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1.
J Helminthol ; 94: e97, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31679527

RESUMO

Several factors influence the dynamics and structure of parasite communities. Our goal was to investigate how the community composition, prevalence and abundance of parasites change across seven populations of the exotic lizard Hemidactylus mabouia in Northeast Brazil, and to describe ontogenetic and sex variations. We found differences in the composition of component communities and patterns of infection according to the host body size across the lizard populations. We did not find any variation between the sexes regarding epidemiological patterns, which can probably be explained by the similar diet and habitat use of male and female H. mabouia. An unusually high abundance and prevalence of trematodes infecting this host lizard was apparent when we compared other native lizard hosts, and we suggest that local environmental conditions might be advantageous to the development and life cycle of these parasites due to the abundance of all the intermediate and definitive hosts.


Assuntos
Lagartos/parasitologia , Parasitos/isolamento & purificação , Doenças Parasitárias em Animais/parasitologia , Animais , Tamanho Corporal , Brasil/epidemiologia , Ecossistema , Feminino , Lagartos/classificação , Lagartos/crescimento & desenvolvimento , Masculino , Parasitos/classificação , Parasitos/genética , Parasitos/fisiologia , Doenças Parasitárias em Animais/epidemiologia
2.
Environ Pollut ; 255(Pt 2): 113297, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31610514

RESUMO

Prothioconazole (PTC) is a widely used triazole fungicide with low toxicity, and its desulfurization metabolite, prothioconazole-desthio (PTC-d), is reported to have higher reproductive toxicity to mammals. However, little is known about the reproductive toxicity, much less endocrine disrupting effect, of these two chemicals on reptiles. In this study, we investigated the effects of single dose of PTC/PTC-d (100 mg kg-1 body weight) exposure on the pathomorphism of testes and epididymides, serum sex steroid hormones (testosterone and 17ß-estradiol) and transcription of steroidogenic-related genes (STARD, cyp11A, cyp17, cyp19A, 17ß-HSD, 3ß-HSD, AR and ER-α) in gonads of male lizards (Eremias argus). Although structural disorder existed in PTC-d exposure group, severe gonadal disruption, especially suppression of spermatogenesis was only observed in testis after PTC treatment, which consequently led to the lack of spermatozoa in epididymal ducts. Consistent with this result, T/E2 value in PTC exposure was elevated to a significant higher level compared with control and continually increased over time, while T/E2 value in the PTC-d exposure group slightly increased only at 12 h. These results demonstrated a more serious disruption of PTC on male lizard gonads than PTC-d. In addition, the expression of cyp17 gene was inhibited at 6 h, however, was induced at 12 h, and exhibited negative correlations with STARD, cyp11A and 3ß-HSD after PTC exposure at each timepoint. In PTC-d group, the expression of STARD and 3ß-HSD were significantly down-regulated, in contrast, cyp11A and cyp17 were up-regulated, and each gene showed consistent changes over time. For 17ß-HSD, no significance was observed in both treated groups. This study was the first to compare the gonadal disruption of PTC and PTC-d in male lizards and elucidated that these two chemicals influenced the physiological function of male gonads through differential transcriptional modulation.


Assuntos
Disruptores Endócrinos/toxicidade , Fungicidas Industriais/toxicidade , Lagartos/crescimento & desenvolvimento , Testículo/efeitos dos fármacos , Triazóis/toxicidade , Administração Oral , Animais , Estradiol/sangue , Lagartos/sangue , Masculino , Reprodução/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Testículo/patologia , Testosterona/sangue
3.
PLoS One ; 14(7): e0219053, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291313

RESUMO

Male genitalia show considerable morphological variation among animals with internal fertilization and exhibit a high level of evolvability in lizards. Studies have suggested that sexual selection may be driving hemipenial evolution against natural selection and pleiotropy. Given the direct interaction of male and female genitals, coevolution of the aforementioned is posited by several hypotheses of genital evolution. However, there are only a few studies on female genitalia morphology, resulting in a lack of coevolution description and understanding. Studies of allometric patterns have filled some gaps by answering questions about male genital evolution and could prove a powerful tool in clarifying coevolution between male and female genitals. Here, we studied the genital morphology of Tropidurus torquatus. This Tropidurus lizard species is an emerging Neotropical lizard model organism notable for having enlarged hemipenial lobes in contrast with other tropidurid species. In this study, we analyzed hemipenial development in early and late stages, describing both morphological variation and ontogenetic allometric pattern. We used quantitative traits to describe male and female genital morphology, examining their static allometric patterns and correspondence. Our study provides a quantitative discussion on the evolution of lizard genitals, suggesting that sexual selection plays an important role in genital evolution in Tropidurus lizards.


Assuntos
Genitália Feminina/anatomia & histologia , Genitália Masculina/anatomia & histologia , Lagartos/crescimento & desenvolvimento , Animais , Evolução Biológica , Feminino , Genitália Feminina/crescimento & desenvolvimento , Genitália Masculina/crescimento & desenvolvimento , Lagartos/anatomia & histologia , Masculino , Filogenia , Seleção Genética , Comportamento Sexual
4.
Behav Processes ; 165: 9-13, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31170461

RESUMO

After laying their eggs, oviparous reptiles are reliant on the external environment to provide the required incubation conditions for successful embryonic development. Egg incubation temperature can impact the behaviour of various species of reptiles, but previous experiments have focused on the impact of incubation environment on hatchlings, with only a limited number of studies focussing on the longer-term behavioural consequences of incubation environment. This study investigated the effects of developmental environment on bearded dragon lizards (Pogona vitticeps) that were incubated at different temperatures within the natural range; half of them were incubated at a 'hot' temperature (30 ±â€¯3 °C) and half at a 'cold' temperature (27 ±â€¯3 °C). The growth and foraging behaviour of the lizards was then compared over 18 weeks of development. Although the lizards incubated at a cool temperatures grew more quickly, those incubated at the hotter temperature completed the foraging task more often and had significantly faster running speeds. These results show that egg incubation temperature impacts the foraging behaviour of juvenile lizards and suggest a potential trade-off between growth and foraging speed, which could influence an animal's life history trajectory.


Assuntos
Comportamento Apetitivo/fisiologia , Lagartos/crescimento & desenvolvimento , Óvulo/crescimento & desenvolvimento , Temperatura , Animais , Feminino , Corrida
5.
Elife ; 82019 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-31234966

RESUMO

The spectacular frill around the neck of the lizard Chlamydosaurus has its origins in a mechanical instability that arises during development.


Assuntos
Lagartos/crescimento & desenvolvimento , Fenômenos Mecânicos , Modelos Teóricos , Morfogênese/genética , Animais , Humanos , Lagartos/genética , Modelos Biológicos , Pescoço/fisiologia
6.
PLoS Comput Biol ; 15(4): e1006943, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31009449

RESUMO

Genotypic variation, environmental variation, and their interaction may produce variation in the developmental process and cause phenotypic differences among individuals. Developmental noise, which arises during development from stochasticity in cellular and molecular processes when genotype and environment are fixed, also contributes to phenotypic variation. While evolutionary biology has long focused on teasing apart the relative contribution of genes and environment to phenotypic variation, our understanding of the role of developmental noise has lagged due to technical difficulties in directly measuring the contribution of developmental noise. The influence of developmental noise is likely underestimated in studies of phenotypic variation due to intrinsic mechanisms within organisms that stabilize phenotypes and decrease variation. Since we are just beginning to appreciate the extent to which phenotypic variation due to stochasticity is potentially adaptive, the contribution of developmental noise to phenotypic variation must be separated and measured to fully understand its role in evolution. Here, we show that variation in the component of the developmental process corresponding to environmental and genetic factors (here treated together as a unit called the LALI-type) versus the contribution of developmental noise, can be distinguished for leopard gecko (Eublepharis macularius) head color patterns using mathematical simulations that model the role of random variation (corresponding to developmental noise) in patterning. Specifically, we modified the parameters of simulations corresponding to variation in the LALI-type to generate the full range of phenotypic variation in color pattern seen on the heads of eight leopard geckos. We observed that over the range of these parameters, variation in color pattern due to LALI-type variation exceeds that due to developmental noise in the studied gecko cohort. However, the effect of developmental noise on patterning is also substantial. Our approach addresses one of the major goals of evolutionary biology: to quantify the role of stochasticity in shaping phenotypic variation.


Assuntos
Evolução Biológica , Biologia Computacional/métodos , Genótipo , Fenótipo , Animais , Padronização Corporal/fisiologia , Lagartos/crescimento & desenvolvimento , Lagartos/fisiologia , Pigmentação da Pele/fisiologia
7.
Proc Natl Acad Sci U S A ; 116(9): 3646-3655, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808754

RESUMO

Viviparous (live-bearing) vertebrates have evolved repeatedly within otherwise oviparous (egg-laying) clades. Over two-thirds of these changes in vertebrate reproductive parity mode happened in squamate reptiles, where the transition has happened between 98 and 129 times. The transition from oviparity to viviparity requires numerous physiological, morphological, and immunological changes to the female reproductive tract, including eggshell reduction, delayed oviposition, placental development for supply of water and nutrition to the embryo by the mother, enhanced gas exchange, and suppression of maternal immune rejection of the embryo. We performed genomic and transcriptomic analyses of a closely related oviparous-viviparous pair of lizards (Phrynocephalus przewalskii and Phrynocephalus vlangalii) to examine these transitions. Expression patterns of maternal oviduct through reproductive development of the egg and embryo differ markedly between the two species. We found changes in expression patterns of appropriate genes that account for each of the major aspects of the oviparity to viviparity transition. In addition, we compared the gene sequences in transcriptomes of four oviparous-viviparous pairs of lizards in different genera (Phrynocephalus, Eremias, Scincella, and Sphenomorphus) to look for possible gene convergence at the sequence level. We discovered low levels of convergence in both amino acid replacement and evolutionary rate shift. This suggests that most of the changes that produce the oviparity-viviparity transition are changes in gene expression, so occasional reversals to oviparity from viviparity may not be as difficult to achieve as has been previously suggested.


Assuntos
Evolução Molecular , Oviparidade/genética , Transcriptoma/genética , Viviparidade não Mamífera/genética , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Genômica , Lagartos/genética , Lagartos/crescimento & desenvolvimento , Filogenia , Placentação/genética , Gravidez , Reprodução/genética , Serpentes/genética , Serpentes/crescimento & desenvolvimento
8.
J Agric Food Chem ; 67(8): 2183-2189, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30721048

RESUMO

In this study, the different metabolic pathways of lambda-cyhalothrin (LCT) enantiomers in Eremias argus feces and enantioselective disruption on hypothalamus-pituitary-gonad (HPG) system were investigated. After 7 days oral exposure to LCT enantiomers, the concentration of 3-phenoxybenzoic acid (PBA), hydroxylated and sulfated LCT were higher in the (+)-LCT exposure group than that in the (-)-LCT exposure group, which indicated a higher metabolic rate of (+)-LCT than (-)-LCT. Although no significant differences were seen on lizard body weight after enantiomers' exposure, the gonadosomatic index was dramatically decreased. The testicular impacts such as increased seminiferous tubule diameters were only observed in the (+)-LCT exposure group. Consistent with this result, the expression of ar gene in the (+)-LCT exposure was significantly higher than that in the (-)-LCT exposure group. In addition, the stronger binding affinity of AR with (+)-LCT further demonstrated the more serious disruption of (+)-LCT on lizard HPG axis than (-)-LCT. This study first elucidated the metabolic pathway and endocrine effects of LCT in lizards at enantiomeric level and provided some evidence for lizard population decline.


Assuntos
Disruptores Endócrinos/química , Inseticidas/química , Lagartos/crescimento & desenvolvimento , Nitrilos/química , Piretrinas/química , Testículo/crescimento & desenvolvimento , Animais , Disruptores Endócrinos/metabolismo , Inseticidas/metabolismo , Lagartos/metabolismo , Masculino , Nitrilos/metabolismo , Piretrinas/metabolismo , Estereoisomerismo
9.
Sci Total Environ ; 662: 834-841, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-30795479

RESUMO

The potential endocrine disruption of neonicotinoids poses a significant threat to the survival of small farmland lizards. We systematically evaluated the distribution, metabolism, and toxicity of three neonicotinoids (dinotefuran, thiamethoxam, and imidacloprid) in the Eremias argus during a 35-day oral administration exposure. Lizards could quickly transfer and store neonicotinoids into the scale and eliminated through molting. Dinotefuran was most prone to accumulation in lizard tissues, followed by thiamethoxam, and imidacloprid was generally present in the form of its terminal metabolite 6-chloropyridinyl acid. Exposure to dinotefuran resulted in hepatic oxidative stress damage, decreased plasma growth hormone concentration, and down-regulation of ghr, igf1 and igfbp2 gene expression. These indicated that dinotefuran might have potential growth inhibition toxicity to lizards. Although imidacloprid caused severe liver oxidative stress damage, the effect of imidacloprid on GH/IGF axis was not obvious. Compared to dinotefuran and imidacloprid, thiamethoxam had the least damage to liver and minimal impact on GH/IGF axis. This study verified the possible damage of neonicotinoids to lizard liver and the interference of GH/IGF axis for the first time.


Assuntos
Poluentes Ambientais/toxicidade , Inseticidas/toxicidade , Fígado/efeitos dos fármacos , Lagartos/metabolismo , Neonicotinoides/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Animais , China , Poluentes Ambientais/farmacocinética , Fazendas , Feminino , Expressão Gênica/efeitos dos fármacos , Hormônio do Crescimento/genética , Hormônio do Crescimento/metabolismo , Inseticidas/farmacocinética , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Fígado/metabolismo , Fígado/patologia , Lagartos/genética , Lagartos/crescimento & desenvolvimento , Masculino , Modelos Teóricos , Neonicotinoides/farmacocinética , Distribuição Tecidual
10.
Artigo em Inglês | MEDLINE | ID: mdl-30240787

RESUMO

Oviparous reptile embryos must tolerate fluctuations in oxygen availability and incubation temperature during development. In this study, regional hypoxia was simulated by painting eggs of Eublepharis macularius with melted paraffin wax to decrease the available surface area for gas exchange by approximately 80%. Experimental and control eggs were incubated at either 28 or 34 °C and embryo mass, stage, heart mass, relative heart mass, and oxygen consumption (V̇O2) were measured at 15 and 30 days of incubation. Embryo mass from the regional hypoxia treatment was reduced by about 50% at day 15 and by about 30% at day 30 of incubation, independent of incubation temperature compared to controls. Embryo stage from the regional hypoxia treatment was reduced by about 2 stages at day 15 independent of incubation temperature but there was no effect of hypoxia treatment at day 30. Absolute heart mass was reduced by about 60% in regional hypoxia embryos sampled at day 15 while relative heart mass was increased by about 30% in regional hypoxic embryos at day 30 compared to controls, suggesting that heart mass is conserved at the expense of somatic growth. Embryo V̇O2 was affected by incubation temperature at both 15 and 30 days of incubation but not by regional hypoxia treatment. These results indicate that embryos of E. macularius possess plasticity in their capacity to respond to reduction in oxygen availability during incubation, and are able to survive and continue developing when gas exchange surface area is severely limited.


Assuntos
Embrião não Mamífero/metabolismo , Coração/embriologia , Hipóxia/patologia , Lagartos/embriologia , Consumo de Oxigênio , Temperatura , Animais , Feminino , Hipóxia/metabolismo , Lagartos/crescimento & desenvolvimento , Lagartos/metabolismo , Masculino , Oxigênio/metabolismo
11.
Ecotoxicol Environ Saf ; 169: 61-67, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30419507

RESUMO

Several geographical areas where Salvator merianae is distributed in Argentina are included in regions with agricultural activity and exposed to pesticide formulations. Some pesticides could affect defense mechanisms being able alter structures of some components of immune and endocrine systems. To assess the potential effects of pesticides in this reptile under seminatural conditions, on the immune system and endocrine responses in S. merianae we analyzed several blood parameters. Total (TWBCC), differential (DWBCC) white blood cells count, heterophils/lymphocytes index (H/L), lobularity index (LI), natural antibodies (NAbs) titres, complement system (CS), and corticosterone concentration were analyzed in animals exposed to a mixture of cypermethrin (25%), glyphosate (66.2%) and chlorpyrifos (48%) formulations. In addition, body size was considered in these analyzes. TWBCC and NAbs revealed lower values in organisms exposed to pesticides respect to a control indicating a possible immunosuppression effect. Besides, the LI showed a greater number of lobes in organism exposed demonstrating symptoms of chronic infection. In addition, we observed a reduced growth in these animals possibly related to a less energy investment in body mass to maintain an active defense against pesticides. Finally, we found high levels of plasma corticosterone in animals exposed to mix formulation that could demonstrate neuroendocrine axis activation. Other parameters like DWBCC, H/L index and activity of CS showed no differences in treated animals respect to control group, which could indicate low sensibility of these parameters to the concentration of pesticides used. Our results provide evidence of the toxic effects of pesticides on different immune system parameters, but also a trade-off among these parameters, corticosterone levels and growth. In this way, we can conclude that the formulated pesticides applied widely and constantly in the areas occupied by S. merianae, would be affecting its immune and endocrine systems and therefore its ability to defend against external agents. This kind of studies is of great interest to know the possible responses of wild species to anthropogenic disturbances such as pesticide contamination.


Assuntos
Lagartos , Animais , Clorpirifos/toxicidade , Corticosterona/sangue , Sistema Endócrino/efeitos dos fármacos , Glicina/análogos & derivados , Glicina/toxicidade , Sistema Imunitário/efeitos dos fármacos , Lagartos/sangue , Lagartos/crescimento & desenvolvimento , Lagartos/imunologia , Praguicidas/toxicidade , Piretrinas/toxicidade
12.
J Therm Biol ; 78: 263-269, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30509645

RESUMO

Temperature has a substantial effect on both the physiology and behavior of ectothermic animals such as lizards. Physiology and behavior can also be influenced by ontogenetic and sex differences, but these effects are largely understudied in lizards. We examined ontogenetic and sex-based differences in thermal tolerances, preferred temperature, and temperature-dependent evaporative water loss rates in Italian Wall Lizards, Podarcis siculus, collected from an introduced population near Los Angeles, California, USA that were acclimated to laboratory conditions. Podarcis siculus has been introduced to multiple localities in the USA and the Mediterranean region and has demonstrated remarkable ability to adapt to novel climatic conditions. In the California population, adults of both sexes had a higher critical thermal maximum (CTmax) than juveniles, and adult females had a lower critical thermal minimum (CTmin) than juveniles and adult males. Thus, adult females had a significantly wider thermal breadth (CTmax - CTmin) compared to adult males and juveniles. Mass-specific evaporative water loss was higher in juveniles compared to adult males at intermediate temperatures. There was no significant difference among groups for preferred temperature. This implies that thermal tolerance, a physiological characteristic, varies with age and sex for this population, whereas thermal preference, a behavioral characteristic, does not. Interestingly, CTmin for all age and sex classes was above temperatures likely experienced by some nonnative populations in winter, suggesting individuals need to find urban thermal retreats. These results add to the growing literature demonstrating that thermal tolerances and breadths can vary between sexes and across age classes in squamate species.


Assuntos
Espécies Introduzidas , Lagartos/fisiologia , Termotolerância , Animais , Variação Biológica da População , Feminino , Lagartos/crescimento & desenvolvimento , Masculino
13.
Sci Rep ; 8(1): 14892, 2018 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-30291276

RESUMO

Vertebrate sex differentiation follows a conserved suite of developmental events: the bipotential gonads differentiate and shortly thereafter sex specific traits become dimorphic. However, this may not apply to squamates, a diverse vertebrate lineage comprising of many species with thermosensitive sexual development. Of the three species with data on the relative timing of gonad differentiation and genital dimorphism, the females of two (Niveoscincus ocellatus and Barisia imbricata) exhibit a phase of temporary pseudohermaphroditism or TPH (gonads have differentiated well before genital dimorphism). We report a third example of TPH in Pogona vitticeps, an agamid with temperature-induced male to female sex reversal. These findings suggest that for female squamates, genital and gonad development may not be closely synchronised, so that TPH may be common. We further observed a high frequency of ovotestes, a usually rare gonadal phenotype characterised by a mix of male and female structures, exclusively associated with temperature-induced sex reversal. We propose that ovotestes are evidence of a period of antagonism between male and female sex-determining pathways during sex reversal. Female sexual development in squamates is considerably more complex than has been appreciated, providing numerous avenues for future exploration of the genetic and hormonal cues that govern sexual development.


Assuntos
Lagartos/crescimento & desenvolvimento , Animais , Feminino , Gônadas/crescimento & desenvolvimento , Gônadas/ultraestrutura , Masculino , Processos de Determinação Sexual , Diferenciação Sexual , Temperatura
14.
Zoology (Jena) ; 129: 45-53, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30170747

RESUMO

Ontogenetic shifts from an insectivorous diet towards an herbivorous one are well known in lizards. Energetic, behavioral and morphological factors have been linked to this pattern, but the latter have received less attention, especially with respect to head morphology. It is known that robust heads are related to stronger bite forces, consequently facilitating the consumption of harder or tougher, more fibrous items such as plants. In this study the ontogeny of diet and head morphology of the omnivorous tropidurid lizard Microlophus thoracicus are described. We found a significant ontogenetic shift from a mainly insectivorous diet in juveniles to a mainly herbivorous one in adults. In parallel, we measured the length, height and width of the head of the studied individuals. We found that adult individuals showed proportionally taller and wider heads when compared to juveniles, and that these increases in proportional head dimensions were significantly correlated with the increase in plant material in the diet that we observed. Additionally, we compared the morphologies of adults and juveniles of M. thoracicus and two other Microlophus species known to be insectivorous. These comparisons showed that M. thoracicus adults have proportionally more robust heads when compared to their insectivorous congeners, which is in agreement with the hypothesized link between head morphology and diet characteristics. The results of this study suggest that the known relationship between herbivory and head morphology is maintained even in an ontogenetic context, but further study is needed to determine the effect of other selective pressures which influence these changes in morphology.


Assuntos
Dieta/veterinária , Cabeça/anatomia & histologia , Lagartos/crescimento & desenvolvimento , Envelhecimento , Animais , Tamanho Corporal , Comportamento Alimentar , Herbivoria , Insetos , Lagartos/anatomia & histologia , Comportamento Predatório , Especificidade da Espécie
15.
BMC Ecol ; 18(1): 37, 2018 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-30249235

RESUMO

BACKGROUND: Ectothermic animals living in cold (high latitude or high elevation) regions are predicted to grow slower due to limited thermal opportunities for activity and food resources than those living in warm regions. However, the Qinghai toad-headed lizards (Phrynocephalus vlangalii) grow faster and reach a larger adult size at a high-elevation site than at a low-elevation site. In this study, we aimed to identify the genetic and environmental causes of this between-population difference in growth rate by conducting mark-recapture and common garden experiments on juvenile growth rate, and investigating the thermal environment, lizard body temperature, potential prey availability at the two elevation sites. RESULTS: Compared with low-elevation individuals, high-elevation juvenile lizards had higher growth rates in the field, but grew at similar rates in the laboratory. High-elevation lizards had higher active body temperatures than low-elevation lizards despite similar air temperatures in the period of field investigation. The high-elevation site had relatively more and larger preys than the low-elevation site. CONCLUSIONS: Inter-population difference in growth rate of P. vlangalii may primarily result from developmental plasticity in response to the difference in environmental resources, rather than genetic differentiation. The higher growth rate of high-elevation lizards is likely associated with higher potential food availability and higher active body temperatures.


Assuntos
Altitude , Temperatura Corporal , Dieta , Lagartos/crescimento & desenvolvimento , Animais , China , Temperatura Baixa
16.
J Exp Zool A Ecol Integr Physiol ; 329(10): 527-535, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30096219

RESUMO

Habitat selection models can explain spatial patterns in the relative abundance of animals in different habitats based on the assumption that fitness declines as density in a habitat increases. Ectotherms, such as lizards, may not follow predictions of density-dependent habitat selection models because temperature, which is unaffected by density, strongly influences their habitat selection. If competition for limited resources decreases fitness, then crowding should cause a decrease in body size and growth rates. We used skeletochronology and body size data from tree lizards (Urosaurus ornatus) at six sites that each spanned two habitats varying in quality to test the hypothesis that habitat selection is density dependent because growth is limited by competition for resources and by habitat quality. First, we tested that the maximum body size of lizards decreased with higher densities in a habitat by comparing growth between sites. Second, we tested whether body size and growth were higher in the habitat with more resources by controlling for density in a habitat and comparing growth between habitats in different sites. We found evidence of density-dependent growth in females, but not in males. Females in more crowded sites reached a smaller maximum size. Females in the higher quality habitat also grew larger than females in the lower quality habitat after controlling for differences in density between the habitats. Therefore, we found partial support for our hypothesis that competition for resources limits growth and causes density-dependent habitat selection.


Assuntos
Ecossistema , Lagartos/crescimento & desenvolvimento , Animais , Arizona , Tamanho Corporal , Desenvolvimento Ósseo , Densidade Demográfica
17.
J Exp Zool A Ecol Integr Physiol ; 329(6-7): 308-316, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29938929

RESUMO

Developmental plasticity creates marked variation in individual phenotypes when the environment is patchy, such as when the thermal environment varies. Plasticity may occur in response to the environment experienced during an individual's lifetime or to the environment experienced by parents (transgenerational plasticity), and may be adaptive if it enhances fitness. In particular, plasticity in thermal traits, such as preferred temperatures and thermal limits, may improve performance and fitness based on temperatures in the local environment. This study examined the influence of parental and offspring thermal environments (duration of access to a basking lamp) on offspring thermal traits (preferred temperatures and panting threshold) in jacky dragons (Agamidae: Amphibolurus muricatus). Long-bask parental environments led, indirectly, to higher preferred temperatures of offspring due to increased offspring body mass compared to offspring of short-bask parents. The increase in median temperature preference was associated with a higher voluntary minimum body temperature and a narrower preference range, suggesting tradeoffs in thermal behavior and a matching of offspring preferences to the parental environment. Parental thermal treatment did not influence offspring panting threshold. Instead, the panting threshold tended to be higher in offspring that were reared in the long-bask treatment compared to those in the short-bask treatment, suggesting longer basking environments increased thermal tolerance. Parental and offspring thermal environment did not exhibit any interactive effect on thermal traits. The results indicate that thermal environments experienced by lizards can have both transgenerational and within-generation impacts on thermal traits, thus influencing how populations respond to fluctuating or changing climates.


Assuntos
Lagartos/crescimento & desenvolvimento , Lagartos/fisiologia , Temperatura , Adaptação Fisiológica , Animais , Regulação da Temperatura Corporal/fisiologia , Feminino , Masculino , Pais , Respiração
18.
J Morphol ; 279(8): 1088-1103, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29732599

RESUMO

Postnatal growth patterns within the vertebral column may be informative about body proportions and regionalization. We measured femur length, lengths of all pre-sacral vertebrae, and lengths of intervertebral spaces, from radiographs of a series of 21 Eublepharis macularius, raised under standard conditions and covering most of the ontogenetic body size range. Vertebrae were grouped into cervical, sternal, and dorsal compartments, and lengths of adjacent pairs of vertebrae were summed before analysis. Femur length was included as an index of body size. Principal component analysis of the variance-covariance matrix of these data was used to investigate scaling among them. PC1 explained 94.19% of total variance, interpreted as the variance due to body size. PC1 differed significantly from the hypothetical isometric vector, indicating overall allometry. The atlas and axis vertebrae displayed strong negative allometry; the remainder of the vertebral pairs exhibited weak negative allometry, isometry or positive allometry. PC1 explained a markedly smaller amount of variance for the vertebral pairs of the cervical compartment than for the remainder of the vertebral pairs, with the exception of the final pair. The relative standard deviations of the eigenvalues from the PCAs of the three vertebral compartments indicated that the vertebrae of the cervical compartment were less strongly integrated by scaling than were the sternal or dorsal vertebrae, which did not differ greatly between themselves in their strong integration, suggesting that the growth of the cervical vertebrae is constrained by the mechanical requirements of the head. Regionalization of the remainder of the vertebral column is less clearly defined but may be associated with wave form propagation incident upon locomotion, and by locomotory changes occasioned by tail autotomy and regeneration. Femur length exhibits negative allometry relative to individual vertebral pairs and to vertebral column length, suggesting a change in locomotor requirements over the ontogenetic size range.


Assuntos
Lagartos/crescimento & desenvolvimento , Sacro/crescimento & desenvolvimento , Coluna Vertebral/crescimento & desenvolvimento , Animais , Tamanho Corporal , Fêmur/anatomia & histologia , Lagartos/anatomia & histologia , Locomoção , Análise de Componente Principal , Coluna Vertebral/anatomia & histologia
19.
Proc Biol Sci ; 285(1879)2018 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-29794051

RESUMO

The timing of reproductive events (e.g. oviposition and hatching) to coincide with favourable seasonal conditions is critical for successful reproduction. However, developmental time may not match the duration between the optimal time for oviposition and the optimal time for hatchling survival. Thus, strategies that alter the time between oviposition and hatchling emergence can be highly advantageous. Arrested development and the resulting extension of the duration between oviposition and hatching has been widely documented across oviparous amniotes, but nest overwintering by hatchlings has only been documented in aquatic chelonians that live where winters are quite cold. Herein, we present a compilation of evidence regarding reproductive phenology by hatchlings of the Gila monster (Heloderma suspectum), a lizard inhabiting the Sonoran Desert of North America. Our data demonstrate that (i) Gila monster hatchlings from eggs oviposited in July do not emerge from their nests until late spring or summer of the following year, yet (ii) Gila monster eggs artificially incubated at field-relevant temperatures hatch in 4-5 months. Furthermore, we describe a fortuitous excavation of a hatching Gila monster nest in late October, which coincides with the artificial incubation results. Together, these results provide strong support for the existence of overwintering in the nest by a lizard, and suggest that this reproductive strategy should be explored in a broader array of taxa.


Assuntos
Lagartos/fisiologia , Comportamento de Nidação , Animais , Arizona , Feminino , Lagartos/crescimento & desenvolvimento , Reprodução , Estações do Ano
20.
J Exp Zool A Ecol Integr Physiol ; 329(6-7): 298-307, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29682910

RESUMO

Embryonic environments affect a range of phenotypic traits including sex and reproductive success. I determined (1) how the interaction between incubation temperature and egg size affects sex allocation of Chamaeleo calyptratus and (2) how incubation temperature and maternal parent (clutch) affect water uptake by eggs and body size, growth, and climbing speed of hatchlings and juveniles. Eggs from five clutches were exposed to five temperature treatments with clutches replicated within and among treatments. Temperature affected sex, but only when egg size was included as a factor in analyses. At intermediate (28°C) temperatures, daughters were more likely to be produced from large eggs and sons more likely to be produced from small eggs, while at 25 and 30°C, the pattern of sex allocation was reversed. Temperature and clutch affected water uptake and body size. Nonetheless, the direction of temperature and clutch effects on water uptake by eggs and on the size of hatchlings were not the same and the direction of temperature effects on body sizes of hatchlings and juveniles differed as well. Clutch affected hatchling size but not juvenile size and growth rate. Clutch, but not incubation temperature, affected climbing speed, but the fastest hatchlings were not from the same clutches as the fastest juveniles. The independent effects of incubation temperature and clutch indicate that hatchling phenotypes are influenced largely by conditions experienced during incubation, while juvenile phenotypes are influenced largely by conditions experienced in the rearing environment.


Assuntos
Lagartos/embriologia , Óvulo , Processos de Determinação Sexual/fisiologia , Temperatura , Animais , Animais Recém-Nascidos , Tamanho Corporal , Embrião não Mamífero/embriologia , Feminino , Lagartos/crescimento & desenvolvimento , Lagartos/fisiologia , Locomoção , Masculino , Fenótipo , Água/metabolismo
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