Determining whether organisms have preferences for certain aspects of the habitat is important for understanding the process of habitat selection. Anolis lizards (anoles) have evolved to occupy distinct parts of the arboreal environment. Depending on the population or species, anoles perch on different aspects of the structural habitat varying in diameter, height, and type of substrate. We used laboratory and mesocosm trials to assess whether 2 species of Anolis lizards have preferences for the diameter and type of substrate they use for perching. Results reveal A. cristatellus and A. sagrei both prefer larger diameter perches. Lizards from natural forests and urban populations showed no difference in perch-diameter preference. In contrast, A. sagrei from an urban site overwhelmingly preferred to perch on wood substrates over polyvinyl chloride and metal ones. The larger diameter and wood substrates preferred by anoles in our trials should confer increased locomotor performance for these species based on previous studies. Rapid environmental change caused by humans can decouple the relationship between habitat preferences and fitness, so it is essential to test for changing preferences in organisms that experience urbanization and other forms of global change.

Larval amphibians are important components of ephemeral wetland ecosystems, where they are abundant and perform important ecological functions. Larval pond-breeding salamanders (genus Ambystoma) are the primary vertebrate predators in fishless, ephemeral wetland systems, where they consume large amounts of aquatic invertebrate prey. However, the mechanisms in which larval salamanders affect aquatic communities are poorly understood. We compared stomach contents of larval pond-breeding salamanders from two regions in the midwestern United States to assess their diets for evidence of prey selection. We found larval salamanders exhibited selective predation for certain taxa and functional feeding groups. Our results provide a possible mechanism in which larval pond-breeding salamanders affect aquatic invertebrate communities and shape ephemeral wetland ecosystem processes.

Introduced salmonids can impact aquatic ecosystems through direct predation and indirect effects. We explored the effects of introduced Cutthroat Trout (Onchoryncus clarki) on Boreal Toad (Anaxyrus boreas boreas) survival and habitat use during two aquatic life stages, the embryo and tadpole, at Boreal Toad breeding sites with and without Cutthroat Trout. We found no difference in embryo survival and higher tadpole survival at the site with Cutthroat Trout. Cutthroat Trout are unlikely to use the shallow areas where Boreal Toad eggs are deposited; however, during the tadpole stage, Cutthroat Trout and tadpoles overlap broadly in near-shore aquatic habitats. Frequency of tadpole habitat use is lower in Cutthroat Trout–used areas, but we observed no behavioral or temporal avoidance of Cutthroat Trout by tadpoles. Our results suggest that Cutthroat Trout do not have a negative effect on Boreal Toad embryo or tadpole survival in wild settings and that Cutthroat Trout presence does not preclude tadpoles from using habitats.

Chemical contamination of aquatic environments is widespread, but we have a limited understanding of how contaminants alter critical host–parasite interactions that can influence disease dynamics. We manipulated Northern Leopard Frog (Lithobates pipiens) exposure to pesticides (no pesticides, the insecticide Bacillus thuringiensis israelensis [Bti], or the herbicide atrazine) and trematode-infected (Ribeiroia ondatrae and Echinostoma spp.) snails in outdoor mesocosms. Bti exposure extended host larval period, and atrazine exposure had a nonsignificant trend toward reducing host survival; however, neither pesticide influenced parasite success nor magnified the effects of parasites on their hosts. Parasites negatively influenced tadpole development and, by metamorphosis, parasitized frogs had severe limb deformities and greater mass than unparasitized frogs. The greater mass in parasitized frogs may have resulted from reduced competition between tadpoles and snails for algal resources because parasites decreased snail abundance in mesocosms. Reduced competition between tadpoles and snails may offset the direct negative effects of trematodes on tadpoles, enabling them to survive with high infection intensities. Trematodes may further facilitate their own success by inducing limb deformities that likely increase anuran consumption by definitive hosts. Our results demonstrate how common pesticides and parasites impact amphibians and suggest that, at environmentally relevant concentrations, these pesticides may not dramatically alter host–parasite dynamics.

We present evidence for an incorrect distribution record of Hylodes sazimai and provide a new record of it in the state of Minas Gerais Gerais based on genetic and acoustic data, revisiting the differential diagnosis among its closely related species. The new population is related to the H. sazimai topotypes, with no more than 0.6% of genetic distance. However, the population from Parque Nacional do Itatiaia (PARNA Itatiaia) has a genetic distance varying between 2.7% (2.7–2.8%) from topotypes and 3.3% (3.1–3.3%) from Poços de Caldas specimens. The comparison of these data with the distances between H. sazimai and the other closely related species shows that the population from PARNA Itatiaia is not H. sazimai, nor any other species included in this study. Topotypic H. sazimai has an advertisement call consisting of a sequence of approximately 26 notes lasting around 2 sec and emitted at a rate of 4 calls per minute and 12 notes per second. Hylodes sazimai from Poços de Caldas has an advertisement call consisting of a sequence of about 33 notes lasting around 2 sec and emitted at a rate of 5 calls per minute and 13 notes per second. The random forest approach did not reveal significant discrimination between the populations. Most call features were classified as dynamic for both populations. Because the taxonomic status of the PARNA Itatiaia population is not related to H. sazimai, we suggest a reduction of the northeastern distribution of the species, restricting it to the topotypic locality and Poços de Caldas. Our study reinforces the importance of integrative studies to solve biodiversity crypsis issues and emphasizes the use of detailed acoustic analysis as a powerful tool to diagnosing Hylodes species.

Lizard activity patterns are restricted by both intrinsic and extrinsic variables. The Mexican Plateau Horned Lizard (Phrynosoma orbiculare) is endemic to México and an ambush forager and viviparous species that becomes dormant during the cooler months. The objective of this study was to determine the spatiotemporal activity patterns of P. orbiculare and the environmental conditions related to its occurrence in the natural protected area Statal Park Sierra Morelos, State of Mexico, México. We conducted samplings during 2018 and 2019. We assessed temporal activity patterns with Watson's U² test to determine differences in activity hours between age classes, sexes, and seasons, and we evaluated spatial activity patterns through a hotspot analysis. We conducted a logistic regression model by using landsat 8 bands and indices as independent variables. Differences in temporal activity patterns (activity timing) were detected between age classes and seasons (in the juvenile group) but not between sexes. Within the natural protected area, P. orbiculare aggregated in solar glades. There is an important contribution of ultrablue and blue landsat bands to P. orbiculare occurrence. Differences in activity between age classes could be related to the heat acquisition rate of smaller individuals; meanwhile, no differences between sexes suggests that the thermal optima of females are similar to male optima. Hotspot analysis and the distribution model reveal that P. orbiculare appears on the windward slope where sunrise occurs. Solar glades are important for the species occurrence and should be protected in the studied area. These data allow future monitoring studies to help prevent population declines and illegal extraction.

A warming climate is correlated with phenological shifts in many taxa. We analyzed data from two long-term field studies of three viviparous viperid snakes to examine correlations between temperature and parturition dates. We studied Rock Rattlesnakes (Crotalus lepidus) and Ridge-Nosed Rattlesnakes (Crotalus willardi) over a 31-yr period and Twin-Spotted Rattlesnakes (Crotalus pricei) over a 23-yr period. On average, a 1°C increase in mean daily maximum temperature during mid-April to June, the probable gestation period, was associated with C. lepidus litters being found 6.0 ± 0.84 days earlier and C. willardi litters being found 5.7 ± 1.79 days earlier. We were more likely to find C. pricei neonates during surveys in late July following warm springs and pregnant females in late July following cool springs. Although earlier parturitions could potentially increase maternal survival and improve lifetime reproductive output, warmer temperatures during embryo development could cause unviability or neonate abnormalities. Neonate survival would probably be negatively affected if births occurred before the onset of the summer monsoon rains. Populations of these species that inhabit the highest elevations of mountain ranges will be unable to shift their distributions to maintain the thermal conditions under which they evolved.

For this study, we examined a large sample of museum specimens to ascertain the reproductive ecology of Rhinophrynus dorsalis (Mexican Burrowing Toad) in México. Seasonal aboveground activity was highest during May to August, which tracks monthly rainfall patterns across the region. Contrary to previous assertions, mean body sizes were similar between males and females but females attained larger maximum sizes. Male testis size was largest in May, tadpoles appeared in June, and juveniles were present in July, indicating that most breeding begins in May following the first heavy rains of the year. Few specimens possessed food in their stomachs suggesting that aboveground activity may be more devoted to reproduction than to foraging. The timing of reproduction was variable because most gravid females were encountered during May to August, but some were also present in October and January. Clutch size was estimated to range from 630 to 7,700 eggs, which was positively correlated with female body size. Size to sexual maturity in both males and females was reached in 8–9 mo after metamorphosis and at much smaller minimum and average sizes than previously reported. Adult body size was negatively related to latitude, such that the largest specimens were from the most southern latitudes, especially for males. The reproductive ecology of R. dorsalis resembles distantly related burrowing anurans more so than their close aquatic relatives in Pipidae.

Herein, we describe the external larval morphology, internal oral features, and chondrocranium of Trachycephalus imitatrix and Trachycephalus dibernardoi and the advertisement call of T. imitatrix. To our knowledge, this is the first thorough description of the larval chondrocranium for the genus Trachycephalus. The tadpole of T. imitatrix is overall similar to the other congeneric species, but can be distinguished from them by the following combination of characteristics: presence of two folds in the posterior labium, clumped submarginal papillae, tail ending in a flagellum, buccal roof arena lacking papillae, and seven postnarial papillae. The tadpole of T. dibernardoi can be distinguished from its congeners by the following combination of characteristics: snout rounded in lateral view, absence of interruption in teeth rows, uniseriate and alternated row of marginal papillae, two pairs of infralabial papillae, and absence of projection of the dorsal velum. The advertisement call of T. imitatrix is very similar to that of Trachycephalus nigromaculatus, but can be distinguished from it by its lower dominant frequency. Additionally, both spectral and temporal features of the call can distinguish T. imitatrix from other congeneric species. Our results help understand the differentiation of larval and acoustical characteristics within the genus Trachycephalus.

Terrestrial squamate reptiles from the Galápagos archipelago have limited gene flow among islands, which provides an opportunity to test paleogeographic models. Previous work suggests that Pleistocene glaciations had a strong influence on the evolution of Galápagos's sea-locked vertebrates by allowing dispersal and contact among populations from different islands through land connections for the last 700,000 yr. A prediction of the model is that extant populations, despite being isolated at present, are more genetically similar than would be expected given their age of origin due to recent (Pleistocene) gene flow. Based on mitochondrial genes, we test the prediction with a comparative phylogeographic analysis of two sympatric species of lizards (Microlophus grayii and Phyllodactylus baurii) from Floreana island and two surrounding islets. As expected by the paleogeographic model, lizards from Floreana are very similar genetically to conspecifics from Champion, which, unlike Gardner, was connected to Floreana during Pleistocene glacial maxima. Moreover, populations of Floreana and Champion do not share haplotypes, suggesting that genetic drift played an important role in their evolution. The split between Gardner and Floreana plus Champion populations was estimated at 0.99 million years ago (mya) for Lava Lizards and 3.41 mya for Leaf-toed Geckos, whereas the split between populations from Floreana and Champion was 0.72 and 2.43 mya, respectively. Our results also show that Floreana and Champion populations are part of the same evolutionarily significant unit for each species, which might be at risk due to an upcoming invasive mammal eradication program in Floreana. Therefore, Champion represents a reasonable source for potential reintroductions if necessary.

Desiccation may increase egg and tadpole mortality of anurans that reproduce in temporary ponds. Tadpoles of some species, however, can survive temporarily out of water. Among leptodactylids, desiccation-resistant tadpoles were reported only for species that use terrestrial foam nests for reproduction. To test whether Leptodactylus tadpoles' ability to survive out of water represents an exclusive trait of species with terrestrial nests, we compared survival and resistance to hydric stress of tadpoles of six different species of the Leptodactylus groups and one Physalaemus. We also present an exploratory discussion about the evolutionary association between dehydration-tolerant tadpoles, egg-laying microhabitat, and nitrogen excretion type. Tadpoles were divided into two groups, one staying in 100 mL of water and another subjected to hydric stress on moist paper substrate. Our results indicate that tadpoles resistant to desiccation are not common for all species tested, as only the species with terrestrial nests survived longer and lost less body mass than the other related species. As an estimate, tadpoles of terrestrial-nesting frogs were seven times more resistant to desiccation than those with eggs/nests placed directly into the water. A possible dehydration-resistance mechanism is the premetamorphosis ureotelism that has been shown in terrestrial breeding species with tadpoles that survive some time out of water. Therefore, the capacity of tadpoles to survive a few days after pool drying probably arose from the evolutionary association between terrestrial reproduction and the tadpole ability to prevent body dehydration by a mechanism such as ureotelism.

The state of Florida has the world's highest diversity of established nonnative reptiles, including snakes, lizards, turtles, and crocodilians, most of them introduced from the pet trade. The Spectacled Caiman (Caiman crocodilus) is the only nonnative crocodilian established in Florida, with the earliest date of introduction in 1950. Despite its likely origin being Colombia, the taxonomic identity of the subspecies occurring in Florida remains unknown. We report the first study that resolves the taxonomic status of the population of Ca. crocodilus in Florida based on molecular analysis of samples collected from the 1970s to 2013. We also investigate the probable origin of this population as well as the specimens of the Dwarf Caimans, Paleosuchus palpebrosus and Paleosuchus trigonatus, which have been collected in Florida. We identified only one lineage of Ca. crocodilus in Florida, corresponding to Caiman crocodilus fuscus, and our results indicate the Magdalena River basin in Colombia as the most likely area of origin. We also correct the identification of Paleosuchus recorded in Florida and identify the Guiana Shield, and specifically Guyana, as the most likely region from which these specimens were introduced.