numbers of sugar maple seed are dispersed every second or third year. Very little seed was damaged by insects or mammals prior to dispersal. The trapping methods used prevented major losses following seed fall. Seed production was positively correlated with tree diameter but not with age of seed trees.

  9. Harmonization versus Mutual Recognition

    DEFF Research Database (Denmark)

    Jørgensen, Jan Guldager; Schröder, Philipp

    with the opportunity to start export sales. In contrast, harmonization, in particular the prospect that one’s own national (but not the foreign) standard becomes the only globally accepted standard, opens the foreign market without balancing entry at home. We study these scenarios in a reduced form lobby game with two......, harmonized standards may fail to harvest the full pro-competitive effects from trade liberalization compared to mutual recognition; moreover, the issue is most pronounced in markets featuring price competition....

  10. Deep Mutual Learning

    OpenAIRE

    Zhang, Ying; Xiang, Tao; Hospedales, Timothy M.; Lu, Huchuan

    2017-01-01

    Model distillation is an effective and widely used technique to transfer knowledge from a teacher to a student network. The typical application is to transfer from a powerful large network or ensemble to a small network, that is better suited to low-memory or fast execution requirements. In this paper, we present a deep mutual learning (DML) strategy where, rather than one way transfer between a static pre-defined teacher and a student, an ensemble of students learn collaboratively and teach ...

  11. Validating Farmers' Indigenous Social Networks for Local Seed Supply in Central Rift Valley of Ethiopia

    NARCIS (Netherlands)

    Seboka, B.; Deressa, A.

    2000-01-01

    Indigenous social networks of Ethiopian farmers participate in seed exchange based on mutual interdependence and trust. A government-imposed extension program must validate the role of local seed systems in developing a national seed industry

  12. Validating Farmers' Indigenous Social Networks for Local Seed Supply in Central Rift Valley of Ethiopia.

    Science.gov (United States)

    Seboka, B.; Deressa, A.

    2000-01-01

    Indigenous social networks of Ethiopian farmers participate in seed exchange based on mutual interdependence and trust. A government-imposed extension program must validate the role of local seed systems in developing a national seed industry. (SK)

  13. Frugivoría y dispersión de semillas de la palma Oenocarpus bataua (Arecaceae en un bosque de los Andes colombianos Frugivory and seed dispersal Oenocarpus bataua palm (Arecaceae in a forest from the Colombian Andes

    Directory of Open Access Journals (Sweden)

    Rosario Rojas-Robles

    2012-12-01

    Full Text Available En zonas bajas tropicales, en bosques continuos y relativamente poco intervenidos, los frutos de la palma Oenocarpus bataua Mart., son consumidos por diversas especies de vertebrados, sin embargo, no hay estudios de dispersión de más largo plazo con esta especie. Entre agosto 2005-septiembre 2006 se realizaron observaciones de remoción de frutos, conteo de frutos comidos, observaciones focales, registros de frugivoría mediante trampas fotográficas, experimentos de dispersión y parcelas para determinar distribución espacial de Oenocarpus bataua. Cinco especies de mamíferos comen, dispersan, entierran (Sciurus granatensis, Microsciurus mimulus, Dasyprocta punctata y Proechimys sp., tapan (Marmosa robinsoni y llevan a las cuevas (Marmosa robinsoni y Proechimys sp., los frutos de O. bataua, sin dañar la semilla. El 21.7% de los frutos fueron dispersados, 13.2% roídos o pelados, 5.6% tapados, enterrados y llevados a cuevas. La distancia media de remoción de semillas y frutos fue 3.1m, aunque en menor proporción se registraron eventos de dispersión > a 50m. La abundante producción, el tamaño, el peso, la intensa remoción de los frutos por frugívoros, las cortas distancias de dispersión, la ausencia de frugívoros de gran porte disminuidos por cacería y fragmentación, encargados de la dispersión de larga distancia y el aumento de roedores, especialmente ardillas que presionan fuertemente el recurso frutos, generan una lluvia de semillas espacialmente restringida, posiblemente responsable de los patrones de distribución agregados en semillas, plántulas y posteriormente en juveniles y sub-adultos.Seed dispersal is a key process that determines the spatial structure and dynamics of populations of plants, establishes the potential area of recruitment and in this way, the basis for subsequent processes such as predation, germination, competition and growth. The purpose of this research was to identify the guild of frugivores of the

  14. Evidence for a trade-off strategy in stone oak (Lithocarpus seeds between physical and chemical defense highlights fiber as an important antifeedant.

    Directory of Open Access Journals (Sweden)

    Xi Chen

    Full Text Available Trees in the beech or oak family (Fagaceae have a mutualistic relationship with scatter-hoarding rodents. Rodents obtain nutrients and energy by consuming seeds, while providing seed dispersal for the tree by allowing some cached seeds to germinate. Seed predation and caching behavior of rodents is primarily affected by seed size, mechanical protection, macronutrient content, and chemical antifeedants. To enhance seed dispersal, trees must optimize trade-offs in investment between macronutrients and antifeedants. Here, we examine this important chemical balance in the seeds of tropical stone oak species with two substantially different fruit morphologies. These two distinct fruit morphologies in Lithocarpus differ in the degree of mechanical protection of the seed. For 'acorn' fruit, a thin exocarp forms a shell around the seed while for 'enclosed receptacle' (ER fruit, the seed is embedded in a woody receptacle. We compared the chemical composition of numerous macronutrient and antifeedant in seeds from several Lithocarpus species, focusing on two pairs of sympatric species with different fruit morphologies. We found that macronutrients, particularly total non-structural carbohydrate, was more concentrated in seeds of ER fruits while antifeedants, primarily fibers, were more concentrated in seeds of acorn fruits. The trade-off in these two major chemical components was more evident between the two sympatric lowland species than between two highland species. Surprisingly, no significant difference in overall tannin concentrations in the seeds was observed between the two fruit morphologies. Instead, the major trade-off between macronutrients and antifeedants involved indigestible fibers. Future studies of this complex mutualism should carefully consider the role of indigestible fibers in the foraging behavior of scatter-hoarding rodents.

  15. Ants sow the seeds of global diversification in flowering plants.

    Directory of Open Access Journals (Sweden)

    Szabolcs Lengyel

    Full Text Available The extraordinary diversification of angiosperm plants in the Cretaceous and Tertiary periods has produced an estimated 250,000-300,000 living angiosperm species and has fundamentally altered terrestrial ecosystems. Interactions with animals as pollinators or seed dispersers have long been suspected as drivers of angiosperm diversification, yet empirical examples remain sparse or inconclusive. Seed dispersal by ants (myrmecochory may drive diversification as it can reduce extinction by providing selective advantages to plants and can increase speciation by enhancing geographical isolation by extremely limited dispersal distances.Using the most comprehensive sister-group comparison to date, we tested the hypothesis that myrmecochory leads to higher diversification rates in angiosperm plants. As predicted, diversification rates were substantially higher in ant-dispersed plants than in their non-myrmecochorous relatives. Data from 101 angiosperm lineages in 241 genera from all continents except Antarctica revealed that ant-dispersed lineages contained on average more than twice as many species as did their non-myrmecochorous sister groups. Contrasts in species diversity between sister groups demonstrated that diversification rates did not depend on seed dispersal mode in the sister group and were higher in myrmecochorous lineages in most biogeographic regions.Myrmecochory, which has evolved independently at least 100 times in angiosperms and is estimated to be present in at least 77 families and 11 000 species, is a key evolutionary innovation and a globally important driver of plant diversity. Myrmecochory provides the best example to date for a consistent effect of any mutualism on large-scale diversification.

  16. Dispersão de sementes de uruvalheira (Platypodium elegans vog. (Fabaceae em um cerradão, Uberlândia-MG Seeds dispersal of uruvalheira (Platypodium elegans vog. (Fabaceae in cerradão, Uberlandia, MG

    Directory of Open Access Journals (Sweden)

    Sérgio de Faria Lopes

    2010-10-01

    Full Text Available Estudou-se a dispersão de sementes de cinco árvores-matriz de Platypodium elegans Vog. (Fabaceae em área de cerradão, na Estação Ecológica do Panga (EEP. As amostragens foram feitas em parcelas de 0,25 m2, posicionadas em linhas partindo da base da matriz em direção aos quatro pontos cardeais (Norte, Sul, Leste e Oeste, marcadas a cada metro. No laboratório, os frutos foram abertos para análise da qualidade das sementes. Foram amostradas 1.131 sementes, das quais 18,4% estavam intactas e 81,6%, danificadas e provavelmente inviáveis para germinação. A dispersão das sementes sofreu influência da topografia do local das matrizes, das respostas fisiológicas e genéticas à pré-dispersão, bem como do possível direcionamento favorável do vento. Dessa forma, a atuação conjunta desses fatores funcionaria como facilitadores relevantes na formação do banco de sementes e moldaria a probabilidade de estabelecimento de novos indivíduos, tanto na área estudada quanto nas fisionomias adjacentes..It was studied seeds dispersal of five first trees of Platypodium elegans Vog. (Fabaceae, in area of cerradão in the Estação Ecológica do Panga (EEP. The samplings had been made in 0,25 plots of m2, located in lines leaving of the base of the matrix in direction to the four points cardinals (north, south, east and west, marked to each meter. The fruits had been opened for analysis of the quality of the seeds. A total of 1.131 seeds was collected in the sampling area of the five arrays, of which 18,4% they were viable and 81,6% probably impracticable for germination. The dispersion of the seeds suffered influence from the topography of the place of the matrices, of the physiological and genetic answers daily early-dispersion, as well as of the possible favorable aiming of the wind. The joint action of these factors serves as relevant facilitators on the seed bank training as so as the probability of establishment of new individuals both in

  17. Rating mutual funds

    DEFF Research Database (Denmark)

    Bechmann, Ken L.; Rangvid, Jesper

    2007-01-01

    We develop a new rating of mutual funds: the atpRating. The atpRating assigns crowns to each individual mutual fund based upon the costs an investor pays when investing in the fund in relation to what it would cost to invest in the fund's peers. Within each investment category, the rating assigns...... five crowns to funds with the lowest costs and one crown to funds with the highest costs. We investigate the ability of the atpRating to predict the future performance of a fund. We find that an investor who has invested in the funds with the lowest costs within an investment category would have...... obtained a risk-adjusted excess return that is approximately 3-4 percentage points higher per annum than if the funds with the highest costs had been invested in. We compare the atpRating with the Morningstar Rating. We show that one reason why the atpRating and the Morningstar Rating contain different...

  18. Rating mutual funds

    DEFF Research Database (Denmark)

    Bechmann, Ken L.; Rangvid, Jesper

    We develop a new rating of mutual funds: the atpRating. The atpRating assigns crowns to each individual mutual fund based upon the costs an investor pays when investing in the fund in relation to what it would cost to invest in the fund's peers. Within each investment category, the rating assigns...... five crowns to funds with the lowest costs and one crown to funds with the highest costs. We investigate the ability of the atpRating to predict the future performance of a fund. We find that an investor who has invested in the funds with the lowest costs within an investment category would have...... obtained an annual risk-adjusted excess return that is approximately 3-4 percentage points higher per annum than if the funds with the highest costs had been invested in. We compare the atpRating with the Morningstar Rating. We show that one reason why the atpRating and the Morningstar Rating contain...

  19. Mutual aid fund commission

    CERN Multimedia

    Staff Association

    2011-01-01

    The composition of the Board of the Mutual Aid Fund for 2011 is as follows: President: Pascal Droux Vice-president: Connie Potter Treasurer: Louis Pereira Deputy treasurer: Barbara Brugger Secretary: Sonia Casenove Deputy secretary: Isabelle Mardirossian Members: Christopher David Thomas   Jean-Claude Vialis (GAC member)   Marie-Luce Falipou   Gunilla Santiard (Jean-Claude Vialis’s alternate) The role of the Fund is to provide financial help to members of personnel and beneficiaries of the Pension Fund who are in need of exceptional financial assistance. All requests are treated in the strictest confidence. Should you wish to apply for aid from the Fund, kindly contact any member of the Board as given above or Social Services, tel.74479 – 73867.

  20. Mutual capacitor and its applications

    Directory of Open Access Journals (Sweden)

    Chun Li

    2014-06-01

    Full Text Available This study presents a new ac circuit element – the mutual capacitor, being a dual of the mutual inductor, which is also a new ac transformer. This element is characteristic of the mutual-capacitance coupling of a multi-capacitance system. A unity-coupled mutual capacitor works as an ideal current or voltage transformer, and incidentally acts as waveform separating when inductor employed or waveform converting from square-wave to quasi-sine or waveform filtering, between ports. As a transformer, the mutual capacitor is easy to design, easy for heat cooling, more accurate for current or voltage transformation, dissipating less energy as well as saving materials, suitable for high-power and high-voltage applications. Experiments to demonstrate performances of unity-coupled mutual capacitors are also given.

  1. Araucaria araucana and the Austral parakeet: pre-dispersal seed predation on a masting species El pehuén y la cachaña: depredación predispersión de una especie "masting"

    Directory of Open Access Journals (Sweden)

    JOHN D SHEPHERD

    2008-09-01

    Full Text Available Pre-dispersal seed predation by Austral parakeets, Enicognathus ferrugineus, on pehuén, Araucaria araucana, was studied to assess the relationship between predation and seed production. We collected falling seeds in four araucaria forests of southwestern Neuquén Province, Argentina during four years that included both mast and intermast years. Predation rates were negatively correlated with seed production. When seed production was high, predation rates ranged from 0.6 to 3.3 %; when it was low, predation rates ranged from 13.0 to 20.6 %. Years differed in the pattern of monthly seed fall with peak seed fall in March 2002 and April 2003. Predation rates were lower and more uniform in the year of higher seed production, but did not differ between sites. In an intermast year, predation rates increased during the season, reaching their highest rates after peak seed fall. Parakeets handled seeds differently in mast and intermast years, dropping fewer slightly-damaged seeds when production was low. We discuss these results in the context of the predator satiation hypothesis.Se estudió la depredación predispersión de semillas del Pehuén, Araucaria araucana, por la cachaña, Enicognathus ferrugineus, para evaluar la relación entre depredación y producción de semillas. Durante cuatro años, incluyendo años de alta ("semillazón" y baja producción de semillas, se colectaron semillas caídas de los árboles en bosques del sudoeste de la Provincia del Neuquén, Argentina. Se detectó una correlación negativa entre depredación y producción de semillas. En los años de alta y baja producción de semillas, las tasas de depredación variaron entre 0,6 y 3,3 % y entre 13,0 y 20,6 %, respectivamente. Entre años existe una variación en el patrón temporal de caída de semillas, con picos de caída en marzo y abril para 2002 y 2003, respectivamente. La tasa de depredación de semillas fue más baja y uniforme en el año de alta producción de conos

  2. An overlooked plant–parakeet mutualism counteracts human overharvesting on an endangered tree

    Science.gov (United States)

    Gleiser, Gabriela; Tella, José L.; Hiraldo, Fernando; Aizen, Marcelo A.

    2018-01-01

    The exponential growth of the human population often causes the overexploitation of resources and disruption of ecological interactions. Here, we propose that the antagonist effect of humans on exploited species might be alleviated with the advent of a second predator species. We focused on the complex interactions between an endangered conifer (Araucaria araucana) and two seed exploiters: the Austral parakeet (Enicognathus ferrugineus) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape from human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human seed collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism–mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation. PMID:29410848

  3. An overlooked plant-parakeet mutualism counteracts human overharvesting on an endangered tree.

    Science.gov (United States)

    Speziale, Karina L; Lambertucci, Sergio A; Gleiser, Gabriela; Tella, José L; Hiraldo, Fernando; Aizen, Marcelo A

    2018-01-01

    The exponential growth of the human population often causes the overexploitation of resources and disruption of ecological interactions. Here, we propose that the antagonist effect of humans on exploited species might be alleviated with the advent of a second predator species. We focused on the complex interactions between an endangered conifer ( Araucaria araucana ) and two seed exploiters: the Austral parakeet ( Enicognathus ferrugineus ) and human seed collectors. We tested the importance of partial seed consumption by parakeets as an escape from human seed harvesting. Although parakeets frequently ate whole seeds, a substantial proportion of the seeds found under trees were only partially eaten and avoided by human seed collectors. These seeds germinated at a similar proportion but faster than intact seeds under laboratory conditions. Our results revealed an overlooked mutualism between parakeets and an endangered tree. Incomplete seed eating by parakeets, plus selection against these eaten seeds by humans, may enhance regeneration possibilities for this conifer species subject to human seed collection, turning the scale of the antagonism-mutualism continuum to the mutualistic side. In this context, parakeets might be providing an important service in those forests subject to human harvesting by allowing a fraction of seeds to escape human predation.

  4. Gene regulation in seeds : insights into translational dynamics

    NARCIS (Netherlands)

    Bai, B.

    2016-01-01

    Seeds are unique structures in the plant life cycle. The variation in the timing of seed maturation, dispersion, and the establishment of seed dormancy and longevity, increases the chances of plant survival and enlarge the distance that plants could disperse in the natural habitat. Seeds contain

  5. Role of Brycinus lateralis (Teleostei: Alestidae) in dispersal and ...

    African Journals Online (AJOL)

    Seed passage through the gut of vertebrates can be important for seed dispersal, but might influence seed viability. The ability of seeds to germinate after ingestion by seed-eating fish is important for the population dynamics of some plant species, and significant in the evolution of plant–fish interactions. Certain fish in the ...

  6. Does adaptive strategy for delayed seed dispersion affect extinction probability of a desert species? an assessment using the population viability analysis and glass house experiment

    Directory of Open Access Journals (Sweden)

    Manish Mathur

    2014-10-01

    Full Text Available Canopy seed bank is an important adaptive evolutionary trait that provides various types of protection to the seeds. However, costing of such evolutionary trait on plant survival is largely unknown. Present investigation provided a new insight on the serotonious habit of Blepharis sindica associated with its endangerment status. Extinction probabilities of two available population of B. sindica were quantified using two types of census data, i.e., fruiting body number and actual population size. Population Viability Analysis (PVA revealed that delayed seed release tendency (higher fruiting body number was not synchronized with actual ground conditions (lower population size. PVA analysis based on actual population size indicated that both the available populations would vanish within 20 years. The mean time of extinction calculated from both type census data indicated its extinction within 48 years. For assessing the conservation criteria, a glass house experiment was carried out with different soil types and compositions. Pure sand and higher proportions of sand -silt were more suitable compared to clay; further, gravelly surface was the most unsuitable habitat for this species. Collection of the seeds from mature fruits/capsule and their sowing with moderate moisture availability with sandy soil could be recommended.

  7. The origin of the attine ant-fungus mutualism.

    Science.gov (United States)

    Mueller, U G; Schultz, T R; Currie, C R; Adams, R M; Malloch, D

    2001-06-01

    Cultivation of fungus for food originated about 45-65 million years ago in the ancestor of fungus-growing ants (Formicidae, tribe Attini), representing an evolutionary transition from the life of a hunter-gatherer of arthropod prey, nectar, and other plant juices, to the life of a farmer subsisting on cultivated fungi. Seven hypotheses have been suggested for the origin of attine fungiculture, each differing with respect to the substrate used by the ancestral attine ants for fungal cultivation. Phylogenetic information on the cultivated fungi, in conjunction with information on the nesting biology of extant attine ants and their presumed closest relatives, reveal that the attine ancestors probably did not encounter their cultivars-to-be in seed stores (von Ihering 1894), in rotting wood (Forel 1902), as mycorrhizae (Garling 1979), on arthropod corpses (von Ihering 1894) or ant faeces in nest middens (Wheeler 1907). Rather, the attine ant-fungus mutualism probably arose from adventitious interactions with fungi that grew on walls of nests built in leaf litter (Emery 1899), or from a system of fungal myrmecochory in which specialized fungi relied on ants for dispersal (Bailey 1920) and in which the ants fortuitously vectored these fungi from parent to offspring nests prior to a true fungicultural stage. Reliance on fungi as a dominant food source has evolved only twice in ants: first in the attine ants, and second in some ant species in the solenopsidine genus Megalomyrmex that either coexist as trophic parasites in gardens of attine hosts or aggressively usurp gardens from them. All other known ant-fungus associations are either adventitious or have nonnutritional functions (e.g., strengthening of carton-walls in ant nests). There exist no unambiguous reports of facultative mycophagy in ants, but such trophic ant-fungus interactions would most likely occur underground or in leaf litter and thus escape easy observation. Indirect evidence of fungivory can be deduced

  8. Maximum mutual information regularized classification

    KAUST Repository

    Wang, Jim Jing-Yan

    2014-09-07

    In this paper, a novel pattern classification approach is proposed by regularizing the classifier learning to maximize mutual information between the classification response and the true class label. We argue that, with the learned classifier, the uncertainty of the true class label of a data sample should be reduced by knowing its classification response as much as possible. The reduced uncertainty is measured by the mutual information between the classification response and the true class label. To this end, when learning a linear classifier, we propose to maximize the mutual information between classification responses and true class labels of training samples, besides minimizing the classification error and reducing the classifier complexity. An objective function is constructed by modeling mutual information with entropy estimation, and it is optimized by a gradient descend method in an iterative algorithm. Experiments on two real world pattern classification problems show the significant improvements achieved by maximum mutual information regularization.

  9. Dispersão de sementes de Vismia cayennensis (Jacq. Pers. (Guttiferae por morcegos na região de Manaus, Amazonas Seed dispersal of Vismia cayennensis (Jacq. Pers (Guttiferae by bats in Manaus, Amazonas

    Directory of Open Access Journals (Sweden)

    Jader Marinho-Filho

    1994-07-01

    Full Text Available Estudou-se o comportamento alimentar de morcegos e o seu papel na dispersão de sementes de Vismia cayennensis na região de Manaus, Amazonas. As características da planta e dos frutos correspondem à síndrome de quiropterocoria. Cinco espécies de morcegos filostomídeos se alimentaram dos frutos: Sturnira lilium, Sturnira tildae, Artibeus concolor, Carollia perspicillata e Rhinophylla pumilio. Aparentemente, há uma relação entre o comportamento de forrageamento em grupos e a maior disponibilidade de frutos na primeira parte da noite. O comportamento alimentar foi semelhante para todas as espécies de morcegos, variando em função do modo de apresentação dos frutos. Os testes de germinação e os padrões de distribuição das plantas indicam que morcegos são os dispersores efetivos de V. cayennensis.We studied the feeding behavior of bats and their role in the seed dispersal of Vismia cayennensis in Manaus region, Amazonas State, northern Brazil. The characteristics of the plant and its fruits fit the chiropterocory syndrome. Five species of phyllostomid bats fed on Vismia fruits: Sturnira lilium, Sturnira tildae, Artibeus concolor, Carollia perspicillata and Rhinophylla pumilio. Apparently there is a relationship between flock foraging behavior and fruit availability in early night. The feeding behavior was similar for all bat species, varying with the presentation mode of the fruits. Seed germination tests and the distributional patterns of the plants indicate that bats are the dispersers of V. cayennensis.

  10. Dispersal and metapopulation stability

    Directory of Open Access Journals (Sweden)

    Shaopeng Wang

    2015-10-01

    Full Text Available Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability.

  11. Entanglement in mutually unbiased bases

    Energy Technology Data Exchange (ETDEWEB)

    Wiesniak, M; Zeilinger, A [Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Paterek, T, E-mail: tomasz.paterek@nus.edu.sg [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore (Singapore)

    2011-05-15

    One of the essential features of quantum mechanics is that most pairs of observables cannot be measured simultaneously. This phenomenon manifests itself most strongly when observables are related to mutually unbiased bases. In this paper, we shed some light on the connection between mutually unbiased bases and another essential feature of quantum mechanics, quantum entanglement. It is shown that a complete set of mutually unbiased bases of a bipartite system contains a fixed amount of entanglement, independent of the choice of the set. This has implications for entanglement distribution among the states of a complete set. In prime-squared dimensions we present an explicit experiment-friendly construction of a complete set with a particularly simple entanglement distribution. Finally, we describe the basic properties of mutually unbiased bases composed of product states only. The constructions are illustrated with explicit examples in low dimensions. We believe that the properties of entanglement in mutually unbiased bases may be one of the ingredients to be taken into account to settle the question of the existence of complete sets. We also expect that they will be relevant to applications of bases in the experimental realization of quantum protocols in higher-dimensional Hilbert spaces.

  12. Frugivory and seed dispersal of Miconia theaezans (Bonpl.) Cogniaux (Melastomataceae) by birds in a transition palm swamp: gallery forest in Central Brazil.

    Science.gov (United States)

    Borges, M R; Melo, C

    2012-02-01

    The objective of this study was to evaluate potential avian dispersers of Miconia theaezans by dietary habits in the Cerrado of Central Brazil. Forty-two hours and 40 minutes of focal tree observation were conducted between 7:00 AM and 5:00 PM. For each bird species that consumed the fruit, we registered: the time they remained on the plant, the total amount of fruit they consumed, foraging tactics and strategies to consume the fruit. Five-hundred and fifty-nine units of fruit were consumed in 47 visits by seven bird species. Thraupidae was the most frequent and representative family and Tangara cayana was the main consumer. The Tachyphonus rufus had the highest rate of intake of the entire fruit, however the rates were not significantly different among the visitors. The most-used foraging tactic by all species was to consume the fruit while "perched" (95.74% of the visits). The most commonly-used consumption strategy was to mandibulate the fruit and swallow all the contents (65.12%). Omnivores were the predominant visitors (71.43%) and made most of the visits (89.36%). All visiting species could act as potential dispersers of M. theaezans, which demonstrates the low selectiveness of this pioneer plant towards its frugivorous.

  13. Mutualism Disruption Threatens Global Plant Biodiversity: A Systematic Review.

    Directory of Open Access Journals (Sweden)

    Clare E Aslan

    Full Text Available As global environmental change accelerates, biodiversity losses can disrupt interspecific interactions. Extinctions of mutualist partners can create "widow" species, which may face reduced ecological fitness. Hypothetically, such mutualism disruptions could have cascading effects on biodiversity by causing additional species coextinctions. However, the scope of this problem - the magnitude of biodiversity that may lose mutualist partners and the consequences of these losses - remains unknown.We conducted a systematic review and synthesis of data from a broad range of sources to estimate the threat posed by vertebrate extinctions to the global biodiversity of vertebrate-dispersed and -pollinated plants. Though enormous research gaps persist, our analysis identified Africa, Asia, the Caribbean, and global oceanic islands as geographic regions at particular risk of disruption of these mutualisms; within these regions, percentages of plant species likely affected range from 2.1-4.5%. Widowed plants are likely to experience reproductive declines of 40-58%, potentially threatening their persistence in the context of other global change stresses.Our systematic approach demonstrates that thousands of species may be impacted by disruption in one class of mutualisms, but extinctions will likely disrupt other mutualisms, as well. Although uncertainty is high, there is evidence that mutualism disruption directly threatens significant biodiversity in some geographic regions. Conservation measures with explicit focus on mutualistic functions could be necessary to bolster populations of widowed species and maintain ecosystem functions.

  14. Can dispersal investment explain why tall plant species achieve longer dispersal distances than short plant species?

    Science.gov (United States)

    Thomson, Fiona J; Letten, Andrew D; Tamme, Riin; Edwards, Will; Moles, Angela T

    2018-01-01

    Tall plant species disperse further distances than do short species, within and across dispersal syndromes, yet the driver underpinning this relationship is unclear. The ability of taller plants to invest more in dispersal structures may explain the positive relationship between plant height and dispersal distance. Here, we quantify the cross-species relationships between presence of dispersal structures, dispersal investment plant height and dispersal distance. Plant height, dispersal syndrome and dispersal investment data were collated for 1613 species from the literature, with dispersal distance data collated for 114 species. We find that species with high dispersal investment disperse further than do species with low dispersal investment. Tall species have a greater probability of having dispersal structures on their seeds compared with short species. For species with dispersal structures on their seeds, plant height is very weakly related to dispersal investment. Our results provide the first global confirmation of the dispersal investment-distance hypothesis, and show dispersal investment can be used for predicting species dispersal distances. However, our results and those of previous studies indicate plant height is still the best proxy for estimating species dispersal distances due to it being such a readily available plant trait. © 2017 Landcare Research. New Phytologist © 2017 New Phytologist Trust.

  15. Seed dormancy and germination : light and nitrate

    NARCIS (Netherlands)

    Hilhorst, H.W.M.

    1990-01-01

    One of the most important aspects of the life cycle of seed plants is the formation and development of seeds on the motherplant and the subsequent dispersal. An equally important element of the survival strategy is the ability of seeds to prevent germination in unfavorable

  16. Aspects of the seed ecology of Acacia karroo in the Eastern Cape ...

    African Journals Online (AJOL)

    Cattle were confirmed as dispersal agents. Using experimental seed banks, it was shown that buried or surface-exposed seeds did not persist for longer than a year, but 24% of surface-shaded seeds persisted for two years. Most seeds germinated but most buried seeds died before emergence. Seed persistence in deep ...

  17. Seed quality in informal seed systems

    NARCIS (Netherlands)

    Biemond, P.C.

    2013-01-01

    Keywords:     informal seed systems, seed recycling, seed quality, germination, seed pathology, seed health, seed-borne diseases, mycotoxigenic fungi, Fusarium verticillioides, mycotoxins, Vigna unguiculata, Zea mays, Nigeria.   Seed is a crucial input for agricultural

  18. Seed dormancy and germination.

    Science.gov (United States)

    Penfield, Steven

    2017-09-11

    Reproduction is a critical time in plant life history. Therefore, genes affecting seed dormancy and germination are among those under strongest selection in natural plant populations. Germination terminates seed dispersal and thus influences the location and timing of plant growth. After seed shedding, germination can be prevented by a property known as seed dormancy. In practise, seeds are rarely either dormant or non-dormant, but seeds whose dormancy-inducing pathways are activated to higher levels will germinate in an ever-narrower range of environments. Thus, measurements of dormancy must always be accompanied by analysis of environmental contexts in which phenotypes or behaviours are described. At its simplest, dormancy can be imposed by the formation of a simple physical barrier around the seed through which gas exchange and the passage of water are prevented. Seeds featuring this so-called 'physical dormancy' often require either scarification or passage through an animal gut (replete with its associated digestive enzymes) to disrupt the barrier and permit germination. In other types of seeds with 'morphological dormancy' the embryo remains under-developed at maturity and a dormant phase exists as the embryo continues its growth post-shedding, eventually breaking through the surrounding tissues. By far, the majority of seeds exhibit 'physiological dormancy' - a quiescence program initiated by either the embryo or the surrounding endosperm tissues. Physiological dormancy uses germination-inhibiting hormones to prevent germination in the absence of the specific environmental triggers that promote germination. During and after germination, early seedling growth is supported by catabolism of stored reserves of protein, oil or starch accumulated during seed maturation. These reserves support cell expansion, chloroplast development and root growth until photoauxotrophic growth can be resumed. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  19. Mutual Recogniton of Professional Qualifications

    DEFF Research Database (Denmark)

    Enemark, Stig; Plimmer, Francis

    The publication aims to review the concept of mutual recognition of qualifications within the world wide surveying community, and to develop a framework for the introduction of standards of global professional competence in this area. The publication also includes a number of case studies from...

  20. The evolution of mutual ornamentation

    NARCIS (Netherlands)

    Kraaijeveld, Ken; Kraaijeveld-Smit, Femmie J. L.; Komdeur, Jan

    2007-01-01

    Many conspicuous ornamental traits in animals are expressed in both males and females. Despite this, most research has focused on sexually dimorphic ornamentation. Mutual ornamentation has often been viewed as a result of either a nonadaptive genetic correlation between the sexes or similar

  1. Dispersal limitation induces long-term biomass collapse in overhunted Amazonian forests.

    Science.gov (United States)

    Peres, Carlos A; Emilio, Thaise; Schietti, Juliana; Desmoulière, Sylvain J M; Levi, Taal

    2016-01-26

    Tropical forests are the global cornerstone of biological diversity, and store 55% of the forest carbon stock globally, yet sustained provisioning of these forest ecosystem services may be threatened by hunting-induced extinctions of plant-animal mutualisms that maintain long-term forest dynamics. Large-bodied Atelinae primates and tapirs in particular offer nonredundant seed-dispersal services for many large-seeded Neotropical tree species, which on average have higher wood density than smaller-seeded and wind-dispersed trees. We used field data and models to project the spatial impact of hunting on large primates by ∼ 1 million rural households throughout the Brazilian Amazon. We then used a unique baseline dataset on 2,345 1-ha tree plots arrayed across the Brazilian Amazon to model changes in aboveground forest biomass under different scenarios of hunting-induced large-bodied frugivore extirpation. We project that defaunation of the most harvest-sensitive species will lead to losses in aboveground biomass of between 2.5-5.8% on average, with some losses as high as 26.5-37.8%. These findings highlight an urgent need to manage the sustainability of game hunting in both protected and unprotected tropical forests, and place full biodiversity integrity, including populations of large frugivorous vertebrates, firmly in the agenda of reducing emissions from deforestation and forest degradation (REDD+) programs.

  2. Seed maturation in Arabidopsis thaliana is characterized by nuclear size reduction and increased chromatin condensation

    NARCIS (Netherlands)

    van Zanten, M.; Koini, M. A.; Geyer, R.; Liu, Y.; Brambilla, V.; Bartels, D.; Koornneef, M.; Fransz, P.; Soppe, W. J.

    2011-01-01

    Most plant species rely on seeds for their dispersal and survival under unfavorable environmental conditions. Seeds are characterized by their low moisture content and significantly reduced metabolic activities. During the maturation phase, seeds accumulate storage reserves and become

  3. Seed maturation in Arabidopsis is characterised by nuclear size reduction and increased chromatin condensation

    NARCIS (Netherlands)

    Zanten, van M.; Koini, M.A.; Geyer, R.; Liu, Y.; Brambilla, V.; Bartels, D.; Koornneef, M.; Fransz, P.; Soppe, W.J.J.

    2011-01-01

    Most plant species rely on seeds for their dispersal and survival under unfavorable environmental conditions. Seeds are characterized by their low moisture content and significantly reduced metabolic activities. During the maturation phase, seeds accumulate storage reserves and become

  4. Did fleshy fruit pulp evolve as a defence against seed loss rather ...

    Indian Academy of Sciences (India)

    120 218–241. Herrera C M 1984a Determinants of plant-animal coevolution: the case of mutualistic dispersal of seeds by vertebrates; Oikos 44 132–141. Herrera C M 1984b Adaptation to frugivory of. Mediterranean avian seed dispersers; Ecology 65 609–. 617. Herrera C M 1989a Seed dispersal by animals: a role in.

  5. Mutual funds: temporary problem or permanent morass?

    OpenAIRE

    Paula A. Tkac

    2004-01-01

    The improprieties in the mutual fund industry that surfaced in the fall of 2003 prompted the passage and drafting of legislation and regulations that cover nearly every facet of mutual fund pricing and operations. While this regulatory flurry is clearly intended to protect shareholders’ interests, the question remains: How will these scandals and regulatory changes ultimately affect mutual fund investors? ; When considering the problems inherent in mutual fund management and the best ways to ...

  6. Secondary seed dispersal of Ricinus communis Linnaeus (Euphorbiaceae by ants in secondary growth vegetation in Minas Gerais Dispersão secundária de sementes de Ricinus communis Linnaeus (Euphorbiaceae por formigas em vegetação secundária em Minas Gerais

    Directory of Open Access Journals (Sweden)

    Mário Marcos do Espírito Santo

    2007-12-01

    Full Text Available In this study, I tested the efficacy of ants as secondary seed dispersers of Ricinus communis in southeastern Brazil. In a natural population of 143 individuals, I determined the ballistic dispersal distance for 62 seeds and 100 additional seeds were experimentally offered to ants in groups of ten seeds along a transect of 50 m. Fifty-three seeds were removed by ants, mainly by the leafcutter Atta sexdens (90.4%. The dispersal distance by ants was high, compared to the global average (4.38 m ± 0.74 m vs. 0.96 m, but was lower than the ballistic distance (7.27 m ± 0.13 m. Ants increased the total dispersal distance (8.66 m ± 0.60 m, but the main benefit for the plant was the directed dispersal, with seed deposition on the enriched soil of ant nests.Este estudo testou a eficiência de formigas como dispersores secundários de Ricinus communis no Brasil. Em uma população natural de 143 indivíduos, a distância de dispersão balística foi determinada para 62 sementes. Além disso, 100 sementes adicionais foram oferecidas a formigas em grupos de 10, ao longo de um transecto de 50 m. Cinqüenta e três sementes foram removidas por formigas, principalmente pela formiga-cortadeira Atta sexdens (90,4%. A distância de dispersão por formigas foi alta se comparada à média global (4,38m ± 0,74 m vs. 0,96 m, porém menor que a distância de dispersão balística (7,27 m ± 0,13 m. As formigas aumentaram a distância de dispersão total (8,66 m ± 0,60 m, mas o principal benefício para a planta foi a dispersão direcionada, com a deposição das sementes no solo enriquecido encontrado nos ninhos das formigas.

  7. Assessing ant seed predation in threatened plants: a case study

    Science.gov (United States)

    Albert, María José; Escudero, Adrián; Iriondo, José María

    2005-11-01

    Erodium paularense is a threatened plant species that is subject to seed predation by the granivorous ant Messor capitatus. In this paper we assessed the intensity and pattern of ant seed predation and looked for possible adaptive strategies at the seed and plant levels to cope with this predation. Seed predation was estimated in 1997 and 1998 at the population level by comparing total seed production and ant consumption, assessed by counting seed hulls in refuse piles. According to this method, ant seed predation ranged between 18% and 28%. A more detailed and direct assessment conducted in 1997 raised this estimate to 43%. In this assessment spatial and temporal patterns of seed predation by ants were studied by mapping all nest entrances in the studied area and marking the mature fruits of 109 reproductive plants with a specific colour code throughout the seed dispersal period. Intact fruit coats were later recovered from the refuse piles, and their mother plants and time of dispersal were identified. Seeds dispersed at the end of the dispersal period had a greater probability of escaping from ant seed predation. Similarly, in plants with late dispersal a greater percentage of seeds escaped from ant predation. Optimum dispersal time coincided with the maximum activity of granivorous ants because, at this time, ants focused their harvest on other plant species of the community. It was also observed that within-individual seed dispersal asynchrony minimised seed predation. From a conservation perspective, results show that the granivorous ant-plant interaction cannot be assessed in isolation and that the intensity of its effects basically depends on the seed dispersal pattern of the other members of the plant community. Furthermore, this threat must be assessed by considering the overall situation of the target population. Thus, in E. paularense, the strong limitation of safe-sites for seedling establishment reduces the importance of seed predation.

  8. Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms

    Directory of Open Access Journals (Sweden)

    Christopher A. Loebach

    2018-03-01

    Full Text Available Introduction Alliaria petiolata, an herbaceous plant, has invaded woodlands in North America. Its ecology has been thoroughly studied, but an overlooked aspect of its biology is seed dispersal distances and mechanisms. We measured seed dispersal distances in the field and tested if epizoochory is a potential mechanism for long-distance seed dispersal. Methods Dispersal distances were measured by placing seed traps in a sector design around three seed point sources, which consisted of 15 second-year plants transplanted within a 0.25 m radius circle. Traps were placed at intervals ranging from 0.25–3.25 m from the point source. Traps remained in the field until a majority of seeds were dispersed. Eight probability density functions were fitted to seed trap counts via maximum likelihood. Epizoochory was tested as a potential seed dispersal mechanism for A. petiolata through a combination of field and laboratory experiments. To test if small mammals transport A. petiolata seeds in their fur, experimental blocks were placed around dense A. petiolata patches. Each block contained a mammal inclusion treatment (MIT and control. The MIT consisted of a wood-frame (31 × 61× 31 cm covered in wire mesh, except for the two 31 × 31 cm ends, placed over a germination tray filled with potting soil. A pan filled with bait was placed in the center of the tray. The control frame (11 × 31 × 61 cm was placed over a germination tray and completely covered in wire mesh to exclude animal activity. Treatments were in the field for peak seed dispersal. In March, trays were moved to a greenhouse and A. petiolata seedlings were counted and then compared between treatments. To determine if A. petiolata seeds attach to raccoon (Procyon lotor and white-tailed deer (Odocoileus virginianus fur, wet and dry seeds were dropped onto wet and dry fur. Furs were rotated 180 degrees and the seeds that remained attached were counted. To measure seed retention, seeds

  9. Mutual benefit societies in Colombia

    Directory of Open Access Journals (Sweden)

    Beatriz Castro C.

    2002-01-01

    Full Text Available The article describes the creation and spreading of the diverse congregations whose main purpose was to maintain solidarity among their members. Often these were called mutual benefit companies, during the middle of the XIX century and half of the XX century. These societies embraced handicrafters and small merchants who identified themselves with Christian tradition values. It is easy to observe in them the legate of the colonial confraternity, artisan associations and democratic societies which somehow were an evolution of the European spiritual confraternities of the middle ages.

  10. Dispersal of seeds of Hymenaea courbaril (Fabaceae in a logged rain forest in the Peruvian Amazonian Dispersão de sementes de Hymenaea courbaril (Fabaceae em uma floresta tropical úmida com exploração madeireira na Amazônia peruana

    Directory of Open Access Journals (Sweden)

    David L. Gorchov

    2004-01-01

    Full Text Available Seed dispersal of Hymenaea courbaril was studied by following the fate of 585 seeds embedded with small magnets and set in displays in and near a logged strip in rain forest in the Peruvian Amazonian. Mammals took fruits from all displays, which were located in the forest, edge, and cleared strip. Overall removal rates were low - a median of 8.1 fruits / month from displays maintained with 8-10 fruits - but were higher in August than in earlier months. Most fruits were dropped near the display or had their seeds eaten, but > 13% were successfully dispersed. Most of the dispersed seeds were buried, which increases probability of germination. Maximum dispersal distance of live seeds was 12.1 m (median 3.1 m, but other magnets were transported up to 34 m, indicating seeds were dispersed further, but then eaten. Acouchies (most likely Myoprocta pratti and agoutis (Dasyprocta fuliginosa were apparently the main dispersal agents. Dispersal of seeds from the forest into the logged strip was rare, suggesting that although rodents disperse H. courbaril, they cannot be relied on for the reseeding this and similar species in recent clearings.Foi estudada a dispersão de sementes de Hymenaea courbaril, seguindo o destino de 585 sementes marcadas com imãs e expostas a potenciais dispersores, colocadas em agregados no interior e próximo de uma faixa de floresta cortada, na Amazónia peruana. Mamíferos retiraram frutos de todos os agregados, localizados no interior da floresta, na sua borda, e na clareira. As taxas de remoção foram baixas - mediana de 8.1 frutos/mês em agregados mantidos com 8-10 frutos - mas foram mais altas em agosto que nos primeiros meses do ano. A maior parte dos frutos foi abandonada próxima do agregado de origem ou as suas sementes foram consumidas, mas > 13% foram dispersos com sucesso. A maior parte das sementes dispersas foi enterrada, o que favorece a germinação. A distância máxima de dispersão de sementes vivas foi de

  11. Burial increases seed longevity of two Artemisia tridentata (Asteraceae) subspecies.

    Science.gov (United States)

    Wijayratne, Upekala C; Pyke, David A

    2012-03-01

    Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active role in postfire recovery of the foundation shrub Artemisia tridentata, yet conditions under which seeds persist are largely unknown. We investigated seed longevity of two Artemisia tridentata subspecies in situ by retrieving seed bags that were placed at varying depths over a 2 yr period. We also sampled naturally dispersed seeds in litter and soil immediately after seed dispersal and before flowering in subsequent seasons to estimate seed persistence. After 24 mo, seeds buried at least 3 cm below the soil surface retained 30-40% viability whereas viability of seeds on the surface and under litter declined to 0 and seeds in the seed bank was highly heterogeneous both spatially and temporally, and attrition varied significantly by region. Our study suggests that Artemisia tridentata has the potential to form a short-term soil seed bank that persists longer than has been commonly assumed, and that burial is necessary for seed longevity. Use of seeding techniques that promote burial of some seeds to aid in formation of a soil seed bank may increase restoration potential.

  12. Small-mammal seed predation limits the recruitment and abundance of two perennial grassland forbs

    Science.gov (United States)

    Mary Bricker; Dean Pearson; John Maron

    2010-01-01

    Although post-dispersal seed predators are common and often reduce seed density, their influence on plant population abundance remains unclear. On the one hand, increasing evidence suggests that many plant populations are seed limited, implying that seed predators could reduce plant abundance. On the other hand, it is generally uncertain whether the magnitude of seed...

  13. Diamond Synthesis Employing Nanoparticle Seeds

    Science.gov (United States)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  14. Mutualism and impacts of global change: response of an important and neglected component of the biodiversity

    International Nuclear Information System (INIS)

    Hossaert-Mckey, M.

    2007-01-01

    We are studying the impact of global change on two obligate species-specific insect-plant mutualisms. Our approach combines correlative methods (examining spatial patterns of genetic diversity in populations of pairs of mutualists, to examine their responses to past climate change) and experiments (studying responses of plant partners to CO 2 fertilization). Mutualisms function because the partners have contrasting and complementary biological traits, so that a service implying only a low cost to one partner may confer a great benefit to the other. Because they can lead mutualist partners to respond differently to rapid ecological change, the biological differences that are fundamental to mutualisms may also make them vulnerable. Imbalances thereby introduced can disrupt the functioning of the mutualism. By comparing two strongly contrasting systems-fig/wasp pollination mutualisms and ant-plant protection mutualisms-we aim to characterize the diversity of responses of mutualisms to global change. By identifying points in common, we also aim to propose robust generalizations about the response to global change of obligate, specific mutualisms, an important and neglected component of tropical biodiversity. Our results show that the two mutualisms studied differ greatly in their response to Pleistocene and Holocene climatic fluctuations. Fig/wasp systems show little spatial genetic differentiation, indicating that the great dispersal capacities of both figs and their pollinating wasps resulted in maintenance of high effective population sizes throughout cycles of climatic and vegetation change. In contrast, limited dispersal capacity of both ant and plant partners has resulted in greater impact of climatic fluctuations on ant/plant protection mutualisms: species-distribution patterns suggest restriction of the system to refugia, and strong spatial genetic structure indicates widespread bottlenecks during fragmentation and expansion. Alternate contraction and expansion

  15. Dispersión de semillas por aves en un paisaje de bosque mesófilo en el centro de Veracruz, México: Su papel en la restauración pasiva Seed dispersal by birds in a cloud forest landscape in central Veracruz, Mexico: Its role in passive restoration

    Directory of Open Access Journals (Sweden)

    IVETTE HERNÁNDEZ-LADRÓN DE GUEVARA

    2012-03-01

    las especies de semillas encontradas, el 59 % germinó en las excretas del 78 % de las especies de aves. Este trabajo muestra que en los bosques mesófilos de montaña las aves son agentes dispersores importantes de especies de plantas pertenecientes a bosques secundarios y también dispersores de algunas plantas del bosque primario, por ello son agentes que facilitan el proceso de sucesión forestal.Seed dispersal by birds may play a major role in the successful natural forest restoration process as birds can deposit pioneer and primary seeds species, thereby defining the recovery of plant community composition over time. In this study, seed ingestion and dispersion by frugivorous birds were analyzed as processes facilitating the restoration of tropical cloud montane forests in central Veracruz, Mexico. Birds were classified according to their affinity to the forest and their preference to a particular forest stratum, in order to determine whether these factors were related to the richness, abundance and diversity of ingested and dispersed seeds. We analyzed 93 fecal samples from 23 bird species. A total of 2699 seeds from 17 plant species were found in the fecal samples, the most abundant seed was from the shrub Conostegia xalapensis. We analyzed the correlation between seed size and beak size for the six most frequently captured bird species. We also evaluated the effect of bird ingestion on seed germination by performing two experiments, the first one using the total number of seeds found in fecal samples, and the second one using C. xalapensis seeds that were administered artificially to the birds and their germination compared with control seeds. We found significant differences among the ingested seed diversity indexes for the most commonly captured birds, which supports a differential seed consumption and dispersion. However, there were no significant differences of the seed abundance and richness between birds with different forest affinity or forest stratum

  16. Fragmentation and seed dispersal in freshwater wetlands

    NARCIS (Netherlands)

    Soomers, H.

    2012-01-01

    Human impact on nature has been severe in the past centuries. Land use change is seen as the main driver of the loss of biodiversity worldwide. Conversion of natural ecosystems into agricultural land or urban areas has led to habitat loss and degradation for many plant species. Additionally, land

  17. Tracking Seed Fates of Tropical Tree Species: Evidence for Seed Caching in a Tropical Forest in North-East India

    Science.gov (United States)

    Sidhu, Swati; Datta, Aparajita

    2015-01-01

    Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket, Brachytrupes sp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% in Beilschmiedia assamica to 97% in Actinodaphne obovata. Seed predation was observed in nine species. Chisocheton cumingianus (57%) and Prunus ceylanica (25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p seed size. Removal rates were significantly

  18. Empirical study on mutual fund objective classification.

    Science.gov (United States)

    Jin, Xue-jun; Yang, Xiao-lan

    2004-05-01

    Mutual funds are usually classified on the basis of their objectives. If the activities of mutual funds are consistent with their stated objectives, investors may look at the latter as signals of their risks and incomes. This work analyzes mutual fund objective classification in China by statistical methods of distance analysis and discriminant analysis; and examines whether the stated investment objectives of mutual funds adequately represent their attributes to investors. That is, if mutual funds adhere to their stated objectives, attributes must be heterogeneous between investment objective groups and homogeneous within them. Our conclusion is to some degree, the group of optimized exponential funds is heterogeneous to other groups. As a whole, there exist no significant differences between different objective groups; and 50% of mutual funds are not consistent with their objective groups.

  19. Seed quality in informal seed systems

    OpenAIRE

    Biemond, P.C.

    2013-01-01

    Keywords:     informal seed systems, seed recycling, seed quality, germination, seed pathology, seed health, seed-borne diseases, mycotoxigenic fungi, Fusarium verticillioides, mycotoxins, Vigna unguiculata, Zea mays, Nigeria.   Seed is a crucial input for agricultural production. Approximately 80% of the smallholder farmers in Africa depend for their seed on the informal seed system, consisting of farmers involved in selection, production and dissemination of seed. The la...

  20. Dieta e dispersão de sementes por Cerdocyon thous (Linnaeus (Carnívora, Canidae, em um fragmento florestal no Paraná, Brasil Diet and seed dispersal by Cerdocyon thous (Linnaeus in a forest fragment in Paraná (Carnivora, Canidae

    Directory of Open Access Journals (Sweden)

    Vlamir J. Rocha

    2004-12-01

    Full Text Available Embora o cachorro-do-mato, Cerdocyon thous (Linnaeus, 1706, seja um Canidae relativamente comum, não há muita informação sobre sua dieta e seu papel como dispersor de sementes nos diferentes habitats onde ocorre. O objetivo deste trabalho foi o de reportar a dieta de C. thous e sua importância como dispersor e/ou predador de sementes, e ainda testar a taxa de germinação de sementes após passar pelo trato digestório do animal. O estudo foi realizado em um fragmento (680 ha de Floresta Estacional Semidecidual, o Parque Estadual Mata dos Godoy, localizado na cidade de Londrina, Paraná, sul do Brasil. A metodologia consistiu de coletas de fezes de C. thous, as quais foram analisadas em laboratório para identificar os itens consumidos. Nos testes de germinação, as sementes foram dispostas para germinar em placas de Petri com algodão umedecido em água. Noventa e três amostras fecais com 219 itens de origem vegetal e animal foram registradas, sendo 36,52% contendo restos de pequenos roedores, 24,19% de gramíneas, 13,24% de aves, 10,47% de insetos, 6,39% de Syagrus romanzoffiana (Cham. Glassm., 4,6% de outros itens de origem animal e 4,54% de outros itens de origem vegetal. Ainda, C. thous dispersou nove espécies de plantas, com relevante importância para a germinação de algumas sementes que passaram pelo trato digestório do animal, exceto para S. romanzoffiana, cujas sementes não germinaram nas condições de laboratório. Conclui-se que, C. thous apresentou uma dieta generalista e oportunista, sobrevivendo em áreas degradadas e antrópicas, e agindo como dispersor de sementes nestes locais.Although the crab eating fox, Cerdocyon thous (Linnaeus, 1706, is a relatively common Canidae, there isn't much information about its diet and its role as a seed disperser in the different habitats where it occurs. The aim of this work was to report the diet of the C. thous and its importance as a seed disperser and / or a seed predator and

  1. Hydrodynamic disperser

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, A.I.; Chernov, V.S.; Prokopov, L.I.; Proselkov, Yu.M.; Tikhonov, Yu.P.

    1980-01-15

    A hydrodynamic disperser is suggested which contains a housing, slit nozzles installed on a circular base arranged opposite from each other, resonators secured opposite the nozzle and outlet sleeve. In order to improve the effectiveness of dispersion by throttling the flow, each resonator is made in the form of a crimped plate with crimpings that decrease in height in a direction towards the nozzle.

  2. Seed quality in informal seed systems

    NARCIS (Netherlands)

    Biemond, P.C.

    2013-01-01

    Keywords: informal seed systems, seed recycling, seed quality, germination, seed pathology, seed health, seed-borne diseases, mycotoxigenic fungi, Fusarium verticillioides, mycotoxins, Vigna unguiculata, Zea mays, Nigeria.

    Seed is a crucial input for agricultural production.

  3. Darwin's wind hypothesis : does it work for plant dispersal in fragmented habitats?

    NARCIS (Netherlands)

    Riba, Miquel; Mayol, Maria; Giles, Barbara E.; Ronce, Ophelie; Imbert, Eric; van der Velde, Marco; Chauvet, Stephanie; Ericson, Lars; Bijlsma, R.; Vosman, Ben; Smulders, M. J. M.; Olivieri, Isabelle

    2009-01-01

    P>Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. Inverse terminal velocity (V(t)(-1)) of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to

  4. Darwin's wind hypothesis: does it work for plant dispersal in fragmented habitats?

    NARCIS (Netherlands)

    Riba, M.; Mayol, M.; Giles, B.E.; Ronce, O.; Imbert, E.; Velde, van der M.; Chauvet, S.; Ericson, L.; Bijlsma, R.; Vosman, B.; Smulders, M.J.M.; Olivieri, I.

    2009-01-01

    • Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. • Inverse terminal velocity (V(t)¯¹) of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to

  5. Strategy as Mutually Contingent Choice

    Directory of Open Access Journals (Sweden)

    Neil Martin

    2016-05-01

    Full Text Available Thomas Schelling’s The Strategy of Conflict carries significant behavioral implications which have been overlooked by economic readers. I argue that these implications are central to Schelling’s vision of game theory, that they fit well with recent advances in experimental psychology and behavioral economics, and provide a comprehensive framework that can inform research on strategy. In my view, Schelling develops a non-mathematical approach to strategy which anticipates on Gigerenzer and Selten’s “ecological rationality” program. This approach maps the processes involved in strategic reasoning and highlights their reliance on the particular information structure of interactive social environments. Building on this approach, I model strategy as a heuristic form of reasoning that governs the way in which individuals search for and provide cues in situations of mutually contingent choice. I conclude by examining how the reference to ecological rationality can help clarify Schelling’s contribution to game theory and outline potential avenues of research into strategic reasoning and interaction.

  6. Maximum auto-mutual-information factor analysis

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg

    2017-01-01

    Based on the information theoretical measure mutual information derived from entropy and Kullback-Leibler divergence, an alternative to maximum autocorrelation factor analysis is sketched.......Based on the information theoretical measure mutual information derived from entropy and Kullback-Leibler divergence, an alternative to maximum autocorrelation factor analysis is sketched....

  7. Economic contract theory tests models of mutualism.

    Science.gov (United States)

    Weyl, E Glen; Frederickson, Megan E; Yu, Douglas W; Pierce, Naomi E

    2010-09-07

    Although mutualisms are common in all ecological communities and have played key roles in the diversification of life, our current understanding of the evolution of cooperation applies mostly to social behavior within a species. A central question is whether mutualisms persist because hosts have evolved costly punishment of cheaters. Here, we use the economic theory of employment contracts to formulate and distinguish between two mechanisms that have been proposed to prevent cheating in host-symbiont mutualisms, partner fidelity feedback (PFF) and host sanctions (HS). Under PFF, positive feedback between host fitness and symbiont fitness is sufficient to prevent cheating; in contrast, HS posits the necessity of costly punishment to maintain mutualism. A coevolutionary model of mutualism finds that HS are unlikely to evolve de novo, and published data on legume-rhizobia and yucca-moth mutualisms are consistent with PFF and not with HS. Thus, in systems considered to be textbook cases of HS, we find poor support for the theory that hosts have evolved to punish cheating symbionts; instead, we show that even horizontally transmitted mutualisms can be stabilized via PFF. PFF theory may place previously underappreciated constraints on the evolution of mutualism and explain why punishment is far from ubiquitous in nature.

  8. Dispersal in Mastomys natalensis mice

    DEFF Research Database (Denmark)

    Van Hooft, Pim; Cosson, J F; Vibe-Petersen, Solveig

    2008-01-01

    genotyped. Genetic diversity was high, with no isolation by distance and little differentiation between field plots far apart, indicating a large effective population size and high dispersal rates in agreement with ecological observations. On the other hand, genetic differentiation between nearby field...... plots, isolation by distance within a single field plot and kin clustering were also observed. This apparent contradiction may be explained by yearly founder effects of a small number of breeding individuals per square area, which is consistent with the presence of linkage disequilibrium. An alternative......, not mutually exclusive explanation is that there are both dispersing and sedentary animals in the population. The low-density field plots were characterized by low relatedness and small genetic distances to other field plots, indicating a high turnover rate and negative density-dependent dispersal. In one...

  9. Evolutionary stability of mutualism: interspecific population regulation as an evolutionarily stable strategy

    Science.gov (United States)

    Holland, J. Nathaniel; DeAngelis, Donald L.; Schultz, Stewart T.

    2004-01-01

    Interspecific mutualisms are often vulnerable to instability because low benefit : cost ratios can rapidly lead to extinction or to the conversion of mutualism to parasite–host or predator–prey interactions. We hypothesize that the evolutionary stability of mutualism can depend on how benefits and costs to one mutualist vary with the population density of its partner, and that stability can be maintained if a mutualist can influence demographic rates and regulate the population density of its partner. We test this hypothesis in a model of mutualism with key features of senita cactus (Pachycereus schottii) – senita moth (Upiga virescens) interactions, in which benefits of pollination and costs of larval seed consumption to plant fitness depend on pollinator density. We show that plants can maximize their fitness by allocating resources to the production of excess flowers at the expense of fruit. Fruit abortion resulting from excess flower production reduces pre–adult survival of the pollinating seed–consumer, and maintains its density beneath a threshold that would destabilize the mutualism. Such a strategy of excess flower production and fruit abortion is convergent and evolutionarily stable against invasion by cheater plants that produce few flowers and abort few to no fruit. This novel mechanism of achieving evolutionarily stable mutualism, namely interspecific population regulation, is qualitatively different from other mechanisms invoking partner choice or selective rewards, and may be a general process that helps to preserve mutualistic interactions in nature.

  10. [Maintaining solidarity: is mutuality the solution?].

    Science.gov (United States)

    Gevers, J K M; Ploem, M C

    2013-01-01

    Solidarity is essentially the willingness to contribute to the community and its demands, which may even involve contributing more than one is expecting to receive. Another principle is mutuality: this refers to a balance between rights and obligations or between mutual obligations. In its advisory document 'The importance of mutuality......solidarity takes work!', The Dutch Council for Public Health and Health Care underlines the importance of ensuring solidarity within the Dutch health care system, e.g. by encouraging patients to take responsibility for their own health, possibly by introducing elements of mutuality. In our contribution, we comment on the Council's advice. Although we fully agree with the overall conclusion that solidarity should be maintained within the system, we do not see how the introduction of increased mutuality will contribute to this goal.

  11. Ants, rodents and seed predation in Proteaceae | Bond | African ...

    African Journals Online (AJOL)

    Results showed that seed prédation could be as high as 100%, but that ants usually discover and remove seeds before vertebrates. Significantly fewer seeds were dispersed by ants when elaiosomes were removed. Vertebrate removal rates also declined. Laboratory experiments with caged small mammals showed that ...

  12. Fruit Removal and Seed Predation in Two African Trees (Lannea ...

    African Journals Online (AJOL)

    Most L. welwitschii fruits were removed during and after maturation but predispersal seed predation by H. rufobrachium left only 19.9% of the total crop to potential seed dispersal. In contrast, H. rufobrachium rarely fed on L. acida seeds. Sun squirrels consumed about twice (L. acida) to 10 times as much (L. welwitschii) fruits ...

  13. Seed dynamics linked to variability in movement of tidal water

    NARCIS (Netherlands)

    Chang, E. R.; Veeneklaas, R. M.; Bakker, J. P.

    Question: Community structure may be influenced by patterns of dispersed seeds (seed rain) because they contribute to the template of plant community development. We explored factors influencing seed rain in a system dominated by tidal water, where direction and magnitude of water flow are difficult

  14. [Seed rain, soil seed bank, and natural regeneration of natural Toona ciliata var. pubescens forest].

    Science.gov (United States)

    Huang, Hong-Lan; Zhang, Lu; Liao, Cheng-Kai

    2012-04-01

    Taking the natural Toona ciliata var. pubescens forest in the Jiujiangshan National Nature Reserve in Jiangxi Province of China as test object, an investigation was conducted on the seed rain, soil seed bank, and seedlings number in 2008-2011. The seed rain of the forest was dispersed from late October to the end of December. In 2010, the seed rain intensity in different sampling plots was in the order of Xiagongtang observatory (320.3 +/- 23.5 seeds x m(-2)) > Xiagongtang protection station (284.7 +/- 24.2 seeds x m(-2)) > Daqiutian protection station (251.6 +/- 24.7 seeds x m(-2)), and the quantity of the intact seeds in soil supplied for seed germination and regeneration was 222.0, 34.3, and 22.6 seeds x m(-2), respectively. The seed bank reserves was affected by the seed production amount, bird feeding, and seed viability, etc., of which, bird feeding was the prime factor for the substantial drop of the seed bank reserves. Due to the low resistance against storage and a large number of rot during storage, the seeds in soil could hardly be effectively stored beyond one month. The seedlings germinated in December were averagely less than 2 stands x m(-2), and the soil seed reserves in the next January was the least (6.7-11.8 seeds x m(-2)), with the germinated seedlings averagely 0.4-0.6 stands x m(-2), which was consistent with the rare distribution of natural seedlings in the forest. It was concluded that the small seed rain reserves, low seed vigor of soil seed bank, and low seedling establishment were the important factors impacting the natural regeneration of T. ciliata var. pubescens.

  15. Patterns and mechanisms of dispersal in a keystone seagrass species

    DEFF Research Database (Denmark)

    Jahnke, M.; Christensen, Asbjørn; Micu, D.

    2016-01-01

    •Z. noltei shows low genetic connectivity (from 10 s to 100 s of km) in the Black Sea.•Physical modelling of dispersal well agree with estimates of genetic connectivity.•Physical and genetic connectivity show possible but rare long distance dispersal.•Seeds get dispersed locally while shoots have...

  16. Pathways of invasive plant spread to Alaska: III. contaminants in crop and grass seed

    Science.gov (United States)

    Invasive plants disperse to new areas via numerous pathways. Study of these pathways helps to focus limited budgets for prevention and early detection. This study examined seed contaminants in imported crop and grass seed as pathway for plant dispersal to Alaska. Crop and grass seed were purchased f...

  17. Humans as long-distance dispersers of rural plant communities.

    Directory of Open Access Journals (Sweden)

    Alistair G Auffret

    Full Text Available Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for species threatened by habitat destruction, but research into human-mediated dispersal is often focused upon few and/or invasive species. Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a known species pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in an alternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24,354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71 species (36% are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendages were more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted in more dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances were measured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities in which they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might have been regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscape may have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat and changes in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role of humans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance and regional dispersal, and international invasion.

  18. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  19. How much Dillenia indica seed predation occurs from Asian elephant dung?

    Science.gov (United States)

    Sekar, Nitin; Giam, Xingli; Sharma, Netra Prasad; Sukumar, Raman

    2016-01-01

    Elephants are thought to be effective seed dispersers, but research on whether elephant dung effectively protects seeds from seed predation is lacking. Quantifying rates of seed predation from elephant dung will facilitate comparisons between elephants and alternative dispersers, helping us understand the functional role of megaherbivores in ecosystems. We conducted an experiment to quantify the predation of Dillenia indica seeds from elephant dung in Buxa Reserve, India from December 2012 to April 2013. Using dung boluses from the same dung pile, we compared the number of seeds in boluses that are a) opened immediately upon detection (control boluses), b) made available only to small seed predators (seed predators and secondary dispersers for 1-4 months. Using a model built on this experiment, we estimated that seed predation by small seed predators (most likely ants and termites) destroys between 82.9% and 96.4% of seeds in elephant dung between the time of defecation and the median germination date for D. indica. Exposure to larger seed predators and secondary dispersers did not lead to a significant additional reduction in the number of seeds per dung bolus. Our findings suggest that post-dispersal seed predation by small insects (dispersers of D. indica in a tropical moist forest habitat.

  20. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction.

    Directory of Open Access Journals (Sweden)

    Ellen O Martinson

    Full Text Available A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association.

  1. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction.

    Science.gov (United States)

    Martinson, Ellen O; Hackett, Jeremiah D; Machado, Carlos A; Arnold, A Elizabeth

    2015-01-01

    A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association.

  2. Robotic seeding

    DEFF Research Database (Denmark)

    Pedersen, Søren Marcus; Fountas, Spyros; Sørensen, Claus Aage Grøn

    2017-01-01

    Agricultural robotics has received attention for approximately 20 years, but today there are only a few examples of the application of robots in agricultural practice. The lack of uptake may be (at least partly) because in many cases there is either no compelling economic benefit......, or there is a benefit but it is not recognized. The aim of this chapter is to quantify the economic benefits from the application of agricultural robots under a specific condition where such a benefit is assumed to exist, namely the case of early seeding and re-seeding in sugar beet. With some predefined assumptions...... with regard to speed, capacity and seed mapping, we found that among these two technical systems both early seeding with a small robot and re-seeding using a robot for a smaller part of the field appear to be financially viable solutions in sugar beet production....

  3. Seed size and provenance mediate the joint effects of disturbance and seed predation on community assembly

    Science.gov (United States)

    John L. Maron; Dean E. Pearson; Teal Potter; Yvette K. Ortega

    2012-01-01

    Local plant community assembly is influenced by a series of filters that affect the recruitment and establishment of species. These filters include regional factors that limit seeds of any given species from reaching a local site as well as local interactions such as post-dispersal seed predation and disturbance, which dictate what species actually establish. How these...

  4. Seed regulations and local seed systems

    NARCIS (Netherlands)

    Louwaars, N.

    2000-01-01

    Seed regulations have been introduced in most countries based on the development of formal seed production. Concerns about seed quality and about the varietal identity of the seeds have commonly led to seed laws. However, formal regulations are often inappropriate for informal seed systems, which

  5. Dispersion and current measurements

    International Nuclear Information System (INIS)

    Boelskifte, S.

    1986-04-01

    A model for the simulation of particle movements in water should incorporate the mutual distance dependent correlation. As long as reliable data are given accessible a model can be created of the dispersion in a given area from a statistical description of turbulence. Current measurements have been performed in an area north of the Swedish nuclear power plant Barsebaeck, and statistical time series analysis have made it possible to estimate multivariate autoregressive moving-average (ARMA) models for these data using the Box-Jenkins method. The correlation structure for the area has been investigated in detail. Transport and dispersion models for the marine environment are used in estimating doses to the population from the aquatic food chain. Some of these models are described with special emphasis on the time and length scales they cover. Furthermore, to illustrate the background of the simulation model, short introductuions are given to health physics, time series analysis, and turbulence theory. Analysis of the simulation model shows the relative importance of the different parameters. The model can be expanded to conditional simulation, where the current measurements are used directly to simulate the movement of one of the particles. Results from the model are also compared to results from a sampling of bioindicators (Fucus vesiculosus) along the Danish coast. The reliability of bioindicators in this kind of experiment is discussed. (author)

  6. Seed fate in the myrmecochorous Neotropical plant Turnera ulmifolia L., from plant to germination

    Science.gov (United States)

    Salazar-Rojas, Betzabeth; Rico-Gray, Víctor; Canto, Azucena; Cuautle, Mariana

    2012-04-01

    Myrmecochory (seed dispersal by ants) differs from other dispersal systems in a series of advantages offered by the ants to the plants. Here, seed fate, from fruit to germination, of the myrmecochorous Neotropical plant Turnera ulmifolia L. is described. Seed movement from the fruit to their germination was studied, using different measurements and experiments. The results show that a T. ulmifolia individual produces ca. 5000 seeds per year. The main pre-seed-fall predators are the larvae of the Microlepidopteran Crocidosema plebejana Zeller, which consumed 1% of the seeds on the plant. The red-land crab Gecarcinus lateralis (Freminville) consumed 19% of the seeds beneath the plant and was the main post-seed-fall predator. Seed removal by ants was recorded on and beneath the plant, and ants removed 49% of the total seed production. Considering the seed removal events, the ant Forelius analis contributed with 64% of the total number of events. F. analis took seeds to its nest and discarded 23% of the seeds collected. Germination of seeds collected by F. analis was two to four times higher than that of seeds with and without elaiosome, respectively. The relatively low seed predation was probably related to ant defense, associated with the presence of extrafloral nectaries in this plant and with seed removal on the plant. Our results suggest that F. analis is a quantitatively efficient but qualitatively inefficient seed disperser of T. ulmifolia.

  7. THE PERFORMANCE OF MUTUAL FUNDS IN SLOVAKIA

    Directory of Open Access Journals (Sweden)

    F. Tudorache

    2016-11-01

    Full Text Available A good indicator for the financial markets performance in different countries is the evolution of mutual funds in terms of their inflows and outflows. The goal of the present paper is to analyse the performance of the mutual funds in Slovakia. The research objectives are twofold: to study the flows of funds into and out of mutual funds from Slovakia during the period 2007-2014 and to analyse how investors in Slovakian mutual funds behave in terms of their investment choice. The analysis focuses on identifying patterns in investors' decision making process and on examining the similarity of their behavioural patterns with the ones identi¬fied at international level.

  8. Interactive effects between physical forces and ecosystem engineers on seed burial: a case study using

    NARCIS (Netherlands)

    Zhu, Z.; Cozzoli, F.; Chu, N.; Salvador, M.; Ysebaert, T.; Zhang, L.; Herman, P.M.J.; Bouma, T.J.

    2016-01-01

    Seed burial (i.e. vertical seed dispersal) has become increasingly valued for its relevance for seed fate and plant recruitment. While ecosystem engineers have been generally considered as the most important drivers of seed burial, the role of physical forces, such as wind or water flow, has been

  9. Downside Risk Timing by Mutual Funds

    OpenAIRE

    Bodnaruk, Andriy; Chokaev, Bekhan; Simonov, Andrei

    2015-01-01

    We study whether mutual funds systematically manage downside risk of their portfolios in ways that improve their performance. We find that actively managed mutual funds on average possess positive downside risk timing ability. Funds investing in large-cap and value stocks have stronger downside risk timing skills. Managers adjust funds’ downside risk exposure in response to macroeconomic information. The economic value of downside risk timing is comparable to that of market timing.

  10. Mutual Visibility by Robots with Persistent Memory

    OpenAIRE

    Bhagat, Subhash; Mukhopadhyaya, Krishnendu

    2017-01-01

    This paper addresses the mutual visibility problem for a set of semi-synchronous, opaque robots occupying distinct positions in the Euclidean plane. Since robots are opaque, if three robots lie on a line, the middle robot obstructs the visions of the two other robots. The mutual visibility problem asks the robots to coordinate their movements to form a configuration, within finite time and without collision, in which no three robots are collinear. Robots are endowed with a constant bits of pe...

  11. Morphological rates of angiosperm seed size evolution.

    Science.gov (United States)

    Sims, Hallie J

    2013-05-01

    The evolution of seed size among angiosperms reflects their ecological diversification in a complex fitness landscape of life-history strategies. The lineages that have evolved seeds beyond the upper and lower boundaries that defined nonflowering seed plants since the Paleozoic are more dispersed across the angiosperm phylogeny than would be expected under a neutral model of phenotypic evolution. Morphological rates of seed size evolution estimated for 40 clades based on 17,375 species ranged from 0.001 (Garryales) to 0.207 (Malvales). Comparative phylogenetic analysis indicated that morphological rates are not associated with the clade's seed size but are negatively correlated with the clade's position in the overall distribution of angiosperm seed sizes; clades with seed sizes closer to the angiosperm mean had significantly higher morphological rates than clades with extremely small or extremely large seeds. Likewise, per-clade taxonomic diversification rates are not associated with the seed size of the clade but with where the clade falls within the angiosperm seed size distribution. These results suggest that evolutionary rates (morphological and taxonomic) are elevated in densely occupied regions of the seed morphospace relative to lineages whose ecophenotypic innovations have moved them toward the edges. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  12. Removal of Nonmyrmecochorous Seeds by Ants: Role of Ants in Cattle Grasslands

    OpenAIRE

    Escobar-Ramírez, Selene; Duque, Sebastián; Henao, Natalia; Hurtado-Giraldo, Alejandra; Armbrecht, Inge

    2012-01-01

    Livestock production models prevailing in Colombian Andes are simplified treeless pastures for extensive ranching, with the consequent reduction of environmental services, such as seed dispersal, due to lack of primary dispersers, scarcity of adequate sites for seedling establishment and competition with grasses. This study evaluated if, in these harsh environments, ants can promote the colonization of arboreal species through directed dispersion of seeds towards the nests. Ten seeds of each ...

  13. Predicting dispersal of auto-gyrating fruit in tropical trees: a case study from the Dipterocarpaceae.

    Science.gov (United States)

    Smith, James R; Bagchi, Robert; Ellens, Judith; Kettle, Chris J; Burslem, David F R P; Maycock, Colin R; Khoo, Eyen; Ghazoul, Jaboury

    2015-05-01

    Seed dispersal governs the distribution of plant propagules in the landscape and hence forms the template on which density-dependent processes act. Dispersal is therefore a vital component of many species coexistence and forest dynamics models and is of applied value in understanding forest regeneration. Research on the processes that facilitate forest regeneration and restoration is given further weight in the context of widespread loss and degradation of tropical forests, and provides impetus to improve estimates of seed dispersal for tropical forest trees. South-East Asian lowland rainforests, which have been subject to severe degradation, are dominated by trees of the Dipterocarpaceae family which constitute over 40% of forest biomass. Dipterocarp dispersal is generally considered to be poor given their large, gyration-dispersed fruits. However, there is wide variability in fruit size and morphology which we hypothesize mechanistically underpins dispersal potential through the lift provided to seeds mediated by the wings. We explored experimentally how the ratio of fruit wing area to mass ("inverse wing loading," IWL) explains variation in seed dispersal kernels among 13 dipterocarp species by releasing fruit from a canopy tower. Horizontal seed dispersal distances increased with IWL, especially at high wind speeds. Seed dispersal of all species was predominantly local, with 90% of seed dispersing <10 m, although maximum dispersal distances varied widely among species. We present a generic seed dispersal model for dipterocarps based on attributes of seed morphology and provide modeled seed dispersal kernels for all dipterocarp species with IWLs of 1-50, representing 75% of species in Borneo.

  14. A brief history of seed size.

    Science.gov (United States)

    Moles, Angela T; Ackerly, David D; Webb, Campbell O; Tweddle, John C; Dickie, John B; Westoby, Mark

    2005-01-28

    Improved phylogenies and the accumulation of broad comparative data sets have opened the way for phylogenetic analyses to trace trait evolution in major groups of organisms. We arrayed seed mass data for 12,987 species on the seed plant phylogeny and show the history of seed size from the emergence of the angiosperms through to the present day. The largest single contributor to the present-day spread of seed mass was the divergence between angiosperms and gymnosperms, whereas the widest divergence was between Celastraceae and Parnassiaceae. Wide divergences in seed size were more often associated with divergences in growth form than with divergences in dispersal syndrome or latitude. Cross-species studies and evolutionary theory are consistent with this evidence that growth form and seed size evolve in a coordinated manner.

  15. Effects of rodent species, seed species, and predator cues on seed fate

    Science.gov (United States)

    Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

    2011-01-01

    Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat (Dipodomys ordii) and the Great Basin pocket mouse (Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote (Canis latrans) vocalization, (3) coyote scent, (4) red fox (Vulpes vulpes) scent, or (5) short-eared owl (Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass (Achnatherum hymenoides) and bluebunch wheatgrass (Pseudoroegneria spicata), and the non-native cereal rye (Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

  16. Effects of rodent species, seed species, and predator cues on seed fate

    Science.gov (United States)

    Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

    2011-07-01

    Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat ( Dipodomys ordii) and the Great Basin pocket mouse ( Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote ( Canis latrans) vocalization, (3) coyote scent, (4) red fox ( Vulpes vulpes) scent, or (5) short-eared owl ( Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass ( Achnatherum hymenoides) and bluebunch wheatgrass ( Pseudoroegneria spicata), and the non-native cereal rye ( Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

  17. Two thrush species as dispersers of Miconia prasina (Sw. DC. (Melastomataceae: an experimental approach

    Directory of Open Access Journals (Sweden)

    MAS. Alves

    Full Text Available We carried out a seed germination experiment using two thrush species in captivity. We compared the number of germinated seeds and germination time of control seeds (manually removed from fruits and ingested seeds of Miconia prasina by two bird species, Turdus albicollis and T. amaurochalinus, and also compared retention times of seeds by both thrush species. Control seeds germinated more frequently than those ingested for one species, T. albicollis. The germination time of ingested seeds by T. amaurochalinus was similar to the control seeds but seeds ingested by T. albicollis took longer to germinate than the controls. Both thrush species had a similar seed defecation pattern. The cumulative number of defecated seeds increased by 2 hours after fruit ingestion. At the end of the first 30 minutes both species had already defecated approximately 50% of the seeds ingested Our results suggest that both species could act as disperser agents of M. prasina.

  18. Between-site differences in the scale of dispersal and gene flow in red oak.

    Directory of Open Access Journals (Sweden)

    Emily V Moran

    Full Text Available BACKGROUND: Nut-bearing trees, including oaks (Quercus spp., are considered to be highly dispersal limited, leading to concerns about their ability to colonize new sites or migrate in response to climate change. However, estimating seed dispersal is challenging in species that are secondarily dispersed by animals, and differences in disperser abundance or behavior could lead to large spatio-temporal variation in dispersal ability. Parentage and dispersal analyses combining genetic and ecological data provide accurate estimates of current dispersal, while spatial genetic structure (SGS can shed light on past patterns of dispersal and establishment. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we estimate seed and pollen dispersal and parentage for two mixed-species red oak populations using a hierarchical bayesian approach. We compare these results to those of a genetic ML parentage model. We also test whether observed patterns of SGS in three size cohorts are consistent with known site history and current dispersal patterns. We find that, while pollen dispersal is extensive at both sites, the scale of seed dispersal differs substantially. Parentage results differ between models due to additional data included in bayesian model and differing genotyping error assumptions, but both indicate between-site dispersal differences. Patterns of SGS in large adults, small adults, and seedlings are consistent with known site history (farmed vs. selectively harvested, and with long-term differences in seed dispersal. This difference is consistent with predator/disperser satiation due to higher acorn production at the low-dispersal site. While this site-to-site variation results in substantial differences in asymptotic spread rates, dispersal for both sites is substantially lower than required to track latitudinal temperature shifts. CONCLUSIONS: Animal-dispersed trees can exhibit considerable spatial variation in seed dispersal, although patterns may

  19. Spanish juniper gain expansion opportunities by counting on a functionally diverse dispersal assemblage community.

    Science.gov (United States)

    Escribano-Ávila, Gema; Pías, Beatriz; Sanz-Pérez, Virginia; Virgós, Emilio; Escudero, Adrián; Valladares, Fernando

    2013-10-01

    Seed dispersal is typically performed by a diverse array of species assemblages with different behavioral and morphological traits which determine dispersal quality (DQ, defined as the probability of recruitment of a dispersed seed). Fate of ecosystems to ongoing environmental changes is critically dependent on dispersal and mainly on DQ in novel scenarios. We assess here the DQ, thus the multiplicative effect of germination and survival probability to the first 3 years of life, for seeds dispersed by several bird species (Turdus spp.) and carnivores (Vulpes vulpes, Martes foina) in mature woodland remnants of Spanish juniper (Juniperus thurifera) and old fields which are being colonized by this species. Results showed that DQ was similar in mature woodlands and old fields. Germination rate for seeds dispersed by carnivores (11.5%) and thrushes (9.12%) was similar, however, interacted with microhabitat suitability. Seeds dispersed by carnivores reach the maximum germination rate on shrubs (16%), whereas seeds dispersed by thrushes did on female juniper canopies (15.5) indicating that each group of dispersers performed a directed dispersal. This directional effect was diluted when survival probability was considered: thrushes selected smaller seeds which had higher mortality in the seedling stage (70%) in relation to seedlings dispersed by carnivores (40%). Overall, thrushes resulted low-quality dispersers which provided a probability or recruitment of 2.5%, while a seed dispersed by carnivores had a probability of recruitment of 6.5%. Our findings show that generalist dispersers (i.e., carnivores) can provide a higher probability of recruitment than specialized dispersers (i.e., Turdus spp.). However, generalist species are usually opportunistic dispersers as their role as seed dispersers is dependent on the availability of trophic resources and species feeding preferences. As a result, J. thurifera dispersal community is composed by two functional groups of

  20. The Analysis of Mutual Fund Performance: Evidence from U.S. Equity Mutual Funds

    NARCIS (Netherlands)

    D.P. Budiono (Diana)

    2010-01-01

    textabstractWe study the mutual fund performance for about 45 years. There are several key points that we can withdraw from this dissertation. First, to study the persistence of mutual fund performance, it is important to consider time-varying exposures because when they are ignored, the persistence

  1. Weed seeds on clothing: a global review.

    Science.gov (United States)

    Ansong, Michael; Pickering, Catherine

    2014-11-01

    Weeds are a major threat to biodiversity including in areas of high conservation value. Unfortunately, people may be unintentionally introducing and dispersing weed seeds on their clothing when they visit these areas. To inform the management of these areas, we conducted a systematic quantitative literature review to determine the diversity and characteristics of species with seeds that can attach and be dispersed from clothing. Across 21 studies identified from systematic literature searches on this topic, seeds from 449 species have been recorded on clothing, more than double the diversity found in a previous review. Nearly all of them, 391 species, are listed weeds in one or more countries, with 58 classified as internationally-recognised environmental weeds. When our database was compared with weed lists from different countries and continents we found that clothing can carry the seeds of important regional weeds. A total of 287 of the species are listed as aliens in one or more countries in Europe, 156 are invasive species/noxious weeds in North America, 211 are naturalized alien plants in Australia, 97 are alien species in India, 33 are invasive species in China and 5 are declared weeds/invaders in South Africa. Seeds on the clothing of hikers can be carried to an average distance of 13 km, and where people travel in cars, trains, planes and boats, the seeds on their clothing can be carried much further. Factors that affect this type of seed dispersal include the type of clothing, the type of material the clothing is made from, the number and location of the seeds on plants, and seed traits such as adhesive and attachment structures. With increasing use of protected areas by tourists, including in remote regions, popular protected areas may be at great risk of biological invasions by weeds with seeds carried on clothing. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Dispersal distance as a benefit of myrmecochory.

    Science.gov (United States)

    Andersen, A N

    1988-05-01

    Nutrient-enrichment and predator avoidance are generally considered the major benefits of myrmecochory, but this is apparently not so in Australia where some of the greatest known concentrations of myrmecochorus plants occur. Here I demonstrate that distance dispersal is a potential benefit of myrmecochory in the Australian environment. Although mean dispersal distance at a site in southeastern Australia was only 2.1 m, the dispersal curve was characterised by a narrow peak and long tail. A dispersal curve of this shape has been shown by Green (1983) to be optimal when safe sites for seedling establishment are rare, as is typically the case for Australian myrmecochores in the absence of fire. Both mean disperal distance and shape of the dispersal curve are influenced strongly by nest density and dispersion, population size, and territoriality of seed-dispersing ants. I argue that distance dispersal is likely to be a benefit of myrmecochory throughout Australia, independent of any targeting of seeds to ant nests.

  3. Ecosystem services from keystone species: diversionary seeding and seed-caching desert rodents can enhance Indian ricegrass seedling establishment

    Science.gov (United States)

    Longland, William; Ostoja, Steven M.

    2013-01-01

    Seeds of Indian ricegrass (Achnatherum hymenoides), a native bunchgrass common to sandy soils on arid western rangelands, are naturally dispersed by seed-caching rodent species, particularly Dipodomys spp. (kangaroo rats). These animals cache large quantities of seeds when mature seeds are available on or beneath plants and recover most of their caches for consumption during the remainder of the year. Unrecovered seeds in caches account for the vast majority of Indian ricegrass seedling recruitment. We applied three different densities of white millet (Panicum miliaceum) seeds as “diversionary foods” to plots at three Great Basin study sites in an attempt to reduce rodents' over-winter cache recovery so that more Indian ricegrass seeds would remain in soil seedbanks and potentially establish new seedlings. One year after diversionary seed application, a moderate level of Indian ricegrass seedling recruitment occurred at two of our study sites in western Nevada, although there was no recruitment at the third site in eastern California. At both Nevada sites, the number of Indian ricegrass seedlings sampled along transects was significantly greater on all plots treated with diversionary seeds than on non-seeded control plots. However, the density of diversionary seeds applied to plots had a marginally non-significant effect on seedling recruitment, and it was not correlated with recruitment patterns among plots. Results suggest that application of a diversionary seed type that is preferred by seed-caching rodents provides a promising passive restoration strategy for target plant species that are dispersed by these rodents.

  4. Viability of small seeds found in feces of the Central American tapir on Barro Colorado Island, Panama

    NARCIS (Netherlands)

    Capece, P.I.; Aliaga-Rossel, E.; Jansen, P.A.

    2013-01-01

    Tapirs are known as effective dispersers of large-seeded tree species, but their role in dispersing small-seeded plant species has yet to be established. Tapir feces have been reported to contain large numbers of small seeds, but whether these are viable has rarely been evaluated. We determined the

  5. Elections to the Mutual Aid Fund

    CERN Multimedia

    2016-01-01

    Every two years, according to Article 6 of the Regulations of the Mutual Aid Fund, the Committee of the Mutual Aid Fund must renew one third of its membership. This year three members are outgoing. Of these three, two will stand again and one will not.   Candidates should be ready to give approximately two hours a month during working time to the Fund whose aim is to assist colleagues in financial difficulties. We invite applications from CERN Staff who wish to stand for election as a member of the CERN Mutual Aid Fund to send in their application before 17 June 2016, by email to the Fund’s President, Connie Potter (connie.potter@cern.ch).

  6. Mutual Fund Flight-to-Liquidity

    DEFF Research Database (Denmark)

    Rzeznik, Aleksandra

    This paper examines the liquidity choices of mutual funds during times of market uncertainty. I find that when markets are uncertain, mutual funds actively increase the liquidity of their portfolio { often referred to as a `flight-to-liquidity.' In aggregate, mutual fund behaviour has implications...... for the market; the market driven flight-toliquidity places upward pressure on the liquidity premium. I examine the underlying mechanisms driving fund behaviour. I show that market volatility is associated with lower fund performance and withdrawals, which causes funds to adjust the composition...... of their portfolio towards more liquid assets in order to meet potential redemptions. This causal chain is consistent with Vayanos (2004), who argues that fund managers are investors with time-varying liquidity preferences due to threat of withdrawal. Aggregated over funds, the effect is substantial: a one standard...

  7. Mutual Fund Flight-to-Liquidity

    DEFF Research Database (Denmark)

    Rzeznik, Aleksandra

    This paper examines the liquidity choices of mutual funds during times of market uncertainty. I find that when markets are uncertain, mutual funds actively increase the liquidity of their portfolio – often referred to as a ‘flight-to-liquidity.’ In aggregate, mutual fund behaviour has implications...... for the market; the market driven flight-toliquidity places upward pressure on the liquidity premium. I examine the underlying mechanisms driving fund behaviour. I show that market volatility is associated with lower fund performance and withdrawals, which causes funds to adjust the composition...... of their portfolio towards more liquid assets in order to meet potential redemptions. This causal chain is consistent with Vayanos (2004), who argues that fund managers are investors with time-varying liquidity preferences due to threat of withdrawal. Aggregated over funds, the effect is substantial: a one standard...

  8. Distribution of mutual information in multipartite states

    Energy Technology Data Exchange (ETDEWEB)

    Maziero, Jonas, E-mail: jonasmaziero@gmail.com [Universidade Federal do Pampa (UNIPAMPA), Bage, RS (Brazil); Universidade Federal de Santa Maria (UFSM), RS (Brazil). Departamento de Fisica

    2014-07-01

    Using the relative entropy of total correlation, we derive an expression relating the mutual information of n-partite pure states to the sum of the mutual informations and entropies of its marginals and analyze some of its implications. Besides, by utilizing the extended strong subadditivity of von Neumann entropy, we obtain generalized monogamy relations for the total correlation in three-partite mixed states. These inequalities lead to a tight lower bound for this correlation in terms of the sum of the bipartite mutual informations. We use this bound to propose a measure for residual three-partite total correlation and discuss the non-applicability of this kind of quantifier to measure genuine multiparty correlations. (author)

  9. MISTIC: mutual information server to infer coevolution

    DEFF Research Database (Denmark)

    Simonetti, Franco L.; Teppa, Elin; Chernomoretz, Ariel

    2013-01-01

    MISTIC (mutual information server to infer coevolution) is a web server for graphical representation of the information contained within a MSA (multiple sequence alignment) and a complete analysis tool for Mutual Information networks in protein families. The server outputs a graphical visualization...... containing all results can be downloaded. The server is available at http://mistic.leloir.org.ar. In summary, MISTIC allows for a comprehensive, compact, visually rich view of the information contained within an MSA in a manner unique to any other publicly available web server. In particular, the use...... of several information-related quantities using a circos representation. This provides an integrated view of the MSA in terms of (i) the mutual information (MI) between residue pairs, (ii) sequence conservation and (iii) the residue cumulative and proximity MI scores. Further, an interactive interface...

  10. Tsallis Mutual Information for Document Classification

    Directory of Open Access Journals (Sweden)

    Màrius Vila

    2011-09-01

    Full Text Available Mutual information is one of the mostly used measures for evaluating image similarity. In this paper, we investigate the application of three different Tsallis-based generalizations of mutual information to analyze the similarity between scanned documents. These three generalizations derive from the Kullback–Leibler distance, the difference between entropy and conditional entropy, and the Jensen–Tsallis divergence, respectively. In addition, the ratio between these measures and the Tsallis joint entropy is analyzed. The performance of all these measures is studied for different entropic indexes in the context of document classification and registration.

  11. Frugivory and potential of birds as dispersers of Siparuna guianensis.

    Science.gov (United States)

    Gonçalves, V F; Silva, A M; Baesse, C Q; Melo, C

    2015-05-01

    Siparuna guianensis is a neotropical tree species, found both on edge and interior of forest fragments, mainly on understory and regeneration areas. The fruit are zoochorous with a sweet aril. This work aims to determine the bird species that eat the fruits of S. guianensis in a semi deciduous forest fragment in Brazilian Cerrado and measure which species have the highest potential as seed dispersers. Seven individuals of S. guianensis were sampled, totaling 69 hours. A hundred and fifty four visits were registered by seven species of birds. Antilophia galeata had the biggest potential as seed dispersal agent. Antilophia galeata, Lanio penicillatus and Dacnis cayana can be important seed dispersers, since they have a high consumption and visitation rate. The consumption of S. guianensis by species of different feeding guilds can be an important strategy for dispersal of plant species in regeneration habitats, raising the chances of an effective dispersal.

  12. Frugivory and potential of birds as dispersers of Siparuna guianensis

    Directory of Open Access Journals (Sweden)

    VF. Gonçalves

    Full Text Available Siparuna guianensis is a neotropical tree species, found both on edge and interior of forest fragments, mainly on understory and regeneration areas. The fruit are zoochorous with a sweet aril. This work aims to determine the bird species that eat the fruits of S. guianensis in a semi deciduous forest fragment in Brazilian Cerrado and measure which species have the highest potential as seed dispersers. Seven individuals of S. guianensis were sampled, totaling 69 hours. A hundred and fifty four visits were registered by seven species of birds. Antilophia galeata had the biggest potential as seed dispersal agent. Antilophia galeata, Lanio penicillatus and Dacnis cayana can be important seed dispersers, since they have a high consumption and visitation rate. The consumption of S. guianensis by species of different feeding guilds can be an important strategy for dispersal of plant species in regeneration habitats, raising the chances of an effective dispersal.

  13. EMS Response to Mass Casualty Incidents: The Critical Importance of Automatic Statewide Mutual Aid and MCI Training

    Science.gov (United States)

    2008-09-01

    rescue dummies and live individuals) that were placed at the Amphitheatre.61 Upon explosion of the bomb and radiological dispersal device from concert...automatic mutual aid organization serving the state of Illinois and singed on jurisdictions within Wisconsin, Indiana, and Missouri and several cities

  14. Removal of Nonmyrmecochorous Seeds by Ants: Role of Ants in Cattle Grasslands

    Directory of Open Access Journals (Sweden)

    Selene Escobar-Ramírez

    2012-01-01

    Full Text Available Livestock production models prevailing in Colombian Andes are simplified treeless pastures for extensive ranching, with the consequent reduction of environmental services, such as seed dispersal, due to lack of primary dispersers, scarcity of adequate sites for seedling establishment and competition with grasses. This study evaluated if, in these harsh environments, ants can promote the colonization of arboreal species through directed dispersion of seeds towards the nests. Ten seeds of each species were offered to ants in six grazing pastures. Ants removed 25% of the seeds (1827 in 48 hours. Preference for arillated and small-to-medium sized seeds, such as Pithecellobium dulce, and Guazuma ulmifolia, was observed. Cyphomyrmex major, Ectatomma ruidum, Solenopsis geminata and Atta cephalotes were the key ant species in seed removal. It was concluded that functional ant groups present in the pastures could contribute to secondary dispersion of seeds with potential for restoration.

  15. Effects of liana load, tree diameter and distances between conspecifics on seed production in tropical timber trees

    DEFF Research Database (Denmark)

    Nabe-Nielsen, Jacob; Kollmann, Johannes Christian; Peña-Claros, Marielos

    2009-01-01

    Seed production in tropical timber trees is limited by abiotic resources, pollination and pre-dispersal seed predation. Resource availability is influenced by the number of competing trees and by lianas that often reach high densities in disturbed parts of tropical forests. The distance between c...... seed trees can considerably improve seed production. In some species seed production may be further improved by ensuring that seed trees are located far apart....

  16. Natural seed fall in white pine (Pinus strobes L.) stands of varying density

    Science.gov (United States)

    Raymond E. Graber

    1970-01-01

    Seed fall was observed in three stands of mature white pines at stand basal-area densities of 80, 120, and 187 square feet per acre. It was found that the intermediate-density stand produced nearly 50 percent more seed than the stands of other densities. During a good seed year this stand produced 59 pounds of dry sound seed per acre. Most of the seeds were dispersed...

  17. Canonical analysis based on mutual information

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Vestergaard, Jacob Schack

    2015-01-01

    combinations with the information theoretical measure mutual information (MI). We term this type of analysis canonical information analysis (CIA). MI allows for the actual joint distribution of the variables involved and not just second order statistics. While CCA is ideal for Gaussian data, CIA facilitates...

  18. Fast mutual exclusion by the Triangle algorithm

    NARCIS (Netherlands)

    Hesselink, Willem; Buhr, Peter; Dice, David

    2018-01-01

    This paper presents a new starvation-free software algorithm for the N-thread mutual-exclusion problem. In the absence of contention, the algorithm requires only eight write operations and four read operations to enter and leave the critical section; to the best of our knowledge, this is optimal.

  19. Information Content of Mutual Fund Portfolio Disclosure

    NARCIS (Netherlands)

    Y. Wang (Yu)

    2011-01-01

    textabstractAcademic financial economists have been keenly interested in the value of active portfolio management since the seminal paper of Jensen (1968). This book examines the information advantages that active mutual fund managers attain in financial markets through an analysis of disclosed fund

  20. Cheating can stabilize cooperation in mutualisms

    Science.gov (United States)

    Foster, Kevin R; Kokko, Hanna

    2006-01-01

    Mutualisms present a challenge for evolutionary theory. How is cooperation maintained in the face of selection for selfishness and cheating? Both theory and data suggest that partner choice, where one species preferentially directs aid to the more cooperative members of the other species, is central to cooperation in many mutualisms. However, the theory has only so far considered the evolutionary effects of partner choice on one of the species in a mutualism in isolation. Here, we investigate the co-evolution of cooperation and choice in a choosy host and its symbiont. Our model reveals that even though choice and cooperation may be initially selected, it will often be unstable. This is because choice reduces variation in the symbiont and, therefore, tends to remove the selective incentive for its own maintenance (a scenario paralleled in the lek paradox in female choice and policing in within-species cooperation). However, we also show that when variability is reintroduced into symbionts each generation, in the form of less cooperative individuals, choice is maintained. This suggests that the presence of cheaters and cheater species in many mutualisms is central to the maintenance of partner choice and, paradoxically, cooperation itself. PMID:16901844

  1. Mutual Group Hypnosis: A Social Interaction Analysis.

    Science.gov (United States)

    Sanders, Shirley

    Mutual Group Hypnosis is discussed in terms of its similarity to group dynamics in general and in terms of its similarity to a social interaction program (Role Modeling) designed to foster the expression of warmth and acceptance among group members. Hypnosis also fosters a regression to prelogical thought processes in the service of the ego. Group…

  2. Mutual Information, Fisher Information, and Efficient Coding.

    Science.gov (United States)

    Wei, Xue-Xin; Stocker, Alan A

    2016-02-01

    Fisher information is generally believed to represent a lower bound on mutual information (Brunel & Nadal, 1998), a result that is frequently used in the assessment of neural coding efficiency. However, we demonstrate that the relation between these two quantities is more nuanced than previously thought. For example, we find that in the small noise regime, Fisher information actually provides an upper bound on mutual information. Generally our results show that it is more appropriate to consider Fisher information as an approximation rather than a bound on mutual information. We analytically derive the correspondence between the two quantities and the conditions under which the approximation is good. Our results have implications for neural coding theories and the link between neural population coding and psychophysically measurable behavior. Specifically, they allow us to formulate the efficient coding problem of maximizing mutual information between a stimulus variable and the response of a neural population in terms of Fisher information. We derive a signature of efficient coding expressed as the correspondence between the population Fisher information and the distribution of the stimulus variable. The signature is more general than previously proposed solutions that rely on specific assumptions about the neural tuning characteristics. We demonstrate that it can explain measured tuning characteristics of cortical neural populations that do not agree with previous models of efficient coding.

  3. Management of mutual health organizations in Ghana.

    NARCIS (Netherlands)

    Baltussen, R.M.P.M.; Bruce, E.; Rhodes, G.; Narh-Bana, S.A.; Agyepong, I.

    2006-01-01

    OBJECTIVE: Mutual Health Organizations (MHO) emerged in Ghana in the mid-1990s. The organizational structure and financial management of private and public MHO hold important lessons for the development of national health insurance in Ghana, but there is little evidence to date on their features.

  4. INTERNATIONAL COMPARISON OF STANDARDS OF MUTUAL INDUCTANCE,

    Science.gov (United States)

    from the metre and second by the use of similar Campbell standards of mutual inductance. A direct comparison of the units of inductance derived in...the two laboratories has been made, using a third Campbell standard whose value was determined electrically. Comparison of the results established by

  5. Mutual Excitation in Eurozone Sovereign CDS

    NARCIS (Netherlands)

    Aït-Sahalia, Y.; Laeven, R.J.A.; Pelizzon, L.

    2013-01-01

    We study self- and cross-excitation of shocks in the sovereign CDS market, on the basis of a large database of Eurozone sovereign CDS spreads. We adopt a multivariate setting with credit default intensities driven by mutually exciting jump processes, to capture the salient features observed in the

  6. Seasonal variation in the fate of seeds under contrasting logging regimes.

    Directory of Open Access Journals (Sweden)

    Marina Fleury

    Full Text Available Seed predators and dispersers may drive the speed and structure of forest regeneration in natural ecosystems. Rodents and ants prey upon and disperse seeds, yet empirical studies on the magnitude of these effects are lacking. Here, we examined the role of ants and rodents on seed predation in 4 plant species in a successional gradient on a tropical rainforest island. We found that (1 seeds are mostly consumed rather than dispersed; (2 rates of seed predation vary by habitat, season, and species; (3 seed size, shape, and hardness do not affect the probability of being depredated. Rodents were responsible for 70% of seed predation and were negligible (0.14% seed dispersers, whereas ants were responsible for only 2% of seed predation and for no dispersal. We detected seasonal and habitat effects on seed loss, with higher seed predation occurring during the wet season and in old-growth forests. In the absence of predators regulating seed-consumer populations, the densities of these resilient animals explode to the detriment of natural regeneration and may reduce diversity and carrying capacity for consumers and eventually lead to ecological meltdown.

  7. Influence of elaiosome on postdispersal dynamics of an ant-dispersed plant

    Science.gov (United States)

    Garrido, José L.; Rey, Pedro J.; Herrera, Carlos M.

    2009-05-01

    Specialized myrmecochorous plants bear an elaiosome attached to the seed. Ants benefit from food provided by this appendage and plants get their seeds eventually dispersed. Aside from the benefits conferred by seed dispersal, we hypothesize that the influence of the elaiosome might extend to later life history stages such as emergence or survival, but few studies have examined rigorously such delayed effects on seed and seedling dynamics. This paper tests this hypothesis for the ant-dispersed herb Helleborus foetidus. Presence or lack of the elaiosome had some interesting delayed influences. Specifically, our results show that elaiosome removal not only enhanced seedling emergence, but also reduced cumulative long-term seed predation. The combination of these two effects, together with the inherent positive effect of the elaiosome on seed dispersal, highlights the ecological and evolutionary importance of myrmecochorous systems.

  8. Investment in seed physical defence is associated with species' light requirement for regeneration and seed persistence: evidence from Macaranga species in Borneo

    Science.gov (United States)

    The life stage from seed dispersal to seedling emergence is often critical in determining the regeneration success of plants. During this period seeds must survive an array of seed predators and pathogens and germinate under conditions favorable for seedling establishment. To maximise recruitment s...

  9. Comparative Performance Islamic Shares Mutual Funds Between Indonesia And Malaysia

    Directory of Open Access Journals (Sweden)

    Novianto Basuki

    2018-03-01

    Full Text Available The objective of this study is to evaluate the performance of Islamic mutual funds in Indonesia and Malaysia. Research conducted on the types of shares mutual funds in the period 2014 until 2016. The technique sample used was purposive sampling method with 13 Islamic mutual funds in Indonesia and 72 Islamic mutual funds in Malaysia. Fund performance measured by Sharpe index, Treynor index, and Index of jenesen’s Alpha. The results of this study showed in 2014 and 2016 Islamic mutual fund performance be superior to Indonesia than Malaysia. While in 2015 Islamic mutual fund performance Malaysia be superior compared to Indonesia. Based on the results of this research, it is recommended for investment managers to increase the publication of and understanding of mutual funds so that more potential investors who are interested in investing in mutual funds in particular Islamic mutual funds.

  10. Dispersal limitation of Tillandsia species correlates with rain and host structure in a central Mexican tropical dry forest.

    Science.gov (United States)

    Victoriano-Romero, Elizabeth; Valencia-Díaz, Susana; Toledo-Hernández, Víctor Hugo; Flores-Palacios, Alejandro

    2017-01-01

    Seed dispersal permits the colonization of favorable habitats and generation of new populations, facilitating escape from habitats that are in decline. There is little experimental evidence of the factors that limit epiphyte dispersion towards their hosts. In a tropical dry forest in central Mexico, we monitored the phenology of dispersion of epiphyte species of the genus Tillandsia; we tested experimentally whether precipitation could cause failures in seed dispersal and whether seed capture differs among vertical strata and between host species with high (Bursera copallifera) and low (Conzattia multiflora) epiphyte loads. With the exception of one species that presents late dispersion and low abundance, all of the species disperse prior to the onset of the rainy season. However, early rains immobilize the seeds, affecting up to 24% of the fruits in species with late dispersion. We observed that Tillandsia seeds reach both Bursera and Conzattia hosts, but found that adherence to the host is 4-5 times higher in Bursera. Furthermore, seeds liberated from Bursera travel shorter distances and up to half may remain within the same crown, while the highest seed capture takes place in the upper strata of the trees. We conclude that dispersion of Tillandsia seeds is limited by early rains and by the capture of seeds within the trees where populations concentrate. This pattern of capture also helps to explain the high concentrations of epiphytes in certain hosts, while trees with few epiphytes can be simultaneously considered deficient receivers and efficient exporters of seeds.

  11. Dispersal limitation of Tillandsia species correlates with rain and host structure in a central Mexican tropical dry forest.

    Directory of Open Access Journals (Sweden)

    Elizabeth Victoriano-Romero

    Full Text Available Seed dispersal permits the colonization of favorable habitats and generation of new populations, facilitating escape from habitats that are in decline. There is little experimental evidence of the factors that limit epiphyte dispersion towards their hosts. In a tropical dry forest in central Mexico, we monitored the phenology of dispersion of epiphyte species of the genus Tillandsia; we tested experimentally whether precipitation could cause failures in seed dispersal and whether seed capture differs among vertical strata and between host species with high (Bursera copallifera and low (Conzattia multiflora epiphyte loads. With the exception of one species that presents late dispersion and low abundance, all of the species disperse prior to the onset of the rainy season. However, early rains immobilize the seeds, affecting up to 24% of the fruits in species with late dispersion. We observed that Tillandsia seeds reach both Bursera and Conzattia hosts, but found that adherence to the host is 4-5 times higher in Bursera. Furthermore, seeds liberated from Bursera travel shorter distances and up to half may remain within the same crown, while the highest seed capture takes place in the upper strata of the trees. We conclude that dispersion of Tillandsia seeds is limited by early rains and by the capture of seeds within the trees where populations concentrate. This pattern of capture also helps to explain the high concentrations of epiphytes in certain hosts, while trees with few epiphytes can be simultaneously considered deficient receivers and efficient exporters of seeds.

  12. Interactive effects between physical forces and ecosystem engineers on seed burial: a case study using Spartina anglica

    NARCIS (Netherlands)

    Zhu, Z.; Cozzoli, F.; Chu, N.; Salvador, M.; Ysebaert, T.; Zhang, L.; Herman, P.M.J.; Bouma, T.J.

    2015-01-01

    Seed burial (i.e. vertical seed dispersal) has become increasingly valued for its relevance for seed fate and plant recruitment. While ecosystem engineers have been generally considered as the most important drivers of seed burial, the role of physical forces, such as wind or water flow, has been

  13. Interactive effects between physical forces and ecoystem engieneers on seed burial: a case study using Spartina anglica

    NARCIS (Netherlands)

    Zhu, Z.; Cozzoli, F.; Chu, N.; Salvador, M.; Ysebaert, T.; Zhang, L.; Herman, P.M.J.; Bouma, T.J.

    2016-01-01

    Seed burial (i.e. vertical seed dispersal) has become increasingly valued for its relevance for seed fate and plant recruitment. While ecosystem engineers have been generally considered as the most important drivers of seed burial, the role of physical forces, such as wind or water flow, has been

  14. A role for parasites in stabilising the fig-pollinator mutualism.

    Directory of Open Access Journals (Sweden)

    Derek W Dunn

    2008-03-01

    Full Text Available Mutualisms are interspecific interactions in which both players benefit. Explaining their maintenance is problematic, because cheaters should outcompete cooperative conspecifics, leading to mutualism instability. Monoecious figs (Ficus are pollinated by host-specific wasps (Agaonidae, whose larvae gall ovules in their "fruits" (syconia. Female pollinating wasps oviposit directly into Ficus ovules from inside the receptive syconium. Across Ficus species, there is a widely documented segregation of pollinator galls in inner ovules and seeds in outer ovules. This pattern suggests that wasps avoid, or are prevented from ovipositing into, outer ovules, and this results in mutualism stability. However, the mechanisms preventing wasps from exploiting outer ovules remain unknown. We report that in Ficus rubiginosa, offspring in outer ovules are vulnerable to attack by parasitic wasps that oviposit from outside the syconium. Parasitism risk decreases towards the centre of the syconium, where inner ovules provide enemy-free space for pollinator offspring. We suggest that the resulting gradient in offspring viability is likely to contribute to selection on pollinators to avoid outer ovules, and by forcing wasps to focus on a subset of ovules, reduces their galling rates. This previously unidentified mechanism may therefore contribute to mutualism persistence independent of additional factors that invoke plant defences against pollinator oviposition, or physiological constraints on pollinators that prevent oviposition in all available ovules.

  15. Microscale Insight into Microbial Seed Banks.

    Science.gov (United States)

    Locey, Kenneth J; Fisk, Melany C; Lennon, J T

    2016-01-01

    Microbial dormancy leads to the emergence of seed banks in environmental, engineered, and host-associated ecosystems. These seed banks act as reservoirs of diversity that allow microbes to persist under adverse conditions, including extreme limitation of resources. While microbial seed banks may be influenced by macroscale factors, such as the supply of resources, the importance of microscale encounters between organisms and resource particles is often overlooked. We hypothesized that dimensions of spatial, trophic, and resource complexity determine rates of encounter, which in turn, drive the abundance, productivity, and size of seed banks. We tested this using >10,000 stochastic individual based models (IBMs) that simulated energetic, physiological, and ecological processes across combinations of resource, spatial, and trophic complexity. These IBMs allowed realistic dynamics and the emergence of seed banks from ecological selection on random variation in species traits. Macroscale factors like the supply and concentration of resources had little effect on resource encounter rates. In contrast, encounter rates were strongly influenced by interactions between dispersal mode and spatial structure, and also by the recalcitrance of resources. In turn, encounter rates drove abundance, productivity, and seed bank dynamics. Time series revealed that energetically costly traits can lead to large seed banks and that recalcitrant resources can lead to greater stability through the formation of seed banks and the slow consumption of resources. Our findings suggest that microbial seed banks emerge from microscale dimensions of ecological complexity and their influence on resource limitation and energetic costs.

  16. Seed lipids.

    Science.gov (United States)

    Wolff, I A

    1966-12-02

    Many of the newly discovered seedoil acids have reactive or unusual functional groups or other facets of molecular structure that permit their ready differentiation from oleic, linoleic, linolenic, and the other most prevalent saturated and unsaturated long-chain fatty acids. The recognition and availability of the new acids, coupled with methods that make detection and determination easy, will help studies of lipid biosynthesis in the plant and of lipid metabolism and utilization in animals, and will stimulate more studies in depth on the fine points of seedlipid structure. Correlations of structural patterns in seed lipids of particular groups of plants with classical taxonomic categories will permit clarifications, raise needed questions concerning classifications, and accelerate research in chemotaxonomy and phylogenetics. Seed lipids are particularly well suited for establishing relationships among plants because of their great variety in structure compared to the more limited structural types of amino acids, sugars, purines, and many other plant substances. The newly characterized seed oils are potentially important industrial raw materials whenever they come from agronomically promising plant species. The molecular structures of seed triglycerides have major influence on their physical properties and therefore advances in knowledge in that sphere have practical implications. For example, the unusual characteristics of cocoa butter that make it so valuable for food and confectionery use are attributed to the specific arrangement of fatty acids it its triglycerides. The glycerides are almost all 2-oleic-1,3-disaturated acid triglycerides. The physical characteristics of lard are advantageously changed by catalytically rearranging fatty acyl groups among the glycerides initially in the fat to achieve a more nearly random distribution, followed sometimes by further fractionation to remove more saturated glycerides. Through this change of glyceride structures a

  17. Organic leek seed production - securing seed quality

    DEFF Research Database (Denmark)

    Deleuran, Lise Christina; Boelt, Birte

    2011-01-01

    seeds. Tunnel production is a means of securing seed of high genetic purity and quality, and organic leek (Allium porrum L.) seed production was tested in tunnels in Denmark. The present trial focused on steckling size and in all years large stecklings had a positive effect on both seed yield...

  18. seed oil

    African Journals Online (AJOL)

    Wara

    found to be 2.0 cm which is lower than that of Jatropha oil soap(5.4cm), Sesame oil soap(4.8cm), Cotton seed oil soap(4.5cm) and shea nut soap(4.2cm),t higher than that of Castor oil soap(1.6cm) and Castor glycerine soap(1.4cm). The soap was milk in colour and slightly soluble in distilled water. Keywords: Neem oil ...

  19. Genomewide association analysis for awn length linked to the seed ...

    Indian Academy of Sciences (India)

    In wild plants, long awns have been reported to aid in seed dispersal, burial and protecting grains from animal predation (Elbaum et al. 2007). However, a long awn-like seed shattering is not a desirable trait, particularly during crop harvest because it decreases grain yield, which has not been selected during domestication.

  20. Evaluation of essential minerals in pumpkin seeds by EDXRF

    International Nuclear Information System (INIS)

    Boaro, Flavia Araujo; Zacari, Cristiane Z.; Scapin, Marcos A.; Aquino, Reginaldo R.

    2013-01-01

    Pumpkin seeds, marketed in the Municipal Market of Sao Paulo, Brazil, were analyzed using the Energy Dispersive of X-ray Fluorescence technique (EDXRF) seeking to evaluate the content of the main essential minerals present in these seeds, and their contribution to human nutrition

  1. Camera-trapping and seed-labelling reveals widespread granivory ...

    African Journals Online (AJOL)

    Many plant–animal interactions can be challenging to directly observe, due to species being small, cryptic and/or nocturnal. Previous research on seed predation and dispersal by rodents in the Fynbos Biome of South Africa has relied on indirect evidence, as methods for directly monitoring rodent–seed interactions were ...

  2. Bird Perches Increase Forest Seeds on Puerto Rican Landslides.

    Science.gov (United States)

    Aaron B. Shiels; Lawrence R. Walker

    2003-01-01

    Landslides result in the loss of vertical vegetative structure, soil nutrients, and the soil seed bank. These losses impede timely recovery of tropical forest communities. In this study we added bird perches to six Puerto Rican landslides with three types of surfaces (bare, climbing fern, grass) in an effort to facilitate inputs of forest seeds through bird dispersal...

  3. Scatter-and clump-dispersal and seedling demography: hypothesis and implications.

    Science.gov (United States)

    Howe, H F

    1989-05-01

    Fruit-eating animals deposit viable seeds in patterns that determine the conditions under which seeds and seedlings live or die. Many tree species are scatter-dispersed by birds, bats, or other small frugivores that regurgitate, defecate, or drop seeds singly or in pairs. These scatterdispersed plant species normally recruit as isolated individuals, and are unlikely to evolve exceptional resistance to herbivores, pathogens, or to other sources of density-dependent seed or seedling mortality. Other tree species are clump-dispersed by larger terrestrial or arboreal frugivores that defecate seeds in masses which produce bouquets of seedlings. Because their seeds invariably germinate in close proximity to other seedlings, clump-dispersed species necessarily evolve chemical or mechanical defenses against seed predators, pathogens, and herbivores that act in a densitydependent manner.Population and genetic attributes should reflect this basic dichotomy in the conditions of seedling recruitment. I predict that seedlings of scatter-dispersed species rarely survive near parents or in dense aggregations under frugivore roosts. Seed dispersal should be mandatory, often to light gaps or other special habitats. Outbred adults and juveniles are expected to exist at low densities in loose aggregations or random distributions. Seedlings of clump-dispersed trees are pre-adapted for survival in dense aggregations near parents, as well as in fecal clumps. Substantial recruitment of juveniles and young adults should occur from undispersed seeds under and near parent trees. Such species should be common, highly aggregated, and show strong genetic family structure. Because recruitment requires dispersal, scatter-dispersed plant species should be especially vulnerable to loss of dispersal agents. Because offspring consistently recruit near parents, clump-dispersed plants should be less vulnerable to temporary loss of dispersal agents.

  4. Mutual Learning in the European Employment Strategy

    DEFF Research Database (Denmark)

    Nedergaard, Peter

    Mutual learning among the Member States is the primary purpose of the employment policy of the European Union. The two most important questions in this regard are how learning occurs and how much learning takes place. In this article I argue that the existing analyses of the effects of learning...... in the European employment strategy have been either determined by the sender's interests or have underestimated how mutual learning between countries takes place. In stead the article develops a constructivist approach to learning and uses it to generate some concrete hypothesis about when learning in committees...... is most likely to take place. Afterwards, this constructivist approach is used to analyse the institutional framework surrounding the European employment strategy in order to evaluate whether the potential for learning is optimal. Finally, the article concludes that even though some basic premises...

  5. Mutual information in the Tangled Nature Model

    DEFF Research Database (Denmark)

    Jones, Dominic; Sibani, Paolo

    2010-01-01

    We consider the concept of mutual information in ecological networks, and use this idea to analyse the Tangled Nature model of co-evolution. We show that this measure of correlation has two distinct behaviours depending on how we define the network in question: if we consider only the network of ...... of viable species this measure increases, whereas for the whole system it decreases. It is suggested that these are complimentary behaviours that show how ecosystems can become both more stable and better adapted.......We consider the concept of mutual information in ecological networks, and use this idea to analyse the Tangled Nature model of co-evolution. We show that this measure of correlation has two distinct behaviours depending on how we define the network in question: if we consider only the network...

  6. Predicting RNA Structure Using Mutual Information

    DEFF Research Database (Denmark)

    Freyhult, E.; Moulton, V.; Gardner, P. P.

    2005-01-01

    package. Conclusion: MIfold provides a useful supplementary tool to programs such as RNA Structure Logo, RNAalifold and COVE, and should be useful for automatically generating structural predictions for databases such as Rfam. Availability: MIfold is freely available from http......Background: With the ever-increasing number of sequenced RNAs and the establishment of new RNA databases, such as the Comparative RNA Web Site and Rfam, there is a growing need for accurately and automatically predicting RNA structures from multiple alignments. Since RNA secondary structure...... is often conserved in evolution, the well known, but underused, mutual information measure for identifying covarying sites in an alignment can be useful for identifying structural elements. This article presents MIfold, a MATLAB(R) toolbox that employs mutual information, or a related covariation measure...

  7. Fast mutual-information-based contrast enhancement

    Science.gov (United States)

    Cao, Gang; Yu, Lifang; Tian, Huawei; Huang, Xianglin; Wang, Yongbin

    2017-07-01

    Recently, T. Celik proposed an effective image contrast enhancement (CE) method based on spatial mutual information and PageRank (SMIRANK). According to the state-of-the-art evaluation criteria, it achieves the best visual enhancement quality among existing global CE methods. However, SMIRANK runs much slower than the other counterparts, such as histogram equalization (HE) and adaptive gamma correction. Low computational complexity is also required for good CE algorithms. In this paper, we novelly propose a fast SMIRANK algorithm, called FastSMIRANK. It integrates both spatial and gray-level downsampling into the generation of pixel value mapping function. Moreover, the computation of rank vectors is speeded up by replacing PageRank with a simple yet efficient row-based operation of mutual information matrix. Extensive experimental results show that the proposed FastSMIRANK could accelerate the processing speed of SMIRANK by about 20 times, and is even faster than HE. Comparable enhancement quality is preserved simultaneously.

  8. Tourism versus spatial order: mutual relations

    OpenAIRE

    Meyer, Beata

    2012-01-01

    The relation between tourism and the spatial environment is characterized by mutual interaction. The proliferation of tourism and massive tourism development intensifies its impact on the spatial environment, yet the focus is usually placed on environmental degradation and the resulting distortion of spatial order. Concurrently, the significance of the spatial environment, and spatial order in particular, as one of the determinants of tourism development is understated. On a theoretical plane...

  9. Diversification and coevolution in brood pollination mutualisms: Windows into the role of biotic interactions in generating biological diversity.

    Science.gov (United States)

    Hembry, David H; Althoff, David M

    2016-10-01

    Brood pollination mutualisms-interactions in which specialized insects are both the pollinators (as adults) and seed predators (as larvae) of their host plants-have been influential study systems for coevolutionary biology. These mutualisms include those between figs and fig wasps, yuccas and yucca moths, leafflowers and leafflower moths, globeflowers and globeflower flies, Silene plants and Hadena and Perizoma moths, saxifrages and Greya moths, and senita cacti and senita moths. The high reciprocal diversity and species-specificity of some of these mutualisms have been cited as evidence that coevolution between plants and pollinators drives their mutual diversification. However, the mechanisms by which these mutualisms diversify have received less attention. In this paper, we review key hypotheses about how these mutualisms diversify and what role coevolution between plants and pollinators may play in this process. We find that most species-rich brood pollination mutualisms show significant phylogenetic congruence at high taxonomic scales, but there is limited evidence for the processes of both cospeciation and duplication, and there are no unambiguous examples known of strict-sense contemporaneous cospeciation. Allopatric speciation appears important across multiple systems, particularly in the insects. Host-shifts appear to be common, and widespread host-shifts by pollinators may displace other pollinator lineages. There is relatively little evidence for a "coevolution through cospeciation" model or that coevolution promotes speciation in these systems. Although we have made great progress in understanding the mechanisms by which brood pollination mutualisms diversify, many opportunities remain to use these intriguing symbioses to understand the role of biotic interactions in generating biological diversity. © 2016 Botanical Society of America.

  10. MISTIC: Mutual information server to infer coevolution.

    Science.gov (United States)

    Simonetti, Franco L; Teppa, Elin; Chernomoretz, Ariel; Nielsen, Morten; Marino Buslje, Cristina

    2013-07-01

    MISTIC (mutual information server to infer coevolution) is a web server for graphical representation of the information contained within a MSA (multiple sequence alignment) and a complete analysis tool for Mutual Information networks in protein families. The server outputs a graphical visualization of several information-related quantities using a circos representation. This provides an integrated view of the MSA in terms of (i) the mutual information (MI) between residue pairs, (ii) sequence conservation and (iii) the residue cumulative and proximity MI scores. Further, an interactive interface to explore and characterize the MI network is provided. Several tools are offered for selecting subsets of nodes from the network for visualization. Node coloring can be set to match different attributes, such as conservation, cumulative MI, proximity MI and secondary structure. Finally, a zip file containing all results can be downloaded. The server is available at http://mistic.leloir.org.ar. In summary, MISTIC allows for a comprehensive, compact, visually rich view of the information contained within an MSA in a manner unique to any other publicly available web server. In particular, the use of circos representation of MI networks and the visualization of the cumulative MI and proximity MI concepts is novel.

  11. Hydrodynamic dispersion

    International Nuclear Information System (INIS)

    Pryce, M.H.L.

    1985-01-01

    A dominant mechanism contributing to hydrodynamic dispersion in fluid flow through rocks is variation of travel speeds within the channels carrying the fluid, whether these be interstices between grains, in granular rocks, or cracks in fractured crystalline rocks. The complex interconnections of the channels ensure a mixing of those parts of the fluid which travel more slowly and those which travel faster. On a macroscopic scale this can be treated statistically in terms of the distribution of times taken by a particle of fluid to move from one surface of constant hydraulic potential to another, lower, potential. The distributions in the individual channels are such that very long travel times make a very important contribution. Indeed, while the mean travel time is related to distance by a well-defined transport speed, the mean square is effectively infinite. This results in an asymmetrical plume which differs markedly from a gaussian shape. The distribution of microscopic travel times is related to the distribution of apertures in the interstices, or in the microcracks, which in turn are affected in a complex way by the stresses acting on the rock matrix

  12. Seed Treatment. Manual 92.

    Science.gov (United States)

    Missouri Univ., Columbia. Agricultural Experiment Station.

    This training manual provides information needed to meet minimum EPA standards for certification as a commercial applicator of pesticides in the seed treatment category. The text discusses pests commonly associated with seeds; seed treatment pesticides; labels; chemicals and seed treatment equipment; requirements of federal and state seed laws;…

  13. Seed Treatment. Bulletin 760.

    Science.gov (United States)

    Lowery, Harvey C.

    This manual gives a definition of seed treatment, the types of seeds normally treated, diseases and insects commonly associated with seeds, fungicides and insecticides used, types of equipment used for seed treatment, and information on labeling and coloring of treated seed, pesticide carriers, binders, stickers, and safety precautions. (BB)

  14. Windows of opportunity for germination of riparian species after restoring water level fluctuations: a field experiment with controlled seed banks

    NARCIS (Netherlands)

    Sarneel, J.M.; Janssen, R.H.; Rip, W.J.; Bender, I.; Bakker, E.S.

    2014-01-01

    Restoration activities aiming at increasing vegetation diversity often try to stimulate both dispersal and germination. In wetlands, dispersal and germination are coupled as water and water level fluctuations (WLF) simultaneously influence seed transport and germination conditions (soil moisture).

  15. Species, diaspore volume and body mass matter in gastropod seed feeding behavior.

    Directory of Open Access Journals (Sweden)

    Manfred Türke

    Full Text Available BACKGROUND: Seed dispersal of ant-dispersed plants (myrmecochores is a well studied ecosystem function. Recently, slugs have been found to act as seed dispersers of myrmecochores. The aim of our study was to (1 further generalize the finding that gastropods feed on seeds of myrmecochores and hence may act as seed dispersers, (2 to test whether gastropod body mass and the volume of diaspores have an influence on the seed dispersal potential. METHODOLOGY AND PRINCIPAL FINDINGS: We assessed the seed dispersal potential of four slug and snail species with a set of seven myrmecochorous plant species from seven different plant families common to Central European beech forests. Diaspores differed in shape and size. Gastropods differed in their readiness to feed on diaspores and in the proportion of seeds that were swallowed as a whole, and this readiness generally decreased with increasing diaspore size. Smaller Arionid slugs (58 mm body length; mean mostly fed on the elaiosome but also swallowed small diaspores and therefore not only act as elaiosome consumers, a nutrient rich appendage on myrmecochorous diaspores, but may also disperse seeds. Large Arionid slugs (>100 mm body length swallowed diaspores of all sizes. Diaspores swallowed by gastropods were defecated without damage. Within-species variability in body size also affect seed dispersal potential, as larger individuals of the red slug (Arion rufus swallowed more diaspores of wood anemone (Anemone nemorosa than smaller ones. CONCLUSIONS AND SIGNIFICANCE: Our results help to generalize the finding that gastropods consume and potentially disperse seeds of myrmecochores. The dispersal potential of gastropods is strongly influenced by diaspore size in relation to gastropod size.

  16. Species, diaspore volume and body mass matter in gastropod seed feeding behavior.

    Science.gov (United States)

    Türke, Manfred; Weisser, Wolfgang W

    2013-01-01

    Seed dispersal of ant-dispersed plants (myrmecochores) is a well studied ecosystem function. Recently, slugs have been found to act as seed dispersers of myrmecochores. The aim of our study was to (1) further generalize the finding that gastropods feed on seeds of myrmecochores and hence may act as seed dispersers, (2) to test whether gastropod body mass and the volume of diaspores have an influence on the seed dispersal potential. We assessed the seed dispersal potential of four slug and snail species with a set of seven myrmecochorous plant species from seven different plant families common to Central European beech forests. Diaspores differed in shape and size. Gastropods differed in their readiness to feed on diaspores and in the proportion of seeds that were swallowed as a whole, and this readiness generally decreased with increasing diaspore size. Smaller Arionid slugs (58 mm body length; mean) mostly fed on the elaiosome but also swallowed small diaspores and therefore not only act as elaiosome consumers, a nutrient rich appendage on myrmecochorous diaspores, but may also disperse seeds. Large Arionid slugs (>100 mm body length) swallowed diaspores of all sizes. Diaspores swallowed by gastropods were defecated without damage. Within-species variability in body size also affect seed dispersal potential, as larger individuals of the red slug (Arion rufus) swallowed more diaspores of wood anemone (Anemone nemorosa) than smaller ones. Our results help to generalize the finding that gastropods consume and potentially disperse seeds of myrmecochores. The dispersal potential of gastropods is strongly influenced by diaspore size in relation to gastropod size.

  17. Proteomics and posttranslational proteomics of seed dormancy and germination.

    Science.gov (United States)

    Rajjou, Loïc; Belghazi, Maya; Catusse, Julie; Ogé, Laurent; Arc, Erwann; Godin, Béatrice; Chibani, Kamel; Ali-Rachidi, Sonia; Collet, Boris; Grappin, Philippe; Jullien, Marc; Gallardo, Karine; Job, Claudette; Job, Dominique

    2011-01-01

    The seed is the dispersal unit of plants and must survive the vagaries of the environment. It is the object of intense genetic and genomic studies because processes related to seed quality affect crop yield and the seed itself provides food for humans and animals. Presently, the general aim of postgenomics analyses is to understand the complex biochemical and molecular processes underlying seed quality, longevity, dormancy, and vigor. Due to advances in functional genomics, the recent past years have seen a tremendous progress in our understanding of several aspects of seed development and germination. Here, we describe the proteomics protocols (from protein extraction to mass spectrometry) that can be used to investigate several aspects of seed physiology, including germination and its hormonal regulation, dormancy release, and seed longevity. These techniques can be applied to the study of both model plants (such as Arabidopsis) and crops.

  18. Long-Distance Dispersal of Fungi.

    Science.gov (United States)

    Golan, Jacob J; Pringle, Anne

    2017-07-01

    Dispersal is a fundamental biological process, operating at multiple temporal and spatial scales. Despite an increasing understanding of fungal biodiversity, most research on fungal dispersal focuses on only a small fraction of species. Thus, any discussion of the dispersal dynamics of fungi as a whole is problematic. While abundant morphological and biogeographic data are available for hundreds of species, researchers have yet to integrate this information into a unifying paradigm of fungal dispersal, especially in the context of long-distance dispersal (LDD). Fungal LDD is mediated by multiple vectors, including meteorological phenomena (e.g., wind and precipitation), plants (e.g., seeds and senesced leaves), animals (e.g., fur, feathers, and gut microbiomes), and in many cases humans. In addition, fungal LDD is shaped by both physical constraints on travel and the ability of spores to survive harsh environments. Finally, fungal LDD is commonly measured in different ways, including by direct capture of spores, genetic comparisons of disconnected populations, and statistical modeling and simulations of dispersal data. To unify perspectives on fungal LDD, we propose a synthetic three-part definition that includes (i) an identification of the source population and a measure of the concentration of source inoculum and (ii) a measured and/or modeled dispersal kernel. With this information, LDD is defined as (iii) the distance found within the dispersal kernel beyond which only 1% of spores travel.

  19. MUTUAL CONCESSIONS - SPECIFIC ELEMENT OF THE COMPROMISE/TRANSACTION CONTRACT

    Directory of Open Access Journals (Sweden)

    Georgeta-Bianca Spîrchez

    2012-11-01

    Full Text Available Given the usefulness and practical importance of the compromise contract conclusion and of the amicably dispute resolution, within the business world, we aim to analyze, in what follows, the concrete means by which these kind of settlement are achieved. Two questions become legitimate in the context of concerns about mutual concessions which the parties make in a compromise contract. These questions are the following: “What are the mutual concessions? Do mutual concessions mean equivalent concessions?” and “How mutual concessions are required to complete a valid settlement? Is the requirement of mutual concessions grounded?”

  20. The role of seed mass on the caching decision by agoutis, Dasyprocta leporina (Rodentia: Agoutidae

    Directory of Open Access Journals (Sweden)

    Mauro Galetti

    2010-06-01

    Full Text Available It has been shown that the local extinction of large-bodied frugivores may cause cascading consequences for plant recruitment and overall plant diversity. However, to what extent the resilient mammals can compensate the role of seed dispersal in defaunated sites is poorly understood. Caviomorph rodents, especially Dasyprocta spp., are usually resilient frugivores in hunted forests and their seed caching behavior may be important for many plant species which lack primary dispersers. We compared the effect of the variation in seed mass of six vertebrate-dispersed plant species on the caching decision by the red-rumped agoutis Dasyprocta leporina Linnaeus, 1758 in a land-bridge island of the Atlantic forest, Brazil. We found a strong positive effect of seed mass on seed fate and dispersal distance, but there was a great variation between species. Agoutis never cached seeds smaller than 0.9 g and larger seeds were dispersed for longer distances. Therefore, agoutis can be important seed dispersers of large-seeded species in defaunated forests.

  1. THE COOPERATIVE CREDIT MUTUAL IN BRAZIL.

    Directory of Open Access Journals (Sweden)

    Laércio Baptista da Silva

    2013-06-01

    Full Text Available This study presents an analysis of the reality of credit unions in Brazil, in view of the singular importance of credit unions for the whole society as an alternative to private resources in favor of members of the community where they are located. It confirms that, in Brazil, the mutual credit unions, besides being presented as one of the viable options within the financial system, are also seen as an alternative by which some sectors of society promote the humanization of the financial system by offering credit and return on capital with fairer interest rates.

  2. Mutual Learning in the European Employment Strategy

    DEFF Research Database (Denmark)

    Nedergaard, Peter

    in the European employment strategy have been either determined by the sender's interests or have underestimated how mutual learning between countries takes place. In stead the article develops a constructivist approach to learning and uses it to generate some concrete hypothesis about when learning in committees...... is most likely to take place. Afterwards, this constructivist approach is used to analyse the institutional framework surrounding the European employment strategy in order to evaluate whether the potential for learning is optimal. Finally, the article concludes that even though some basic premises...

  3. Feature Selection Based on Mutual Correlation

    Czech Academy of Sciences Publication Activity Database

    Haindl, Michal; Somol, Petr; Ververidis, D.; Kotropoulos, C.

    2006-01-01

    Roč. 19, č. 4225 (2006), s. 569-577 ISSN 0302-9743. [Iberoamerican Congress on Pattern Recognition. CIARP 2006 /11./. Cancun, 14.11.2006-17.11.2006] R&D Projects: GA AV ČR 1ET400750407; GA MŠk 1M0572; GA AV ČR IAA2075302 EU Projects: European Commission(XE) 507752 - MUSCLE Institutional research plan: CEZ:AV0Z10750506 Keywords : feature selection Subject RIV: BD - Theory of Information Impact factor: 0.402, year: 2005 http://library.utia.cas.cz/separaty/historie/haindl-feature selection based on mutual correlation.pdf

  4. Group-ID based RFID Mutual Authentication

    Directory of Open Access Journals (Sweden)

    LEE, Y.

    2013-11-01

    Full Text Available For passive type RFID tags, EPCglobal Class 1 Generation-2 Revision is used widely as a de facto standard. As it was designed for low cost, it is quite vulnerable to security issues, such as privacy concerns. This paper presents a new RFID mutual authentication protocol, which is designed to be configured on EPC Gen2 platform and to meet various security requirements while providing efficiency using PRNG (Pseudo Random Number Generator. Group-ID is used to minimize the authentication time. Security analysis of the proposed protocol is discussed.

  5. Diaspore trait preferences of dispersing ants.

    Science.gov (United States)

    Reifenrath, Kerstin; Becker, Christine; Poethke, Hans Joachim

    2012-09-01

    Elaiosomes of myrmecochorous plant seeds are known to enhance the attraction of diaspore-dispersing ants by serving as a nutritional reward. However, it remained unclear which (nutritional) compounds affect diaspore preferences of ants. We hypothesized that apart from elaiosome/seed-size ratio, volume, and physical surface of diaspores, the quantity and the composition of fatty acids, amino acids, and sugars strongly influence the diaspore preferences of different species. Chemical (nutritional) profiles as well as structural properties of seeds with and without elaiosomes were analyzed and correlated with observed seed choice behavior of ants. Cafeteria experiments in the field confirmed the enhanced attractiveness of elaiosome-bearing seeds for all three ant species tested (Lasius fuliginosus, Myrmica ruginodis, and Temnothorax nylanderi), although seeds lacking elaiosomes also were transported. In multiple-choice cafeteria experiments with simultaneously offered diaspores of 16 plant species with and without elaiosome and with highly varying structural and chemical properties, all three ant species showed distinct preferences for certain diaspore species. Correlation analyses confirmed that the presence of an elaiosome represents the crucial factor that favors ant diaspore dispersal. In addition, the composition and the content of free amino acids, and to varying degrees fatty acids, were found to significantly affect preferences of each ant species, whereas the effect of single fatty acids acting as chemical triggers for diaspore transport by ants, as supposed by several studies, was not confirmed. In conclusion, although at least some diaspore species lacking elaiosomes attract ants for diaspore removal services by presenting nutritional seed coats, the production of elaiosomes seems to provide a worthwhile investment. Elaiosomes ensure rapid diaspore detection and removal due to chemical cue compounds and by offering a highly nutritional food supply, probably

  6. Grazing influences Stipa breviflora seed germination in desert grasslands of the Inner Mongolia Plateau

    Science.gov (United States)

    Liu, Wenting; Wang, Tianle; Zhang, Shuang; Ding, Lijun

    2018-01-01

    Seed germination plays an important role in determining the composition and regeneration of plant populations (Stipa breviflora). However, the influencing factors and strategies employed for seed germination in desert grasslands under grazing remain unknown. Therefore, in this study, the reproductive allocation, seed density, seed properties, and corresponding seed germination rates of S. breviflora were examined. Possible situations encountered during dispersal were also simulated to determine their effects on seed germination. The results showed that reproductive individual density not subjected to grazing were significantly higher than those subjected to moderate and heavy grazing. For seed density and seed bank in soil, the highest values were observed for the no grazing treatment, followed by the moderate and heavy grazing treatments. The seed density for germination of soil seed banks was nearly one-fourth of seed density during the growing season. In addition, grazing treatments affected the phenotypic characteristics of seeds and reduced the lower limit of the weight of germinable seeds. Awn removal significantly increased germination. The longest germination time was observed for seeds that entered the soil at an angle of 0°. Our research demonstrated that grazing negatively affected the desert grassland edificator. Individual plants adopted different adaptation strategies under different grazing intensities; for example, a fixed proportion of the seed number and seed germination number of S. breviflora in the soil seed bank was maintained by exceeding the minimum weight of a seed for seed germination. During seed dispersion, the awn effectively prevented germination under unfavourable conditions and helped seeds enter the soil at an optimal angle for promoting germination. PMID:29507838

  7. Factoring the dispersion relation in the presence of Lorentz violation

    Energy Technology Data Exchange (ETDEWEB)

    Colladay, Don; McDonald, Patrick; Mullins, David, E-mail: colladay@ncf.ed [New College of Florida, Sarasota, FL 34243 (United States)

    2010-07-09

    We produce an explicit formula for the dispersion relation for the Dirac equation in the standard model extension in the presence of Lorentz violation. Our expression is obtained using novel techniques which exploit the algebra of quaternions. The dispersion relation is found to conveniently factor in two special cases that each involve a mutually exclusive set of nonvanishing Lorentz-violating parameters. This suggests that a useful approach to studies of Lorentz-violating models is to split the parameter space into two separate pieces, each of which yields a simple, tractable dispersion relation that can be used for analysis.

  8. The assembly of ant-farmed gardens: mutualism specialization following host broadening.

    Science.gov (United States)

    Chomicki, Guillaume; Janda, Milan; Renner, Susanne S

    2017-03-15

    Ant-gardens (AGs) are ant/plant mutualisms in which ants farm epiphytes in return for nest space and food rewards. They occur in the Neotropics and Australasia, but not in Africa, and their evolutionary assembly remains unclear. We here use phylogenetic frameworks for important AG lineages in Australasia, namely the ant genus Philidris and domatium-bearing ferns ( Lecanopteris ) and flowering plants in the Apocynaceae ( Hoya and Dischidia ) and Rubiaceae ( Myrmecodia , Hydnophytum , Anthorrhiza , Myrmephytum and Squamellaria ). Our analyses revealed that in these clades, diaspore dispersal by ants evolved at least 13 times, five times in the Late Miocene and Pliocene in Australasia and seven times during the Pliocene in Southeast Asia, after Philidris ants had arrived there, with subsequent dispersal between these two areas. A uniquely specialized AG system evolved in Fiji at the onset of the Quaternary. The farming in the same AG of epiphytes that do not offer nest spaces suggests that a broadening of the ants' plant host spectrum drove the evolution of additional domatium-bearing AG-epiphytes by selecting on pre-adapted morphological traits. Consistent with this, we found a statistical correlation between the evolution of diaspore dispersal by ants and domatia in all three lineages. Our study highlights how host broadening by a symbiont has led to new farming mutualisms. © 2017 The Author(s).

  9. Dormancy-Related Seed Positional Effect in Two Populations of an Annual Grass from Locations of Contrasting Aridity

    OpenAIRE

    Volis, Sergei

    2014-01-01

    In grasses, variation in seed size and dormancy often results from a seed's position within a dispersal unit. In this paper, I asked whether seed positional effect within a spikelet contributes to ecotypic differentiation between two populations of Avena sterilis having different species range position and associated aridity. I created experimental seed banks in which germination of seeds (florets) having different positions within a spikelet was examined over three years. In addition, two ge...

  10. Key factors affecting seed germination of Copaifera langsdorffii, a Neotropical tree

    Directory of Open Access Journals (Sweden)

    Matheus Lopes Souza

    2015-12-01

    Full Text Available In natural conditions biotic and abiotic factors interact, synergistically affecting seed germination. In this study, we experimentally simulated natural conditions that occur during seed dispersal that can affect the germination of Copaifera langsdorffii. Specifically we evaluated the effect of aril removal by different dispersal agents (birds and ants and fire on germination. The seeds were submitted to the following treatments: Control (seeds placed to germinate with aril intact; Acid (simulation of passage through the digestive tract of a bird; Aril removal (simulation of aril removed by ants; Fire (seeds exposed to fire. Germination percentage and time varied among treatments (X²=89.735, P<0.001; X²=16.225, P<0.001, respectively. None of the control seeds (intact aril germinated. Treatments that simulated dispersal (Acid, Aril removal did not differ in germination percentage, with about 50% of the seeds germinating, however, the acid treatment accelerated seed germination. Fire also had a positive effect on seed germination with about 80% of the seeds germinating. Our results demonstrate the importance of dispersal agents to the population dynamics of C. langsdorffii. Furthermore, the capacity of seeds of C. langsdorffii to tolerate high temperatures is an important attribute for the occurrence of this species in the Cerrado.

  11. Dispersal by cattle of salt-marsh and dune species into salt-marsh and dune communities

    NARCIS (Netherlands)

    Bakker, J. P.; Bravo, L. Galvez; Mouissie, A. M.

    Seed dispersal via ingestion and defecation by large herbivores (endozoochory) plays a potentially important role in structuring plant communities. In the present study we tested whether cattle disperse seeds between different plant communities in a heterogeneous coastal habitat. We surveyed the

  12. Seed trait-mediated selection by rodents affects mutualistic interactions and seedling recruitment of co-occurring tree species.

    Science.gov (United States)

    Zhang, Hongmao; Yan, Chuan; Chang, Gang; Zhang, Zhibin

    2016-02-01

    As mutualists, seed dispersers may significantly affect mutualistic interactions and seedling recruitment of sympatric plants that share similar seed dispersers, but studies are rare. Here, we compared seed dispersal fitness in two co-occurring plant species (Armeniaca sibirica and Amygdalus davidiana) that inhabit warm temperate deciduous forest in northern China. We tested the hypothesis that seed trait-mediated selection by rodents may influence mutualistic interactions with rodents and then seedling establishment of co-occurring plant species. A. davidiana seeds are larger and harder (thick endocarps) than A. sibirica seeds, but they have similar levels of nutrients (crude fat, crude protein), caloric value and tannin. More A. sibirica seedlings are found in the field. Semi-natural enclosure tests indicated that the two seed species were both harvested by the same six rodent species, but that A. sibirica had mutualistic interactions (scatter hoarding) with four rodent species (Apodemus peninsulae, A. agrarius, Sciurotamias davidianus, Tamias sibiricus), and A. davidiana with only one (S. davidianus). Tagged seed dispersal experiments in the field indicated that more A. sibirica seeds were scatter-hoarded by rodents, and more A. sibirica seeds survived to the next spring and became seedlings. A. sibirica seeds derive more benefit from seed dispersal by rodents than A. davidiana seeds, particularly in years with limited seed dispersers, which well explained the higher seedling recruitment of A. sibirica compared with that of A. davidiana under natural conditions. Our results suggest that seed dispersers may play a significant role in seedling recruitment and indirect competition between co-occurring plant species.

  13. Making dispersal syndromes and networks useful in tropical conservation and restoration

    Directory of Open Access Journals (Sweden)

    Henry F. Howe

    2016-04-01

    Full Text Available Dispersal syndromes and networks must be used cautiously in conserving and restoring seed-dispersal processes. In many tropical forests most tree and shrub species require dispersal by animals for local persistence and for migration in response to environmental change. The most important errors to avoid in practical use of both dispersal syndromes (suites of fruit and seed characteristics that attract different dispersal agents and network modules (groups of interacting dispersal agents and plants bearing fruits or seeds that they eat are: (1 assuming that use of fruit resources by fruit-eating animals implies effective seed dispersal; (2 assuming that superficially similar fruits imply equally effective dispersal by similar animals, and (3 assuming that fruit resources at issue support animal populations. This essay explores strengths and weaknesses of uses of dispersal syndromes and disperser networks modules in conservation and restoration. Examples include some that are consistent with expectations from syndrome categorization and some that are not. An unappreciated weakness in using either dispersal syndromes or network modules is that contingent foraging by animals in highly disturbed habitats, now comprising 60%–70% of tropical land biomes, may not resemble foraging choices or consequences in protected closed forests, where most research on tropical seed dispersal is done. General prescriptions for the future include maintaining or creating habitat heterogeneity in largely deforested landscapes where remnant closed forests still exist, and active restoration in landscapes where little heterogeneity remains. In both cases, adaptations of multiple frame-work tree approaches have the best chance of preserving or enhancing populations of animal-dispersed trees and their seed vectors, and in opening migration paths in response to climate change.

  14. Mutualism in a Reduced Gravity Environment (MuRGE)

    Science.gov (United States)

    Haire, Timothy C.

    2010-01-01

    Mutualism in a Reduced Gravity Environment (MuRGE) is a ground research study to determine the feasibility of assessing fungi-plant (Piriformospora indica-Arabidopsis thaliana) interactions in microgravity. Seeds from the plant Arabiddospsis thaliana (At) will be grown in the presence of Piriformospora indica (Pi) an endophytic Sebacinacae family fungus. Pi is capable of colonizing the roots of a wide variety of plant species, including non-mycorrhizal hosts like At, and promoting plant growth similarly to AMF (arbusuclar mychorrizal fungi) unlike most AMF, Pi is not an obligate plant symbiont and can be grown in the absence of a host. In the presence of a suitable plant host, Pi can attach to and colonize root tips. Interaction visualization is accomplished with strong autofluorescence in the roots, followed by root colonization via fungal hyphae, and chlamydospore production. Increased root growth can be observed even before root colonization is detectable. In addition, Pi chlamydospores generated from axenic culture in microgravity will be used to inoculate roots of At grown in 1g to determine the effect of microgravity upon the inherent virulence or beneficial effects. Based on recent reports of increased virulence of S. typhimurium, P. aeruginosa, and S. Pneumoniae in reduced gravity, differences in microbial pathogenic responses and host plant systemic acquired resistance are expected. The focus of this project within MuRGE involved the development P. indica culture media evaluation and microscopy protocol development. High, clean spore harvest yields for the detection of fungi-plant interactions microscopically was the immediate goal of this experiment.

  15. Barley seed aging

    NARCIS (Netherlands)

    Nagel, Manuela; Kodde, Jan; Pistrick, Sibylle; Mascher, Martin; Börner, Andreas; Groot, Steven P.C.

    2016-01-01

    Experimental seed aging approaches intend to mimic seed deterioration processes to achieve a storage interval reduction. Common methods apply higher seed moisture levels and temperatures. In contrast, the “elevated partial pressure of oxygen” (EPPO) approach treats dry seed stored at ambient

  16. Quantum corrections to holographic mutual information

    International Nuclear Information System (INIS)

    Agón, Cesar A.; Faulkner, Thomas

    2016-01-01

    We compute the leading contribution to the mutual information (MI) of two disjoint spheres in the large distance regime for arbitrary conformal field theories (CFT) in any dimension. This is achieved by refining the operator product expansion method introduced by Cardy http://dx.doi.org/10.1088/1751-8113/46/28/285402. For CFTs with holographic duals the leading contribution to the MI at long distances comes from bulk quantum corrections to the Ryu-Takayanagi area formula. According to the FLM proposal http://dx.doi.org/10.1007/JHEP11(2013)074 this equals the bulk MI between the two disjoint regions spanned by the boundary spheres and their corresponding minimal area surfaces. We compute this quantum correction and provide in this way a non-trivial check of the FLM proposal.

  17. Speech Intelligibility Prediction Based on Mutual Information

    DEFF Research Database (Denmark)

    Jensen, Jesper; Taal, Cees H.

    2014-01-01

    a minimum mean-square error (mmse) estimator based on the noisy/processed amplitude. The proposed model predicts that speech intelligibility cannot be improved by any processing of noisy critical-band amplitudes. Furthermore, the proposed intelligibility predictor performs well ( ρ > 0.95) in predicting......This paper deals with the problem of predicting the average intelligibility of noisy and potentially processed speech signals, as observed by a group of normal hearing listeners. We propose a model which performs this prediction based on the hypothesis that intelligibility is monotonically related...... to the mutual information between critical-band amplitude envelopes of the clean signal and the corresponding noisy/processed signal. The resulting intelligibility predictor turns out to be a simple function of the mean-square error (mse) that arises when estimating a clean critical-band amplitude using...

  18. Does the passage of seeds through frugivore gut affect their storage: A case study on the endangered plant Euryodendron excelsum

    OpenAIRE

    Shikang, Shen; Fuqin, Wu; Yuehua, Wang

    2015-01-01

    Plant-frugivore mutualism serves an important function in multiple ecological processes. Although previous studies have highlighted the effect of frugivore gut passage on fresh seed germinability, no study has investigated the effect on seed storage after frugivore gut passage. We used the endangered plant, Euryodendron excelsum, to determine the combined effects of frugivore gut passage and storage conditions on the germination percentage and rate of seeds. In particular, three treatments th...

  19. Danish Mutual Fund Performance - Selectivity, Market Timing and Persistence

    DEFF Research Database (Denmark)

    Christensen, Michael

    Funds under management by Danish mutual funds have increased by 25% annually during the last 10 years and measured per capita Denmark has the third largest mutual fund industry in Europe. This paper provides the first independent performance analysis of Danish mutual funds. We analyse selectivity...... applying a single index model and a multi-factor model, respectively. Furthermore, we analyse the timing ability of the Danish mutual funds pursuing both the quadratic regressions of Treynor and Mazuy (1966) and the option approach suggested by Henriksson and Merton (1981). Finally, we analyse performance...... persistence using parametric as well as non-parametric methodologies. We conclude that in general Danish mutual funds perform neutrally, returns are non-persistent and Danish mutual funds have no timing ability....

  20. Endocarp thickness affects seed removal speed by small rodents in a warm-temperate broad-leafed deciduous forest, China

    Science.gov (United States)

    Zhang, Hongmao; Zhang, Zhibin

    2008-11-01

    Seed traits are important factors affecting seed predation by rodents and thereby the success of recruitment. Seeds of many tree species have hard hulls. These are thought to confer mechanical protection, but the effect of endocarp thickness on seed predation by rodents has not been well investigated. Wild apricot ( Prunus armeniaca), wild peach ( Amygdalus davidiana), cultivated walnut ( Juglans regia), wild walnut ( Juglans mandshurica Maxim) and Liaodong oak ( Quercus liaotungensis) are very common tree species in northwestern Beijing city, China. Their seeds vary greatly in size, endocarp thickness, caloric value and tannin content. This paper aims to study the effects of seed traits on seed removal speed of these five tree species by small rodents in a temperate deciduous forest, with emphasis on the effect of endocarp thickness. The results indicated that speed of removal of seeds released at stations in the field decreased significantly with increasing endocarp thickness. We found no significant correlations between seed removal speed and other seed traits such as seed size, caloric value and tannin content. In seed selection experiments in small cages, Père David's rock squirrel ( Sciurotamias davidianus), a large-bodied, strong-jawed rodent, selected all of the five seed species, and the selection order among the five seed species was determined by endocarp thickness and the ratio of endocarp mass/seed mass. In contrast, the Korean field mouse ( Apodemus peninsulae) and Chinese white-bellied rat ( Niviventer confucianus), with relatively small bodies and weak jaws, preferred to select small seeds like acorns of Q. liaotungensis and seeds of P. armeniaca, indicating that rodent body size is also an important factor affecting food selection based on seed size. These results suggest endocarp thickness significantly reduces seed removal speed by rodents and then negatively affects dispersal fitness of seeds before seed removal of tree species in the study

  1. Modeling the Substrate Skin Effects in Mutual RL Characteristics.,

    Directory of Open Access Journals (Sweden)

    D. de Roest

    2003-12-01

    Full Text Available The goal of this work was to model the influence of the substrateskin effects on the distributed mutual impedance per unit lengthparameters of multiple coupled on-chip interconnects. The proposedanalytic model is based on the frequency-dependent distribution of thecurrent in the silicon substrate and the closed form integrationapproach. It is shown that the calculated frequency-dependentdistributed mutual inductance and the associated mutual resistance arein good agreement with the results obtained from CAD-oriented circuitmodeling technique.

  2. Financial Crisis and Corporate Social Responsible Mutual Fund Flows

    OpenAIRE

    Sitikantha Parida; Zhihong Wang

    2018-01-01

    In this paper, we investigate investment flows into mutual funds that hold more high corporate social responsible stocks (top CSR funds) vs. mutual funds that hold more low corporate social responsible stocks (bottom CSR funds). Using a large sample of equity mutual funds spanning 2003–2012, we find that top CSR funds on average receive about 5% less investment per annum compared to the other funds; whereas bottom CSR funds receive about 5.6% more investments. These relative negative and posi...

  3. Essays on mutual funds, derivatives, and other complex instruments

    OpenAIRE

    Schulte, Dominik

    2016-01-01

    The goal of this dissertation is to analyze the extent to which mutual funds employ derivatives and other complex instruments, such as borrowing of money, short selling, and security lending, and how this influences their performance and risk properties. To carry out this task, a unique dataset containing regulatory data on complex instruments use of mutual funds from the Securities and Exchange Commission (SEC) is employed. Chapter II investigates how equity mutual funds employ derivatives t...

  4. Radiological response of lanthanum guiding seeds in brachytherapy implants; Resposta radiologica de sementes guia de lantanio em implantes braquiterapicos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.S.R.; Machado, E.D.P., E-mail: lais26@globo.com [Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil). Departamento de Engenharia de Materiais; Campos, T.P.R. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Roberto, W.S. [Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil). Departamento de Fisica e Matematica

    2013-08-15

    Ceramic seeds with La-139 incorporated were synthesized to be used as radiological guides in brachytherapy implants. The synthesis was performed based on the sol-gel method. The seeds were subjected to characterization by Scanning Electron Microscopy, X-ray diffraction and Energy-Dispersive X-ray Spectroscopy. Furthermore, the contrast from a radiographic film was evaluated to lanthanum, samarium and holmium seeds. Radiological response on a phantom at different depths with lanthanum seeds and metal seeds was also investigated. Based on the values of contrast, the synthesized lanthanum seeds can be considered efficient as radiological guides when implanted together with pure Ho-165 and Sm-152 seeds. (author)

  5. Intra-specific downsizing of frugivores affects seed germination of fleshy-fruited plant species

    Science.gov (United States)

    Pérez-Méndez, Néstor; Rodríguez, Airam; Nogales, Manuel

    2018-01-01

    The loss of largest-bodied individuals within species of frugivorous animals is one of the major consequences of defaunation. The gradual disappearance of large-bodied frugivores is expected to entail a parallel deterioration in seed dispersal functionality if the remaining smaller-sized individuals are not so effective as seed dispersers. While the multiple impacts of the extinction of large bodied species have been relatively well studied, the impact of intraspecific downsizing (i.e. the extinction of large individuals within species) on seed dispersal has rarely been evaluated. Here we experimentally assessed the impact of body-size reduction in the frugivorous lizard Gallotia galloti (Lacertidae), an endemic species of the Canary Islands, on the seed germination patterns of two fleshy-fruited plant species (Rubia fruticosa and Withania aristata). Seed germination curves and the proportions of germinated seeds were compared for both plant species after being defecated by large-sized individuals and small-sized individuals. The data show that seeds of W. aristata defecated by larger-sized lizards germinated faster and in a higher percentage than those defecated by small-sized lizards, while no differences were found for R. fruticosa seeds. Our results suggest that disappearance of the largest individuals of frugivorous species may impair recruitment of some plant species by worsening seed germination. They also warn us of a potential cryptic loss of seed dispersal functionality on defaunated ecosystems, even when frugivorous species remain abundant.

  6. Mutual inactivation of Notch receptors and ligands facilitates developmental patterning.

    Directory of Open Access Journals (Sweden)

    David Sprinzak

    2011-06-01

    Full Text Available Developmental patterning requires juxtacrine signaling in order to tightly coordinate the fates of neighboring cells. Recent work has shown that Notch and Delta, the canonical metazoan juxtacrine signaling receptor and ligand, mutually inactivate each other in the same cell. This cis-interaction generates mutually exclusive sending and receiving states in individual cells. It generally remains unclear, however, how this mutual inactivation and the resulting switching behavior can impact developmental patterning circuits. Here we address this question using mathematical modeling in the context of two canonical pattern formation processes: boundary formation and lateral inhibition. For boundary formation, in a model motivated by Drosophila wing vein patterning, we find that mutual inactivation allows sharp boundary formation across a broader range of parameters than models lacking mutual inactivation. This model with mutual inactivation also exhibits robustness to correlated gene expression perturbations. For lateral inhibition, we find that mutual inactivation speeds up patterning dynamics, relieves the need for cooperative regulatory interactions, and expands the range of parameter values that permit pattern formation, compared to canonical models. Furthermore, mutual inactivation enables a simple lateral inhibition circuit architecture which requires only a single downstream regulatory step. Both model systems show how mutual inactivation can facilitate robust fine-grained patterning processes that would be difficult to implement without it, by encoding a difference-promoting feedback within the signaling system itself. Together, these results provide a framework for analysis of more complex Notch-dependent developmental systems.

  7. Fruit and seed heteromorphism in the cold desert annual ephemeral Diptychocarpus strictus (Brassicaceae) and possible adaptive significance

    Science.gov (United States)

    Lu, Juanjuan; Tan, Dunyan; Baskin, Jerry M.; Baskin, Carol C.

    2010-01-01

    Background and Aims Diptychocarpus strictus is an annual ephemeral in the cold desert of northwest China that produces heteromorphic fruits and seeds. The primary aims of this study were to characterize the morphology and anatomy of fruits and seeds of this species and compare the role of fruit and seed hetermorphism in dispersal and germination. Methods Shape, size, mass and dispersal of siliques and seeds and the thickness of the mucilage layer on seeds were measured, and the anatomy of siliques and seeds, the role of seed mucilage in water absorption/dehydration, germination and adherence of seeds to soil particles, the role of pericarp of lower siliques in seed dormancy and seed after-ripening and germination phenology were studied using standard procedures. Key Results Plants produce dehiscent upper siliques with a thin pericarp containing seeds with large wings and a thick mucilage layer and indehiscent lower siliques with a thick pericarp containing nearly wingless seeds with a thin mucilage layer. The dispersal ability of seeds from the upper siliques was much greater than that of intact lower siliques. Mucilage increased the amount of water absorbed by seeds and decreased the rate of dehydration. Seeds with a thick mucilage layer adhered to soil particles much better than those with a thin mucilage layer or those from which mucilage had been removed. Fresh seeds were physiologically dormant and after-ripened during summer. Non-dormant seeds germinated to high percentages in light and in darkness. Germination of seeds from upper siliques is delayed until spring primarily by drought in summer and autumn, whereas the thick, indehiscent pericarp prevents germination for >1 year of seeds retained in lower siliques. Conclusions The life cycle of D. strictus is morphologically and physiologically adapted to the cold desert environment in time and space via a combination of characters associated with fruit and seed heteromorphism. PMID:20348559

  8. Genetics of dispersal

    Science.gov (United States)

    Bocedi, Greta; Cote, Julien; Legrand, Delphine; Guillaume, Frédéric; Wheat, Christopher W.; Fronhofer, Emanuel A.; Garcia, Cristina; Henry, Roslyn; Husby, Arild; Baguette, Michel; Bonte, Dries; Coulon, Aurélie; Kokko, Hanna; Matthysen, Erik; Niitepõld, Kristjan; Nonaka, Etsuko; Stevens, Virginie M.; Travis, Justin M. J.; Donohue, Kathleen; Bullock, James M.; del Mar Delgado, Maria

    2017-01-01

    ABSTRACT Dispersal is a process of central importance for the ecological and evolutionary dynamics of populations and communities, because of its diverse consequences for gene flow and demography. It is subject to evolutionary change, which begs the question, what is the genetic basis of this potentially complex trait? To address this question, we (i) review the empirical literature on the genetic basis of dispersal, (ii) explore how theoretical investigations of the evolution of dispersal have represented the genetics of dispersal, and (iii) discuss how the genetic basis of dispersal influences theoretical predictions of the evolution of dispersal and potential consequences. Dispersal has a detectable genetic basis in many organisms, from bacteria to plants and animals. Generally, there is evidence for significant genetic variation for dispersal or dispersal‐related phenotypes or evidence for the micro‐evolution of dispersal in natural populations. Dispersal is typically the outcome of several interacting traits, and this complexity is reflected in its genetic architecture: while some genes of moderate to large effect can influence certain aspects of dispersal, dispersal traits are typically polygenic. Correlations among dispersal traits as well as between dispersal traits and other traits under selection are common, and the genetic basis of dispersal can be highly environment‐dependent. By contrast, models have historically considered a highly simplified genetic architecture of dispersal. It is only recently that models have started to consider multiple loci influencing dispersal, as well as non‐additive effects such as dominance and epistasis, showing that the genetic basis of dispersal can influence evolutionary rates and outcomes, especially under non‐equilibrium conditions. For example, the number of loci controlling dispersal can influence projected rates of dispersal evolution during range shifts and corresponding demographic impacts

  9. Aphid Heritable Symbiont Exploits Defensive Mutualism.

    Science.gov (United States)

    Doremus, Matthew R; Oliver, Kerry M

    2017-04-15

    Insects and other animals commonly form symbioses with heritable bacteria, which can exert large influences on host biology and ecology. The pea aphid, Acyrthosiphon pisum , is a model for studying effects of infection with heritable facultative symbionts (HFS), and each of its seven common HFS species has been reported to provide resistance to biotic or abiotic stresses. However, one common HFS, called X-type, rarely occurs as a single infection in field populations and instead typically superinfects individual aphids with Hamiltonella defensa , another HFS that protects aphids against attack by parasitic wasps. Using experimental aphid lines comprised of all possible infection combinations in a uniform aphid genotype, we investigated whether the most common strain of X-type provides any of the established benefits associated with aphid HFS as a single infection or superinfection with H. defensa We found that X-type does not confer protection to any tested threats, including parasitoid wasps, fungal pathogens, or thermal stress. Instead, component fitness assays identified large costs associated with X-type infection, costs which were ameliorated in superinfected aphids. Together these findings suggest that X-type exploits the aphid/ H. defensa mutualism and is maintained primarily as a superinfection by "hitchhiking" via the mutualistic benefits provided by another HFS. Exploitative symbionts potentially restrict the functions and distributions of mutualistic symbioses with effects that extend to other community members. IMPORTANCE Maternally transmitted bacterial symbionts are widespread and can have major impacts on the biology of arthropods, including insects of medical and agricultural importance. Given that host fitness and symbiont fitness are tightly linked, inherited symbionts can spread within host populations by providing beneficial services. Many insects, however, are frequently infected with multiple heritable symbiont species, providing potential

  10. Patterns and mechanisms of dispersal in a keystone seagrass species.

    Science.gov (United States)

    Jahnke, Marlene; Christensen, Asbjørn; Micu, Dragos; Milchakova, Nataliya; Sezgin, Murat; Todorova, Valentina; Strungaru, Stefan; Procaccini, Gabriele

    2016-06-01

    Mechanisms and vectors of long-distance dispersal remain unknown for many coastal benthic species, including plants. Indications for the possibility for long-distance dispersal come from dispersal modelling and from genetic assessments, but have rarely been assessed with both methods. To this end, we assessed dispersal of the seagrass Zostera noltei, an important foundation species of the coastal zone. We investigate whether small scale seed dispersal and long-distance propagule dispersal do play a role for meta-population dynamics, using both genetic assessments based on eight microsatellite markers and physical modelling of ocean currents. Such assessments enhance our understanding of the biology and population dynamics of an important coastal foundation species. They are relevant for large scale conservation strategies as they give insights in the maintenance of genetic diversity and connectivity that may enhance resilience and resistance to stresses associated with seagrass loss. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Grounding Animal Rights in Mutual Advantage Contractarianism

    Directory of Open Access Journals (Sweden)

    Matthew Taylor

    2014-09-01

    Full Text Available Contrary to critics and advocates of contractarianism alike, I argue that mutual advantage contractarianism entails rights and protections for animals. In section one I outline the criteria that must be met in order for an individual to qualify for moral rights on the contractarian view. I then introduce an alternative form of ‘rights,’ which I call ‘protectorate status,’ from which an individual can receive protections indirectly. In section two I suggest guidelines for assigning animal rights based on two ways of categorizing animals. On the basis of the categorization according to benefit derived, I argue that animals used for companionship, security, hunting assistance, transportation, entertainment, medical service, nourishment, or clothing will tend to qualify for basic rights against starvation, predation, and disease. On the basis of the categorization according to species, I argue that, on top of the basic rights above, dogs tend to qualify for rights against abuse, and against frivolous medical experimentation, as well as further negotiated rights. Cows have the basic rights against starvation, predation, and disease, but squirrels and bears have no rights. In section three I argue that some animals qualify for protectorate status, which would establish various protections for different animals, but would also generally prohibit cruelty towards animals.

  12. Mutualism between tree shrews and pitcher plants

    Science.gov (United States)

    Moran, Jonathan A; Chin, Lijin

    2010-01-01

    Three species of Nepenthes pitcher plants from Borneo engage in a mutualistic interaction with mountain tree shrews, the basis of which is the exchange of nutritional resources. The plants produce modified “toilet pitchers” that produce copious amounts of exudates, the latter serving as a food source for tree shrews. The exudates are only accessible to the tree shrews when they position their hindquarters over the pitcher orifice. Tree shrews mark valuable resources with feces and regularly defecate into the pitchers when they visit them to feed. Feces represent a valuable source of nitrogen for these Nepenthes species, but there are many facets of the mutualism that are yet to be investigated. These include, but are not limited to, seasonal variation in exudate production rates by the plants,