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Sample records for sand lizards lacerta

  1. UV-deprived coloration reduces success in mate acquisition in male sand lizards (Lacerta agilis.

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    Mats Olsson

    Full Text Available BACKGROUND: Recent work on animal signals has revealed a wide occurrence of UV signals in tetrapods, in particular birds, but also in lizards (and perhaps other Squamate reptiles. Our previous work on the Swedish sand lizard (Lacerta agilis has verified, both in correlative selection analyses in the wild and with laboratory and field experiments, the importance of the green 'badge' on the body sides of adult males for securing mating opportunities, probably mostly through deterring rival males rather than attracting females. The role of UV in communication has, however, never been examined. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that when measured immediately after spring skin shedding, there is also signaling in the UV. By UV-depriving the signal (reflectance with sun block chemicals fixated with permeable, harmless spray dressing, we show that males in the control group (spray dressing only had significantly higher success in mate acquisition than UV-deprived males. CONCLUSIONS/SIGNIFICANCE: These results suggest that at least two colour traits in sand lizards, badge area and UV, contribute to rival deterrence and/or female choice on UV characters, which elevates success in mate acquisition in UV intact male sand lizards.

  2. Anaplasmataceae and Borrelia burgdorferi sensu lato in the sand lizard Lacerta agilis and co-infection of these bacteria in hosted Ixodes ricinus ticks

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    Ekner Anna

    2011-09-01

    Full Text Available Abstract Background Anaplasmataceae and Borrelia burgdorferi s.l. are important tick-borne bacteria maintained in nature by transmission between ticks and vertebrate hosts. However, the potential role of lizards as hosts has not been sufficiently studied. Results The current study showed that 23 of 171 examined sand lizards Lacerta agilis were PCR positive for Anaplasmataceae. The nucleotide sequences of the several selected PCR products showed 100% homology with Anaplasma spp. found in Ixodes ricinus collected in Tunisia and Morocco (AY672415 - AY672420. 1.2% of lizard collar scale samples were PCR positive for B. lusitaniae. In addition, 12 of 290 examined I. ricinus were PCR positive for B. burgdorferi s.l. and 82 were PCR positive for Anaplasmatacea. The number of ticks per lizard and the number of ticks PCR positive for both microorganisms per lizard were strongly correlated. Moreover, we found a significant correlation between numbers of ticks infected with Anaplasmataceae and with B. burgdorferi s.l. living on the same lizard. However, there was no significant correlation between detection of both bacteria in the same tick. Conclusions To the best of our knowledge, this is the first report of Anaplasmataceae DNA and additionally the second report of B. burgdorferi s.l DNA detection in the sand lizard.

  3. Identification of the linkage group of the Z sex chromosomes of the sand lizard (Lacerta agilis, Lacertidae) and elucidation of karyotype evolution in lacertid lizards.

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    Srikulnath, Kornsorn; Matsubara, Kazumi; Uno, Yoshinobu; Nishida, Chizuko; Olsson, Mats; Matsuda, Yoichi

    2014-12-01

    The sand lizard (Lacerta agilis, Lacertidae) has a chromosome number of 2n = 38, with 17 pairs of acrocentric chromosomes, one pair of microchromosomes, a large acrocentric Z chromosome, and a micro-W chromosome. To investigate the process of karyotype evolution in L. agilis, we performed chromosome banding and fluorescent in situ hybridization for gene mapping and constructed a cytogenetic map with 86 functional genes. Chromosome banding revealed that the Z chromosome is the fifth largest chromosome. The cytogenetic map revealed homology of the L. agilis Z chromosome with chicken chromosomes 6 and 9. Comparison of the L. agilis cytogenetic map with those of four Toxicofera species with many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) showed highly conserved linkage homology of L. agilis chromosomes (LAG) 1, 2, 3, 4, 5(Z), 7, 8, 9, and 10 with macrochromosomes and/or macrochromosome segments of the four Toxicofera species. Most of the genes located on the microchromosomes of Toxicofera were localized to LAG6, small acrocentric chromosomes (LAG11-18), and a microchromosome (LAG19) in L. agilis. These results suggest that the L. agilis karyotype resulted from frequent fusions of microchromosomes, which occurred in the ancestral karyotype of Toxicofera and led to the disappearance of microchromosomes and the appearance of many small macrochromosomes.

  4. Selection and constraints on offspring size-number trade-offs in sand lizards (Lacerta agilis).

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    Ljungström, G; Stjernstedt, M; Wapstra, E; Olsson, M

    2016-05-01

    The trade-off between offspring size and number is a central component of life-history theory, postulating that larger investment into offspring size inevitably decreases offspring number. This trade-off is generally discussed in terms of genetic, physiological or morphological constraints; however, as among-individual differences can mask individual trade-offs, the underlying mechanisms may be difficult to reveal. In this study, we use multivariate analyses to investigate whether there is a trade-off between offspring size and number in a population of sand lizards by separating among- and within-individual patterns using a 15-year data set collected in the wild. We also explore the ecological and evolutionary causes and consequences of this trade-off by investigating how a female's resource (condition)- vs. age-related size (snout-vent length) influences her investment into offspring size vs. number (OSN), whether these traits are heritable and under selection and whether the OSN trade-off has a genetic component. We found a negative correlation between offspring size and number within individual females and physical constraints (size of body cavity) appear to limit the number of eggs that a female can produce. This suggests that the OSN trade-off occurs due to resource constraints as a female continues to grow throughout life and, thus, produces larger clutches. In contrast to the assumptions of classic OSN theory, we did not detect selection on offspring size; however, there was directional selection for larger clutch sizes. The repeatabilities of both offspring size and number were low and we did not detect any additive genetic variance in either trait. This could be due to strong selection (past or current) on these life-history traits, or to insufficient statistical power to detect significant additive genetic effects. Overall, the findings of this study are an important illustration of how analyses of within-individual patterns can reveal trade-offs and

  5. No Interstitial Telomeres on Autosomes but Remarkable Amplification of Telomeric Repeats on the W Sex Chromosome in the Sand Lizard (Lacerta agilis).

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    Matsubara, Kazumi; Uno, Yoshinobu; Srikulnath, Kornsorn; Matsuda, Yoichi; Miller, Emily; Olsson, Mats

    2015-01-01

    Telomeres are repeat (TTAGGG) n sequences that form terminal ends of chromosomes and have several functions, such as protecting the coding DNA from erosion at mitosis. Due to chromosomal rearrangements through evolutionary history (e.g., inversions and fusions), telomeric sequences are also found between the centromere and the terminal ends (i.e., at interstitial telomeric sites, ITSs). ITS telomere sequences have been implicated in heritable disease caused by genomic instability of ITS polymorphic variants, both with respect to copy number and sequence. In the sand lizard (Lacerta agilis), we have shown that telomere length is predictive of lifetime fitness in females but not males. To assess whether this sex specific fitness effect could be traced to ITSs differences, we mapped (TTAGGG) n sequences using fluorescence in situ hybridization in fibroblast cells cultured from 4 specimens of known sex. No ITSs could be found on autosomes in either sex. However, females have heterogametic sex chromosomes in sand lizards (ZW, 2n = 38) and the female W chromosome showed degeneration and remarkable (TTAGGG) n amplification, which was absent in the Z chromosomes. This work warrants further research on sex chromosome content, in particular of the degenerate W chromosome, and links to female fitness in sand lizards.

  6. Ultrastructural features of the differentiating thyroid primordium in the sand lizard (Lacerta agilis L.) from the differentiation of the cellular cords to the formation of the follicular lumen.

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    Rupik, Weronika; Kowalska, Magdalena; Swadźba, Elwira; Maślak, Robert

    2016-04-01

    The differentiation of the thyroid primordium of lacertilian species is poorly understood. The present study reports on the ultrastructural analysis of the developing thyroid primordium in the sand lizard (Lacerta agilis) during the early stages of differentiation. The early thyroid primordium of sand lizard embryos was composed of cellular cords that contained single cells with a giant lipid droplet, which were eliminated by specific autophagy (lipophagy). The follicular lumens at the periphery of the primordium differentiated even before the division of the cellular cords. When the single cells within the cords started to die through paraptosis, the adjacent cells started to polarise and junctional complexes began to form around them. After polarisation and clearing up after the formation of the lumens, the cellular cords divided into definitive follicles. The cellular cords in the central part of the primordium started to differentiate later than those at the periphery. The cellular cords divided into presumptive follicles first and only later differentiated into definitive follicles. During this process, a population of centrally located cells was removed through apoptosis to form the lumen. Although the follicular lumen in sand lizard embryos is differentiated by cavitation similar to that in the grass snake, there were very important differences during the early stages of the differentiation of the cellular cords and the formation of the thyroid follicles.

  7. Age and growth of the sand lizards (Lacerta agilis from a high Alpine population of north-western Italy

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    Fabio M. Guarino

    2010-07-01

    Full Text Available We studied growth and longevity of Lacerta agilis from a sample (34 adults and 2 small-sized juveniles of a population living at high altitude in north-western Italy using skeletochronological method. Snout vent length (SVL mean of males did not significantly differ from that of females although the latter were in average bigger (SVL ± SD, males: 69.3 ± 7.1 mm, n = 11; females: 73.9 ± 9.7 mm, n = 22; Mann-Whitney U-test, U = 1.76, P = 0.077. Age ranged from 2 to 4 years (mean age ± SD = 2.3 ± 0.2 in males and from 2 to 3 years in females (mean age ± SD = 2.59 ± 0.5 years. Age mean did not significantly differ between the sexes (Mann-Whitney U-test, U = 1.35, P = 0.174. The two juveniles were 30 and 32 mm in SVL and both were 1-2 months old. In both sexes, a significant positive correlation between SVL and age was recorded although weakly significant for males (Spearman’s correlation coefficient, males: rs = 0.70, P = 0.05; females: rs = 0.75, P < 0.001. Von Bertalanffy growth curves well fitted to the relationships between age and SVL and showed a different profile between males (asymptotics size, SVLmax = 81.9 mm; growth coefficient, k = 0.63 and females (SVLmax = 100 mm; k = 0.40. Results indicate that individuals of L. agilis studied by us are short-living when compared with other populations of the same species.

  8. Sand swimming lizard: sandfish

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    Maladen, Ryan D; Kamor, Adam; Goldman, Daniel I

    2009-01-01

    We use high-speed x-ray imaging to reveal how a small (~10cm) desert dwelling lizard, the sandfish (Scincus scincus), swims within a granular medium [1]. On the surface, the lizard uses a standard diagonal gait, but once below the surface, the organism no longer uses limbs for propulsion. Instead it propagates a large amplitude single period sinusoidal traveling wave down its body and tail to propel itself at speeds up to ~1.5 body-length/sec. Motivated by these experiments we study a numerical model of the sandfish as it swims within a validated soft sphere Molecular Dynamics granular media simulation. We use this model as a tool to understand dynamics like flow fields and forces generated as the animal swims within the granular media. [1] Maladen, R.D. and Ding, Y. and Li, C. and Goldman, D.I., Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard, Science, 325, 314, 2009

  9. Association of Mc1r variants with ecologically relevant phenotypes in the European ocellated lizard, Lacerta lepida

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    Nunes, V. L.; Miraldo, A.; Beaumont, M. A.

    2011-01-01

    range of vertebrate taxa, was assessed in European ocellated lizards (Lacerta lepida) to search for associations with melanin-based colour phenotypes. Lacerta lepida subspecies' distribution is associated with the three major bio-climatic regions in the Iberian Peninsula. A nonconserved and derived...

  10. The importance of habitat resistance for movement decisions in the common lizard, Lacerta vivipara

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    Zajitschek Susanne RK

    2012-07-01

    Full Text Available Abstract Background Movement behaviour can be influenced by a multitude of biotic and abiotic factors. Here, we investigate the speed of movement in relation to environmental and individual phenotypic properties in subadult common lizards (Lacerta vivipara. We aim to disentangle the importance of substrate, cover, humidity, basking opportunity and individual phenotype on moving tendencies in 12 treatment combinations, at which each lizard was tested. Results We find that movement behaviour depends on the starting conditions, the physical properties of the dispersal corridor, and on the individuals’ phenotype. Specifically, the presence of cover and substrate providing suitable traction in the corridor had positive effects on individual movement decisions. Additionally, we find high phenotypic variation in the propensity to move dependent on the presence of cover. Individual back patterns also strongly affected movement decisions in interaction with the physical properties of the dispersal corridor. Conclusions Our results highlight the importance of understanding the habitat resistance for movement patterns, with humid habitats with covering vegetation providing the best conditions to initiate movement in the common lizard. In addition, population effects, differences in back pattern phenotype and individual plasticity were identified as key parameters influencing movement behaviour.

  11. The alteration of proportion of different lizard species compared to each other at The Great Pasture of Hajdubagos

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    Antal, Zsuzsanna

    2006-01-01

    Three different lizard species can be found at the great pasture of Hajúbagos. These are the balkan or crimean wall lizard (Podarcis taurica), the sand lizard (Lacerta agilis) and the green lizard (Lacerta viridis). All of them are protected by law in Hungary but while sand lizard and green lizard is common all over the country, the amount of the balkan wall lizard is decreasing. The main cause of this regrettable possession is the habitat degradation and thus habitat loss. Namely balkan wall...

  12. Ultraviolet nuptial colour determines fight success in male European green lizards (Lacerta viridis).

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    Bajer, Katalin; Molnár, Orsolya; Török, János; Herczeg, Gábor

    2011-12-23

    Animal communication through colour signals is a central theme in sexual selection. Structural colours can be just as costly and honest signals as pigment-based colours. Ultraviolet (UV) is a structural colour that can be important both in intrasexual competition and mate choice. However, it is still unknown if a UV signal alone can determine the outcome of male-male fights. European green lizard (Lacerta viridis) males develop a nuptial throat coloration with a strong UV component. Among males differing only in their manipulated UV colour, females prefer males with higher UV. Here, we experimentally decreased the UV coloration of randomly chosen males from otherwise similar male pairs to test the hypothesis that a difference in UV colour alone can affect fight success during male-male competition. Our results fully supported the hypotheses: in almost 90 per cent of the contests the male with reduced UV lost the fight. Our results show that UV can be an important signal, affecting both female mate choice and determining male fight success.

  13. Temporal distributions, habitat associations and behaviour of the green lizard (Lacerta bilineata and wall lizard (Podarcis muralis on roads in a fragmented landscape in Western France

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    Roger Meek

    2014-12-01

    Full Text Available Observations of the green lizard (Lacerta bilineata and wall lizard (Podarcis muralis on roads in Western France indicated that basking close to the road edge was the predominant activity in L. bilineata but P. muralis mostly foraged. Spatial locations of road mortalities in both species reflected this with the median distances from the road edge greater in P. muralis. Temporal differences in road presence, based on mortality counts and those of live lizards, indicated significantly more lizards were present on roads during late summer and autumn, especially in P. muralis. A significant correlation was found between the monthly presence of live lizards and monthly road mortalities in P. muralis (r = 0.73 but not in L. bilineata (r = 0.64.  Numbers of L. bilineata found on roads bisecting low-density urban areas and roads bordered by hedgerows were higher than expected in relation to the occurrence of these habitats at roadsides. In P. muralis higher than expected numbers were found alongside low-density urban areas and roads bisecting woodland. Generally both species were less commonly seen on roads alongside agricultural areas with no hedgerow border.

  14. Mating order-dependent female mate choice in the polygynandrous common lizard Lacerta vivipara.

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    Fitze, Patrick S; Cote, Julien; Clobert, Jean

    2010-02-01

    Recent studies indicate that directional female mate choice and order-dependent female mate choice importantly contribute to non-random mating patterns. In species where females prefer larger sized males, disentangling different hypotheses leading to non-random mating patterns is especially difficult, given that male size usually correlates with behaviours that may lead to non-random mating (e.g. size-dependent emergence from hibernation, male fighting ability). Here we investigate female mate choice and order-dependent female mate choice in the polygynandrous common lizard (Lacerta vivipara). By sequentially presenting males in random order to females, we exclude non-random mating patterns potentially arising due to intra-sexual selection (e.g. male-male competition), trait-dependent encounter probabilities, trait-dependent conspicuousness, or trait-dependent emergence from hibernation. To test for order-dependent female mate choice we investigate whether the previous mating history affects female choice. We show that body size and body condition of the male with which a female mated for the first time were bigger and better, respectively, than the average body size and body condition of the rejected males. There was a negative correlation between body sizes of first and second copulating males. This indicates that female mate choice is dependent on the previous mating history and it shows that the female's choice criteria are non-static, i.e. non-directional. Our study therefore suggests that context-dependent female mate choice may not only arise due to genotype-environment interactions, but also due to other female mating strategies, i.e. order-dependent mate choice. Thus context-dependent female mate choice might be more frequent than previously thought.

  15. Spotted fever group rickettsiae detected in immature stages of ticks parasitizing on Iberian endemic lizard Lacerta schreiberi Bedriaga, 1878.

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    Kubelová, Michaela; Papoušek, Ivo; Bělohlávek, Tomáš; de Bellocq, Joëlle Goüy; Baird, Stuart J E; Široký, Pavel

    2015-09-01

    Spotted fever rickettsioses are tick-borne diseases of growing public health concern. The prevalence of rickettsia-infected ticks and their ability to parasitize humans significantly influence the risk of human infection. Altogether 466 Ixodes ricinus ticks (428 nymphs and 38 larvae) collected from 73 Lacerta schreiberi lizards were examined by PCR targeting the citrate synthetase gene gltA for the presence of Rickettsia spp. Rickettsial DNA was detected in 47% of nymphs and 31.6% of larvae. They were subsequently subjected to a second PCR reaction using primers derived from the outer membrane protein rOmpA encoding gene (ompA) to detect spotted fever group rickettsiae (SFG). This analysis shows that 41.4% of nymphs and 7.9% of larvae collected from the lizards contain DNA of SFG rickettsiae. Sequencing of 43 randomly selected samples revealed two different haplotypes, both closely related to R. monacensis (39 and 4 samples, respectively). The remaining ompA negative Rickettsia spp. samples were determined to be R. helvetica based on sequencing of ompB and gltA fragments. Our results indicate that the role of Iberian endemic lizard L. schreiberi and its ectoparasites in the ecology and epidemiology of zoonotic SFG rickettsioses may be appreciable.

  16. [Increased variability of (TCC)n microsatelline loci in populations of the parthenogenetic lizard Lacerta unisexualis Darevsky].

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    Ryskov, A P; Kan, N G; Martirosian, I A; Darevskiĭ, I S; Danielian, F D; Petrosian, V G; Tokarskaia, O N

    2000-11-01

    In four isolated populations of parthenogenetic Caucasian rock lizard Lacerta unisexualis, variability of (TCC)n loci was examined using multilocus DNA fingerprinting. Unexpectedly high variability of (TCC)n microsatellites was found in all four populations. The mean similarity index was 0.825, which is higher than similarity estimates obtained for other mini- and microsatellite loci in L. unisexualis and parthenogenetic species L. dahli and L. armeniaca studied earlier. The high variation level of (TCC)n loci was shown to be at least partially associated with the presence of a diverged (TCC)n sequence fraction in the L. unisexualis genome. Mutations at some other genetically unstable (TCC)n loci may cause their structural diversity in populations of L. unisexualis.

  17. Iridophores and not carotenoids account for chromatic variation of carotenoid-based coloration in common lizards (Lacerta vivipara).

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    San-Jose, Luis M; Granado-Lorencio, Fernando; Sinervo, Barry; Fitze, Patrick S

    2013-03-01

    Abstract Carotenoids typically need reflective background components to shine. Such components, iridophores, leucophores, and keratin- and collagen-derived structures, are generally assumed to show no or little environmental variability. Here, we investigate the origin of environmentally induced variation in the carotenoid-based ventral coloration of male common lizards (Lacerta vivipara) by investigating the effects of dietary carotenoids and corticosterone on both carotenoid- and background-related reflectance. We observed a general negative chromatic change that was prevented by β-carotene supplementation. However, chromatic changes did not result from changes in carotenoid-related reflectance or skin carotenoid content but from changes in background-related reflectance that may have been mediated by vitamin A1. An in vitro experiment showed that the encountered chromatic changes most likely resulted from changes in iridophore reflectance. Our findings demonstrate that chromatic variation in carotenoid-based ornaments may not exclusively reflect differences in integumentary carotenoid content and, hence, in qualities linked to carotenoid deposition (e.g., foraging ability, immune response, or antioxidant capacity). Moreover, skin carotenoid content and carotenoid-related reflectance were related to male color polymorphism, suggesting that carotenoid-based coloration of male common lizards is a multicomponent signal, with iridophores reflecting environmental conditions and carotenoids reflecting genetically based color morphs.

  18. European green lizard (Lacerta viridis) personalities: Linking behavioural types to ecologically relevant traits at different ontogenetic stages.

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    Bajer, Katalin; Horváth, Gergely; Molnár, Orsolya; Török, János; Garamszegi, László Zsolt; Herczeg, Gábor

    2015-02-01

    Consistent individual differences within (animal personality) and across (behavioural syndrome) behaviours became well recognized during the past decade. Nevertheless, our knowledge about the evolutionary and developmental mechanisms behind the phenomena is still incomplete. Here, we explored if risk-taking and exploration were consistent and linked to different ecologically relevant traits in wild-caught adult male European green lizards (Lacerta viridis) and in their 2-3 weeks old laboratory-reared offspring. Both adults and juveniles displayed animal personality, consistency being higher in juveniles. We found correlation between risk-taking and exploration (suggestive of a behavioural syndrome) only in adults. Juveniles were more explorative than adults. Large or ectoparasite-free adult males were more explorative than small or parasitized males. Juvenile females tended to be more risk-taking than males. Behaviour of fathers and their offspring did not correlate. We conclude that European green lizards show high behavioural consistency and age is an important determinant of its strength and links to traits likely affecting fitness.

  19. In hot pursuit: fluctuating mating system and sexual selection in sand lizards.

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    Olsson, Mats; Wapstra, Erik; Schwartz, Tonia; Madsen, Thomas; Ujvari, Beata; Uller, Tobias

    2011-02-01

    A changing climate is expected to have profound effects on many aspects of ectotherm biology. We report on a decade-long study of free-ranging sand lizards (Lacerta agilis), exposed to an increasing mean mating season temperature and with known operational sex ratios. We assessed year-to-year variation in sexual selection on body size and postcopulatory sperm competition and cryptic female choice. Higher temperature was not linked to strength of sexual selection on body mass, but operational sex ratio (more males) did increase the strength of sexual selection on body size. Elevated temperature increased mating rate and number of sires per clutch with positive effects on offspring fitness. In years when the "quality" of a female's partners was more variable (in standard errors of a male sexual ornament), clutches showed less multiple paternity. This agrees with prior laboratory trials in which females exercised stronger cryptic female choice when male quality varied more. An increased number of sires contributing to within-clutch paternity decreased the risk of having malformed offspring. Ultimately, such variation may contribute to highly dynamic and shifting selection mosaics in the wild, with potential implications for the evolutionary ecology of mating systems and population responses to rapidly changing environmental conditions.

  20. Undulatory swimming in sand: subsurface locomotion of the sandfish lizard.

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    Maladen, Ryan D; Ding, Yang; Li, Chen; Goldman, Daniel I

    2009-07-17

    The desert-dwelling sandfish (Scincus scincus) moves within dry sand, a material that displays solid and fluidlike behavior. High-speed x-ray imaging shows that below the surface, the lizard no longer uses limbs for propulsion but generates thrust to overcome drag by propagating an undulatory traveling wave down the body. Although viscous hydrodynamics can predict swimming speed in fluids such as water, an equivalent theory for granular drag is not available. To predict sandfish swimming speed, we developed an empirical model by measuring granular drag force on a small cylinder oriented at different angles relative to the displacement direction and summing these forces over the animal movement profile. The agreement between model and experiment implies that the noninertial swimming occurs in a frictional fluid.

  1. Adaptation to life in aeolian sand: how the sandfish lizard, Scincus scincus, prevents sand particles from entering its lungs

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    Stadler, Anna T.; Vihar, Boštjan; Günther, Mathias; Huemer, Michaela; Riedl, Martin; Shamiyeh, Stephanie; Mayrhofer, Bernhard; Böhme, Wolfgang; Baumgartner, Werner

    2016-01-01

    ABSTRACT The sandfish lizard, Scincus scincus (Squamata: Scincidae), spends nearly its whole life in aeolian sand and only comes to the surface for foraging, defecating and mating. It is not yet understood how the animal can respire without sand particles entering its respiratory organs when buried under thick layers of sand. In this work, we integrated biological studies, computational calculations and physical experiments to understand this phenomenon. We present a 3D model of the upper res...

  2. Ground resistance influences lizard burial in dry and wet sand

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    Sharpe, Sarah; Kuckuk, Robyn; Goldman, Daniel

    2012-11-01

    Many terrestrial animals move within soil in which water content can vary, and little is known about how water content affects locomotor performance. To investigate the effect of water content on burial, we created controlled dry and wet substrates. We used 0.3 mm glass particles and varied water content W, the mass of water to mass of dry loosely packed sand. Drag force on a submerged 1.6 cm diameter rod increased by a factor of 4 as W increased from 0 to 0.03, after which force increases were small. Drag force in wet media periodically fluctuated with time and corresponded with surface fracturing. We characterized how W affected burial performance and strategy of a generalist burrower, the ocellated skink lizard (Chalcides ocellatus). High speed x-ray imaging was used to measure head, body and limb kinematics in substrates with W= 0 and W= 0.03. In both states during burial the body was maintained in a curved posture and the animal moved using a start-stop motion. During movement, the head oscillated and the forelimb on the convex side of the body was used to push the animal forward. Both speed and angular excursion of the head oscillation decreased in the W= 0.03 state. The differences in locomotion were attributed to the changing resistance force within the media.

  3. Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard

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    Ryan D. Maladen; Yang Ding; Chen Li; Daniel I. Goldman

    2009-01-01

    .... High-speed x-ray imaging shows that below the surface, the lizard no longer uses limbs for propulsion but generates thrust to overcome drag by propagating an undulatory traveling wave down the body...

  4. Numts help to reconstruct the demographic history of the ocellated lizard (Lacerta lepida) in a secondary contact zone

    DEFF Research Database (Denmark)

    Miraldo, Andreia; Hewitt, Godfrey M; Dear, Paul H

    2012-01-01

    In northwestern Iberia, two largely allopatric Lacerta lepida mitochondrial lineages occur, L5 occurring to the south of Douro River and L3 to the north, with a zone of putative secondary contact in the region of the Douro River valley. Cytochrome b sequence chromatograms with polymorphisms...... of secondary contact between the lineages. The additional incidence of these numts to the north of the putative contact zone is consistent with an earlier postglacial northward range expansion of L5, preceding that of L3. We show that genetic exchange between the lineages responsible for the origin...... of these numts in L3 after secondary contact occurred prior to, or coincident with, the northward expansion of L3. This study shows that, in the context of phylogeographic analysis, numts can provide evidence for past demographic events and can be useful tools for the reconstruction of complex evolutionary...

  5. Medical cautery units as a permanent and non-invasive method of marking lizards

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    Anna Ekner

    2011-12-01

    Full Text Available The identification of previously captured individuals is essential for a wide variety of ecological and behavioural studies. A lot of different methods are used for marking lizards, however they have many drawbacks. In presented study we used heat-branding method, using pen-like medical cautery units, previously employed to successfully mark other lizard species and snakes. The technique is permanent, readable and harmless for lizards, as well quick and easy. In 2009 we marked 111 individuals of sand lizard, Lacerta agilis. Next year we caught 88 lizards, 17 of them were re-captured. Among these re-captured lizards, five were caught after 26.8 (± 16.3 days (means in the same year and 12 after 308.8 (± 64.3 days (means in the next year. Recaptured individuals were still unambiguously recognisable.

  6. Role of sand lizards in the ecology of Lyme and other tick-borne diseases in the Netherlands

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    Spitzen - van der Sluijs Annemarieke

    2010-05-01

    Full Text Available Abstract Background Lizards are considered zooprophylactic for almost all Borrelia burgdorferi species, and act as dilution hosts in parts of North America. Whether European lizards significantly reduce the ability of B. burgdorferi to maintain itself in enzootic cycles, and consequently decrease the infection rate of Ixodes ricinus ticks for B. burgdorferi and other tick-borne pathogens in Western Europe is not clear. Results Ticks were collected from sand lizards, their habitat (heath and from the adjacent forest. DNA of tick-borne pathogens was detected by PCR followed by reverse line blotting. Tick densities were measured at all four locations by blanket dragging. Nymphs and adult ticks collected from lizards had a significantly lower (1.4% prevalence of B. burgdorferi sensu lato, compared to questing ticks in heath (24% or forest (19%. The prevalence of Rickettsia helvetica was significantly higher in ticks from lizards (19% than those from woodland (10% whereas neither was significantly different from the prevalence in ticks from heather (15%. The prevalence of Anaplasma and Ehrlichia spp in heather (12% and forest (14% were comparable, but significantly lower in ticks from sand lizards (5.4%. The prevalence of Babesia spp in ticks varied between 0 and 5.3%. Tick load of lizards ranged from 1 - 16. Tick densities were ~ 5-fold lower in the heather areas than in woodlands at all four sites. Conclusions Despite their apparent low reservoir competence, the presence of sand lizards had insignificant impact on the B. burgdorferi s.l. infection rate of questing ticks. In contrast, sand lizards might act as reservoir hosts for R. helvetica. Remarkably, the public health risk from tick-borne diseases is approximately five times lower in heather than in woodland, due to the low tick densities in heather.

  7. Prey-handling and the evolutionary ecology of sand-swimming lizards (Lerista : Scincidae).

    Science.gov (United States)

    Pough, F Harvey; Preest, Marion R; Fusari, Margaret H

    1997-10-01

    Fossorial lizards differ in morphology from their surface-dwelling relatives. The Australian sphenomorphine skink genus Ctenotus consists of surface-dwelling species, and is closely related to the genus Lerista, which includes both surface-dwelling and fossorial species. Sand-swimming represents the derived condition and has evolved independently in several lineages of Lerista. The heads of lizards in the two genera differ in shape (blunt snout for Ctenotus versus wedge-shaped for Lerista) and in length relative to the body (approximately 20% of snout-vent length for Ctenotus versus 12% for sand-swimming Lerista). Do these specializations affect the sizes or types of prey that can be consumed by Lerista? We compared prey-handling by Ctenotus and Lerista to correlate morphological differences with differences in prey-handling ability, and to distinguish the effects of snout shape and head length. Feeding trials included three categories of insect prey that the lizards normally eat: soft-bodied larvae (Lepidoptera), hard-bodied larvae (Coleoptera), and roaches (Blatoidea). In comparisons based on the mass of a prey item relative to the mass of a lizard, Lerista had longer handling times for all prey categories and were limited to smaller prey than were Ctenotus. However, when comparisons were based on the length of prey relative to the length of a lizard's head, Lerista ate some elongate prey as fast or faster than did Ctenotus, and both genera successfully swallowed prey more than twice the length of their own head. Thus, the differences in prey-handling performance of Ctenotus and Lerista probably result from the fact that Lerista have a relatively shorter head than Ctenotus. All Lerista species, surface-dwelling and fossorial, have short heads compared to primitive sphenomorphine lizards. Fossorial species of Lerista have elongate trunks, and consequently their heads are shorter in proportion to trunk length than those of surface-dwelling Lerista. However, most

  8. Impact and intrusion of the foot of a lizard running rapidly on sand

    Science.gov (United States)

    Li, Chen; Hsieh, Tonia; Umbanhowar, Paul; Goldman, Daniel

    2012-11-01

    The desert-dwelling zebra-tailed lizard (Callisaurus draconoides, 10 cm, 10 g) runs rapidly (~10 BL/s) on granular media (GM) like sand and gravel. On loosely packed GM, its large hind feet penetrate into the substrate during each step. Based on above-ground observation, a previous study (Li et al., JEB 2012) hypothesized that the hind foot rotated in the vertical plane subsurface to generate lift. To explain the observed center-of-mass dynamics, the model assumed that ground reaction force was dominated by speed-independent frictional drag. Here we use x-ray high speed video to obtain subsurface foot kinematics of the lizard running on GM, which confirms the hypothesized subsurface foot rotation following rapid foot impact at touchdown. However, using impact force measurements, a resistive force model, and the observed foot kinematics, we find that impact force during initial foot touchdown and speed-independent frictional drag during rotation only account for part of the required lift to support locomotion. This suggests that the rapid foot rotation further allows the lizard to utilize inertial forces from the local acceleration of the substrate (particles), similar to small robots running on GM (Qian et al., RSS 2012) and the basilisk (Jesus) lizard running on water.

  9. [Influence of temperature on the rate of spermatogenesis, duration of spermatogenic activity and development of secondary sex characteristics in the wall-lizard, Lacerta muralis L. (Reptilia, Lacertidae)].

    Science.gov (United States)

    Joly, J; Saint Girons, H

    1975-01-01

    A series of experiments was carried out primarily between the 22nd of March and the 27th of June, on 60 Lacerta muralis maintained either under semi-natural conditions in large enclosures or in constant-temperature cabinets maintained at 17.5 degrees C, 20 degrees C, 22.5 degrees C and 27.5 degrees C with a natural photoperiod. Following an injection of tritiated thymidine, the animals were sacrificed at regular intervals and the rate of spermatogenesis was deduced from the progression of the radioactive front in the seminiferous epithelium. The following results were obtained: 1. The rate of spermatogenesis is temperature dependent and increases by a factor of approximately 1.2 per degree centigrade between 17.5 and 27.5 degrees C. The rate is seven times greater at 27.5 degrees C than at 17.5 degrees C. 2. Under semi-natural conditions the interval leptotene-spermatozooid lasts 70 days, slightly less than that found at a constant temperature of 22.5 degrees C. 3. Under semi-natural conditions the rate of spermatogenesis was similar to that in August-September, April-May and May-June which indicates that the lizards were able to maintain their body temperature at an equivalent level by behavioural temperature regulation during the greater part of their activity period. 4. Under semi-natural conditions, or at temperatures in excess of 22 degrees C, spermiogenesis lasts 1.8 times as long as meiosis. 5. At constant temperatures lower than 21 degrees C the development of the cellular lineage is aressted at the young spermatid stage. 6. Constant temperatures between 17.5 and 22.5 degrees C had no effect on the time of involution of the testis at the start of summer. 7. At low constant temperatures, secondary sexual characteristics regress before the usual time: after 4 weeks at 20 degrees C and after 8 weeks at 17.5 degrees C. An expected regression after 8 weeks produced after exposure to a temperature of 22.5 degrees C is probably due to factors other than

  10. Adaptation to life in aeolian sand: how the sandfish lizard, Scincus scincus, prevents sand particles from entering its lungs.

    Science.gov (United States)

    Stadler, Anna T; Vihar, Boštjan; Günther, Mathias; Huemer, Michaela; Riedl, Martin; Shamiyeh, Stephanie; Mayrhofer, Bernhard; Böhme, Wolfgang; Baumgartner, Werner

    2016-11-15

    The sandfish lizard, Scincus scincus (Squamata: Scincidae), spends nearly its whole life in aeolian sand and only comes to the surface for foraging, defecating and mating. It is not yet understood how the animal can respire without sand particles entering its respiratory organs when buried under thick layers of sand. In this work, we integrated biological studies, computational calculations and physical experiments to understand this phenomenon. We present a 3D model of the upper respiratory system based on a detailed histological analysis. A 3D-printed version of this model was used in combination with characteristic ventilation patterns for computational calculations and fluid mechanics experiments. By calculating the velocity field, we identified a sharp decrease in velocity in the anterior part of the nasal cavity where mucus and cilia are present. The experiments with the 3D-printed model validate the calculations: particles, if present, were found only in the same area as suggested by the calculations. We postulate that the sandfish has an aerodynamic filtering system; more specifically, that the characteristic morphology of the respiratory channel coupled with specific ventilation patterns prevent particles from entering the lungs.

  11. Adaptation to life in aeolian sand: how the sandfish lizard, Scincus scincus, prevents sand particles from entering its lungs

    Science.gov (United States)

    Vihar, Boštjan; Günther, Mathias; Huemer, Michaela; Riedl, Martin; Shamiyeh, Stephanie; Mayrhofer, Bernhard; Böhme, Wolfgang; Baumgartner, Werner

    2016-01-01

    ABSTRACT The sandfish lizard, Scincus scincus (Squamata: Scincidae), spends nearly its whole life in aeolian sand and only comes to the surface for foraging, defecating and mating. It is not yet understood how the animal can respire without sand particles entering its respiratory organs when buried under thick layers of sand. In this work, we integrated biological studies, computational calculations and physical experiments to understand this phenomenon. We present a 3D model of the upper respiratory system based on a detailed histological analysis. A 3D-printed version of this model was used in combination with characteristic ventilation patterns for computational calculations and fluid mechanics experiments. By calculating the velocity field, we identified a sharp decrease in velocity in the anterior part of the nasal cavity where mucus and cilia are present. The experiments with the 3D-printed model validate the calculations: particles, if present, were found only in the same area as suggested by the calculations. We postulate that the sandfish has an aerodynamic filtering system; more specifically, that the characteristic morphology of the respiratory channel coupled with specific ventilation patterns prevent particles from entering the lungs. PMID:27852763

  12. Effects of tail loss on locomotor ability and selected body temperature of common lizard Lacerta vivipara.%断尾对胎生蜥蜴运动能力和选择体温的影响

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 刘琳琳; 刘志涛; 夏玉国; 计翔; 赵文阁

    2011-01-01

    尾自切是蜥蜴为了降低被捕食危险而采取的一种反捕食适应策略,但断尾可导致体重减轻、热量收支平衡改变,并影响蜥蜴的运动能力和体温调节.为检验断尾对蜥蜴运动能力和选择体温的影响,于2006年5月选取黑龙江省小兴安岭地区的一个胎生蜥蜴种群进行实验.结果表明:在30 ℃和24℃两个实验温度下,断尾后胎生蜥蜴的运动能力均明显下降,表现在停顿次数增多、最大可持续距离和最大疾跑速度减少等方面;断尾、温度和性别对胎生蜥蝎运动能力的影响在一定程度上是相互独立的,断尾是影响胎生蜥蜴运动能力的主要因素;断尾对胎生蜥蝎的选择体温没有显著影响.%Tail autotomy is an effective anti-predator strategy adopted by many lizards, but can induce the decrease of their body mass and the changes in their energy balance, giving effects on their locomotor ability and body temperature adjustment. In this paper, a common lizard {Lacerta vivipara) population was collected from Xiaoxing' an Mountains in Heilongjiang Province of Northeast China in May 2006 to examine the effects of tail loss on the L. Vivipara locomotor ability and selected body temperature. At experimental temperature 30 °C and 24 °C, the tail loss of L. Vivipara resulted in an obvious reduction in its locomotor performances. More specifically, the frequency of stopping locomotion increased whereas the maximum distance of continuous locomotion and the sprint speed decreased. To some extent, the effects of tail loss, experimental temperature , and sex on the locomotor ability of L. Vivipara were independently. Tail loss was the main factor affecting the locomotor ability, but had little effects on the selected body temperature.

  13. Effects of oil pollution at Kuwait's Greater Al-Burgan oil field on the timing of morning emergence, basking and foraging behaviors by the sand lizard Acanthodactylus scutellatus.

    Science.gov (United States)

    Al-Hashem, M Abdulla; Brain, P F; Omar, S Ahmad

    2008-02-15

    An attempt was made to study the effects of oil pollution in a desert location (the Greater Al-Burgan oil fields, an area damaged in the second Gulf War) in Kuwait on the behaviour of the Sand lizard A. scutellatus. Polluted sites with apparently different degrees of contamination (namely tar mat, soot and clear sites) were compared with control areas outside this region. Between 2002 and 2003, ten lizards (5 of each sex) on each polluted and each control site were observed in the field at a time of the year when they were highly active. Air, substrate and burrow temperatures were recorded and lizards were monitored for their morning emergence times, as well as their basking and foraging activities. The present study confirmed that the morning emergence times and the basking behavior varied in sand lizards among the different pollution site categories. Physical changes in the tar mat sites caused the substrate temperatures in these locations to rise more quickly in the morning in response to solar gain than was the case in the other sites. This gives lizards in these locations the opportunity to emerge earlier and to start eating more quickly, giving them an energetic advantage (perhaps, in turn, influencing their rates of growth and fecundity). The clear sites had the next earliest emergence and were the next hottest but it is difficult to account for this in terms of the physical characteristics of this site. The basking times were clearly shorter on the dark soot and tar mat sites that appeared to have higher solar gain than control or clear sites. There did not appear to be any obvious differences in foraging activity of lizards in the different locations. It appears that some aspects of simple behaviour in these lizards provides a reliable, noninvasive indices for assessing oil pollution in desert locations. The precise impact of these changes in these reptiles on their long-term viability needs to be evaluated.

  14. Long-term sand supply to Coachella Valley Fringe-toed Lizard Habitat in the Northern Coachella Valley, California

    Science.gov (United States)

    Griffiths, Peter G.; Webb, Robert H.; Lancaster, Nicholas; Kaehler, Charles A.; Lundstrom, Scott C.

    2002-01-01

    The Coachella Valley fringe-toed lizard (Uma inornata) is a federally listed threatened species that inhabits active sand dunes in the vicinity of Palm Springs, California. The Whitewater Floodplain and Willow Hole Reserves provide some of the primary remaining habitat for this species. The sediment-delivery system that creates these active sand dunes consists of fluvial depositional areas fed episodically by ephemeral streams. Finer fluvial sediments (typically sand size and finer) are mobilized in a largely unidirectional wind field associated with strong westerly winds through San Gorgonio Pass. The fluvial depositional areas are primarily associated with floodplains of the Whitewater?San Gorgonio Rivers and Mission Creek?Morongo Wash; other small drainages also contribute fluvial sediment to the eolian system. The eolian dunes are transitory as a result of unidirectional sand movement from the depositional areas, which are recharged with fine-grained sediment only during episodic floods that typically occur during El Ni?o years. Eolian sand moves primarily from west to east through the study area; the period of maximum eolian activity is April through June. Wind speed varies diurnally, with maximum velocities typically occurring during the afternoon. Development of alluvial fans, alteration of stream channels by channelization, in-stream gravel mining, and construction of infiltration galleries were thought to reduce the amount of fluvial sediment reaching the depositional areas upwind of Uma habitat. Also, the presence of roadways, railroads, and housing developments was thought to disrupt or redirect eolian sand movement. Most of the sediment yield to the fluvial system is generated in higher elevation areas with little or no development, and sediment yield is affected primarily by climatic fluctuations and rural land use, particularly livestock grazing and wildfire. Channelization benefits sediment delivery to the depositional plains upwind of the reserves

  15. Diet of the lizard Liolaemus occipitalis in the coastal sand dunes of southern Brazil (Squamata-Liolaemidae).

    Science.gov (United States)

    Verrastro, L; Ely, I

    2015-05-01

    Knowledge of a species' diet provides important information on adaptation and the relationship between the organism and its environment. The genus Liolaemus occurs in the southern region of South America and is an excellent model to investigate the adaptive processes of vertebrate ecology in ecosystems of this region of the world. Liolaemus occipitalis is an endangered species that inhabits the coastal sand dunes of southern Brazil. This species is the most abundant vertebrate in this environment, and it presents unique adaptation characteristics to the restinga environment. The present study analyzed this lizard's diet to verify similarities or differences between this species and other species of the same genus. Specimens were collected monthly from January 1996 to December 1997. The number of items, frequency of occurrence and volume of each prey taxon were determined. Arthropods were identified to the order level, and plant material was identified as flower, fruit, seed and leaves. Variations in the diet of males and females, adults and juveniles and seasons were also analyzed. The data indicate that Liolaemus occipitalis is a generalist, "sit-and-wait" or ambush predator as well as omnivorous, feeding on both arthropods and plant material. Significant ontogenetic differences were verified. Juveniles are more carnivorous, and the intake of plant material increases with size and age. Seasonal differences in diet composition were also observed. In the spring, arthropod and plant materials were more diversified and, therefore, consumed more often.

  16. Phylogeography and demographic history of Lacerta lepida in the Iberian Peninsula

    DEFF Research Database (Denmark)

    Miraldo, Andreia; Hewitt, Godfrey M; Paulo, Octavio S;

    2011-01-01

    either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida...

  17. A potential recovery of a population of the sand lizard Liolaemus lutzae Mertens, 1938 in an area within its range: a lizard endemic and threatened with extinction

    Directory of Open Access Journals (Sweden)

    CFD. Rocha

    Full Text Available The endemic and threatened lizard Liolaemus lutzae has a relatively small geographic range restricted to only 200 km of along the coast of Rio de Janeiro State, Brazil, which are habitats under intensive anthropic disturbance. At the Barra da Tijuca beach, in Rio de Janeiro city an estimate of the population abundance made in 1991, compared to a previous estimate made in 1984, showed a considerable decrease (about 65%. Most of the decrease was attributed to anthropic disturbances that locally affected the beach vegetation, the species habitat. In this study we present estimates made in 2002 and in 2006 at the same area and compare them with the estimates of 1984 and 1991, using the same methodology in order to make comparable the data from different samplings years and to evaluate the present status of the local population. The estimated indexes of L. lutzae abundance in 2002 and in 2006 were higher than that of 1991. There was a significant increase in the mean number of recorded lizards in 2002 compared to 1991, but the mean number of lizards sighted in 2006 remained stable when compared with that of 2002. Our data based on the index of abundance recorded suggested that the number of L. lutzae at Barra da Tijuca beach recorded increased, which can be indicative of a potential recovery of the local population.

  18. Sequence variation in the melanocortin-1 receptor (MC1R pigmentation gene and its role in the cryptic coloration of two South American sand lizards

    Directory of Open Access Journals (Sweden)

    Josmael Corso

    2012-01-01

    Full Text Available In reptiles, dorsal body darkness often varies with substrate color or temperature environment, and is generally presumed to be an adaptation for crypsis or thermoregulation. However, the genetic basis of pigmentation is poorly known in this group. In this study we analyzed the coding region of the melanocortin-1-receptor (MC1R gene, and therefore its role underlying the dorsal color variation in two sympatric species of sand lizards (Liolaemus that inhabit the southeastern coast of South America: L. occipitalis and L. arambarensis. The first is light-colored and occupies aeolic pale sand dunes, while the second is brownish and lives in a darker sandy habitat. We sequenced 630 base pairs of MC1R in both species. In total, 12 nucleotide polymorphisms were observed, and four amino acid replacement sites, but none of them could be associated with a color pattern. Comparative analysis indicated that these taxa are monomorphic for amino acid sites that were previously identified as functionally important in other reptiles. Thus, our results indicate that MC1R is not involved in the pigmentation pattern observed in Liolaemus lizards. Therefore, structural differences in other genes, such as ASIP, or variation in regulatory regions of MC1R may be responsible for this variation. Alternatively, the phenotypic differences observed might be a consequence of non-genetic factors, such as thermoregulatory mechanisms.

  19. A contibution to the knowledge of the trophic spectrum of three lacertid lizards from Bulgaria

    Directory of Open Access Journals (Sweden)

    Ivelin Mollov

    2013-01-01

    Full Text Available A study on the trophic spectrum of three species of lacertid lizards (Lacerta agilis, Lacerta trilineata and Podarcis muralis was carried out, based on 20 specimens collected in the period 1967-1973 in various localities in Bulgaria. The analyzed data showed that the insects (Insecta are the most numerous and the most frequently met among the alimentary components of the total amount of food of the studied stomachs (except for Lacerta agilis, where spiders are slightly predominating. The non-insect components consisted spiders and isopods. The largest niche breadth was recorded in Lacerta trilineata (8.25, followed by Podarcis muralis (5.20 and Lacerta agilis (3.44. The niche overlap between the three species (pair-wise comparison showed medium values and in our opinion there should not be any serious competition for food resources at the places withsympatric distribution.

  20. Mating Behavior of the Common Lizard Lacerta vivipara and the Relationship with Environment Factors%模拟生境中胎生蜥蜴的交配行为及其与环境因子的关系

    Institute of Scientific and Technical Information of China (English)

    李殿伟; 刘鹏; 赵文阁

    2011-01-01

    摘要:2007年和2008年的5月,采用瞬时扫描取样法和全事件观察法,对模拟生境中胎生蜥蝎(Lacerta vivipara)的交配行为进行了详细的研究。结果表明,胎生蜥蜴交配行为的基本模式为:①追逐;②咬腹;③环抱;④交媾;⑤分离。其中各交配行为持续时间占总交配时间的百分比分别为:追逐占2. 35%,咬腹占0.51%,环抱占8.44%,交媾占88.70%。交配活动主要发生在8:00时以后,其中9:00 ~ 13:00时比较集中,此间光照强度平均为(1 009.90±77.06) ×102 lx[(307.00×102)~(1 999.00×102)1x],气温平均为(31.53 ±0.36)℃(25. 10 ~39. 20℃),地表温度平均为(41.03±0.60)℃(28.30 ~56.30℃),湿度平均为27.54%±0.58%(20. 00% ~ 43. 50%)。经检验,交配活动受地表温度(r=0. 829,P<0.01)、光照强度(r =0.664,P<0. 05)与气温(r=0.606,P<0.05)的影响显著。%The mating behaviors of Lacerta viviparavteie studied in the May of 2007 and 2008 by the methods of instantaneous and scan sampling and of all-occurrence recording. The results show that the basic patterns of mating behavior of L vivipara are chasing; biting abdomen; encircling; sexual intercourse and separating. Chasing accounts for 2.35% of total time; biting abdomen for 0.51% ; encircling for 8.44% and sexual intercourse for 88. 70% . The mating activities begin at 8 a. M. And focus from 9 a. M. To 1 p. M. During the period, the average illumination intensity is ( 1 009. 90 ±77. 06) x 102 lx [ (307. 00 x 102 ) - (1 999. 00 x 102)lx]; the average air temperature is (31.53 ±0.36)% (25.10 - 39.2CC ) ; the average ground temperature is (41.03 ±0.60)1] (28.30 -56.30%); and the average humidity is 27.54% ±0.58% (20. 00% - 43. 50% ). Environment factors, such as ground temperature, illumination and air temperature, mainly affected the mating behaviors of L. Vivipara.

  1. Structure of capsule around acanthocephalan Corynosoma strumosum from uncommon paratenic hosts-lizards of two species.

    Science.gov (United States)

    Skorobrechova, Ekaterina M; Nikishin, Vladimir P; Lisitsyna, Olga I

    2012-01-01

    Micromorphology and ultrastructure of capsule forming around acanthocephalan Corynosoma strumosum in uncommon paratenic hosts-lizards Lacerta agilis and Lacerta viridis-have been studied. Experimental infestation of the lizards by acanthocephalans obtained from naturally infested sea fishes showed that only small amount of parasites occurred in the intestine of the host was able to migrate into body cavity and to be encapsulated. Micromorphology of capsules of different ages from different species of lizards and micromorphology and ultrastructure of capsules at the age of 1.5 and 10 days appeared to be similar. In the capsule's structure cells of inflammatory rank were prevailing: mononuclear and multinuclear macrophages, eosinophils, and basophils. Fibroblasts were not numerous and were located only in the outer part of a capsule; exocellular collagen fibers were absent. Inflammatory character of capsule confirms the idea that lizards are unsuitable paratenic hosts for corynosomes.

  2. Diet of the lizard Liolaemus occipitalis in the coastal sand dunes of southern Brazil (Squamata-Liolaemidae

    Directory of Open Access Journals (Sweden)

    L. Verrastro

    Full Text Available Knowledge of a species’ diet provides important information on adaptation and the relationship between the organism and its environment. The genus Liolaemus occurs in the southern region of South America and is an excellent model to investigate the adaptive processes of vertebrate ecology in ecosystems of this region of the world. Liolaemus occipitalis is an endangered species that inhabits the coastal sand dunes of southern Brazil. This species is the most abundant vertebrate in this environment, and it presents unique adaptation characteristics to the restinga environment. The present study analyzed this lizard’s diet to verify similarities or differences between this species and other species of the same genus. Specimens were collected monthly from January 1996 to December 1997. The number of items, frequency of occurrence and volume of each prey taxon were determined. Arthropods were identified to the order level, and plant material was identified as flower, fruit, seed and leaves. Variations in the diet of males and females, adults and juveniles and seasons were also analyzed. The data indicate that Liolaemus occipitalis is a generalist, “sit-and-wait” or ambush predator as well as omnivorous, feeding on both arthropods and plant material. Significant ontogenetic differences were verified. Juveniles are more carnivorous, and the intake of plant material increases with size and age. Seasonal differences in diet composition were also observed. In the spring, arthropod and plant materials were more diversified and, therefore, consumed more often.

  3. Radio outburst of BL Lacertae

    Science.gov (United States)

    Buemi, C. S.; Leto, P.; Trigilio, C.; Umana, G.; Giroletti, M.; Orienti, M.; Raiteri, C. M.; Villata, M.; Bach, U.

    2013-04-01

    We report on extremely high radio flux of BL Lacertae at 43 and 8 GHz. Observations at 43 GHz with the 32 m radio telescope in Noto (Italy) revealed a flux density of 10.5 +/- 0.2 Jy on 2013 April 10.65, while observations at 8 GHz with the 32 m radio telescope in Medicina (Italy) detected a flux density of 8.2 +/- 0.7 Jy on April 12.22. These extremely high radio fluxes show that the radio activity likely correlated to the strong optical, near-infrared, and gamma-ray activity of 2011-2012 (see ATels #4028, #4031, #4155, #4271, #4277, #4349, #4565, #4600), and X-ray activity of late 2012 (ATels #4557, #4627), is far to be exhausted.

  4. Distribution pattern and number of ticks on lizards.

    Science.gov (United States)

    Dudek, Krzysztof; Skórka, Piotr; Sajkowska, Zofia Anna; Ekner-Grzyb, Anna; Dudek, Monika; Tryjanowski, Piotr

    2016-02-01

    The success of ectoparasites depends primarily on the site of attachment and body condition of their hosts. Ticks usually tend to aggregate on vertebrate hosts in specific areas, but the distribution pattern may depend on host body size and condition, sex, life stage or skin morphology. Here, we studied the distribution of ticks on lizards and tested the following hypothesis: occurrence or high abundance of ticks is confined with body parts with smaller scales and larger interscalar length because such sites should provide ticks with superior attachment conditions. This study was performed in field conditions in central Poland in 2008-2011. In total, 500 lizards (Lacerta agilis) were caught and 839 ticks (Ixodes ricinus, larvae and nymphs) were collected from them. Using generalised linear mixed models, we found that the ticks were most abundant on forelimbs and their axillae, with 90% of ticks attached there. This part of the lizard body and the region behind the hindlimb were covered by the smallest scales with relatively wide gaps between them. This does not fully support our hypothesis that ticks prefer locations with easy access to skin between scales, because it does not explain why so few ticks were in the hindlimb area. We found that the abundance of ticks was positively correlated with lizard body size index (snout-vent length). Tick abundance was also higher in male and mature lizards than in female and young individuals. Autotomy had no effect on tick abundance. We found no correlation between tick size and lizard morphology, sex, autotomy and body size index. The probability of occurrence of dead ticks was positively linked with the total number of ticks on the lizard but there was no relationship between dead tick presence and lizard size, sex or age. Thus lizard body size and sex are the major factors affecting the abundance of ticks, and these parasites are distributed nearly exclusively on the host's forelimbs and their axillae.

  5. Biographical material about S. S. Liberman and N. V.Pokrovskaya – the authors of the article on thermal biology of the sand lizard, 1943, and about the people involved in that work

    Directory of Open Access Journals (Sweden)

    Cherlin Vladimir A.

    2017-03-01

    Full Text Available The article gives some biographical data about the authors of wonderful, landmark article on the thermal biology of the sand lizard. It was published in 1943, and in our opinion it was the first serious article on thermal biology of reptiles, which should consider the beginning of the researches in this scientific field. In 1940-s Serafima S.Lieberman and Nina V.Pokrovskaya were the students of the biological faculty of Moscow state University and worked in the Department of vertebrate zoology. Together with the whole country, they bravely endured the difficulties of the great Patriotic war and, as best they could, contributed to the victory. Their scientific supervisors were the remarkable biologists who worked at the same Department: A. M. Sergeev, Prof. A. N. Formozov and Prof. B. S. Matveev, and that perhaps helped their work to become so important. Later, however, they did not link their activities with Herpetology and worked in other fields of biology. Sima Lieberman and Nina Pokrovskaya were warm friends all their lives. Their children and grandchildren maintain good relations up today.

  6. What are carotenoids signaling? Immunostimulatory effects of dietary vitamin E, but not of carotenoids, in Iberian green lizards

    Science.gov (United States)

    Kopena, Renata; López, Pilar; Martín, José

    2014-12-01

    In spite that carotenoid-based sexual ornaments are one of the most popular research topics in sexual selection of animals, the antioxidant and immunostimulatory role of carotenoids, presumably signaled by these colorful ornaments, is still controversial. It has been suggested that the function of carotenoids might not be as an antioxidant per se, but that colorful carotenoids may indirectly reflect the levels of nonpigmentary antioxidants, such as melatonin or vitamin E. We experimentally fed male Iberian green lizards ( Lacerta schreiberi) additional carotenoids or vitamin E alone, or a combination of carotenoids and vitamin E dissolved in soybean oil, whereas a control group only received soybean oil. We examined the effects of the dietary supplementations on phytohaemagglutinin (PHA)-induced skin-swelling immune response and body condition. Lizards that were supplemented with vitamin E alone or a combination of vitamin E and carotenoids had greater immune responses than control lizards, but animals supplemented with carotenoids alone had lower immune responses than lizards supplemented with vitamin E and did not differ from control lizards. These results support the hypothesis that carotenoids in green lizards are not effective as immunostimulants, but that they may be visually signaling the immunostimulatory effects of non-pigmentary vitamin E. In contrast, lizards supplemented with carotenoids alone have higher body condition gains than lizards in the other experimental groups, suggesting that carotenoids may be still important to improve condition.

  7. Choosing between a rock and a hard place: Camouflage in the round-tailed horned lizard Phrynosoma modestum

    Institute of Scientific and Technical Information of China (English)

    William E.COOPER; Wade C.SHERBROOKE

    2012-01-01

    The round-tailed horned lizard Phrynosoma modestum is cryptically colored and resembles a small stone when it draws legs close to its body and elevates its back.We investigated effectiveness of camouflage in P.modestum and its dependence on stones by placing a lizard in one of two microhabitats (uniform sand or sand with surface rocks approximately the same size as lizards).An observer who knew which microhabitat contained the lizard was asked to locate the lizard visually.Latency to detection was longer and probability of no detection within 60 s was higher for lizards on rock background than on bare sand.In arenas where lizards could choose to occupy rock or bare sand,much higher proportions selected rocky backgrounds throughout the day;at night all lizards slept among stones.A unique posture gives P.modestum a rounded appearance similar to many natural stones.Lizards occasionally adopted the posture,but none did so in response to a nearby experimenter.Stimuli that elicit the posture are unknown.That P.modestum is better camouflaged among rocks than on bare sand and prefers to occupy rocky areas suggests that special resemblance to rocks (masquerade) enhances camouflage attributable to coloration and immobility.

  8. Time Series Photometry of KZ Lacertae

    Science.gov (United States)

    Joner, Michael D.

    2016-01-01

    We present BVRI time series photometry of the high amplitude delta Scuti star KZ Lacertae secured using the 0.9-meter telescope located at the Brigham Young University West Mountain Observatory. In addition to the multicolor light curves that are presented, the V data from the last six years of observations are used to plot an O-C diagram in order to determine the ephemeris and evaluate evidence for period change. We wish to thank the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for their continued support of the research activities at the West Mountain Observatory.

  9. Observations of BL Lacertae with MAGIC telescope

    Directory of Open Access Journals (Sweden)

    E. J. Lindfors

    2008-01-01

    Full Text Available BL Lacertae fue observado con el telescopio MAGIC de agosto a diciembre de 2005 (22.2 horas y de julio a septiembre de 2006 (26.0 horas. En 2005 se detectó, con un nivel de significación 5.1 σ, una fuerte emisión de rayos γ de muy alta energía (VHE. BL Lacertae es el primer objeto BL Lac con un pico de emisión a bajas frecuencias, en el cual se detecta este tipo de emisión. En los datos de 2006, no hay detección en la región de los rayos γ, lo que se atribuye a un menor nivel de flujo en este periodo. En este trabajo mostramos que también se observa una caida en el flujo óptico y milimétrico, lo cual sugiere una conexión entre estas tres bandas de emisión.

  10. Optical and Radio Variability of BL Lacertae

    CERN Document Server

    Gaur, Haritma; Bachev, R; Strigachev, A; Semkov, E; Wiita, Paul J; Volvach, A E; Gu, Minfeng; Agarwal, A; Agudo, I; Aller, M F; Aller, H D; Kurtanidze, O M; Kurtanidze, S O; Lahteenmaki, A; Peneva, S; Nikolashvili, M G; Sigua, L A; Tornikoski, M; Volvach, L N

    2015-01-01

    We observed the prototype blazar, BL Lacertae, extensively in optical and radio bands during an active phase in the period 2010--2013 when the source showed several prominent outbursts. We searched for possible correlations and time lags between the optical and radio band flux variations using multifrequency data to learn about the mechanisms producing variability. During an active phase of BL Lacertae, we searched for possible correlations and time lags between multifrequency light curves of several optical and radio bands. We tried to estimate any possible variability timescales and inter-band lags in these bands. We performed optical observations in B, V, R and I bands from seven telescopes in Bulgaria, Georgia, Greece and India and obtained radio data at 36.8, 22.2, 14.5, 8 and 4.8 GHz frequencies from three telescopes in Ukraine, Finland and USA. Significant cross-correlations between optical and radio bands are found in our observations with a delay of cm-fluxes with respect to optical ones of ~250 days...

  11. Patterns of cranial ontogeny in lacertid lizards: morphological and allometric disparity.

    Science.gov (United States)

    Urošević, A; Ljubisavljević, K; Ivanović, A

    2013-02-01

    We explored the ontogenetic dynamics of the morphological and allometric disparity in the cranium shapes of twelve lacertid lizard species. The analysed species (Darevskia praticola, Dinarolacerta mosorensis, Iberolacerta horvathi, Lacerta agilis, L. trilineata, L. viridis, Podarcis erhardii, P. melisellensis, P. muralis, P. sicula, P. taurica and Zootoca vivipara) can be classified into different ecomorphs: terrestrial lizards that inhabit vegetated habitats (habitats with lush or sparse vegetation), saxicolous and shrub-climbing lizards. We observed that there was an overall increase in the morphological disparity (MD) during the ontogeny of the lacertid lizards. The ventral cranium, which is involved in the mechanics of jaw movement and feeding, showed higher levels of MD, an ontogenetic shift in the morphospace planes and more variable allometric patterns than more conserved dorsal crania. With respect to ecology, the allometric trajectories of the shrub-climbing species tended to cluster together, whereas the allometric trajectories of the saxicolous species were highly dispersed. Our results indicate that the ontogenetic patterns of morphological and allometric disparity in the lacertid lizards are modified by ecology and functional constraints and that the identical mechanisms that lead to intraspecific morphological variation also produce morphological divergence at higher taxonomic levels.

  12. Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

    Science.gov (United States)

    Fitze, Patrick S.; Cote, Julien; San-Jose, Luis Martin; Meylan, Sandrine; Isaksson, Caroline; Andersson, Staffan; Rossi, Jean-Marc; Clobert, Jean

    2009-01-01

    Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake) or due to the activation of the physiological stress response (PSR, e.g. due to increased blood corticosterone concentrations). Here, we tested whether blood corticosterone concentration affected carotenoid-based colouration, and whether a trade-off between colouration and PSR existed. Using the common lizard (Lacerta vivipara), we correlatively and experimentally showed that elevated blood corticosterone levels are associated with increased redness of the lizard's belly. In this study, the effects of corticosterone did not depend on carotenoid ingestion, indicating the absence of a trade-off between colouration and PSR for carotenoids. While carotenoid ingestion increased blood carotenoid concentration, colouration was not modified. This suggests that carotenoid-based colouration of common lizards is not severely limited by dietary carotenoid intake. Together with earlier studies, these findings suggest that the common lizard's carotenoid-based colouration may be a composite trait, consisting of fixed (e.g. genetic) and environmentally elements, the latter reflecting the lizard's PSR. PMID:19352507

  13. Carotenoid-based colours reflect the stress response in the common lizard.

    Directory of Open Access Journals (Sweden)

    Patrick S Fitze

    Full Text Available Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake or due to the activation of the physiological stress response (PSR, e.g. due to increased blood corticosterone concentrations. Here, we tested whether blood corticosterone concentration affected carotenoid-based colouration, and whether a trade-off between colouration and PSR existed. Using the common lizard (Lacerta vivipara, we correlatively and experimentally showed that elevated blood corticosterone levels are associated with increased redness of the lizard's belly. In this study, the effects of corticosterone did not depend on carotenoid ingestion, indicating the absence of a trade-off between colouration and PSR for carotenoids. While carotenoid ingestion increased blood carotenoid concentration, colouration was not modified. This suggests that carotenoid-based colouration of common lizards is not severely limited by dietary carotenoid intake. Together with earlier studies, these findings suggest that the common lizard's carotenoid-based colouration may be a composite trait, consisting of fixed (e.g. genetic and environmentally elements, the latter reflecting the lizard's PSR.

  14. Carotenoid-based colours reflect the stress response in the common lizard.

    Science.gov (United States)

    Fitze, Patrick S; Cote, Julien; San-Jose, Luis Martin; Meylan, Sandrine; Isaksson, Caroline; Andersson, Staffan; Rossi, Jean-Marc; Clobert, Jean

    2009-01-01

    Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake) or due to the activation of the physiological stress response (PSR, e.g. due to increased blood corticosterone concentrations). Here, we tested whether blood corticosterone concentration affected carotenoid-based colouration, and whether a trade-off between colouration and PSR existed. Using the common lizard (Lacerta vivipara), we correlatively and experimentally showed that elevated blood corticosterone levels are associated with increased redness of the lizard's belly. In this study, the effects of corticosterone did not depend on carotenoid ingestion, indicating the absence of a trade-off between colouration and PSR for carotenoids. While carotenoid ingestion increased blood carotenoid concentration, colouration was not modified. This suggests that carotenoid-based colouration of common lizards is not severely limited by dietary carotenoid intake. Together with earlier studies, these findings suggest that the common lizard's carotenoid-based colouration may be a composite trait, consisting of fixed (e.g. genetic) and environmentally elements, the latter reflecting the lizard's PSR.

  15. Intraday optical variability of BL Lacertae

    Science.gov (United States)

    Meng, Nankun; Wu, Jianghua; Webb, James R.; Zhang, Xiaoyuan; Dai, Yan

    2017-08-01

    We monitored BL Lacertae simultaneously in the optical B, V, R and I bands for 13 nights during the period 2012-2016. The variations were well correlated in all bands and the source showed significant intraday variability (IDV). We also studied its optical flux and colour behaviour, and searched for inter-band time lags. A strong bluer-when-brighter chromatism was found on the intra-night time-scale. The spectral changes are not sensitive to the host galaxy contribution. Cross-correlation analysis revealed possible time delay of about 10 min between variations in the V and R bands. We interpreted the observed flares in terms of the model consisting of individual synchrotron pulses.

  16. The Cosmological Evolution of BL Lacertae Objects

    CERN Document Server

    Giommi, P; Perri, M; Padovani, P

    2000-01-01

    We review the main results from several radio, X-ray and multi-frequency surveys on the topic of cosmological evolution of BL Lacertae objects. Updated findings on BL Lac evolution following the recent identification of many sources in the ``Sedentary Multi-Frequency survey'' are also discussed. By means of extensive Monte Carlo simulations we test some possible explanations for the peculiar cosmological evolution of BL Lacs. We find that a dependence of the relativistic Doppler factor on radio luminosity (as expected within the beaming scenario) may induce low values of V/V_max and that both edge effects at the low luminosity end of the BL Lacs radio luminosity function, and incompleteness at faint optical magnitudes may be the cause of the low V/V_max found for extreme HBL sources in X-ray selected samples.

  17. Communication Signals in Lizards.

    Science.gov (United States)

    Carpenter, Charles C.

    1983-01-01

    Discusses mechanisms and functional intent of visual communication signals in iguanid/agamid lizards. Demonstrated that lizards communicate with each other by using pushups and head nods and that each species does this in its own way, conveying different types of information. (JN)

  18. Wine industry market strategies. Case study: Lacerta Winery

    Directory of Open Access Journals (Sweden)

    NEACSU Nicoleta Andreea

    2017-01-01

    Full Text Available Wine market in Romania is in constant development. More and more manufacturers appear on the market, and the competition is increasingly fierce. Although it has an area of the largest planted with vines, Romania is not distinguished among major exporters. Using EU funds made available, new manufacturers appear who developed the premium wine sector. Among the investments carried out in recent years in this sector is Lacerta Winery, an Austrian investment, which sold the first wine under the brand Lacerta in 2011.

  19. Ciclos de actividad diaria y estacional de un gremio de saurios en las dunas de arena de Viesca, Coahuila, México Daily and seasonal activity patterns of a lizard guild in the sand dunes of Viesca, Coahuila, Mexico

    Directory of Open Access Journals (Sweden)

    Cristina García-De la Peña

    2007-06-01

    Full Text Available En el 2002 se evaluaron los ciclos de actividad diaria y estacional de los saurios Uta stejnegeri, Uma exsul y Aspidoscelis marmorata en un hábitat de dunas al suroeste de Coahuila, México. Se recorrió un transecto de 500 m, cada hora (de 0700 a 1900 h durante 7 días, en primavera, verano y otoño. Se registró el número de individuos activos por especie, la temperatura del aire y del sustrato, y la humedad relativa. La amplitud de nicho temporal se calculó mediante el Índice estandarizado de Levins, y el traslape de nicho mediante el método de Pianka. En las 3 estaciones del año U. stejnegeri inició su actividad más temprano que U. exsul, y ésta, a su vez, se registró antes que A. marmorata. Las 3 especies presentaron un ciclo de actividad bimodal durante primavera y verano, y unimodal en otoño. Aspidoscelis marmorata presentó la menor amplitud de nicho temporal durante las 3 estaciones. La temperatura corporal de cada especie y la temperatura ambiental parecen determinar los patrones de actividad de este gremio de saurios en Viesca.In 2002, daily and seasonal activity patterns of the lizards Uta stejnegeri, Uma exsul, and Aspidoscelis marmorata were evaluated in a dune habitat in the southwestern portion of Coahuila, Mexico. Methods included surveying a 500 m transect once per hour between 0700 and 1900 for 7 days each season during the spring, summer and fall. The number of active lizards, air and substrate temperatures, and relative humidity were recorded. A standardized Levins Index and Pianka’s method were used to measure temporal niche breadth and overlap, respectively. In each of the 3 seasons, U. stejnegeri was active earlier than U. exsul, and U. exsul was active before A. marmorata. The 3 species showed a bimodal activity pattern during spring and summer, and unimodal in fall. Aspidoscelis marmorata showed the smallest niche breadth in the 3 seasons. For each species, preferred body temperature and environmental

  20. Auditory hair cell innervational patterns in lizards.

    Science.gov (United States)

    Miller, M R; Beck, J

    1988-05-22

    The pattern of afferent and efferent innervation of two to four unidirectional (UHC) and two to nine bidirectional (BHC) hair cells of five different types of lizard auditory papillae was determined by reconstruction of serial TEM sections. The species studies were Crotaphytus wislizeni (iguanid), Podarcis (Lacerta) sicula and P. muralis (lacertids), Ameiva ameiva (teiid), Coleonyx variegatus (gekkonid), and Mabuya multifasciata (scincid). The main object was to determine in which species and in which hair cell types the nerve fibers were innervating only one (exclusive innervation), or two or more hair cells (nonexclusive innervation); how many nerve fibers were supplying each hair cell; how many synapses were made by the innervating fibers; and the total number of synapses on each hair cell. In the species studies, efferent innervation was limited to the UHC, and except for the iguanid, C. wislizeni, it was nonexclusive, each fiber supplying two or more hair cells. Afferent innervation varied both with the species and the hair cell types. In Crotaphytus, both the UHC and the BHC were exclusively innervated. In Podarcis and Ameiva, the UHC were innervated exclusively by some fibers but nonexclusively by others (mixed pattern). In Coleonyx, the UHC were exclusively innervated but the BHC were nonexclusively innervated. In Mabuya, both the UHC and BHC were nonexclusively innervated. The number of afferent nerve fibers and the number of afferent synapses were always larger in the UHC than in the BHC. In Ameiva, Podarcis, and Mabuya, groups of bidirectionally oriented hair cells occur in regions of cytologically distinct UHC, and in Ameiva, unidirectionally oriented hair cells occur in cytologically distinct BHC regions.

  1. Stable isotope analysis of diet confirms niche separation of two sympatric species of Namib Desert lizard.

    Science.gov (United States)

    Murray, Ian W; Lease, Hilary M; Hetem, Robyn S; Mitchell, Duncan; Fuller, Andrea; Woodborne, Stephan

    2016-01-01

    We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards, the Husab sand lizard Pedioplanis husabensis and Bradfield's Namib day gecko living sympatrically in the Namib Desert. We measured the δ(13) C and δ(15) N ratios in lizard blood tissues with different turnover times (whole blood, red blood cells and plasma) to investigate lizard diet in different seasons. We also measured the δ(13) C and δ(15) N ratios in available arthropod prey and plant tissues on the site, to identify the avenues of nutrient movement between lizards and their prey. Through the use of stable isotope mixing models, we found that the two lizard species relied on a largely non-overlapping but seasonally variable array of arthropods: P. husabensis primarily fed on termites, beetles and wasps, while R. bradfieldi fed mainly on ants, wasps and hemipterans. Nutrients originating from C3 plants were proportionally higher for R. bradfieldi than for P. husabensis during autumn and late autumn/early winter, although not summer. Contrary to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C3 and C4 /crassulacean acid metabolism (CAM) plant landscapes, we found that our lizard species primarily acquired nutrients that originated from C4 /CAM plants. This work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.

  2. A Braitenberg Lizard:

    DEFF Research Database (Denmark)

    Shaikh, Danish; Hallam, John; Christensen-Dalsgaard, Jakob;

    2009-01-01

    The peripheral auditory system of a lizard is structured as a pressure difference receiver with strong broadband directional sensitivity. Previous work has demonstrated that this system can be implemented as a set of digital filters generated by considering the lumped-parameter model of the audit......The peripheral auditory system of a lizard is structured as a pressure difference receiver with strong broadband directional sensitivity. Previous work has demonstrated that this system can be implemented as a set of digital filters generated by considering the lumped-parameter model...

  3. Comparative analysis of fiber-type composition in the iliofibularis muscle of phrynosomatid lizards (Squamata).

    Science.gov (United States)

    Bonine, K E; Gleeson, T T; Garland, T

    2001-12-01

    The lizard family Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. This family exhibits great variation in ecology, behavior, and general body plan. Previous studies also show that this family exhibits great diversity in locomotor performance abilities; as measured on a high-speed treadmill, sand lizards are exceptionally fast sprinters, members of the Sceloporus group are intermediate, and horned lizards are slowest. These differences are paralleled by differences in relative hindlimb span. To determine if muscle fiber-type composition also varies among the three subclades, we examined the iliofibularis (IF), a hindlimb muscle used in lizard locomotion, in 11 species of phrynosomatid lizards. Using histochemical assays for myosin ATPase, an indicator of fast-twitch capacity, and succinic dehydrogenase, denoting oxidative capacity, we classified fiber types into three categories based on existing nomenclature: fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), and slow-twitch oxidative (SO). Sand lizards have a high proportion of FG fibers (64-70%) and a low proportion of FOG fibers (25-33%), horned lizards are the converse (FG fibers 25-31%, FOG fibers 56-66%), and members of the Sceloporus group are intermediate for both FG (41-48%) and FOG (42-45%) content. Hence, across all 11 species %FOG and %FG are strongly negatively correlated. Analysis with phylogenetically independent contrasts indicate that this negative relationship is entirely attributable to the divergence between sand and horned lizards. The %SO also varies among the three subclades. Results from conventional nested ANCOVA (with log body mass as a covariate) indicate that the log mean cross-sectional area of individual muscle fibers differs among species and is positively correlated with body mass across species, but does not differ significantly among subclades. The log cross-sectional area of the IF

  4. Assessing the reliability of thermography to infer internal body temperatures of lizards.

    Science.gov (United States)

    Barroso, Frederico M; Carretero, Miguel A; Silva, Francisco; Sannolo, Marco

    2016-12-01

    For many years lizard thermal ecology studies have relied on the use of contact thermometry to obtain internal body temperature (Tb) of the animals. However, with progressing technology, an interest grew in using new, less invasive methods, such as InfraRed (IR) pyrometry and thermography, to infer Tb of reptiles. Nonetheless few studies have tested the reliability of these new tools. The present study tested the use of IR cameras as a non-invasive tool to infer Tb of lizards, using three differently body-sized lacertid species (Podarcis virescens, Lacerta schreiberi and Timon lepidus). Given the occurrence of regional heterothermy, we pairwise compared thermography readings of six body parts (snout, eye, head, dorsal, hind limb, tail base) to cloacal temperature (measured by a thermometer-associated thermocouple probe) commonly employed to measure Tb in field and lab studies. The results showed moderate to strong correlations (R(2)=0.84-0.99) between all body parts and cloacal temperature. However, despite the readings on the tail base showed the strongest correlation in all three species, it was the eye where the absolute values and pattern of temperature change most consistently followed the cloacal measurements. Hence, we concluded that the eye would be the body location whose IR camera readings more closely approximate that of the animal's internal environment. Alternatively, other body parts can be used, provided that a careful calibration is carried out. We provide guidelines for future research using thermography to infer Tb of lizards.

  5. Parsec-scale jet precession in BL Lacertae (2200+420)

    OpenAIRE

    Caproni, Anderson; Abraham, Zulema; Monteiro, Hektor

    2012-01-01

    BL Lacertae is the prototype of the BL Lac class of active galactic nuclei, exhibiting intensive activity on parsec (pc) scales, such as intense core variability and multiple ejections of jet components. In particular, in previous works the existence of precession motions in the pc-scale jet of BL Lacertae has been suggested. In this work we revisit this issue, investigating temporal changes of the observed right ascension and declination offsets of the jet knots in terms of our relativistic ...

  6. Fontainebleau Sand

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    2006-01-01

    The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand.......The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand....

  7. Trapper readies trap for lizard

    Science.gov (United States)

    2000-01-01

    State-licensed animal trapper James Dean sets the open door of an animal trap on KSC. He hopes to catch a large monitor lizard spotted recently near S.R. 3, a route into the Center, by several area residents. The lizard is not a native of the area, and possibly a released pet. Dean is working with the cooperation of KSC and the Merritt Island National Wildlife Refuge.

  8. Causes of habitat divergence in two species of agamid lizards in arid central Australia.

    Science.gov (United States)

    Daly, Benjamin G; Dickman, Chris R; Crowther, Mathew S

    2008-01-01

    The deserts of central Australia contain richer communities of lizards than any other arid regions, with the highest diversity occurring in sand dune habitats dominated by hummock-forming spinifex grasses. To investigate the mechanisms that permit coexistence, we studied two species of coexisting agamid lizards that exhibit striking divergence in their use of habitat in the Simpson Desert of central Australia. Here, the military dragon Ctenophorus isolepis is restricted primarily to sites providing > 30% cover of hard spinifex Triodia basedowii, whereas the central netted dragon C. nuchalis occurs in areas with much sparser (thermal environments or different prey types and that each selects the habitats that maximize access to them. Both were supported. C. isolepis preferred lower temperatures when active and specialized in eating ants ecological interactions, allowing lizard species to partition biotic and abiotic resources and achieve the extraordinarily high levels of local diversity that are observed.

  9. Muscle fiber-type variation in lizards (Squamata) and phylogenetic reconstruction of hypothesized ancestral states.

    Science.gov (United States)

    Bonine, Kevin E; Gleeson, Todd T; Garland, Theodore

    2005-12-01

    Previously, we found that phrynosomatid lizards, a diverse group common in the southwestern USA, vary markedly in fiber-type composition of the iliofibularis (a hindlimb muscle important in locomotion). Phrynosomatidae comprises three subclades: the closely related sand and horned lizards, and their relatives the Sceloporus group. The variation in muscle fiber-type composition for 11 phrynosomatid species is attributable mainly to differences between the sand- and horned-lizard subclades. Here, we expand the phrynosomatid database with three additional species and compare these results with data collected for 10 outgroup (distantly related) species. Our goal was to determine if the patterns found in Phrynosomatidae hold across a broader phylogenetic range of the extant lizards and to elucidate the evolution of muscle fiber-type composition and related traits. To allow for meaningful comparisons, data were collected from species that are primarily terrestrial and relatively small in size (3.5-65 g body mass). Results indicate that the fiber-type variation observed within the Phrynosomatidae almost spans the range of variation observed in our sample of 24 species from eight families. However, one species of Acanthodactylus (Lacertidae) had a consistent region of large tonic fibers (that did not stain darkly for either succinic dehydrogenase or myosin ATPase activity), a fiber-type only occasionally seen in the other 23 species examined. Many species have a large proportion of either fast-twitch glycolytic (FG; e.g. sand lizards and Aspidoscelis) or fast-twitch oxidative-glycolytic (FOG) fibers (e.g. horned lizards), with the slow-oxidative proportion occupying only 1-17% of the iliofibularis. Importantly, the negative relationship between FG and FOG composition observed in Phrynosomatidae appears to be a characteristic of lizards in general, and could lead to functional trade-offs in aspects of locomotor performance, as has previously been reported for Lacertidae

  10. spatial distribution pattern of the steppe toad-headed lizard (phrynocephalus frontalis) and its influencing factors

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    spatial distribution patterns are associated with life history and behavioral adaptations of animals.for studying the spatial distribution pattern of the steppe toad-headed lizard (phrynocephalusfrontalis) and its influencing factors,we conducted experiments in hunshandake sandy land in inner mongolia,china in july 2009.by calculating the clustered indices,we found that the lizard was aggregately distributed when the sampling quadrat was smaller than 10 m × 10 m,and uniformly distributed when it was greater than 10 m × 10 m.the nearest neighbor rule showed a clustering distribution pattern for p frontalis and the distribution pattern was quadrat-sampling dependent.furthermore,the cluster was determined by environmental factors when the sampling quadrat was smaller than 20 m × 20 m,but it was determined by both environmental factors and characteristics of the lizard when it was larger than 20 m × 20 m.our results suggested that the steppe toad-headed lizards tended to aggregate into suitable habitat patches in desert areas.additionally,we discussed that the lizard aggregation could be potentially used as an indictor of movement of sand dunes.

  11. Understanding lizard's microhabitat use based on a mechanistic model of behavioral thermoregulation

    Science.gov (United States)

    Fei, Teng; Venus, Valentijn; Toxopeus, Bert; Skidmore, Andrew K.; Schlerf, Martin; Liu, Yaolin; van Overdijk, Sjef; Bian, Meng

    2008-12-01

    Lizards are an "excellent group of organisms" to examine the habitat and microhabitat use mainly because their ecology and physiology is well studied. Due to their behavioral body temperature regulation, the thermal environment is especially linked with their habitat use. In this study, for mapping and understanding lizard's distribution at microhabitat scale, an individual of Timon Lepidus was kept and monitored in a terrarium (245×120×115cm) in which sand, rocks, burrows, hatching chambers, UV-lamps, fog generators and heating devices were placed to simulate its natural habitat. Optical cameras, thermal cameras and other data loggers were fixed and recording the lizard's body temperature, ground surface temperature, air temperature, radiation and other important environmental parameters. By analysis the data collected, we propose a Cellular Automata (CA) model by which the movement of lizards is simulated and translated into their distribution. This paper explores the capabilities of applying GIS techniques to thermoregulatory activity studies in a microhabitat-scale. We conclude that microhabitat use of lizards can be explained in some degree by the rule based CA model.

  12. Acoustical coupling of lizard eardrums

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, Jakob; Manley, Geoffrey A

    2008-01-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and...

  13. [The orbitotemporal region in the cranium of Chelydra serpentina Linnaeus (Chelonia) and Lacerta sicula Rafinesque (Lacertilia)].

    Science.gov (United States)

    Rieppel, O

    1976-01-01

    An analysis of the ontogenesis of the chondrocranium gives the following homologies in the skull of Lacerta and Chelydra: (see article). It is shown that the extracranial position of the cavum epiptericum in Lacerta corresponds to the stage of maximal development of the chondrocranium in Chelydra. But further development brings about a dermal sidewall in the orbitotemporal region, b,ilt up by descending parietal flanges which incorporate the epipterygoid. This not only allows the pila antotica to degenerate but also incorporates the cavum in the cranial cavity.

  14. Relativistic Beaming and Orientation Effects in BL Lacertae Objects

    Indian Academy of Sciences (India)

    F. C. Odo; A. A. Ubachukwu; A. E. Chukwude

    2012-09-01

    We use the correlation between the core-to-lobe radio luminosity ratio () and the linear size () of a sample of BL Lacertae objects to investigate the relativistic beaming and radio source orientation paradigm for high peaked and low-peaked BL Lacs (X-ray and radio selected BL Lacs respectively) and to constrain relativistic beaming model for this extreme class of active galactic nuclei. We show that the - distributions of the BL Lac populations contradict blazar orientation sequence, with the X-ray selected BL Lacs (XBLs) being more consistent with the beaming and orientation model. On the premise that Fanaroff-Riley Type I radio galaxies are the unbeamed parent population of these objects, we derive the bulk Lorentz factor of the jets, ∼ 7-20 corresponding to a critical cone angle for optimum boosting, c of ∼ 1° - 4°, while on average, these objects are inclined at 5° - 12° to the line-of-sight. The implications of these results for the blazar unification sequence are discussed.

  15. On the relationship between BL Lacertae objects and radio galaxies

    CERN Document Server

    Landt, Hermine

    2008-01-01

    We present deep radio images at 1.4 GHz of a large and complete sample of BL Lacertae objects (BL Lacs) selected from the Deep X-ray Radio Blazar Survey (DXRBS). We have observed 24 northern sources with the Very Large Array (VLA) in both its A and C configurations and 15 southern sources with the Australia Telescope Compact Array (ATCA) in its largest configuration. We find that in the DXRBS, as in the 1-Jy survey, which has a radio flux limit roughly ten times higher than the DXRBS, a considerable number (about a third) of BL Lacs can be identified with the relativistically beamed counterparts of Fanaroff-Riley type II (FR II) radio galaxies. We attribute the existence of FR II-BL Lacs, which is not accounted for by current unified schemes, to an inconsistency in our classification scheme for radio-loud active galactic nuclei (AGN). Taking the extended radio power as a suitable measure of intrinsic jet power, we find similar average values for low- (LBL) and high-energy peaked BL Lacs (HBL), contrary to the...

  16. BL Lacertae Objects and the Extragalactic Gamma-Ray Background

    CERN Document Server

    Li, Fan

    2011-01-01

    A tight correlation between gamma-ray and radio emission is found for a sample of BL Lacertae (BL Lac) objects detected by Fermi Gamma-ray Space Telescope (Fermi) and the Energetic Gamma-Ray Experiment Telescope (EGRET). The gamma-ray emission of BL Lac objects exhibits strong variability, and the detection rate of gamma-ray BL Lac objects is low, which may be related to the gamma-ray duty cycle of BL Lac objects. We estimate the gamma-ray duty cycle ~ 0.11, for BL Lac objects detected by EGRET and Fermi. Using the empirical relation of gamma-ray emission with radio emission and the estimated gamma-ray duty cycle, we derive the gamma-ray luminosity function (LF) of BL Lac objects from their radio LF. Our derived gamma-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei (AGN) sample. We find that about 45% of the extragalactic diffuse gamma-ray background (EGRB) is contributed by BL Lac objects. Combining the estimate of the quasar contri...

  17. Infrared Variation of Radio Selected BL Lacertae Objects

    CERN Document Server

    Lin, R G

    1999-01-01

    In this paper, the historical infrared (JHK) data compiled from the published literature are presented in electronic form for 40 radio selected BL Lacertae objects (RBLs) for the first time. Largest variations are found and compared with the largest optical variation. Relations between color index and magnitude and between color-color indices are discussed individually. For the color-magnitude relation, some objects (0048-097, 0735+178, 0851+202, 1215+303, 1219+285, 1749+096, and perhaps 0219+428, 0537-441, 1514-241) show that color index increases with magnitude indicating that the spectrum flattens when the source brightens while some other objects (0754+100, 1147+245, 1418+546, and 1727+502) perhaps show an opposite behaviour, while remaining objects do not show any clear tendency; For color-color relation, it is found common that (J-K) is closely correlated with (J-H) while (J-H) is not correlated with (H-K).

  18. Another look at the BL Lacertae flux and spectral variability

    CERN Document Server

    Raiteri, C M; Bruschini, L; Capetti, A; Kurtanidze, O M; Larionov, V M; Romano, P; Vercellone, S; Agudo, I; Aller, H D; Aller, M F; Arkharov, A A; Bach, U; Berdyugin, A; Blinov, D A; Böttcher, M; Buemi, C S; Calcidese, P; Carosati, D; Casas, R; Chen, W -P; Coloma, J; Diltz, C; Di Paola, A; Dolci, M; Efimova, N V; Forné, E; Gómez, J L; Gurwell, M A; Hakola, A; Hovatta, T; Hsiao, H Y; Jordan, B; Jorstad, S G; Koptelova, E; Kurtanidze, S O; Lähteenmäki, A; Larionova, E G; Leto, P; Lindfors, E; Ligustri, R; Marscher, A P; Morozova, D A; Nikolashvili, M G; Nilsson, K; Ros, J A; Roustazadeh, P; Sadun, A C; Sillanpää, A; Sainio, J; Takalo, L O; Tornikoski, M; Trigilio, C; Troitsky, I S; Umana, G

    2010-01-01

    The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distri...

  19. The Multi-periodic Blazhko Modulation of CZ Lacertae

    CERN Document Server

    Sódor, Á; Szeidl, B; Váradi, M; Henden, A; Vida, K; Hurta, Zs; Posztobányi, K; Dékány, I; Szing, A

    2010-01-01

    Thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae is presented. The observations were carried out in two consecutive observing seasons in 2004 and 2005 within the framework of the Konkoly Blazhko Survey of bright, northern, short-period RRab variables. The O-C variation of CZ Lac indicated that a significant period decrease took place just around the time of the CCD observations. Our data gave a unique opportunity to study the related changes in the pulsation and modulation properties of a Blazhko star in detail. Two different period components ($\\approx$14.6 d and $\\approx$18.6 d) of the Blazhko modulation were identified. Both modulation components had similar strength. The periods and amplitudes of the modulations changed significantly from the first season to the next, meanwhile, the mean pulsation amplitude slightly decreased. The modulation frequencies were in a 5:4 resonance ratio in the first observing season then the frequencies shifted in opposite direction...

  20. The long-term optical spectral variability of BL Lacertae

    CERN Document Server

    Papadakis, I E; Raiteri, C M

    2007-01-01

    We present the results from a study of the long-term optical spectral variations of BL Lacertae, using the long and well-sampled B and R-band light curves of the Whole Earth Blazar Telescope (WEBT) collaboration, binned on time intervals of 1 day. The relation between spectral slope and flux (the spectrum gets bluer as the source flux increases) is well described by a power-law model, although there is significant scatter around the best-fitting model line. To some extent, this is due to the spectral evolution of the source (along well-defined loop-like structures) during low-amplitude events, which are superimposed on the major optical flares, and evolve on time scales of a few days. The "bluer-when-brighter" mild chromatism of the long-term variations of the source can be explained if the flux increases/decreases faster in the B than in the R band. The B and R-band variations are well correlated, with no significant, measurable delays larger than a few days. On the other hand, we find that the spectral vari...

  1. Broadband Spectra and Variability of BL Lacertae in 2000

    CERN Document Server

    Böttcher, M; Aller, M F; Mang, O; Raiteri, C M; Ravasio, M; Tagliaferri, G; Teraesranta, H; Villata, M

    2002-01-01

    We have organized an extensive multiwavelength campaign on BL Lacertae in the second half of 2000. Simultaneous or quasi-simultaneous observations were taken at radio frequencies, in the optical - carried out by the WEBT collaboration -, in X-rays - using BeppoSAX and RXTE -, and at VHE gamma-rays with the CAT and HEGRA Cherenkov telescope facilities. In this paper, we are presenting first results from this campaign. The WEBT optical campaign achieved an unprecedented time coverage, virtually continuous over several 10 - 20 hour segments, and revealed intraday variability on time scales of ~ 1.5 hours. The X-ray observations of Nov. 1 - 2, 2000, revealed significant variability on similar time scales, and provided evidence for the synchrotron spectrum extending out to ~ 10 keV during that time. At higher energies, the onset of the hard power-law commonly observed in radio-loud quasars and radio-selected BL Lac objects is seen. From the energy-resolved X-ray variability patterns, we find evidence that electron...

  2. The WEBT BL Lacertae Campaign 2001 and its extension

    CERN Document Server

    Villata, M; Kurtanidze, O M; Nikolashvili, M G; Ibrahimov, M A; Papadakis, I E; Tosti, G; Hroch, F; Takalo, L O; Sillanpää, A; Hagen-Thorn, V A; Larionov, V M; Schwartz, R D; Basler, J; Brown, L F; Balonek, T J; Benítez, E; Ramírez, A; Sadun, A C; Boltwood, P; Carini, M T; Barnaby, D; Coloma, J M; Ros, J A; Dai, B Z; Xie, G Z; Mattox, J R; Rodríguez, D; Asfandiyarov, I M; Atkerson, A; Beem, J L; Bloom, S D; Chanturiya, S M; Ciprini, S; Crapanzano, S; De Diego, J A; Efimova, N V; Gardiol, D; Guerra, J C; Kahharov, B B; Kapanadze, B Z; Karttunen, H; Kato, T; Kimeridze, G N; Kudryavtseva, N A; Lainela, M; Lanteri, L; Larionova, E G; Maesano, M; Marchili, N; Massone, G; Monroe, T; Montagni, F; Nesci, R; Nilsson, K; Noble, J C; Nucciarelli, G; Ostorero, L; Papamastorakis, J; Pasanen, M; Peters, C S; Pursimo, T; Reig, P; Ryle, W; Sclavi, S; Sigua, L A; Uemura, M; Wills, W

    2004-01-01

    BL Lacertae has been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present $UBVRI$ light curves obtained by the WEBT from 1994 to 2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the $\\sim 15600$ observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a few-day time scale appear as mildly-chromatic events, while a strong bluer-when-brighter chromatism characterizes very fast (intraday) flares. By decoupling the two components, we quantify the degree of chromatism inferring that longer-term flux changes imply moving along a $\\sim 0.1$ bluer-when-brighter slope in the $B-R$ vers...

  3. Random Sampling of Squamate Reptiles in Spanish Natural Reserves Reveals the Presence of Novel Adenoviruses in Lacertids (Family Lacertidae and Worm Lizards (Amphisbaenia.

    Directory of Open Access Journals (Sweden)

    Leonóra Szirovicza

    Full Text Available Here, we report the results of a large-scale PCR survey on the prevalence and diversity of adenoviruses (AdVs in samples collected randomly from free-living reptiles. On the territories of the Guadarrama Mountains National Park in Central Spain and of the Chafarinas Islands in North Africa, cloacal swabs were taken from 318 specimens of eight native species representing five squamate reptilian families. The healthy-looking animals had been captured temporarily for physiological and ethological examinations, after which they were released. We found 22 AdV-positive samples in representatives of three species, all from Central Spain. Sequence analysis of the PCR products revealed the existence of three hitherto unknown AdVs in 11 Carpetane rock lizards (Iberolacerta cyreni, nine Iberian worm lizards (Blanus cinereus, and two Iberian green lizards (Lacerta schreiberi, respectively. Phylogeny inference showed every novel putative virus to be a member of the genus Atadenovirus. This is the very first description of the occurrence of AdVs in amphisbaenian and lacertid hosts. Unlike all squamate atadenoviruses examined previously, two of the novel putative AdVs had A+T rich DNA, a feature generally deemed to mirror previous host switch events. Our results shed new light on the diversity and evolution of atadenoviruses.

  4. Negative correlation between nuptial throat colour and blood parasite load in male European green lizards supports the Hamilton-Zuk hypothesis.

    Science.gov (United States)

    Molnár, Orsolya; Bajer, Katalin; Mészáros, Boglárka; Török, János; Herczeg, Gábor

    2013-06-01

    During female mate choice, conspicuous male sexual signals are used to infer male quality and choose the best sire for the offspring. The theory of parasite-mediated sexual selection (Hamilton-Zuk hypothesis) presumes that parasite infection can influence the elaboration of sexual signals: resistant individuals can invest more energy into signal expression and thus advertise their individual quality through signal intensity. By preferring these males, females can provide resistance genes for their offspring. Previous research showed that nuptial throat colour of male European green lizard, Lacerta viridis, plays a role in both inter- and intrasexual selections as a condition-dependent multiple signalling system. The aim of this study was to test the predictions of the Hamilton-Zuk hypothesis on male European green lizards. By blood sampling 30 adult males during the reproductive season, we found members of the Haemogregarinidae family in all but one individual (prevalence = 96%). The infection intensity showed strong negative correlation with the throat and belly colour brightness in line with the predictions of the Hamilton-Zuk hypothesis. In addition, we found other correlations between infection intensity and other fitness-related traits, suggesting that parasite load has a remarkable effect on individual fitness. This study shows that throat patch colour of the European green lizards not only is a multiple signalling system but also possibly acts as an honest sexual signal of health state in accordance with the Hamilton-Zuk hypothesis.

  5. Direct and indirect effects of petroleum production activities on the western fence lizard (Sceloporus occidentalis) as a surrogate for the dunes sagebrush lizard (Sceloporus arenicolus).

    Science.gov (United States)

    Weir, Scott M; Knox, Ami; Talent, Larry G; Anderson, Todd A; Salice, Christopher J

    2016-05-01

    The dunes sagebrush lizard (Sceloporus arenicolus) is a habitat specialist of conservation concern limited to shin oak sand dune systems of New Mexico and Texas (USA). Because much of the dunes sagebrush lizard's habitat occurs in areas of high oil and gas production, there may be direct and indirect effects of these activities. The congeneric Western fence lizard (Sceloporus occidentalis) was used as a surrogate species to determine direct effects of 2 contaminants associated with oil and gas drilling activities in the Permian Basin (NM and TX, USA): herbicide formulations (Krovar and Quest) and hydrogen sulfide gas (H2S). Lizards were exposed to 2 concentrations of H2 S (30 ppm or 90 ppm) and herbicide formulations (1× or 2× label application rate) representing high-end exposure scenarios. Sublethal behavioral endpoints were evaluated, including sprint speed and time to prey detection and capture. Neither H2S nor herbicide formulations caused significant behavioral effects compared to controls. To understand potential indirect effects of oil and gas drilling on the prey base, terrestrial invertebrate biomass and order diversity were quantified at impacted sites to compare with nonimpacted sites. A significant decrease in biomass was found at impacted sites, but no significant effects on diversity. The results suggest little risk from direct toxic effects, but the potential for indirect effects should be further explored.

  6. Production and glycosylation of sperm constitutive proteins in the lizard Lacerta vivipara. Evolution during the reproductive period.

    Science.gov (United States)

    Depeiges, A; Force, A; Dufaure, J P

    1987-01-01

    From epididymal fluid samples taken at three different times during the reproductive period (early April, late April, mid-May), the soluble proteins were separated with one dimensional electrophoresis on polyacrylamide gel. Their evolution was studied: firstly quantitatively, after staining with Coomassie blue, or, for one protein (the "L" protein), by immunodetection; secondly, according to their glycosylation after transfer to nitrocellulose and treatment with a set of labelled lectins: from Wheat germ, Ricinus communis, Lens culinaris, Asparagus pea or Canavalia ensiformis, with or without use of their specific inhibitor sugars. At least 15 proteins underwent a quantitative and/or qualitative evolution, mainly during the month of April. Protein "L" (19 kDa), which is androgen dependent and which fixates on to spermatozoa during their epididymal transit, appears to be little or not glycosylated. By contrast its accumulation in the epididymal canal increases considerably during the month of April. Five other proteins proved to be especially interesting because of their evolution during this same period, notably the MW 94, 67, 35, 29 and 25.5 kDa proteins. With the exception of the 67 kDa all the others increased quantitatively. All were decisively enriched in mannose or in methyl-mannoside residues. The proteins of MW 29 and 25.5 kDa were also enriched in galactose or N-acetyl galactosamine residues. These findings are of physiological significance since they are set up concomitantly with the acquisition of maximum motility of spermatozoa in the distal segment of the epididymis, and they coincide with a very great increase in testosteronemia.

  7. Now you see me, now you don't: iridescence increases the efficacy of lizard chromatic signals

    Science.gov (United States)

    Pérez i de Lanuza, Guillem; Font, Enrique

    2014-10-01

    The selective forces imposed by primary receivers and unintended eavesdroppers of animal signals often act in opposite directions, constraining the development of conspicuous coloration. Because iridescent colours change their chromatic properties with viewer angle, iridescence offers a potential mechanism to relax this trade-off when the relevant observers involved in the evolution of signal design adopt different viewer geometries. We used reflectance spectrophotometry and visual modelling to test if the striking blue head coloration of males of the lizard Lacerta schreibeiri (1) is iridescent and (2) is more conspicuous when viewed from the perspective of conspecifics than from that of the main predators of adult L. schreibeiri (raptors). We demonstrate that the blue heads of L. schreiberi show angle-dependent changes in their chromatic properties. This variation allows the blue heads to be relatively conspicuous to conspecific viewers located in the same horizontal plane as the sender, while simultaneously being relatively cryptic to birds that see it from above. This study is the first to suggest the use of angle-dependent chromatic signals in lizards, and provides the first evidence of the adaptive function of iridescent coloration based on its detectability to different observers.

  8. BL Lacertae objects and the extragalactic γ-ray background

    Institute of Scientific and Technical Information of China (English)

    Fan Li; Xin-Wu Cao

    2011-01-01

    A tight correlation between γ-ray and radio emission is found for a sample of BL Lacertae (BL Lac) objects detected by the Fermi Gamma-ray Space Telescope (Fermi) and the Energetic Gamma-Ray Experiment Telescope (EGRET).The γ-ray emission of BL Lac objects exhibits strong variability,and the detection rate of γ-ray BL Lac objects is low,which may be related to the γ-ray duty cycle of BL Lac objects.We estimate the γ-ray duty cycle,δγ (≌)0.11,for BL Lac objects detected by EGRET and Fermi.Using the empirical relation ofγ-ray emission with radio emission and the estimated γ-ray duty cycle δγ,we derive the γ-ray luminosity function (LF) of BL Lac objects from their radio LF.Our derived γ-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei (AGN) sample.Comparison of the derived LF of the γ-ray BL Lac objects in this work with that derived by Abdo et al.(2009a) requires the γ-ray duty cycle of BL Lac objects to be almost luminosity-independent.We find that ~ 45% of the extragalactic diffuse γ-ray background (EGRB) is contributed by BL Lac objects.Combining the estimate of the quasar contribution to the EGRB in the previous work,we find that ~ 77% of the EGRB is contributed by BL Lac objects and radio quasars.

  9. Ultrastructural study of the epithelial mucous cells in lizards (Lacertilia).

    Science.gov (United States)

    Martín-Lacave, I; Montero, C; López-Muñoz, J M; López-Campos, J L; Galera, H

    1982-01-01

    An ultrastructural study of the mucous cells of the intestinal epithelium of four lacertilian species (Lacerta lepida, Lacerta hispanica, Psammodromus algirus and Acanthodactylus erythrurus) is here reported. Two types of mucous cells have been found in these species: common mucous cells and granular mucous cells. Immature and mature forms of both types have been observed. The common mucous cells or typical goblet cells have the same characteristics in all four species. The granules of the granular mucous cells of the two species of lacerta are similar but differ from those of the other two species.

  10. Condition dependence of reproductive strategy and the benefits of polyandry in a viviparous lizard.

    Science.gov (United States)

    Eizaguirre, Christophe; Laloi, David; Massot, Manuel; Richard, Murielle; Federici, Pierre; Clobert, Jean

    2007-02-07

    Species in which males do not contribute to reproduction beyond the provision of sperm offer good opportunities to study the potential genetic benefits that females can obtain from polyandry. Here, we report the results of a study examining the relationships between polyandry and components of female fitness in the common lizard (Lacerta vivipara). We found that polyandrous females produce larger clutches than monandrous females. Polyandrous females also lose fewer offspring during the later stages of gestation and at birth, but we did not find any relationship between polyandry and physical characteristics of viable neonates. Our results were consistent with the predictions of the intrinsic male quality hypothesis, while inbreeding avoidance and genetic incompatibility avoidance might also explain some part of the variation observed in clutch size. Moreover, the benefits of polyandry appeared to depend on female characteristics, as revealed by an interaction between reproductive strategy and female length on reproductive success. Thus, all females did not benefit equally from mating with multiple males, which could explain why polyandry and monandry coexist.

  11. Temperature, activity, and lizard life histories.

    Science.gov (United States)

    Adolph, S C; Porter, W P

    1993-08-01

    Lizard life-history characteristics vary widely among species and populations. Most authors seek adaptive or phylogenetic explanations for life-history patterns, which are usually presumed to reflect genetic differences. However, lizard life histories are often phenotypically plastic, varying in response to temperature, food availability, and other environmental factors. Despite the importance of temperature to lizard ecology and physiology, its effects on life histories have received relatively little attention. We present a theoretical model predicting the proximate consequences of the thermal environment for lizard life histories. Temperature, by affecting activity times, can cause variation in annual survival rate and fecundity, leading to a negative correlation between survival rate and fecundity among populations in different thermal environments. Thus, physiological and evolutionary models predict the same qualitative pattern of life-history variation in lizards. We tested our model with published life-history data from field studies of the lizard Sceloporus undulatus, using climate and geographical data to reconstruct estimated annual activity seasons. Among populations, annual activity times were negatively correlated with annual survival rate and positively correlated with annual fecundity. Proximate effects of temperature may confound comparative analyses of lizard life-history variation and should be included in future evolutionary models.

  12. Lizard locomotion in heterogeneous granular media

    Science.gov (United States)

    Schiebel, Perrin; Goldman, Daniel

    2014-03-01

    Locomotion strategies in heterogeneous granular environments (common substrates in deserts), are relatively unexplored. The zebra-tailed lizard (C. draconoides) is a useful model organism for such studies owing to its exceptional ability to navigate a variety of desert habitats at impressive speed (up to 50 body-lengths per second) using both quadrapedal and bidepal gaits. In laboratory experiments, we challenge the lizards to run across a field of boulders (2.54 cm diameter glass spheres or 3.8 cm 3D printed spheres) placed in a lattice pattern and embedded in a loosely packed granular medium of 0.3 mm diameter glass particles. Locomotion kinematics of the lizard are recorded using high speed cameras, with and without the scatterers. The data reveals that unlike the lizard's typical quadrupedal locomotion using a diagonal gait, when scatterers are present the lizard is most successful when using a bipedal gait, with a raised center of mass (CoM). We propose that the kinematics of bipedal running in conjunction with the lizard's long toes and compliant hind foot are the keys to this lizard's successful locomotion in the presence of such obstacles. NSF PoLS

  13. Unique Structural Features Facilitate Lizard Tail Autotomy

    DEFF Research Database (Denmark)

    Sanggaard, Kristian Wejse; Danielsen, C. C.; Wogensen, L.

    2012-01-01

    Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed...... that tail shedding by the Tokay gecko (Gekko gecko) and the associated extracellular matrix (ECM) rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail...

  14. Trappers set up trap for lizard

    Science.gov (United States)

    2000-01-01

    In hope of catching a large monitor lizard seen in the area, state-licensed animal trappers Dewey Kessler and James Dean (at left), with Gary Povitch (kneeling) of the U.S. Wildlife and Dan Turner (standing) set up a trap on KSC. The lizard has been spotted recently near S.R. 3, a route into the Center, by several area residents. Turner is a monitor expert. The lizard is not a native of the area, and possibly a released pet. Dean is working with the cooperation of KSC and the Merritt Island National Wildlife Refuge.

  15. Estudio de variabilidad del blazar BL Lacertae: desde radio hasta rayos gamma (2008-2015)

    Science.gov (United States)

    Pichel, A.; Rovero, A. C.

    2016-08-01

    The aim of this work is to study the blazar BL Lacertae during extended periods (greater than weeks), by characterizing the changes in flux and polarization at optical, radio, X-rays and gamma rays; also to investigate the possible correlations between different bands. We look for periodicity in the flux variations in different bands, looking for criteria to predict high activity states of the source. We use multi-frequency observations of BL Lacertae obtained during the years 2008--2015, from radio to very-high-energy gamma rays. During this period, the source remained mainly in a low state of activity at the high energy bands, with several episodes of high activity (flares) in different bands, some of them observed simultaneously in several bands.

  16. 37 GHz observations of a large sample of BL Lacertae objects

    CERN Document Server

    Nieppola, E; Lähteenmäki, A; Valtaoja, E; Hakala, T; Hovatta, T; Kotiranta, M; Nummila, S; Ojala, T; Parviainen, M; Ranta, M; Saloranta, P -M; Torniainen, I; Tröller, M; 10.1086/512609

    2009-01-01

    We present 37 GHz data obtained at Metsahovi Radio Observatory in 2001 December - 2005 April for a large sample of BL Lacertae objects. We also report the mean variability indices and radio spectral indices in frequency intervals 5 - 37 GHz and 37 - 90 GHz. Approximately 34 % of the sample was detected at 37 GHz, 136 BL Lacertae objects in all. A large majority of the detected sources were low-energy BL Lacs (LBLs). The variability index values of the sample were diverse, the mean fractional variability of the sample being \\Delta S_2 = 0.31. The spectral indices also varied widely, but the average radio spectrum of the sample sources is flat. Our observations show that many of the high-energy BL Lacs (HBL), which are usually considered radio-quiet, can at times be detected at 37 GHz.

  17. The connection between black hole mass and Doppler boosted emission in BL Lacertae type objects

    OpenAIRE

    Leon-Tavares, J.; Valtaoja, E.; V. H. Chavushyan; Tornikoski, M.; Anorve, C.; Nieppola, E.; Lahteenmaki, A.

    2010-01-01

    We investigate the relationship between black hole mass (MBH) and Doppler boosted emission for BL Lacertae type objects (BL Lacs) detected in the SDSS and FIRST surveys. The synthesis of stellar population and bidimensional decomposition methods allows us to disentangle the components of the host galaxy from that of the nuclear black hole in their optical spectra and images, respectively. We derive estimates of black hole masses via stellar velocity dispersion and bulge luminosity. We find th...

  18. Optically Identified BL Lacertae Objects From the Sloan Digital Sky Survey

    Science.gov (United States)

    2007-11-02

    386 BL Lacertae candidates identified from 2860 deg2 of the Sloan Digital Sky Survey ( SDSS ) spectroscopic database. The candidates are primarily...selected to have quasi-featureless optical spectra and low proper motions as measured from SDSS and USNO-B positions; however, our ability to separate...Sky Survey ( SDSS ; York et al. 2000) and the Two-Degree Field QSO Red- shift Survey (2QZ; Boyle et al. 2000), have the potential to reveal new

  19. Long-Term Optical Spectra Variability of BL Lacertae Object S5 0716+714

    Indian Academy of Sciences (India)

    Zhang Hao Jing; Zhao Gang; Zhang Xiong; Bai Jing Ming; Tang Ling; Xu Yun Bing

    2011-03-01

    Based on the long-term data from observations, we present an evidence for its spectral index variability behaviour in optical bands for BL Lacertae object S5 0716+714.We find that the spectral index variability period is in agreement with the flux variability period of about 1180 days in optical bands.We also find that the spectral index variability has periods of about 71 and 60 days which cannot be compared with the amplitude of long-term variability.

  20. Optical polarimetry and photometry of X-ray selected BL Lacertae objects

    Science.gov (United States)

    Jannuzi, Buell T.; Smith, Paul S.; Elston, Richard

    1993-01-01

    We present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects. The monitored objects include a complete sample drawn from the Einstein Extended Medium Sensitivity Survey. We confirm the BL Lac identifications for 15 of these 22 objects. We include descriptions of the objects and samples in our monitoring program and of the existing complete samples of BL Lac objects, highly polarized quasars, optically violent variable quasars, and blazars.

  1. Sands styrke

    DEFF Research Database (Denmark)

    Jacobsen, H. Moust; Jørgensen, Mogens B.; Poulsen, H. Serup

    1975-01-01

    På grundlag af triaxialforsøg med D=7 og 20 cm og varierende højde på løse og faste lejringer af Blokhussand kan effekten af varierende højde-breddeforhold og spændingsniveau samt skalaeffekten bestemmes. Ved sammenligning med pladeforsøg med overfladelast op til 8 t/m2 kan den almindelige fremga...... fremgangsmåde ved bæreevneberegninger på sand undersøges....

  2. Parsec-scale jet precession in BL Lacertae (2200+420)

    Science.gov (United States)

    Caproni, A.; Abraham, Z.; Monteiro, H.

    2013-01-01

    BL Lacertae is the prototype of the BL Lac class of active galactic nuclei, exhibiting intensive activity on parsec (pc) scales, such as intense core variability and multiple ejections of jet components. In particular, in previous works the existence of precession motions in the pc-scale jet of BL Lacertae has been suggested. In this work we revisit this issue, investigating temporal changes of the observed right ascension and declination offsets of the jet knots in terms of our relativistic jet-precession model. The seven free parameters of our precession model were optimized via a heuristic cross-entropy method, comparing the projected precession helix with the positions of the jet components on the plane of the sky and imposing constraints on their maximum and minimum superluminal velocities. Our optimized best model is compatible with a jet having a bulk velocity of 0.9824c, which is precessing with a period of about 12.1 yr in the observer's reference frame and changing its orientation in relation to the line of sight between 4° and 5°, approximately. Assuming that the jet precession has its origin in a supermassive binary black hole system, we show that the 2.3-yr periodic variation in the structural position angle of the very-long-baseline interferometry (VLBI) core of BL Lacertae reported by Stirling et al. is compatible with a nutation phenomenon if the secondary black hole has a mass higher than about six times that of the primary black hole.

  3. Analyses of the Light Variations of OJ 287, 0716+714 and BL Lacertae

    Science.gov (United States)

    Wang, Hong-tao; Pan, Yan-ping

    2013-01-01

    OJ 287 is a BL Lac object which exhibits intense activities of low peak-frequencies. Its energy spectrum in low frequency band is quite similar with those of two other TeV BL Lac objects (i.e., 0716+714 and BL Lacertae). However, the Cerenkov telescope did not detect its TeV rays. By using the observational data of these three heavenly bodies and comparing the discrepan- cies of their minimal periods of light variations and delays at 22 GHz, 37 GHz and B-waveband, we have further investigated the possible reason why the TeV gamma-rays of OJ 287 have not been observed. The results of analyses are as fol- lows. (1) For the minimal periods of light variations, the periods of OJ 287 at 37 GHZ and B-waveband are short. At 22 GHz the results of OJ 287 and 0716+714 are comparable, but the period of OJ 287 is much shorter in comparison with that of BL Lacertae, and this shows that its activity is more intense. However, the TeV gamma-rays of OJ 287 have not been detected, which implies that the radiation of OJ 287 in TeV waveband may have no connection with the minimal periods of light variations in these three low-energy wavebands. (2) In respect of delays, the delay of OJ 287 in the B waveband with respect to 37 GHz is longer than that of 0716+714, but shorter than that of BL Lacertae. Its delay at 37 GHz in respect to 22 GHz is shorter than that of 0716+714. Meanwhile, the delay of BL Lacertae at 37 GHz in respect to 22 GHz is negative, which implies that 22 GHz precedes 37 GHz. Via the comparison and analysis of delays, no obvious differences between OJ 287 and 0716+714 as well as BL Lacertae have been found. On the side of energy spectra, it is quite possible that due to the steep energy spectrum of OJ 287 in TeV waveband, the Cerenkov telescope has not detected the gamma radiation of OJ 287. However, nowadays it is still not clear whether the steep energy spectrum in TeV energy range has some influence on the light variations in low energy realm.

  4. Temperature, but not available energy, affects the expression of a sexually selected ultraviolet (UV colour trait in male European green lizards.

    Directory of Open Access Journals (Sweden)

    Katalin Bajer

    Full Text Available BACKGROUND: Colour signals are widely used in intraspecific communication and often linked to individual fitness. The development of some pigment-based (e.g. carotenoids colours is often environment-dependent and costly for the signaller, however, for structural colours (e.g. ultraviolet [UV] this topic is poorly understood, especially in terrestrial ectothermic vertebrates. METHODOLOGY/PRINCIPAL FINDINGS: In a factorial experiment, we studied how available energy and time at elevated body temperature affects the annual expression of the nuptial throat colour patch in male European green lizards (Lacerta viridis after hibernation and before mating season. In this species, there is a female preference for males with high throat UV reflectance, and males with high UV reflectance are more likely to win fights. We found that (i while food shortage decreased lizards' body condition, it did not affect colour development, and (ii the available time for maintaining high body temperature affected the development of UV colour without affecting body condition or other colour traits. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that the expression of a sexually selected structural colour signal depends on the time at elevated body temperature affecting physiological performance but not on available energy gained from food per se in an ectothermic vertebrate. We suggest that the effect of high ambient temperature on UV colour in male L. viridis makes it an honest signal, because success in acquiring thermally favourable territories and/or effective behavioural thermoregulation can both be linked to individual quality.

  5. Tar sand

    Energy Technology Data Exchange (ETDEWEB)

    McLendon, T.R.; Bartke, T.C.

    1990-01-01

    Research on tar sand is briefly discussed. The research program supported by the US Department of Energy (DOE) includes a variety of surface extraction schemes. The University of Utah has process development units (PDU) employing fluidized bed, hot, water-assisted, and fluidized-bed/heat-pipe, coupled combustor technology. Considerable process variable test data have been gathered on these systems: (1) a rotary kiln unit has been built recently; (2) solvent extraction processing is being examined; and (3) an advanced hydrogenation upgrading scheme (hydropyrolysis) has been developed. The University of Arkansas, in collaboration with Diversified Petroleum, Inc., has been working on a fatty acid, solvent extraction process. Oleic acid is the solvent/surfactant. Solvent is recovered by adjusting processing fluid concentrations to separate without expensive operations. Western Research Institute has a PDU-scale scheme called the Recycle Oil Pyrolysis and Extraction (ROPE) process, which combines solvent (hot recycle bitumen) and pyrolytic extraction. 14 refs., 19 figs.

  6. Role of amphibians and reptiles in creation of an ecological buffer against technogenic pollution

    Directory of Open Access Journals (Sweden)

    V. L. Bulakhov

    2008-10-01

    Full Text Available It has shown that fossorial activity of common spadefoot Pelobates fuscus (Laurenti, 1768 under conditions of heavy metals pollution of soils is able to reduce the level of the metals in soil. Tropho-metabolic activity (faeces excretion of amphibians (P. fuscus and reptiles (sand lizard Lacerta agilis Linnaeus, 1758 decreases the content of heavy metals in soils.

  7. De duinhagedis voor de toekomst behouden over duinbeheer, versnippering en monitoring

    NARCIS (Netherlands)

    NN,

    1999-01-01

    In the Netherlands the Sand Lizard ( Lacerta agilis Linaeus, 1758) is also called “Dune Lizard”. It is a species of the coastal dunes, although it also appears in inland areas. Its biotope is characterised by geomorphological gradients and small-scale transitions between different types of vegetatio

  8. It's in the sand

    OpenAIRE

    Mitchell, Clive

    2016-01-01

    Sand is sand isn’t it? Sand gets everywhere but rather than a nuisance it is a valuable, high-purity raw material. Clive Mitchell, Industrial Minerals Specialist at the British Geological Survey (BGS), talks us through what sand is, what it can be used for and how to find it. His exploration of sand takes us from the deserts of Arabia to the damp sand pits of Mansfield!

  9. Fanaroff-Riley I galaxies as the parent population of BL Lacertae objects. I. X-ray constraints

    Energy Technology Data Exchange (ETDEWEB)

    Padovani, P.; Urry, C.M. (Space Telescope Science Institute, Baltimore, MD (USA))

    1990-06-01

    The hypothesis that BL Lacertae objects are a special subset of Fanaroff-Riley type I radio galaxies, namely, those dominated by beamed emission from a relativistic jet aligned with the line of sight, is examined by looking at the relative number densities. The calculation depends primarily on observed quantities, including the X-ray luminosity function of Fanaroff-Riley type I galaxies. The model predicts the X-ray luminosity function of BL Lacertae objects, the shape of the X-ray counts below currently observed fluxes, and the velocity of the X-ray emitting jet. With Fanaroff-Riley type I galaxies as the parent population the flat luminosity function, the observed X-ray number counts, and the partial redshift distribution of BL Lacertae objects can be explained. 41 refs.

  10. Controlled preparation of wet granular media reveals limits to lizard burial ability

    Science.gov (United States)

    Sharpe, Sarah S.; Kuckuk, Robyn; Goldman, Daniel I.

    2015-07-01

    Many animals move within ground composed of granular media (GM); the resistive properties of such substrates can depend on water content and compaction, but little is known about how such parameters affect locomotion or the physics of drag and penetration. Using apparatus to control compaction of GM, our recent studies of movement in dry GM have revealed locomotion strategies of specialized dry-sand-swimming reptiles. However, these animals represent a small fraction of the diversity and presumed burial strategies of fossorial reptilian fauna. Here we develop a system to create states of wet GM of varying moisture content and compaction in quantities sufficient to study the burial and subsurface locomotion of the Ocellated skink (C. ocellatus), a generalist lizard. X-ray imaging revealed that in wet and dry GM the lizard slowly buried (≈ 30 s) propagating a wave from head to tail, while moving in a start-stop motion. During forward movement, the head oscillated, and the forelimb on the convex side of the body propelled the animal. Although body kinematics and ‘slip’ were similar in both substrates, the burial depth was smaller in wet GM. Penetration and drag force experiments on smooth cylinders revealed that wet GM was ≈ 4× more resistive than dry GM. In total, our measurements indicate that while the rheology of the dry and wet GM differ substantially, the lizard's burial motor pattern is conserved across substrates, while its burial depth is largely constrained by environmental resistance.

  11. Directional, passive liquid transport: the Texas horned lizard as a model for a biomimetic 'liquid diode'.

    Science.gov (United States)

    Comanns, Philipp; Buchberger, Gerda; Buchsbaum, Andreas; Baumgartner, Richard; Kogler, Alexander; Bauer, Siegfried; Baumgartner, Werner

    2015-08-01

    Moisture-harvesting lizards such as the Texas horned lizard (Iguanidae: Phrynosoma cornutum) live in arid regions. Special skin adaptations enable them to access water sources such as moist sand and dew: their skin is capable of collecting and transporting water directionally by means of a capillary system between the scales. This fluid transport is passive, i.e. requires no external energy, and directs water preferentially towards the lizard's snout. We show that this phenomenon is based on geometric principles, namely on a periodic pattern of interconnected half-open capillary channels that narrow and widen. Following a biomimetic approach, we used these principles to develop a technical prototype design. Building upon the Young-Laplace equation, we derived a theoretical model for the local behaviour of the liquid in such capillaries. We present a global model for the penetration velocity validated by experimental data. Artificial surfaces designed in accordance with this model prevent liquid flow in one direction while sustaining it in the other. Such passive directional liquid transport could lead to process improvements and reduction of resources in many technical applications.

  12. Industrial sand and gravel

    Science.gov (United States)

    Dolley, T.P.

    2013-01-01

    Domestic production of industrial sand and gravel in 2012 was about 49.5 Mt (55 million st), increasing 13 percent compared with that of 2011. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications.

  13. The ecological cost of morphological specialization: feeding by a fossorial lizard.

    Science.gov (United States)

    Andrews, R M; Pough, F H; Collazo, A; de Queiroz, A

    1987-08-01

    Head size and shape of reptiles may reflect selection for multiple uses. For example, sexual selection for large head size may enhance feeding efficiency. In contrast, morphological characteristics of the heads of fossorial reptiles suggests that fossoriality may have evolved at the expense of reduced effectiveness in feeding. Our research focused on the question: Does a fossorial lizard feed less effectively than a non-fossorial lizard? To answer this question, we measured the time, number of bites, and oxygen consumption by sand-swimming (Chalcides ocellatus) and epigeal (Eumeces inexpectatus) skinks feeding on crickets. These lizard species were similar in mass, but different in body form: Chalcides had longer bodies and smaller heads than Eumeces. For lizards of the same mass, Chalcides were unable to eat prey as large as those eaten by Eumeces, Chalcides took longer to eat prey of the same size than did Eumeces, and the aerobic energy cost of eating crickets of the same relative size (cricket mass/lizard mass) tended to be greater for Chalcides than for Eumeces. The ecologically relevant costs of feeding appear to be the upper limit to the size of prey and the time of feeding. Both costs would restrict the energy intake per unit time of Chalcides. Moreover, given the same energy requirements and prey community, Chalcides would have to feed more often and would take longer to feed than would Eumeces. Both factors would increase the exposure of Chalcides to predators relative to that of Eumeces. To reduce the risk of predation, Chalcides would have to reduce energy intake or fulfill its energy requirements with relatively small prey, or both. These conclusions are potentially confounded in two ways. The first is that male Eumeces have relatively large heads as a result of sexual selection. Thus, the differences we observed between Chalcides and Eumeces (most of our specimens were males) could have been the result of reduced costs of feeding for Eumeces due to

  14. AGILE detection of enhanced gamma-ray activity from BL Lacertae

    Science.gov (United States)

    Piano, G.; Pittori, C.; Lucarelli, F.; Verrecchia, F.; Tavani, M.; Minervini, G.; Munar-Adrover, P.; Ursi, A.; Cardillo, M.; Bulgarelli, A.; Fioretti, V.; Zoli, A.; Donnarumma, I.; Vercellone, S.; Striani, E.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Parmiggiani, N.; Ferrari, A.; Paoletti, F.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

    2017-06-01

    AGILE is revealing enhanced gamma-ray activity above 100 MeV from a source positionally consistent with BL Lacertae (HB89 2200+420, z=0.0686). Integrating between 2017-06-04 UT 04:00:00 and 2017-06-06 UT 04:00:00, a preliminary multi-source likelihood analysis detects a gamma-ray flux F( > 100 MeV) = (3.5 +/- 1.0) x 10^-6 photons/cm^2/s with a significance greater than 5 sigma.

  15. Cranial kinesis in gekkonid lizards

    Science.gov (United States)

    Herrel; De Vree F; Delheusy; Gans

    1999-12-01

    Cranial kinesis was studied in two species of gekkonid lizard, Gekko gecko and Phelsuma madagascariensis, using cineradiography and electromyography. The skull of these geckoes showed the three types of kinesis described by Versluys at the beginning of this century: streptostyly, mesokinesis and metakinesis. In accordance with the later model of Frazzetta, the skull of these animals can be modelled by a quadratic crank system: when the mouth opens during feeding, the quadrate rotates forward, the palato-maxillary unit is lifted and the occipital unit swings forward. During jaw closing, the inverse movements are observed; during crushing, the system is retracted beyond its resting position. The data gathered here indicate that the coupled kinesis (streptostyly + mesokinesis) is most prominently present during the capture and crushing cycles of feeding and is largely absent during late intraoral transport, swallowing, drinking and breathing. The electromyographic data indicate a consistent pattern of muscular activation, with the jaw opener and pterygoid protractor always active during the fast opening phase, and the jaw closers active during closing and crushing. Our data generally support the model of Frazzetta. Although the data gathered here do not allow speculation on the functional significance of the kinesis, they clearly provide some key elements required for a further investigation of the functional and adaptive basis of the system.

  16. Lizard-Skin Surface Texture

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 The south polar region of Mars is covered seasonally with translucent carbon dioxide ice. In the spring gas subliming (evaporating) from the underside of the seasonal layer of ice bursts through weak spots, carrying dust from below with it, to form numerous dust fans aligned in the direction of the prevailing wind. The dust gets trapped in the shallow grooves on the surface, helping to define the small-scale structure of the surface. The surface texture is reminiscent of lizard skin (figure 1). Observation Geometry Image PSP_003730_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 14-May-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 248.5 km (155.3 miles). At this distance the image scale is 24.9 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:04 PM and the scene is illuminated from the west with a solar incidence angle of 69 degrees, thus the sun was about 21 degrees above the horizon. At a solar longitude of 237.5 degrees, the season on Mars is Northern Autumn.

  17. Plasma lipid concentrations for some Brazilian lizards.

    Science.gov (United States)

    Gillett, M P; Lima, V L; Costa, J C; Sibrian, A M

    1979-01-01

    1. Plasma concentrations of cholesterol, cholesteryl esters, phospholipids and triglycerides were determined for ten species of Brazilian lizards, Iguana iguana, Tropidurus torquatos and T. semitaeniatus (Iguanidae), Tupinambis teguixin, Ameiva ameiva and Cnemidophorus ocellifer (Teiidae), Mabuya maculata (Scincidae), Hemidactylus mabouia (Gekkonidae), Amphisbaenia vermicularis and Leposternon polystegum (Amphisbaenidae). 2. Considerable inter- and intra-species variations in plasma lipid concentrations were observed. 3. The percentage of total cholesterol esterified and the individual phospholipid composition of plasma were relatively constant for each species. 4. Over 60% of the cholesteryl esters present in plasma from three species each of iguanid and teiid lizards were polyenoic.

  18. A stem acrodontan lizard in the Cretaceous of Brazil revises early lizard evolution in Gondwana.

    Science.gov (United States)

    Simões, Tiago R; Wilner, Everton; Caldwell, Michael W; Weinschütz, Luiz C; Kellner, Alexander W A

    2015-08-26

    Iguanians are one of the most diverse groups of extant lizards (>1,700 species) with acrodontan iguanians dominating in the Old World, and non-acrodontans in the New World. A new lizard species presented herein is the first acrodontan from South America, indicating acrodontans radiated throughout Gondwana much earlier than previously thought, and that some of the first South American lizards were more closely related to their counterparts in Africa and Asia than to the modern fauna of South America. This suggests both groups of iguanians achieved a worldwide distribution before the final breakup of Pangaea. At some point, non-acrodontans replaced acrodontans and became the only iguanians in the Americas, contrary to what happened on most of the Old World. This discovery also expands the diversity of Cretaceous lizards in South America, which with recent findings, suggests sphenodontians were not the dominant lepidosaurs in that continent as previously hypothesized.

  19. Locomotion patterns in two South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus.

    Science.gov (United States)

    Renous, Sabine; Höfling, Elizabeth; Bels, Vincent

    2008-01-01

    We quantified gait and stride characteristics (velocity, frequency, stride length, stance and swing duration, and duty factor) in the bursts of locomotion of two small, intermittently moving, closely related South American gymnophthalmid lizards: Vanzosaura rubricauda and Procellosaurinus tetradactylus. They occur in different environments: V. rubricauda is widely distributed in open areas with various habitats and substrates, while P. tetradactylus is endemic to dunes in the semi-arid Brazilian Caatinga. Both use trot or walking trot characterised by a lateral sequence. For various substrates in a gradient of roughness (perspex, cardboard, sand, gravel), both species have low relative velocities in comparison with those reported for larger continuously moving lizards. To generate velocity, these animals increase stride frequency but decrease relative stride length. For these parameters, P. tetradactylus showed lower values than V. rubricauda. In their relative range of velocities, no significant differences in stride length and frequency were recorded for gravel. However, the slopes of a correlation between velocity and its components were lower in P. tetradactylus on cardboard, whereas on sand this was only observed for velocity and stride length. The data showed that the difference in rhythmic parameters between both species increased with the smoothness of the substrates. Moreover, P. tetradactylus shows a highly specialised locomotor strategy involving lower stride length and frequency for generating lower velocities than in V. rubricauda. This suggests the evolution of a central motor pattern generator to control slower limb movements and to produce fewer and longer pauses in intermittent locomotion.

  20. Eastern Scheldt Sand, Baskarp Sand No. 15

    DEFF Research Database (Denmark)

    Andersen, A. T; Madsen, E. B.; Schaarup-Jensen, A. L.

    The present data report contains data from 13 drained triaxial tests, performed on two different sand types in the Soil Mechanics Laboratory at Aalborg University in March, 1997. Two tests have been performed on Baskarp Sand No. 15, which has already ken extensively tested in the Soil Mechanics...... Laboratory. The remaining 11 triaxial tests have ben performed on Eastern Scheldt Sand, which is a material not yet investigated at the Soil Mechanics Laboratory. In the first pari of this data report, the characteristics of the two sand types in question will be presented. Next, a description...

  1. VERITAS and multiwavelength observations of the BL Lacertae object 1ES 1741+196

    Science.gov (United States)

    Abeysekara, A. U.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Biteau, J.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Christiansen, J. L.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Huetten, M.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Brien, S.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Pelassa, V.; Petrashyk, A.; Petry, D.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Ratliff, G.; Reyes, L. C.; Reynolds, P. T.; Reynolds, K.; Richards, G. T.; Roache, E.; Rulten, C.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Vincent, S.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

    2016-07-01

    We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy γ-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 ± 0.7stat ± 0.2syst. The integral flux above 180 GeV is (3.9 ± 0.8stat ± 1.0syst) × 10-8 m-2 s-1, corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.

  2. Filling the Infrared Gap: ISO Observations of 1 Jy BL Lacertae Objects

    CERN Document Server

    Padovani, P; Abraham, P; Csizmadia, S; Moor, A

    2006-01-01

    The large majority of BL Lacertae objects belonging to the 1 Jy sample, the class prototype for radio-selected sources, are thought to emit most of their synchrotron power in the far IR band. Ironically, this spectral region is very sparsely sampled, with only a minority of the objects having IRAS data (most of them being upper limits or low-quality detections). We aim at filling this IR gap by presenting new, simultaneous ISOCAM and ISOPHOT observations over the 7 - 200 micron range for half the sample. A measurement of the position of the synchrotron peak frequency, nu_peak, can provide information about particle acceleration mechanisms and constrain the inverse Compton radiation that will be detected by up-coming new gamma-ray missions. We have observed 17 1 Jy BL Lacertae objects with the camera and the photometer on board the Infrared Space Observatory (ISO) satellite. The ISOPHOT data reduction was done employing a novel correction, which mitigates the effect of chopping for faint sources. Using our new...

  3. Parsec-scale jet precession in BL Lacertae (2200+420)

    CERN Document Server

    Caproni, Anderson; Monteiro, Hektor

    2012-01-01

    BL Lacertae is the prototype of the BL Lac class of active galactic nuclei, exhibiting intensive activity on parsec (pc) scales, such as intense core variability and multiple ejections of jet components. In particular, in previous works the existence of precession motions in the pc-scale jet of BL Lacertae has been suggested. In this work we revisit this issue, investigating temporal changes of the observed right ascension and declination offsets of the jet knots in terms of our relativistic jet-precession model. The seven free parameters of our precession model were optimized via a heuristic cross-entropy method, comparing the projected precession helix with the positions of the jet components on the plane of the sky and imposing constraints on their maximum and minimum superluminal velocities. Our optimized best model is compatible with a jet having a bulk velocity of 0.9824c, which is precessing with a period of about 12.1 yr in the observer's reference frame and changing its orientation in relation to the...

  4. VERITAS and Multiwavelength Observations of the BL Lacertae Object 1ES 1741+196

    CERN Document Server

    Abeysekara, A U; Archer, A; Benbow, W; Bird, R; Biteau, J; Buchovecky, M; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Christiansen, J L; Ciupik, L; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Errando, M; Falcone, A; Feng, Q; Finley, J P; Fleischhack, H; Flinders, A; Fortin, P; Fortson, L; Furniss, A; Gillanders, G H; Griffin, S; Grube, J; Gyuk, G; Hütten, M; Hanna, D; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kelley-Hoskins, N; Kertzman, M; Kieda, D; Krause, M; Krennrich, F; Kumar, S; Lang, M J; Maier, G; McArthur, S; McCann, A; Meagher, K; Moriarty, P; Mukherjee, R; Nieto, D; O'Brien, S; de Bhróithe, A O'Faoláin; Ong, R A; Otte, A N; Park, N; Pelassa, V; Petrashyk, A; Pohl, M; Popkow, A; Pueschel, E; Quinn, J; Ragan, K; Ratliff, G; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Rulten, C; Santander, M; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Vincent, S; Wakely, S P; Weiner, O M; Weinstein, A; Wilhelm, A; Williams, D A; Zitzer, B

    2016-01-01

    We present results from multiwavelength observations of the BL Lacertae object 1ES 1741+196, including results in the very-high-energy $\\gamma$-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well-modelled by a power law with a spectral index of $2.7\\pm0.7_{\\mathrm{stat}}\\pm0.2_{\\mathrm{syst}}$. The integral flux above 180 GeV is $(3.9\\pm0.8_{\\mathrm{stat}}\\pm1.0_{\\mathrm{syst}})\\times 10^{-8}$ m$^{-2}$ s$^{-1}$, corresponding to 1.6% of the Crab Nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.

  5. Lizard thermal biology: do genders differ?

    Science.gov (United States)

    Huey, Raymond B; Pianka, Eric R

    2007-09-01

    For more than six decades, physiological ecologists have intensively studied diverse aspects of lizard thermal biology. Nevertheless, a recent review notes that prior studies have generally ignored gender differences in body temperatures, thermal sensitivity, or other aspects of thermal biology. We concur that gender differences have been ignored and should be examined: if gender differences prove common, standard protocols for studying lizard natural history, thermal physiology, and ecology will require significant modification. To help resolve this issue, we conducted a retrospective analysis of our huge data set on the thermal biology of many desert lizards (more than 11,000 individuals from 56 species in seven major clades) from Africa, Australia, and North America. Results are unambiguous: gender differences in body temperature, air temperature, and time of activity--and thus in field thermal biology--are almost always minor. In fact, mean body temperatures of males and females differ by less than 1 degrees C in 80.4% of species. For desert lizards, gender differences in thermal biology are the exception, not the rule. Nevertheless, gender differences should be examined when feasible because exceptions--though likely rare--could be biologically interesting.

  6. Integrative biology of tail autotomy in lizards.

    Science.gov (United States)

    Higham, Timothy E; Russell, Anthony P; Zani, Peter A

    2013-01-01

    Self-amputation (autotomy) of the tail is essential for the survival of many lizards. Accordingly, it has garnered the attention of scientists for more than 200 years. Several factors can influence the release of the tail, such as the size, sex, and age of the lizard; type of predator; ecology; and evolutionary history of the lineage. Once lost, the tail will writhe for seconds to minutes, and these movements likely depend on the size and physiology of the tail, habitat of the lizard, and predation pressure. Loss of the tail will, in turn, have impacts on the lizard, such as modified locomotor performance and mechanics, as well as escape behavior. However, the tail is almost always regenerated, and this involves wound healing, altered investment of resources, and tissue differentiation. The regenerated tail generally differs from the original in several ways, including size, shape, and function. Here we summarize recent findings of research pertaining to tail autotomy, and we propose a framework for future investigations.

  7. Coupled ears in lizards and crocodilians

    DEFF Research Database (Denmark)

    Carr, Catherine E; Christensen-Dalsgaard, Jakob; Bierman, Hilary

    2016-01-01

    Lizard ears are coupled across the pharynx, and are very directional. In consequence all auditory responses should be directional, without a requirement for computation of sound source location. Crocodilian ears are connected through sinuses, and thus less tightly coupled. Coupling may improve...

  8. Lizards of Brazilian Amazonia (Reptilia: Squamata)

    NARCIS (Netherlands)

    Avila-Pires, T.C.S.

    1995-01-01

    Eighty-nine species of lizards, six of which polytypic (forming a total of 97 taxa), are presently known from Brazilian Amazonia. This number includes six species and one subspecies described as new to science in this paper: Stenocercus fimbriatus, Lepidoblepharis hoogmoedi, Leposoma osvaldoi, L. sn

  9. Transaminases activity in the sand lizard’s serum under influence of industrial pollution

    Directory of Open Access Journals (Sweden)

    O. Y. Klymenko

    2009-04-01

    Full Text Available Influence of the environmental pollution on the alanine aminotransferase and aspartate aminotransferase activity in the blood serum of the sand lizard has been studied. Aminotransferases (ALT and AST are similar by the mechanism of action. These enzymes take part in the amino acids metabolism. The increase of the transaminases activities under conditions of the pollution is found. It may be a proof of a damage of relevant organs: namely, the liver.

  10. Transaminases activity in the sand lizard’s serum under influence of industrial pollution

    OpenAIRE

    O. Y. Klymenko; V. Y. Gasso

    2009-01-01

    Influence of the environmental pollution on the alanine aminotransferase and aspartate aminotransferase activity in the blood serum of the sand lizard has been studied. Aminotransferases (ALT and AST) are similar by the mechanism of action. These enzymes take part in the amino acids metabolism. The increase of the transaminases activities under conditions of the pollution is found. It may be a proof of a damage of relevant organs: namely, the liver.

  11. Influence green sand system by core sand additions

    OpenAIRE

    N. Špirutová; J. Beňo; V. Bednářová; J. Kříž; M. Kandrnál

    2012-01-01

    Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron) are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this co...

  12. Baskarp Sand No. 15

    DEFF Research Database (Denmark)

    Borup, Marianne; Hedegaard, Jette

    The Soil Mechanics Laboratory has started performing tests with a new sand, Baskarp No 15. Baskarp No 15 is a graded sand from Sweden. The shapes of the largest grains are round, while the small grains have sharp edges. The main part of of Baskarp No 15 is quarts, but it also contains feldspar...... and biotit. Mainly the sand will be used for tests concerning the development og the theory of building up pore pressure in sand, L. B. Ibsen 1993....

  13. Lund Sand No 0

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Jakobsen, Finn Rosendal

    During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve...

  14. Habitat degradation may affect niche segregation patterns in lizards

    Science.gov (United States)

    Pelegrin, N.; Chani, J. M.; Echevarria, A. L.; Bucher, E. H.

    2013-08-01

    Lizards partition resources in three main niche dimensions: time, space and food. Activity time and microhabitat use are strongly influenced by thermal environment, and may differ between species according to thermal requirements and tolerance. As thermal characteristics are influenced by habitat structure, microhabitat use and activity of lizards can change in disturbed habitats. We compared activity and microhabitat use of two abundant lizard species of the Semi-arid Chaco of Argentina between a restored and a highly degraded Chaco forest, to determine how habitat degradation affects lizard segregation in time and space, hypothesizing that as activity and microhabitat use of lizards are related to habitat structure, activity and microhabitat use of individual species can be altered in degraded habitats, thus changing segregation patterns between them. Activity changed from an overlapped pattern in a restored forest to a segregated pattern in a degraded forest. A similar trend was observed for microhabitat use, although to a less extent. No correlation was found between air temperature and lizard activity, but lizard activity varied along the day and among sites. Contrary to what was believed, activity patterns of neotropical diurnal lizards are not fixed, but affected by multiple factors related to habitat structure and possibly to interspecific interactions. Changes in activity patterns and microhabitat use in degraded forests may have important implications when analyzing the effects of climate change on lizard species, due to synergistic effects.

  15. BL Lacertae objects and radio-loud quasars within an evolutionary unified scheme

    Energy Technology Data Exchange (ETDEWEB)

    Vagnetti, F.; Cavaliere, A.; Giallongo, E. (Roma II Universita, Rome (Italy) Roma Osservatorio Astronomico, Rome (Italy))

    1991-02-01

    On the basis of a joint radio-optical analysis, different amounts of cosmological luminosity evolution in the optical band for flat- and steep-spectrum radio-loud quasars are found. Specifically, a slower evolution for the flat-spectrum quasars, evidence of a sluggish beamed component in the optical band additional to the canonical isotropic continuum is shown. The persistence of the beamed component in terms of a spectral evolution with the Doppler factor increasing somewhat in cosmic time is interpreted. The BL Lacertae objects are placed into this framework and an evolutionary unified scheme is proposed maintaining spectral and statistical continuity of BL Lacs with flat-spectrum quasars. Supportive observational evidence, and clues for the parent population, are discussed. 57 refs.

  16. Broad-Band Spectral Indices Variability of BL Lacertae by Wavelet Method

    Indian Academy of Sciences (India)

    Hao-Jing Zhang; Jing-Ming Bai; Yu-Ying Bao; Xiong Zhang

    2014-09-01

    BL Lacertae is one of the famous AGN that shows convincing evidence to support periodic variability. We compile R-band data and radio 22 GHz database from the available literature to build the light curves and to calculate broad-band spectral indices. This paper employs the wavelet periodic estimation method. The analysis results indicate that the most possible period is 7.02–7.36 yr in the selected wave-bands. The broad-band spectral indices have a possible period of 4.11 yr as a half value in selected wave-bands. The results confirm that the variability period in the radio 22 GHz is in agreement with the optical R band of about 7.01 yr, as also mentioned in other literatures.

  17. Optical polarimetry of PKS 2155 - 304 and constraints on accretion disk models for BL Lacertae objects

    Science.gov (United States)

    Smith, Paul S.; Sitko, Michael L.

    1991-01-01

    Optical broad-band polarimetry and photometry of the BL Lacertae object PKS 2155 - 304 during late 1990 are presented. Variability in both flux and linear polarization was moderate during this period. The optical polarization ranged from 2 to 7 percent while photometric variations were within 0.2 mag (V = 13.2-13.4). Accurate multicolor measurements were made to study any wavelength dependence of the polarization with an eye to using these data to test the model of Wandel and Urry (1991) which proposes that the UV to soft X-ray continuum of this object arises from an accretion disk. Wavelength-dependent polarization (WDP) is observed in PKS 2155 - 304. However, the polarization is always seen to decrease with wavelength when WDP is observed. This is opposite to the expected sense of WDP if the UV continuum is dominated by an accretion disk.

  18. The Binary Black Hole Scenario for the BL Lacertae Object AO 0235+16

    Institute of Scientific and Technical Information of China (English)

    G. E. Romero; Jun-Hui Fan; S. E. Nuza

    2003-01-01

    Recent analysis of the long term radio light curve of the extremely variable BL Lacertae object AO 0235t16 by Raiteri et al. have revealed the presence of recurrent outbursts with a period of ~ 5.7 ± 0.5yr. Periodicity analysis of the optical light curve also shows evidence for a shorter period. Here we discuss whether such a behavior can be explained by a binary black hole model where the accretion disk of one of the supermassive black holes is precessing due to the tidal effects of the companion. We estimate the mass of the accreting hole and analyze constraints on the secondary mass and the orbital parameters of the system. It is possible to provide a viable interpretation of the available multiwavelength data.

  19. Short Timescale Photometric and Polarimetric Behavior of two BL Lacertae Type Objects

    CERN Document Server

    Covino, S; Foschini, L; Sandrinelli, A; Tavecchio, F; Treves, A; Zhang, H; de Almeida, U Barres; Bonnoli, G; Boettcher, M; Cecconi, M; D'Ammando, F; di Fabrizio, L; Giarrusso, M; Leone, F; Lindfors, E; Lorenzi, V; Molinari, E; Paiano, S; Prandini, E; Raiteri, C M; Stamerra, A; Tagliaferri, G

    2015-01-01

    Blazars are astrophysical sources whose emission is dominated by non-thermal processes, typically interpreted as synchrotron and inverse Compton emission. Although the general picture is rather robust and consistent with observations, many aspects are still unexplored. Polarimetric monitoring can offer a wealth of information about the physical processes in blazars. Models with largely different physical ingredients can often provide almost indistinguishable predictions for the total flux, but usually are characterized by markedly different polarization properties. We explore, with a pilot study, the possibility to derive structural information about the emitting regions of blazars by means of a joint analysis of rapid variability of the total and polarized flux at optical wavelengths. Short timescale (from tens of seconds to a couple of minutes) optical linear polarimetry and photometry for two blazars, BL Lacertae and PKS 1424+240, was carried out with the PAOLO polarimeter at the 3.6m Telescopio Nazionale ...

  20. Coupled, Active Oscillators and Lizard Otoacoustic Emissions

    Science.gov (United States)

    Bergevin, Christopher; Velenovsky, David S.; Bonine, Kevin E.

    2011-11-01

    The present study empirically explores the relationship between spontaneous otoacoustic emissions (SOAEs) and stimulus-frequency emissions (SFOAEs) in lizards, an ideal group for such research given their relatively simple inner ear (e.g., lack of basilar membrane traveling waves), diverse morphology across species/families (e.g., tectorial membrane structure) and robust emissions. In a nutshell, our results indicate that SFOAEs evoked using low-level tones are intimately related to underlying SOAE activity, and appear to represent the entrained response of active oscillators closely tuned to the probe frequency. The data described here indicate several essential features that are desirable to capture in theoretical models for auditory transduction in lizards, and potentially represent generic properties at work in many different classes of "active" ears.

  1. RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

    Energy Technology Data Exchange (ETDEWEB)

    Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T.; Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W.; Feng, Q.; Finley, J. P. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J.; Fortson, L. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Federici, S. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Finnegan, G., E-mail: qfeng@purdue.edu, E-mail: cui@purdue.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Collaboration: VERITAS Collaboration; and others

    2013-01-10

    We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6 minute exposure, when the integral flux above 200 GeV reached (3.4 {+-} 0.6) Multiplication-Sign 10{sup -6} photons m{sup -2} s{sup -1}, roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be 13 {+-} 4 minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of 3.6 {+-} 0.4, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. Contemporaneous radio observations of the source with the Very Long Baseline Array revealed the emergence of a new, superluminal component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results.

  2. Eocene lizard from Germany reveals amphisbaenian origins.

    Science.gov (United States)

    Müller, Johannes; Hipsley, Christy A; Head, Jason J; Kardjilov, Nikolay; Hilger, André; Wuttke, Michael; Reisz, Robert R

    2011-05-19

    Amphisbaenia is a speciose clade of fossorial lizards characterized by a snake-like body and a strongly reinforced skull adapted for head-first burrowing. The evolutionary origins of amphisbaenians are controversial, with molecular data uniting them with lacertids, a clade of Old World terrestrial lizards, whereas morphology supports a grouping with snakes and other limbless squamates. Reports of fossil stem amphisbaenians have been falsified, and no fossils have previously tested these competing phylogenetic hypotheses or shed light on ancestral amphisbaenian ecology. Here we report the discovery of a new lacertid-like lizard from the Eocene Messel locality of Germany that provides the first morphological evidence for lacertid-amphisbaenian monophyly on the basis of a reinforced, akinetic skull roof and braincase, supporting the view that body elongation and limblessness in amphisbaenians and snakes evolved independently. Morphometric analysis of body shape and ecology in squamates indicates that the postcranial anatomy of the new taxon is most consistent with opportunistically burrowing habits, which in combination with cranial reinforcement indicates that head-first burrowing evolved before body elongation and may have been a crucial first step in the evolution of amphisbaenian fossoriality.

  3. Growth and activity of Sceloporus cowlesi (southwestern fence lizard)

    Science.gov (United States)

    Heather L. Bateman; Alice Chung-MacCoubrey

    2012-01-01

    Lizards from the Sceloporus undulatus complex have been the subject of many studies on lizard ecology (Hager 2001; Rosenblum 2006; Rosenblum et al. 2007), behavior (Hein and Whitaker 1997; Robertson and Rosenblum 2009), and reproduction (Vinegar 1975; Robertson and Rosenblum 2010). However, genetic data (Leache and Reeder 2002) support reallocation of the subspecies of...

  4. Influence green sand system by core sand additions

    Directory of Open Access Journals (Sweden)

    N. Špirutová

    2012-01-01

    Full Text Available Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: “How the green sand systems are influenced by core sands?”This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50 %. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition. Ratio of active betonite by Methylene blue test was also determined.

  5. Perch-height specific predation on tropical lizard clay models: implications for habitat selection in mainland neotropical lizards.

    Science.gov (United States)

    Steffen, John E

    2009-09-01

    Predation has been hypothesized to be a strong selective force structuring communities of tropical lizards. Comparisons of perch height and size-based predation frequencies can provide a unique window into understanding how predation might shape habitat selection and morphological patterns in lizards, especially anoles. Here I use plasticine clay models, placed on the trunks of trees and suspended in the canopy to show that predation frequency on clay models differs primarily according to habitat (canopy vs. trunk-ground), but not according to size. These data are discussed in light of observed lizard abundances in the lowland forests of Costa Rica, and are presented as partial explanation for why fewer lizards are found in tree canopies, and more lizards are found on ground-trunk habitats.

  6. Interhabitat differences in energy acquisition and expenditure in a lizard

    Energy Technology Data Exchange (ETDEWEB)

    Karasov, W.H.; Anderson, R.A.

    1984-02-01

    Cnemidophorus hyperythrus, a small (approx. =4-g) teiid lizard, occurs along an elevational thorn scrub-thorn woodland-thorn forest habitat gradient in the cape region of Baja California. The authors compared body size, daily energy expenditure (DEE, measured with double labeled water), relative feeding rate (as reflected by H/sub 2/O influx rate), behavior, and abundance of this species at two sites along the gradient. At the inland thorn woodland site C. hyperythrus were more abundant (approx. =50 lizards/ha.). Mean body mass of woodland site lizards was 13% greater than that of scrub lizards. The DEE of the thorn woodland lizards, 330 site J x g/sup -1/ x d/sup -1/, and their H/sub 2/O influx, 99 mm/sup 3/ x g/sup -1/ x d/sup -1/, were also higher than the thorn scrub lizards', 219 J x g/sup -1/ x d/sup -1/ and 52 mm/sup 3/ x g/sup -1/ x d/sup -1/. Diets at the two sites were similar. There were no differences between sexes in diet, DEE, or H/sub 2/ influx. Daily maintenance energy costs were calculated based upon laboratory measures of O/sub 2/ consumption of resting lizards at a series of temperatures that represented the daily range of body temperatures experienced by lizards in the field. Activity costs (=DEE minus maintenance) were three times higher in the woodland lizards. Behavioral observations showed that woodland lizards were active most of the day (approx. =9 h/d) whereas scrub lizards were active primarily in the morning (approx. =3.5 h/d). Thus, the higher activity cost, DEE, and feeding rate of woodland lizards can be explained by their longer daily activity period. We suggest causal factors for the difference in daily activity period, and discuss implications of length of daily forging period for adult body size, population density, and various life history parameters of lizards.

  7. Sands cykliske styrke

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    1992-01-01

    Sands cykliske styrke kan beskrives ved Cyclic Liquefaction, Mobilisering, Stabilization og Instant Stabilization. I artiklen beskrives hvorfor Stabilization og Instant Stabilization ikke observeres, når sands udrænede styrke undersøges i triaxial celler, der anvender prøver med dobbelt prøvehøjde....

  8. Baskarp Sand No. 15

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Bødker, Lars Bødker

    The Soil Mechanics Laboratory has started performing tests with a new sand, Baskarp No 15. Baskarp No 15 is a graded sand from Sweden. The shapes of the largest grains are round, while the small grains have sharp edges. The main part of of Baskarp No 15 is quarts, but it also contains feldspar...

  9. GABAergic cell types in the lizard hippocampus.

    Science.gov (United States)

    Guirado, S; Dávila, J C

    1999-04-01

    The neurochemical classification of GABAergic cells in the lizard hippocampus resulted in a further division into four major, non-overlapping subtypes. Each GABAergic cell subtype displays specific targets on the principal hippocampal neurons. The synaptic targets of the GABA/neuropeptide subtype are the distal apical dendrites of principal neurons. Calretinin- and parvalbumin-containing GABAergic cells synapse on the cell body and proximal dendrites of principal cells. Calbindin is expressed in a distinct group of interneurons, the synapses of which are directed to the dendrites of principal neurons. Finally, another subtype displays NADPH-diaphorase activity, but its synaptic target has not been established.

  10. The Lizard Wireless Station of Guglielmo Marconi

    Science.gov (United States)

    Montstein, Christian

    2014-08-01

    During the vacation with my wife in Cornwall, we by chance were walking by the Lizard wireless station, originally installed by Guglielmo Marconi and recently refurbished by The National Trust/UK. Fortunately the shed was open for public visitors and a student was present telling stories about the station and its history. The historic equipment was demonstrated by sending some Morse codes. The high voltage sparks and its sound were quite impressive while in the background the Morse code receiver punched dots and dashes onto the strip chart.

  11. Prevalence of neutralising antibodies against adenoviruses in lizards and snakes.

    Science.gov (United States)

    Ball, Inna; Ofner, Sabine; Funk, Richard S; Griffin, Chris; Riedel, Ulf; Möhring, Jens; Marschang, Rachel E

    2014-10-01

    Adenoviruses (AdVs) are relatively common in lizards and snakes, and several genetically distinct AdVs have been isolated in cell culture. The aims of this study were to examine serological relationships among lizard and snake AdVs and to determine the frequency of AdV infections in these species. Isolates from a boa constrictor (Boa constrictor), a corn snake (Pantherophis gutattus) and a central bearded dragon (Pogona vitticeps), and two isolates from helodermatid lizards (Heloderma horridum and H. suspectum) were used in neutralisation tests for the detection of antibodies in plasma from 263 lizards from seven families (including 12 species) and from 141 snakes from four families (including 28 species) from the USA and Europe. Most lizard and snake samples had antibodies against a range of AdV isolates, indicating that AdV infection is common among these squamates. Neutralisation tests with polyclonal antibodies raised in rabbits demonstrated serological cross-reactivity between both helodermatid lizard isolates. However, squamate plasma showed different reactions to each of these lizard isolates in neutralisation tests.

  12. Nephtyidae (Annelida: Phyllodocida) of Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Murray, Anna; Wong, Eunice; Hutchings, Pat

    2015-09-18

    Seven species of the family Nephtyidae are recorded from Lizard Island, none previously reported from the Great Barrier Reef. Two species of Aglaophamus, four species of Micronephthys, one new and one previously unreported from Australia, and one species of Nephtys, were identified from samples collected during the Lizard Island Polychaete Workshop 2013, as well as from ecological studies undertaken during the 1970s and deposited in the Australian Museum marine invertebrate Collections. A dichotomous key to aid identification of these species newly reported from Lizard Island is provided.

  13. Limb development in the gekkonid lizard Gonatodes albogularis: A reconsideration of homology in the lizard carpus and tarsus.

    Science.gov (United States)

    Leal, Francisca; Tarazona, Oscar A; Ramírez-Pinilla, Martha Patricia

    2010-11-01

    Despite the attention squamate lizards have received in the study of digit and limb loss, little is known about limb morphogenesis in pentadactyl lizards. Recent developmental studies have provided a basis for understanding lizard autopodial element homology based on developmental and comparative anatomy. In addition, the composition and identity of some carpal and tarsal elements of lizard limbs, and reptiles in general, have been the theme of discussions about their homology compared to non-squamate Lepidosauromorpha and basal Amniota. The study of additional embryonic material from different lizard families may improve our understanding of squamate limb evolution. Here, we analyze limb morphogenesis in the gekkonid lizard Gonatodes albogularis describing patterns of chondrogenesis and ossification from early stages of embryonic development to hatchlings. Our results are in general agreement with previous developmental studies, but we also show that limb development in squamates probably involves more chondrogenic elements for carpal and tarsal morphogenesis, as previously recognized on the grounds of comparative anatomy. We provide evidence for the transitory presence of distal carpale 1 and intermedium in the carpus and tibiale, intermedium, distal centralia, and distal tarsale 2 in the tarsus. Hence, we demonstrate that some elements that were believed to be lost in squamate evolution are conserved as transitory elements during limb development. However, these elements do not represent just phylogenetic burden but may be important for the morphogenesis of the lizard autopodium.

  14. Quantum Probabilistic Structures in Competing Lizard Communities

    CERN Document Server

    Aerts, Diederik; Kuna, Maciej; Sinervo, Barry; Sozzo, Sandro

    2012-01-01

    Almost two decades of research on the use of the mathematical formalism of quantum theory as a modeling tool for entities and their dynamics in domains different from the micro-world has now firmly shown the systematic appearance of quantum structures in aspects of human behavior and thought, such as in cognitive processes of decision-making, and in the way concepts are combined into sentences. In this paper, we extend this insight to animal behavior showing that a quantum probabilistic structure models the mating competition of three side-blotched lizard morphs. We analyze a set of experimental data collected from 1990 to 2011 on these morphs, whose territorial behavior follows a cyclic rock-paper-scissors (RPS) dynamics. Consequently we prove that a single classical Kolmogorovian space does not exist for the lizard's dynamics, and elaborate an explicit quantum description in Hilbert space faithfully modeling the gathered data. This result is relevant for population dynamics as a whole, since many systems, e...

  15. Fanaroff-Riley I galaxies as the parent population of BL Lacertae objects. II - Optical constraints

    Energy Technology Data Exchange (ETDEWEB)

    Padovani, P.; Urry, C.M. (Space Telescope Science Institute, Baltimore, MD (USA))

    1991-02-01

    The hypothesis is investigated that BL Lacertae objects are a subset of Fanaroff-Riley (FR) I galaxies dominated by beamed emission from a relativistic jet aligned with the line of sight. It is found that FR I galaxies, although of low radio luminosity, are bright optical galaxies. If the beaming hypothesis is correct, the optical luminosity function of BL Lac objects, including the effect of the host galaxy, can be approximated by a double power law with a given differential index. New estimates of the number counts of BL Lac objects are made which constrain their local number density for L(B) greater than about 6 x 10 to the 43rd ergs/s to be in the range 110-720/cu Gpc. The corresponding ratio between the total number densities of BL Lac objects and FR I galaxies is 0.003 to 0.02. This limits the Lorentz factor of the optical emission to the range 8-20, larger than that of the X-ray emitting plasma and roughly of the same order as the radio Lorentz factor. 34 refs.

  16. Analysis of the activity of the blazar BL Lacertae over the period 1998-2011

    Science.gov (United States)

    Strigunov, K. S.; Zhovtan, A. V.

    2016-07-01

    In 1998-2011 the blazar (active galactic nucleus) BL Lacertae was observed at Crimean Astrophysical Observatory (CrAO) with the second-generation GT-48 Cherenkov telescope at energies >1 TeV with a total significance of 11.8σ. More than 20 flares and a fourfold change in yearly mean fluxes (>1 TeV) were recorded. The optical ( B band) data obtained at CrAO and the TeV data are shown to correlate in some time intervals. The optical data are also compared with the X-ray RXTE/ASM (2-10 keV) data. In addition, the data from GT-48 are compared with the gamma-ray fluxes recorded by the Fermi LAT space telescope (0.1-300 GeV). The 2009 flare at TeV and Fermi energies has been studied. As a result, it has been found that as the activity rises the increase in flux at high energies exceeds its increase at low energies. This conclusion may be related to the conversion mechanism of particle acceleration. This is consistent with the results of studies for a similar object, 1ES 1426+428.

  17. Constraints on the Very High Energy Emission from BL Lacertae Objects

    CERN Document Server

    Horan, D; Bond, I H; Boyle, P J; Bradbury, S M; Buckley, J H; Carter-Lewis, A; Catanese, M; Celik, O; Cui, W; Daniel, M; D'Vali, M; dela Calle, I; Perez; Duke, C; Falcone, A; Fegan, D J; Fegan, S J; Finley, J P; Fortson, L F; Gaidos, A; Gammell, S; Gibbs, K; Gillanders, G H; Grube, J; Hall, J; Hall, T A; Hanna, D; Hillas, A M; Holder, J; Jarvis, A; Jordan, M; Kenny, G E; Kertzman, M; Kieda, D; Kildea, J; Knapp, J; Kosack, K; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Linton, E T; Lloyd-Evans, J; Milovanovic, A; Moriarty, P; Müller, D; Nagai, T; Nolan, S J; Ong, R A; Pallassini, R; Petry, D; Power-Mooney, B; Quinn, J; Quinn, M; Ragan, K; Rebillot, P; Reynolds, P T; Rose, J H; Schroedter, M; Sembroski, G H; Swordy, S P; Syson, A; Vasilev, V V; Wakely, S P; Walker, G; Weekes, T C; Zweerink, J

    2003-01-01

    We present results from observations of 29 BL Lacertae objects, taken with the Whipple Observatory 10 m Gamma-Ray Telescope between 1995 and 2000. The observed objects are mostly at low redshift (z < 0.2) but observations of objects of z up to 0.444 are also reported. Five of the objects are EGRET sources and two are unconfirmed TeV sources. Three of the confirmed sources of extragalactic TeV gamma rays were originally observed as part of this survey and have been reported elsewhere. No significant excesses are detected from any of the other objects observed, on time scales of days, months or years. We report 99.9% confidence level flux upper limits for the objects for each observing season. The flux upper limits are typically 20% of the Crab flux although, for some sources, limits as sensitive as 6% of the Crab flux were derived. The results are consistent with the synchrotron-self-Compton (SSC) model predictions considered in this work.

  18. The awakening of BL Lacertae: observations by Fermi, Swift, and the GASP-WEBT

    CERN Document Server

    Raiteri, C M; D'Ammando, F; Larionov, V M; Gurwell, M A; Mirzaqulov, D O; Smith, P S

    2013-01-01

    Since the launch of the Fermi satellite, BL Lacertae has been moderately active at gamma-rays and optical frequencies until May 2011, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily gamma-ray observations by Fermi. Discrete correlation analysis between the optical and gamma-ray emission reveals correlation with a time lag of 0 +- 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time scales than corresponding gamma-ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiat...

  19. Effects of Redshift on the Classifying Criteria of BL Lacertae Objects

    Institute of Scientific and Technical Information of China (English)

    Li Ma; Luo-En Chen; Guang-Zhong Xie; Ji-Yang Ren; Zhao-Hua Xie; Shu-Bai Zhou; Hui Wu; Dong-Cheng Mei

    2007-01-01

    We have collected a sample of 70 BL Lacs(33 radio-selected BL Lacs and 37 X-ray selected BL Lacs) with multi-waveband data for investigating the classifying criteria of BL Lacertae Objects.For each source,we estimate its luminosities in radio.optical and X-ray,the broad-band spectral index from radio to X-ray and the peak frequency of the synchrotron emission,and make a statistical analysis of the data obtained.Our main results are as follows:(1)The broad-band spectral index and the peak frequency have no correlation with the redshift.while they are inversely correlated with each other and they could be regarded as equivalent classifying criteria of BL Lac objects.(2)There are significant effects of the luminosity/redshift relation on the observed luminosity distribution in our sample,hence,if the radio luminosity is to be used as a classifying criterion of BL Lac objects.it should not be regarded as equivalent to the broad-band spectral index or the peak frequency.(3)Our results supply a specific piece of evidence for the suggestion that the use of luminosities always introduces a redshift bias to the data and show that the location of the peak frequency is not always linked to the luminosity of any wave band.

  20. Six-year Optical Monitoring of BL Lacertae Object 1ES 0806+52.4

    CERN Document Server

    Man, Zhongyi; Wu, Jianghua; Zhou, Xu; Yuan, Qirong

    2014-01-01

    We present the results of the first systematic long-term multi-color optical monitoring of the BL Lacertae object 1ES 0806+52.4. The monitoring was performed in multiple passbands with a 60/90 cm Schmidt telescope from December 2005 to February 2011. The overall brightness of this object decreased from 2005 December to 2008 December, and regained after that. A sharp outburst probably occurred around the end of our monitoring program. Overlapped on the long-term trend are some short-term small-amplitude oscillations. No intra-night variability was found in the object, which is in accord with the historical observations before 2005. By investigating the color behavior, we found strong bluer-when-brighter chromatism for the long-term variability of 1ES 0806+52.4. The total amplitudes at the c, i and o bands are 1.18, 1.12, and 1.02 mags, respectively. The amplitudes tend to increase toward shorter wavelength, which may be the major cause of bluer-when-brighter. Such bluer-when-brighter is also found in other bla...

  1. Simultaneous optical monitoring of BL Lacertae object S5 0716+714 with high temporal resolution

    Science.gov (United States)

    Man, Zhongyi; Zhang, Xiaoyuan; Wu, Jianghua; Yuan, Qirong

    2016-03-01

    We have monitored the BL Lacertae object S5 0716+714 simultaneously in the B, R and I bands on three nights in 2014 November. The average time resolution is quite high (73, 34 and 58 s for the filters B, R and I), which can help us trace the profile of the variation and search for the short inter-band time delay. Intra-day variability was about 0.1 mag on the first two nights and more than 0.3 mag on the third. A bluer-when-brighter colour behaviour was found. A clear loop path can be seen on the colour-magnitude diagram of the third night, revealing possible time delays between variations at high and low energies. It is the first time that the intra-day spectral hysteresis loop has been found so obviously in the optical band. We used the interpolated cross-correlation function method to further confirm the time delay and calculated the values of lag between light curves at different wavelengths on each night. On the third night, variations in the R and B bands are approximately 1.5 min lagging behind the I band. Such optical time delay is probably due to the interplay of different processes of electrons in the jet of the blazar.

  2. Simultaneous optical monitoring of BL Lacertae object S5 0716+714 with high temporal resolution

    CERN Document Server

    Man, Zhongyi; Wu, Jianghua; Yuan, Qirong

    2015-01-01

    We have monitored the BL Lacertae object S5 0716+714 simultaneously in the B, R and I bands on three nights in November 2014. The average time resolution is quite high (73s, 34s, 58s for the filters B, R and I), which can help us trace the profile of the variation and search for the short inter-band time delay. Intra-day variability was about 0.1 mag on the first two nights and more than 0.3 mag on the third. A bluer-when-brighter color behavior was found. An clear loop path can be seen on the color-magnitude diagram of the third night, revealing possible time delays between variations at high and low energies. It is the first time that the intra-day spectral hysteresis loop has been found so obviously in the optical band. We used the interpolated cross-correlation function method to further confirm the time delay and calculated the values of lag between light curves at different wavelengths on each night. On the third night, variations in the R and B bands is approximately 1.5 minutes lagging behind the I ba...

  3. The HST Survey of BL~Lacertae Objects. IV. Infrared Imaging of Host Galaxies

    CERN Document Server

    Scarpa, R; Padovani, P; O'Dowd, M; Scarpa, Riccardo; Padovani, Paolo; O'Dowd, Matthew; Calzetti, Daniela

    2000-01-01

    The HST NICMOS Camera 2 was used for H-band imaging of 12 BL Lacertae objects taken from the larger sample observed with the WFPC2 in the R band (Urry et al. 2000; Scarpa et al. 2000). Ten of the 12 BL Lacs are clearly resolved, and the detected host galaxies are large, bright ellipticals with average H-band absolute magnitude M=-26.2+-0.45 mag and effective radius 10+-5 kpc. The rest-frame integrated color of the host galaxies is on average R-H=2.3+-0.3, consistent with the value for both radio galaxies and normal, non-active elliptical galaxies, and indicating the dominant stellar population is old. The host galaxies tend to be bluer in their outer regions than in their cores, with average color gradient Delta(R-H)/Delta(log r)=-0.2 mag, again consistent with results for normal non-active elliptical galaxies. The infrared Kormendy relation, derived for the first time for BL Lac host galaxies, is m(e) = 3.8*log(R)+14.8 (where m(e) is the surface brightness at the effective radius R), fully in agreement with ...

  4. The Hubble Space Telescope Survey of BL Lacertae Objects. IV. Infrared Imaging of Host Galaxies

    Science.gov (United States)

    Scarpa, Riccardo; Urry, C. Megan; Padovani, Paolo; Calzetti, Daniela; O'Dowd, Matthew

    2000-11-01

    The Hubble Space Telescope NICMOS Camera 2 was used for H-band imaging of 12 BL Lacertae objects taken from the larger sample observed with the WFPC2 in the R band by Urry and coworkers and Scarpa and coworkers. Ten of the 12 BL Lacs are clearly resolved, and the detected host galaxies are large, bright ellipticals with average absolute magnitude =-26.2+/-0.45 mag and effective radius =10+/-5 kpc. The rest-frame integrated color of the host galaxies is on average =2.3+/-0.3, consistent with the value for both radio galaxies and normal, nonactive elliptical galaxies and indicating that the dominant stellar population is old. The host galaxies tend to be bluer in their outer regions than in their cores, with average color gradient Δ(R-H)/Δlogr=-0.2 mag, again consistent with results for normal nonactive elliptical galaxies. The infrared Kormendy relation, derived for the first time for BL Lac host galaxies, is μe=3.8logre+14.8, fully in agreement with the relation for normal ellipticals. The close similarity between BL Lac host galaxies and normal ellipticals suggests that the active nucleus has surprisingly little effect on the host galaxy. This supports a picture in which all elliptical galaxies harbor black holes that can be actively accreting for some fraction of their lifetime.

  5. Optical and UV spectroscopy of the peculiar RS CVn system, RT Lacertae

    Science.gov (United States)

    Huenemoerder, D. P.; Barden, S. C.

    1985-01-01

    Spectra in the H-alpha and H-beta regions of the peculiar double-lined RS CVn binary, RT Lacertae, were obtained in the fall of 1984. Limited International Ultraviolet Explorer (IUE) long wavelength low and high resolution spectra were obtained concurrently. The ground based spectra have shown an asymmetry with orbital phase in the H-alpha profile. The H-beta profiles were consistent with the same effect. One hemisphere showed excess emission and the other excess absorption, with a broad Gaussian emission component superposed upon the excess H-alpha line. An improved radial velocity curve, giving a better determined mass ratio and geometry was derived. This combined with the radii implied by the rotational broadening of the spectra, showed one component to be 80 to 90% filling the equilibrium Roche surface. The two-faced nature is, therfore, very likely due to mass transfer from the contact component impacting upon its companion. Low resolution ultraviolet data showed that the supposed cooler component is bluer than its companion. High resolution ultraviolet data taken during secondary eclipse showed Mg II emission strength which decreased more slowly than the area visible. The phase behavior of the low resolution data support the former situation, indicating traditional chromospheric activity.

  6. Rapid Synchrotron Flares from BL Lacertae Detected by ASCA and RXTE

    CERN Document Server

    Tanihata, C; Kataoka, J; Madejski, G M; Inoue, S; Kubo, H; Makino, F; Mattox, J R; Kawai, N

    2000-01-01

    We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray, optical, and gamma-ray emission, with its 2-10 keV flux peaking at ~3.3 E-11 erg/cm2/s. This is more than 3 times higher than the value measured by ASCA in 1995. We detected two rapid flares which occured only in the soft X-ray band, while the hard X-ray flux also increased, but decayed with a much longer time scale. Together with the requirement of a very steep and varying power law dominating the soft X-ray band in addition to the hard power law, we suggest that both the high energy end of the synchrotron spectrum and the hard inverse Compton spectrum were visible in this source during the outburst. We discuss the possible origins of the observed variability time scales, and interpret the short time scales of the soft X-ray variability as reflecting the size of the emission regi...

  7. Sand and Gravel Deposits

    Data.gov (United States)

    Vermont Center for Geographic Information — This dataset is a statewide polygon coverage of sand, gravel, and stone resources. This database includes the best data available from the VT Agency of Natural...

  8. Sand and Gravel Operations

    Data.gov (United States)

    Department of Homeland Security — This map layer includes sand and gravel operations in the United States. These data were obtained from information reported voluntarily to the USGS by the aggregate...

  9. Vestled - Hvide Sande

    DEFF Research Database (Denmark)

    Juel-Christiansen, Carsten; Hesselbjerg, Marianne; Schønherr, Torben

    2009-01-01

    Værket Vestled i Hvide Sande præsenteret i sammenhæng af 1000 nutidige landskabsarkitektoniske arbejder fra hele verden, hvor hvert værk vises på én side......Værket Vestled i Hvide Sande præsenteret i sammenhæng af 1000 nutidige landskabsarkitektoniske arbejder fra hele verden, hvor hvert værk vises på én side...

  10. Status of the Island Night Lizard and Two Non-Native Lizards on Outlying Landing Field San Nicolas Island, California

    Science.gov (United States)

    Fellers, Gary M.; Drost, Charles A.; Murphey, Thomas G.

    2008-01-01

    More than 900 individually marked island night lizards (Xantusia riversiana) were captured on San Nicolas Island, California, between 1984 and 2007 as part of an ongoing study to monitor the status of this threatened species. Our data suggest that at least a few lizards are probably more than 20 years old, and one lizard would be 31.5 years old if it grew at an average rate for the population. Ages of 20 and 30 years seem reasonable given the remarkably slow growth during capture intervals of more than a decade for five of the lizards which we estimated to be 20 or more years old. Like other lizards, island night lizard growth rates vary by size, with larger lizards growing more slowly. In general, growth rates were somewhat greater on San Nicolas Island (compared with Santa Barbara Island), and this increase was sustained through all of the intermediate size classes. The higher growth rate may account for the somewhat larger lizards present on San Nicolas Island, although we cannot discount the possibility that night lizards on San Nicolas are merely living longer. The high percentage of small lizards in the Eucalyptus habitat might seem to reflect a healthy population in that habitat, but the high proportion of small lizards appears to be caused by good reproduction in the 1900s and substantially poorer reproduction in subsequent years. The Eucalyptus habitat has dried quite a bit in recent years. Night lizards in the Haplopappus/Grassland habitat have shown an increase in the proportion of larger lizards since 2000. There has also been an increase in the proportion of large lizards in the Rock Cobble habitat at Redeye Beach. However, there are has been some change in habitat with more elephant seals occupying the same area just above the high tide as do the night lizards. Southern alligator lizards and side-blotched lizards are both non-native on San Nicolas Island. Neither lizard causes obvious harm to island night lizards, and management time and effort should

  11. MECHANICAL REGENERATION OF SAND WASTE

    Directory of Open Access Journals (Sweden)

    D. I. Gnir

    2005-01-01

    Full Text Available The experimental activation of the sand regenerator of the firm SINTO is carried out at ОАО “MZOO". It is shown that sand grains are cleared from films of binding agents, that allows to use the treated sand for preparation of agglutinant and core sands.

  12. A New Eocene Casquehead Lizard (Reptilia, Corytophanidae) from North America.

    Science.gov (United States)

    Conrad, Jack L

    2015-01-01

    A new fossil showing affinities with extant Laemanctus offers the first clear evidence for a casquehead lizard (Corytophanidae) from the Eocene of North America. Along with Geiseltaliellus from roughly coeval rocks in central Europe, the new find further documents the tropical fauna present during greenhouse conditions in the northern mid-latitudes approximately 50 million years ago (Ma). Modern Corytophanidae is a neotropical clade of iguanian lizards ranging from southern Mexico to northern South America.

  13. Ranavirus infections associated with skin lesions in lizards.

    Science.gov (United States)

    Stöhr, Anke C; Blahak, Silvia; Heckers, Kim O; Wiechert, Jutta; Behncke, Helge; Mathes, Karina; Günther, Pascale; Zwart, Peer; Ball, Inna; Rüschoff, Birgit; Marschang, Rachel E

    2013-09-27

    Ranaviral disease in amphibians has been studied intensely during the last decade, as associated mass-mortality events are considered to be a global threat to wild animal populations. Several studies have also included other susceptible ectothermic vertebrates (fish and reptiles), but only very few cases of ranavirus infections in lizards have been previously detected. In this study, we focused on clinically suspicious lizards and tested these animals for the presence of ranaviruses. Virological screening of samples from lizards with increased mortality and skin lesions over a course of four years led to the detection of ranaviral infections in seven different groups. Affected species were: brown anoles (Anolis sagrei), Asian glass lizards (Dopasia gracilis), green anoles (Anolis carolinensis), green iguanas (Iguana iguana), and a central bearded dragon (Pogona vitticeps). Purulent to ulcerative-necrotizing dermatitis and hyperkeratosis were diagnosed in pathological examinations. All animals tested positive for the presence of ranavirus by PCR and a part of the major capsid protein (MCP) gene of each virus was sequenced. Three different ranaviruses were isolated in cell culture. The analyzed portions of the MCP gene from each of the five different viruses detected were distinct from one another and were 98.4-100% identical to the corresponding portion of the frog virus 3 (FV3) genome. This is the first description of ranavirus infections in these five lizard species. The similarity in the pathological lesions observed in these different cases indicates that ranaviral infection may be an important differential diagnosis for skin lesions in lizards.

  14. Life-History Patterns of Lizards of the World.

    Science.gov (United States)

    Mesquita, Daniel O; Costa, Gabriel C; Colli, Guarino R; Costa, Taís B; Shepard, Donald B; Vitt, Laurie J; Pianka, Eric R

    2016-06-01

    Identification of mechanisms that promote variation in life-history traits is critical to understand the evolution of divergent reproductive strategies. Here we compiled a large life-history data set (674 lizard populations, representing 297 species from 263 sites globally) to test a number of hypotheses regarding the evolution of life-history traits in lizards. We found significant phylogenetic signal in most life-history traits, although phylogenetic signal was not particularly high. Climatic variables influenced the evolution of many traits, with clutch frequency being positively related to precipitation and clutches of tropical lizards being smaller than those of temperate species. This result supports the hypothesis that in tropical and less seasonal climates, many lizards tend to reproduce repeatedly throughout the season, producing smaller clutches during each reproductive episode. Our analysis also supported the hypothesis that viviparity has evolved in lizards as a response to cooler climates. Finally, we also found that variation in trait values explained by clade membership is unevenly distributed among lizard clades, with basal clades and a few younger clades showing the most variation. Our global analyses are largely consistent with life-history theory and previous results based on smaller and scattered data sets, suggesting that these patterns are remarkably consistent across geographic and taxonomic scales.

  15. Ranavirus infections associated with skin lesions in lizards

    Science.gov (United States)

    2013-01-01

    Ranaviral disease in amphibians has been studied intensely during the last decade, as associated mass-mortality events are considered to be a global threat to wild animal populations. Several studies have also included other susceptible ectothermic vertebrates (fish and reptiles), but only very few cases of ranavirus infections in lizards have been previously detected. In this study, we focused on clinically suspicious lizards and tested these animals for the presence of ranaviruses. Virological screening of samples from lizards with increased mortality and skin lesions over a course of four years led to the detection of ranaviral infections in seven different groups. Affected species were: brown anoles (Anolis sagrei), Asian glass lizards (Dopasia gracilis), green anoles (Anolis carolinensis), green iguanas (Iguana iguana), and a central bearded dragon (Pogona vitticeps). Purulent to ulcerative-necrotizing dermatitis and hyperkeratosis were diagnosed in pathological examinations. All animals tested positive for the presence of ranavirus by PCR and a part of the major capsid protein (MCP) gene of each virus was sequenced. Three different ranaviruses were isolated in cell culture. The analyzed portions of the MCP gene from each of the five different viruses detected were distinct from one another and were 98.4-100% identical to the corresponding portion of the frog virus 3 (FV3) genome. This is the first description of ranavirus infections in these five lizard species. The similarity in the pathological lesions observed in these different cases indicates that ranaviral infection may be an important differential diagnosis for skin lesions in lizards. PMID:24073785

  16. [The comparative aspects of spatial ecology of lizards exemplified by the toad-headed lizards (Reptilia, Agamidae, Phrynocephalus)].

    Science.gov (United States)

    Semenov, D V

    2007-01-01

    The possibility of analysis of phylogenetic parameters of the spatial distribution of populations is discussed by an example of the agamid toad-headed lizards (Phrynocephalus). Summarizing both original and published data on the individual home ranges and the relocation of individuals of 30 populations from 12 species showed that differentiation of the type of spatial distribution is weak in toad-headed lizards. This observation confirms the idea that this clade of agamids is phylogenetically young and relatively recently radiated. At the interspecific level, positive correlation between home range size and body size was observed in the studied group. Such spatial parameters, shared by all toad-headed lizards, as relatively large size and weakly structured individual home ranges can be explained by the peculiarities of their reproduction features and their foraging mode. The individual type of space-usage in toad-headed does not fit the traditional scheme dividing all the lizards into the territorial Iguania and the nonterritorial Autarchoglossa.

  17. Predictors of telomere content in dragon lizards

    Science.gov (United States)

    Ballen, Cissy; Healey, Mo; Wilson, Mark; Tobler, Michael; Olsson, Mats

    2012-08-01

    Telomeres shorten as a consequence of DNA replication, in particular in cells with low production of telomerase and perhaps in response to physiological stress from exposure to reactive oxygen species, such as superoxide. This process of telomere attrition is countered by innate antioxidation, such as via the production of superoxide dismutase. We studied the inheritance of telomere length in the Australian painted dragon lizard ( Ctenophorus pictus) and the extent to which telomere length covaries with mass-corrected maternal reproductive investment, which reflects the level of circulating yolk precursor and antioxidant, vitellogenin. Our predictors of offspring telomere length explained 72 % of telomere variation (including interstitial telomeres if such are present). Maternal telomere length and reproductive investment were positively influencing offspring telomere length in our analyses, whereas flow cytometry-estimated superoxide level was negatively impacting offspring telomere length. We suggest that the effects of superoxide on hatchling telomere shortening may be partly balanced by transgenerational effects of vitellogenin antioxidation.

  18. [Ultrastructure of the "rudimentary secretory photoreceptors" (RSP) of the embryonic pineal body of Lacerta vivipara J. (Reptilia, Lacertilia) and the origin of the RSP of Sauropsida].

    Science.gov (United States)

    Meiniel, A

    1975-10-20

    The "secretory rudimentary photoreceptor-cells" of Lacerta vivipara J., during embryonic stages, exhibit photosensory differentiations (disks). Our ontogenetic observations agree with the phylogenetic studies and support the concept of a "sensory cell line" (Colin, 1969) in the pineal organ of vertebrates.

  19. Sédentarité, déplacements et répartition des individus dans une population de Lacerta viridis (Laurenti, 1768) (Lacertilia, Lacertidae)

    NARCIS (Netherlands)

    Girons, Saint H.; Bradshaw, S.D.

    1989-01-01

    A mark-and-recapture study was undertaken in August 1983, May and September 1987, and May 1988 of a small discrete population of Lacerta viridis occupying an area of 260 x 11—25 m, along the length of a canal in western France. A total of 21 recaptures, over periods of time varying from four months

  20. Absolute Population Densities of the Lizards of Ritidian Point, Guam National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Intensive sampling for lizards of Guam NWR at Ritidian Point using a total removal methodology quantifies the lizard fauna in unprecedented detail, providing...

  1. Bituminous sands : tax issues

    Energy Technology Data Exchange (ETDEWEB)

    Patel, B. [PricewaterhouseCoopers LLP, Calgary, AB (Canada)

    2004-07-01

    This paper examined some of the tax issues associated with the production of bitumen or synthetic crude oil from oil sands. The oil sands deposits in Alberta are gaining more attention as the supplies of conventional oil in Canada decline. The oil sands reserves located in the Athabasca, Cold Lake and Peace River areas contain about 2.5 trillion barrels of highly viscous hydrocarbons called bitumen, of which nearly 315 billion barrels are recoverable with current technology. The extraction method varies for each geographic area, and even within zones and reservoirs. The two most common extraction methods are surface mining and in-situ extraction such as cyclic steam stimulation (CSS); low pressure steam flood; pressure cycle steam drive; steam assisted gravity drainage (SAGD); hot water flooding; and, fire flood. This paper also discussed the following general tax issues: bituminous sands definition; bituminous sands leases and Canadian development expense versus Canadian oil and gas property expense (COGPE); Canadian exploration expense (CEE) for surface mining versus in-situ methods; additional capital cost allowance; and, scientific research and experimental development (SR and ED). 15 refs.

  2. The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT

    Science.gov (United States)

    Raiteri, C. M.; Villata, M.; D'Ammando, F.; Larionov, V. M.; Gurwell, M. A.; Mirzaqulov, D. O.; Smith, P. S.; Acosta-Pulido, J. A.; Agudo, I.; Arévalo, M. J.; Bachev, R.; Benítez, E.; Berdyugin, A.; Blinov, D. A.; Borman, G. A.; Böttcher, M.; Bozhilov, V.; Carnerero, M. I.; Carosati, D.; Casadio, C.; Chen, W. P.; Doroshenko, V. T.; Efimov, Yu. S.; Efimova, N. V.; Ehgamberdiev, Sh. A.; Gómez, J. L.; González-Morales, P. A.; Hiriart, D.; Ibryamov, S.; Jadhav, Y.; Jorstad, S. G.; Joshi, M.; Kadenius, V.; Klimanov, S. A.; Kohli, M.; Konstantinova, T. S.; Kopatskaya, E. N.; Koptelova, E.; Kimeridze, G.; Kurtanidze, O. M.; Larionova, E. G.; Larionova, L. V.; Ligustri, R.; Lindfors, E.; Marscher, A. P.; McBreen, B.; McHardy, I. M.; Metodieva, Y.; Molina, S. N.; Morozova, D. A.; Nazarov, S. V.; Nikolashvili, M. G.; Nilsson, K.; Okhmat, D. N.; Ovcharov, E.; Panwar, N.; Pasanen, M.; Peneva, S.; Phipps, J.; Pulatova, N. G.; Reinthal, R.; Ros, J. A.; Sadun, A. C.; Schwartz, R. D.; Semkov, E.; Sergeev, S. G.; Sigua, L. A.; Sillanpää, A.; Smith, N.; Stoyanov, K.; Strigachev, A.; Takalo, L. O.; Taylor, B.; Thum, C.; Troitsky, I. S.; Valcheva, A.; Wehrle, A. E.; Wiesemeyer, H.

    2013-12-01

    Since the launch of the Fermi satellite, BL Lacertae has been moderately active at γ-rays and optical frequencies until 2011 May, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily γ-ray observations by Fermi. Discrete correlation analysis between the optical and γ-ray emission reveals correlation with a time lag of 0 ± 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time-scales than corresponding γ-ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiation is located downstream from the optical and γ-ray-emitting zone in the jet. The mean optical degree of polarization slightly decreases over the considered period and in general it is higher when the flux is lower. The optical electric vector polarization angle (EVPA) shows a preferred orientation of about 15°, nearly aligned with the radio core EVPA and mean jet direction. Oscillations around it increase during the 2011-2012 outburst. We investigate the effects of a geometrical interpretation of the long-term flux variability on the polarization. A helical magnetic field model predicts an evolution of the mean polarization that is in reasonable agreement with the observations. These can be fully explained by introducing slight variations in the compression factor in a transverse shock waves model.

  3. Is BZB J1450+5201 the most distant gamma-ray BL Lacertae object?

    Science.gov (United States)

    Liao, Neng-Hui; Bai, Jin-Ming; Wang, Jian-Guo; Liu, Hong-Tao; Zhang, Jiu-Jia; Jiang, Ning; Yuan, Zun-Li; Chen, Liang

    2015-03-01

    BL Lacertae (BL Lac) objects at high redshifts (z ≥ 2) are rarely detected. Through careful analysis of its Sloan Digital Sky Survey spectrum, BZB J1450+5201 is confirmed to be a high-z BL Lac object with z ≥ 2.471 by identifying the Lyα 1216 and CIV 1548/1550 absorption lines. This indicates that BZB J1450+5201 is the most distant BL Lac object discovered to date. Careful analysis of the five-year Fermi-LAT data of 2FGL J1451.0+5159 shows that its γ-ray emission is robust with a confidence level of 6.2σ at 1-3 GeV and 6.7σ at 3-10 GeV. This analysis with the five-year data overcomes confusion with its bright neighbor, which is a problem when analyzing the two-year data. In addition, 2FGL J1451.0+5159 is confirmed to be associated with BZB J1450+5201 using the five-year data. The analysis of multiwavelength data, from radio to γ-ray energies, indicates that BZB J1450+5201 is an intermediate synchrotron peaked (ISP) source. Its multiwavelength properties are consistent with distributions of other ISP sources at lower redshifts in the second Fermi-LAT AGN catalog. The pure synchrotron self-Compton (SSC) model seems to be disfavored, but the scattering of weak external emission plus the SSC process can provide a satisfactory description of the broadband emission. Supported by the National Natural Science Foundation of China.

  4. Varicus lacerta, a new species of goby (Teleostei, Gobiidae, Gobiosomatini, Nes subgroup) from a mesophotic reef in the southern Caribbean.

    Science.gov (United States)

    Tornabene, Luke; Robertson, D Ross; Baldwin, Carole C

    2016-01-01

    We describe a new species of goby, Varicus lacerta sp. n., which was collected from a mesophotic reef at Curacao, southern Caribbean. The new species is the tenth species of Varicus, all of which occur below traditional SCUBA depths in the wider Caribbean area. Its placement in the genus Varicus is supported by a molecular phylogenetic analysis of three nuclear genes and the mitochondrial gene cytochrome b. In addition, the new species has one anal-fin pterygiophore inserted anterior to the first haemal spine, which distinguishes Varicus species from most species in the closely related and morphologically similar genus Psilotris. Varicus lacerta sp. n. is distinguished from all other named species of Varicus by the absence of scales, having highly branched, feather-like pelvic-fin rays, and in its live coloration. We provide the cytochrome c oxidase I DNA barcode of the holotype and compare color patterns of all species of Varicus and Psilotris for which color photographs or illustrations are available. This study is one of several recent studies demonstrating the utility of manned submersibles in exploring the diversity of poorly studied but species-rich deep-reef habitats.

  5. Artificial Water Point for Livestock Influences Spatial Ecology of a Native Lizard Species

    OpenAIRE

    Leu, Stephan T.; C Michael Bull

    2016-01-01

    Pastoralism is a major agricultural activity in drier environments, and can directly and indirectly impact native species in those areas. We investigated how the supply of an artificial watering point to support grazing livestock affected movement and activity patterns of the Australian sleepy lizard (Tiliqua rugosa) during a drought year. We observed 23 adult lizards; six had access to a dam, whereas 17 lizards did not. Lizards with access to the dam had larger home ranges, were substantiall...

  6. Lund Sand No 0

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Jakobsen, Finn Rosendal

    During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve...... test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. The Danish Triaxial Cell prescribes smooth pressure heads and specimens with equal height and diameter....... Four series with Id equal to 0.92, 0.87 0.76 and 0.55 have been performed....

  7. UK Frac Sand Resources

    OpenAIRE

    Mitchell, C J

    2015-01-01

    Although still just a glimmer in the gas man’s eye, the prospect of shale hydrocarbon (oil and gas) development in the UK has many companies thinking about the industrial minerals it will require. Chief amongst these is silica sand which is used as a ‘proppant’ in the hydraulic fracturing, or ‘fracking’, of shales to help release the gas. The UK has large resources of sand and sandstone, of which only a small proportion have the necessary technical properties that classify them as ‘silica san...

  8. Spatial, ontogenetic and sexual effects on the diet of a Teiid lizard in arid South America

    NARCIS (Netherlands)

    Leeuwen, van J.P.; Catenazzi, A.; Holmgren, M.

    2011-01-01

    Most lizard species feed on small arthropods, and although some are omnivorous, only a few species are strict herbivores. We studied the diet of Dicrodon guttulatum, a teiid lizard endemic to the arid coastal deserts and dry forests of northern Peru. Herbivory by this lizard has been identified as a

  9. Artificial Water Point for Livestock Influences Spatial Ecology of a Native Lizard Species.

    Directory of Open Access Journals (Sweden)

    Stephan T Leu

    Full Text Available Pastoralism is a major agricultural activity in drier environments, and can directly and indirectly impact native species in those areas. We investigated how the supply of an artificial watering point to support grazing livestock affected movement and activity patterns of the Australian sleepy lizard (Tiliqua rugosa during a drought year. We observed 23 adult lizards; six had access to a dam, whereas 17 lizards did not. Lizards with access to the dam had larger home ranges, were substantially active on more days (days with >100 steps, and moved more steps per day compared to lizards that did not have access to the dam, both during the early and late period of our observation. Furthermore, while the two groups of lizards had similar body condition early in the season, they differed later in the season. Lizards with dam access retained, whereas lizards without access lost body condition. Local heterogeneity in access to an artificial water resource resulted in spatially dependent behavioural variation among sleepy lizard individuals. This suggests that sleepy lizards have flexible responses to changing climatic conditions, depending on the availability of water. Furthermore, while reducing activity appears a suitable short term strategy, if harsh conditions persist, then access to dams could be of substantial benefit and could support sustained lizard activity and movement and allow maintenance of body condition. Hence, artificial watering points, such as the dams constructed by pastoralists, may provide local higher quality refugia for sleepy lizards and other species during drought conditions.

  10. Artificial Water Point for Livestock Influences Spatial Ecology of a Native Lizard Species.

    Science.gov (United States)

    Leu, Stephan T; Bull, C Michael

    2016-01-01

    Pastoralism is a major agricultural activity in drier environments, and can directly and indirectly impact native species in those areas. We investigated how the supply of an artificial watering point to support grazing livestock affected movement and activity patterns of the Australian sleepy lizard (Tiliqua rugosa) during a drought year. We observed 23 adult lizards; six had access to a dam, whereas 17 lizards did not. Lizards with access to the dam had larger home ranges, were substantially active on more days (days with >100 steps), and moved more steps per day compared to lizards that did not have access to the dam, both during the early and late period of our observation. Furthermore, while the two groups of lizards had similar body condition early in the season, they differed later in the season. Lizards with dam access retained, whereas lizards without access lost body condition. Local heterogeneity in access to an artificial water resource resulted in spatially dependent behavioural variation among sleepy lizard individuals. This suggests that sleepy lizards have flexible responses to changing climatic conditions, depending on the availability of water. Furthermore, while reducing activity appears a suitable short term strategy, if harsh conditions persist, then access to dams could be of substantial benefit and could support sustained lizard activity and movement and allow maintenance of body condition. Hence, artificial watering points, such as the dams constructed by pastoralists, may provide local higher quality refugia for sleepy lizards and other species during drought conditions.

  11. Spatial, ontogenetic and sexual effects on the diet of a Teiid lizard in arid South America

    NARCIS (Netherlands)

    Leeuwen, van J.P.; Catenazzi, A.; Holmgren, M.

    2011-01-01

    Most lizard species feed on small arthropods, and although some are omnivorous, only a few species are strict herbivores. We studied the diet of Dicrodon guttulatum, a teiid lizard endemic to the arid coastal deserts and dry forests of northern Peru. Herbivory by this lizard has been identified as a

  12. The Ins & Outs of Developing a Field-Based Science Project: Learning by Lassoing Lizards

    Science.gov (United States)

    Matthews, Catherine E.; Huffling, Lacey D.; Benavides, Aerin

    2014-01-01

    We describe a field-based lizard project we did with high school students as a part of our summer Herpetological Research Experiences. We describe data collection on lizards captured, identified, and marked as a part of our mark-recapture study. We also describe other lizard projects that are ongoing in the United States and provide resources for…

  13. 76 FR 62087 - Draft Conservation Plan and Draft Environmental Assessment; Dunes Sagebrush Lizard, Texas

    Science.gov (United States)

    2011-10-06

    ... Lizard, Texas AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of availability; announcement... application includes the draft Texas Conservation Plan for the Dunes Sagebrush Lizard (TCP). The draft TCP... Service (Service) and the Applicant for the dunes sagebrush lizard (Sceloporus arenicolus) throughout...

  14. Spontaneous otoacoustic emissions in lizards: a comparison of the skink-like lizard families Cordylidae and Gerrhosauridae.

    Science.gov (United States)

    Manley, Geoffrey A

    2009-09-01

    Lizard families can be grouped into larger units comprising those families that are closely related and whose auditory papillae are morphologically very similar. Based on the few species studied at that time [Manley, G.A., 1997. Diversity in hearing-organ structure and the characteristics of spontaneous otoacoustic emissions in lizards. In: Lewis, E.R., Long, G.R., Lyon, R.F., Narins, P.M., Steele, C.R. (Eds.), Diversity in Auditory Mechanics. World Scientific Publishing Co., Singapore, pp. 32-38], it was suggested that SOAE spectral patterns are strongly influenced by papillar anatomy. However, in two family groups, only one single species has been studied and we have no data on the regularity of pattern within related lizard families. Within the group of skink-like lizards, whose papillae all have salletal tectorial structures, the only detailed SOAE studies so far were on the skink genus Tiliqua. To ascertain the similarity of SOAE in species from families related to the skinks, we have studied one species each from two families that are closely related to skinks, the Cordylidae (Girdle-tailed lizards) and the Gerrhosauridae (plated lizards). Gerrhosaurus and Cordylus have a similar number and amplitudes of SOAE to Tiliqua (Skinkidae). The maximal frequency shifts of SOAE under the influence of external tones is also similar to that of Tiliqua. However, the maximal suppression and maximal facilitation are smaller. In general, the patterns displayed by the SOAE of lizards of these two new families are recognizably similar to the skink Tiliqua, suggesting that the anatomy of the papilla and the tectorial structures do play an important role in determining how SOAE are manifested in papillae that possess tectorial sallets.

  15. Building with Sand

    Science.gov (United States)

    Ashbrook, Peggy

    2010-01-01

    Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of…

  16. Faraday, Jets, and Sand

    NARCIS (Netherlands)

    Sandtke, M.; van der Meer, Roger M.; Versluis, Andreas Michel; Lohse, Detlef

    2003-01-01

    When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical container and shaken vertically, thin jets are seen to emerge from an airy cloud of grains, almost like protuberances from the corona of the sun. A quasi two-dimensional setup reveals the jet-formation

  17. Building with Sand

    Science.gov (United States)

    Ashbrook, Peggy

    2010-01-01

    Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of…

  18. Speleothems and Sand Castles

    Science.gov (United States)

    Hance, Trevor; Befus, Kevin

    2015-01-01

    The idea of building sand castles evokes images of lazy summer days at the beach, listening to waves crash, enjoying salty breezes, and just unplugging for a while to let our inner child explore the wonderful natural toys beneath our feet. The idea of exploring caves might evoke feelings and images of claustrophobia or pioneers and Native…

  19. Virksomhedens sande ansigt

    DEFF Research Database (Denmark)

    Lundholt, Marianne Wolff

    2017-01-01

    Er modhistorier en byrde eller en styrke i forandringsprocesser? Hvad stiller vi op, når adgangen til organisationens sande identitet går gennem medarbejdernes modhistorier? Når vi sammenholder denne erkendelse med vores viden om, at medarbejdere helt naturligt afholder sig fra at videregive disse...

  20. Sand (CSW4)

    CSIR Research Space (South Africa)

    Estuarine and Coastal Research Unit

    1982-12-01

    Full Text Available This report is one of a series on Cape Estuaries being published under the general title "The Estuaries of the Cape, Part 2". The report provides information on sand estuary: historical background, abiotic and biotic characteristics. It is pointed...

  1. Sand supply to beaches

    Science.gov (United States)

    Aagaard, Troels

    2017-04-01

    In most cases, beaches and dunes are built by sand that has been transported onshore from the shoreface. While this has been known for a long time, we are still not able to quantitatively predict onshore sediment transport and sand supply to beaches. Sediment transport processes operating during brief, high-energy stormy conditions - when beaches erode and sand moves offshore - are fairly well known and they can be modelled with a reasonable degree of confidence. However, the slower onshore sand transport leading to beach recovery under low-to-moderate energy conditions - and the reason why beaches and dunes exist in the first place - is not yet well understood. This severely limits our capability to understand and predict coastal behaviour on long time scales, for example in response to changing sea level or wave conditions. This paper will discuss issues and recent developments in sediment transport measurement and prediction on the lower and upper shoreface and into the swash zone. The focus will be on the integration and upscaling of small-scale deterministic process measurements into parametric models that may increase modelling capabilities of coastal behaviour on larger temporal and spatial scales.

  2. Wind constraints on the thermoregulation of high mountain lizards.

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2017-03-01

    Thermal biology of lizards affects their overall physiological performance. Thus, it is crucial to study how abiotic constraints influence thermoregulation. We studied the effect of wind speed on thermoregulation in an endangered mountain lizard (Iberolacerta aurelioi). We compared two populations of lizards: one living in a sheltered rocky area and the other living in a mountain ridge, exposed to strong winds. The preferred temperature range of I. aurelioi, which reflects thermal physiology, was similar in both areas, and it was typical of a cold specialist. Although the thermal physiology of lizards and the structure of the habitat were similar, the higher wind speed in the exposed population was correlated with a significant decrease in the effectiveness thermoregulation, dropping from 0.83 to 0.74. Our results suggest that wind reduces body temperatures in two ways: via direct convective cooling of the animal and via convective cooling of the substrate, which causes conductive cooling of the animal. The detrimental effect of wind on thermoregulatory effectiveness is surprising, since lizards are expected to thermoregulate more effectively in more challenging habitats. However, wind speed would affect the costs and benefits of thermoregulation in more complex ways than just the cooling of animals and their habitats. For example, it may reduce the daily activity, increase desiccation, or complicate the hunting of prey. Finally, our results imply that wind should also be considered when developing conservation strategies for threatened ectotherms.

  3. A genome draft of the legless anguid lizard, Ophisaurus gracilis.

    Science.gov (United States)

    Song, Bo; Cheng, Shifeng; Sun, Yanbo; Zhong, Xiao; Jin, Jieqiong; Guan, Rui; Murphy, Robert W; Che, Jing; Zhang, Yaping; Liu, Xin

    2015-01-01

    Transition from a lizard-like to a snake-like body form is one of the most important transformations in reptilian evolution. The increasing number of sequenced reptilian genomes is enabling a deeper understanding of vertebrate evolution, although the genetic basis of the loss of limbs in reptiles remains enigmatic. Here we report genome sequencing, assembly, and annotation for the Asian glass lizard Ophisaurus gracilis, a limbless lizard species with an elongated snake-like body form. Addition of this species to the genome repository will provide an excellent resource for studying the genetic basis of limb loss and trunk elongation. O. gracilis genome sequencing using the Illumina HiSeq2000 platform resulted in 274.20 Gbp of raw data that was filtered and assembled to a final size of 1.78 Gbp, comprising 6,717 scaffolds with N50 = 1.27 Mbp. Based on the k-mer estimated genome size of 1.71 Gbp, the assembly appears to be nearly 100% complete. A total of 19,513 protein-coding genes were predicted, and 884.06 Mbp of repeat sequences (approximately half of the genome) were annotated. The draft genome of O. gracilis has similar characteristics to both lizard and snake genomes. We report the first genome of a lizard from the family Anguidae, O. gracilis. This supplements currently available genetic and genomic resources for amniote vertebrates, representing a major increase in comparative genome data available for squamate reptiles in particular.

  4. Experimental infections in Venezuelan lizards by Trypanosoma cruzi.

    Science.gov (United States)

    Urdaneta-Morales, S; McLure, I

    1981-06-01

    Virulent trypomastigotes of the Y strain of Trypanosoma cruzi were administered to Tropidurus hispidus, Ameiva ameiva, Cnemidophorus lemniscatus, Polychrus marmoratus, and Phyllodactylus ventralis (Sauria). Intraperitoneal and subcutaneous inoculations of lizards with mouse blood or with feces of infected Rhodnius prolixus (Reduviidae, Triatominae), as well as forced ingestion of triturated Rhodnius, produced no parasitaemias detectable either directly or by xenodiagnosis, while control mice became parasitized. Pretreatment with the immunosuppressive drug Fluocinolone acetonide led to establishing patent infections in inoculated lizards. Cryptic infections were established by inoculation of 1 X 10(6) parasites from Davis' medium, or by 95 X 10(3) parasites from lizard tissue culture. Parasites were not seen in tissues. Mice inoculated with blood or tissue homogenates from these lizards became parasitized. Parasites from Davis' medium inoculated into the peritoneal cavity of lizards were capable, to a very low degree, of penetrating the free peritoneal macrophages and changing into amastigotes. The factors possibly responsible for the natural resistance of poikilothermic vertebrates to T. cruzi are discussed.

  5. Effects of inorganic lead on Western fence lizards (Sceloporus occidentalis)

    Energy Technology Data Exchange (ETDEWEB)

    Salice, Christopher J., E-mail: chris.salice@ttu.ed [US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD 21010 (United States); Suski, Jamie G., E-mail: jamie.suski@ttu.ed [US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD 21010 (United States); Bazar, Matthew A., E-mail: matthew.bazar@us.army.mi [US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, MD 21010 (United States); Talent, Larry G., E-mail: larry.talent@okstate.ed [Oklahoma State University, Department of Natural Resource Ecology and Management, Stillwater, OK 74078 (United States)

    2009-12-15

    Although anthropogenic pollutants are thought to threaten reptilian species, there are few toxicity studies on reptiles. We evaluated the toxicity of Pb as lead acetate to the Western fence lizard (Sceloporus occidentalis). The acute lethal dose and sub-acute (14-day) toxicity studies were used to narrow exposure concentrations for a sub-chronic (60-day) study. In the sub-chronic study, adult and juvenile male lizards were dosed via gavage with 0, 1, 10 and 20 mg Pb/kg-bw/day. Mortality was limited and occurred only at the highest dose (20 mg Pb/kg-bw/d). There were statistically significant sub-lethal effects of 10 and 20 mg Pb/kg-bw/d on body weight, cricket consumption, organ weight, hematological parameters and post-dose behaviors. Of these, Pb-induced changes in body weight are most useful for ecological risk assessment because it is linked to fitness in wild lizard populations. The Western fence lizard is a useful model for reptilian toxicity studies. - The Western fence lizard, Sceloporus occidentalis, is sensitive to Pb and is a useful laboratory model for ecotoxicological testing of reptiles.

  6. Nereididae (Annelida: Phyllodocida) of Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Glasby, Christopher J

    2015-09-18

    Nereididae is one of the most ubiquitous of polychaete families, yet knowledge of their diversity in the northern Great Barrier Reef is poor; few species have been previously reported from any of the atolls or islands including Lizard Island. In this study, the diversity of the family from Lizard Island and surrounding reefs is documented based on museum collections derived from surveys conducted mostly over the last seven years. The Lizard Island nereidid fauna was found to be represented by 14 genera and 38 species/species groups, including 11 putative new species. Twelve species are newly reported from Lizard Island; four of these are also first records for Australia. For each genus and species, diagnoses and/or taxonomic remarks are provided in addition to notes on their habitat on Lizard Island, and general distribution; the existence of tissue samples tied to vouchered museum specimens is indicated. Fluorescence photography is used to help distinguish closely similar species of Nereis and Platynereis. A key is provided to facilitate identification and encourage further taxonomic, molecular and ecological studies on the group.

  7. Wind constraints on the thermoregulation of high mountain lizards

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2017-03-01

    Thermal biology of lizards affects their overall physiological performance. Thus, it is crucial to study how abiotic constraints influence thermoregulation. We studied the effect of wind speed on thermoregulation in an endangered mountain lizard ( Iberolacerta aurelioi). We compared two populations of lizards: one living in a sheltered rocky area and the other living in a mountain ridge, exposed to strong winds. The preferred temperature range of I. aurelioi, which reflects thermal physiology, was similar in both areas, and it was typical of a cold specialist. Although the thermal physiology of lizards and the structure of the habitat were similar, the higher wind speed in the exposed population was correlated with a significant decrease in the effectiveness thermoregulation, dropping from 0.83 to 0.74. Our results suggest that wind reduces body temperatures in two ways: via direct convective cooling of the animal and via convective cooling of the substrate, which causes conductive cooling of the animal. The detrimental effect of wind on thermoregulatory effectiveness is surprising, since lizards are expected to thermoregulate more effectively in more challenging habitats. However, wind speed would affect the costs and benefits of thermoregulation in more complex ways than just the cooling of animals and their habitats. For example, it may reduce the daily activity, increase desiccation, or complicate the hunting of prey. Finally, our results imply that wind should also be considered when developing conservation strategies for threatened ectotherms.

  8. Wind constraints on the thermoregulation of high mountain lizards

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-08-01

    Thermal biology of lizards affects their overall physiological performance. Thus, it is crucial to study how abiotic constraints influence thermoregulation. We studied the effect of wind speed on thermoregulation in an endangered mountain lizard (Iberolacerta aurelioi). We compared two populations of lizards: one living in a sheltered rocky area and the other living in a mountain ridge, exposed to strong winds. The preferred temperature range of I. aurelioi, which reflects thermal physiology, was similar in both areas, and it was typical of a cold specialist. Although the thermal physiology of lizards and the structure of the habitat were similar, the higher wind speed in the exposed population was correlated with a significant decrease in the effectiveness thermoregulation, dropping from 0.83 to 0.74. Our results suggest that wind reduces body temperatures in two ways: via direct convective cooling of the animal and via convective cooling of the substrate, which causes conductive cooling of the animal. The detrimental effect of wind on thermoregulatory effectiveness is surprising, since lizards are expected to thermoregulate more effectively in more challenging habitats. However, wind speed would affect the costs and benefits of thermoregulation in more complex ways than just the cooling of animals and their habitats. For example, it may reduce the daily activity, increase desiccation, or complicate the hunting of prey. Finally, our results imply that wind should also be considered when developing conservation strategies for threatened ectotherms.

  9. Erosion phenomena in sand moulds

    Directory of Open Access Journals (Sweden)

    A. Chojecki

    2008-03-01

    Full Text Available Authors studicd the erosion phcnorncna in sand moulds pured with cast iron. Thc study comprises an evaluation of erosionresistance of thc three sands: grccn sand. sand bondcd with inorganic or organic bindcr. It was concluded that thc most resistant is [heclassic green sand with thc addition of 5 B coal dust. Resistance of the sand with organic binder is generally weak and dcvnds onkind of used raisin. Spccinl nztcntion was paid to the sands with no organic bindcr watcr glass and phospha~c. It was Sound that thcirrcsistance depends on dehydratation conditions. When the mould is stored in law humidity of atmosphcrc the very strong crosion canbe expected. It rcsul ts hrn thc micro fractures in the bridges of binders, joining the grains of the sable. This phcnomcna facilitates thetearing away of fragments of sand [tom the surface

  10. On Pluvial Compaction of Sand

    DEFF Research Database (Denmark)

    Jacobsen, Moust

    At the Institute of Civil Engineering in Aalborg model tests on dry sand specimens have been carried out during the last five years. To reduce deviations in test results, the sand laying technique has been carefully studied, and the sand mass spreader constructed. Preliminary results have been...

  11. High sensitivity to short wavelengths in a lizard and implications for understanding the evolution of visual systems in lizards.

    Science.gov (United States)

    Fleishman, Leo J; Loew, Ellis R; Whiting, Martin J

    2011-10-07

    Progress in developing animal communication theory is frequently constrained by a poor understanding of sensory systems. For example, while lizards have been the focus of numerous studies in visual signalling, we only have data on the spectral sensitivities of a few species clustered in two major clades (Iguania and Gekkota). Using electroretinography and microspectrophotometry, we studied the visual system of the cordylid lizard Platysaurus broadleyi because it represents an unstudied clade (Scinciformata) with respect to visual systems and because UV signals feature prominently in its social behaviour. The retina possessed four classes of single and one class of double cones. Sensitivity in the ultraviolet region (UV) was approximately three times higher than previously reported for other lizards. We found more colourless oil droplets (associated with UV-sensitive (UVS) and short wavelength-sensitive (SWS) photoreceptors), suggesting that the increased sensitivity was owing to the presence of more UVS photoreceptors. Using the Vorobyev-Osorio colour discrimination model, we demonstrated that an increase in the number of UVS photoreceptors significantly enhances a lizard's ability to discriminate conspecific male throat colours. Visual systems in diurnal lizards appear to be broadly conserved, but data from additional clades are needed to confirm this.

  12. Tail regeneration affects the digestive performance of a Mediterranean lizard

    Science.gov (United States)

    Sagonas, Kostas; Karambotsi, Niki; Bletsa, Aristoula; Reppa, Aikaterini; Pafilis, Panayiotis; Valakos, Efstratios D.

    2017-04-01

    In caudal autotomy, lizards shed their tail to escape from an attacking predator. Since the tail serves multiple functions, caudal regeneration is of pivotal importance. However, it is a demanding procedure that requires substantial energy and nutrients. Therefore, lizards have to increase energy income to fuel the extraordinary requirements of the regenerating tail. We presumed that autotomized lizards would adjust their digestion to acquire this additional energy. To clarify the effects of tail regeneration on digestion, we compared the digestive performance before autotomy, during regeneration, and after its completion. Tail regeneration indeed increased gut passage time but did not affect digestive performance in a uniform pattern: though protein income was maximized, lipid and sugar acquisition remained stable. This divergence in proteins may be attributed to their particular role in tail reconstruction, as they are the main building blocks for tissue formation.

  13. Serpulidae (Annelida) of Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Kupriyanova, Elena K; Sun, Yanan; Hove, Harry A Ten; Wong, Eunice; Rouse, Greg W

    2015-09-18

    Serpulidae are obligatory sedentary polychaetes inhabiting calcareous tubes that are most common in subtropical and tropical areas of the world. This paper describes serpulid polychaetes collected from Lizard Island, Great Barrier Reef, Australia in 1983-2013 and deposited in Australian museums and overseas. In total, 17 serpulid genera were recorded, but although the study deals with 44 nominal taxa, the exact number of species remains unclear because a number of genera (i.e., Salmacina, Protula, Serpula, Spirobranchus, and Vermiliopsis) need world-wide revisions. Some species described herein are commonly found in the waters around Lizard Island, but had not previously been formally reported. A new species of Hydroides (H. lirs) and two new species of Semivermilia (S. annehoggettae and S. lylevaili) are described. A taxonomic key to all taxa found at Lizard Island is provided.

  14. Compositional Studies on Tropical Species of Agama agama Lizards

    Directory of Open Access Journals (Sweden)

    V.O. Onibon

    2007-01-01

    Full Text Available The aim of this study was to assess nutrient values of lizards (Agama agama. The samples earmarked for this study were obtained at Federal College of Agriculture, Akure, Nigeria. In male and female Agama agama lizards, anatomical weights, proximate and mineral contents, tannin, oxalate and phytate compositions were determined using standard methods. The samples contained: 54.05-57.69% protein; 2.56-3.01% fat, 1.11-3.18% fibre, 12.91-13.40% ash, 21.38-21.94% NFE, 3.85-4.18% moisture and 328.80-347.5 kcal energy. All the major elements determined were found to be high. The tannin, oxalate, phytate contents were low, meaning that the bioavailability of protein and minerals are high. The values recorded for proximate and minerals compared with other animal sources. It is recommended that nutritional qualities of lizards should be harnessed.

  15. Oxidative stress decreases with elevation in the lizard Psammodromus algirus.

    Science.gov (United States)

    Reguera, Senda; Zamora-Camacho, Francisco J; Trenzado, Cristina E; Sanz, Ana; Moreno-Rueda, Gregorio

    2014-06-01

    Oxidative stress is considered one of the main ecological and evolutionary forces. Several environmental stressors vary geographically and thus organisms inhabiting different sites face different oxidant environments. Nevertheless, there is scarce information about how oxidative damage and antioxidant defences vary geographically in animals. Here we study how oxidative stress varies from lowlands (300-700 m asl) to highlands (2200-2500 m asl) in the lizard Psammodromus algirus. To accomplish this, antioxidant enzymatic activity (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase) and lipid peroxidation were assayed in tissue samples from the lizards' tail. Lipid peroxidation was higher in individuals from lowlands than from highlands, indicating higher oxidative stress in lowland lizards. These results suggest that environmental conditions are less oxidant at high elevations with respect to low ones. Therefore, our study shows that oxidative stress varies geographically, which should have important consequences for our understanding of geographic variation in physiology and life-history of organisms.

  16. Seasonal reproductive endothermy in tegu lizards.

    Science.gov (United States)

    Tattersall, Glenn J; Leite, Cleo A C; Sanders, Colin E; Cadena, Viviana; Andrade, Denis V; Abe, Augusto S; Milsom, William K

    2016-01-01

    With some notable exceptions, small ectothermic vertebrates are incapable of endogenously sustaining a body temperature substantially above ambient temperature. This view was challenged by our observations of nighttime body temperatures sustained well above ambient (up to 10°C) during the reproductive season in tegu lizards (~2 kg). This led us to hypothesize that tegus have an enhanced capacity to augment heat production and heat conservation. Increased metabolic rates and decreased thermal conductance are the same mechanisms involved in body temperature regulation in those vertebrates traditionally acknowledged as "true endotherms": the birds and mammals. The appreciation that a modern ectotherm the size of the earliest mammals can sustain an elevated body temperature through metabolic rates approaching that of endotherms enlightens the debate over endothermy origins, providing support for the parental care model of endothermy, but not for the assimilation capacity model of endothermy. It also indicates that, contrary to prevailing notions, ectotherms can engage in facultative endothermy, providing a physiological analog in the evolutionary transition to true endothermy.

  17. Effects of Surface Roughness on the Locomotion of a Long-Tailed Lizard, Colobodactylus taunayi Amaral, 1933 (Gymnophthalmidae: Heterodactylini

    Directory of Open Access Journals (Sweden)

    Elizabeth Höfling

    2012-01-01

    Full Text Available We analyzed the locomotor behavior of a long-tailed, forest floor, and leaf litter lizard, Colobodactylus taunayi, a species that retains the generalized Gymnophthalmidae Bauplan whilst presenting the discrete toe reduction associated with the Bachia-like pattern of limb reduction. We videotaped individuals moving on four substrates with increasing degrees of roughness: plastic, wooden board, glued sand, and glued gravel. Significantly higher speeds occurred on the last two substrates. As with most other limbed animals, increased speed was significantly correlated with simultaneous increases in both stride length and stride frequency. Independently of the kind of substrate, C. taunayi used rather slow lateral sequence walking trots. In contrast to other ectothermic tetrapods, and especially other Gymnophthalmidae, this species lacked perceptible lateral flexion of either the trunk or the tail to effectuate these slow gaits.

  18. Does thermal ecology influence dynamics of side-blotched lizards and their micro-parasites?

    Science.gov (United States)

    Paranjpe, Dhanashree A; Medina, Dianna; Nielsen, Erica; Cooper, Robert D; Paranjpe, Sharayu A; Sinervo, Barry

    2014-07-01

    Hosts and parasites form interacting populations that influence each other in multiple ways. Their dynamics can also be influenced by environmental and ecological factors. We studied host-parasite dynamics in a previously unexplored study system: side-blotched lizards and their micro-parasites. Compared with uninfected lizards, the infected lizards elected to bask at lower temperatures that were outside their range of preferred temperatures. Infected lizards also were not as precise as uninfected lizards in maintaining their body temperatures within a narrow range. At the ecological scale, areas with higher infection rates coincided with more thermally heterogeneous microhabitats as well as with the areas where lizards tended to live longer. Thermal heterogeneity of lizards' microhabitats may provide important clues to the spatial and temporal distribution of infections.

  19. Earliest example of a giant monitor lizard (Varanus, Varanidae, Squamata.

    Directory of Open Access Journals (Sweden)

    Jack L Conrad

    Full Text Available BACKGROUND: Varanidae is a clade of tiny (600 mm PCL lizards first appearing in the Cretaceous. True monitor lizards (Varanus are known from diagnostic remains beginning in the early Miocene (Varanus rusingensis, although extremely fragmentary remains have been suggested as indicating earlier Varanus. The paleobiogeographic history of Varanus and timing for origin of its gigantism remain uncertain. METHODOLOGY/PRINCIPAL FINDINGS: A new Varanus from the Mytilini Formation (Turolian, Miocene of Samos, Greece is described. The holotype consists of a partial skull roof, right side of a braincase, partial posterior mandible, fragment of clavicle, and parts of six vertebrae. A cladistic analysis including 83 taxa coded for 5733 molecular and 489 morphological characters (71 previously unincluded demonstrates that the new fossil is a nested member of an otherwise exclusively East Asian Varanus clade. The new species is the earliest-known giant (>600 mm PCL terrestrial lizard. Importantly, this species co-existed with a diverse continental mammalian fauna. CONCLUSIONS/SIGNIFICANCE: The new monitor is larger (longer than 99% of known fossil and living lizards. Varanus includes, by far, the largest limbed squamates today. The only extant non-snake squamates that approach monitors in maximum size are the glass-snake Pseudopus and the worm-lizard Amphisbaena. Mosasauroids were larger, but exclusively marine, and occurred only during the Late Cretaceous. Large, extant, non-Varanus, lizards are limbless and/or largely isolated from mammalian competitors. By contrast, our new Varanus achieved gigantism in a continental environment populated by diverse eutherian mammal competitors.

  20. Spontaneous magnetic alignment behaviour in free-living lizards

    Science.gov (United States)

    Diego-Rasilla, Francisco J.; Pérez-Mellado, Valentín; Pérez-Cembranos, Ana

    2017-04-01

    Several species of vertebrates exhibit spontaneous longitudinal body axis alignment relative to the Earth's magnetic field (i.e., magnetic alignment) while they are performing different behavioural tasks. Since magnetoreception is still not fully understood, studying magnetic alignment provides evidence for magnetoreception and broadens current knowledge of magnetic sense in animals. Furthermore, magnetic alignment widens the roles of magnetic sensitivity in animals and may contribute to shed new light on magnetoreception. In this context, spontaneous alignment in two species of lacertid lizards ( Podarcis muralis and Podarcis lilfordi) during basking periods was monitored. Alignments in 255 P. muralis and 456 P. lilfordi were measured over a 5-year period. The possible influence of the sun's position (i.e., altitude and azimuth) and geomagnetic field values corresponding to the moment in which a particular lizard was observed on lizards' body axis orientation was evaluated. Both species exhibited a highly significant bimodal orientation along the north-northeast and south-southwest magnetic axis. The evidence from this study suggests that free-living lacertid lizards exhibit magnetic alignment behaviour, since their body alignments cannot be explained by an effect of the sun's position. On the contrary, lizard orientations were significantly correlated with geomagnetic field values at the time of each observation. We suggest that this behaviour might provide lizards with a constant directional reference while they are sun basking. This directional reference might improve their mental map of space to accomplish efficient escape behaviour. This study is the first to provide spontaneous magnetic alignment behaviour in free-living reptiles.

  1. Tail-assisted pitch control in lizards, robots and dinosaurs.

    Science.gov (United States)

    Libby, Thomas; Moore, Talia Y; Chang-Siu, Evan; Li, Deborah; Cohen, Daniel J; Jusufi, Ardian; Full, Robert J

    2012-01-04

    In 1969, a palaeontologist proposed that theropod dinosaurs used their tails as dynamic stabilizers during rapid or irregular movements, contributing to their depiction as active and agile predators. Since then the inertia of swinging appendages has been implicated in stabilizing human walking, aiding acrobatic manoeuvres by primates and rodents, and enabling cats to balance on branches. Recent studies on geckos suggest that active tail stabilization occurs during climbing, righting and gliding. By contrast, studies on the effect of lizard tail loss show evidence of a decrease, an increase or no change in performance. Application of a control-theoretic framework could advance our general understanding of inertial appendage use in locomotion. Here we report that lizards control the swing of their tails in a measured manner to redirect angular momentum from their bodies to their tails, stabilizing body attitude in the sagittal plane. We video-recorded Red-Headed Agama lizards (Agama agama) leaping towards a vertical surface by first vaulting onto an obstacle with variable traction to induce a range of perturbations in body angular momentum. To examine a known controlled tail response, we built a lizard-sized robot with an active tail that used sensory feedback to stabilize pitch as it drove off a ramp. Our dynamics model revealed that a body swinging its tail experienced less rotation than a body with a rigid tail, a passively compliant tail or no tail. To compare a range of tails, we calculated tail effectiveness as the amount of tailless body rotation a tail could stabilize. A model Velociraptor mongoliensis supported the initial tail stabilization hypothesis, showing as it did a greater tail effectiveness than the Agama lizards. Leaping lizards show that inertial control of body attitude can advance our understanding of appendage evolution and provide biological inspiration for the next generation of manoeuvrable search-and-rescue robots.

  2. Spatial patterns in the abundance of the coastal horned lizard

    Science.gov (United States)

    Fisher, Robert N.; Suarez, Andrew V.; Case, Ted J.

    2002-01-01

    Coastal horned lizards (   Phrynosoma coronatum) have undergone severe declines in southern California and are a candidate species for state and federal listing under the Endangered Species Act. Quantitative data on their habitat use, abundance, and distribution are lacking, however. We investigated the determinants of abundance for coastal horned lizards at multiple spatial scales throughout southern California. Specifically, we estimated lizard distribution and abundance by establishing 256 pitfall trap arrays clustered within 21 sites across four counties. These arrays were sampled bimonthly for 2–3 years. At each array we measured 26 “local” site descriptors and averaged these values with other “regional” measures to determine site characteristics. Our analyses were successful at identifying factors within and among sites correlated with the presence and abundance of coastal horned lizards. These factors included the absence of the invasive Argentine ant (  Linepithema humile) (and presence of native ant species eaten by the lizards), the presence of chaparral community plants, and the presence of sandy substrates. At a regional scale the relative abundance of Argentine ants was correlated with the relative amount of developed edge around a site. There was no evidence for spatial autocorrelation, even at the scale of the arrays within sites, suggesting that the determinants of the presence or absence and abundance of horned lizard can vary over relatively small spatial scales ( hundreds of meters). Our results suggest that a gap-type approach may miss some of the fine-scale determinants of species abundance in fragmented habitats.

  3. Sand hazards on tourist beaches.

    Science.gov (United States)

    Heggie, Travis W

    2013-01-01

    Visiting the beach is a popular tourist activity worldwide. Unfortunately, the beach environment is abundant with hazards and potential danger to the unsuspecting tourist. While the traditional focus of beach safety has been water safety oriented, there is growing concern about the risks posed by the sand environment on beaches. This study reports on the death and near death experience of eight tourists in the collapse of sand holes, sand dunes, and sand tunnels. Each incident occurred suddenly and the complete burial in sand directly contributed to the victims injury or death in each case report.

  4. Modifying Directionality through Auditory System Scaling in a Robotic Lizard

    DEFF Research Database (Denmark)

    Shaikh, Danish; Hallam, John; Christensen-Dalsgaard, Jakob

    2010-01-01

    The peripheral auditory system of a lizard is strongly directional. This directionality is created by acoustical coupling of the two eardrums and is strongly dependent on characteristics of the middle ear, such as interaural distance, resonance frequency of the middle ear cavity and of the tympanum....... Therefore, directionality should be strongly influenced by their scaling. In the present study, we have exploited an FPGA–based mobile robot based on a model of the lizard ear to investigate the influence of scaling on the directional response, in terms of the robot’s performance in a phonotaxis task...

  5. PROCESSING OF MONAZITE SAND

    Science.gov (United States)

    Calkins, G.D.; Bohlmann, E.G.

    1957-12-01

    A process for the recovery of thorium, uranium, and rare earths from monazite sands is presented. The sands are first digested and dissolved in concentrated NaOH, and the solution is then diluted causing precipitation of uranium, thorium and rare earth hydroxides. The precipitate is collected and dissolved in HCl, and the pH of this solution is adjusted to about 6, precipitating the hydroxides of thorium and uranium but leaving the rare earths in solution. The rare earths are then separated from the solution by precipitation at a still higher pH. The thorium and uranium containing precipitate is redissolved in HNO/sub 3/ and the two elements are separated by extraction into tributyl phosphate and back extraction with a weakly acidic solution to remove the thorium.

  6. Moving sand dunes

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    In several desert areas, the slow motion of sand dunes can be a challenge for modern human activities and a threat for the survival of ancient places or archaeological sites. However, several methods exist for surveying the dune fields and estimate their migration rate. Among these methods, the use of satellite images, in particular of those freely available on the World Wide Web, is a convenient resource for the planning of future human settlements and activities.

  7. Determining the nature of orbits in a three-dimensional galaxy model hosting a BL Lacertae object

    CERN Document Server

    Zotos, Euaggelos E

    2014-01-01

    A three-dimensional dynamical model for a galaxy hosting a BL Lacertae object is constructed. The model consists of a logarithmic potential representing an elliptical host galaxy with a bulge of radius $c_b$ and a dense massive nucleus. Using numerical experiments, we try to distinguish between regular and chaotic motion in both 2D and 3D system. In particular, we investigate how the basic parameters of our model, such as the mass of the nucleus, the internal perturbation and the flattening parameters influence the amount and the degree of chaos. Interesting correlations are presented for both 2D and 3D dynamical models. Our numerical results are explained and supported using elementary theoretical arguments and analytical calculations. Of particular interest, is the local integral of motion which have been found to exist in the vicinity of stable periodic points. The obtained numerical outcomes of the present research, are linked and also compared with several data derived from observations.

  8. Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification

    CERN Document Server

    Handler, G; Rodríguez, E; Uytterhoeven, K; Amado, P J; Dorokhova, T N; Dorokhov, N I; Poretti, E; Sareyan, J P; Parrao, L; Lorenz, D; Zsuffa, D; Drummond, R; Daszynska-Daszkiewicz, J; Verhoelst, T; De Ridder, J; Acke, B; Bourge, P O; Movchan, A I; Garrido, R; Paparo, M; Sahin, T; Antoci, V; Udovichenko, S N; Csorba, K; Crowe, R; Berkey, B; Stewart, S; Terry, D; Mkrtichian, D E; Aerts, C

    2006-01-01

    We report a multisite photometric campaign for the Beta Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with 9 telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Eleven of those correspond to independent pulsation modes, and the remainder are combination frequencies. We find some slow aperiodic variability such as that seemingly present in several Beta Cephei stars. We perform mode identification from our colour photometry, derive the spherical degree l for the five strongest modes unambiguously and provide constraints on l for the weaker modes. We find a mixture of modes of 0 <= l <= 4. In particular, we prove that the previously suspected rotationally split triplet within the modes of 12 Lac consists of modes of different l; their equal frequency splitting must thus be accidental. One of the periodic signals we detected in the light c...

  9. Booming Sand Dunes

    Science.gov (United States)

    Vriend, Nathalie

    "Booming" sand dunes are able to produce low-frequency sound that resembles a pure note from a music instrument. The sound has a dominant audible frequency (70-105 Hz) and several higher harmonics and may be heard from far distances away. A natural or induced avalanche from a slip face of the booming dune triggers the emission that may last for several minutes. There are various references in travel literature to the phenomenon, but to date no scientific explanation covered all field observations. This thesis introduces a new physical model that describes the phenomenon of booming dunes. The waveguide model explains the selection of the booming frequency and the amplification of the sound in terms of constructive interference in a confined geometry. The frequency of the booming is a direct function of the dimensions and velocities in the waveguide. The higher harmonics are related to the higher modes of propagation in the waveguide. The experimental validation includes quantitative field research at the booming dunes of the Mojave Desert and Death Valley National Park. Microphone and geophone recordings of the acoustic and seismic emission show a variation of booming frequency in space and time. The analysis of the sensor data quantifies wave propagation characteristics such as speed, dispersion, and nonlinear effects and allows the distinction between the source mechanism of the booming and the booming itself. The migration of sand dunes results from a complicated interplay between dune building, wind regime, and precipitation. The morphological and morphodynamical characteristics of two field locations are analyzed with various geophysical techniques. Ground-penetrating radar images the subsurface structure of the dunes and reveal a natural, internal layering that is directly related to the history of dune migration. The seismic velocity increases abruptly with depth and gradually increases with downhill position due to compaction. Sand sampling shows local

  10. Evolution of Anolis lizard dewlap diversity.

    Directory of Open Access Journals (Sweden)

    Kirsten E Nicholson

    Full Text Available BACKGROUND: The dewlaps of Anolis lizards provide a classic example of a complex signaling system whose function and evolution is poorly understood. Dewlaps are flaps of skin beneath the chin that are extended and combined with head and body movements for visual signals and displays. They exhibit extensive morphological variation and are one of two cladistic features uniting anoles, yet little is known regarding their function and evolution. We quantified the diversity of anole dewlaps, investigated whether dewlap morphology was informative regarding phylogenetic relationships, and tested two separate hypotheses: (A similar Anolis habitat specialists possess similar dewlap configurations (Ecomorph Convergence hypothesis, and (B sympatric species differ in their dewlap morphologies to a greater extent than expected by chance (Species Recognition hypothesis. METHODOLOGY/PRINCIPAL FINDINGS: We found that dewlap configurations (sizes, patterns and colors exhibit substantial diversity, but that most are easily categorized into six patterns that incorporate one to three of 13 recognizable colors. Dewlap morphology is not phylogenetically informative and, like other features of anoles, exhibits convergence in configurations. We found no support for the Ecomorph Convergence hypothesis; species using the same structural habitat were no more similar in dewlap configuration than expected by chance. With one exception, all sympatric species in four communities differ in dewlap configuration. However, this provides only weak support for the Species Recognition hypothesis because, due to the great diversity in dewlap configurations observed across each island, few cases of sympatric species with identical dewlaps would be expected to co-occur by chance alone. CONCLUSIONS/SIGNIFICANCE: Despite previous thought, most dewlaps exhibit easily characterizable patterns and colorations. Nevertheless, dewlap variation is extensive and explanations for the origin and

  11. Sediment mathematical model for sand ridges and sand waves

    Institute of Scientific and Technical Information of China (English)

    LI Daming; WANG Xiao; WANG Xin; LI Yangyang

    2016-01-01

    A new theoretical model is formulated to describe internal movement mechanisms of the sand ridges and sand waves based on the momentum equation of a solid-liquid two-phase flow under a shear flow. Coupling this equation with two-dimensional shallow water equations and wave reflection-diffraction equation of mild slope, a two-dimensional coupling model is established and a validation is carried out by observed hydrogeology, tides, waves and sediment. The numerical results are compared with available observations. Satisfactory agreements are achieved. This coupling model is then applied to the Dongfang 1-1 Gas Field area to quantitatively predict the movement and evolution of submarine sand ridges and sand waves. As a result, it is found that the sand ridges and sand waves movement distance increases year by year, but the development trend is stable.

  12. Learning to Localize Sound with a Lizard Ear Model

    DEFF Research Database (Denmark)

    Shaikh, Danish; Hallam, John; Christensen-Dalsgaard, Jakob

    The peripheral auditory system of a lizard is strongly directional in the azimuth plane due to the acoustical coupling of the animal's two eardrums. This feature by itself is insufficient to accurately localize sound as the extracted directional information cannot be directly mapped to the sound...

  13. Structure and function of the hearts of lizards and snakes.

    Science.gov (United States)

    Jensen, Bjarke; Moorman, Antoon F M; Wang, Tobias

    2014-05-01

    With approximately 7000 species, snakes and lizards, collectively known as squamates, are by far the most species-rich group of reptiles. It was from reptile-like ancestors that mammals and birds evolved and squamates can be viewed as phylogenetically positioned between them and fishes. Hence, their hearts have been studied for more than a century yielding insights into the group itself and into the independent evolution of the fully divided four-chambered hearts of mammals and birds. Structurally the heart is complex and debates persist on rudimentary issues such as identifying structures critical to understanding ventricle function. In seeking to resolve these controversies we have generated three-dimensional (3D) models in portable digital format (pdf) of the anaconda and anole lizard hearts ('typical' squamate hearts) and the uniquely specialized python heart with comprehensive annotations of structures and cavities. We review the anatomy and physiology of squamate hearts in general and emphasize the unique features of pythonid and varanid lizard hearts that endow them with mammal-like blood pressures. Excluding pythons and varanid lizards it is concluded that the squamate heart has a highly consistent design including a disproportionately large right side (systemic venous) probably due to prevailing pulmonary bypass (intraventricular shunting). Unfortunately, investigations on rudimentary features are sparse. We therefore point out gaps in our knowledge, such as the size and functional importance of the coronary vasculature and of the first cardiac chamber, the sinus venosus, and highlight areas with implications for vertebrate cardiac evolution.

  14. The auditory brainstem response in two lizard species

    DEFF Research Database (Denmark)

    Brittan-Powell, Elizabeth F; Christensen-Dalsgaard, Jakob; Tang, Yezhong

    2010-01-01

    Although lizards have highly sensitive ears, it is difficult to condition them to sound, making standard psychophysical assays of hearing sensitivity impractical. This paper describes non-invasive measurements of the auditory brainstem response (ABR) in both Tokay geckos (Gekko gecko; nocturnal...... in most bird species....

  15. Technique for Measuring Speed and Visual Motion Sensitivity in Lizards

    Science.gov (United States)

    Woo, Kevin L.; Burke, Darren

    2008-01-01

    Testing sensory characteristics on herpetological species has been difficult due to a range of properties related to physiology, responsiveness, performance ability, and the type of reinforcer used. Using the Jacky lizard as a model, we outline a successfully established procedure in which to test the visual sensitivity to motion characteristics.…

  16. Ecology and behavior of the Jamaican Lizard Cuckoo

    NARCIS (Netherlands)

    Cruz, Alexander

    1975-01-01

    On Jamaica many of the endemic land birds are poorly known from an ecological and behavioral standpoint. Therefore, the following information on the food, foraging behavior, and habitats of the Jamaican Lizard Cuckoo Saurothera vetula), obtained while engaged in other studies, should be helpful in t

  17. Comparative morphology of Liolaemus lizards precloacal glands

    Directory of Open Access Journals (Sweden)

    Soledad Valdecantos

    2014-12-01

    Full Text Available Liolaemid lizards and amphisbaenids have precloacal pores in the anterior border of the cloaca, where epidermal glands drain and expel pheromonal secretions. Precloacal glands occur usually only in males, but in those few species where both sexes have precloacal glands, these are larger in males. Only the morphology and/or histology of precloacal glands of amphisbaenids have been described, and it is unknown whether in lizards these glands differ across ages, sexes and/or species, and if the lack of pores is associated with a lack of glands. We investigated for the first time the morphology and histology of lizard precloacal glands, by studying three Liolaemus species that differ in the presence of pores in their cloaca: L. irregularis, in which adults and juveniles of both sexes have pores; L. poecilochromus, in which only adult males have pores, and L. neuquensis, in which the adults of both sexes lack pores. Results show that the number of pores varies among species and sexes, but not between ages of a species. Adults, but not juveniles, of L. irregularis have sexual dimorphism in pore sizes; these are larger in males than in females. In addition, pores are larger in adult males of L. irregularis than in L. poecilochromus. Glands are tubuloalveolar with holocrine secretion, having similar structure across individuals, although adult males have larger glands than females and juveniles. Finally, the structure of Liolaemus precloacal glands is very similar to those of the amphisbaenid precloacal glands and the femoral glands of other lizard species.

  18. Microhabitat choice in island lizards enhances camouflage against avian predators.

    Science.gov (United States)

    Marshall, Kate L A; Philpot, Kate E; Stevens, Martin

    2016-01-25

    Camouflage can often be enhanced by genetic adaptation to different local environments. However, it is less clear how individual behaviour improves camouflage effectiveness. We investigated whether individual Aegean wall lizards (Podarcis erhardii) inhabiting different islands rest on backgrounds that improve camouflage against avian predators. In free-ranging lizards, we found that dorsal regions were better matched against chosen backgrounds than against other backgrounds on the same island. This suggests that P. erhardii make background choices that heighten individual-specific concealment. In achromatic camouflage, this effect was more evident in females and was less distinct in an island population with lower predation risk. This suggests that behavioural enhancement of camouflage may be more important in females than in sexually competing males and related to predation risk. However, in an arena experiment, lizards did not choose the background that improved camouflage, most likely due to the artificial conditions. Overall, our results provide evidence that behavioural preferences for substrates can enhance individual camouflage of lizards in natural microhabitats, and that such adaptations may be sexually dimorphic and dependent on local environments. This research emphasizes the importance of considering links between ecology, behaviour, and appearance in studies of intraspecific colour variation and local adaptation.

  19. Ecology and behavior of the Jamaican Lizard Cuckoo

    NARCIS (Netherlands)

    Cruz, Alexander

    1975-01-01

    On Jamaica many of the endemic land birds are poorly known from an ecological and behavioral standpoint. Therefore, the following information on the food, foraging behavior, and habitats of the Jamaican Lizard Cuckoo Saurothera vetula), obtained while engaged in other studies, should be helpful in

  20. A review of diagnostic imaging of snakes and lizards.

    Science.gov (United States)

    Banzato, T; Hellebuyck, T; Van Caelenberg, A; Saunders, J H; Zotti, A

    2013-07-13

    Snakes and lizards are considered 'stoic' animals and often show only non-specific signs of illness. Consequently, diagnostic imaging--along with clinical examination and laboratory tests--is gaining importance in making a final diagnosis and establishing a correct therapy. The large number of captive snake and lizard species commonly kept as pets, together with the high inter- and intraspecific morphological variability that is innate in these animals, make the analysis of diagnostic images challenging for the veterinary practitioner. Moreover, a thorough knowledge of the anatomy, physiology and pathology of the species that are the object of clinical investigation is mandatory for the correct interpretation of diagnostic images. Despite the large amount of clinical and scientific work carried out in the past two decades, the radiographic features of snakes and lizards have not undergone systematic description, and therefore veterinarians often have to rely mostly on anatomical studies rather than radiological literature. The aim of this paper is to review the most commonly used diagnostic imaging modalities, as well as to provide an overview of the available international original studies and scientific reviews describing the normal and pathological imaging features in snakes and lizards.

  1. Ecology and behavior of the Jamaican Lizard Cuckoo

    NARCIS (Netherlands)

    Cruz, Alexander

    1975-01-01

    On Jamaica many of the endemic land birds are poorly known from an ecological and behavioral standpoint. Therefore, the following information on the food, foraging behavior, and habitats of the Jamaican Lizard Cuckoo Saurothera vetula), obtained while engaged in other studies, should be helpful in t

  2. Lizard\\'s fauna of the Sabzevar with particular emphasis on the syntopic lizard and presentation of a framework for reptile distribution of Iran

    Directory of Open Access Journals (Sweden)

    Masoud Yousefi

    2013-11-01

    Full Text Available Sabzevar is one of the most biologically diverse regions in northeast Iran, with the area of 19500 km2 and an elevational of 950-2977 m. During a long term study of lizards in this area which lasted 3 years, 21 species and subspecies of lizards belonging to 13 genera and 5 families were collected, recognized and reported. The families Anguidae, Eublepharidae and Uromastycidae were not represented in the area. The genus Eremias with 6 species was the most diverse genus in Sabzevar district. More emphasis was given to the syntopic reptiles. This showed that Trapelus agailis with having 18 syntopic species and Cyrtopodion caspium with no syntopic species were in the extreme sides. Due to our little knowledge on the distribution of reptiles in Iran, we designed a framework for providing a reptile's distribution map in Iran.

  3. Ondas de choque em jatos de quasares e objetos BL Lacertae

    Science.gov (United States)

    Melo, F. E.; Botti, L. C. L.

    2003-08-01

    Este trabalho é parte de um projeto que vem sendo realizado há dois anos no CRAAM, cujos objetivos principais são analisar e aplicar um modelo generalizado de ondas de choque em jatos relativísticos de plasma, presentes em quasares e objetos BL Lacertae, para explicar a variabilidade observada nestes objetos. O método consiste em uma decomposição de curvas de luz em séries de explosões similares, em várias freqüências, baseando-se em uma evolução espectro-temporal média das explosões. A partir da evolução média, um ajuste de cada explosão é feito com base em equações empíricas, modificando-se apenas parâmetros específicos de cada explosão. Inicialmente o modelo foi aplicado ajustando-se as curvas de luz a explosões delineadas por uma evolução do choque em três estágios, segundo a predominância do processo de emissão: síncrotron, Compton e adiabático. Entretanto, nesta nova fase de projeto, visando uma parametrização mais concisa, uma otimização do algoritmo de ajuste e uma convergência mais rápida, a formulação para cada evento foi assumida com uma evolução em apenas dois estágios: subida e descida. Isto possibilitou uma ótima delineação das curvas de luz das fontes OV236, OJ287, 3C273 e BL Lac, entre 1980 e 2000, nas freqüências 4.8, 8.0, 14.5 e 22 GHz, utilizando-se dados do Observatório da Universidade de Michigan, do Observatório do Itapetinga (Atibaia SP) e do Observatório Metsähovi. Como conclusões importantes, verificou-se que: os parâmetros ajustados descrevem o comportamento do jato; os valores do índice que descreve a expansão do jato sugerem que o mesmo se expande de uma forma não-cônica; o campo magnético é turbulento atrás da frente de choque; e as peculiaridades das explosões são devidas à influência de grandezas tais como o coeficiente da distribuição espectral de energia dos elétrons, a intensidade de campo magnético e o fator de feixe Doppler, no início do choque.

  4. Distinct patterns of desynchronized limb regression in malagasy scincine lizards (squamata, scincidae.

    Directory of Open Access Journals (Sweden)

    Aurélien Miralles

    Full Text Available Scincine lizards in Madagascar form an endemic clade of about 60 species exhibiting a variety of ecomorphological adaptations. Several subclades have adapted to burrowing and convergently regressed their limbs and eyes, resulting in a variety of partial and completely limbless morphologies among extant taxa. However, patterns of limb regression in these taxa have not been studied in detail. Here we fill this gap in knowledge by providing a phylogenetic analysis of DNA sequences of three mitochondrial and four nuclear gene fragments in an extended sampling of Malagasy skinks, and microtomographic analyses of osteology of various burrowing taxa adapted to sand substrate. Based on our data we propose to (i consider Sirenoscincus Sakata & Hikida, 2003, as junior synonym of Voeltzkowia Boettger, 1893; (ii resurrect the genus name Grandidierina Mocquard, 1894, for four species previously included in Voeltzkowia; and (iii consider Androngo Brygoo, 1982, as junior synonym of Pygomeles Grandidier, 1867. By supporting the clade consisting of the limbless Voeltzkowia mira and the forelimb-only taxa V. mobydick and V. yamagishii, our data indicate that full regression of limbs and eyes occurred in parallel twice in the genus Voeltzkowia (as hitherto defined that we consider as a sand-swimming ecomorph: in the Voeltzkowia clade sensu stricto the regression first affected the hindlimbs and subsequently the forelimbs, whereas the Grandidierina clade first regressed the forelimbs and subsequently the hindlimbs following the pattern prevalent in squamates. Timetree reconstructions for the Malagasy Scincidae contain a substantial amount of uncertainty due to the absence of suitable primary fossil calibrations. However, our preliminary reconstructions suggest rapid limb regression in Malagasy scincids with an estimated maximal duration of 6 MYr for a complete regression in Paracontias, and 4 and 8 MYr respectively for complete regression of forelimbs in

  5. Compressive behavior of fine sand.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  6. Sand dollar sites orogenesis

    Science.gov (United States)

    Amos, Dee

    2013-04-01

    The determinology of the humble sand dollars habitat changing from inception to the drastic evolution of the zone to that of present day. Into the cauldron along the southern Californian 'ring of fire' lithosphere are evidence of geosynclinals areas, metasedimentary rock formations and hydrothermal activity. The explanation begins with 'Theia' and the Moon's formation, battles with cometary impacts, glacial ages, epochs with evolutionary bottlenecks and plate tectonics. Fully illustrated the lecture includes localised diagrams and figures with actual subject photographic examples of plutonic, granitic, jade and peridodite. Finally, the origins of the materials used in the lecture are revealed for prosecution by future students and the enjoyment of interested parties in general.

  7. Sand Storms Trigger Alarm

    Institute of Scientific and Technical Information of China (English)

    LI LI

    2010-01-01

    @@ After an unusually humid winter with at least 10 snowfalls in Beijing, a severe andstorm blown by strong winds bringing with it thousands of tons of desert sand took many residents of the city by surprise.On the morning of March 20, Beijingers woke up to see clouds of yellow dust in the air and a sky that was an ominous orange in color.The loose soil and dust that had traveled htmdreds of miles from deserts in Mongolia and China's northwest blanketed Beijing's streets, covering parked vehicles, bikes, roofs and even plant life,as well as making its way into people's homes.

  8. Fortune Cookie Sand Dunes

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-432, 25 July 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of small barchan sand dunes in the north polar region near 71.7oN, 51.3oW. Some of them are shaped like fortune cookies. The message these dunes provide: winds blow through this region from the lower right toward the upper left. The steep slip face slopes of these dunes, which point toward the upper left, indicate the wind direction. The scene is illuminated by sunlight from the upper right. The image is 3 km (1.9 mi) wide.

  9. The decoupling of abundance and species richness in lizard communities.

    Science.gov (United States)

    Nimmo, Dale G; James, Simon G; Kelly, Luke T; Watson, Simon J; Bennett, Andrew F

    2011-05-01

    1. Patterns of species richness often correlate strongly with measures of energy. The more individuals hypothesis (MIH) proposes that this relationship is facilitated by greater resources supporting larger populations, which are less likely to become extinct. Hence, the MIH predicts that community abundance and species richness will be positively related. 2. Recently, Buckley & Jetz (2010, Journal of Animal Ecology, 79, 358-365) documented a decoupling of community abundance and species richness in lizard communities in south-west United States, such that richer communities did not contain more individuals. They predicted, as a consequence of the mechanisms driving the decoupling, a more even distribution of species abundances in species-rich communities, evidenced by a positive relationship between species evenness and species richness. 3. We found a similar decoupling of the relationship between abundance and species richness for lizard communities in semi-arid south-eastern Australia. However, we note that a positive relationship between evenness and richness is expected because of the nature of the indices used. We illustrate this mathematically and empirically using data from both sets of lizard communities. When we used a measure of evenness, which is robust to species richness, there was no relationship between evenness and richness in either data set. 4. For lizard communities in both Australia and the United States, species dominance decreased as species richness increased. Further, with the iterative removal of the first, second and third most dominant species from each community, the relationship between abundance and species richness became increasingly more positive. 5. Our data support the contention that species richness in lizard communities is not directly related to the number of individuals an environment can support. We propose an alternative hypothesis regarding how the decoupling of abundance and richness is accommodated; namely, an inverse

  10. Functional and structural diversification of the Anguimorpha lizard venom system.

    Science.gov (United States)

    Fry, Bryan G; Winter, Kelly; Norman, Janette A; Roelants, Kim; Nabuurs, Rob J A; van Osch, Matthias J P; Teeuwisse, Wouter M; van der Weerd, Louise; McNaughtan, Judith E; Kwok, Hang Fai; Scheib, Holger; Greisman, Laura; Kochva, Elazar; Miller, Laurence J; Gao, Fan; Karas, John; Scanlon, Denis; Lin, Feng; Kuruppu, Sanjaya; Shaw, Chris; Wong, Lily; Hodgson, Wayne C

    2010-11-01

    Venom has only been recently discovered to be a basal trait of the Anguimorpha lizards. Consequently, very little is known about the timings of toxin recruitment events, venom protein molecular evolution, or even the relative physical diversifications of the venom system itself. A multidisciplinary approach was used to examine the evolution across the full taxonomical range of this ∼130 million-year-old clade. Analysis of cDNA libraries revealed complex venom transcriptomes. Most notably, three new cardioactive peptide toxin types were discovered (celestoxin, cholecystokinin, and YY peptides). The latter two represent additional examples of convergent use of genes in toxic arsenals, both having previously been documented as components of frog skin defensive chemical secretions. Two other novel venom gland-overexpressed modified versions of other protein frameworks were also recovered from the libraries (epididymal secretory protein and ribonuclease). Lectin, hyaluronidase, and veficolin toxin types were sequenced for the first time from lizard venoms and shown to be homologous to the snake venom forms. In contrast, phylogenetic analyses demonstrated that the lizard natriuretic peptide toxins were recruited independently of the form in snake venoms. The de novo evolution of helokinestatin peptide toxin encoding domains within the lizard venom natriuretic gene was revealed to be exclusive to the helodermatid/anguid subclade. New isoforms were sequenced for cysteine-rich secretory protein, kallikrein, and phospholipase A(2) toxins. Venom gland morphological analysis revealed extensive evolutionary tinkering. Anguid glands are characterized by thin capsules and mixed glands, serous at the bottom of the lobule and mucous toward the apex. Twice, independently this arrangement was segregated into specialized serous protein-secreting glands with thick capsules with the mucous lobules now distinct (Heloderma and the Lanthanotus/Varanus clade). The results obtained

  11. Functional and Structural Diversification of the Anguimorpha Lizard Venom System*

    Science.gov (United States)

    Fry, Bryan G.; Winter, Kelly; Norman, Janette A.; Roelants, Kim; Nabuurs, Rob J. A.; van Osch, Matthias J. P.; Teeuwisse, Wouter M.; van der Weerd, Louise; Mcnaughtan, Judith E.; Kwok, Hang Fai; Scheib, Holger; Greisman, Laura; Kochva, Elazar; Miller, Laurence J.; Gao, Fan; Karas, John; Scanlon, Denis; Lin, Feng; Kuruppu, Sanjaya; Shaw, Chris; Wong, Lily; Hodgson, Wayne C.

    2010-01-01

    Venom has only been recently discovered to be a basal trait of the Anguimorpha lizards. Consequently, very little is known about the timings of toxin recruitment events, venom protein molecular evolution, or even the relative physical diversifications of the venom system itself. A multidisciplinary approach was used to examine the evolution across the full taxonomical range of this ∼130 million-year-old clade. Analysis of cDNA libraries revealed complex venom transcriptomes. Most notably, three new cardioactive peptide toxin types were discovered (celestoxin, cholecystokinin, and YY peptides). The latter two represent additional examples of convergent use of genes in toxic arsenals, both having previously been documented as components of frog skin defensive chemical secretions. Two other novel venom gland-overexpressed modified versions of other protein frameworks were also recovered from the libraries (epididymal secretory protein and ribonuclease). Lectin, hyaluronidase, and veficolin toxin types were sequenced for the first time from lizard venoms and shown to be homologous to the snake venom forms. In contrast, phylogenetic analyses demonstrated that the lizard natriuretic peptide toxins were recruited independently of the form in snake venoms. The de novo evolution of helokinestatin peptide toxin encoding domains within the lizard venom natriuretic gene was revealed to be exclusive to the helodermatid/anguid subclade. New isoforms were sequenced for cysteine-rich secretory protein, kallikrein, and phospholipase A2 toxins. Venom gland morphological analysis revealed extensive evolutionary tinkering. Anguid glands are characterized by thin capsules and mixed glands, serous at the bottom of the lobule and mucous toward the apex. Twice, independently this arrangement was segregated into specialized serous protein-secreting glands with thick capsules with the mucous lobules now distinct (Heloderma and the Lanthanotus/Varanus clade). The results obtained highlight

  12. Condition-dependent chemosignals in reproductive behavior of lizards.

    Science.gov (United States)

    Martín, José; López, Pilar

    2015-02-01

    This article is part of a Special Issue "Chemosignals and Reproduction". Many lizards have diverse glands that produce chemosignals used in intraspecific communication and that can have reproductive consequences. For example, information in chemosignals of male lizards can be used in intrasexual competition to identify and assess the fighting potential or dominance status of rival males either indirectly through territorial scent-marks or during agonistic encounters. Moreover, females of several lizard species "prefer" to establish or spend more time on areas scent-marked by males with compounds signaling a better health or body condition or a higher genetic compatibility, which can have consequences for their mating success and inter-sexual selection processes. We review here recent studies that suggest that the information content of chemosignals of lizards may be reliable because several physiological and endocrine processes would regulate the proportions of chemical compounds available for gland secretions. Because chemosignals are produced by the organism or come from the diet, they should reflect physiological changes, such as different hormonal levels (e.g. testosterone or corticosterone) or different health states (e.g. parasitic infections, immune response), and reflect the quality of the diet of an individual. More importantly, some compounds that may function as chemosignals also have other important functions in the organism (e.g. as antioxidants or regulating the immune system), so there could be trade-offs between allocating these compounds to attending physiological needs or to produce costly sexual "chemical ornaments". All these factors may contribute to maintain chemosignals as condition-dependent sexual signals, which can inform conspecifics on the characteristics and state of the sender and allow making behavioral decisions with reproductive consequences. To understand the evolution of chemical secretions of lizards as sexual signals and their

  13. Particle Erosion Resistance of Bionic Samples Inspired from Skin Structure of Desert Lizard, Laudakin stoliczkana

    Institute of Scientific and Technical Information of China (English)

    He Huang; Yan Zhang; Luquan Ren

    2012-01-01

    In order to improve the particle erosion resistance of engineering surfaces,this paper proposed a bionic sample which is inspired from the skin structure of desert lizard,Laudakin stoliczkana.The bionic sample consists of a hard shell (aluminum) and a soft core (silicone rubber) which form a two-layer composite structure.The sand blast tests indicated that the bionic sample has better particle erosion resistance.In steady erosion period,the weight loss per unit time of the bionic sample is about 10% smaller than the contrast sample.The anti-erosion mechanism of the bionic sample was studied by single particle impact test.The results show that,after the impact,the kinetic energy of the particle is reduced by 56.5% on the bionic sample which is higher than that on the contrast sample (31.2%).That means the bionic sample can partly convert the kinetic energy of the particle into the deformation energy of the silicone rubber layer,thus the erosion is reduced.

  14. High frequency of pauses during intermittent locomotion of small South American gymnophthalmid lizards (Squamata, Gymnophthalmidae

    Directory of Open Access Journals (Sweden)

    Elizabeth Höfling

    2004-12-01

    Full Text Available We studied the locomotor behavior of two closely-related species of Gymnophthalmini lizards, Vanzosaura rubricauda and Procellosaurinus tetradactylus, that was imaged under laboratory conditions at a rate of 250 frames/s with a high-speed video camera (MotionScope PCI 1000 on four different substrates with increasing degrees of roughness (smooth perspex, cardboard, glued sand, and glued gravel. Vanzosaura rubricauda and P. tetradactylus are both characterized by intermittent locomotion, with pauses occurring with high frequency and having a short duration (from 1/10 to 1/3 s, and taking place in rhythmic locomotion in an organized fashion during all types ofgaits and on different substrates. The observed variations in duration and frequency of pauses suggest that in V. rubricauda mean pause duration is shorter and pause frequency is higher than in P. tetradactylus. The intermittent locomotion observed in V.rubricauda and P. tetradactylus imaging at 250 frames/s is probably of interest for neurobiologists. In the review of possible determinants, the phylogenetic relationships among the species of the tribe Gymnophthalmini are focused. Keywords: .

  15. A family of sand automata

    CERN Document Server

    Faulkner, Nicholas

    2012-01-01

    We study some dynamical properties of a family of two-dimensional cellular automata: those that arise from an underlying one dimensional sand automaton whose local rule is obtained using a latin square. We identify a simple sand automaton G whose local rule is algebraic, and classify this automaton as having equicontinuity points, but not being equicontinuous. We also show it is not surjective. We generalise some of these results to a wider class of sand automata.

  16. Dilatometric Characterization of Foundry Sands

    Directory of Open Access Journals (Sweden)

    M. Břuska

    2012-04-01

    Full Text Available The goal of this contribution is summary of physical – chemistry properties of usually used foundry silica and no – silica sands in Czech foundries. With the help of dilatometry analysis theoretical assumptions of influence of grain shape and size on dilatation value of sands were confirmed. Determined was the possibility of dilatometry analysis employment for preparing special (hybrid sands with lower and/or more linear character of dilatation.

  17. Triaxial tests in Fontainebleau sand

    DEFF Research Database (Denmark)

    Latini, Chiara; Zania, Varvara

    2016-01-01

    The purpose of this internal report is to examine the influence of relative density on the strength and deformation characteristics of Fontainebleau sand. Compression triaxial tests were performed on saturated sand samples with different densities and initial confining pressure. Note that the tes......The purpose of this internal report is to examine the influence of relative density on the strength and deformation characteristics of Fontainebleau sand. Compression triaxial tests were performed on saturated sand samples with different densities and initial confining pressure. Note...... that the testing procedure and the data processing were carried out according to the specifications of ETCS-F1.97....

  18. Ocular anatomy and retinal photoreceptors in a skink, the sleepy lizard (Tiliqua rugosa).

    Science.gov (United States)

    New, Shaun T D; Hemmi, Jan M; Kerr, Gregory D; Bull, C Michael

    2012-10-01

    The Australian sleepy lizard (Tiliqua rugosa) is a large day-active skink which occupies stable overlapping home ranges and maintains long-term monogamous relationships. Its behavioral ecology has been extensively studied, making the sleepy lizard an ideal model for investigation of the lizard visual system and its specializations, for which relatively little is known. We examine the morphology, density, and distribution of retinal photoreceptors and describe the anatomy of the sleepy lizard eye. The sleepy lizard retina is composed solely of photoreceptors containing oil droplets, a characteristic of cones. Two groups could be distinguished; single cones and double cones, consistent with morphological descriptions of photoreceptors in other diurnal lizards. Although all photoreceptors were cone-like in morphology, a subset of photoreceptors displayed immunoreactivity to rhodopsin-the visual pigment of rods. This finding suggests that while the morphological properties of rod photoreceptors have been lost, photopigment protein composition has been conserved during evolutionary history.

  19. Genetic Analysis of Multiple Paternity in an Endangered Ovoviviparous Lizard Shinisaurus crocodilurus

    Institute of Scientific and Technical Information of China (English)

    Huayuan HUANG; Dan LUO; Cong Guo; Zhuo TANG; Zhengjun WU; Jinping CHEN

    2015-01-01

    The crocodile lizard (Shinisaurus crocodilurus) is an ovoviviparous lizard belonging to a monotypic family that originated during the end of the quaternary ice age. A rare species in the wild, the crocodile lizard was listed in CITES Appendix Ⅱ . Knowledge of the reproductive biology and mating system of this species is important for designing conservation strategies and improving genetic variation. To investigate the paternity of the crocodile lizards and to interpret their reproductive behaviour, we collected saliva from females, potential fathers and offspring in a semi-natural enclosure experiment and analyzed the paternity of the crocodile lizard using 12 microsatellite genetic loci. The overall observed incidence of multiple paternity was 42.9% (6 of 14 clutches) and Fis was 0.089 ± 0.056. These results indicate that the primary mating mode of the crocodile lizard is that males are polygynous while with females are polyandrous, and there is multiple paternity among offspring of the same mother.

  20. Rock-dwelling lizards exhibit less sensitivity of sprint speed to increases in substrate rugosity.

    Science.gov (United States)

    Collins, Clint E; Self, Jessica D; Anderson, Roger A; McBrayer, Lance D

    2013-06-01

    Effectively moving across variable substrates is important to all terrestrial animals. The effects of substrates on lizard performance have ecological ramifications including the partitioning of habitat according to sprinting ability on different surfaces. This phenomenon is known as sprint sensitivity, or the decrease in sprint speed due to change in substrate. However, sprint sensitivity has been characterized only in arboreal Anolis lizards. Our study measured sensitivity to substrate rugosity among six lizard species that occupy rocky, sandy, and/or arboreal habitats. Lizards that use rocky habitats are less sensitive to changes in substrate rugosity, followed by arboreal lizards, and then by lizards that use sandy habitats. We infer from comparative phylogenetic analysis that forelimb, chest, and tail dimensions are important external morphological features related to sensitivity to changes in substrate rugosity.

  1. Increased metal concentrations in giant sungazer lizards (Smaug giganteus) from mining areas in South Africa.

    Science.gov (United States)

    McIntyre, Trevor; Whiting, Martin J

    2012-11-01

    Environmental contaminants from anthropogenic activity such as mining can have profound health effects on the animals living in adjacent areas. We investigated whether inorganic contaminants associated with gold-mining waste discharges were accumulated by a threatened species of lizard, Smaug giganteus, in South Africa. Lizards were sampled from two mining sites and two control sites. Blood samples from the most contaminated mining site had significantly greater concentrations of lithium, sodium, aluminum, sulfur, silicon, chromium, manganese, iron, nickel, copper, tungsten, and bismuth than the remaining sites. Contaminant concentrations were not significantly related to lizard body condition, although these relationships were consistently negative. The adult sex ratio of the population inhabiting the most contaminated site also deviated from an expected 1:1 ratio in favour of female lizards. We demonstrate that lizards at these mining sites contained high concentrations of heavy metals that may be imposing as yet poorly understood costs to these lizards.

  2. Segregating variation for temperature-dependent sex determination in a lizard

    OpenAIRE

    Rhen, T; Schroeder, A.; Sakata, J T; Huang, V.; Crews, D.

    2010-01-01

    Temperature-dependent sex determination (TSD) was first reported in 1966 in an African lizard. It has since been shown that TSD occurs in some fish, several lizards, tuataras, numerous turtles and all crocodilians. Extreme temperatures can also cause sex reversal in several amphibians and lizards with genotypic sex determination. Research in TSD species indicates that estrogen signaling is important for ovary development and that orthologs of mammalian genes have a function in gonad different...

  3. Are mountain habitats becoming more suitable for generalist than cold-adapted lizards thermoregulation?

    OpenAIRE

    Zaida Ortega; Abraham Mencía; Valentín Pérez-Mellado

    2016-01-01

    Mountain lizards are highly vulnerable to climate change, and the continuous warming of their habitats could be seriously threatening their survival. We aim to compare the thermal ecology and microhabitat selection of a mountain lizard, Iberolacerta galani, and a widely distributed lizard, Podarcis bocagei, in a montane area. Both species are currently in close syntopy in the study area, at 1,400 m above the sea level. We determined the precision, accuracy and effectiveness of thermoregulatio...

  4. New genus and species names for the Eocene lizard Cadurcogekko rugosus Augé, 2005.

    Science.gov (United States)

    Bolet, Arnau; Daza, Juan D; Augé, Marc; Bauer, Aaron M

    2015-07-10

    Cadurcogekko rugosus Augé, 2005 was described as a gekkotan lizard from the Eocene of France. A revision of the material has revealed that the holotype, a nearly complete dentary, actually belongs to a scincid lizard, for which we erect the new genus Gekkomimus. The rest of material originally referred to C. rugosus is of undoubted gekkotan nature and is included in the new species Cadurcogekko verus, with the exception of a partial left dentary belonging to the iguanid lizard Cadurciguana hoffstetteri.

  5. Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard

    National Research Council Canada - National Science Library

    Drakeley, Maximilian; Lapiedra, Oriol; Kolbe, Jason J

    2015-01-01

    .... We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines...

  6. Helminths of the Lizard Salvator merianae (Squamata, Teiidae) in the Caatinga, Northeastern Brazil.

    Science.gov (United States)

    Teixeira, A A M; Brito, S V; Teles, D A; Ribeiro, S C; Araujo-Filho, J A; Lima, V F; Pereira, A M A; Almeida, W O

    2017-01-01

    The lizard Salvator merianae is a widely distributed species in South America, occurring from southern Amazonia to the eastern Andes and northern Patagonia. Studies on the parasitic fauna of this lizard have revealed that it is a host for helminths in various Brazilian biomes. The present work provides new parasitological data on the gastrointestinal nematodes associated with the lizard S. merianae. Sixteen specimens were analyzed from nine different locations in a semi-arid region in northeastern Brazil. Five species of nematodes were identified. Oswaldofilaria petersi was first recorded as a parasite of the S. merianae, thus increasing the knowledge of the fauna of parasites that infect large Neotropical lizards.

  7. Advantages in exploring a new environment with the left eye in lizards.

    Science.gov (United States)

    Bonati, Beatrice; Csermely, Davide; Sovrano, Valeria Anna

    2013-07-01

    Lizards (Podarcis muralis) preferentially use the left eye during spatial exploration in a binocular condition. Here we allowed 44 adult wild lizards to explore an unknown maze for 20 min under a temporary monocular condition whilst recording their movements, particularly the direction of turns made whilst walking within the maze. Lizards with a patch on their right eye, i.e. using their left eye to monitor the environment, moved faster than lizards with a patch on their left eye when turning both leftward and rightward in a T-cross. Hence, right eye-patched lizards were faster than left eye-patched lizards also in turning right, although their right eye was covered. Thus, lizards that could use the left eye/right hemisphere to attend spatial cues appeared to have more control and to be more prompt in exploring the maze. In addition, female lizards with their left eye covered stopped very frequently when they reached crosses, showing a high level of indecision. Results confirm that P. muralis lizards using their left eye only in exploring a new environment react faster and more efficiently than those using the right eye only in exploration. Hence lateralisation of spatial stimuli mediated by the left eye/right hemisphere could provide an advantage to this species.

  8. A sand wave simulation model

    NARCIS (Netherlands)

    Nemeth, A.A.; Hulscher, S.J.M.H.; Damme, van R.M.J.

    2003-01-01

    Sand waves form a prominent regular pattern in the offshore seabeds of sandy shallow seas. A two dimensional vertical (2DV) flow and morphological numerical model describing the behaviour of these sand waves has been developed. The model contains the 2DV shallow water equations, with a free water su

  9. Regeneration of dredged sand waves

    NARCIS (Netherlands)

    Hulscher, Suzanne J.M.H.; Knaapen, Michiel; Scholl, Olaf; Scholl, O.; Trenteseaux., A.; Garlan, T.

    2000-01-01

    Sand waves form a wavy pattern in the offshore sandy seabed. Since their crests reduce the navigability, it is important to know their evolution. A simple model is presented to estimate the recovery of sand wave amplitudes. This model is partially based on the similarity with sea ripples and

  10. Namibia : triaxial test on sand

    DEFF Research Database (Denmark)

    Steenfelt, Jørgen S.; Jacobsen, Kim P.

    In connection with a harbour project the friction angle of a fine sand is required. On Friday 13 March 1998 the Danish Geotechnical Institute (DGI) delivered app. 2.5 kg sand for testing at the Geotechnical Engineering Laboratory, Aalborg University. The present Data Report summarises the results...

  11. Expression of phenotypic plasticity in hatchlings of the lizard Calotes versicolor (Squamata: Agamidae: influence of nest moisture

    Directory of Open Access Journals (Sweden)

    Bhagyashri A. Shanbhag

    2012-06-01

    Full Text Available Calotes versicolor breed from late May to early October. The breeding activity begins with the onset of the southwest monsoon. The eggs laid in early breeding season experience more wet conditions than those of the late breeding season. We studied the influence of nest moisture levels on the phenotypic traits of hatchlings by burying the eggs in 5-cm-deep sand nests with ~50%(wet nest or ~20% (relatively dry nest moisture to simulate nesting conditions of early and late breeding seasons. A group of eggs were subjected to standard laboratory incubation procedure in which eggs are half-buried in the moist sand and the other half exposed to air. Hatching time and hatchling body size varied with the treatment. The eggs from dry nests hatched later and hatchlings were the biggest but possessed least amount of residual yolk compared to those of 'wet nest' and also 'lab incubated' groups. In these hatchlings head and limb sizes were significantly larger than that of the other two groups. The findings show: (1 a developmental plasticity in the lizard, (2 that under low moist conditionslarger body size is preferred, and (3 that the trade-off between somatic growth of embryos and future energy reserves (residual yolk of hatchlings is influenced by the soil moisture in C. versicolor.

  12. 2010 oil sands performance report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    With the depletion of traditional energy resources and the rising demand for energy, oil sands have become an important energy resource for meeting energy needs. Oil sands are a mixture of water, sand, clay and bitumen which is recovered either through open pit mining or in situ drilling techniques. The bitumen is then converted into syncrude or sold to refineries for the production of gasoline, diesel or other products. Shell has oil sands operations in Alberta and the aim of this report is to present its 2010 performance in terms of CO2, water, tailings, land, and reclamation and engagement. This document covers several of Shell's operations in the Muskeg River and Jackpine mines, Scotford upgrader, Peace River, Orion, Seal, Cliffdale and Chipmunk. It provides useful information on Shell's oil sands performance to governments, environmental groups, First Nations, local communities and the public.

  13. Simulating reef response to sea-level rise at Lizard Island: A geospatial approach

    Science.gov (United States)

    Hamylton, S. M.; Leon, J. X.; Saunders, M. I.; Woodroffe, C. D.

    2014-10-01

    Sea-level rise will result in changes in water depth over coral reefs, which will influence reef platform growth as a result of carbonate production and accretion. This study simulates the pattern of reef response on the reefs around Lizard Island in the northern Great Barrier Reef. Two sea-level rise scenarios are considered to capture the range of likely projections: 0.5 m and 1.2 m above 1990 levels by 2100. Reef topography has been established through extensive bathymetric profiling, together with available data, including LiDAR, single beam bathymetry, multibeam swath bathymetry, LADS and digitised chart data. The reef benthic cover around Lizard Island has been classified using a high resolution WorldView-2 satellite image, which is calibrated and validated against a ground referencing dataset of 364 underwater video records of the reef benthic character. Accretion rates are parameterised using published hydrochemical measurements taken in-situ and rules are applied using Boolean logic to incorporate geomorphological transitions associated with different depth ranges, such as recolonisation of the reef flat when it becomes inundated as sea level rises. Simulations indicate a variable platform response to the different sea-level rise scenarios. For the 0.5 m rise, the shallower reef flats are gradually colonised by corals, enabling this active geomorphological zone to keep up with the lower rate of rise while the other sand dominated areas get progressively deeper. In the 1.2 m scenario, a similar pattern is evident for the first 30 years of rise, beyond which the whole reef platform begins to slowly drown. To provide insight on reef response to sea-level rise in other areas, simulation results of four different reef settings are discussed and compared at the southeast reef flat (barrier reef), Coconut Beach (fringing reef), Watson's Bay (leeward bay with coral patches) and Mangrove Beach (sheltered lagoonal embayment). The reef sites appear to accrete upwards

  14. Sand harm in taklimakan Desert highway and sand control

    Institute of Scientific and Technical Information of China (English)

    HANZhiwen; WANGTao; SUNQingwei; DONGZhibao; WANGXunming

    2003-01-01

    Reputed as a wonderful achievement of the world’s highway construction history,the Taklimakan Desert highway is nor facing serious sand drift encroachment problems due to its 447-km-long passage of sand sea consisting of crescent dunes,barchan chains,compound transverse dune ridges and complex megadunes.To solve some technical problems in the protection of the highway from sang drift encroachment,desert experts have been conducting the theoretical and applied studies on sand movement laws;causes,severities and time-space differentiation of sand drift damages;and control ways including mechanical,chemical and biological measures.In this paper the authors give an overall summry on the research contents and recent progress in the control of sand drift damages in China and hold that the theoretical researc results and practices in the prevention of sand drift encroachment on the cross-desert highway represnt a breakthrough and has an cpoch-making significance.Since the construction of protective forest along the cross-desert highway requires large amount of ground water,what will be its environmental consequence and whether it can effectively halt sand drift encroachment on the highway forever are the questions to be studied urgently.

  15. Technique for measuring speed and visual motion sensitivity in lizards

    Directory of Open Access Journals (Sweden)

    Darren Burke

    2008-01-01

    Full Text Available Testing sensory characteristics on herpetological species has been difficult due to a range of properties related to physiology, responsiveness, performance ability, and the type of reinforcer used. Using the Jacky lizard as a model, we outline a successfully established procedure in which to test the visual sensitivity to motion characteristics. We incorporated modifications to traditional operant paradigms by using three video playback systems to deliver random-dot kinematogram motion stimuli coupled with salient computer-animated secondary reinforcers representative of biologically important appetitive stimuli. This procedure has the capacity to test other visual aspects in lizards as well as other nonhuman species using video playback and computer-animation techniques as experimental tools.

  16. Colorful displays signal male quality in a tropical anole lizard

    Science.gov (United States)

    Cook, Ellee G.; Murphy, Troy G.; Johnson, Michele A.

    2013-10-01

    Parasites influence colorful ornaments and their behavioral display in many animal hosts. Because coloration and display behavior are often critical components of communication, variation in these traits may have important implications for individual fitness, yet it remains unclear whether such traits are signals of quality in many taxa. We investigated the association between ectoparasitic mite load and the color and behavioral use of the throat fan (dewlap) by male Anolis brevirostris lizards. We found that heavily parasitized lizards exhibited lower body condition, duller dewlaps, and less frequent dewlap displays than less parasitized individuals. Our results thus suggest that highly parasitized individuals invest less in both ornamental color and behavioral display of that color. Because the two components of the signal simultaneously provide information on male quality, this study provides novel support for the long-standing hypothesis that colorful traits may function as social or sexual signals in reptiles.

  17. Physiological ecology of frillneck lizards in a seasonal tropical environment.

    Science.gov (United States)

    Christian, Keith A; Griffiths, Anthony D; Bedford, Gavin S

    1996-04-01

    The frillneck lizard, Chlamydosaurus kingii, is a conspicuous component of the fauna of the wetdry tropics of northern Australia during the wet season, but it is rarely seen in the dry season. Previous studies have demonstrated that during the dry season the field metabolic rate (FMR) is only about one-quarter of the wet-season rate, and one factor involved in this seasonal drop is a change in the behavioural thermoregulation of the species such that lower body temperatures (T bs) are selected during dry-season days. Here we examine other factors that could be responsible for the seasonal change in FMR: standard metabolic rates (SMR) and activity. Samples from stomach flushing revealed that the lizards in the dry season continued to feed, but the volume of food was half as much as in the wet season. SMR in the laboratory was 30% less in the dry season. During the dry season, the energy expended by the lizards is 60.4 kJ kg(-1) day(-1) less than during the wet season. Combining laboratory and field data, we determined the relative contribution of the factors involved in this energy savings: 10% can be attributed to lower nighttime T b, 12% is attributable to lower daytime T b, 12% is attributable to decreased metabolism, and the remaining 66% is attributable to other activities (including e.g. locomotion, reproductive costs, digestion). Calculations indicate that if FMR did not drop in the dry season the lizards would not survive on the observed food intake during this season. Seasonal analysis of blood plasma and urine indicated an accumulation of some electrolytes during the dry season suggesting modest levels of water stress.

  18. Climatic control of trophic interaction strength: the effect of lizards on spiders.

    Science.gov (United States)

    Spiller, David A; Schoener, Thomas W

    2008-01-01

    We investigated how temporal variation in rainfall influences the impact of lizards on spiders inhabiting small islands in Abaco, Bahamas. Annual censuses of web spiders were conducted on nine lizard islands and on eight no-lizard islands 1994-2003. Repeated-measures ANOVA showed that annual variation in spider density (time) and in the lizard effect on spider density (lizard x time) were both significant. Correlation coefficients between the lizard effect (ln ratio of no-lizard to lizard spider densities) and number of rainfall days were generally negative, and strengthened with length of the time period during which rainfall was measured prior to annual spider censuses. Spider density was also negatively correlated with rainfall days and strengthened with length of the prior time period. Longer time intervals included the hurricane season, suggesting that the strong negative correlations were linked to high rainfall years during which tropical storms impacted the region and reduced spider and lizard densities. Split-plot ANOVA showed that rainfall during the hurricane season had a significant effect on the lizard effect and on spider density. Results in this study are opposite to those found in our previous 10-year study (1981-1990) conducted in the Exuma Cays, a moderately xeric region of the Bahamas, where the relation between rainfall and the lizard effect on spider density was positive. Combined data from the Exuma and Abaco studies produce a unimodal relation between trophic interaction strength and rainfall; we suggest that the negative effect of storms associated with rainfall was paramount in the present study, whereas the positive bottom-up effect of rainfall prevailed in our previous study. We conclude that climatic variability has a major impact on the trophic interaction and suggest that a substantial change in precipitation in either direction may weaken the interaction significantly.

  19. Species composition, richness and nestedness of lizard assemblages from Restinga habitats along the brazilian coast.

    Science.gov (United States)

    Rocha, C F D; Vrcibradic, D; Kiefer, M C; Menezes, V A; Fontes, A F; Hatano, F H; Galdino, C A B; Bergallo, H G; Van Sluys, M

    2014-05-01

    Habitat fragmentation is well known to adversely affect species living in the remaining, relatively isolated, habitat patches, especially for those having small range size and low density. This negative effect has been critical in coastal resting habitats. We analysed the lizard composition and richness of restinga habitats in 16 restinga habitats encompassing three Brazilian states (Rio de Janeiro, Espírito Santo and Bahia) and more than 1500km of the Brazilian coast in order to evaluate if the loss of lizard species following habitat reduction occur in a nested pattern or at random, using the "Nestedness Temperature Calculator" to analyse the distribution pattern of lizard species among the restingas studied. We also estimated the potential capacity that each restinga has to maintain lizard species. Eleven lizard species were recorded in the restingas, although not all species occurred in all areas. The restinga with the richest lizard fauna was Guriri (eight species) whereas the restinga with the lowest richness was Praia do Sul (located at Ilha Grande, a large coastal island). Among the restingas analysed, Jurubatiba, Guriri, Maricá and Praia das Neves, were the most hospitable for lizards. The matrix community temperature of the lizard assemblages was 20.49° (= P lizard assemblages in the coastal restingas exhibited a considerable nested structure. The degree in which an area is hospitable for different assemblages could be used to suggest those with greater value of conservation. We concluded that lizard assemblages in coastal restingas occur at a considerable level of ordination in restinga habitats and that some restinga areas such as Jurubatiba, Guriri, Maricá and Praia das Neves are quite important to preserve lizard diversity of restinga environments.

  20. Species composition, richness and nestedness of lizard assemblages from Restinga habitats along the brazilian coast

    Directory of Open Access Journals (Sweden)

    CFD. Rocha

    Full Text Available Habitat fragmentation is well known to adversely affect species living in the remaining, relatively isolated, habitat patches, especially for those having small range size and low density. This negative effect has been critical in coastal resting habitats. We analysed the lizard composition and richness of restinga habitats in 16 restinga habitats encompassing three Brazilian states (Rio de Janeiro, Espírito Santo and Bahia and more than 1500km of the Brazilian coast in order to evaluate if the loss of lizard species following habitat reduction occur in a nested pattern or at random, using the “Nestedness Temperature Calculator” to analyse the distribution pattern of lizard species among the restingas studied. We also estimated the potential capacity that each restinga has to maintain lizard species. Eleven lizard species were recorded in the restingas, although not all species occurred in all areas. The restinga with the richest lizard fauna was Guriri (eight species whereas the restinga with the lowest richness was Praia do Sul (located at Ilha Grande, a large coastal island. Among the restingas analysed, Jurubatiba, Guriri, Maricá and Praia das Neves, were the most hospitable for lizards. The matrix community temperature of the lizard assemblages was 20.49° (= P <0.00001; 5000 randomisations; randomisation temperature = 51.45° ± 7.18° SD, indicating that lizard assemblages in the coastal restingas exhibited a considerable nested structure. The degree in which an area is hospitable for different assemblages could be used to suggest those with greater value of conservation. We concluded that lizard assemblages in coastal restingas occur at a considerable level of ordination in restinga habitats and that some restinga areas such as Jurubatiba, Guriri, Maricá and Praia das Neves are quite important to preserve lizard diversity of restinga environments.

  1. Eating lizards: a millenary habit evidenced by Paleoparasitology

    Directory of Open Access Journals (Sweden)

    Sianto Luciana

    2012-10-01

    Full Text Available Abstract Background Analyses of coprolites have contributed to the knowledge of diet as well as infectious diseases in ancient populations. Results of paleoparasitological studies showed that prehistoric groups were exposed to spurious and zoonotic parasites, especially food-related. Here we report the findings of a paleoparasitological study carried out in remote regions of Brazil’s Northeast. Findings Eggs of Pharyngodonidae (Nematoda, Oxyuroidea, a family of parasites of lizards and amphibians, were found in four human coprolites collected from three archaeological sites. In one of these, lizard scales were also found. Conclusions Through the finding of eggs of Pharyngodonidae in human coprolites and reptile scales in one of these, we have provided evidence that humans have consumed reptiles at least 10,000 years ago. This food habit persists to modern times in remote regions of Brazil’s Northeast. Although Pharyngodonidae species are not known to infect humans, the consumption of raw or undercooked meat from lizards and other reptiles may have led to transmission of a wide range of zoonotic agents to humans in the past.

  2. The first iguanian lizard from the Mesozoic of Africa

    Science.gov (United States)

    Daza, Juan D.; Simões, Tiago R.; Rage, Jean Claude

    2016-01-01

    The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along with Gueragama sulamericana (Late Cretaceous of Brazil). The new fossil supports the previously hypothesized widespread geographical distribution of acrodontans in Gondwana during the Mesozoic. Additionally, it provides the first fossil evidence of uromastycines in the Cretaceous, and the ancestry of acrodontan iguanians in Africa. PMID:27703708

  3. Fear no colors? Observer clothing color influences lizard escape behavior.

    Science.gov (United States)

    Putman, Breanna J; Drury, Jonathan P; Blumstein, Daniel T; Pauly, Gregory B

    2017-01-01

    Animals often view humans as predators, leading to alterations in their behavior. Even nuanced aspects of human activity like clothing color affect animal behavior, but we lack an understanding of when and where such effects will occur. The species confidence hypothesis posits that birds are attracted to colors found on their bodies and repelled by non-body colors. Here, we extend this hypothesis taxonomically and conceptually to test whether this pattern is applicable in a non-avian reptile and to suggest that species should respond less fearfully to their sexually-selected signaling color. Responses to clothing color could also be impacted by habituation to humans, so we examine whether behavior varied between areas with low and high human activity. We quantified the effects of four T-shirt colors on flight initiation distances (FID) and on the ease of capture in western fence lizards (Sceloporus occidentalis), and we accounted for detectability against the background environment. We found no differences in lizard behavior between sites. However, lizards tolerated the closest approaches and were most likely to be captured when approached with the T-shirt that resembled their sexually-selected signaling color. Because changes in individual behavior affect fitness, choice of clothing color by people, including tourists, hikers, and researchers, could impact wildlife populations and research outcomes.

  4. Morphology of the feeding system in agamid lizards: ecological correlates.

    Science.gov (United States)

    Herrel, A; Aerts, P; Fret, J; de Vree, F

    1999-04-01

    The interaction of organismal design with ecology, and its evolutionary development are the subject of many functional and ecomorphological studies. Many studies have shown that the morphology and mechanics of the masticatory apparatus in mammals are adapted to diet. To investigate the relations between diet and the morphological and physiological properties of the lizard jaw system, a detailed analysis of the structure of the jaw apparatus was undertaken in the insectivorous lizard Plocederma stellio and in closely related herbivorous lizards of the genus Uromastix. The morphological and physiological properties of the jaw system in P. stellio and U. aegyptius were studied by means of dissections, light microscopy, histochemical characterisations, and in vivo stimulation experiments. The skull of Uromastix seems to be built for forceful biting (high, short snout). Additionally, the pterygoid muscle is modified in P. stellio, resulting in an additional force component during static biting. Stimulation experiments indicate that jaw muscles in both species are fast, which is supported by histochemical stainings. However, the oxidative capacity of the jaw muscles is larger in Uromastix. Contraction characteristics and performance of the feeding system (force output) are clearly thermally dependent. We conclude that several characteristics of the jaw system (presence of extra portion of the pterygoid muscle, large oxidative capacity of jaw muscles) in Uromastix may be attributed to its herbivorous diet. Jaw muscles, however, are still faster than expected. This is presumably the result of trade-offs between the thermal characteristics of the jaw adductors and the herbivorous lifestyle of these animals.

  5. Behavioural flexibility and problem-solving in a tropical lizard.

    Science.gov (United States)

    Leal, Manuel; Powell, Brian J

    2012-02-23

    The role of behavioural flexibility in responding to new or changing environmental challenges is a central theme in cognitive ecology. Studies of behavioural flexibility have focused mostly on mammals and birds because theory predicts that behavioural flexibility is favoured in species or clades that exploit a diversity of habitats or food sources and/or have complex social structure, attributes not associated with ectothermic vertebrates. Here, we present the results of a series of experiments designed to test cognitive abilities across multiple cognitive modules in a tropical arboreal lizard: Anolis evermanni. This lizard shows behavioural flexibility across multiple cognitive tasks, including solving a novel motor task using multiple strategies and reversal learning, as well as rapid associative learning. This flexibility was unexpected because lizards are commonly believed to have limited cognitive abilities and highly stereotyped behaviour. Our findings indicate that the cognitive abilities of A. evermanni are comparable with those of some endothermic species that are recognized to be highly flexible, and strongly suggest a re-thinking of our understanding of the cognitive abilities of ectothermic tetrapods and of the factors favouring the evolution of behavioural flexibility.

  6. Evolution of extreme body size disparity in monitor lizards (Varanus).

    Science.gov (United States)

    Collar, David C; Schulte, James A; Losos, Jonathan B

    2011-09-01

    Many features of species' biology, including life history, physiology, morphology, and ecology are tightly linked to body size. Investigation into the causes of size divergence is therefore critical to understanding the factors shaping phenotypic diversity within clades. In this study, we examined size evolution in monitor lizards (Varanus), a clade that includes the largest extant lizard species, the Komodo dragon (V. komodoensis), as well as diminutive species that are nearly four orders of magnitude smaller in adult body mass. We demonstrate that the remarkable body size disparity of this clade is a consequence of different selective demands imposed by three major habitat use patterns-arboreality, terrestriality, and rock-dwelling. We reconstructed phylogenetic relationships and ancestral habitat use and applied model selection to determine that the best-fitting evolutionary models for species' adult size are those that infer oppositely directed adaptive evolution associated with terrestriality and rock-dwelling, with terrestrial lineages evolving extremely large size and rock-dwellers becoming very small. We also show that habitat use affects the evolution of several ecologically important morphological traits independently of body size divergence. These results suggest that habitat use exerts a strong, multidimensional influence on the evolution of morphological size and shape disparity in monitor lizards.

  7. Polyandry in dragon lizards: inbred paternal genotypes sire fewer offspring.

    Science.gov (United States)

    Frère, Celine H; Chandrasoma, Dani; Whiting, Martin J

    2015-04-01

    Multiple mating in female animals is something of a paradox because it can either be risky (e.g., higher probability of disease transmission, social costs) or provide substantial fitness benefits (e.g., genetic bet hedging whereby the likelihood of reproductive failure is lowered). The genetic relatedness of parental units, particularly in lizards, has rarely been studied in the wild. Here, we examined levels of multiple paternity in Australia's largest agamid lizard, the eastern water dragon (Intellagama lesueurii), and determined whether male reproductive success is best explained by its heterozygosity coefficient or the extent to which it is related to the mother. Female polyandry was the norm: 2/22 clutches (9.2%) were sired by three or more fathers, 17/22 (77.2%) were sired by two fathers, and only 3/22 (13.6%) clutches were sired by one father. Moreover, we reconstructed the paternal genotypes for 18 known mother-offspring clutches and found no evidence that females were favoring less related males or that less related males had higher fitness. However, males with greater heterozygosity sired more offspring. While the postcopulatory mechanisms underlying this pattern are not understood, female water dragons likely represent another example of reproduction through cryptic means (sperm selection/sperm competition) in a lizard, and through which they may ameliorate the effects of male-driven precopulatory sexual selection.

  8. The first iguanian lizard from the Mesozoic of Africa.

    Science.gov (United States)

    Apesteguía, Sebastián; Daza, Juan D; Simões, Tiago R; Rage, Jean Claude

    2016-09-01

    The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along with Gueragama sulamericana (Late Cretaceous of Brazil). The new fossil supports the previously hypothesized widespread geographical distribution of acrodontans in Gondwana during the Mesozoic. Additionally, it provides the first fossil evidence of uromastycines in the Cretaceous, and the ancestry of acrodontan iguanians in Africa.

  9. Remote sensing as a tool to analyse lizards behaviour

    Science.gov (United States)

    Dos Santos, Remi; Teodoro, Ana C.; Carretero, Miguel; Sillero, Neftalí

    2016-10-01

    Although the spatial context is expected to be a major influence in the interactions among organisms and their environment, it is commonly ignored in ecological studies. This study is part of an investigation on home ranges and their influence in the escape behaviour of Iberian lizards. Fieldwork was conducted inside a 400 m2 mesocosm, using three acclimatized adult male individuals. In order to perform analyses at this local scale, tools with high spatial accuracy are needed. A total of 3016 GPS points were recorded and processed into a Digital Elevation Model (DEM), with a pixel resolution of 2 cm. Then, 1156 aerial photos were taken and processed to create an orthophoto. A refuge map, containing possible locations for retreats was generated with supervised image classification algorithms, obtaining four classes (refuges, vegetation, bare soil and organic soil). Furthermore, 50 data-loggers were randomly placed, recording evenly through the area temperature and humidity every 15'. After a month of recording, all environmental variables were interpolated using Kriging. The study area presented an irregular elevation. The humidity varied according to the topography and the temperature presented a West-East pattern. Both variables are of paramount importance for lizard activity and performance. In a predation risk scenario, a lizard located in a temperature close to its thermal optimum will be able to escape more efficiently. Integration of such ecologically relevant elements in a spatial context exemplifies how remote sensing tools can contribute to improve inference in behavioural ecology.

  10. The first iguanian lizard from the Mesozoic of Africa

    Science.gov (United States)

    Apesteguía, Sebastián; Daza, Juan D.; Simões, Tiago R.; Rage, Jean Claude

    2016-09-01

    The fossil record shows that iguanian lizards were widely distributed during the Late Cretaceous. However, the biogeographic history and early evolution of one of its most diverse and peculiar clades (acrodontans) remain poorly known. Here, we present the first Mesozoic acrodontan from Africa, which also represents the oldest iguanian lizard from that continent. The new taxon comes from the Kem Kem Beds in Morocco (Cenomanian, Late Cretaceous) and is based on a partial lower jaw. The new taxon presents a number of features that are found only among acrodontan lizards and shares greatest similarities with uromastycines, specifically. In a combined evidence phylogenetic dataset comprehensive of all major acrodontan lineages using multiple tree inference methods (traditional and implied weighting maximum-parsimony, and Bayesian inference), we found support for the placement of the new species within uromastycines, along with Gueragama sulamericana (Late Cretaceous of Brazil). The new fossil supports the previously hypothesized widespread geographical distribution of acrodontans in Gondwana during the Mesozoic. Additionally, it provides the first fossil evidence of uromastycines in the Cretaceous, and the ancestry of acrodontan iguanians in Africa.

  11. Age-dependent social learning in a lizard.

    Science.gov (United States)

    Noble, Daniel W A; Byrne, Richard W; Whiting, Martin J

    2014-07-01

    Evidence of social learning, whereby the actions of an animal facilitate the acquisition of new information by another, is taxonomically biased towards mammals, especially primates, and birds. However, social learning need not be limited to group-living animals because species with less interaction can still benefit from learning about potential predators, food sources, rivals and mates. We trained male skinks (Eulamprus quoyii), a mostly solitary lizard from eastern Australia, in a two-step foraging task. Lizards belonging to 'young' and 'old' age classes were presented with a novel instrumental task (displacing a lid) and an association task (reward under blue lid). We did not find evidence for age-dependent learning of the instrumental task; however, young males in the presence of a demonstrator learnt the association task faster than young males without a demonstrator, whereas old males in both treatments had similar success rates. We present the first evidence of age-dependent social learning in a lizard and suggest that the use of social information for learning may be more widespread than previously believed.

  12. The usefulness of mesocosms for ecotoxicity testing with lacertid lizards

    Directory of Open Access Journals (Sweden)

    Maria José Amaral

    2012-12-01

    Full Text Available Mesocosms (i.e., outdoor, man-made representations of natural ecosystems have seldom been used to study the impact of contaminants on terrestrial ecosystems. However, mesocosms can be a useful tool to provide a link between field and laboratory studies. We exposed juvenile lacertid lizards for a period of over one year to pesticides (herbicides and insecticides in mesocosm enclosures with the intention of validating field observations obtained in a previous study that examined the effects of corn pesticides in Podarcis bocagei. Our treatments replicated field conditions and consisted of a control, an herbicides only treatment (alachlor, terbuthylazine, mesotrione and glyphosate and an herbicides and insecticide treatment (including chlorpyrifos. We used a multi-biomarker approach that examined parameters at an individual and sub-individual level, including growth, locomotor performance, standard metabolic rate, biomarkers of oxidative stress, esterases and liver histopathologies. Although mortality over the course of the exposures was high (over 60%, surviving individuals prospered relatively well in the mesocosms and displayed a broad range of natural behaviours. The low numbers of replicate animals compromised many of the statistical comparisons, but in general, surviving lizards exposed to pesticides in mesocosm enclosures for over one year, thrived, and displayed few effects of pesticide exposure. Despite the difficulties, this work acts as an important stepping-stone for future ecotoxicology studies using lizards.

  13. 75 FR 9377 - Endangered and Threatened Wildlife and Plants; Listing the Flat-Tailed Horned Lizard as Threatened

    Science.gov (United States)

    2010-03-02

    ... Flat- Tailed Horned Lizard as Threatened AGENCY: Fish and Wildlife Service, Interior. ACTION..., proposed rule to list the flat-tailed horned lizard (Phrynosoma mcallii) as threatened under the Endangered..., 1993 (58 FR 62624), to list the flat-tailed horned lizard as a threatened species, and reopens...

  14. Tests of the contribution of acclimation to geographic variation in water loss rates of the West Indian lizard Anolis cristatellus.

    Science.gov (United States)

    Gunderson, Alex R; Siegel, Jeremy; Leal, Manuel

    2011-10-01

    Phenotypic plasticity can contribute to the process of adaptive radiation by facilitating population persistence in novel environments. West Indian Anolis lizards provide a classic example of an adaptive radiation, in which divergence has occurred along two primary ecological axes: structural microhabitat and climate. Adaptive plasticity in limb morphology is hypothesized to have facilitated divergence along the structural niche axis in Anolis, but very little work has explored plasticity in physiological traits. Here, we experimentally ask whether Puerto Rican Anolis cristatellus from mesic and xeric habitats differ in desiccation rates, and whether these lizards exhibit an acclimation response to changes in relative humidity. We first present microclimatic data collected at lizard perch sites that demonstrate that abiotic conditions experienced by lizards differ between mesic and xeric habitat types. In Experiment 1, we measured desiccation rates of lizards from both habitats maintained under identical laboratory conditions. This experiment demonstrated that desiccation rates differ between populations; xeric lizards lose water more slowly than mesic lizards. In Experiment 2, lizards from each habitat were either maintained under the conditions of Experiment 1, or under extremely low relative humidity. Desiccation rates did not differ between lizards from the same habitat maintained under different treatments and xeric lizards maintained lower desiccation rates than mesic lizards within each treatment. Our results demonstrate that A. cristatellus does not exhibit an acclimation response to abrupt changes of hydric conditions, and suggest that tropical Anolis lizards might be unable to exhibit physiological plasticity in desiccation rates in response to varying climatic conditions.

  15. Sand engine quells the coast's hunger for sand

    NARCIS (Netherlands)

    Van Dijk, T.

    2012-01-01

    An artificial peninsula at Ter Heijde is designed to feed the coast with sediment. Scientists are investigating whether this kind of sand engine could be the Netherlands’ answer to rising sea levels.

  16. Sand engine quells the coast's hunger for sand

    NARCIS (Netherlands)

    Van Dijk, T.

    2012-01-01

    An artificial peninsula at Ter Heijde is designed to feed the coast with sediment. Scientists are investigating whether this kind of sand engine could be the Netherlands’ answer to rising sea levels.

  17. Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514

    CERN Document Server

    Catanese, M; Badran, H M; Biller, S D; Bond, I H; Boyle, P J; Bradbury, S M; Buckley, J H; Burdett, A M; Gordo, J B; Carter-Lewis, D A; Cawley, M F; Connaughton, V; Fegan, D J; Finley, J P; Gaidos, J A; Hall, T; Hillas, A M; Krennrich, F; Lamb, R C; Lessard, R W; Masterson, C; McEnery, J E; Mohanty, G B; Quinn, J; Rodgers, A J; Rose, H J; Samuelson, F W; Schubnell, M S; Sembroski, G H; Srinivasan, R; Weekes, T C; Wilson, C W; Zweerink, J A

    1997-01-01

    We present the discovery of >350 GeV gamma-ray emission from the BL Lacertae object 1ES 2344+514 with the Whipple Observatory 10m gamma-ray telescope. This is the third BL Lac object detected at gamma-ray energies above 300 Gev, the other two being Markarian 421 (Mrk 421) and Mrk501. These three active galactic nuclei are all X-ray selected and have the lowest known redshifts of any BL Lac objects currently identified. The evidence for emission derives primarily from an apparent flare on December 20, 1995 when a 6 sigma excess was detected with a flux approximately 63% of the very high energy gamma-ray emission from the Crab Nebula, the standard candle for TeV gamma-ray sources. Excluding the flare, observations between October 1995 and January 1996 yield a 4 sigma detection corresponding to 11% of the VHE Crab Nebula flux. Observations spanning September 1996 to January 1997 failed to yield a significant detection of a steady flux or any flaring. For this period, the 99.9% confidence level upper limit is <...

  18. An asteroseismic study of the beta Cephei star 12 Lacertae: multisite spectroscopic observations, mode identification and seismic modelling

    CERN Document Server

    Desmet, M; Thoul, A; Zima, W; De Cat, P; Handler, G; Ilyin, I; Kambe, E; Krzesínski, J; Lehmann, H; Masuda, S; Mathias, P; Mkrtichian, D E; Telting, J; Uytterhoeven, K; Yang, S L S; Aerts, C

    2009-01-01

    We present the results of a spectroscopic multisite campaign for the beta Cephei star 12 (DD) Lacertae. Our study is based on more than thousand high-resolution high S/N spectra gathered with 8 different telescopes in a time span of 11 months. In addition we make use of numerous archival spectroscopic measurements. We confirm 10 independent frequencies recently discovered from photometry, as well as harmonics and combination frequencies. In particular, the SPB-like g-mode with frequency 0.3428 1/d reported before is detected in our spectroscopy. We identify the four main modes as (l1,m1) = (1, 1), (l2,m2) = (0, 0), (l3,m3) = (1, 0) and (l4,m4) = (2, 1) for f1 = 5.178964 1/d, f2 = 5.334224 1/d, f3 = 5.066316 1/d and f4 = 5.490133 1/d, respectively. Our seismic modelling shows that f2 is likely the radial first overtone and that the core overshooting parameter alpha_ov is lower than 0.4 local pressure scale heights.

  19. Erratic Jet Wobbling in the BL Lacertae Object OJ287 Revealed by Sixteen Years of 7mm VLBA Observations

    CERN Document Server

    Agudo, Ivan; Jorstad, Svetlana G; Gomez, Jose L; Perucho, Manel; Piner, B Glenn; Rioja, Maria; Dodson, Richard

    2011-01-01

    We present the results from an ultra-high-resolution 7mm Very Long Baseline Array (VLBA) study of the relativistic jet in the BL Lacertae object OJ287 from 1995 to 2011 containing 136 total intensity images. Analysis of the image sequence reveals a sharp jet-position-angle swing by >100 deg. during [2004,2006], as viewed in the plane of the sky, that we interpret as the crossing of the jet from one side of the line of sight to the other during a softer and longer term swing of the inner jet. Modulating such long term swing, our images also show for the first time a prominent erratic wobbling behavior of the innermost ~0.4mas of the jet with fluctuations in position angle of up to ~40 deg. over time scales ~2yr. This is accompanied by highly superluminal motions along non-radial trajectories, which reflect the remarkable non-ballistic nature of the jet plasma on these scales. The erratic nature and short time scales of the observed behavior rules out scenarios such as binary black hole systems, accretion disk ...

  20. Structure and flux variability in the VLBI jet of BL Lacertae during the WEBT campaigns (1995--2004)

    CERN Document Server

    Bach, U; Raiteri, C M; Agudo, I; Aller, H D; Aller, M F; Denn, G; Gómez, J L; Jorstad, S; Marscher, A; Mutel, R L; Terasranta, H

    2006-01-01

    BL Lacertae has been the target of several observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration and is one of the best studied blazars at all accessible wavelengths. A recent analysis of the optical and radio variability indicates that part of the radio variability is correlated with the optical light curve. Here we present an analysis of a huge VLBI data set including 108 images at 15, 22, and 43 GHz obtained between 1995 and 2004. The aim of this study is to identify the different components contributing to the single-dish radio light curves. We obtain separate radio light curves for the VLBI core and jet and show that the radio spectral index of single-dish observations can be used to trace the core variability. Cross-correlation of the radio spectral index with the optical light curve indicates that the optical variations lead the radio by about 100 days at 15 GHz. By fitting the radio time lags vs. frequency, we find that the power law is steeper than expected for a freely expandi...

  1. The collective emission of electromagnetic waves from astrophysical jets - Luminosity gaps, BL Lacertae objects, and efficient energy transport

    Science.gov (United States)

    Baker, D. N.; Borovsky, Joseph E.; Benford, Gregory; Eilek, Jean A.

    1988-01-01

    A model of the inner portions of astrophysical jets is constructed in which a relativistic electron beam is injected from the central engine into the jet plasma. This beam drives electrostatic plasma wave turbulence, which leads to the collective emission of electromagnetic waves. The emitted waves are beamed in the direction of the jet axis, so that end-on viewing of the jet yields an extremely bright source (BL Lacertae object). The relativistic electron beam may also drive long-wavelength electromagnetic plasma instabilities (firehose and Kelvin-Helmholtz) that jumble the jet magnetic field lines. After a sufficient distance from the core source, these instabilities will cause the beamed emission to point in random directions and the jet emission can then be observed from any direction relative to the jet axis. This combination of effects may lead to the gap turn-on of astrophysical jets. The collective emission model leads to different estimates for energy transport and the interpretation of radio spectra than the conventional incoherent synchrotron theory.

  2. Spectroscopic characterization of a Nigerian standard sand: Igbokoda sand

    CSIR Research Space (South Africa)

    Ojuri, OO

    2017-01-01

    Full Text Available the Middle Ordovician St. Peter Sandstone near Ottawa, Illinois, had been picked by the American Society for Testing and Materials (ASTM) as the reference sand to employ in testing cement and strength of concrete [9]. To the best of our knowledge... and magnetic resonance spectroscopic techniques due to its importance in cement, geotechnical/geo-environmental research in Nigeria. This should halt importation of standard silica sand for mortar and concrete testing...

  3. Saltation of Non-Spherical Sand Particles

    Science.gov (United States)

    Wang, Zhengshi; Ren, Shan; Huang, Ning

    2014-01-01

    Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement. PMID:25170614

  4. Reclaimability of the spent sand mixture – sand with bentonite – sand with furfuryl resin

    Directory of Open Access Journals (Sweden)

    J. Dańko

    2011-04-01

    Full Text Available Introduction of new binding materials and new technologies of their hardening in casting moulds and cores production requires theapplication of reclamation methods adequate to their properties as well as special devices realizing tasks. The spent sands circulationsystem containing the same kind of moulding and core sands is optimal from the point of view of the expected reclamation results.However, in the face of a significant variability of applied technologies and related to them various reclamation methods, the need - of theobtained reclamation products assessment on the grounds of systematic criteria and uniform bases – arises, with a tendency of indicatingwhich criteria are the most important for the given sand system. The reclaimability results of the mixture of the spent moulding sand withGeko S bentonite and the spent core sand with the Kaltharz 404U resin hardened by acidic hardener 100 T3, are presented in the paper.Investigations were performed with regard to the estimation of an influence of core sands additions (10 –25% on the reclaimed materialquality. Dusts and clay content in the reclaim, its chemical reaction (pH and ignition loss were estimated. The verification of the reclaiminstrumental assessment was performed on the basis of the technological properties estimation of moulding sand with bentonite, where the reclaimed material was used as a matrix.

  5. 76 FR 19304 - Endangered and Threatened Wildlife and Plants; Endangered Status for Dunes Sagebrush Lizard

    Science.gov (United States)

    2011-04-07

    ... Fish and Wildlife Service 50 CFR Part 17 RIN 1018-AV97 Endangered and Threatened Wildlife and Plants; Endangered Status for Dunes Sagebrush Lizard AGENCY: Fish and Wildlife Service, Interior. ACTION: Proposed... rule to list the dunes sagebrush lizard (Sceloporus arenicolus) under the Endangered Species Act...

  6. Predicting micro thermal habitat of lizards in a dynamic thermal environment

    NARCIS (Netherlands)

    Fei, T.; Skidmore, A.K.; Venus, V.; Wang, T.; Toxopeus, A.G.; Bian, B.M.; Liu, Y.

    2012-01-01

    Understanding behavioural thermoregulation and its consequences is a central topic in ecology. In this study, a spatial explicit model was developed to simulate the movement and thermal habitat use of lizards in a controlled environment. The model incorporates a lizard's transient body temperatures

  7. A new scincid lizard of the genus Tribolonotus from Manus Island, New Guinea

    NARCIS (Netherlands)

    Cogger, H.G.

    1972-01-01

    INTRODUCTION The scincid lizards of the genus Tribolonotus are generally dull-coloured, armoured, thigmothermic, cryptozoic lizards with several unique features in their morphology and biology. These features include the possession of abdominal glands and volar pores, a vestigial left oviduct, the p

  8. Impact of the experimental removal of lizards on Lyme disease risk.

    Science.gov (United States)

    Swei, Andrea; Ostfeld, Richard S; Lane, Robert S; Briggs, Cheryl J

    2011-10-07

    The distribution of vector meals in the host community is an important element of understanding and predicting vector-borne disease risk. Lizards (such as the western fence lizard; Sceloporus occidentalis) play a unique role in Lyme disease ecology in the far-western United States. Lizards rather than mammals serve as the blood meal hosts for a large fraction of larval and nymphal western black-legged ticks (Ixodes pacificus--the vector for Lyme disease in that region) but are not competent reservoirs for the pathogen, Borrelia burgdorferi. Prior studies have suggested that the net effect of lizards is to reduce risk of human exposure to Lyme disease, a hypothesis that we tested experimentally. Following experimental removal of lizards, we documented incomplete host switching by larval ticks (5.19%) from lizards to other hosts. Larval tick burdens increased on woodrats, a competent reservoir, but not on deer mice, a less competent pathogen reservoir. However, most larvae failed to find an alternate host. This resulted in significantly lower densities of nymphal ticks the following year. Unexpectedly, the removal of reservoir-incompetent lizards did not cause an increase in nymphal tick infection prevalence. The net result of lizard removal was a decrease in the density of infected nymphal ticks, and therefore a decreased risk to humans of Lyme disease. Our results indicate that an incompetent reservoir for a pathogen may, in fact, increase disease risk through the maintenance of higher vector density and therefore, higher density of infected vectors.

  9. Statistical properties of spontaneous otoacoustic emissions in one bird and three lizard species

    NARCIS (Netherlands)

    vanDijk, P; Manley, GA; Gallo, L; Pavusa, A; Taschenberger, G

    1996-01-01

    Spontaneous otoacoustic emissions were recorded in the barn owl Tyto alba guttata (five ears), and in three lizard species (Callopistes maculatus, one ear; Varanus exanthematicus, seven ears; Gerrhonotus leiocephalus, one ear). The barn owl ears emitted one or two emission frequencies; the lizard

  10. A new scincid lizard of the genus Tribolonotus from Manus Island, New Guinea

    NARCIS (Netherlands)

    Cogger, H.G.

    1972-01-01

    INTRODUCTION The scincid lizards of the genus Tribolonotus are generally dull-coloured, armoured, thigmothermic, cryptozoic lizards with several unique features in their morphology and biology. These features include the possession of abdominal glands and volar pores, a vestigial left oviduct, the

  11. Statistical properties of spontaneous otoacoustic emissions in one bird and three lizard species

    NARCIS (Netherlands)

    vanDijk, P; Manley, GA; Gallo, L; Pavusa, A; Taschenberger, G

    1996-01-01

    Spontaneous otoacoustic emissions were recorded in the barn owl Tyto alba guttata (five ears), and in three lizard species (Callopistes maculatus, one ear; Varanus exanthematicus, seven ears; Gerrhonotus leiocephalus, one ear). The barn owl ears emitted one or two emission frequencies; the lizard ea

  12. Looking at a predator with the left or right eye: asymmetry of response in lizards.

    Science.gov (United States)

    Bonati, Beatrice; Csermely, Davide; Sovrano, Valeria Anna

    2013-01-01

    Studies carried out with the common wall lizard (Podarcis muralis) revealed preferential use of the left eye during responses to predatory threat in laboratory settings and in the wild. Here we tested lizards under monocular conditions of vision, using temporary eye-patching. Lizards were facing a (simulated) predatory threat laterally, from the side of the non-patched eye. Results showed that lizards with the left eye uncovered during predatory threat used the left eye to monitor the predator, whereas lizards with the right eye uncovered nonetheless tried to use the covered left eye. Moreover, lizards frequently tried to change the eye exposition, making a body C-bend behaviour. Right-eyed lizards showed more frequent and faster C-bending responses than left-eyed lizards, trying to monitor the predator with the left eye even though it was patched. Results fit with asymmetries in spontaneous eye use observed in laboratory conditions and in the wild in this species, confirming that structures located on the right side of the brain (mainly served by the left eye) predominantly attend to predatory threat.

  13. Geographic genetic differentiation of a malaria parasite, Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis.

    Science.gov (United States)

    Fricke, Jennifer M; Vardo-Zalik, Anne M; Schall, Jos J

    2010-04-01

    Gene flow, and resulting degree of genetic differentiation among populations, will shape geographic genetic patterns and possibly local adaptation of parasites and their hosts. Some studies of Plasmodium falciparum in humans show substantial differentiation of the parasite in locations separated by only a few kilometers, a paradoxical finding for a parasite in a large, mobile host. We examined genetic differentiation of the malaria parasite Plasmodium mexicanum, and its lizard host, Sceloporus occidentalis, at 8 sites in northern California, with the use of variable microsatellite markers for both species. These lizards are small and highly territorial, so we expected local genetic differentiation of both parasite and lizard. Populations of P. mexicanum were found to be differentiated by analysis of 5 markers (F(st) values >0.05-0.10) over distances as short as 230-400 m, and greatly differentiated (F(st) values >0.25) for sites separated by approximately 10 km. In contrast, the lizard host had no, or very low, levels of differentiation for 3 markers, even for sites >40 km distant. Thus, gene flow for the lizard was great, but despite the mobility of the vertebrate host, the parasite was locally genetically distinct. This discrepancy could result if infected lizards move little, but their noninfected relatives were more mobile. Previous studies on the virulence of P. mexicanum for fence lizards support this hypothesis. However, changing prevalence of the parasite, without changes in density of the lizard, could also result in this pattern.

  14. Management recommendations: Sand Lake Complex

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Sand Lake National Wildlife Refuge, by a land use specialist. Recommendations, time frame and...

  15. Change your diet or die: predator-induced shifts in insectivorous lizard feeding ecology.

    Science.gov (United States)

    Hawlena, Dror; Pérez-Mellado, Valentín

    2009-08-01

    Animal feeding ecology and diet are influenced by the fear of predation. While the mechanistic bases for such changes are well understood, technical difficulties often prevent testing how these mechanisms interact to affect a mesopredator's diet in natural environments. Here, we compared the insectivorous lizard Acanthodactylus beershebensis' feeding ecology and diet between high- and low-risk environments, using focal observations, intensive trapping effort and fecal pellet analysis. To create spatial variation in predation risk, we planted "artificial trees" in a scrubland habitat that lacks natural perches, allowing avian predators to hunt for lizards in patches that were previously unavailable to them. Lizards in elevated-risk environments became less mobile but did not change their microhabitat use or temporal activity. These lizards changed their diet, consuming smaller prey and less plant material. We suggest that diet shifts were mainly because lizards from risky environments consumed prey items that required shorter handling time.

  16. Effect of temperature on feeding period of larval blacklegged ticks (Acari: Ixodidae) on eastern fence lizards

    Science.gov (United States)

    Rulison, Eric L.; LeBrun, Roger A.; Ginsberg, Howard S.

    2014-01-01

    Ambient temperature can influence tick development time, and can potentially affect tick interactions with pathogens and with vertebrate hosts. We studied the effect of ambient temperature on duration of attachment of larval blacklegged ticks, Ixodes scapularis Say, to eastern fence lizards, Sceloporus undulatus (Bose & Daudin). Feeding periods of larvae that attached to lizards under preferred temperature conditions for the lizards (WARM treatment: temperatures averaged 36.6°C at the top of the cage and 25.8°C at the bottom, allowing behavioral thermoregulation) were shorter than for larvae on lizards held under cool conditions (COOL treatment temperatures averaged 28.4°C at top of cage and 24.9°C at the bottom). The lizards were infested with larvae four times at roughly monthly intervals. Larval numbers successfully engorging and dropping declined and feeding period was longer after the first infestation.

  17. Ecology and conservation of the endemic lizard Tropidurus hygomi in “restinga” habitats of the north coast of Bahia state, Brazil

    Directory of Open Access Journals (Sweden)

    Karina Vieira Martins

    2010-12-01

    Full Text Available “Restingas” are herbaceous/ shrubby coastal sand-dune habitats that cover great areas of Brazil, particularly along the Bahia state coast. The restingas are disturbed and are under strong pressure, mainly in northeastern Brazil. Fragmentation of the landscape and habitat loss within natural ecosystems are the factors which are mainly responsible for reduction of species diversity by extinction events. The goal of thepresent study was elucidate whether the conservation status of restinga habitats on the northern coast of Bahia state was interfering with microhabitat use by the endemic lizard Tropidurus hygomi. The results showed that the use of microhabitat resources by T. hygomi did not have any signifi cant differences in the four areas we chose for study. However, diverse factors of degradation were found to contribute indirectly to its habitat loss. The T. hygomi lizard is a generalist in its use of restinga microhabitats, and probably due the endemic condition, its conservation status is linked directly to conservation of the restinga habitats on the northern coast of Bahia state.

  18. Perch-height specific predation on tropical lizard clay models: implications for habitat selection in mainland neotropical lizards

    Directory of Open Access Journals (Sweden)

    John E Steffen

    2009-09-01

    Full Text Available Predation has been hypothesized to be a strong selective force structuring communities of tropical lizards. Comparisons of perch height and size-based predation frequencies can provide a unique window into understanding how predation might shape habitat selection and morphological patterns in lizards, especially anoles. Here i use plasticine clay models, placed on the trunks of trees and suspended in the canopy to show that predation frequency on clay models differs primarily according to habitat (canopy vs. trunk-ground, but not according to size. These data are discussed in light of observed lizard abundances in the lowland forests of Costa Rica, and are presented as partial explanation for why fewer lizards are found in tree canopies, and more lizards are found on ground-trunk habitats. Rev. Biol. Trop. 57 (3: 859-864. Epub 2009 September 30.Existe la hipótesis de que la depredación es una fuerte fuerza selectiva que estructura las comunidades de lagartijas tropicales. Las comparaciones de las frecuencias de altura de la percha y de depredación con base en el tamaño pueden proveer una ventana única en el entendimiento de cómo la depredación podría moldear la selección del hábitat y los patrones morfológicos en las lagartijas, especialmente anoles. En este estudio uso modelos de plasticina, ubicados en troncos de árboles y suspendidos en el dosel para mostrar que la frecuencia de depredación en los modelos de plasticina difiere primariamente según el hábitat (dosel vs. tronco-suelo pero no según el tamaño. Estos datos se discuten a la luz de las abundancias de lagartijas observadas en los bosques de bajura de Costa Rica, y se presentan como una explicación parcial a porqué menos lagartijas se encuentran en los doseles, y más lagartijas se encuentran en los hábitats suelo-tronco.

  19. The lizard celestial compass detects linearly polarized light in the blue.

    Science.gov (United States)

    Beltrami, Giulia; Parretta, Antonio; Petrucci, Ferruccio; Buttini, Paola; Bertolucci, Cristiano; Foà, Augusto

    2012-09-15

    The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.

  20. Microhabitat occupation and functional morphology of four species of sympatric agamid lizards in the Kyzylkum Desert, central Uzbekistán

    Directory of Open Access Journals (Sweden)

    Clemann, N.

    2008-12-01

    Full Text Available We examined microhabitat occupation and functional morphology of four sympatric agamid lizards (Phrynocephalus helioscopus helioscopus, P. interscapularis, P. mystaceus galli and Trapelus sanguinolentus at three sites in the arid zone of central Uzbekistan. At two sites located in sand dunes, substrate attributes played a key role in habitat selection by three syntopic species. At a third flat, stony site, P. helioscopus selected habitat non–randomly, tending to occur close to sparse, low vegetation. Syntopic taxa were separated in morphospace, and there was a trend for taxa with proportionally longer limbs to have faster field escape speeds. Field escape distances and predator avoidance tactics differed between species, with two main escape strategies (crypsis or sand–diving following an escape sprint. We caution that broad–scale threatening processes such as over–grazing and salinity may be having a detrimental effect on microhabitat features important to terrestrial reptiles in Uzbekistan.

  1. Potential distribution of the endangered endemic lizard Liolaemus lutzae Mertens, 1938 (Liolaemidae: are there other suitable areas for a geographically restricted species?

    Directory of Open Access Journals (Sweden)

    GR. Winck

    Full Text Available In this study we attempted to access further information on the geographical distribution of the endangered lizard Liolaemus lutzae, estimating its potential distribution through the maximum entropy algorithm. For this purpose, we related its points of occurrence with matrices of environmental variables. After examining the correlation between environmental matrices, we selected 10 for model construction. The main variables influencing the current geographic distribution of L. lutzae were the diurnal temperature range and altitude. The species endemism seemed to be a consequence of a reduction of the original distribution area. Alternatively, the resulting model may reflect the geographic distribution of an ancestral lineage, since the model selected areas of occurrence of the two other species of Liolaemus from Brazil (L. arambarensis and L. occipitalis, all living in sand dune habitats and having psamophilic habits. Due to the high loss rate of habitat occupied by the species, the conservation and recovery of the remaining areas affected by human actions is essential.

  2. Thermal dependence of sprint performance in the lizard Psammodromus algirus along a 2200-meter elevational gradient: Cold-habitat lizards do not perform better at low temperatures.

    Science.gov (United States)

    Zamora-Camacho, Francisco Javier; Rubiño-Hispán, María Virtudes; Reguera, Senda; Moreno-Rueda, Gregorio

    2015-08-01

    Sprint speed has a capital relevance in most animals' fitness, mainly for fleeing from predators. Sprint performance is maximal within a certain range of body temperatures in ectotherms, whose thermal upkeep relies on exogenous thermal sources. Ectotherms can respond to diverse thermal environments either by shifting their thermal preferences or maintaining them through different adaptive mechanisms. Here, we tested whether maximum sprint speed of a lizard that shows conservative thermal ecology along a 2200-meter elevational gradient differs with body temperature in lizards from different elevations. Lizards ran faster at optimum than at suboptimum body temperature. Notably, high-elevation lizards were not faster than mid- and low-elevation lizards at suboptimum body temperature, despite their low-quality thermal environment. This result suggests that both preferred body temperature and thermal dependence of speed performance are co-adapted along the elevational gradient. High-elevation lizards display a number of thermoregulatory strategies that allow them to achieve high optimum body temperatures in a low thermal-quality habitat and thus maximize speed performance. As for reproductive condition, we did not find any effect of it on sprint speed, or any significant interaction with elevation or body temperature. However, strikingly, gravid females were significantly slower than males and non-gravid females at suboptimum temperature, but performed similarly well at optimal temperature.

  3. [Home range of Aspidoscelis cozumela (Squamata: Teiidae): a parthenogenetic lizard microendemic to Cozumel Island, México].

    Science.gov (United States)

    Hernández-Gallegos, Oswaldo; López-Moreno, Ana Esthela; Méndez-Sánchez, José Fernando; Rheubert, Justin Lloyd; Méndez-de la Cruz, Fausto Roberto

    2015-09-01

    Home range is defined as the area within which an individual moves to acquire resources necessary to increase their fitness and may vary inter and intra-specifically with biotic and abiotic factors. This study details the home range of the parthenogenic lizard, Aspidoscelis cozumela, an active forager microendemic to Cozumel Island, México, with high preference for open sand beaches. The home range of A. cozumela was compared with other species of Aspidoscelis (gonochoric and parthenogenetic) and other lizards that occupy coastal habitats. Furthermore, the biotic and abiotic factors that may influence home range were analyzed. This study was conducted in the beach located on the East side of the island (area of 4,000 M2) that is composed primarily of halophyte vegetation with high levels of sunlight. From 1999 to 2001, nine samples were taken which included the dry, rainy, "nortes", and breeding seasons. During each sampling, capture-mark-recapture techniques were conducted and the date, time of day, and snout-vent length (SVL) were recorded to the nearest millimeter. Individuals were located in the study area using a bi-coordinate reference using 10 x 10 m subdivisions of the habitat. Home range and home range overlap were calculated using the convex polygon method in McPaal and home range/SVL correlation was tested using Pearson's correlation. To calculate females home range, three or more recaptures were considered. A total of 20 home ranges that averaged 45.1 ± 14.0 m2 were obtained and no correlation between SVL and home range size was detected (p = 0.9229, n = 20). However, removing individuals with outlier home ranges (females with home ranges > 100 m2, n = 2) resulted in a positive correlation with SVL (r = 0.61, p = 0.0072, n = 18). A 22.9 ± 5.7% overlap in home range was also detected. The small home range of A. cozumela represents the smallest home range within the Aspidoscelis genus recorded to date (including both parthenogenetic and gonochoric

  4. Body Size and Reproductive Tactics in Varanid lizards

    Institute of Scientific and Technical Information of China (English)

    Yu DU; Longhui LIN; Yuntao YAO; Chixian LIN; Xiang JI

    2014-01-01

    Body size and female reproduction in the water monitor lizard(Varanus salvator) were studied. Forty-two adult females larger than 500 mm SVL and 32 adult males larger than 400 mm SVL were donated by local people in Ledong, Hainan under permit to our laboratory in Hainan in 2013 and 2014. The largest male and female measured 745 and 755 mm SVL, respectively. The mean SVL was greater in adult females than in adult males. Males had larger heads (head width) than females of the same SVL. The smallest reproductive female in our sample was 565 mm SVL. Females produced a single clutch of 17.1 (10−23) pliable-shelled eggs per breeding season stretching from mid-June and mid-September. Clutch size and clutch mass were all positively related to female SVL. However, there was no signiifcant linear relationship between egg mass and female SVL. Larger females generally produced more eggs, and thus heavier clutches than did smaller ones. There was no signiifcant linear relationship between relative clutch mass and female SVL. Phylogenetic generalized least squares (PGLS) analysis, accounting for phylogenetic relationships, showed that clutch size was positively correlated with mean maternal SVL in varanid lizards. PGLS analysis showed that phylogenetic relationships did not affect clutch (or/and egg) mass and the SVL although there were significant linear relationship between clutch (or/and egg) mass and mean maternal SVL. Therefore, we could draw some general conclusions about the body size and reproductive tactics in varanid lizards that larger females generally produced more eggs, larger eggs and thus heavier clutches than did smaller ones.

  5. Sexual dimorphism in digit length ratios in two lizard species.

    Science.gov (United States)

    Rubolini, Diego; Pupin, Fabio; Sacchi, Roberto; Gentilli, Augusto; Zuffi, Marco A L; Galeotti, Paolo; Saino, Nicola

    2006-05-01

    Sexual dimorphism in digit length ratios has been reported for humans, a few other mammals, and two bird species. This dimorphism is thought to arise via an interaction between the prenatal exposure of the embryo to sex hormones and the Hox genes, which are highly conserved among vertebrates and control the development of both the appendices, including fingers and toes, and the urogenital system. In this study, we report on sexual dimorphism in 2D:3D, 2D:4D, and 3D:4D contralateral ratios of the forelimbs in two species of oviparous lizards, the common wall lizard (Podarcis muralis) and the tree skink (Mabuya planifrons), as measured on museum specimens. We found that male P. muralis had a larger 2D:4D ratio on both sides and larger 2D:3D ratio on the left side than females, whereas in M. planifrons, males had lower 2D:3D ratios than females on the left side. The two species show opposite patterns of sexual dimorphism in body size, males being larger than females in P. muralis, and the reverse in M. planifrons, suggesting that interspecific variation of sex differences in digit ratios could be associated with sex-specific growth trajectories. There was a limited evidence for directional asymmetry in digit ratios. Therefore, our findings provide the first evidence that digit ratios are sexually dimorphic in any reptile species and are consistent with the idea that the genetic link between limb development and the urogenital system had been established with the evolution of the earliest terrestrial tetrapods. Importantly, many lizard species with genetic sex determination, including the ones we studied, are oviparous and may represent valuable animal models for experimental tests of the association between prenatal exposure to androgens or estrogens and digit ratios.

  6. Chasing the Patagonian sun: comparative thermal biology of Liolaemus lizards.

    Science.gov (United States)

    Azócar, Débora Lina Moreno; Vanhooydonck, Bieke; Bonino, Marcelo F; Perotti, M Gabriela; Abdala, Cristian S; Schulte, James A; Cruz, Félix B

    2013-04-01

    The importance of the thermal environment for ectotherms and its relationship with thermal physiology and ecology is widely recognized. Several models have been proposed to explain the evolution of the thermal biology of ectotherms, but experimental studies have provided mixed support. Lizards from the Liolaemus goetschi group can be found along a wide latitudinal range across Argentina. The group is monophyletic and widely distributed, and therefore provides excellent opportunities to study the evolution of thermal biology. We studied thermal variables of 13 species of the L. goetschi group, in order to answer three questions. First, are aspects of the thermal biology of the L. goetschi group modelled by the environment or are they evolutionarily conservative? Second, have thermal characteristics of these animals co-evolved? And third, how do the patterns of co-evolution observed within the L. goetschi group compare to those in a taxonomically wider selection of species of Liolaemus? We collected data on 13 focal species and used species information of Liolaemus lizards available in the literature and additional data obtained by the authors. We tackled these questions using both conventional and phylogenetically based analyses. Our results show that lizards from the L. goetschi group and the genus Liolaemus in general vary in critical thermal minimum in relation to mean air temperature, and particularly the L. goetschi group shows that air temperature is associated with critical thermal range, as well as with body temperature. Although the effect of phylogeny cannot be ignored, our results indicate that these thermal biology aspects are modelled by cold environments of Patagonia, while other aspects (preferred body temperature and critical thermal maximum) are more conservative. We found evidence of co-evolutionary patterns between critical thermal minimum and preferred body temperature at both phylogenetic scales (the L. goetschi group and the extended sample of

  7. Telling tails: selective pressures acting on investment in lizard tails.

    Science.gov (United States)

    Fleming, Patricia A; Valentine, Leonie E; Bateman, Philip W

    2013-01-01

    Caudal autotomy is a common defense mechanism in lizards, where the animal may lose part or all of its tail to escape entrapment. Lizards show an immense variety in the degree of investment in a tail (i.e., length) across species, with tails of some species up to three or four times body length (snout-vent length [SVL]). Additionally, body size and form also vary dramatically, including variation in leg development and robustness and length of the body and tail. Autotomy is therefore likely to have fundamentally different effects on the overall body form and function in different species, which may be reflected directly in the incidence of lost/regenerating tails within populations or, over a longer period, in terms of relative tail length for different species. We recorded data (literature, museum specimens, field data) for relative tail length (n=350 species) and the incidence of lost/regenerating tails (n=246 species). We compared these (taking phylogeny into account) with intrinsic factors that have been proposed to influence selective pressures acting on caudal autotomy, including body form (robustness, body length, leg development, and tail specialization) and ecology (foraging behavior, physical and temporal niches), in an attempt to identify patterns that might reflect adaptive responses to these different factors. More gracile species have relatively longer tails (all 350 spp., P lizards (all 246 spp., P < 0.01; Scindidae, P < 0.05), larger skinks (P < 0.05), climbing geckos (P < 0.05), or active-foraging iguanids (P < 0.05). The selective advantage of investing in a relatively longer tail may be due to locomotor mechanics, although the patterns observed are also largely consistent with predictions based on predation pressure.

  8. Sexual differences in behavioral thermoregulation of the lizard Scelarcis perspicillata.

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-10-01

    Temperature determines all aspects of the biology of ectotherms. Although sexual differences in thermal ecology are not the rule in lizards, some species exhibit such differences. We studied the effect of sex and reproductive condition on the thermoregulation of an introduced population of Scelarcis perspicillata during the summer in Menorca (Balearic Islands, Spain). These lizards live in the wall surfaces of a limestone quarry, where the sun is scarce because of the narrowness of the quarry walls. The population is sexually dimorphic, with larger males than females. We measured body temperature (Tb) of adult males and females in the field, and air (Ta) and substrate temperature (Ts) at the capture sites, and recorded exposure to sunlight, height of the perch, and type of substrate. We also recorded operative temperatures (Te) as a null hypothesis of thermoregulation. Finally, we studied the thermal preferences of adult males and females in a laboratory thermal gradient. Thermal preferences were similar for pregnant and non-pregnant females, and sex did not affect the thermal preferences of lizards, even after controlling for the effect of body size. However, in the field, females achieved higher Tb than males, and occupied microhabitats with higher Ta and Ts and lower perch heights than males. Furthermore, females selected perches in full sun at a higher frequency than males. As a consequence, females achieved a higher accuracy and effectiveness of thermoregulation (0.89) than males (0.84). Thus, all else being equal, females would achieve a higher performance than males. The observed results are attributable to sexual differences in behaviour, probably in relation with the reproductive season. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Effects of Cadmium on the Glial Architecture in Lizard Brain

    Science.gov (United States)

    Favorito, Rossana; Monaco, Antonio; Grimaldi, Maria C.; Ferrandino, Ida

    2017-01-01

    The glial cells are positioned to be the first cells of the brain parenchyma to face molecules crossing the blood-brain barrier with a relevant neuroprotective role from cytotoxic action of heavy metals on the nervous system. Cadmium is a highly toxic metal and its levels in the environment are increasing due to industrial activities. This element can pass the blood-brain barrier and have neurotoxic activity. For this reason we have studied the effects of cadmium on the glial architecture in the lizard Podarcis siculus, a significant bioindicator of chemical exposure due to its persistence in a variety of habitats. The study was performed on two groups of lizards. The first group of P. siculus was exposed to an acute treatment by a single i.p. injection (2 mg/kg-BW) of CdCl2 and sacrificed after 2, 7 and 16 days. The second one was used as control. The histology of the brain was studied by Hematoxylin/Eosin and Cresyl/Violet stains while the glial structures were analyzed by immunodetection of the glial fibrillary acidic protein (GFAP), the most widely accepted marker for astroglial cells. Evident morphological alterations of the brain were observed at 7 and 16 days from the injection, when we revealed also a decrease of the GFAP-immunopositive structures in particular in the rhombencephalic ventricle, telencephalon and optic tectum. These results show that in the lizards an acute exposure to cadmium provokes morphological cellular alterations in the brain but also a decrement of the expression of GFAP marker with possible consequent damage of glial cells functions.

  10. Thermoregulatory consequences of salt loading in the lizard Pogona vitticeps.

    Science.gov (United States)

    Scarpellini, Carolina da Silveira; Bícego, Kênia C; Tattersall, Glenn J

    2015-04-15

    Previous research has demonstrated that dehydration increases the threshold temperature for panting and decreases the thermal preference of lizards. Conversely, it is unknown whether thermoregulatory responses such as shuttling and gaping are similarly influenced. Shuttling, as an active behavioural response, is considered one of the most effective thermoregulatory behaviours, whereas gaping has been proposed to be involved in preventing brain over-heating in lizards. In this study we examined the effect of salt loading, a proxy for increased plasma osmolality, on shuttling and gaping in Pogona vitticeps. Then, we determined the upper and lower escape ambient temperatures (UETa and LETa), the percentage of time spent gaping, the metabolic rate (V̇O2 ), the evaporative water loss (EWL) during gaping and non-gaping intervals and the evaporative effectiveness (EWL/V̇O2 ) of gaping. All experiments were performed under isotonic (154 mmol l(-1)) and hypertonic saline injections (625, 1250 or 2500 mmol l(-1)). Only the highest concentration of hypertonic saline altered the UETa and LETa, but this effect appeared to be the result of diminishing the animal's propensity to move, instead of any direct reduction in thermoregulatory set-points. Nevertheless, the percentage of time spent gaping was proportionally reduced according to the saline concentration; V̇O2 was also decreased after salt loading. Thermographic images revealed lower head than body surface temperatures during gaping; however this difference was inhibited after salt loading. Our data suggest that EWL/V̇O2 is raised during gaping, possibly contributing to an increase in heat transfer away from the lizard, and playing a role in head or brain cooling. © 2015. Published by The Company of Biologists Ltd.

  11. Disturbance of the inclined inserting-type sand fence to wind-sand flow fields and its sand control characteristics

    Science.gov (United States)

    Cheng, Jian-jun; Lei, Jia-qiang; Li, Sheng-yu; Wang, Hai-feng

    2016-06-01

    The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind-sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

  12. Multicolor Optical Monitoring of the BL Lacertae Object S5 0716+714 during the 2012 Outburst

    Science.gov (United States)

    Hong, Shanwei; Xiong, Dingrong; Bai, Jinming

    2017-08-01

    We monitored the BL Lacertae object S5 0716+714 in the optical bands during 2012 January and February with long time spans on intraday timescales (>5 hr) and high time resolutions. During this monitoring period, the object shows violent flaring activity in both short and intraday timescales. The object has a high duty cycle. The light curves detected as intraday variability show variability of various shapes. The variability amplitude is from 12.81% to 33.22%, and the average value is 19.92% ± 5.87%. The overall magnitude variabilities are \\bigtriangleup B=1\\buildrel{{m}}\\over{.} 24, \\bigtriangleup V=1\\buildrel{{m}}\\over{.} 42, \\bigtriangleup R=1\\buildrel{{m}}\\over{.} 3, and \\bigtriangleup I=1\\buildrel{{m}}\\over{.} 23. During the observations, the average change rate is =0.035+/- 0.009 Mag/h during the ascent and =0.035+/- 0.014 Mag/h during the descent. However, different cases are found on certain nights. There are good interband correlations but no significant time lags for intraday and short timescales. The results of the autocorrelation function show that the variability timescales range from 0.054 to 0.134 day. Most nights show a bluer-when-brighter (BWB) chromatic trend, a weak redder-when-brighter (RWB) trend is found, and a few nights show no correlation between magnitude and color index. The BWB trend appears in short timescales. During the flare, the spectral index exhibits a clockwise loop for internights. A shock-in-jet model and the shock wave propagating along a helical path are likely to explain the variability and color index variability.

  13. ERRATIC JET WOBBLING IN THE BL LACERTAE OBJECT OJ287 REVEALED BY SIXTEEN YEARS OF 7 mm VLBA OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Agudo, Ivan; Gomez, Jose L. [Instituto de Astrofisica de Andalucia, CSIC, Apartado 3004, 18080 Granada (Spain); Marscher, Alan P.; Jorstad, Svetlana G. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Perucho, Manel [Departament d' Astronomia i Astrofisica, Universitat de Valencia, Dr. Moliner 50, E-46100 Burjassot, Valencia (Spain); Piner, B. Glenn [Department of Physics and Astronomy, Whittier College, 13406 East Philadelphia Street, Whittier, CA 90608 (United States); Rioja, Maria [Observatorio Astronomico Nacional, Apdo. 112, E-28803 Alcala de Henares, Madrid (Spain); Dodson, Richard, E-mail: iagudo@iaa.es [ICRAR/University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

    2012-03-01

    We present the results from an ultra-high-resolution 7 mm Very Long Baseline Array study of the relativistic jet in the BL Lacertae object OJ287 from 1995 to 2011 containing 136 total intensity images. Analysis of the image sequence reveals a sharp jet-position-angle swing by >100 Degree-Sign during [2004,2006], as viewed in the plane of the sky, which we interpret as the crossing of the jet from one side of the line of sight to the other during a softer- and longer-term swing of the inner jet. Modulating such long-term swing, our images also show for the first time a prominent erratic wobbling behavior of the innermost {approx}0.4 mas of the jet with fluctuations in position angle of up to {approx}40 Degree-Sign over timescales {approx}2 yr. This is accompanied by highly superluminal motions along non-radial trajectories, which reflect the remarkable non-ballistic nature of the jet plasma on these scales. The erratic nature and short timescales of the observed behavior rule out scenarios such as binary black hole systems, accretion disk precession, and interaction with the ambient medium as possible origins of the phenomenon on the scales probed by our observations, although such processes may cause longer-term modulation of the jet direction. We propose that variable asymmetric injection of the jet flow, perhaps related to turbulence in the accretion disk, coupled with hydrodynamic instabilities leads to the non-ballistic dynamics that causes the observed non-periodic changes in the direction of the inner jet.

  14. Optimal array of sand fences.

    Science.gov (United States)

    Lima, Izael A; Araújo, Ascânio D; Parteli, Eric J R; Andrade, José S; Herrmann, Hans J

    2017-03-24

    Sand fences are widely applied to prevent soil erosion by wind in areas affected by desertification. Sand fences also provide a way to reduce the emission rate of dust particles, which is triggered mainly by the impacts of wind-blown sand grains onto the soil and affects the Earth's climate. Many different types of fence have been designed and their effects on the sediment transport dynamics studied since many years. However, the search for the optimal array of fences has remained largely an empirical task. In order to achieve maximal soil protection using the minimal amount of fence material, a quantitative understanding of the flow profile over the relief encompassing the area to be protected including all employed fences is required. Here we use Computational Fluid Dynamics to calculate the average turbulent airflow through an array of fences as a function of the porosity, spacing and height of the fences. Specifically, we investigate the factors controlling the fraction of soil area over which the basal average wind shear velocity drops below the threshold for sand transport when the fences are applied. We introduce a cost function, given by the amount of material necessary to construct the fences. We find that, for typical sand-moving wind velocities, the optimal fence height (which minimizes this cost function) is around 50 cm, while using fences of height around 1.25 m leads to maximal cost.

  15. Modelling asymmetry in the peripheral auditory system of the lizard

    DEFF Research Database (Denmark)

    Zhang, Lei; Hallam, John; Christensen-Dalsgaard, Jakob

    2008-01-01

    The ears of lizards are highly directional. The directionality is generated by strong acoustical coupling of the eardrums. A simple lumped-parameter model of the ear followed by binaural comparisons has been shown to perform successful phonotaxis in robot implementations. However, such a model...... will produce localization erros in the form of  response bias if the ears are asymmetrical. We have evaluated how large errors are generated by asymmetry using simulations of the ear model in Mathematica 5.2. The study shows that the effect of asymmetry is minimal around the most directional frequency...

  16. Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. I. Imaging BL Lacertae at 21 microarcsecond resolution

    CERN Document Server

    Gómez, José L; Bruni, Gabriele; Kovalev, Yuri Y; Marscher, Alan P; Jorstad, Svetlana G; Mizuno, Yosuke; Bach, Uwe; Sokolovsky, Kirill V; Anderson, James M; Galindo, Pablo; Kardashev, Nikolay S; Lisakov, Mikhail M

    2016-01-01

    We present the first polarimetric space VLBI imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be within 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9 Earth's diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 $\\mu$as, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 $\\mu$as from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 $\\mu$as and 250 $\\mu$as from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analy...

  17. The relative influence of road characteristics and habitat on adjacent lizard populations in arid shrublands

    Science.gov (United States)

    Hubbard, Kaylan A.; Chalfoun, Anna D.; Gerow, Kenneth G.

    2016-01-01

    As road networks continue to expand globally, indirect impacts to adjacent wildlife populations remain largely unknown. Simultaneously, reptile populations are declining worldwide and anthropogenic habitat loss and fragmentation are frequently cited causes. We evaluated the relative influence of three different road characteristics (surface treatment, width, and traffic volume) and habitat features on adjacent populations of Northern Sagebrush Lizards (Sceloporus graciosus graciosus), Plateau Fence Lizards (S. tristichus), and Greater Short-Horned Lizards (Phrynosoma hernandesi) in mixed arid shrubland habitats in southwest Wyoming. Neither odds of lizard presence nor relative abundance was significantly related to any of the assessed road characteristics, although there was a trend for higher Sceloporus spp. abundance adjacent to paved roads. Sceloporus spp. relative abundance did not vary systematically with distance to the nearest road. Rather, both Sceloporus spp. and Greater Short-Horned Lizards were associated strongly with particular habitat characteristics adjacent to roads. Sceloporus spp. presence and relative abundance increased with rock cover, relative abundance was associated positively with shrub cover, and presence was associated negatively with grass cover. Greater Short-Horned Lizard presence increased with bare ground and decreased marginally with shrub cover. Our results suggest that habitat attributes are stronger correlates of lizard presence and relative abundance than individual characteristics of adjacent roads, at least in our system. Therefore, an effective conservation approach for these species may be to consider the landscape through which new roads and their associated development would occur, and the impact that placement could have on fragment size and key habitat elements.

  18. Regulation of skeletal muscle metabolism in the lizard Dipsosaurus dorsalis by fructose-2,6-bisphosphate.

    Science.gov (United States)

    Scholnick, D A; Gleeson, T T

    1996-11-01

    Changes in liver and skeletal muscle fructose-2,6-bisphosphate (Fru-2,6-P2) concentrations were compared during fasting, exercise, and recovery in the lizard Dipsosaurus dorsalis and in outbred mice (Mus musculus). We present the first correlative evidence that suggests that a decrease in the content of Fru-2,6-P2 may mediate elevated gluconeogenesis in lizard skeletal muscle. Contents of Fru-2,6-P2 in lizard gastrocnemius and red and white iliofibularis (IF) were significantly lower (as much as 55% in white IF) during recovery from exhaustive exercise than at rest. Recovery from exhaustive exercise had no significant effect on Fru-2,6-P2 concentrations in any mouse muscle examined. Fasting significantly depressed lizard and mouse liver Fru-2,6-P2 contents and decreased lizard red IF by over 84% from the fed condition. Lizard red and white muscle fiber bundles incubated in 20 mM lactate had significantly lower Fru-2,6-P2 (94 and 61% depression, respectively) than those incubated in 8.5 mM glucose. These results are consistent with the hypothesis that Fru-2,6-P2 acts as a signal for controlling gluconeogenesis in lizard skeletal muscle.

  19. Diagnostic sensitivity of ultrasound, radiography and computed tomography for gender determination in four species of lizards.

    Science.gov (United States)

    Di Ianni, Francesco; Volta, Antonella; Pelizzone, Igor; Manfredi, Sabrina; Gnudi, Giacomo; Parmigiani, Enrico

    2015-01-01

    Gender determination is frequently requested by reptile breeders, especially for species with poor or absent sexual dimorphism. The aims of the current study were to describe techniques and diagnostic sensitivities of ultrasound, radiography, and computed tomography for gender determination (identification of hemipenes) in four species of lizards. Nineteen lizards of known sex, belonging to four different species (Pogona vitticeps, Uromastyx aegyptia, Tiliqua scincoides, Gerrhosaurus major) were prospectively enrolled. With informed owner consent, ultrasound, noncontrast CT, contrast radiography, and contrast CT (with contrast medium administered into the cloaca) were performed in conscious animals. Imaging studies were reviewed by three different operators, each unaware of the gender of the animals and of the results of the other techniques. The lizard was classified as a male when hemipenes were identified. Nineteen lizards were included in the study, 10 females and nine males. The hemipenes were seen on ultrasound in only two male lizards, and appeared as oval hypoechoic structures. Radiographically, hemipenes filled with contrast medium appeared as spindle-shaped opacities. Noncontrast CT identified hemipenes in only two lizards, and these appeared as spindle-shaped kinked structures with hyperattenuating content consistent with smegma. Hemipenes were correctly identified in all nine males using contrast CT (accuracy of 100%). Accuracy of contrast radiography was excellent (94.7%). Accuracy of ultrasound and of noncontrast CT was poor (64.3% and 63.1%, respectively). Findings from the current study supported the use of contrast CT or contrast radiography for gender determination in lizards.

  20. One solution for two challenges: the lizard Microlophus atacamensis avoids overheating by foraging in intertidal shores.

    Science.gov (United States)

    Sepúlveda, Maritza; Sabat, Pablo; Porter, Warren P; Fariña, José Miguel

    2014-01-01

    In lizards, one of the most important behavioral mechanisms to cope with spatial and temporal variations in thermal resources observed is activity time. The longer a lizard can maintain activity, the more time it has to forage and reach larger adult body size. We studied the behavioral adjustments to different climatic regimens on daily and seasonal scales in three natural populations of the lizard Microlophus atacamensis along a latitudinal temperature and rainfall gradient. We also used Niche Mapper to determinate the amount of thermally suitable time for activity for this species. Abundance and daily activity patterns varied greatly over the year for the three populations. In summer and spring, the daily activity times were greater, and were reduced in fall and winter seasons. In summer, when stressful heat loads should prohibit activity over a midday gap, lizards did not show bimodal patterns of activity. Instead, they move to the cooler intertidal habitat. Abundance and thermal quality in the southernmost coolest site was lower, and the potential annual activity time decreases with latitude. Contrary to expectations, lizards from this locality showed the largest body sizes possibly due to diet and/or time to sexual maturation. Our results indicate that the intertidal habitat is a key factor that influences daily and seasonal activity of M. atacamensis lizards. While this habitat is not climatically optimal for lizards, it allows them to behaviorally extend their activity window and gain access to food in the intertidal areas.

  1. Thyroid disruption in the lizard Podarcis bocagei exposed to a mixture of herbicides: a field study.

    Science.gov (United States)

    Bicho, Rita C; Amaral, Maria José; Faustino, Augusto M R; Power, Deborah M; Rêma, Alexandra; Carretero, Miguel A; Soares, Amadeu M V M; Mann, Reinier M

    2013-01-01

    Pesticide exposure has been related with thyroid disrupting effects in different vertebrate species. However, very little is known about the effects of these compounds in reptiles. In the Mediterranean area, lacertid lizards are the most abundant vertebrate group in agroecosystems, and have been identified as potential model species for reptile ecotoxicology. The aim of this study was to understand if the herbicides applied in corn fields have thyroid disruptive effects in the lizard Podarcis bocagei. Adult male lizards were captured in north-western Portugal in corn fields treated with herbicides (exposed sites), and in organic agricultural fields (reference sites). Thyroid and male gonad morphology and functionality, and testosterone levels were investigated through histological, immunohistochemical and biochemical techniques. Lizards from exposed locations displayed thyroid follicular lumens with more reabsorption vacuoles and significantly larger follicular area than those from reference fields. Furthermore, testes of lizards from exposed locations had significantly larger seminiferous tubule diameters, significantly higher number of spermatogenic layers and displayed an up-regulation of thyroid hormone receptors when compared with lizards from reference areas. These findings strongly suggest that the complex mixture of herbicides that lizards are exposed to in agricultural areas have thyroid disrupting effects which ultimately affect the male reproductive system. Alachlor, which has demonstrated thyroid effects in mammals, may be largely responsible for the observed effects.

  2. Sands at Gusev Crater, Mars

    Science.gov (United States)

    Cabrol, Nathalie A.; Herkenhoff, Kenneth E.; Knoll, Andrew H.; Farmer, Jack D.; Arvidson, Raymond E.; Grin, E.A.; Li, Ron; Fenton, Lori; Cohen, B.; Bell, J.F.; Yingst, R. Aileen

    2014-01-01

    Processes, environments, and the energy associated with the transport and deposition of sand at Gusev Crater are characterized at the microscopic scale through the comparison of statistical moments for particle size and shape distributions. Bivariate and factor analyses define distinct textural groups at 51 sites along the traverse completed by the Spirit rover as it crossed the plains and went into the Columbia Hills. Fine-to-medium sand is ubiquitous in ripples and wind drifts. Most distributions show excess fine material, consistent with a predominance of wind erosion over the last 3.8 billion years. Negative skewness at West Valley is explained by the removal of fine sand during active erosion, or alternatively, by excess accumulation of coarse sand from a local source. The coarse to very coarse sand particles of ripple armors in the basaltic plains have a unique combination of size and shape. Their distribution display significant changes in their statistical moments within the ~400 m that separate the Columbia Memorial Station from Bonneville Crater. Results are consistent with aeolian and/or impact deposition, while the elongated and rounded shape of the grains forming the ripples, as well as their direction of origin, could point to Ma'adim Vallis as a possible source. For smaller particles on the traverse, our findings confirm that aeolian processes have dominated over impact and other processes to produce sands with the observed size and shape patterns across a spectrum of geologic (e.g., ripples and plains soils) and aerographic settings (e.g., wind shadows).

  3. Comparison of the effectiveness of phalanges vs. humeri and femurs to estimate lizard age with skeletochronology

    Energy Technology Data Exchange (ETDEWEB)

    Comas, M.; Reguera, S.; Zamora-Camacho, F.J.; Salvado, H.; Moreno-Rueda, G.

    2016-07-01

    Skeletochronology allows estimation of lizard age with a single capture (from a bone), making long–term monitoring unnecessary. Nevertheless, this method often involves the death of the animal to obtain the bone. We tested the reliability of skeletochronology of phalanges (which may be obtained without killing) by comparing the estimated age from femurs and humeri with the age estimated from phalanges. Our results show skeletochronology of phalanges is a reliable method to estimate age in lizards as cross–section readings from all bones studied presented a high correlation and repeatability regardless of the bone chosen. This approach provides an alternative to the killing of lizards for skeletochronology studies. (Author)

  4. Virulence of lizard malaria: the evolutionary ecology of an ancient parasite-host association.

    Science.gov (United States)

    Schall, J J

    1990-01-01

    The negative consequences of parasitic infection (virulence) were examined for two lizard malaria parasite-host associations: Plasmodium agamae and P. giganteum, parasites of the rainbow lizard, Agama agama, in Sierra Leone, West Africa; and P. mexicanum in the western fence lizard, Sceloporus occidentalis, in northern California. These malaria species vary greatly in their reproductive characteristics: P. agamae produces only 8 merozoites per schizont, P. giganteum yields over 100, and P. mexicanum an intermediate number. All three parasites appear to have had an ancient association with their host. In fence lizards, infection with malaria is associated with increased numbers of immature erythrocytes, decreased haemoglobin levels, decreased maximal oxygen consumption, and decreased running stamina. Not affected were numbers of erythrocytes, resting metabolic rate, and sprint running speed which is supported by anaerobic means in lizards. Infected male fence lizards had smaller testes, stored less fat in preparation for winter dormancy, were more often socially submissive and, unexpectedly, were more extravagantly coloured on the ventral surface (a sexually dimorphic trait) than non-infected males. Females also stored less fat and produced smaller clutches of eggs, a directly observed reduction in fitness. Infected fence lizards do not develop behavioural fevers. P. mexicanum appears to have broad thermal buffering abilities and thermal tolerance; the parasite's population growth was unaffected by experimental alterations in the lizard's body temperature. The data are less complete for A. agama, but infected lizards suffered similar haematological and physiological effects. Infected animals may be socially submissive because they appear to gather less insect prey, possibly a result of being forced into inferior territories. Infection does not reduce clutch size in rainbow lizards, but may lengthen the time between clutches. These results are compared with

  5. Intestinal parasites of unisexual and bisexual lizards Darevskia spp. (Lacertidae from Northeastern Anatolia

    Directory of Open Access Journals (Sweden)

    Roca V.

    2016-09-01

    Full Text Available Four bisexual and two unisexual species of the lizard genus Darevskia from northeastern Anatolia were searched for intestinal parasites in adult specimens. One cestode, Nematotaenia tarentolae, and two nematode species, Spauligodon saxicolae and Strongyloides darevskyi, were found, the latest identified as a Darevskia specialist. No major differences between host species were recorded. The very low infection rates and diversity result in depauperate helminth communities for all these lacertid lizards being the lowest among the Palaearctic saurians. Patterns of these helminth communities are compared with those observed in other lacertid lizards from Anatolia and Europe.

  6. The conservation status of the Saldanha-Langebaan lizard fauna

    Directory of Open Access Journals (Sweden)

    I.G. Cordes

    1996-01-01

    Full Text Available The conservation status of relic melanistic lizard species occurring in the Saldanha- Langebaan area has been investigated. A contact zone between one melanistic form and a closely related non-melanistic form has been examined in detail. Apart from melanis- tic populations of the girdled lizards, Cordylus niger and C. polywnus, a melanistic morphotype of the Cape legless skink, Acontias meleagris meleagris also occurs in the area. The taxonomic status of this morphotype needs to be investigated. At Mauritz Bay, north of Saldanha, the ranges of C niger and the non-melanistic C cordylus are in contact over a distance of approximately 240 m, with maximum overlap of 70 m. The melanistic populations of C. polyz.onus and A. m. meleagris have relatively large ranges in the Saldanha-Langebaan area and are not threatened by urban development. The C niger population, however, is fragmented into several subpopulations, and those in the Saldanha area, including the contact zone, will be affected if urban development is allowed to continue in the area. As relic populations of other cool-adapted, melanistic invertebrate and lower vertebrate species may also occur in the area, the key areas demarcated by C. niger should be preserved.

  7. Extended molecular phylogenetics and revised systematics of Malagasy scincine lizards.

    Science.gov (United States)

    Erens, Jesse; Miralles, Aurélien; Glaw, Frank; Chatrou, Lars W; Vences, Miguel

    2017-02-01

    Among the endemic biota of Madagascar, skinks are a diverse radiation of lizards that exhibit a striking ecomorphological variation, and could provide an interesting system to study body-form evolution in squamate reptiles. We provide a new phylogenetic hypothesis for Malagasy skinks of the subfamily Scincinae based on an extended molecular dataset comprising 8060bp from three mitochondrial and nine nuclear loci. Our analysis also increases taxon sampling of the genus Amphiglossus by including 16 out of 25 nominal species. Additionally, we examined whether the molecular phylogenetic patterns coincide with morphological differentiation in the species currently assigned to this genus. Various methods of inference recover a mostly strongly supported phylogeny with three main clades of Amphiglossus. However, relationships among these three clades and the limb-reduced genera Grandidierina, Voeltzkowia and Pygomeles remain uncertain. Supported by a variety of morphological differences (predominantly related to the degree of body elongation), but considering the remaining phylogenetic uncertainty, we propose a redefinition of Amphiglossus into three different genera (Amphiglossus sensu stricto, Flexiseps new genus, and Brachyseps new genus) to remove the non-monophyly of Amphiglossus sensu lato and to facilitate future studies on this fascinating group of lizards.

  8. Conserved sex chromosomes across adaptively radiated Anolis lizards.

    Science.gov (United States)

    Rovatsos, Michail; Altmanová, Marie; Pokorná, Martina; Kratochvíl, Lukáš

    2014-07-01

    Vertebrates possess diverse sex-determining systems, which differ in evolutionary stability among particular groups. It has been suggested that poikilotherms possess more frequent turnovers of sex chromosomes than homoiotherms, whose effective thermoregulation can prevent the emergence of the sex reversals induced by environmental temperature. Squamate reptiles used to be regarded as a group with an extensive variability in sex determination; however, we document how the rather old radiation of lizards from the genus Anolis, known for exceptional ecomorphological variability, was connected with stability in sex chromosomes. We found that 18 tested species, representing most of the phylogenetic diversity of the genus, share the gene content of their X chromosomes. Furthermore, we discovered homologous sex chromosomes in species of two genera (Sceloporus and Petrosaurus) from the family Phrynosomatidae, serving here as an outgroup to Anolis. We can conclude that the origin of sex chromosomes within iguanas largely predates the Anolis radiation and that the sex chromosomes of iguanas remained conserved for a significant part of their evolutionary history. Next to therian mammals and birds, Anolis lizards therefore represent another adaptively radiated amniote clade with conserved sex chromosomes. We argue that the evolutionary stability of sex-determining systems may reflect an advanced stage of differentiation of sex chromosomes rather than thermoregulation strategy.

  9. Age structured dynamical model for an endangered lizard Eulamprus leuraensis

    Science.gov (United States)

    Supriatna, A. K.; Rachmadani, Q.; Ilahi, F.; Anggriani, N.; Nuraini, N.

    2014-02-01

    The Blue Mountains Water Skink, Eulamprus leuraensis, is listed as an endangered species under the IUCN Red List. This lizard species has a typical characteristic of growth with a low fecundity. It is known that the offspring quality may decline with maternal age of the parents despite they can grow rapidly from neonatal size to adult size within two to three years. It is also believed that low adult survival rates and specialization on rare and fragmented type of habitat are the main cause leading to the endangered status of the lizard. A mathematical model with age structure for Eulamprus leuraensis, taking into account the variation of survival rate in each structure and the declining of offspring quality with respect to maternal age is considered here. Stable coexistence of non-trivial equilibriumis shown. It is also shown that an endangered status is due to combination oflow reproductive output and low rates of adult survival. Further, understanding the age structure within populations can facilitate efective management of the endangered species.

  10. DPTM simulation of aeolian sand ripple

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper. The difference between this method and the current methods is that the former can consider the three main factors relevant to the formation of natural aeolian sand ripples,which are the wind-blown sand flux above the sand bed formed by lots of sand particles with different di-ameters,the particle-bed collision and after it the rebound and ejection of sand particles in the sand bed,the saltation of high-speed sand particles and the creep of low-speed sand particles,respectively. The simulated aeolian sand ripple is close to the natural sand ripple not only in basic shape and characteristic,particle size segregation and stratigraphy,but also in formation stages. In addition,three important speeds can be obtained by this method,which are the propagation speed of the saturated aeolian sand ripple and the critical frictional wind speeds of emergence and disappearance of sand ripple.

  11. DPTM simulation of aeolian sand ripple

    Institute of Scientific and Technical Information of China (English)

    ZHENG XiaoJing; BO TianLi; XIE Li

    2008-01-01

    Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper.The difference between this method and the current methods is that the former can consider the three main factors relevant to the formation of natural aeolian sand ripples, which are the wind-blown sand flux above the sand bed formed by lots of sand particles with different di-ameters, the particle-bed collision and after it the rebound and ejection of sand particles in the sand bed, the saltation of high-speed sand particles and the creep of low-speed sand particles, respectively.The simulated aeolian sand ripple is close to the natural sand ripple not only in basic shape and characteristic, particle size segregation and stratigraphy, but also in formation stages.In addition, three important speeds can be obtained by this method, which are the propagation speed of the saturated aeolian sand ripple and the critical frictional wind speeds of emergence and disappearance of sand ripple.

  12. Dry reusing and wet reclaiming of used sodium silicate sand

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Based on the characteristics of used sodium silicate sand and the different use requirements for recycled sand, "dry reusing and wet reclaiming of used sodium silicate sand" is considered as the most suitable technique for the used sand. When the recycled sand is used as support sand, the used sand is only reused by dry process including breaking, screening, dust-removal, etc., and it is not necessary that the used sand is reclaimed with strongly rubbing and scraping method, but when the recycled sand is used as facing sand (or single sand), the used sand must be reclaimed by wet method for higher removal rate of the residual binders. The characteristics and the properties of the dry reused sand are compared with the wet reclaimed sand after combining the different use requirements of support sand and facing sand (or single sand), and above the most adaptive scheme has also been validated.

  13. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  14. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  15. Impact on sand and water

    NARCIS (Netherlands)

    Bergmann, R.P.H.M.

    2007-01-01

    In this thesis we investigate the impact of a body on sand and water. When a body impacts a free surface in the inertial regime the series of events is the following: On impact material is blown away in all directions and an impact cavity forms. Due to the hydrostatic pressure from the sides the cav

  16. Silo model tests with sand

    DEFF Research Database (Denmark)

    Munch-Andersen, Jørgen

    Tests have been carried out in a large silo model with Leighton Buzzard Sand. Normal pressures and shear stresses have been measured during tests carried out with inlet and outlet geometry. The filling method is a very important parameter for the strength of the mass and thereby the pressures...

  17. experimental studies of sand production from unconsolidated ...

    African Journals Online (AJOL)

    ES Obe

    Production of sand during oil and gas exploration causes severe operational prob- ... duction such as risk of well failure, erosion of pipelines and surface facilities, sand separa- tion and disposal ... ment, theoretical and numerical analysis have.

  18. UK silica sand resources for fracking

    OpenAIRE

    Mitchell, Clive

    2013-01-01

    UK silica sand resources for fracking Clive Mitchell, Industrial Minerals Specialist, British Geological Survey, Keyworth, Nottingham, NG12 5GG Email: Silica sand is high purity quartz sand that is mainly used for glass production, as foundry sand, in horticulture, leisure and other industrial uses. One specialist use is as a ‘proppant’ to enhance oil and gas recovery. This presentation will focus on this application, particularly for shale gas recovery where it is mo...

  19. Correlated amplitude fluctuations of spontaneous otoacoustic emissions in six lizard species

    NARCIS (Netherlands)

    van Dijk, P; Manley, GA; Gallo, L

    Spontaneous otoacoustic emissions were recorded from 17 lizard ears (six species: Gerrhosaurus major, Iguana iguana, Basiliscus vittatus, Tupinambis teguixin, Varanus exanthematicus, and Cordylus tropidosternum), The spectrum of each recording contained multiple spectral peaks. For each peak, the

  20. Correlated amplitude fluctuations of spontaneous otoacoustic emissions in six lizard species

    NARCIS (Netherlands)

    van Dijk, P; Manley, GA; Gallo, L

    1998-01-01

    Spontaneous otoacoustic emissions were recorded from 17 lizard ears (six species: Gerrhosaurus major, Iguana iguana, Basiliscus vittatus, Tupinambis teguixin, Varanus exanthematicus, and Cordylus tropidosternum), The spectrum of each recording contained multiple spectral peaks. For each peak, the en

  1. Six genetically distinct clades of Palola (Eunicidae, Annelida) from Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Schulze, Anja

    2015-09-18

    A total of 36 lots of Palola spp. (Eunicidae, Annelida) were collected during the Lizard Island Polychaete Workshop on Lizard Island, Great Barrier Reef, Queensland, Australia. Of these, 21 specimens were sequenced for a portion of the mitochondrial cytochrome c oxidase I gene. These sequences were analysed in conjunction with existing sequences of Palola spp. from other geographic regions. The samples from Lizard Island form six distinct clades, although none of them can clearly be assigned to any of the nominal species. Four of the six Lizard Island clades fall into species group A and the remaining two into species group B (which also includes the type species, Palola viridis). All sequenced specimens were characterized morphologically as far as possible and a dichotomous key was assembled. Based on this key, the remaining samples were identified as belonging to one of the clades.

  2. Thermal biology of Phymaturus lizards: evolutionary constraints or lack of environmental variation?

    Science.gov (United States)

    Cruz, Felix B; Belver, Luciana; Acosta, Juan C; Villavicencio, Héctor J; Blanco, Graciela; Cánovas, Maria G

    2009-01-01

    Several aspects of the biology of Phymaturus lizards including their herbivorous diet, specialized microhabitat use, and viviparous reproductive mode are highly conserved within the group. Here, we explore two aspects of Phymaturus thermal biology and test for the co-evolution among aspects of the thermal biology in these lizards, such as thermal preferenda and critical temperatures. Secondly, we explore correlations among variation in thermal biology with elevation and latitude. To do so, we used phylogenetically based comparative analyses (PCM) together with conventional statistics. Our results show that thermal biology for Phymaturus is conservative and our data do not suggest the co-evolution of thermal variables. Moreover, we detected low levels of variation in the thermal parameters studied, and no clear relationships between climatic and thermal variables. As a significant association between climatic and thermal variables could be demonstrated for a set of syntopic Liolaemus lizards, we suggest that thermal biology in Phymaturus lizards may be evolutionarily or ecologically constrained.

  3. Hepatozoon kisrae n. sp. infecting the lizard Agama stellio is transmitted by the tick Hyalomma cf. aegyptium

    Directory of Open Access Journals (Sweden)

    Paperna I.

    2002-03-01

    Full Text Available Hepatozoon kisrae n. sp. was found infecting a starred lizard at a site in southeastern Samaria, Palestine. These lizards were also hosts to the ixodid tick Hyolomma cf. aegyptium, which was demonstrated to be the vector of this hemogregarine. Hepatozoon and tick infections occurred in lizards within a very restricted locality; at a second site, nearby, ticks occurred without Hepatozoon infection. Micro- and macromeronts occurred mainly in the lungs, while cyst-like merogonic stages, mainly dizoic, occurred in the liver. Mature intraerythrocytic gametocytes were stout and encapsulated. Development from oocysts to sporocysts took place in the tick hemocoel, and was examined by transmission electron microscopy. Lizards were successfully infected when fed on sporocyst-infected ticks or viscera of infected lizards. Ticks become infected when fed on infected lizards; sporogony was complete when the ticks reached adult stage, over 40 days after initial attachment.

  4. Treating tar sands formations with karsted zones

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J. (Bellaire, TX); Karanikas, John Michael (Houston, TX)

    2010-03-09

    Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.

  5. Soft X-Ray Observations of a Complete Sample of X-Ray--selected BL Lacertae Objects

    Science.gov (United States)

    Perlman, Eric S.; Stocke, John T.; Wang, Q. Daniel; Morris, Simon L.

    1996-01-01

    We present the results of ROSAT PSPC observations of the X-ray selected BL Lacertae objects (XBLs) in the complete Einstein Extended Medium Sensitivity Survey (EM MS) sample. None of the objects is resolved in their respective PSPC images, but all are easily detected. All BL Lac objects in this sample are well-fitted by single power laws. Their X-ray spectra exhibit a variety of spectral slopes, with best-fit energy power-law spectral indices between α = 0.5-2.3. The PSPC spectra of this sample are slightly steeper than those typical of flat ratio-spectrum quasars. Because almost all of the individual PSPC spectral indices are equal to or slightly steeper than the overall optical to X-ray spectral indices for these same objects, we infer that BL Lac soft X-ray continua are dominated by steep-spectrum synchrotron radiation from a broad X-ray jet, rather than flat-spectrum inverse Compton radiation linked to the narrower radio/millimeter jet. The softness of the X-ray spectra of these XBLs revives the possibility proposed by Guilbert, Fabian, & McCray (1983) that BL Lac objects are lineless because the circumnuclear gas cannot be heated sufficiently to permit two stable gas phases, the cooler of which would comprise the broad emission-line clouds. Because unified schemes predict that hard self-Compton radiation is beamed only into a small solid angle in BL Lac objects, the steep-spectrum synchrotron tail controls the temperature of the circumnuclear gas at r ≤ 1018 cm and prevents broad-line cloud formation. We use these new ROSAT data to recalculate the X-ray luminosity function and cosmological evolution of the complete EMSS sample by determining accurate K-corrections for the sample and estimating the effects of variability and the possibility of incompleteness in the sample. Our analysis confirms that XBLs are evolving "negatively," opposite in sense to quasars, with Ve/Va = 0.331±0.060. The statistically significant difference between the values for X

  6. Temperature has species-specific effects on corticosterone in alligator lizards.

    Science.gov (United States)

    Telemeco, Rory S; Addis, Elizabeth A

    2014-09-15

    In response to conditions that threaten homeostasis and/or life, vertebrates generally increase production of glucocorticoid hormones, such as corticosterone (CORT), which induces an emergency physiological state referred to as the stress response. Given that extreme temperatures pose a threat to performance and survival, glucocorticoid upregulation might be an important component of a vertebrate ectotherm's response to extreme thermal conditions. To address this hypothesis, we experimentally examined the effects of body temperature (10, 20, 28, and 35°C; 5-h exposure) on CORT in two congeneric species of lizard naturally exposed to different thermal environments, northern and southern alligator lizards (Elgaria coerulea and Elgaria multicarinata, respectively). In both species, CORT was similarly elevated at medium and high temperatures (28 and 35°C, respectively), but CORT was only elevated at low temperatures (10°C) in southern alligator lizards. We also examined CORT before and after adrenocorticotrophic hormone (ACTH) challenge. In both species, ACTH induced higher CORT levels than any temperature, suggesting that these animals could respond to further stressors at all experimental temperatures. Finally, we compared our laboratory results to measurements of CORT in field-active southern alligator lizards. Plasma CORT concentrations from our laboratory experiment had the same mean and less variance than the field lizards, suggesting that our laboratory lizards displayed CORT within natural levels. Our results demonstrate that body temperature directly affects CORT in alligator lizards. Moreover, the CORT response of these lizards appears to be adapted to their respective thermal environments. Species-specific differences in the thermal CORT response might be common in vertebrate ectotherms and have implications for species' biogeography and responses to climate change.

  7. Influence of stress on gonadotrophin induced testicular recrudescence in the lizard Mabuya Carinata.

    Science.gov (United States)

    Yajurvedi, H N; Menon, Sneha

    2005-07-01

    Administration (ip) of FSH (10 IU/0.1 ml distilled water (dw)/lizard/alternate days/30 days) to adult male lizards, Mabuya carinata, during the early recrudescence phase of the reproductive cycle caused activation of spermatogenic and steroidogenic activity of the testis, as shown by a significant increase in mean number of spermatogonia, primary spermatocytes and spermatids, and serum levels of testosterone, as compared to initial controls. In addition, there were abundant spermatozoa in the lumen of the seminiferous tubules. Interestingly, administration of a similar dosage of FSH to lizards exposed to stressors (handling, chasing, and noise randomly applied, five times a day for 30 days) resulted in a significant increase in mean number of spermatogonia and primary spermatocytes over initial control values, whereas the number of secondary spermatocytes and spermatids and serum levels of testosterone did not significantly differ from those of initial controls, and were significantly lower than FSH treated normal lizards. Further, spermatozoa were infrequently found in the seminiferous tubules of these lizards. Treatment controls (receiving 0.1 ml dw/lizard/alternate days for 30 days) did not show significant variation in mean number of spermatogonia, spermatocytes and spermatids, and serum levels of testosterone from initial controls. Another group of lizards was exposed to stressors and did not receive FSH. These lizards showed a significant decrease in mean number of secondary spermatocytes compared to treatment controls and all other parameters did not significantly differ from those of both control groups. The results reveal that gonadotrophin-induced spermatogonial proliferation occurs under stressful conditions, whereas progress of spermatogenesis beyond primary spermatocyte stage is impaired due to inhibition (under stress) of gonadotrophin induced steroidogenic activity in M. carinata.

  8. Checklist of the lizards of Togo (West Africa), with comments on systematics, distribution, ecology, and conservation

    OpenAIRE

    Hoinsoude Segniagbeto, G.; Trape, Jean-François; Afiademanyo, K. M.; Rodel, M. O.; Ohler, A.; Dubois, A.; David, P.; Meirte, D.; Glitho, I. A.; Petrozzi, F.; L. Luiselli

    2015-01-01

    The lizard fauna of Togo, a country situated within a natural gap in the rainforest zone of West Africa, is reviewed and updated. In this article, we summarize all available data on the distribution, ecology, and conservation status of the 43 lizard species of Togo. Species richness is uneven between vegetation zones. The submontane forest (ecological zone IV), despite being the smallest, houses the greatest number of species (n = 27), followed by dry forest (ecological zone II, n = 21). Curr...

  9. Are lizards feeling the heat?: a tale of ecology and evolution under two temperatures

    OpenAIRE

    Meiri, Shai; Bauer, Aaron M.; Chirio, Laurent; Colli, Guarino R; Das, Indraneil; Doan, Tiffany M.; Feldman, Anat; Herrera, Fernando-Castro; Novosolov, Maria; Pafilis, Panayiotis; Pincheira-Donoso, Daniel; Powney, Gary; Torres-Carvajal, Omar; Uetz, Peter; Van Damme, Raoul

    2013-01-01

    Aim: Temperature influences most components of animal ecology and life history – but what kind of temperature? Physiologists usually examine the influence of body temperatures, while biogeographers and macroecologists tend to focus on environmental temperatures. We aim to examine the relationship between these two measures, to determine the factors that affect lizard body temperatures and to test the effect of both temperature measures on lizard life history. Location: World-wide. Methods: We...

  10. Preliminary observations on the reproductive cycle of female Tegu lizards (Tupinambis teguizin)

    OpenAIRE

    Yanosky, Ángel Alberto; Mercolli, Claudia

    1991-01-01

    The black tegu lizard, Tupinambis teguixin (Linnaeus 1758) is a common element in the wild all throughout Southamerica except for Chile. This teiid lizard was outstood by earlier travellers such as Sir Charles Waterton who reported for the first time about the delicate food, resembling chicken flesh and frequently consumed by local natives. Despite its relative abundance and both the intense economical and social importance of tegus, as well as its situation in the food web, the reproductive ...

  11. The peak of thermoregulation effectiveness: Thermal biology of the Pyrenean rock lizard, Iberolacerta bonnali (Squamata, Lacertidae).

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-02-01

    We studied, at 2200m altitude, the thermal biology of the Pyrenean rock lizard, Iberolacerta bonnali, in the glacial cirque of Cotatuero (National Park of Ordesa, Huesca, Spain). The preferred thermal range (PTR) of I. bonnali indicates that it is a cold-adapted ectotherm with a narrow PTR (29.20-32.77°C). However, its PTR (3.57°C) is twice as wide as other Iberolacerta lizards, which may be explained by its broader historical distribution. The studied area is formed by a mosaic of microhabitats which offer different operative temperatures, so that lizards have, throughout their entire daily period of activity, the opportunity to choose the most thermally suitable substrates. I. bonnali achieves an effectiveness of thermoregulation of 0.95, which makes it the highest value found to date among the Lacertidae, and one of the highest among lizards. Their relatively wide distribution, their wider PTR, and their excellent ability of thermoregulation, would make I. bonnali lizards less vulnerable to climate change than other species of Iberolacerta. Thanks to its difficult access, the studied area is not visited by a large number of tourists, as are other areas of the National Park. Thus, it is a key area for the conservation of the Pyrenean rock lizard. By shuttling between suitable microhabitats, lizards achieve suitable body temperatures during all day. However, such thermally suitable microhabitats should vary in other traits than thermal quality, such as prey availability or predation risk. Hence, it seems that these not-thermal traits are not constraining habitat selection and thermoregulation in this population. Therefore, future research in this population may study the causes that would lead lizards to prioritize thermoregulation to such extent in this population. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Cytogenetic and molecular characterization of lacertid lizard species from the Iberian Peninsula

    OpenAIRE

    Rojo Oróns, Verónica

    2016-01-01

    [Abstract] Reptiles, with their great diversity of sex-determining systems, have long been regarded as a model group for studying the evolution of sex determination and sex chromosomes. They also hold a key phylogenetic position to elucidate the organization and evolution of amniote genomes. This PhD thesis aims to contribute to this understanding by investigating sex chromosomes and karyotype evolution in lacertid lizards, with a focus on rock lizard species (genus Iberolac...

  13. On the water lapping of felines and the water running of lizards: A unifying physical perspective

    OpenAIRE

    Aristoff, Jeffrey M.; Stocker, Roman; Reis, Pedro M.; Jung, Sunghwan

    2011-01-01

    We consider two biological phenomena taking place at the air-water interface: the water lapping of felines and the water running of lizards. Although seemingly disparate motions, we show that they are intimately linked by their underlying hydrodynamics and belong to a broader class of processes called Froude mechanisms. We describe how both felines and lizards exploit inertia to defeat gravity, and discuss water lapping and water running in the broader context of water exit and water entry, r...

  14. On the water lapping of felines and the water running of lizards: A unifying physical perspective

    OpenAIRE

    Aristoff, Jeffrey M.; Stocker, Roman; Reis, Pedro M.; Jung, Sunghwan

    2011-01-01

    We consider two biological phenomena taking place at the air-water interface: the water lapping of felines and the water running of lizards. Although seemingly disparate motions, we show that they are intimately linked by their underlying hydrodynamics and belong to a broader class of processes called Froude mechanisms. We describe how both felines and lizards exploit inertia to defeat gravity, and discuss water lapping and water running in the broader context of water exit and water entry, r...

  15. Sand Waves. Report 1. Sand Wave Shoaling in Navigation Channels

    Science.gov (United States)

    1992-09-01

    heights range from 0.8 m in the Minas Basin, Bay of Fundy (Dalrymple 1984) to 6.0 m in the Bahia Blanca Estuary, Argentina (Aliotta and Perillo 1987...26 PART IV: SITE-SPECIFIC SAND WAVE SHOALING PROBLEMS .. ........ 30 Columbia River Navigation Channel ........ ............... .. 30 Panama ...problem location discussed in this report is at St. Andrew Bay near Panama City, Florida. A relatively short section of the jettied inlet channel requires

  16. Recurrent evolution of herbivory in small, cold-climate lizards: Breaking the ecophysiological rules of reptilian herbivory

    OpenAIRE

    Espinoza, Robert E.; Wiens, John J.; Tracy, C. Richard

    2004-01-01

    Herbivory has evolved in many groups of vertebrates, but it is rare among both extinct and extant nonavian reptiles. Among squamate reptiles, (lizards, snakes, and their relatives), 7,800 species are considered to be herbivorous, and herbivory is restricted to lizards. Here, we show that within a group of South American lizards (Liolaemidae, ≈170 species), herbivory has evolved more frequently than in all other squamates combined and at a rate estimated to be >65 times faster. Furthermore, in...

  17. Fossilized Venom: The Unusually Conserved Venom Profiles of Heloderma Species (Beaded Lizards and Gila Monsters

    Directory of Open Access Journals (Sweden)

    Ivan Koludarov

    2014-12-01

    Full Text Available Research into snake venoms has revealed extensive variation at all taxonomic levels. Lizard venoms, however, have received scant research attention in general, and no studies of intraclade variation in lizard venom composition have been attempted to date. Despite their iconic status and proven usefulness in drug design and discovery, highly venomous helodermatid lizards (gila monsters and beaded lizards have remained neglected by toxinological research. Proteomic comparisons of venoms of three helodermatid lizards in this study has unravelled an unusual similarity in venom-composition, despite the long evolutionary time (~30 million years separating H. suspectum from the other two species included in this study (H. exasperatum and H. horridum. Moreover, several genes encoding the major helodermatid toxins appeared to be extremely well-conserved under the influence of negative selection (but with these results regarded as preliminary due to the scarcity of available sequences. While the feeding ecologies of all species of helodermatid lizard are broadly similar, there are significant morphological differences between species, which impact upon relative niche occupation.

  18. Detection of Campylobacter jejuni in Lizard Faeces from Central Australia Using Quantitative PCR

    Directory of Open Access Journals (Sweden)

    Harriet Whiley

    2016-12-01

    Full Text Available Worldwide, Campylobacter is a significant cause of gastrointestinal illness. It is predominately considered a foodborne pathogen, with human exposure via non-food transmission routes generally overlooked. Current literature has been exploring environmental reservoirs of campylobacteriosis including potential wildlife reservoirs. Given the close proximity between lizards and human habitats in Central Australia, this study examined the presence of Campylobacter jejuni from lizard faeces collected from this region. Of the 51 samples collected, 17 (33% (this included 14/46 (30% wild and 3/5 (60% captive lizard samples were positive for C. jejuni using quantitative PCR (qPCR. This was the first study to investigate the presence of C. jejuni in Australian lizards. This has public health implications regarding the risk of campylobacteriosis from handling of pet reptiles and through cross-contamination or contact with wild lizard faeces. Additionally this has implication for horizontal transmission via lizards of C. jejuni to food production farms. Further research is needed on this environmental reservoir and potential transmission routes to reduce the risk to public health.

  19. Incidence, causes and consequences of pregnancy failure in viviparous lizards: implications for research and conservation settings.

    Science.gov (United States)

    Hare, Kelly M; Cree, Alison

    2010-01-01

    Research on the causes of pregnancy failure in vertebrates has historically been mammal-focussed. However, live-birth (viviparity) has evolved multiple times, and is present in all other vertebrate taxa except Aves and Agnatha. Viviparous lizards (O. Squamata, excluding snakes and amphisbaenians) provide a valuable experimental group when studying major evolutionary events and some are also species of high conservation value. Consequently, both researchers and herpetoculturists often require high reproductive output from captive-held lizards. We reviewed the literature to determine potential or known causes of pregnancy failure for captive lizards. Pregnancy success across species averages approximately 86%, but varies extensively and does not appear to be related to embryonic stage when brought into captivity or level of placentation. Causes of pregnancy failure also vary among species, but correct thermal environments are vital to success, and providing adequate nutrition before vitellogenesis increases the number of viable offspring. A coordinated sequence of hormonal changes involving both pro-pregnancy and pro-labour factors is important for successful pregnancies, although uncertainty remains around the maternal concentrations of corticosterone that allow successful development. Several research areas commonly studied in mammals have yet to be explored or fully addressed in pregnant lizards, including impacts of toxins, parasites, UV light and nutritional quality. As viviparity has evolved over 100 times in lizards, and many different levels of placentation exist, pregnant lizards provide valuable models for studies in ecology and evolution and offer a useful comparison for studies on other viviparous vertebrates.

  20. Fossilized venom: the unusually conserved venom profiles of Heloderma species (beaded lizards and gila monsters).

    Science.gov (United States)

    Koludarov, Ivan; Jackson, Timothy N W; Sunagar, Kartik; Nouwens, Amanda; Hendrikx, Iwan; Fry, Bryan G

    2014-12-22

    Research into snake venoms has revealed extensive variation at all taxonomic levels. Lizard venoms, however, have received scant research attention in general, and no studies of intraclade variation in lizard venom composition have been attempted to date. Despite their iconic status and proven usefulness in drug design and discovery, highly venomous helodermatid lizards (gila monsters and beaded lizards) have remained neglected by toxinological research. Proteomic comparisons of venoms of three helodermatid lizards in this study has unravelled an unusual similarity in venom-composition, despite the long evolutionary time (~30 million years) separating H. suspectum from the other two species included in this study (H. exasperatum and H. horridum). Moreover, several genes encoding the major helodermatid toxins appeared to be extremely well-conserved under the influence of negative selection (but with these results regarded as preliminary due to the scarcity of available sequences). While the feeding ecologies of all species of helodermatid lizard are broadly similar, there are significant morphological differences between species, which impact upon relative niche occupation.

  1. Coloration affects heating and cooling in three color morphs of the Australian bluetongue lizard, Tiliqua scincoides.

    Science.gov (United States)

    Geen, Michael R S; Johnston, Gregory R

    2014-07-01

    The color-mediated thermoregulation hypothesis predicts that dark body color (low reflectance) allows organisms to gain heat more efficiently than does pale coloration (high reflectance). This prediction is intuitive and widely assumed to be true, but has poor empirical support. We used rare, captive-bred, mutant melanistic, albino and wild-type Australian bluetongue lizards, Tiliqua scincoides to measure the effects of skin reflectance on the heating and cooling rates. We measured heating under an artificial radiant heat source and cooling rates in an ice-cooled box using live lizards in a room with still air. The effect of skin reflectance on heat transfer was clear, despite the substantial influence of body size. Melanistic T. scincoides showed low reflectance and gained heat faster than highly reflective albinos. Melanistic lizards also lost heat faster than albinos. Wild-type lizards were intermediate in reflectance, gained heat at rates indistinguishable from melanistic lizards, and lost heat at rates indistinguishable from albino lizards. This study system allowed us to control for variables that were confounded in other studies and may explain the inconsistent support for the color-mediated thermoregulation hypothesis. Our results provide clear evidence that skin reflectance influences the rate of heating and cooling in ectotherms.

  2. The use of a lacertid lizard as a model for reptile ecotoxicology studies: part 2--biomarkers of exposure and toxicity among pesticide exposed lizards.

    Science.gov (United States)

    Amaral, Maria José; Bicho, Rita C; Carretero, Miguel A; Sanchez-Hernandez, Juan C; Faustino, Augusto M R; Soares, Amadeu M V M; Mann, Reinier M

    2012-05-01

    As part of a wider study examining the impacts of corn pesticides on lacertid lizards in north-western Portugal, we examined various physiological, biochemical, and histological biomarkers of exposure and effect among field populations of Podarcis bocagei. Biomarkers included body condition index, standard metabolic rate, locomotor performance, parasitization, glutathione oxidative pathways and related enzyme activity, lipid peroxidation and liver and testis histology. Few of the various biomarkers investigated provided statistically significant evidence of toxic effect. However, using a weight of evidence approach, we conclude that pesticides are affecting lizards living in the vicinity of pesticide exposed corn agriculture sites. Lizards from these locations present a profile of animals under metabolic stress with reduced condition indices, increased standard metabolic rate, lower incidence of hepatocyte vacuolation, altered iron metabolism, increased activation of GSH oxidation pathways, and even increased prevalence of hemoparasites.

  3. Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard: e0138016

    National Research Council Canada - National Science Library

    Maximilian Drakeley; Oriol Lapiedra; Jason J Kolbe

    2015-01-01

    .... We presented male lizards with foraging opportunities to test how the presence of conspecifics, predation-risk perception, the abundance of food, and interactions among these factors determines...

  4. A telencephalospinal projection in the Tegu lizard (Tupinambis teguixin).

    Science.gov (United States)

    Follett, K A

    1989-09-04

    Tegu lizards (Tupinambis teguixin) were studied to determine the presence of a homologue of the mammalian corticospinal tract. The sources of telencephalic efferent projections to the spinal cord were determined by evaluating the localization of retrogradely transported horseradish peroxidase applied in the cervical spinal cord. Labeled cells were present in subtelencephalic sites reported previously by other authors and, in addition, were found in the principal sensory and motor nuclei of the trigeminal nerve and in the nucleus of the posterior commissure. A telencephalospinal projection was identified, originating in the ventral caudal telencephalon. Histochemical staining revealed a high concentration of acetylcholinesterase in cells and neuropil in the same area. This tract is suggested to be homologous to the mammalian amygdalospinal tract. No reptilian homologue of the corticospinal tract was identified.

  5. Syllidae (Annelida: Phyllodocida) from Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Aguado, M Teresa; Murray, Anna; Hutchings, Pat

    2015-09-18

    Thirty species of the family Syllidae (Annelida, Phyllodocida) from Lizard Island have been identified. Three subfamilies (Eusyllinae, Exogoninae and Syllinae) are represented, as well as the currently unassigned genera Amblyosyllis and Westheidesyllis. The genus Trypanobia (Imajima & Hartman 1964), formerly considered a subgenus of Trypanosyllis, is elevated to genus rank. Seventeen species are new reports for Queensland and two are new species. Odontosyllis robustus n. sp. is characterized by a robust body and distinct colour pattern in live specimens consisting of lateral reddish-brown pigmentation on several segments, and bidentate, short and distally broad falcigers. Trypanobia cryptica n. sp. is found in association with sponges and characterized by a distinctive bright red colouration in live specimens, and one kind of simple chaeta with a short basal spur.

  6. A new filaria of a lizard transmitted by sandflies

    Directory of Open Access Journals (Sweden)

    Odile Bain

    1992-01-01

    Full Text Available A description is given of Madathamugadia wanjii n. sp., a Splendidofilariinae parasite of the gecko Ptyodactylus hasselquistii, on the west bank of the River Jordan and of its life cycle in Phlebotomus duboscqi. The new species is close to M. ivaschkini (Annaev, 1976 n. comb., of Turkmenistan, wich is also transmitted by sandflies (Reznik, 1982. The genus Madathamugadia is now comprised of four species, two from Madagascar and two from the Mediterranean sub-region; it differs from the genus Thamugadia by the presence of a double row of papillae anterior to the cloaca of the male. The larval characters of Splendidofilarinae of lizards confirm the affinity of these parasites to the Splendidofilarinae of birds (Chandlerella and Splendidofilaria; the first group could have arisen from the second by "captures" wich could have occurred in several places.

  7. Mitochondrial DNA recombination in a free-ranging Australian lizard.

    Science.gov (United States)

    Ujvari, Beata; Dowton, Mark; Madsen, Thomas

    2007-04-22

    Mitochondrial DNA (mtDNA) is the traditional workhorse for reconstructing evolutionary events. The frequent use of mtDNA in such analyses derives from the apparent simplicity of its inheritance: maternal and lacking bi-parental recombination. However, in hybrid zones, the reproductive barriers are often not completely developed, resulting in the breakdown of male mitochondrial elimination mechanisms, leading to leakage of paternal mitochondria and transient heteroplasmy, resulting in an increased possibility of recombination. Despite the widespread occurrence of heteroplasmy and the presence of the molecular machinery necessary for recombination, we know of no documented example of recombination of mtDNA in any terrestrial wild vertebrate population. By sequencing the entire mitochondrial genome (16761bp), we present evidence for mitochondrial recombination in the hybrid zone of two mitochondrial haplotypes in the Australian frillneck lizard (Chlamydosaurus kingii).

  8. METHOD OF PROCESSING MONAZITE SAND

    Science.gov (United States)

    Welt, M.A.; Smutz, M.

    1958-08-26

    A process is described for recovering thorium, uranium, and rare earth values from monazite sand. The monazite sand is first digested with sulfuric acid and the resulting "monazite sulfate" solution is adjusted to a pH of between 0.4 and 3.0, and oxalate anions are added causing precipitation of the thorium and the rare earths as the oxalates. The oxalate precipitate is separated from the uranium containing supernatant solution, and is dried and calcined to the oxides. The thorium and rare earth oxides are then dissolved in nitric acid and the solution is contacted with tribntyl phosphate whereby an organic extract phase containing the cerium and thorium values is obtained, together with an aqueous raffinate containing the other rare earth values. The organic phase is then separated from the aqueous raffinate and the cerium and thorium are back extracted with an aqueous medium.

  9. Granular resistive force theory explains the neuromechanical phase lag during sand-swimming

    Science.gov (United States)

    Ding, Yang; Sharpe, Sarah; Goldman, Daniel

    2012-11-01

    Undulatory locomotion is a common gait used by a diversity of animals in a range of environments. This mode of locomotion is characterized by the propagation of a traveling wave of body bending, which propels the animal in the opposite direction of the wave. Previous studies of undulatory locomotion in fluids, on land, and even within sand revealed that the wave of muscle activation progresses faster than the traveling wave of curvature. This leads to an increasing phase lag between activation and curvature at more posterior segments, known as the neuromechanical phase lag. In this study, we compare biological measurements of phase lag during the sand-swimming of the sandfish lizard to predictions of a simple model of undulatory swimming that consists of prescribed kinematics and granular resistive forces. The neuromechanical phase lag measured using electromyography (EMG) quantitatively matches the predicted phase lag between the local body curvature and torque exerted by granular resistive forces. Two effects are responsible for the phase lag in this system: the yaw motion of the body and different integration length over a traveling force pattern for different positions along the body.

  10. Slithering on sand: kinematics and controls for success on granular media

    Science.gov (United States)

    Schiebel, Perrin E.; Zhang, Tingnan; Dai, Jin; Gong, Chaohui; Yu, Miao; Astley, Henry C.; Travers, Matthew; Choset, Howie; Goldman, Daniel I.

    Previously, we studied the subsurfacelocomotion of undulatory sand-swimming snakes and lizards; using empirical drag response of GM to subsurface intrusion of simple objects allowed us to develop a granular resistive force theory (RFT) to model the locomotion and predict optimal movement patterns. However, our knowledge of the physics of GM at the surface is limited; this makes it impossible to determine how the desert-dwelling snake C. occipitalis moves effectively (0.45 +/-0.04 bodylengths/sec) on the surface of sand .We combine organism biomechanics studies, GM drag experiments, RFT calculations and tests of a physical model (a snake-like robot), to reveal how multiple factors acting together contribute to slithering on sandy surfaces. These include the kinematics--targeting an ideal waveform which maximizes speed while minimizing joint-level torque, the ability to modulate ground interactions by lifting body segments, and the properties of the GM. Based on the sensitive nature of the relationship between these factors, we hypothesize that having an element of force-based control, where the waveform is modulated in response to the forces acting between the body and the environment, is necessary for successful locomotion on yielding substrates.

  11. Oogenesis in the viviparous matrotrophic lizard Mabuya brachypoda.

    Science.gov (United States)

    Hernández-Franyutti, Arlette; Uribe Aranzábal, Mari Carmen; Guillette, Louis J

    2005-08-01

    Oogenesis in the lizard Mabuya brachypoda is seasonal, with oogenesis initiated during May-June and ovulation occurring during July-August. This species ovulates an egg that is microlecithal, having very small yolk stores. The preovulatory oocyte attains a maximum diameter of 0.9-1.3 mm. Two elongated germinal beds, formed by germinal epithelia containing oogonia, early oocytes, and somatic cells, are found on the dorsal surface of each ovary. Although microlecithal eggs are ovulated in this species, oogenesis is characterized by both previtellogenic and vitellogenic stages. During early previtellogenesis, the nucleus of the oocyte contains lampbrush chromosomes, whereas the ooplasm stains lightly with a perinuclear yolk nucleus. During late previtellogenesis the ooplasm displays basophilic staining with fine granular material composed of irregularly distributed bundles of thin fibers. A well-defined zona pellucida is also observed. The granulosa, initially composed of a single layer of squamous cells during early previtellogenesis, becomes multilayered and polymorphic. As with other squamate reptiles, the granulosa at this stage is formed by three cell types: small, intermediate, and large or pyriform cells. As vitellogenesis progresses the oocyte displays abundant vacuoles and small, but scarce, yolk platelets at the periphery of the oocyte. The zona pellucida attains its maximum thickness during late oogenesis, a period when the granulosa is again reduced to a single layer of squamous cells. The vitellogenic process observed in M. brachypoda corresponds with the earliest vitellogenic stages seen in other viviparous lizard species with larger oocytes. The various species of the genus Mabuya provided us with important models to understand a major transition in the evolution of viviparity, the development of a microlecithal egg.

  12. Characterization of sand lenses embedded in tills

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Klint, K.E.S.; Nilsson, B.

    2012-01-01

    of the various types of sand lenses is discussed, primarily in relation to the depositional and glaciotectonic processes they underwent. Detailed characterization of sand lenses facilitates such interpretations. Finally, the observations are linked to a more general overview of the distribution of sand lenses......Tills dominate large parts of the superficial sediments on the Northern hemisphere. These glacial diamictons are extremely heterogeneous and riddled with fractures and lenses of sand or gravel. The frequency and geometry of sand lenses within tills are strongly linked to glaciodynamic processes...... occurring in various glacial environments. This study specifically focuses on the appearance and spatial distribution of sand lenses in tills. It introduces a methodology on how to measure and characterize sand lenses in the field with regard to size, shape and degree of deformation. A set of geometric...

  13. A compact topology for sand automata

    CERN Document Server

    Dennunzio, Alberto; Masson, Benoît

    2008-01-01

    In this paper, we exhibit a strong relation between the sand automata configuration space and the cellular automata configuration space. This relation induces a compact topology for sand automata, and a new context in which sand automata are homeomorphic to cellular automata acting on a specific subshift. We show that the existing topological results for sand automata, including the Hedlund-like representation theorem, still hold. In this context, we give a characterization of the cellular automata which are sand automata, and study some dynamical behaviors such as equicontinuity. Furthermore, we deal with the nilpotency. We show that the classical definition is not meaningful for sand automata. Then, we introduce a suitable new notion of nilpotency for sand automata. Finally, we prove that this simple dynamical behavior is undecidable.

  14. Rheological Characterization of Green Sand Flow

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hovad, Emil

    2016-01-01

    The main aim of this paper is to characterize experimentally the flow behaviour of the green sand that is used for casting of sand moulds. After the sand casting process is performed, the sand moulds are used for metal castings. The rheological properties of the green sand is important to quantify...... module for characterizing granular materials. The new module enables viscosity measurements of the green sand as function of the shear rate at different flow rates, i.e. 0, 2, 4, 6, 8, 10, 12 and 15 L/min. The results show generally that the viscosity decreases with both the shear- and flow rate....... In addition, the measurements show that the green sand flow follows a shear-thinning behaviour even after the full fluidization point....

  15. Silo model tests with sand

    DEFF Research Database (Denmark)

    Munch-Andersen, Jørgen

    Tests have been carried out in a large silo model with Leighton Buzzard Sand. Normal pressures and shear stresses have been measured during tests carried out with inlet and outlet geometry. The filling method is a very important parameter for the strength of the mass and thereby the pressures...... as well as the flow pattern during discharge of the silo. During discharge a mixed flow pattern has been identified...

  16. Formation of Craters in Sand

    Directory of Open Access Journals (Sweden)

    Vanissra Boonyaleepun

    2007-06-01

    Full Text Available The diameter of craters formed by spheres of varying mass dropped into sand at low speed was studied. The relationship between the diameter of the crater formed and the kinetic energy of the projectile at impact was found to be of the same general form as that for planetary meteor craters. The relationship is shown to be a power law with exponent 0.17.

  17. Formation of Craters in Sand

    Directory of Open Access Journals (Sweden)

    Vanissra Boonyaleepun

    2007-06-01

    Full Text Available The diameter of craters formed by spheres of varying mass dropped into sand at low speed was studied. The relationship between the diameter of the crater formed and the kinetic energy of the projectile at impact was found to be of the same general form as that for planetary meteor craters. The relationship is shown to be a power law with exponent 0.17

  18. Thermal Properties of oil sand

    Science.gov (United States)

    LEE, Y.; Lee, H.; Kwon, Y.; Kim, J.

    2013-12-01

    Thermal recovery methods such as Cyclic Steam Injection or Steam Assisted Gravity Drainage (SAGD) are the effective methods for producing heavy oil or bitumen. In any thermal recovery methods, thermal properties (e.g., thermal conductivity, thermal diffusivity, and volumetric heat capacity) are closely related to the formation and expansion of steam chamber within a reservoir, which is key factors to control efficiency of thermal recovery. However, thermal properties of heavy oil or bitumen have not been well-studied despite their importance in thermal recovery methods. We measured thermal conductivity, thermal diffusivity, and volumetric heat capacity of 43 oil sand samples from Athabasca, Canada, using a transient thermal property measurement instrument. Thermal conductivity of 43 oil sand samples varies from 0.74 W/mK to 1.57 W/mK with the mean thermal conductivity of 1.09 W/mK. The mean thermal diffusivity is 5.7×10-7 m2/s with the minimum value of 4.2×10-7 m2/s and the maximum value of 8.0×10-7 m2/s. Volumetric heat capacity varies from 1.5×106 J/m3K to 2.11×106 J/m3K with the mean volumetric heat capacity of 1.91×106 J/m3K. In addition, physical and chemical properties (e.g., bitumen content, electric resistivity, porosity, gamma ray and so on) of oil sand samples have been measured by geophysical logging and in the laboratory. We are now proceeding to investigate the relationship between thermal properties and physical/chemical properties of oil sand.

  19. Evaluation of Durability Parameters of Concrete with Manufacture Sand and River Sand

    Science.gov (United States)

    Sangoju, Bhaskar; Ramesh, G.; Bharatkumar, B. H.; Ramanjaneyulu, K.

    2017-06-01

    Most of the states in our country have banned sand quarrying from the river beds, causing a scarcity of natural river sand for the construction sector. Manufacture sand (M-sand) is one of the alternate solutions to replace the river sand (R-sand) in concrete. The main aim of the present study is to evaluate the durability parameters of concrete with M-sand when compared to that of concrete with R-sand. Corrosion of reinforcement is one of the main deteriorating mechanisms of reinforced concrete due to the ingress of chloride ions or carbon-di-oxide. For comparative evaluation of durability parameters, accelerated tests such as Rapid Chloride Permeability Test, Rapid Chloride Migration Test and accelerated carbonation test were carried out on specimens of R-sand and M-sand. All tests were carried out after 90 days of casting. Test results reveal that the durability parameters of the concrete with M-sand in chloride induced environment is relatively better than that of concrete with R-sand and hence is recommended to use M-sand as a replacement to R-sand.

  20. Sand deposit-detecting method and its application in model test of sand flow

    Institute of Scientific and Technical Information of China (English)

    黎伟; 房营光; 莫海鸿; 谷任国; 陈俊生

    2013-01-01

    Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale model test of sand-flow method. The real-time data of sand-deposit height and radius were obtained by the self-developed sand-deposit detectors. The test results show that the detecting method is simple and has high precision. In the use of sand-flow method, the sand-carrying capability of fluid is limited, and sand particles are all transported to the sand-deposit periphery through crater, gap and chutes after the sand deposit formed. The diffusion range of the particles outside the sand-deposit does not exceed 2.0 m. Severe sorting of sand particles is not observed because of the unique oblique-layered depositing process. The temporal and spatial distributions of gap and chutes directly affect the sand-deposit expansion, and the expansion trend of the average sand-deposit radius accords with quadratic time-history curve.

  1. The properties of X-ray selected and radio-selected BL Lacertae objects%X-选择和射电选择BL Lax天体的性质

    Institute of Scientific and Technical Information of China (English)

    樊军辉; 王洪光; 刘怡; 张江水; 袁聿海; 张永伟; 苏江波

    2007-01-01

    BL Lac天体表现出一系列特殊的观测性质.按照巡天方式可以分为X-选择和射电选择BL Lac天体.很多人讨论了这两者之间的关系.文章的主要工作是:①选取了两个样本;②收集了最高观测偏振读,寄主星系的绝对星等、核主导系数等;③计算了热光度、同步辐射峰频以及峰频所对应的光度、有效谱指数.基于这些数据,考察了两类BL Lac天体的性质.结果表明:X-选择和射电选择BL Lac天体在热光度、核主导系数以及有效谱指教等性质是不同的,但它们具有很相似的同步峰频光度.%BL Lacertae objects show some particularly observational properties. They were classified as radio-selected and X-ray selected BL Lacertae objects from surveys. Many authors have investigated maximum optical polarization, absolute magnitude of the host galaxy, and core-dominance parameter,cy, and the effective spectral indexes for some objects. Based on those data, we revisited the properties of BL Lacertae objects. The results show that radio-selected and X-ray selected BL Lacertae objects are different in the bolometric luminosity, the core-dominance parameters, and the effective spectral indexes, but they have similar peak-frequency luminosity.

  2. Seasonal patterns of body temperature and microhabitat selection in a lacertid lizard

    Science.gov (United States)

    Ortega, Zaida; Pérez-Mellado, Valentín

    2016-11-01

    In temperate areas, seasonal changes entail a source of environmental variation potentially important for organisms. Temperate ectotherms may be adapted to the seasonal fluctuations in environmental traits. For lizards, behavioural adaptations regarding microhabitat selection could arise to improve thermoregulation during the different seasons. However, little is still known about which traits influence microhabitat selection of lizards and their adaptation to seasonality. Here we used Podarcis guadarramae to study the role of potential intrinsic (body size, sex, age) and environmental traits (air and substrate temperatures, wind speed, and sunlight) in the seasonal changes of body temperatures and microhabitat selection of lizards. We measured body temperatures of lizards in the same habitat during the four seasons and compared the climatic variables of the microhabitats selected by lizards with the mean climatic conditions available in their habitat. Body temperatures were similar for adult males, adult females, and juveniles within each season, being significantly higher in summer than in the other seasons, and in spring than in winter. The same pattern was found regarding substrate and air temperatures of the selected microhabitats. Wind speed and air temperature did not affect body temperatures, while body length was marginally significant and substrate temperatures and season did affect the body temperatures of lizards. Our results during the whole year support the idea that the seasonality could be the most important factor affecting body temperatures of these temperate species. Regarding microhabitat selection, environmental constraints, as environmental temperatures and wind speed, affected the seasonal changes on behavioural thermoregulation of lizards. This effect was similar between sexes and age classes, and was independent of body size. In addition, importance of sunlight exposure of the selected microhabitats (full sun, filtered sun, or shade) also

  3. Ultraviolet radiation does not increase oxidative stress in the lizard Psammodromus algirus along an elevational gradient.

    Science.gov (United States)

    Reguera, Senda; Zamora-Camacho, Francisco J; Melero, Elena; García-Mesa, Sergio; Trenzado, Cristina E; Cabrerizo, Marco J; Sanz, Ana; Moreno-Rueda, Gregorio

    2015-05-01

    Lizards, as ectotherms, spend much time basking for thermoregulating exposed to solar radiation. Consequently, they are subjected to ultraviolet radiation (UVR), which is the most harmful component of solar radiation spectrum. UVR can provoke damages, from the molecular to tissue level, even cause death. Photooxidation triggered by UVR produces reactive oxidative species (ROS). When antioxidant machinery cannot combat the ROS concentration, oxidative stress occurs in the organisms. Given that UVR increases with elevation, we hypothesised that lizards from high elevations should be better adapted against UVR than lizards from lower elevations. In this work, we test this hypothesis in Psammodromus algirus along an elevation gradient (three elevational belts, from 300 to 2500 m above sea level). We ran an experiment in which lizards from each elevation belt were exposed to 5-hour doses of UVR (UV-light bulb, experimental group) or photosynthetically active radiation (white-light bulb, control group) and, 24 h after the exposure, we took tissue samples from the tail. We measured oxidative damage (lipid and protein peroxidation) and antioxidant capacity as oxidative-stress biomarkers. We found no differences in oxidative stress between treatments. However, consistent with a previous work, less oxidative damage appeared in lizards from the highlands. We conclude that UVR is not a stressor agent for P. algirus; however, our findings suggest that the lowland environment is more oxidative for lizards. Therefore, P. algirus is well adapted to inhabit a large elevation range, and this would favour the lizard in case it ascends in response to global climate change.

  4. SAND

    DEFF Research Database (Denmark)

    Thorsen, Grete

    Der er udført et konsolideringsforsøg med bakkesand fra Lunds grusgrav, Lund no. O. forsøget er udført i samme konsolideringsapparat, som er anvendt til måling af deformationsegenskaberne af mange forskellige danske jordarter. Forsøgsresultaterne er søgt tolket som ved forsøg med andre jordarter....

  5. Asymmetrical mate preference in recently adapted White Sands and black lava populations of Sceloporus undulatus

    Institute of Scientific and Technical Information of China (English)

    Kayla M.HARDWICK; Jeanne M.ROBERTSON; Erica Bree ROSENBLUM

    2013-01-01

    Speciation can proceed rapidly when natural and sexual selection act in concert.For example speciation can be accelerated when traits that confer a selective advantage in a particular habitat also influence mate preference.Studying parallel but evolutionarily independent instances of ecological divergence can illuminate the interaction between natural and sexual selection during speciation.Locally adapted populations of the eastern fence lizard Sceloporus undulatus have recently evolved in three different habitats in the Chihuahuan desert:blanched color morphs occur on the gypsum dunes of White Sands,melanic color morphs occur on the Carrizozo lava flow,and brown color morphs occur in the surrounding desert scrubland.In addition to differences in cryptic dorsal coloration,populations also differ in the size and color of ventral patches used for social signaling.This system therefore provides an opportunity to investigate the interplay of natural and sexual selection during rapid ecological speciation.We used mate preference experiments to determine whether locally adapted populations may exhibit the early stages of behavioral reproductive isolation.We observed an asymmetrical mate preference in this system; White Sands males preferentially courted local females,while males from dark soils and black lava populations did not exhibit a preference for local mates.We also found that female behavior and ventral patch phenotype were associated with male courtship.Our results suggest that the observed preference for local mates evolved at White Sands,and we discuss the possible link between local adaptation and traits involved in mate preference in this system [Current Zoology 59 (1):20-30,2013].

  6. Asymmetrical mate preference in recently adapted White Sands and black lava populations of Sceloporus undulatus

    Directory of Open Access Journals (Sweden)

    Kayla M. HARDWICK1, Jeanne M. ROBERTSON, Erica Bree ROSENBLUM

    2013-01-01

    Full Text Available Speciation can proceed rapidly when natural and sexual selection act in concert. For example speciation can be accelerated when traits that confer a selective advantage in a particular habitat also influence mate preference. Studying parallel but evolutionarily independent instances of ecological divergence can illuminate the interaction between natural and sexual selection during speciation. Locally adapted populations of the eastern fence lizard Sceloporus undulatus have recently evolved in three different habitats in the Chihuahuan desert: blanched color morphs occur on the gypsum dunes of White Sands, melanic color morphs occur on the Carrizozo lava flow, and brown color morphs occur in the surrounding desert scrubland. In addition to differences in cryptic dorsal coloration, populations also differ in the size and color of ventral patches used for social signaling. This system therefore provides an opportunity to investigate the interplay of natural and sexual selection during rapid ecological speciation. We used mate preference experiments to determine whether locally adapted populations may exhibit the early stages of behavioral reproductive isolation. We observed an asymmetrical mate preference in this system; White Sands males preferentially courted local females, while males from dark soils and black lava populations did not exhibit a preference for local mates. We also found that female behavior and ventral patch phenotype were associated with male courtship. Our results suggest that the observed preference for local mates evolved at White Sands, and we discuss the possible link between local adaptation and traits involved in mate preference in this system [Current Zoology 59 (1: 20–30, 2013].

  7. Liquefaction of Sand under Low Confining Pressure

    Institute of Scientific and Technical Information of China (English)

    YANG Shaoli; Rolf Sandven; Lars Grande

    2003-01-01

    Undrained behaviour of sand under low cell pressure was studied in static and cyclic triaxial tests. It was found that very loose sand liquefies under static loading with the relative density being a key parameter for the undrained behaviour of sand. In cyclic triaxial tests, pore water pressures built up during the cyclic loading and exceeded the confining cell pressure. This process was accompanied by a large sudden increase in axial deformation. The necessary number of cycles to obtain liquefaction was related to the confining cell pressure, the amplitude of cyclic loading and the relative density of sand.In addition, the patterns of pore water pressure response are different from those of sand samples with different relative densities. The test results are very useful for expounding scour mechanism around coastal structures since they relate to the low stress behaviour of the sand.

  8. Creep Behavior of Frozen Sand.

    Science.gov (United States)

    1981-06-01

    temperature and stress range. There was a 2strong stress dependance to S (r =0.95) for saturated Manchester Fine Sand which does not agree with RPT. The...Curves at High Stress 161 Ratio D/Du = 0.505 for Frozen HF’S at w=10% IV-20 Minimum Strain Rate Dependance on Stress 162 Ratio for Frozen MFS IV-21 Minimum...Strain Rate Dependance on Relative 163 Density for Frozen MFS IV-22 Temperature Stage Test on Frozen Saturated 164 MFS under a Load of D=9.24MPa Fig

  9. Variation in skull size and shape of the Common wall lizard (Podarcis muralis): allometric and non-allometric shape changes

    NARCIS (Netherlands)

    Urošević, A.; Ljubisavljević, K.; Ivanović, A.

    2014-01-01

    We analysed patterns of skull size and shape variation among populations of the Common wall lizard (Podarcis muralis) in the Central Balkans, particularly the effecs of insularity and the presence of the ecologically similar lacertid lizard species P. melisellensis. Two components of shape variation

  10. Variation in skull size and shape of the Common wall lizard (Podarcis muralis): allometric and non-allometric shape changes

    NARCIS (Netherlands)

    Urošević, A.; Ljubisavljević, K.; Ivanović, A.

    2014-01-01

    We analysed patterns of skull size and shape variation among populations of the Common wall lizard (Podarcis muralis) in the Central Balkans, particularly the effecs of insularity and the presence of the ecologically similar lacertid lizard species P. melisellensis. Two components of shape variation

  11. Are mountain habitats becoming more suitable for generalist than cold-adapted lizards thermoregulation?

    Science.gov (United States)

    Ortega, Zaida; Mencía, Abraham; Pérez-Mellado, Valentín

    2016-01-01

    Mountain lizards are highly vulnerable to climate change, and the continuous warming of their habitats could be seriously threatening their survival. We aim to compare the thermal ecology and microhabitat selection of a mountain lizard, Iberolacerta galani, and a widely distributed lizard, Podarcis bocagei, in a montane area. Both species are currently in close syntopy in the study area, at 1,400 m above the sea level. We determined the precision, accuracy and effectiveness of thermoregulation, and the thermal quality of habitat for both species. We also compared the selection of thermal microhabitats between both species. Results show that I. galani is a cold-adapted thermal specialist with a preferred temperature range of 27.9-29.7 °C, while P. bocagei would be a thermal generalist, with a broader and higher preferred temperature range (30.1-34.5 °C). In addition, I. galani selects rocky substrates while P. bocagei selects warmer soil and leaf litter substrates. The thermal quality of the habitat is higher for P. bocagei than for I. galani. Finally, P. bocagei achieves a significantly higher effectiveness of thermoregulation (0.87) than I. galani (0.80). Therefore, these mountain habitat conditions seem currently more suitable for performance of thermophilic generalist lizards than for cold-specialist lizards.

  12. Are mountain habitats becoming more suitable for generalist than cold-adapted lizards thermoregulation?

    Directory of Open Access Journals (Sweden)

    Zaida Ortega

    2016-05-01

    Full Text Available Mountain lizards are highly vulnerable to climate change, and the continuous warming of their habitats could be seriously threatening their survival. We aim to compare the thermal ecology and microhabitat selection of a mountain lizard, Iberolacerta galani, and a widely distributed lizard, Podarcis bocagei, in a montane area. Both species are currently in close syntopy in the study area, at 1,400 m above the sea level. We determined the precision, accuracy and effectiveness of thermoregulation, and the thermal quality of habitat for both species. We also compared the selection of thermal microhabitats between both species. Results show that I. galani is a cold-adapted thermal specialist with a preferred temperature range of 27.9–29.7 °C, while P. bocagei would be a thermal generalist, with a broader and higher preferred temperature range (30.1–34.5 °C. In addition, I. galani selects rocky substrates while P. bocagei selects warmer soil and leaf litter substrates. The thermal quality of the habitat is higher for P. bocagei than for I. galani. Finally, P. bocagei achieves a significantly higher effectiveness of thermoregulation (0.87 than I. galani (0.80. Therefore, these mountain habitat conditions seem currently more suitable for performance of thermophilic generalist lizards than for cold-specialist lizards.

  13. Photographic capture-recapture sampling for assessing populations of the Indian gliding lizard Draco dussumieri.

    Science.gov (United States)

    Sreekar, Rachakonda; Purushotham, Chetana B; Saini, Katya; Rao, Shyam N; Pelletier, Simon; Chaplod, Saniya

    2013-01-01

    The usage of invasive tagging methods to assess lizard populations has often been criticised, due to the potential negative effects of marking, which possibly cause increased mortality or altered behaviour. The development of safe, less invasive techniques is essential for improved ecological study and conservation of lizard populations. In this study, we describe a photographic capture-recapture (CR) technique for estimating Draco dussumieri (Agamidae) populations. We used photographs of the ventral surface of the patagium to identify individuals. To establish that the naturally occurring blotches remained constant through time, we compared capture and recapture photographs of 45 pen-marked individuals after a 30 day interval. No changes in blotches were observed and individual lizards could be identified with 100% accuracy. The population density of D. dussumieri in a two hectare areca-nut plantation was estimated using the CR technique with ten sampling occasions over a ten day period. The resulting recapture histories for 24 individuals were analysed using population models in the program CAPTURE. All models indicated that nearly all individuals were captured. The estimated probability for capturing D. dussumieri on at least one occasion was 0.92 and the estimated population density was 13±1.65 lizards/ha. Our results demonstrate the potential for applying CR to population studies in gliding lizards (Draco spp.) and other species with distinctive markings.

  14. Learning outdoors: male lizards show flexible spatial learning under semi-natural conditions.

    Science.gov (United States)

    Noble, Daniel W A; Carazo, Pau; Whiting, Martin J

    2012-12-23

    Spatial cognition is predicted to be a fundamental component of fitness in many lizard species, and yet some studies suggest that it is relatively slow and inflexible. However, such claims are based on work conducted using experimental designs or in artificial contexts that may underestimate their cognitive abilities. We used a biologically realistic experimental procedure (using simulated predatory attacks) to study spatial learning and its flexibility in the lizard Eulamprus quoyii in semi-natural outdoor enclosures under similar conditions to those experienced by lizards in the wild. To evaluate the flexibility of spatial learning, we conducted a reversal spatial-learning task in which positive and negative reinforcements of learnt spatial stimuli were switched. Nineteen (32%) male lizards learnt both tasks within 10 days (spatial task mean: 8.16 ± 0.69 (s.e.) and reversal spatial task mean: 10.74 ± 0.98 (s.e.) trials). We demonstrate that E. quoyii are capable of flexible spatial learning and suggest that future studies focus on a range of lizard species which differ in phylogeny and/or ecology, using biologically relevant cognitive tasks, in an effort to bridge the cognitive divide between ecto- and endotherms.

  15. Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms

    Science.gov (United States)

    Koludarov, Ivan; Jackson, Timothy NW; op den Brouw, Bianca; Dobson, James; Dashevsky, Daniel; Clemente, Christofer J.; Stockdale, Edward J.; Cochran, Chip; Debono, Jordan; Stephens, Carson; Panagides, Nadya; Li, Bin; Roy Manchadi, Mary-Louise; Violette, Aude; Fourmy, Rudy; Hendrikx, Iwan; Nouwens, Amanda; Clements, Judith; Martelli, Paolo; Kwok, Hang Fai; Fry, Bryan G.

    2017-01-01

    While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds. PMID:28783084

  16. Enter the Dragon: The Dynamic and Multifunctional Evolution of Anguimorpha Lizard Venoms

    Directory of Open Access Journals (Sweden)

    Ivan Koludarov

    2017-08-01

    Full Text Available While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds.

  17. Photographic capture-recapture sampling for assessing populations of the Indian gliding lizard Draco dussumieri.

    Directory of Open Access Journals (Sweden)

    Rachakonda Sreekar

    Full Text Available The usage of invasive tagging methods to assess lizard populations has often been criticised, due to the potential negative effects of marking, which possibly cause increased mortality or altered behaviour. The development of safe, less invasive techniques is essential for improved ecological study and conservation of lizard populations. In this study, we describe a photographic capture-recapture (CR technique for estimating Draco dussumieri (Agamidae populations. We used photographs of the ventral surface of the patagium to identify individuals. To establish that the naturally occurring blotches remained constant through time, we compared capture and recapture photographs of 45 pen-marked individuals after a 30 day interval. No changes in blotches were observed and individual lizards could be identified with 100% accuracy. The population density of D. dussumieri in a two hectare areca-nut plantation was estimated using the CR technique with ten sampling occasions over a ten day period. The resulting recapture histories for 24 individuals were analysed using population models in the program CAPTURE. All models indicated that nearly all individuals were captured. The estimated probability for capturing D. dussumieri on at least one occasion was 0.92 and the estimated population density was 13±1.65 lizards/ha. Our results demonstrate the potential for applying CR to population studies in gliding lizards (Draco spp. and other species with distinctive markings.

  18. Local enhancement and social foraging in a non-social insular lizard.

    Science.gov (United States)

    Pérez-Cembranos, Ana; Pérez-Mellado, Valentín

    2015-05-01

    Even in solitary foragers, conspecifics can provide reliable information about food location. The insular lizard Podarcis lilfordi is a solitary species with high population densities that sometimes aggregate around rich food patches. Its diet includes novel and unpredictable resources, such as carcasses or plants, whose exploitation quickly became widespread among the population. We tested the use of social information by lizards through some field experiments in which they had to choose one of the two pieces of fruit. Probably due to local enhancement, lizards preferred to feed on the piece of fruit where conspecifics or lizard-shaped models were already present. Conspecifics' behaviour, but also their mere presence, seems to be a valuable source of information to decide where to feed. Lizards also showed a strong attraction to conspecifics, even in the absence of food. Maybe the presence of a group is interpreted as an indirect cue for the presence of food. The group size was not important to females, but males had a significantly higher attraction towards groups with three conspecifics. We discuss some characteristics of P. lilfordi at Aire Island that can explain the development of the observed social foraging, as well as their possible consequences.

  19. Short-term dispersal response of an endangered Australian lizard varies with time of year.

    Science.gov (United States)

    Ebrahimi, Mehregan; Bull, C Michael

    2014-01-01

    Dispersal is an important component in the demography of animal populations. Many animals show seasonal changes in their tendency to disperse, reflecting changes in resource availability, mating opportunities, or in population age structure at the time when new offspring enter the population. Understanding when and why dispersal occurs can be important for the management of endangered species. The pygmy bluetongue lizard is an endangered Australian species that occupies and defends single burrow refuges for extended periods of time, rarely moving far from the burrow entrance. However, previous pitfall trapping data have suggested movement of adult males in spring and of juveniles in autumn of each year. In the current study we compared behaviours of adult lizards each month, over the spring-summer activity period over two consecutive field seasons, to provide deeper understanding of the seasonal dispersal pattern. We released adult pygmy bluetongue lizards into a central area, provided with artificial burrows, within large enclosures, and monitored the behaviour and movements of the released lizards over a four day period. There was a consistent decline in time spent basking, amount of movement around burrow entrances, and rates of dispersal from the central release area from early spring to late summer. Results could be relevant to understanding and managing natural populations and for any translocation attempts of this endangered lizard species.

  20. Turn up the heat: thermal tolerances of lizards at La Selva, Costa Rica.

    Science.gov (United States)

    Brusch, George A; Taylor, Emily N; Whitfield, Steven M

    2016-02-01

    Global temperature increases over the next century are predicted to contribute to the extinction of a number of taxa, including up to 40% of all lizard species. Lizards adapted to living in lowland tropical areas are especially vulnerable because of their dependence on specific microhabitats, low vagility, and a reduced capacity to physiologically adjust to environmental change. To assess the potential effects of climate change on lizards in the lowland tropics, we measured the critical thermal maximum (CTmax) of ten species from La Selva, Costa Rica. We also examined how well body size, microhabitat type, and species predicted the CTmax. We used current temperature data along with projected temperature increases for 2080 to predict which species may be at the greatest risk at La Selva. Of the ten species sampled, four are at serious risk of lowland extirpation and three others might also be at risk under the highest predicted temperature-increase models. Forest floor lizards at La Selva have already experienced significant population declines over the past 40 years, and we found that each of the forest floor species we studied is at serious risk of local extirpation. We also found that microhabitat type is the strongest predictor of CTmax, demonstrating the profound impact habitat specialization has on the thermal limits of tropical lizards.

  1. Reproduction and morphology of the common lizard (Zootoca vivipara) from montane populations in Slovakia.

    Science.gov (United States)

    Horváthová, Terézia; Baláž, Michal; Jandzik, David

    2013-02-01

    The common lizard, Zootoca vivipara (Lichtenstein, 1823), shows high variation in life histories and morphology across its range, which comprises almost the entire Palearctic region. However, this variation is not congruent with the species phylogeny. This suggests an important role of the environment in shaping the variation in morphology and life histories of this species. As most data on life histories originate from only a small number of populations and do not cover the species' geographic range and phylogenetic diversity, to fill a gap and provide more information for future comparative studies we investigated reproduction and morphology in two montane populations from Slovakia, central Europe. This region is characterized by taxonomic and phylogenetic diversity and both montane and lowland ecological forms of the common lizard occur here. The common lizards from the Slovak populations are sexually dimorphic, with females having larger body and abdomen lengths and males having larger heads and longer legs. Female common lizards start to reproduce at a relatively large size compared to most other populations. This is consistent with a relatively short activity season, which has been shown to be the main factor driving variation in body size in the common lizard. Clutch size was also relatively high and positively correlated with body size, abdomen size and head size. One third of all females attaining the size of the smallest gravid female showed no signs of reproductive activity despite mating opportunities, suggesting that not all females reproduce annually in this population.

  2. High antipredatory efficiency of insular lizards: a warning signal of excessive specimen collection?

    Directory of Open Access Journals (Sweden)

    Miguel Delibes

    Full Text Available We live-captured lizards on islands in the Gulf of California and the Baja California peninsula mainland, and compared their ability to escape predation. Contrary to expectations, endemic lizard species from uninhabited islands fled from humans earlier and more efficiently than those from peninsular mainland areas. In fact, 58.2% (n=146 of the lizards we tried to capture on the various islands escaped successfully, while this percentage was only 14.4% (n=160 on the peninsular mainland. Separate evidence (e.g., proportion of regenerated tails, low human population at the collection areas, etc. challenges several potential explanations for the higher antipredatory efficiency of insular lizards (e.g., more predation pressure on islands, habituation to humans on the peninsula, etc.. Instead, we suggest that the ability of insular lizards to avoid predators may be related to harvesting by humans, perhaps due to the value of endemic species as rare taxonomic entities. If this hypothesis is correct, predation-related behavioral changes in rare species could provide early warning signals of their over-exploitation, thus encouraging the adoption of conservation measures.

  3. Population genetic structure, gene flow and sex-biased dispersal in frillneck lizards (Chlamydosaurus kingii).

    Science.gov (United States)

    Ujvari, Beata; Dowton, Mark; Madsen, Thomas

    2008-08-01

    By using both mitochondrial and nuclear multiloci markers, we explored population genetic structure, gene flow and sex-specific dispersal of frillneck lizards (Chlamydosaurus kingii) sampled at three locations, separated by 10 to 50 km, in a homogenous savannah woodland in tropical Australia. Apart from a recombinant lizard, the mitochondrial analyses revealed two nonoverlapping haplotypes/populations, while the nuclear markers showed that the frillneck lizards represented three separate clusters/populations. Due to the small population size of the mtDNA, fixation may occur via founder effects and/or drift. We therefore suggest that either of these two processes, or a combination of the two, are the most likely causes of the discordant results obtained from the mitochondrial and the nuclear markers. In contrast to the nonoverlapping mitochondrial haplotypes, in 12 out of 74 lizards, mixed nuclear genotypes were observed, hence revealing a limited nuclear gene flow. Although gene flow should ultimately result in a blending of the populations, we propose that the distinct nuclear population structure is maintained by frequent fires resulting in local bottlenecks, and concomitant spatial separation of the frillneck lizard populations. Limited mark-recapture data and the difference in distribution of the mitochondrial and nuclear markers suggest that the mixed nuclear genotypes were caused by juvenile male-biased dispersal.

  4. Recent advances in waterglass sand technologies

    Institute of Scientific and Technical Information of China (English)

    ZHU Chun-xi

    2007-01-01

    This paper reports some new understandings and advances in waterglass sand technologies. The multiple chemical modification process can increase the binding strength of the waterglass sand by up to 50%-70%.Therefore, the additions of the modified waterglass can be decreased to 3.0%-4.0% for CO2 process and to 2.0%-2.5% for organic ester hardening process, and greatly improve the collapsibility and reclaimability of the sand. Based on the new understandings and experimental results reported in this paper, several original ideas, such as nano modification, have been proposed to promote advances of waterglass sand technologies,

  5. PROSPECTS FIXATION DRIFT SANDS PHYSICOCHEMICAL METHOD

    Directory of Open Access Journals (Sweden)

    Maujuda MUZAFFAROVA

    2016-09-01

    Full Text Available This article is based on the theoretical foundations of secure mobile sand being considered for reducing the negative impact of one of the manifestations of exogenous plains on such an important natural-technical system as a railroad. It suggests practical measures to build a system of design protection against sand drifts. The article also suggests ways to conserve resources and rational use of machinery and performers as well as the consolidation of mobile sand wet with water soluble waste of local production of waste dextrin. Consolidation is exposed on dry and wet sand.

  6. Innovative developments in sand reclamation technologies

    Directory of Open Access Journals (Sweden)

    R. Dañko

    2011-04-01

    Full Text Available Proper sand management and efficient sand reclamation system are two main factors influencing economical and ecological side of modern foundry plant. It is well known fact that the production of 1 metric ton of casting from ferrous alloys generates circa 1 metric ton of waste [1], which due to containing certain amounts of harmful and dangerous compounds should undergo a reclamation – at least of the main component, which means a silica sand grains. The paper present problems of scientific and development research concerning the innovative reclamation technologies of used foundry sands such as: mechanical-cryogenic reclamation and innovative thermal reclamation.

  7. Can changes in the distribution of lizard species over the past 50 years be attributed to climate change?

    Science.gov (United States)

    Wu, Jianguo

    2016-08-01

    We analyzed changes in the distributions of nine lizard species in China over the past 50 years and identified whether these changes could be attributed to climate change. Long-term records of lizard distributions, grey relational analysis, fuzzy set classification techniques, and attribution methods were used. The distribution of nearly half of the lizard species primarily shifted northward, westward, or eastward since the 1970s, and most changes were related to the thermal index. In response to climate change over the past 50 years, the distribution boundary and center of some species have mainly shifted northward, westward, or eastward, with some irregular shifting during the process. The observed and predicted changes in distribution were highly consistent for some lizard species. The changes in the northern and eastern distribution limits of nearly half of the lizard species and the western limits and distribution centers of several species can be attributed to climate change.

  8. Sand Failure Mechanism and Sanding Parameters in Niger Delta Oil Reservoirs

    OpenAIRE

    Sunday Isehunwa,; Andrew Farotade

    2010-01-01

    Sand production is a major issue during oil and gas production from unconsolidated reservoirs. In predicting the onset of sand production, it is important to accurately determine the failure mechanism and the contributing parameters. The aim of this study was to determine sand failure mechanism in the Niger-Delta, identify themajor contributing parameters and evaluate their effects on sanding.Completion and production data from 78 strings completed on 22 reservoirs in a Niger Delta oil Field ...

  9. Seasonal geomorphic processes and rates of sand movement at Mount Baldy dune in Indiana, USA

    Science.gov (United States)

    Kilibarda, Zoran; Kilibarda, Vesna

    2016-12-01

    Winds are very strong, frequent, and have high energy (annual DP ∼800 VU) along the southern shores of Lake Michigan, allowing the coexistence of fixed and active dunes. Six years (2007-13) of monitoring Mount Baldy in the Indiana Dunes National Lakeshore reveals that this is the most active coastal dune in the Great Lakes region. This paper documents aeolian processes and changes in the dune's morphology that occur temporarily, following storms, or seasonally, due to weather (climate) variations. Most of the sand transport in this area takes place during strong storms with gale force (>17.5 m/s) winds, which occur in the autumn and winter months. A single storm, such as the October 28-31, 2013 event, can contribute 25% of the annual sand transport and dune movement inland. In its most active year (June 1, 2011 through May 31, 2012), Mount Baldy moved inland on average 4.34 m, with a maximum of 6.52 m along the blowout's axis (155° azimuth). During this particularly active season, there were six storms with sustained gale force winds, winter air temperatures were warmer than average, and shelf ice on Lake Michigan lasted only one day. The dune is least active during the summer season, when the winds are weakest. The late fall and winter winds are the strongest. But in a typical year, most of the dune's advance inland takes place during the spring thaw when sand is released from over-steepened and lumpy slip face, allowing it to avalanche to the toe of the slip face. However, with a warming air temperatures, a reduction in the duration of winter shelf ice, and rising Lake Michigan levels, the annual rates of sand transport and dune movement may increase. The recent Mount Baldy management strategy, which includes planting vegetation and installing wind barriers on the dune's stoss side in an effort to fix the dune and stop its further movement inland, may potentially cause the destruction of the mobile sand, open dune habitat, resulting in the extinction of rare

  10. Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary

    Science.gov (United States)

    Longrich, Nicholas R.; Bhullar, Bhart-Anjan S.; Gauthier, Jacques A.

    2012-01-01

    The Cretaceous–Paleogene (K-Pg) boundary is marked by a major mass extinction, yet this event is thought to have had little effect on the diversity of lizards and snakes (Squamata). A revision of fossil squamates from the Maastrichtian and Paleocene of North America shows that lizards and snakes suffered a devastating mass extinction coinciding with the Chicxulub asteroid impact. Species-level extinction was 83%, and the K-Pg event resulted in the elimination of many lizard groups and a dramatic decrease in morphological disparity. Survival was associated with small body size and perhaps large geographic range. The recovery was prolonged; diversity did not approach Cretaceous levels until 10 My after the extinction, and resulted in a dramatic change in faunal composition. The squamate fossil record shows that the end-Cretaceous mass extinction was far more severe than previously believed, and underscores the role played by mass extinctions in driving diversification. PMID:23236177

  11. Mass extinction of lizards and snakes at the Cretaceous-Paleogene boundary.

    Science.gov (United States)

    Longrich, Nicholas R; Bhullar, Bhart-Anjan S; Gauthier, Jacques A

    2012-12-26

    The Cretaceous-Paleogene (K-Pg) boundary is marked by a major mass extinction, yet this event is thought to have had little effect on the diversity of lizards and snakes (Squamata). A revision of fossil squamates from the Maastrichtian and Paleocene of North America shows that lizards and snakes suffered a devastating mass extinction coinciding with the Chicxulub asteroid impact. Species-level extinction was 83%, and the K-Pg event resulted in the elimination of many lizard groups and a dramatic decrease in morphological disparity. Survival was associated with small body size and perhaps large geographic range. The recovery was prolonged; diversity did not approach Cretaceous levels until 10 My after the extinction, and resulted in a dramatic change in faunal composition. The squamate fossil record shows that the end-Cretaceous mass extinction was far more severe than previously believed, and underscores the role played by mass extinctions in driving diversification.

  12. Population and conservation strategies for the Chinese crocodile lizard (Shinisaurus crocodilurus in China

    Directory of Open Access Journals (Sweden)

    Huang, C. M.

    2008-12-01

    Full Text Available The Chinese crocodile lizard (Shinisaurus crocodilurus is an unusual anguimorph lizard found mainly in China. Transect surveys estimate a total wild population of about 950 individuals in China. This is a dramatic decrease compared with previous surveys. At present, there are only eight areas of distribution. No Chinese crocodile lizards have been found in four former areas for several years. Investigations have demonstrated that poaching has contributed directly to the population decline. Habitat destruction, and in particular water flow, is the second most important factor. Mining, small scale dam construction, electro-fishing and poisoning of fish in the stream also contribute to population decline. Therefore, educating local people, punishing illegal poaching, and strengthening scientific research are urgent.

  13. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards.

    Science.gov (United States)

    Daza, Juan D; Stanley, Edward L; Wagner, Philipp; Bauer, Aaron M; Grimaldi, David A

    2016-03-01

    Modern tropical forests harbor an enormous diversity of squamates, but fossilization in such environments is uncommon and little is known about tropical lizard assemblages of the Mesozoic. We report the oldest lizard assemblage preserved in amber, providing insight into the poorly preserved but potentially diverse mid-Cretaceous paleotropics. Twelve specimens from the Albian-Cenomanian boundary of Myanmar (99 Ma) preserve fine details of soft tissue and osteology, and high-resolution x-ray computed tomography permits detailed comparisons to extant and extinct lizards. The extraordinary preservation allows several specimens to be confidently assigned to groups including stem Gekkota and stem Chamaleonidae. Other taxa are assignable to crown clades on the basis of similar traits. The detailed preservation of osteological and soft tissue characters in these specimens may facilitate their precise phylogenetic placement, making them useful calibration points for molecular divergence time estimates and potential keys for resolving conflicts in higher-order squamate relationships.

  14. Nutritional perfomance of Tupinambis merianae lizards fed with corn starch as source of energy

    Directory of Open Access Journals (Sweden)

    Harold Vega Parry

    2009-07-01

    Full Text Available Efficiency in processing complex carbohydrates as a source of energy was studied in Tupinambis merianae lizards. Four isoproteic and isoenergetic diets in which different percentages of corn starch substituted fat (0, 10, 20 and 30 dry matter in the diet were provided. Even though consumption was similar in all diets, growth and feeding conversion rates decreased significantly with corn starch supplies of 10% and more. At the end of the trial, pancreatic alpha-amylase activity showed correlated increases, yet these were insufficient to compensate corn starch supplies. Results suggest that Tupinambis merianae lizards have a restricted omnivorous capacity. Therefore, diet formulation for these lizards should exclude high molecular weight carbohydrates.

  15. A new Early Cretaceous lizard with well-preserved scale impressions from western Liaoning, China

    Institute of Scientific and Technical Information of China (English)

    JI Shu'an

    2005-01-01

    A new small lizard, Liaoningolacerta brevirostra gen. et sp. nov., from the Early Cretaceous Yixian Formation of western Liaoning is described in detail. The new specimen was preserved not only by the skeleton, but also by the exceptionally clear scale impressions. This lizard can be included within the taxon Scleroglossa based on its 26 or more presacrals, cruciform interclavicle with a large anterior process, moderately elongated pubis, and slightly notched distal end of tibia. The scales vary evidently in size and shape at different parts of body: small and rhomboid ventral scales, tiny and round limb scales, and large and longitudinally rectangular caudal scales that constitute the caudal whorls. This new finding provides us with more information on the lepidosis of the Mesozoic lizards.

  16. Effects of dexamethasone and gonadotropins on the testis of the adrenalectomized lizard Mabuya carinata (Schn.)

    Science.gov (United States)

    Yajurvedi, H N; Chandramohan, K

    1994-02-01

    The effects of gonadotropins (LH + FSH) and dexamethasone on the spermatogenic and steroidogenic activity in the adrenalectomized Mabuya carinata have been studied. Secondary spermatocytes, spermatids, and spermatozoa were absent, and there was a significant decrease in the activity levels of delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSDH) and glucose-6-phosphate dehydrogenase in the adrenalectomized lizards compared with those of controls. Administration of either dexamethasone or LH + FSH to adrenalectomized lizards resulted in restoration of testicular activity as revealed by the appearance of secondary spermatocytes, spermatids, and spermatozoa and a significant increase in the activity level of delta 5-3 beta-HSDH compared to that of adrenalectomized lizards. The results indicate that impairment in gonadotropin secretion might be a major factor in inducing testicular regression following adrenalectomy in M. carinata.

  17. Stable isotope ecology of a hyper-diverse community of scincid lizards from arid Australia.

    Science.gov (United States)

    Grundler, Maggie R; Pianka, Eric R; Pelegrin, Nicolás; Cowan, Mark A; Rabosky, Daniel L

    2017-01-01

    We assessed the utility of stable isotope analysis as a tool for understanding community ecological structure in a species-rich clade of scincid lizards from one of the world's most diverse lizard communities. Using a phylogenetic comparative framework, we tested whether δ15N and δ13C isotopic composition from individual lizards was correlated with species-specific estimates of diet and habitat use. We find that species are highly divergent in isotopic composition with significant correlations to habitat use, but this relationship shows no phylogenetic signal. Isotopic composition corresponds to empirical observations of diet for some species but much variation remains unexplained. We demonstrate the importance of using a multianalytical approach to questions of long-term dietary preference, and suggest that the use of stable isotopes in combination with stomach content analysis and empirical data on habitat use can potentially reveal patterns in ecological traits at finer scales with important implications for community structuring.

  18. Chronic electrical stimulation drives mitochondrial biogenesis in skeletal muscle of a lizard, Varanus exanthematicus.

    Science.gov (United States)

    Schaeffer, Paul J; Nichols, Scott D; Lindstedt, Stan L

    2007-10-01

    We investigated the capacity for phenotypic plasticity of skeletal muscle from Varanus exanthematicus, the savannah monitor lizard. Iliofibularis muscle from one leg of each lizard was electrically stimulated for 8 weeks. Both stimulated and contralateral control muscles were collected and processed for electron microscopy. We used stereological analysis of muscle cross-sections to quantify the volume densities of contractile elements, sarcoplasmic reticulum, mitochondria and intracellular lipids. We found that mitochondrial volume density was approximately fourfold higher in the stimulated muscle compared to controls, which were similar to previously reported values. Sarcoplasmic reticulum volume density was reduced by an amount similar to the increase in mitochondrial volume density while the volume density of contractile elements remained unchanged. Intracellular lipid accumulation was visibly apparent in many stimulated muscle sections but the volume density of lipids did not reach a significant difference. Although monitor lizards lack the highly developed aerobic metabolism of mammals, they appear to possess the capacity for muscle plasticity.

  19. Levels of helminth infection in the flat lizard Tropidurus semitaeniatus from north-eastern Brazil.

    Science.gov (United States)

    Bezerra, C H; Ávila, R W; Passos, D C; Zanchi-Silva, D; Galdino, C A B

    2016-11-01

    Parasites represent a great, unknown component of animal biodiversity. Recent efforts have begun to uncover patterns of infection by helminth parasites in several Neotropical lizards. The present study reports, for the first time, levels of helminth infection in a population of the flat lizard Tropidurus semitaeniatus. One hundred and thirty-nine lizards were examined and evidence of five intestinal helminth species was found, comprising four species of nematodes, one species of cestode and an unidentified encysted larval nematode. The most frequently occurring species was the intestinal nematode Parapharyngodon alvarengai, which did not exhibit differences in prevalence and intensity of infection relative to host sex or age/body size. Furthermore, helminth species richness was not related to host body size.

  20. Mass extinction of lizards and snakes at the Cretaceous-Paleogene boundary

    Science.gov (United States)

    Longrich, Nicholas R.; Bhullar, Bhart-Anjan S.; Gauthier, Jacques A.

    2012-12-01

    The Cretaceous-Paleogene (K-Pg) boundary is marked by a major mass extinction, yet this event is thought to have had little effect on the diversity of lizards and snakes (Squamata). A revision of fossil squamates from the Maastrichtian and Paleocene of North America shows that lizards and snakes suffered a devastating mass extinction coinciding with the Chicxulub asteroid impact. Species-level extinction was 83%, and the K-Pg event resulted in the elimination of many lizard groups and a dramatic decrease in morphological disparity. Survival was associated with small body size and perhaps large geographic range. The recovery was prolonged; diversity did not approach Cretaceous levels until 10 My after the extinction, and resulted in a dramatic change in faunal composition. The squamate fossil record shows that the end-Cretaceous mass extinction was far more severe than previously believed, and underscores the role played by mass extinctions in driving diversification.

  1. Patterns of sexual dimorphism in Mexican alligator lizards, Barisia imbricata

    Science.gov (United States)

    Dashevsky, Daniel; Meik, Jesse M; Mociño-Deloya, Estrella; Setser, Kirk; Schaack, Sarah

    2013-01-01

    We compare morphological characteristics of male and female Barisia imbricata, Mexican alligator lizards, and find that mass, head length, coloration, incidence of scars from conspecifics, tail loss, and frequency of bearing the color/pattern of the opposite sex are all sexually dimorphic traits. Overall size (measured as snout–vent length), on the other hand, is not different between the two sexes. We use data on bite scar frequency and fecundity to evaluate competing hypotheses regarding the selective forces driving these patterns. We contend that sexual selection, acting through male-male competition, may favor larger mass and head size in males, whereas large females are likely favored by natural selection for greater fecundity. In addition, the frequency of opposite-sex patterning in males versus females may indicate that the costs of agonistic interactions among males are severe enough to allow for an alternative mating strategy. Finally, we discuss how sexual and natural selective forces may interact to drive or mask the evolution of sexually dimorphic traits. PMID:23467394

  2. Sleep and wakefulness in the green iguanid lizard (Iguana iguana).

    Science.gov (United States)

    Ayala-Guerrero, F; Mexicano, G

    2008-11-01

    The reptile Iguana iguana exhibits four states of vigilance: active wakefulness (AW), quiet wakefulness (QW), quiet sleep (QS) and active sleep (AS). Cerebral activity decreases in amplitude and frequency when passing from wakefulness to QS. Both parameters show a slight increase during AS. Heart rate is at a maximum during AW (43.8+/-7.9 beats/min), decreases to a minimum in QS (25.3+/-3.2 beats/min) and increases in AS (36.1+/-5.7 beats/min). Tonical and phasical muscular activity is present in wakefulness, decreases or disappears in QS and reappears in AS. Single or conjugate ocular movements are observed during wakefulness, then disappear in QS and abruptly reappear in AS. Although these reptiles are polyphasic, their sleep shows a tendency to concentrate between 20:00 and 8:00 h. Quiet sleep occupies the greater percentage of the total sleep time. Active sleep episodes are of very short duration, showing an average of 21.5+/-4.9 (mean+/-SD). Compensatory increment of sleep following its total deprivation was significant only for QS. Reaction to stimuli decreased significantly when passing from wakefulness to sleep. It is suggested that the lizard I. iguana displays two sleep phases behaviorally and somatovegetatively similar to slow wave sleep and paradoxical sleep in birds and mammals.

  3. Incubation temperature modifies neonatal thermoregulation in the lizard Anolis carolinensis.

    Science.gov (United States)

    Goodman, Rachel M; Walguarnery, Justin W

    2007-08-01

    The thermal environment experienced during embryonic development can profoundly affect the phenotype, and potentially the fitness, of ectothermic animals. We examined the effect of incubation temperature on the thermal preferences of juveniles in the oviparous lizard, Anolis carolinensis. Temperature preference trials were conducted in a laboratory thermal gradient within 48 hr of hatching and after 22-27 days of maintenance in a common laboratory environment. Incubation temperature had a significant effect on the upper limit of the interquartile range (IQR) of temperatures selected by A. carolinensis within the first 2 days after hatching. Between the first and second trials, the IQR of selected temperatures decreased significantly and both the lower limit of the IQR and the median selected temperature increased significantly. This, along with a significant incubation temperature by time interaction in the upper limit of the IQR, resulted in a pattern of convergence in thermoregulation among treatment groups. The initial differences in selected temperatures, as well as the shift in selected temperatures between first and second trials, demonstrate plasticity in temperature selection. As a previous study failed to find environmentally induced plasticity in temperature selection in adult A. carolinensis, this study suggests that this type of plasticity is exclusive to the period of neonatal development.

  4. Female ornamentation influences male courtship investment in a lizard

    Directory of Open Access Journals (Sweden)

    Devi Meian Stuart-Fox

    2014-02-01

    Full Text Available Female signals of reproductive status often comprise both distinctive colour patches and behaviours but their relative influence on male courtship investment is unclear. We examined the role of female-specific colouration in signalling reproductive condition and quality to males in the Lake Eyre dragon lizard, Ctenophorus maculosus. Females of this species develop intense orange ventral coloration when sexually receptive, which fades to white only after laying. To separate the effect of colour and behaviour, we manipulated the presence of female orange ventral colouration within different periods of the reproductive cycle in which females display qualitatively different behaviours. In a separate manipulation, we tested whether the presence of an ultraviolet (UV component, size and intensity of female orange patches influenced male courtship investment. Males tended to chase, bite and copulate more with orange than white females, irrespective of reproductive state. However, males copulated much more frequently with receptive females than non-receptive or gravid females, consistent with females’ behavioural acceptance of copulations during this stage. Males courted females with small orange patches the most, and had an overall preference for intense colour patches (as opposed to pale orange patches, regardless of the presence of UV. Our results suggest that female orange coloration signals reproductive condition, specifically receptivity, and that small, intensely orange patches signal that females are more likely to be receptive. Female ornamentation therefore encodes information used by males to make decisions regarding courtship investment.

  5. Proximate determinants of bite force in Anolis lizards.

    Science.gov (United States)

    Wittorski, Antoine; Losos, Jonathan B; Herrel, Anthony

    2016-01-01

    Performance measures associated with the vertebrate jaw system may provide important insights into vertebrate ecology and evolution because of their importance in many ecologically relevant tasks. Previous studies have shown that in many taxa, evolution toward higher bite force has gone hand in hand with the evolution of larger body size. However, independent of differences in overall body size, bite force may vary depending on head size and shape as well. Moreover, the underlying musculature may also drive variation in bite force. Here, we investigate the proximate determinants of bite force in lizards of the genus Anolis. We dissected the jaw muscles and quantified muscle mass, fibre length, and cross-sectional area. Data were analysed for both sexes independently given the sexual dimorphism detected in the dataset. Our results show that the traits that explain bite force are similar in both males and females with overall body size and muscle mass being the principal determinants. Among the different muscles examined, the adductor externus and the pseudotemporalis groups were the best determinants of bite force. However, models run for males predicted the variation in bite force better than models for females, suggesting that selection on morphology improving bite force may be stronger in males. © 2015 Anatomical Society.

  6. Evidence for facilitated lactate uptake in lizard skeletal muscle.

    Science.gov (United States)

    Donovan, E R; Gleeson, T T

    2001-12-01

    To understand more fully lactate metabolism in reptilian muscle, lactate uptake in lizard skeletal muscle was measured and its similarities to the monocarboxylate transport system found in mammals were examined. At 2 min, uptake rates of 15 mmol l(-1) lactate into red iliofibularis (rIF) were 2.4- and 2.2-fold greater than white iliofibularis (wIF) and mouse soleus, respectively. alpha-Cyano-4-hydroxycinnamate (15 mmol l(-1)) caused little inhibition of uptake in wIF but caused a 42-54 % reduction in the uptake rate of lactate into rIF, suggesting that much of the lactate uptake by rIF is via protein-mediated transport. N-ethymaleimide (ETH) (10 mmol l(-1)) also caused a reduction in the rate of uptake, but measurements of adenylate and phosphocreatine concentrations show that ETH had serious effects on rIF and wIF and may not be appropriate for transport inhibition studies in reptiles. The higher net uptake rate by rIF than by wIF agrees with the fact that rIF shows much higher rates of lactate utilization and incorporation into glycogen than wIF. This study also suggests that lactate uptake by reptilian muscle is similar to that by mammalian muscle and that, evolutionarily, this transport system may be relatively conserved even in animals with very different patterns of lactate metabolism.

  7. Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Haider Abbas Khwaja

    2015-08-01

    Full Text Available Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM and Laser Scanning Microscopy (LSM analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0. Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies.

  8. Extinction, reintroduction, and restoration of a lizard meta-population equilibrium in the Missouri Ozarks.

    Science.gov (United States)

    Sites, Jack W

    2013-07-01

    In this issue of Molecular Ecology, Neuwald & Templeton (2013) report on a 22-year study of natural populations of Collared Lizards (Crotaphytus collaris) that evolved on isolated on rock outcrops (‘glades’) in the Ozark Mountains in eastern Missouri. This ecosystem was originally maintained by frequent fires that kept the forest understory open, but fire-suppression was adopted as official policy in about 1945, which led to a loss of native biodiversity, including local extinctions of some lizard populations. Policies aimed at restoring biodiversity included controlled burns and re-introductions of lizards to some glades, which began in 1984. Populations were monitored from 1984–2006, and demographic and genetic data collected from 1 679 lizards were used to documents shifts in meta-population dynamics over four distinct phases of lizard recovery: 1–an initial translocation of lizards drawn from the same source populations onto three glades that were likely part of one metapopulation; 2–a period of isolation and genetic drift associated with the absence of fires; 3–a period of rapid colonization and population increase following restoration of fire; and 4–stabilization of the meta-population under regular prescribed burning. This study system thus provides a rare opportunity to characterize the dynamics of a landscape-scale management strategy on the restoration of the meta-population of a reintroduced species; long-term case studies of the extinction, founding, increase, and stabilization of a well-defined meta-population, based on both demographic and population genetic data, are rare in the conservation, ecological, and evolutionary literature.

  9. The importance of remnant native vegetation of Amazonian submontane forest for the conservation of lizards

    Directory of Open Access Journals (Sweden)

    DJ Silva

    Full Text Available Forest fragmentation affects animal population dynamics mainly by loss of habitat and disruption of animal movement. Lizard assemblages are affected by environmental changes, but, depending on their ecological needs, some species might be more vulnerable than others. The southern Amazon suffers accelerated anthropic actions replacing natural environments by farmland (crops and pasture. This region is considerably drier than most of the northern Amazon, with stational semi-deciduous forests fragmented and isolated by pasture, and crops to a lesser extent. Here we report data on lizard assemblages using semi-deciduous forests, forest edge and the surrounding pasture in the southern Amazon in Mato Grosso, Brazil. Lizards were collected in 21 forest fragments (41 to 7,035 ha surrounded by pasture; using pitfall traps placed on a degradation gradient – from pasture inwards forest fragment (up to 200 m. We collected 242 individuals (14 species, seven families in 6,300 trap-days. The pattern of species occurrence was largely nested and this nesting was associated with three habitat guilds (generalist, edge-tolerant, and forest species. Although there was no obvious fragmentation effect on lizards diversity community-wise, Hoplocercus spinosus, Bachia dorbignyi, Micrablepharus maximiliani and Kentropyx calcarta were more vulnerable to such effects than all other ten species collected. We verified that assemblages inhabiting pasture and forest edge are a nested subset of assemblages from the forest core. The remnant native vegetation is not distributed homogeneously and lizards species can persist in different parts of the landscape, therefore we recommend the protection of forest remnants as an important conservation action for lizards of the southern Amazon.

  10. Phenotypic shifts in urban areas in the tropical lizard Anolis cristatellus.

    Science.gov (United States)

    Winchell, Kristin M; Reynolds, R Graham; Prado-Irwin, Sofia R; Puente-Rolón, Alberto R; Revell, Liam J

    2016-05-01

    Urbanization is an increasingly important dimension of global change, and urban areas likely impose significant natural selection on the species that reside within them. Although many species of plants and animals can survive in urban areas, so far relatively little research has investigated whether such populations have adapted (in an evolutionary sense) to their newfound milieu. Even less of this work has taken place in tropical regions, many of which have experienced dramatic growth and intensification of urbanization in recent decades. In the present study, we focus on the neotropical lizard, Anolis cristatellus. We tested whether lizard ecology and morphology differ between urban and natural areas in three of the most populous municipalities on the island of Puerto Rico. We found that environmental conditions including temperature, humidity, and substrate availability differ dramatically between neighboring urban and natural areas. We also found that lizards in urban areas use artificial substrates a large proportion of the time, and that these substrates tend to be broader than substrates in natural forest. Finally, our morphological data showed that lizards in urban areas have longer limbs relative to their body size, as well as more subdigital scales called lamellae, when compared to lizards from nearby forested habitats. This shift in phenotype is exactly in the direction predicted based on habitat differences between our urban and natural study sites, combined with our results on how substrates are being used by lizards in these areas. Findings from a common-garden rearing experiment using individuals from one of our three pairs of populations provide evidence that trait differences between urban and natural sites may be genetically based. Taken together, our data suggest that anoles in urban areas are under significant differential natural selection and may be evolutionarily adapting to their human-modified environments.

  11. The importance of remnant native vegetation of Amazonian submontane forest for the conservation of lizards.

    Science.gov (United States)

    Silva, D J; Santos-Filho, M; Canale, G R

    2014-08-01

    Forest fragmentation affects animal population dynamics mainly by loss of habitat and disruption of animal movement. Lizard assemblages are affected by environmental changes, but, depending on their ecological needs, some species might be more vulnerable than others. The southern Amazon suffers accelerated anthropic actions replacing natural environments by farmland (crops and pasture). This region is considerably drier than most of the northern Amazon, with stational semi-deciduous forests fragmented and isolated by pasture, and crops to a lesser extent. Here we report data on lizard assemblages using semi-deciduous forests, forest edge and the surrounding pasture in the southern Amazon in Mato Grosso, Brazil. Lizards were collected in 21 forest fragments (41 to 7,035 ha) surrounded by pasture; using pitfall traps placed on a degradation gradient - from pasture inwards forest fragment (up to 200 m). We collected 242 individuals (14 species, seven families) in 6,300 trap-days. The pattern of species occurrence was largely nested and this nesting was associated with three habitat guilds (generalist, edge-tolerant, and forest species). Although there was no obvious fragmentation effect on lizards diversity community-wise, Hoplocercus spinosus, Bachia dorbignyi, Micrablepharus maximiliani and Kentropyx calcarta were more vulnerable to such effects than all other ten species collected. We verified that assemblages inhabiting pasture and forest edge are a nested subset of assemblages from the forest core. The remnant native vegetation is not distributed homogeneously and lizards species can persist in different parts of the landscape, therefore we recommend the protection of forest remnants as an important conservation action for lizards of the southern Amazon.

  12. Another look at the BL Lacertae flux and spectral variability. Observations by GASP-WEBT, XMM-Newton, and Swift in 2008-2009

    Science.gov (United States)

    Raiteri, C. M.; Villata, M.; Bruschini, L.; Capetti, A.; Kurtanidze, O. M.; Larionov, V. M.; Romano, P.; Vercellone, S.; Agudo, I.; Aller, H. D.; Aller, M. F.; Arkharov, A. A.; Bach, U.; Berdyugin, A.; Blinov, D. A.; Böttcher, M.; Buemi, C. S.; Calcidese, P.; Carosati, D.; Casas, R.; Chen, W.-P.; Coloma, J.; Diltz, C.; di Paola, A.; Dolci, M.; Efimova, N. V.; Forné, E.; Gómez, J. L.; Gurwell, M. A.; Hakola, A.; Hovatta, T.; Hsiao, H. Y.; Jordan, B.; Jorstad, S. G.; Koptelova, E.; Kurtanidze, S. O.; Lähteenmäki, A.; Larionova, E. G.; Leto, P.; Lindfors, E.; Ligustri, R.; Marscher, A. P.; Morozova, D. A.; Nikolashvili, M. G.; Nilsson, K.; Ros, J. A.; Roustazadeh, P.; Sadun, A. C.; Sillanpää, A.; Sainio, J.; Takalo, L. O.; Tornikoski, M.; Trigilio, C.; Troitsky, I. S.; Umana, G.

    2010-12-01

    Aims: In a previous study we suggested that the broad-band emission and variability properties of BL Lacertae can be accounted for by a double synchrotron emission component with related inverse-Compton emission from the jet, plus thermal radiation from the accretion disc. Here we investigate the matter with further data extending over a wider energy range. Methods: The GLAST-AGILE Support Program (GASP) of the whole earth blazar telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies to follow its flux behaviour. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. Results: The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate (~4-7%) flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting regions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The

  13. Pattern formation - Instabilities in sand ripples

    DEFF Research Database (Denmark)

    Hansen, J. L.; v. Hecke, M.; Haaning, A.

    2001-01-01

    Sand ripples are seen below shallow wavy water and are formed whenever water oscillates over a bed of sand. Here we analyse the instabilities that can upset this perfect patterning when the ripples are subjected to large changes in driving amplitude or frequency, causing them to deform both...

  14. Pilot Project Sand Groynes Delfland Coast

    NARCIS (Netherlands)

    Hoekstra, R.; Walstra, D.J.R.; Swinkels, C.S.

    2012-01-01

    In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of

  15. Silica sand resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Westerhoff, W.E.; Menkovic, A.; Gruijters, S.H.L.L.; Dubelaar, C.W.; Maljers, D.

    2009-01-01

    Silica sand, (almost) pure quartz sand, is a valuable and scarce mineral resource within the shallow Dutch subsurface. High-grade deposits are exploited in the southeastemmost part of the country, as raw material for the glass, ceramic, chemical and other process industries. Dutch land-use policy re

  16. Pilot Project Sand Groynes Delfland Coast

    NARCIS (Netherlands)

    Hoekstra, R.; Walstra, D.J.R.; Swinkels, C.S.

    2012-01-01

    In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of

  17. Understanding Colombian Amazonian white sand forests

    NARCIS (Netherlands)

    Peñuela-Mora, M.C.

    2014-01-01

    Although progress has been made in studies on white sand forests in the Amazon, there is still a considerable gap in our knowledge of the unique species composition of white sand forests and their structure and dynamics, especially in Western Amazon. This thesis aims to fill this gap by addressing t

  18. Sand transportation and reverse patterns over leeward face of sand dune

    Science.gov (United States)

    Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning

    2017-04-01

    Sand saltation has complex interactions with turbulent flow and dune form. Most models of wind-blown sand consider ideal circumstances such as steady wind velocity and a flat surface, and the bulk of data on wind flow and sand transport over an individual dune has focused mostly on the influence of dune shape or inter-dune space on the wind flow, neglecting the effect of morphology on sand saltation, particularly airflow and sand transportation over the leeward slope. Wind flow structures over the leeward slope of sand dunes have a fundamental influence on the organization of sand dunes. In order to understand sand dune dynamics, lee face airflow and sediment transportation should be paid more attention. Previous field observations could not measure turbulent flow structure well because of the limited observation points and the influence of experiment structure on wind field. In addition, the reverse sand particles over leeward face could not be collected by sand trap in field. Numerous field observations could not measure turbulent flow structure because of the limited observation points and the influence of experimental structures on the wind field. In addition, the reverse transport of sand particles over leeward face could not be collected by sand traps in field. Therefore, this paper aims to investigate the turbulent flow structure and sand transport pattern over the leeward slope. A numerical model of sand saltation over slope terrain is constructed, which also considers the coupling effects between air flow and sand particles. The large eddy simulation method is used to model turbulent flow. Sand transport is simulated by tracking the trajectory of each sand particle. The results show that terrain significantly alters the turbulent air flow structure and wind-blown sand movement, especially over the leeward slope. Here, mass flux increases initially and then decreases with height in the reversed flow region in the direction of wind flow, and the mass flux

  19. Yolk coelomitis in a white-throated monitor lizard (Varanus albigularis : short communication

    Directory of Open Access Journals (Sweden)

    B.R. Gardner

    2010-05-01

    Full Text Available Yolk coelomitis as a result of pre-ovulatory follicular stasis is a common disorder in captive reptiles, especially in captive lizards of various genera. The clinical signs are generally fairly non-specific and diagnosis is based on clinical signs together with most of the common diagnostic modalities. The condition is most likely a husbandry and environment-related reproductive disorder. It has not been reported in wild free-living specimens. This report describes the clinical presentation and post mortem lesions in a white-throated monitor lizard that died during treatment for non-specific clinical signs related to a severe yolk coelomitis.

  20. Male Texas Horned Lizards increase daily movements and area covered in spring: A mate searching strategy?

    Science.gov (United States)

    Stark, Richard C.; Fox, S. F.; David, M.L.

    2005-01-01

    Texas Horned Lizards, Phrynosoma cornutum, were tracked using fluorescent powder to determine exact daily movements. Daily linear movements and daily space use were compared between adult males and females. Lizards that traveled the greatest linear distances also covered the largest areas. In Oklahoma, adults emerge from hibernation in late April and early May and mate soon afterward. Males traveled significantly greater distances (and covered significantly larger areas in a day) than females in May but not after May. We propose that males move more and cover more area than females early in the mating season to intercept receptive females. Copyright 2005 Society for the Study of Amphibians and Reptiles.

  1. Beta-endorphin disrupts seasonal and FSH-induced ovarian recrudescence in the lizard Mabuya carinata.

    Science.gov (United States)

    Ganesh, C B; Yajurvedi, H N

    2003-10-01

    Administration (ip) of an opioid peptide, beta-endorphin (beta-EP) (0.1, 0.5, or 1 microg beta-EP/day/lizard for 30 days) during seasonal recrudescence phase of the ovarian cycle inhibited ovarian recrudescence as shown by the absence of vitellogenic follicles in the ovary in contrast to their presence in treatment controls in the lizard Mabuya carinata. In the germinal bed, treatment of 0.1 microg beta-EP did not affect primordial follicles, whereas their mean number was significantly lower in lizards treated with 0.5 or 1 microg beta-EP compared to those of treatment controls. There was also suppression of oviductal development as shown by a significantly lower relative weight of the oviduct and regressed oviductal glands in lizards treated with all the dosages of beta-EP compared to treatment controls. In another experiment, administration of FSH (10 IU FSH/alternate day/lizard for 30 days) during the regression phase of the ovarian cycle induced development of vitellogenic follicles, whereas the treatment controls showed only previtellogenic follicles. In addition, there was a significant increase in the ovarian and oviductal weights compared to initial and treatment controls. However, simultaneous administration of similar dosage of FSH and beta-EP (0.5 microg/day/lizard) did not induce ovarian recrudescence as shown by the absence of vitellogenic follicles in the ovary and significantly lower weight of the ovary and the oviduct and the mean number of oogonia, oocytes, and primordial follicles compared to those of FSH-treated lizards. The results indicate that beta-EP inhibits seasonal as well as FSH-induced ovarian recrudescence. Inhibitory effect of beta-EP on follicular development despite FSH administration implies its effect at the ovarian level in M. carinata. While adversely affecting the ovarian follicular development, beta-EP did not affect the adrenal gland as there was no significant variation in the mean nuclear diameter of the adrenocortical cells

  2. Natural history of Xenosaurus phalaroanthereon (Squamata, Xenosauridae, a Knob-scaled Lizard from Oaxaca, Mexico

    Directory of Open Access Journals (Sweden)

    Julio A. Lemos-Espinal

    2005-12-01

    Full Text Available We made observations on the natural history of a population of the lizard Xenosaurus phalaroanthereon from Oaxaca, Mexico. Females were larger than males (SVL. Most lizards were found completely inside rock crevices. Mean body temperature was 20.3°C. Body temperature wasrelated primarily to substrate temperature. Body temperature was not influenced by any crevice characteristic. Based on abdominal palpation, the size at maturity for females appears to be 117-119 mm SVL. Sex ratio did not differ from 1:1. We compare the ecology of this population to that of other Xenosaurus.

  3. Identification key to species of the flying lizard genus Draco Linnaeus, 1758 (Squamata: Agamidae in Thailand

    Directory of Open Access Journals (Sweden)

    Nattawut Srichairat

    2017-02-01

    Full Text Available A species identification key of flying lizards in the genus Draco from Thailand was constructed based on 521 preserved specimens from collections during 1967–2012 in the Natural History Museum (THNHM, National Science Museum, Technopolis, Pathum Thani, Thailand. Regardless of sexual characters, four characters were used to identify Draco spp. lizards: 1 nostril direction; 2 type of tympanum; 3 pattern of patagium; and 4 snout with or without a series of scales forming a Y-shaped figure. The specimens were identified into nine species—Draco blanfordii, Draco fimbriatus, Draco maculatus, Draco maximus, Draco melanopogon, Draco obscurus, Draco quinquefasciatus, Draco taeniopterus and Draco volans.

  4. Choosing an optimum sand control method

    Directory of Open Access Journals (Sweden)

    Ehsan Khamehchi

    2015-06-01

    Full Text Available Formation sand control is always one of the main concerns of production engineers. There are some different methods to prevent sand production. Choosing a method for preventing formation sand production depends on different reservoir parameters and politic and economic conditions. Sometimes, economic and politic conditions are more effective to choose an optimum than reservoir parameters. Often, simultaneous investigation of politic and economic conditions with reservoir parameters has different results with what is expected. So, choosing the best sand control method is the result of thorough study. Global oil price, duration of sand control project and costs of necessary equipment for each method as economic and politic conditions and well productivity index as reservoir parameter are the main parameters studied in this paper.

  5. Altitude of the top of the Sparta Sand and Memphis Sand in three areas of Arkansas

    Science.gov (United States)

    Pugh, Aaron L.; Westerfield, Paul W.; Gonthier, Gerard; Poynter, David T.

    1998-01-01

    The Sparta Sand and Memphis Sand form the second most productive aquifer in Arkansas. The Sparta Sand and Memphis Sand range in thick- ness from 0 to 900 feet, consisting of fine- to medium-grained sands interbedded with layers of silt, clay, shale, and minor amounts of lignite. Within the three areas of interest, the top surface of the Sparta Sand and Memphis Sand dips regionally east and southeast towards the axis of the Mississippi Embayment syncline and Desha Basin. Local variations in the top surface may be attributed to a combination of continued development of structural features, differential compaction, localized faulting, and erosion of the surface prior to subsequent inundation and deposition of younger sediments.

  6. Sand Failure Mechanism and Sanding Parameters in Niger Delta Oil Reservoirs

    Directory of Open Access Journals (Sweden)

    Sunday Isehunwa,

    2010-05-01

    Full Text Available Sand production is a major issue during oil and gas production from unconsolidated reservoirs. In predicting the onset of sand production, it is important to accurately determine the failure mechanism and the contributing parameters. The aim of this study was to determine sand failure mechanism in the Niger-Delta, identify themajor contributing parameters and evaluate their effects on sanding.Completion and production data from 78 strings completed on 22 reservoirs in a Niger Delta oil Field were evaluated. Sand failure mechanisms and contributing parameters were identified and compared with published profiles. The results showed that cohesive stress is the predominant sand failure mechanism. Water cut, bean size and gas oil ratio (GOR impact sand production in the Niger Delta.

  7. Global sand trade is paving the way for a tragedy of the sand commons

    Science.gov (United States)

    Torres, A.; Brandt, J.; Lear, K.; Liu, J.

    2016-12-01

    In the first 40 years of the 21st century, planet Earth is highly likely to experience more urban land expansion than in all of history, an increase in transportation infrastructure by more than a third, and a great variety of land reclamation projects. While scientists are beginning to quantify the deep imprint of human infrastructure on biodiversity at large scales, its off-site impacts and linkages to sand mining and trade have been largely ignored. Sand is the most widely used building material in the world. With an ever-increasing demand for this resource, sand is being extracted at rates that far exceed its replenishment, and is becoming increasingly scarce. This has already led to conflicts around the world and will likely lead to a "tragedy of the sand commons" if sustainable sand mining and trade cannot be achieved. We investigate the environmental and socioeconomic interactions over large distances (telecouplings) of infrastructure development and sand mining and trade across diverse systems through transdisciplinary research and the recently proposed telecoupling framework. Our research is generating a thorough understanding of the telecouplings driven by an increasing demand for sand. In particular, we address three main research questions: 1) Where are the conflicts related to sand mining occurring?; 2) What are the major "sending" and "receiving" systems of sand?; and 3) What are the main components (e.g. causes, effects, agents, etc.) of telecoupled systems involving sand mining and trade? Our results highlight the role of global sand trade as a driver of environmental degradation that threatens the integrity of natural systems and their capacity to deliver key ecosystem services. In addition, infrastructure development and sand mining and trade have important implications for other sustainability challenges such as over-fishing and global warming. This knowledge will help to identify opportunities and tools to better promote a more sustainable use

  8. Are Invasive Species Stressful? The Glucocorticoid Profile of Native Lizards Exposed to Invasive Fire Ants Depends on the Context.

    Science.gov (United States)

    Graham, Sean P; Freidenfelds, Nicole A; Thawley, Christopher J; Robbins, Travis R; Langkilde, Tracy

    Invasive species represent a substantial threat to native species worldwide. Research on the impacts of invasive species on wild living vertebrates has focused primarily on population-level effects. The sublethal, individual-level effects of invaders may be equally important but are poorly understood. We investigated the effects of invasive fire ants (Solenopsis invicta) on the physiological stress response of a native lizard (Sceloporus undulatus) within two experimental contexts: directly exposing lizards to a fire ant attack and housing lizards with fire ants in seminatural field enclosures. Lizards directly exposed to brief attack by fire ants had elevated concentrations of the stress hormone corticosterone (CORT), suggesting that these encounters can be physiologically stressful. However, lizards exposed for longer periods to fire ants in field enclosures had lower concentrations of CORT. This may indicate that the combined effects of confinement and fire ant exposure have pushed lizards into allostatic overload. However, lizards from fire ant enclosures appeared to have intact negative feedback controls of the stress response, evidenced by functioning adrenocorticotropic hormone responsiveness and lack of suppression of innate immunity (plasma bactericidal capacity). We review previous studies examining the stress response of wild vertebrates to various anthropogenic stressors and discuss how these-in combination with our results-underscore the importance of considering context (the length, frequency, magnitude, and types of threat) when assessing these impacts.

  9. Effects of wildfire, rainfall and region on desert lizard assemblages: the importance of multi-scale processes.

    Science.gov (United States)

    Pastro, Louise A; Dickman, Christopher R; Letnic, Mike

    2013-10-01

    Vertebrate populations are influenced by environmental processes that operate at a range of spatial and temporal scales. Wildfire is a disturbance that can affect vertebrate populations across large spatial scales, although vertebrate responses are frequently influenced by processes operating at smaller spatial scales such as topography, interspecific interactions and regional history. Here, we investigate the effects of a broad-scale wildfire on lizard assemblages in a desert region. We predicted that a rainfall gradient within the region affected by the wildfire would influence lizard responses to the fire by encouraging post-fire succession to proceed more rapidly in high-rainfall areas, and would be enabled in turn by more rapid vegetation recovery. To test our prediction, we censused lizards, measured rainfall, undertook vegetation surveys and sampled invertebrate abundance across burnt and unburnt habitat ecotones within three regional areas situated along a gradient of long-term annual rainfall. Lizard diversity was not affected by fire or region and lizard abundance was influenced only by region. Lizard assemblage composition was also only influenced by region, but this did not relate to differences in rainfall or habitat as we had predicted. Regional differences in lizard assemblages related instead to food availability. The observed differences also likely reflected regional differences in the strength of biotic interactions with predators and changes in land use. Our study shows that assemblage responses to a disturbance were not uniform within a large desert region and instead were influenced by other environmental processes operating simultaneously at multiple temporal and spatial scales.

  10. Lizard movement tracks: variation in path re-use behaviour is consistent with a scent-marking function

    Directory of Open Access Journals (Sweden)

    Stephan T. Leu

    2016-03-01

    Full Text Available Individual movement influences the spatial and social structuring of a population. Animals regularly use the same paths to move efficiently to familiar places, or to patrol and mark home ranges. We found that Australian sleepy lizards (Tiliqua rugosa, a monogamous species with stable pair-bonds, repeatedly used the same paths within their home ranges and investigated whether path re-use functions as a scent-marking behaviour, or whether it is influenced by site familiarity. Lizards can leave scent trails on the substrate when moving through the environment and have a well-developed vomeronasal system to detect and respond to those scents. Path re-use would allow sleepy lizards to concentrate scent marks along these well-used trails, advertising their presence. Hypotheses of mate attraction and mating competition predict that sleepy lizard males, which experience greater intra-sexual competition, mark more strongly. Consistent with those hypotheses, males re-used their paths more than females, and lizards that showed pairing behaviour with individuals of the opposite sex re-used paths more than unpaired lizards, particularly among females. Hinterland marking is most economic when home ranges are large and mobility is low, as is the case in the sleepy lizard. Consistent with this strategy, re-used paths were predominantly located in the inner 50% home range areas. Together, our detailed movement analyses suggest that path re-use is a scent marking behaviour in the sleepy lizard. We also investigated but found less support for alternative explanations of path re-use behaviour, such as site familiarity and spatial knowledge. Lizards established the same number of paths, and used them as often, whether they had occupied their home ranges for one or for more years. We discuss our findings in relation to maintenance of the monogamous mating system of this species, and the spatial and social structuring of the population.

  11. The relationship between the lizard eye and associated bony features: a cautionary note for interpreting fossil activity patterns.

    Science.gov (United States)

    Hall, Margaret I

    2009-06-01

    Activity pattern, the time of day when an animal is active, is associated with ecology. There are two major activity patterns: diurnal (awake during the day in a photopic environment) and nocturnal (awake at night in a scotopic environment). Lizards exhibit characteristic eye shapes associated with activity pattern, with scotopic-adapted lizard eyes optimized for visual sensitivity with large corneal diameters relative to their eye axial lengths, and photopic-adapted lizards optimized for visual acuity, with larger axial lengths of the eye relative to their corneal diameters. This study: (1) quantifies the relationship between the lizard eye and its associated bony anatomy (the orbit, sclerotic ring, and associated skull widths); (2) investigates how activity pattern is reflected in that bony anatomy; and (3) determines if it is possible to reliably interpret activity pattern for a lizard that does not have the soft tissue available for study, specifically, for a fossil. Knowledge of extinct lizards' activity patterns would be useful in making paleoecological interpretations. Here, 96 scotopic- and photopic-adapted lizard species are analyzed in a phylogenetic context. Although there is a close relationship between the lepidosaur eye and associated bony anatomy, based on these data activity pattern cannot be reliably interpreted for bony-only specimens, such as a fossil, possibly because of the limited ossification of the lepidosaur skull. Caution should be exercised when utilizing lizard bony anatomy to interpret light-level adaptation, either for a fossil lizard or as part of an extant phylogenetic bracket to interpret other extinct animals with sclerotic rings, such as dinosaurs.

  12. Lizard movement tracks: variation in path re-use behaviour is consistent with a scent-marking function.

    Science.gov (United States)

    Leu, Stephan T; Jackson, Grant; Roddick, John F; Bull, C Michael

    2016-01-01

    Individual movement influences the spatial and social structuring of a population. Animals regularly use the same paths to move efficiently to familiar places, or to patrol and mark home ranges. We found that Australian sleepy lizards (Tiliqua rugosa), a monogamous species with stable pair-bonds, repeatedly used the same paths within their home ranges and investigated whether path re-use functions as a scent-marking behaviour, or whether it is influenced by site familiarity. Lizards can leave scent trails on the substrate when moving through the environment and have a well-developed vomeronasal system to detect and respond to those scents. Path re-use would allow sleepy lizards to concentrate scent marks along these well-used trails, advertising their presence. Hypotheses of mate attraction and mating competition predict that sleepy lizard males, which experience greater intra-sexual competition, mark more strongly. Consistent with those hypotheses, males re-used their paths more than females, and lizards that showed pairing behaviour with individuals of the opposite sex re-used paths more than unpaired lizards, particularly among females. Hinterland marking is most economic when home ranges are large and mobility is low, as is the case in the sleepy lizard. Consistent with this strategy, re-used paths were predominantly located in the inner 50% home range areas. Together, our detailed movement analyses suggest that path re-use is a scent marking behaviour in the sleepy lizard. We also investigated but found less support for alternative explanations of path re-use behaviour, such as site familiarity and spatial knowledge. Lizards established the same number of paths, and used them as often, whether they had occupied their home ranges for one or for more years. We discuss our findings in relation to maintenance of the monogamous mating system of this species, and the spatial and social structuring of the population.

  13. Thermal dependence of passive electrical properties of lizard muscle fibres.

    Science.gov (United States)

    Adams, B A

    1987-11-01

    1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15-35 degrees C) and Sceloporus occidentalis (15-40 degrees C), and for twitch fibres from the white (15-45 degrees C) and red (15-40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases.

  14. Anolis lizards as biocontrol agents in mainland and island agroecosystems.

    Science.gov (United States)

    Monagan, Ivan V; Morris, Jonathan R; Davis Rabosky, Alison R; Perfecto, Ivette; Vandermeer, John

    2017-04-01

    Our knowledge of ecological interactions that bolster ecosystem function and productivity has broad applications to the management of agricultural systems. Studies suggest that the presence of generalist predators in agricultural landscapes leads to a decrease in the abundance of herbivorous pests, but our understanding of how these interactions vary across taxa and along gradients of management intensity and eco-geographic space remains incomplete. In this study, we assessed the functional response and biocontrol potential of a highly ubiquitous insectivore (lizards in the genus Anolis) on the world's most important coffee pest, the coffee berry borer (Hypothalemus hampei). We conducted field surveys and laboratory experiments to examine the impact of land-use intensification on species richness and abundance of anoles and the capacity of anoles to reduce berry borer infestations in mainland and island coffee systems. Our results show that anoles significantly reduce coffee infestation rates in laboratory settings (Mexico, p = .03, F = 5.13 df = 1, 35; Puerto Rico, p = .014, F = 8.82, df = 1, 10) and are capable of consuming coffee berry borers in high abundance. Additionally, diversified agroecosystems bolster anole abundance, while high-intensity practices, including the reduction of vegetation complexity and the application of agrochemicals were associated with reduced anole abundance. The results of this study provide supporting evidence of the positive impact of generalist predators on the control of crop pests in agricultural landscapes, and the role of diversified agroecosystems in sustaining both functionally diverse communities and crop production in tropical agroecosystems.

  15. Convergent evolution of brain morphology and communication modalities in lizards

    Institute of Scientific and Technical Information of China (English)

    Christopher D.ROBINSON; Michael S.PATTON; Brittney M.ANDRE; Michele A.JOHNSON

    2015-01-01

    Animals communicate information within their environments via visual,chemical,auditory,and/or tactile modalities.The use of each modalityis generally linked to particular brain regions,but it is not yet known whether the cellular morphology of neurons in these regions has evolved in association with the relative use of a modality.We investigated relationships between the behavioral use of communication modalities and neural morphologies in six lizard species.Two of these species (Anolis carolinensis and Leiocephalus carinatus) primarily use visual signals to communicate with conspecifics and detect potential prey,and two (Aspidoscelis gularis and Scincella lateralis) communicate and forage primarily using chemical signals.Two other species (Hemidactylus turcicus and Sceloporus olivaceus) use both visual and chemical signals.For each species,we performed behavioral observations and quantified rates of visual and chemical behaviors.We then cryosectioned brain tissues from 9-10 males of each species and measured the soma size and density of neurons in two brain regions associated with visual behaviors (the lateral geniculate nucleus and the nucleus rotundus) and one region associated with chemical behaviors (the nucleus sphericus).With analyses conducted in a phylogenetic context,we found that species that performed higher rates of visual displays had a denser lateral geniculatc nucleus,and species that used a higher proportion of chemical displays had larger somas in the nucleus sphericus.These relationships suggest that neural morphologies in the brain have evolved convergently in species with similar communication behaviors [Current Zoology 61 (2):281-291,2015].

  16. Adsorption of dyes on Sahara desert sand.

    Science.gov (United States)

    Varlikli, Canan; Bekiari, Vlasoula; Kus, Mahmut; Boduroglu, Numan; Oner, Ilker; Lianos, Panagiotis; Lyberatos, Gerasimos; Icli, Siddik

    2009-10-15

    Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques. It was found that water-soluble kyanite, which is detected in natural sand, is the dominant factor affecting adsorbance of cationic dyes. The sand adsorbs over 75% of cationic dyes but less than 21% for anionic ones. Among the dyes studied, Methylene Blue (MB) demonstrated the strongest affinity for Sahara desert sand (Q(e)=11.98 mg/g, for initial dye solution concentration 3.5 x 10(-5)mol/L). The effects of initial dye concentration, the amount of the adsorbent, the temperature and the pH of the solution on adsorption capacity were tested by using Methylene Blue as model dye. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied. It was concluded that adsorption of Methylene Blue on Sahara desert sand followed pseudo-second order kinetics. Gibbs free energy, enthalpy change and entropy change were calculated and found -6411 J/mol, -30360 J/mol and -76.58 J/mol K, respectively. These values indicate that the adsorption is an exothermic process and has a spontaneous nature at low temperatures.

  17. Critical state of sand matrix soils.

    Science.gov (United States)

    Marto, Aminaton; Tan, Choy Soon; Makhtar, Ahmad Mahir; Kung Leong, Tiong

    2014-01-01

    The Critical State Soil Mechanic (CSSM) is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803-0.998, 0.144-0.248, and 1.727-2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated.

  18. Sand Flies and Their Control Methods.

    Science.gov (United States)

    Çetin, Hüseyin; Özbel, Yusuf

    2017-06-01

    The main aim of managing arthropod vectors that carry the disease agents is interrupting the infection cycle. Therefore, the management of the disease implies that all precautions related to all elements (i.e., human, arthropod vector, and reservoir) in the infection cycle need to be taken. There are important points that need to be considered while dealing with sand flies (Diptera: Psychodidae: Phlebotominae), which in many regions worldwide, particularly in tropical and subtropical areas, are vectors of diseases such as leishmaniasis and sand fly fever and are the arthropods of the infection cycle. Because the larval control of the sand flies is very difficult and almost impossible, the management is mainly conducted for the adults. The most effective strategy for reducing both sand fly fever and leishmaniasis is managing sand flies, particularly in areas where humans are located. In this review, the morphology, biology, and taxonomy of sand flies; the integrated fighting and management methods such as insecticide-impregnated bed nets and use of curtains, zooprophylaxis, indoor and outdoor residual applications, larvicides, repellents, and insecticide-impregnated dog collars; and data regarding many issues such as insecticide resistance in sand flies have been emphasized on in the review.

  19. Critical State of Sand Matrix Soils

    Directory of Open Access Journals (Sweden)

    Aminaton Marto

    2014-01-01

    Full Text Available The Critical State Soil Mechanic (CSSM is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803–0.998, 0.144–0.248, and 1.727–2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated.

  20. Survey of the reptilian fauna of the Kingdom of Saudi Arabia. V. The lizard fauna of Turaif region.

    Science.gov (United States)

    Al-Sadoon, Mohammed K; Paray, Bilal Ahmad; Al-Otaibi, Hamad S

    2016-09-01

    Turaif area located in the Northern border region of Saudi Arabia is one of the most important regions of the Kingdom. This work was proposed to throw light on the diversity of lizard fauna investigated through the collection and subsequent identification of specimens from different localities of Turaif region of Kingdom of Saudi Arabia. Sixteen species of lizards belonging to 5 families (Agamidae, Gekkonidae, Lacertidae, Scincidae and Varanidae) were recorded. Lacertidae was the most common family. Three species of lizards namely Acanthodactylus orientalis, Acanthodactylus scutellatus and Acanthodactylus grandis were reported for the first time in the Turaif region of Saudi Arabia. The geographical distribution of the collected species within this province was mapped.

  1. Reservoir Role of Lizard Psammodromus algirus in Transmission Cycle of Borrelia burgdorferi Sensu Lato (Spirochaetaceae) in Tunisia

    OpenAIRE

    Dsouli, Najla; Younsi-kabachii, Hend; Postic, Danièle; Nouira, Said; Gern, Lise; Bouattour, Ali

    2017-01-01

    To investigate the reservoir role of the lizard Psammodromus algirus for the Lyme disease spirochete, 199 lizards were trapped from April to October 2003 in El Jouza, northwestern Tunisia. In this site, the infection rate of free-living Ixodes ricinus (L.) by Borrelia was evaluated by immunofluorescence as 34.6% for adult ticks and 12.5% for nymphs. Eighty percent of P. algirus (117/146) captured during this study were infested by I. ricinus, the predominant tick species collected from lizard...

  2. Invasive plants on disturbed Korean sand dunes

    Science.gov (United States)

    Kim, Kee Dae

    2005-01-01

    The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi- Ixeris repens, C. kobomugi- Oenothera biennis, E. mollis, Lolium multiflorum- Calystegia soldanella, and V. rotundifolia- C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic

  3. Optical variability of the BL Lacertae object GC 0109+224. Multiband behaviour and time scales from a 7-years monitoring campaign

    CERN Document Server

    Ciprini, S; Raiteri, C M; Villata, M; Ibrahimov, M A; Nucciarelli, G; Lanteri, L

    2003-01-01

    We present the most continuous data base of optical $BVR_{c}I_{c}$ observations ever published on the BL Lacertae object GC 0109+224, collected mainly by the robotic telescope of the Perugia University Observatory in the period November 1994-February 2002. These observations have been complemented by data from the Torino Observatory, collected in the period July 1995-January 1999, and Mt. Maidanak Observatory (December 2000). GC 0109+224 showed rapid optical variations and six major outbursts were observed at the beginning and end of 1996, in fall 1998, at the beginning and at the end of 2000, and at the beginning of 2002. Fast and large-amplitude drops characterized its flux behaviour. The $R_c$ magnitude ranged from 13.3 (16.16 mJy) to 16.46 (0.8 mJy), with a mean value of 14.9 (3.38 mJy). In the periods where we collected multi-filter observations, we analyzed colour and spectral indexes, and the variability patterns during some flares. The long-term behaviour seems approximatively achromatic, but during s...

  4. On the Location of the Gamma-ray Emission in the 2008 Outburst in the BL Lacertae Object AO 0235+164 through Observations across the Electromagnetic Spectrum

    CERN Document Server

    Agudo, Ivan; Jorstad, Svetlana G; Larionov, Valeri M; Gomez, Jose L; Lahteenmaki, Anne; Smith, Paul S; Nilsson, Kari; Readhead, Anthony C S; Aller, Margo F; Heidt, Jochen; Gurwell, Mark; Thum, Clemens; Wehrle, Ann E; Aller, Hugh D; Benitez, Erika; Blinov, Dmitriy A; Hagen-Thorn, Vladimir A; Hiriart, David; Jannuzi, Buell T; Joshi, Manasvita; Lindfors, Elina; Molina, Sol N; Morozova, Daria A; Nieppola, Elina; Olmstead, Alice R; Reinthal, Riho; Roca--Sogorb, Mar; Schmidt, Gary D; Sillanpaa, Aimo; Takalo, Leo; Taylor, Brian; Tornikoski, Merja; Troitsky, Ivan S; Zook, Alma C; Wiesemeyer, Helmut

    2011-01-01

    We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array (VLBA) images at 7mm with 0.15 milliarcsecond resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte-Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight ...

  5. Location of gamma-ray Flare Emission in the Jet of the BL Lacertae Object OJ287 more than 14pc from the Central Engine

    CERN Document Server

    Agudo, Ivan; Marscher, Alan P; Larionov, Valeri M; Gomez, Jose L; Lahteenmaki, Anne; Gurwell, Mark A; Smith, Paul S; Wiesemeyer, Helmut; Thum, Clemens; Heidt, Jochen; Blinov, Dmitriy A; D'Arcangelo, Francesca D; Hagen-Thorn, Vladimir A; Morozova, Daria A; Nieppola, Elina; Roca-Sogorb, Mar; Schmidt, Gary D; Taylor, Brian; Tornikoski, Merja; Troitsky, Ivan S

    2010-01-01

    We combine time-dependent multi-waveband flux and linear polarization observations with sub-milliarcsecond-scale polarimetric images at lambda=7mm of the BL Lacertae-type blazar OJ287 to locate the gamma-ray emission in prominent flares in the jet of the source >14pc from the central engine. We demonstrate a highly significant correlation between the strongest gamma-ray and millimeter-wave flares through Monte-Carlo simulations. The two reported gamma-ray peaks occurred near the beginning of two major mm-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Our Very Long Baseline Array observations indicate that the two mm-wave flares originated in the second of two features in the jet that are separated by >14 pc. The simultaneity of the peak of the higher-amplitude gamma-ray flare and the maximum in polarization of the second jet feature implies that the gamma-ray and mm-wave flares are co-spatial and occur >14 pc from the central engine. We also associate...

  6. An HST/COS Observation of Broad Ly$\\alpha$ Emission and Associated Absorption Lines of the BL Lacertae Object H 2356-309

    CERN Document Server

    Fang, Taotao; Buote, David A; Stocke, John T; Shull, J Michael; Canizares, Claude R; Gastaldello, Fabio

    2014-01-01

    Weak spectral features in BL Lacertae objects (BL Lac) often provide a unique opportunity to probe the inner region of this rare type of active galactic nucleus. We present a Hubble Space Telescope/Cosmic Origins Spectrograph observation of the BL Lac H 2356-309. A weak Ly$\\alpha$ emission line was detected. This is the fourth detection of a weak Ly$\\alpha$ emission feature in the ultraviolet (UV) band in the so-called "high energy peaked BL Lacs", after Stocke et al. Assuming the line-emitting gas is located in the broad line region (BLR) and the ionizing source is the off-axis jet emission, we constrain the Lorentz factor ($\\Gamma$) of the relativistic jet to be $\\geq 8.1$ with a maximum viewing angle of 3.6$^\\circ$. The derived $\\Gamma$ is somewhat larger than previous measurements of $\\Gamma \\approx 3 - 5$, implying a covering factor of $\\sim$ 3% of the line-emitting gas. Alternatively, the BLR clouds could be optically thin, in which case we constrain the BLR warm gas to be $\\sim 10^{-5}\\rm\\ M_{\\odot}$. ...

  7. The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison star

    CERN Document Server

    Jerzykiewicz, M; Daszynska-Daszkiewicz, J; Pigulski, A; Poretti, E; Rodriguez, E; Amado, P J; Kolaczkowski, Z; Uytterhoeven, K; Dorokhova, T N; Dorokhov, N I; Lorenz, D; Zsuffa, D; Kim, S -L; Bourge, P -O; Acke, B; De Ridder, J; Verhoelst, T; Drummond, R; Movchan, A I; Lee, J -A; Steslicki, M; Molenda-Zakowicz, J; Garrido, R; Kim, S -H; Michalska, G; Paparo, M; Antoci, V; Aerts, C

    2015-01-01

    A multisite photometric campaign for the Beta Cephei and eclipsing variable 16 Lacertae is reported. 749 h of high-quality differential photoelectric Stromgren, Johnson and Geneva time-series photometry were obtained with ten telescopes during 185 nights. After removing the pulsation contribution, an attempt was made to solve the resulting eclipse light curve by means of the computer program EBOP. Although a unique solution was not obtained, the range of solutions could be constrained by comparing computed positions of the secondary component in the Hertzsprung-Russell diagram with evolutionary tracks. For three high-amplitude pulsation modes, the uvy and the Geneva UBG amplitude ratios are derived and compared with the theoretical ones for spherical-harmonic degrees l <= 4. The highest degree, l = 4, is shown to be incompatible with the observations. One mode is found to be radial, one is l = 1, while in the remaining case l = 2 or 3. The present multisite observations are combined with the archival photo...

  8. Identification of gamma-ray emission from BZB J1450+5201: the most distant gamma-ray BL Lacertae object at z=2.47

    CERN Document Server

    Liao, N H; Liu, H T; Jiang, Ning; Yuan, Z L; Chen, Liang

    2013-01-01

    $\\gamma$-ray BL Lacertae objects (BL Lacs) with high redshifts ($z\\geq2$) are rarely detected. We report on an analysis of \\fermi data from five-year observation of 2FGL J1451.0+5159 whose $\\gamma$-ray emission is doubtful in the second \\fermi catalog (2FGL). It is detected at a higher energy, 3-10 GeV, with 6.7$\\sigma$ from our analysis than at 1-3 GeV from the 2FGL. The $\\gamma$-ray emission of the source is identified to be valid. Association presented in the 2FGL, between 2FGL J1451.0+5159 and BZB J1450+5201 whose redshift is suggested as 2.47, has been confirmed. BZB J1450+5201 appears to be the most distant $\\gamma$-ray BL Lac discovered to date. Multi-wavelength data from radio to $\\gamma$-ray energies are analyzed, indicating that this intermediate synchrotron peaked (ISP) source seems to be no difference from other ISP sources at lower redshifts in the second LAT AGN catalog. The pure SSC model is likely ruled out due to the extreme value of Doppler factor. Scattering of weak external emission plus S...

  9. Does diet in lacertid lizards reflect prey availability? Evidence for selective predation in the Aeolian wall lizard, Podarcis raffonei (Mertens, 1952 (Reptilia, Lacertidae

    Directory of Open Access Journals (Sweden)

    Pietro Lo Cascio

    2011-06-01

    Full Text Available In this paper the invertebrate fauna occurring on Scoglio Faraglione, a tiny Aeolian island (AeolianArchipelago, NE Sicily inhabited by a population of the critically endangered lacertid lizard Podarcis raffonei(Mertens, 1952, was censused at different seasons and the resulting data were then compared with dataobtained analysing prey composition and prey abundance in the diet of the lizards occurring on the same islet.The diet of Podarcis raffonei was mainly based on insects and other arthropods. The results indicate that dietcomposition is not directly influenced by prey availability and temporal prey abundance, and that there isstrong evidence indicating selective predation. Lizards prey upon a number of arthropod categories fewer thanthat recorded in field. Some invertebrate taxa (e.g. Diptera and Gastropoda are really less attractive for lizardsand are rarely preyed or not preyed at all despite their spatial and/or temporal abundance. This suggests thatPodarcis raffonei is able to operate a hierarchical choice within the range of prey items constituting its preyspectrum, probably through the ability to discriminate between prey chemicals or visually oriented predation.

  10. Does the conceptus of the viviparous lizard Barisia imbricata imbricata participates in the regulation of progesterone production and the control of luteolysis?

    Science.gov (United States)

    Martínez-Torres, Martín; Salcedo-Álvarez, Martha; Alvarez-Rodríguez, Carmen; Cárdenas-León, Mario; Luis, Juana; Moreno-Fierros, Leticia

    2014-08-01

    It is generally accepted that progesterone is necessary to maintain gestation; however, the mechanisms that control the production of this steroid remain unknown. The corpus luteum has been assigned a central role in the maintenance of gestation based on its capacity to produce progesterone. A pseudopregnancy model was performed in a viviparous lizard, Barisia imbricata imbricata, to determine whether the absence of embryos would affect the pattern of progesterone production or the corpus luteum histology. Blood samples were obtained prior to ovulation and at 8, 16, and 24 weeks after ovulation (pseudopregnant and pregnant lizards), as well as one day after parturition (pregnant lizards) or 32 weeks after ovulation (pseudopregnant lizards). The corpus luteum was surgically removed one day after blood samples were obtained. Blood aliquots from nongravid females were obtained at similar timepoints. We found a significant reduction in plasma progesterone concentrations at 24 and 32 weeks post-ovulation in pseudopregnant lizards compared with those observed at similar times in intact pregnant lizards, whereas the progesterone levels in non-gestant lizards remained significantly lower than in either pseudopregnant or pregnant lizards. Moreover, we observed that the histological appearance of the corpus luteum from pseudogestational females (obtained 24 and 32 weeks post-ovulation) differed from the corpora lutea from lizards in late gestation and intact parturient lizards. These observations suggest that the conceptus participates in the regulation of progesterone production in late gestation and also in luteolysis control.

  11. Formation mechanism of cracks in saturated sand

    Institute of Scientific and Technical Information of China (English)

    Xiaobing Lu; Zhemin Zheng; Yongren Wu

    2006-01-01

    The formation mechanism of "water film" (or crack) in saturated sand is analyzed theoretically and numerically.The theoretical analysis shows that there will be no stable "water film" in the saturated sand if the strength of the skeleton is zero and no positions are choked.It is shown by numerical simulation that stable water films initiate and grow if the choking state keeps unchanged once the fluid velocities decrease to zero in the liquefied sand column.The developments of "water film" based on the model presented in this paper are compared with experimental results.

  12. Lund Sand No 0:part 2

    OpenAIRE

    Ibsen, Lars Bo; Jakobsen, Finn Rosendal

    1996-01-01

    During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. T...

  13. Lund Sand No 0:part 1

    OpenAIRE

    Ibsen, Lars Bo; Jakobsen, Finn Rosendal

    1996-01-01

    During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. T...

  14. Biodegradable materials as foundry moulding sands binders

    Directory of Open Access Journals (Sweden)

    K. Major - Gabryś

    2015-07-01

    Full Text Available The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation.

  15. Acetaminophen and zinc phosphide for lethal management of invasive lizards Ctenosaura similis

    Institute of Scientific and Technical Information of China (English)

    Michael L. AVERY; John D. EISEMANN; Kandy L. KEACHER; Peter J. SAVARIE

    2011-01-01

    Reducing populations of invasive lizards through trapping and shooting is feasible in many cases but effective integrated management relies on a variety of tools,including toxicants.In Florida,using wild-caught non-native black spiny-tailed iguanas Ctenosaura similis,we screened acetaminophen and zinc phosphide to determine their suitability for effective population management of this prolific invasive species.Of the animals that received acetaminophen,none died except at the highest test dose,240 mg per lizard,which is not practical for field use.Zinc phosphide produced 100% mortality at dose levels as little as 25 mg per lizard,equivalent to about 0.5% in bait which is lower than currently used in commercial baits for eommensal rodent control.We conclude that zinc phosphide has potential as a useful tool for reducing populations of invasive lizards such as the black spiny-tailed iguana provided target-selective delivery methods are developed [Current Zoology 57 (5):625-629,2011].

  16. A body temperature model for lizards as estimated from the thermal environment

    NARCIS (Netherlands)

    Fei, T.; Skidmore, A.K.; Venus, V.; Wang, T.; Schlerf, M.; Toxopeus, A.G.; Overjijk, van S.; Bian, B.M.; Liu, Y.

    2012-01-01

    A physically based model was built to predict the transient body temperature of lizards in a thermally heterogeneous environment. Six heat transfer terms were taken into account in this model: solar radiation, convective heat flow, longwave radiation, conductive heat flow, metabolic heat gain and re

  17. 75 FR 77801 - Endangered and Threatened Wildlife and Plants; Endangered Status for Dunes Sagebrush Lizard

    Science.gov (United States)

    2010-12-14

    ... and Snell 1997, p. 1; Laurencio et al. 2007, p. 1; Chan et al. 2007, p. 337). In Texas, dunes... New Mexico, Sias and Snell (1998, p. 3) reported a negative relationship between oil well density and... sagebrush lizards declined by 50 percent when there were 29 pads per section (Sias and Snell 1998, p. 3...

  18. A body temperature model for lizards as estimated from the thermal environment

    NARCIS (Netherlands)

    Fei, T.; Skidmore, A.K.; Venus, V.; Wang, T.; Schlerf, M.; Toxopeus, A.G.; Overjijk, van S.; Bian, B.M.; Liu, Y.

    2012-01-01

    A physically based model was built to predict the transient body temperature of lizards in a thermally heterogeneous environment. Six heat transfer terms were taken into account in this model: solar radiation, convective heat flow, longwave radiation, conductive heat flow, metabolic heat gain and re

  19. Biogeographic history and cryptic diversity of saxicolous Tropiduridae lizards endemic to the semiarid Caatinga

    OpenAIRE

    Werneck, Fernanda P.; Leite, Rafael N; Silvia R Geurgas; Rodrigues, Miguel T

    2015-01-01

    Abstract Background Phylogeographic research has advanced in South America, with increasing efforts on taxa from the dry diagonal biomes. However, the diversification of endemic fauna from the semiarid Caatinga biome in northeastern Brazil is still poorly known. Here we targeted saxicolous lizards of the Tropidurus semitaeniatus species group to better understand the evolutionary history of these endemic taxa and the Caatinga. We estimat...

  20. Distinct Patterns of Desynchronized Limb Regression in Malagasy Scincine Lizards (Squamata, Scincidae)

    NARCIS (Netherlands)

    Miralles, A.; Hipsley, C.A.; Erens, J.; Gehara, M.; Rakotoarison, A.; Glaw, F.; Müller, J.; Vences, M.

    2015-01-01

    Scincine lizards in Madagascar form an endemic clade of about 60 species exhibiting a variety of ecomorphological adaptations. Several subclades have adapted to burrowing and convergently regressed their limbs and eyes, resulting in a variety of partial and completely limbless morphologies among ext