RESUMO
Incubation temperature is among the main phenotypic trait variation drivers studied since the developmental trajectory of oviparous animals is directly affected by environmental conditions. In the last decades, global warming predictions have aroused interest in understanding its impacts on biodiversity. It is predicted that the effects of direct warming will be exacerbated by other anthropogenic factors, such as microclimatic edge effects. Although the Brazilian Cerrado biome is one of the most affected by these issues, little is known about the aforementioned effects on its biodiversity. Therefore, the aim of our study is to investigate the influence of incubation temperature on developmental parameters, morphology and thermal physiology traits of the collared lizard (Tropidurus torquatus). Furthermore, we discuss our findings regarding lizard developmental biology and the climate change paradigm. Therefore, we incubated T. torquatus eggs under five temperature regimes ranging from artificial nest temperature (28.7 °C) to 35.0 °C. We found that elevated incubation temperatures affect several investigated traits: egg mass gain is positively affected, without any influence in newborn mass; incubation period is broadly reduced with temperature increase; survival rate is negatively affected by temperature, constant 35.0 °C regime is confirmed as a lethal incubation temperature, and the sex ratio is affected at 30.0 °C, with a prevailing outbreak of females. Increased incubation temperature also affects body and head size but has no effect on limb size. Newborn thermoregulation and the critical thermal maximum (CTmax) are not affected by incubation temperature. On the other hand, basal body temperature (Tbb) and the critical thermal minimum (CTmin) were positively affected. Thermal physiology was also affected by age, with newborns differing from adults for all analyzed thermal traits. Our findings indicate that future modifications in incubation temperature regimes at nesting sites caused by warming may affect several features of the development, morphology, and thermal physiology of newborns of this species. Laboratory experiments have pointed to possible drastic effects of warming on lizard survival rates, also affecting aspects of its natural history and population distribution. Moreover, in addition to being more vulnerable than adults in aspects such as predation and feeding, T. torquatus newborns are also more vulnerable regarding thermal physiological traits.
Assuntos
Lagartos , Animais , Mudança Climática , Ecossistema , Feminino , Aquecimento Global , Lagartos/fisiologia , TemperaturaRESUMO
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.