Several aquatic sampling techniques are commonly used to detect and quantify amphibian larvae. Although many techniques have been standardized, comparisons among methods have been poorly studied. We employed a removal design to investigate the detection rate of amphibian larvae using box enclosures and evaluated the reliability of timed dipnet sampling relative to the more quantitative box enclosure sampling across 13 vernal pools. For these comparisons, we studied larvae of the endangered California Tiger Salamander (Ambystoma californiense; CTS) and the smaller and more abundant tadpoles of the Pacific Treefrog (Pseudacris regilla; PTF). Based on N-mixture model estimates, box enclosure sampling captured only 5% more of the CTS larvae present than PTF tadpoles, despite disparities in their sizes and estimated abundances. Dipnet sampling was slightly more effective at detecting CTS larvae than was enclosure sampling, while both methods equally detected PTF tadpoles. We found a strong relationship (R² = 0.92) between the densities of CTS larvae estimated from dipnet sampling and those calculated from the more quantitative enclosure sampling, indicating that dipnet sampling is a reliable measurement of relative abundance. We conclude that timed dipnet surveys can be an important tool for monitoring populations of CTS, and possibly other lenticbreeding amphibians, especially given its relative efficiency that can be replicated across both time and space.

In order to understand the macroecological architecture of an amphibian metacommunity of a large southern European region located between the Eurosiberian and Mediterranean domains (Galicia), we analyzed nestedness from matrices of presence–absence of 14 species in 3,627 water points, including both ponds and streams, along an altitudinal gradient (0–2,036 m), during a 11-yr period (2003–2013). To quantify nestedness, we used the metric NODF (nested overlap decreasing fill). We also explored interannual variability in nestedness and in temporal patterns of alpha, beta, and gamma diversity. The maximally packed matrix for ponds showed a nested pattern at middle and high elevation, whereas for streams, the nested pattern occurred at low elevation. In both types of wetlands, the magnitude of nestedness was moderate, around 15–30%. On the other hand, nestedness was not found to increase or decrease over the study period, for both ponds and streams, or at the three levels of elevation. This temporary stability was also found for alpha, beta, and gamma diversities. The moderate nestedness pattern detected was most likely explained by selective removal of species, a poor connection among water points, historical destruction of wetlands, or major land-use changes associated with the abandonment of traditional farming activities. Our results denote a certain resilience to human disturbance by the studied amphibian species. However, these results stress the need of protecting the metacommunity as a whole (because of the relative importance of species turnover among sites), and emphasize the suitability of preserving the old mosaic landscape at least within protected areas. Our results are intermediate between those expected for the temperate zone and those expected for lower latitudes, likely because the study region is a biogeographical transition area.

In many species, males are larger and more colorful than females. This has often evolved by sexual selection, and the sexual dimorphism and dichromatism is observed once individuals reach adulthood. Such sexual differences are presented by Collared Lizards, Crotaphytus collaris. However, sexual dichromatism of a different sort than that expressed in adults is seen in juveniles before their first brumation. Late-season juvenile males develop bright orange dorsolateral bars and begin to defend territories and form pair bonds with females. Furthermore, the largest, late-season, putative juvenile males have mature sperm on their hemipenes. Paternity analyses using polymerase chain reaction of eight microsatellite loci revealed that a significant number of putative juvenile males, which were not seen during intensive fieldwork at our study site the following year, sired offspring with females who were juveniles, yearlings, or adults in the fall. Either females were fertilized by these males in the fall (and those females either stored sperm or arrested development of embryos overwinter), or they were fertilized by surviving fall juvenile males (i.e., yearlings) early the next spring, who subsequently died before we began our spring-summer field surveys. The majority of our data indicates the second possibility is true. First, adults and yearlings of both sexes begin brumation in the fall, weeks or months before October when larger putative juvenile males display sexual dichromatism and have mature sperm on their hemipenes. Females of these age classes are not available for copulation in October but are in early spring. Second, we collected juvenile females from the field in October and held them individually without exposure to males in the laboratory through brumation and beyond through spring and summer. None of these females became gravid. Our results indicate that although putative juvenile males possess mature sperm in the late fall, they wait until the following spring to fertilize adults of all age classes. Many of these males subsequently die early in the season but attain (posthumous) fitness by mating early in the spring before yearling and adult males become fully territorial and sexually active.

Habitat management and species conservation plans are increasingly important as biodiversity losses increase. For many species, we lack the necessary data to implement habitat management or conservation plans because the species may be rare or difficult to detect, particularly at the periphery of geographic ranges. This may be especially true for snakes. For example, Pygmy Rattlesnakes (Sistrurus miliarius) have state-level protection at the northern terminus of the range but what little is known about the species in this region is derived from just 30 observations collected over the past 40 yr. This leaves considerable uncertainty regarding conservation status and establishes a need to better understand habitat suitability and their geographic distribution. Therefore, the objectives of our study were to determine landscape-scale environmental variables that influence patterns of distribution for S. miliarius in the northern extent of its range via the Maxent Species Distribution Algorithm coupled with on-site monitoring via standardized road-cruising transects (n = 43) to evaluate model suitability. The resulting species distribution model showed that suitable habitat (∼2045.96 km²) was composed primarily of riparian areas that exist in isolated patches. These habitats were primarily composed of sandy soils and low-elevation forested areas. Our on-site monitoring, informed by our modeling efforts, resulted in 12 new records for the species (an increase of 28.57%). Collectively, our species distribution model suggests that suitable habitat for S. miliarius within our study area is restricted to riverine or riparian habitats associated with the Lower Tennessee River Valley. The methods used in this study employ a strategy to better understand suitable habitat for rare or secretive species that occur across large geographic areas.

The bromeligenous genus Crossodactylodes, endemic to the Atlantic Forest domain and the “campo rupestre” ecosystem in Brazil, currently comprises five named species. Three additional putatively new species have already been proposed in a recent study based on mitochondrial and nuclear markers. Here we employ phenotypic data to corroborate the distinctiveness of one of these lineages, and describe it as a new species, from the Espinhaço Mountain Range in the municipality of Itamarandiba, state of Minas Gerais, southeastern Brazil. We also provide information on its natural history and conservation status. The new species is diagnosable from its congeners by a combination of characters, including the presence of vocal slits in adult males, the orange coloration of discs on fingers and toes, and the presence of vomerine odontophores. The new species is the second Crossodactylodes to be reported for the campo rupestre and it was only recorded in a small forest patch composed of low trees, shrubs, mosses, lichens, and a high density of bromeliads.