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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 (CT max ) are not affected by incubation temperature. On the other hand, basal body temperature (T bb ) and the critical thermal minimum (CT min ) 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.

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.

While much attention has been paid to vector-borne filariasis, diseases that threaten millions of people in tropical and subtropical countries, the literature on host–parasite associations and transmission strategies of filarial nematodes in wildlife is scarce. Here, we report the co-occurrence of chigger mites (Eutrombicula alfreddugesi) and onchocercid nematodes (Oswaldofilaria chabaudi) parasitizing the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Examination of chiggers established, for the first time, the occurrence of microfilariae in trombiculid mites (Trombiculidae). These larvae were morphologically similar to those recovered from adult females of O. chabaudi. The current evidence suggests that chiggers do not play a role in the transmission of filarioid nematodes, but rather act as accidental or dead-end hosts. Nevertheless, considering the polyphagous nature of trombiculid mites, similar to blood-sucking insects involved in the transmission of several infectious diseases, further studies may shed light on the potential role of chiggers as vectors of filarioids.

Urbanization is responsible for numerous environmental changes including pollution. Information on the susceptibility of reptiles to environmental contaminants is relatively scarce. Tropidurus torquatus represents a potential bioindicator of heavy metal pollution. Levels of heavy metals in tissues from T. torquatus depend on bioavailability and vary among different populations. The aim of this study was to determine the heavy metal concentration in liver and fat tissue of T. torquatus from three distinct populations in the state of Espírito Santo, Brazil. The study areas included coastal rocky outcrops, dunes, and mountain rocky outcrops; each area had a different climate, vegetation, and level of anthropogenic influence. Fifty-one individuals were captured. Biometrics and sexes were determined, and stomach contents were identified. The tissue samples were digested with nitric acid and analyzed via inductively coupled plasma optical emission spectrometry (ICP-OES) for aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), strontium (Sr), titanium (Ti), vanadium (V), and zinc (Zn) contents. The concentration of zinc in Tropidurus torquatus was higher in liver than in fat tissue (432 ± 1380 mg kg−1), and that of aluminum was higher in fat tissue (765 ± 1455 mg.kg−1). The animals’ diet may be related to heavy metal contamination. The study suggests that T. torquatus could be used for soil biomonitoring with liver as a bioindicator for aluminum contamination and fat tissue as a bioindicator for zinc contamination.

The objective of the present study was to learn which species of Squamata reptiles occur in Protected Area Säo José, in Tiradentes, Minas Gerais, Brazil. Between November 2009 and December 2010 reptiles were captured. In total 157 specimens were recorded of 29 species, 16 snakes, 12 lizards and one amphisbaena. Among the snakes, Dipsadidae showed the greatest richness, with a total of nine species. The group of snakes had the highest number of species present in the community, but 79% of sampled specimens were lizards, Enyalius bilineatus being the most abundant species, with 21% of occurrence. The area with the highest richness was the Cerradäo. The lower abundance was found in the Gallery Forest area (n=14), but it was the vegetation type with the highest equitability. Areas of Cerradäo and Cerrado sensu strictu showed the most similarity. In these areas five species were recorded in common, Bothrops neuwiedi (n=3) being the only species of snake, and the two species of lizards most abundant in both environments were Enyalius bilineatus (n=32) and Ameivula ocellifera (n=19). Ophiodes striatus and Xenodon merremii were common to Cerradäo and Dirty Field areas. There was no species recorded that were common to the environments of Cerrado and Dirty Field but two species not sympatric were found of the same genus, Tropidurus torquatus, which was found only in the Cerrado sensu strictu and Tropidurus itambere exclusively in Dirty Field. Since none of the rarefaction curves reached full asymptote, this highlights the need for further study due to the high probability of new species being recorded for the studied area.

The helminth community of Tropidurus torquatus (Squamata: Tropiduridae) from a rocky outcrop area located in the state of Minas Gerais, southeastern Brazil, was studied. Ninety-two of the 110 individuals examined (83.6%) harbored helminths. Five species were found, including 3 nematodes (Physaloptera lutzi, Parapharyngodon bainae, and Oswaldofilaria chabaudi), 1 unidentified cestode species, and 1 acanthocephalan cystacanth also not identified. Only the nematode species had sufficient data to perform ecological analysis, with P. lutzi exhibiting the highest prevalence (67.3%). Prevalence between male and female hosts differed only for Oswaldofilaria chabaudi, with males exhibiting the highest values. The intensities of infection by P. lutzi and O. chabaudi were different among male and female hosts, with males also exhibiting the highest values. The host body size was positively related to intensity of infection for all nematode species. Local seasonality had some influence on the helminth community structure. Host diet, sexual dimorphism, and behavior (territorialism, forage strategy) represented important factors for the structure of this parasite community. In general, the helminth community was species poor, depauperate, and non-interactive, representing a typical structure observed in lizard hosts.

The present study investigates the aspects of endocrine cells secreting cholecystokinin, gastrin, insulin, glucagon, somatostatin and serotonin in the enteropancreatic system of Tropidurus torquatus. The specimens were collected in Marambaia Island, Sepetiba Bay, Rio de Janeiro State, Brazil. The animals’ intestine and pancreas were removed, fixed, processed and then subjected to immunohistochemical techniques. Three cell types, immunoreactive (IR) to gastrin, cholecystokinin-8 and serotonin, were identified in the intestinal mucosa. Serotonin was found in the small and large intestines, whereas gastrin and cholecystokinin-8 cells were only observed in the large intestine of T. torquatus. Glucagon, somatostatin and insulin were not observed in the intestines at all. Only glucagon, somatostatin and insulin were identified in the pancreas of the studied lizards. The dorsal lobe showed a large number of endocrine cells scattered throughout the exocrine parenchyma and in the exocrine duct walls. The present study shows that the intestine and pancreas of T. torquatus hold most of the regulatory peptides, presenting a structure similar to that in other vertebrates such as birds and mammals. The endocrine cells identified in the lizards’ enteropancreatic system evidences the good phylogenetic preservation of the regulatory peptides’ molecular structure.

The aim of the present study was to investigate the relationship between nematode infection and the ontogeny and diet of the lizard Tropidurus torquatus from a rocky outcrop in the state of Minas Gerais, south-eastern Brazil. Eighty-nine of 110 lizards examined (81.9%) harboured nematodes. Two nematode species were identified, namely, Physaloptera lutzi in the stomach and Parapharyngodon bainae in the intestine, with prevalence values of 67.3 and 60.0%, respectively. The lizard diet was composed mainly of ants, other hymenopterans, beetles and flowers of the species Centrosema coriaceum (Fabaceae). Host body size was positively correlated with nematode abundance, with adults more heavily parasitized than juveniles. The consumption of C. coriaceum had a negative effect on the abundance of both nematode species, suggesting that this plant may possess anthelmintic properties. The probability of a higher worm burden in adult hosts is likely linked with a longer exposure time to infective stages. Beetles, ants and hymenopterans appear to be the main intermediate hosts for P. lutzi. In general, ontogeny and diet composition determine the structure of the helminth community in this species of lizard.

We studied the reproductive cycle of Tropidurus torquatus in the Cerrado biome of central Brazil from October 1997 to September 1998. Females reached sexual maturity at about 65 mm snout-vent length (SVL), whereas males became sexually mature at 70 mm SVL. Females were reproductively active between August and February, although males contained spermatozoa in the epididymides year-round. Frequency of reproductive females was inversely correlated with precipitation and air humidity and positively correlated with day length. Reproductive activity of males was inversely correlated with air humidity and positively correlated with day length. Females laid six eggs on average and may have produced up to three clutches per reproductive season. With the advancement of the reproductive season, clutches tended to be smaller, whereas egg size remained constant. Fat body mass varied inversely with reproductive activity in both sexes, but females had significantly larger values than males. After an incubation period of approximately 5 months, young emerged at a SVL around 31 mm. Juveniles began to accumulate energy in fat bodies after reaching 47 mm SVL. The fat body cycle and the recruitment pattern of T. torquatus suggest that food resources are not limiting and that the length of the reproductive season is most likely constrained by the availability of microhabitats suitable for egg development.

The button cactus, Melocactus violaceus (Cactaceae), occurs in open, sandy soils in southern Brazilian coastal areas. The fruits of this species are pink, cone-shaped, and have a high water content and low sugar concentration. The fruits of M. violaceus develop while completely protected inside the cephalium and are driven out by internal pressure when ripe. Fruits can be exposed in only a few minutes during the hottest part of the day, and they become easily visible over the cephalium. They are expelled more quickly when temperature is high and lizards are more active. During the dry season these fruits appear to be eaten exclusively by the lizard Tropidurus torquatus (Tropiduridae). The cephalium is positioned close to soil level and the bright color of the fruits apparently improves fruit detection. Lizards defecate viable M. violaceus seeds. These seeds germinated quickly under laboratory conditions, while seeds collected directly from ripe fruits did not germinate under the same conditions. Cactus and fruit morphology, and the diurnal pattern of fruit release, may represent a suite of adaptations for dispersal by Tropidurus torquatus.