Understanding why turtles select specific localities to nest over others is important for management and conservation. For some species of freshwater turtle, the same localities are selected year upon year, but it is uncertain whether these localities are selected due to favored environmental conditions, or natal-site homing. The Mary River Turtle (Elusor macrurus) is an endangered freshwater species from Australia, and nesting data gathered between 2004 and 2011 demonstrated that female E. macrurus select to nest in specific localities along the Mary River. Here, we used time-lapse infrared photography and image-identification analysis to assess whether the same individuals returned to the same nesting banks over three consecutive years (nest-site fidelity), and we compared the physical and soil characteristics of nesting areas against other localities along the river where the turtles were not recorded to nest. The photography study illustrated that some females returned to nest at the same locality over consecutive years, whereas others did not; therefore, it is still inconclusive whether E. macrurus exhibits true nest-site fidelity. Preferred nesting areas were all northerly facing and thus exposed to higher levels of solar radiation than nonpreferred areas with similar soil and physical characteristics. Consequently, the preferred nesting areas exhibited significantly greater mean and daily fluctuations in the nest temperature compared with other areas with dummy nests. We suggest that the warmer nest temperature would speed up embryo development; therefore, female E. macrurus select to nest on northerly facing banks in an attempt to reduce the embryo incubation period. A possible reason for this behavior may be to reduce their exposure to nest-raiding predators. The study highlights importance of key nesting areas along the Mary River for the conservation of E. macrurus.

Natural and sexual selection are frequently invoked as causes of sexual size dimorphism in animals. Many species of turtles, including the Diamond-backed Terrapin (Malaclemys terrapin), exhibit sexual dimorphism in body size, possibly enabling the sexes to exploit different resources and reduce intraspecific competition. Female terrapins not only have larger body sizes but also disproportionately larger skulls and jaws relative to males. To better understand the relationship between skull morphology and terrapin feeding ecology, we measured the in-lever to out-lever ratios of 27 male and 33 female terrapin jaws to evaluate biomechanics of the trophic apparatus. In addition, we measured prey handling times by feeding Fiddler Crabs (Uca pugnax), a natural prey item, to 24 terrapins in the laboratory. Our results indicate that although females have disproportionately larger heads, they have similar in:out lever ratios to males, suggesting that differences in adductor muscle mass are more important in determining bite force than jaw in:out lever ratios. Females also had considerably reduced prey handling times. Understanding the factors affecting terrapin feeding ecology can illuminate the potential roles male and female terrapins play as top-down predators that regulate grazing of Periwinkle Snails (Littorina irrorata) on Cord Grass (Spartina alterniflora).

We estimated growth rates of Dwarf Caiman (Paleosuchus palpebrosus) with capture–recapture data from 40 individuals collected over 6 yr in streams surrounding the Brazilian Pantanal, near the southern limit of the species' distribution. Repeated recaptures of eight animals indicate that within-individual variation is much greater than between-individual variation, possibly reflecting climatic influences. Growth rates of juveniles increased linearly until individuals were about 28 cm snout–vent length (SVL), and then growth rates decreased gradually after attaining that size. The rate of decrease, however, differed between males and females. Data for 30 juveniles with known age were used to validate the growth curve based on the growth rate-on-size analysis. The length of the smallest female recorded nesting (SVL = 60 cm) allowed us to estimate the age at first reproduction to be about 8 yr for females. Our data do not support our initial hypothesis that P. palpebrosus would have slow growth rates and relatively old age at first reproduction, as has been suggested for Paleosuchus trigonatus.

Survival, growth, and fecundity are considered as the three main components of the life cycle of any living organism. The relative contribution of these three components to average fitness may vary drastically among populations of single species. Examining this interpopulation variation and understanding its causes can provide insight on the particular selection pressures that drive phenotypic divergence among populations. We conducted a demographic study of eight distinct populations of the viviparous lizard Sceloporus grammicus in central Mexico. We estimated variation among populations in stage-specific survival, growth, and fecundity. Using these data we constructed site-specific population projection matrices to estimate population growth rates, which we interpreted as measures of the average fitness of each population. Elasticity analysis was used to calculate the relative contribution of the three life-cycle components to population growth rates. The three life-cycle components had relatively high elasticity values, which meant that survival, growth, and fecundity contributed similarly to fitness. However, some variation was found among populations. We searched for potential associations between the observed interpopulation variation in these measures of relative importance for average fitness and interpopulation variation in temperature, rainfall, population density, microhabitat availability, degree of human-induced disturbance, and overall mortality. None of these environmental factors or their interactions could explain the observed interpopulation variation in the relative importance of the life-cycle components. Our results provide insight about how these viviparous lizards allocate resources to survival, growth, and fecundity in different environments.

Sexually dimorphic coloration that plays a role in social signaling during stereotypical displays is well known in lizards. Previous studies on a large Australian agamid lizard (Eastern Water Dragon, Intellagama lesueurii) documented male-biased sex differences in ventral coloration, but males were not observed to use postures that displayed their ventral surfaces. Male resource-holding potential (RHP) was determined by body size, with the largest individuals controlling territories in preferred riparian habitat. Both large males that defended territories and those that did not had fully developed ventral coloration. Together these observations suggested that male ventral coloration does not play a role in social communication in male Water Dragons. We tested this hypothesis by recording the behavior of free-ranging males during baseline social conditions and when the level of aggression was much higher because we temporarily removed and then reinstated territory owners. Male Water Dragons performed three behavior patterns that displayed their conspicuous ventral coloration when engaged in agonistic encounters with same-sex rivals, especially when social conditions among neighboring males were unstable. Rival males responded to these displays in all instances. A large, model Water Dragon male in which we manipulated ventral color elicited lower-intensity responses from rival males when the model ventral surface was red than when it was brown. This result is also consistent with the hypothesis that red coloration plays a role in signaling and perhaps in intimidation of rivals. Water Dragon displays that revealed ventral coloration were not given when males interacted with females, suggesting red coloration does not function in advertisement to potential female mates. Our results support the hypothesis that red ventral coloration in Eastern Water Dragons functions in advertisement to rival males similar to the function of red coloration in several other vertebrates.

The lizards Podarcis muralis and Iberolacerta horvathi display an overall similarity in morphology and ecology. Although they are widely sympatric in part of their distribution range of Slovenia, areas of altitudinal segregation have been observed. Ecophysiological traits such as preferred body temperatures (T_p) and rates of evaporative water loss (EWL) are some of the factors likely to be subjacent to this pattern. We expect the species that is more abundant in higher altitudes to have lower T_p and higher EWL (due to lower environmental temperatures at higher elevations) than the species that is more abundant in lowlands. We conducted lab experiments to determine whether intra- and interspecific variation in these two physiological traits exists. Contrary to expectations, the means of T_p were similar between the species, but their seasonal dynamics differed, which indicates that thermal accuracy might be more important. Species differed in seasonal (and daily) variation of T_p, rising from spring to summer more in P. muralis than in I. horvathi. Comparing instantaneous EWL, our results showed interspecific differences with higher values in P. muralis than in I. horvathi. Throughout a 12-h period, the accumulative EWL was also always higher for P. muralis than for I. horvathi, with the greatest differences occurring after 9–12 h of the experiment. Further studies should focus on investigating if these divergent physiological characteristics of both species are associated with their habitat use (in terms of thermal and water environment) and species interaction.

The introduction of exotic tree species may interfere with conservation efforts for natural habitats, including grasslands in coastal sand dunes. Natural plant cover is used by several species in coastal dunes of Buenos Aires, Argentina, among them the lizard Liolaemus wiegmannii. Here we study the habitat use and abundance of this lizard inhabiting a psammophytic grassland within this ecosystem, where Acacia longifolia was recently introduced. Surveys and lizard sampling were conducted along 40 transects distributed in four independent zones of 75 ha, each with a different degree of invasion impact. We measured structural and thermal features in relation to A. longifolia and native plants. The lizard L. wiegmannii was three times more abundant in zones with ≤ 25% coverage of A. longifolia. The Jacobs selectivity index showed that all age classes selected native shrubs and avoided A. longifolia trees. These results were similar in greenhouse experiments. However, we found no differences in the use of any of these plants' (introduced or native) leaf litter. Structural and thermal characteristics of the habitat under the shrubs seemed to be more favorable for the physiological performance and behavior of L. wiegmannii, whereas the lower temperatures under A. longifolia might explain the lower presence of lizards in areas where this tree was introduced.

We describe a new species of Trachycephalus from the Amazon Rain Forest, which is morphologically similar to T. resinifictrix (Goeldi). This new species is characterized by a medium body size for species in the genus (males snout–vent length [SVL] 57.9–74.3 mm, females SVL 74.4–84.9 mm); skin of the head not co-ossified with underlying dermal bones; dorsal skin texture, including that of the head, densely glandulous with several tubercles; paired vocal sac that protrudes at a posterior angle to the jaw when inflated; iris coloration pinkish-beige with a horizontal black bar and a vertical thin black line below the pupil; dorsal color pattern consisting of a wide interocular whitish-beige and a dark blotch on the middle of the dorsum joining the crossbar at the top of the dorsum, forming a “T” shape; rounded snout in dorsal view, and rounded or acuminate in profile; well-developed supratympanic fold; ulnar tubercles present, sometimes associated with ulnar fold; well-developed axillary membrane; well-developed tarsal fold; males with nonhypertrophied forearm; minimum frequencies of the advertisement call lower than 0.38 kHz; pulse rate 126.7–146.6 pulses/s; tadpole external coloration with brown reticulated blotches in the superior portion of the fin; tooth row formulae 2(2)/4. The new species, which is widely distributed in the Amazonian Forest, has been confused with the parapatric T. resinifictrix. It is a canopy treefrog that breeds in tree-holes that have accumulated rainwater.

A new species of the genus Allophryne is described and, in contrast to its congeners that occur in the Amazon Basin, is based on specimens obtained in Uruçuca, State of Bahia, in the Atlantic Rain Forest of eastern Brazil. Allophryne relicta sp. nov. is characterized by a medium body size for the genus (snout–vent length range 19.9–21.9 mm in males); large head (head width about 35% of SVL); large, red-orange eyes, with a large black transversal stripe on iris; dorsum covered by few tubercles and many scattered black dots; dorsolateral surfaces cream with dark brown, elongate, anastomosed spots, and venter clear gray with scattered small white tubercles; presence of a line of tubercles on the ventrolateral surface of forearm; advertisement call formed by a multi-pulsed note of 0.509 ± 0.029 s in duration and emitted at intervals of 1.287 ± 0.500 s, with notes composed of 28.58 ± 1.84 pulses at a dominant frequency of 3828 ± 82.28 Hz; call-note emission rate of 34.46 notes/min and pulse emission rate of 56.13 ± 1.25 s. The molecular phylogeny supports the placement of A. relicta sp. nov. as sister taxon of a clade formed by A. resplendens A. ruthveni.