Hybridization between populations along the path to complete reproductive isolation can provide snapshots of speciation in action. Here, we present a comprehensive list of salamander hybrids and estimate genetic distances between the parental hybridizing species using one mitochondrial and one nuclear gene (MT-CYB and RAG1). Salamanders are outliers among tetrapod vertebrates in having low metabolic rates and highly variable sex chromosomes. Both of these features might be expected to impact speciation; mismatches between the mitochondrial and nuclear genomes that encode the proteins for oxidative metabolism, as well as mismatches in heteromorphic sex chromosomes, can lead to reproductive isolation. We compared the genetic distances between hybridizing parental species across four main tetrapod groups that differ in metabolic rates and sex chromosome diversity: salamanders, lizards, mammals, and birds. Our results reveal no significant differences, suggesting that variation in these traits across vertebrates does not translate into predictable patterns of genetic divergence and incompatible loci in hybrids.

Homing is a behavior in which an animal returns to a specific place after they have moved or migrated to a distant place. In anurans, most of our knowledge about homing comes from studies in temperate-region species with nocturnal activity and reproduction associated with ponds. Recently, studies with poison frogs (Dendrobatidae) have increased our understanding about homing in tropical frogs with diurnal activity, and that do not breed in large ponds. The Rubí Poison Frog Andinobates bombetes offers a good opportunity to further increase the knowledge of behavioral ecology of homing in anurans because some natural history traits in this species differ from those exhibited in most poison frogs in which homing ability has been studied. For instance, A. bombetes have a smaller body size and use phytotelmata in bromeliads for tadpole development while others use terrestrial pools. To quantify the homing ability and the factors influencing it in A. bombetes, we performed translocation experiments of individuals at distances between 5 and 90 m outside their territory in a forest remnant located in the department of Quindío, Central Andes of Colombia. In this study, we included a large sample size of females, which is important because homing studies with poison frogs has been almost exclusively studied in territorial males. Of 104 displaced individuals, 39 returned to their territory. The probability of homing in A. bombetes was negatively related to the translocation distance, but was unrelated to body size and sex. Apparently, this species has a limited homing ability when compared to most poison frogs studied so far except for O. pumilio, which seems more similar in body size and resources used for reproduction. Overall, homing ability appears to be widely shared in the family Dendrobatidae, Andinobates being the fourth genus of this family for which homing ability has been corroborated experimentally.

We describe a new species of the South American frog genus Adenomera, based on external morphology, color patterns, advertisement call, and mtDNA sequences. The new species was collected from the Japurá River basin in northwestern Brazilian Amazonia and is distinguished from all congeners by the combination of large snout–vent length (SVL), toe tips unexpanded, presence of antebrachial tubercle on underside of forearm, and by a multi-note advertisement call composed of non-pulsed notes. This new species is part of the A. lutzi clade together with a candidate new species known as Adenomera sp. P and A. lutzi. The three species have the largest SVL in the genus. The presence of toe tips fully expanded and a single-note advertisement call distinguish A. lutzi from the new species. Acoustic and morphological data are still required to assess the taxonomic identity of Adenomera sp. P. Our new species of Adenomera is the third anuran species described from the Solimões-Japurá interfluve. This flags this poorly known region of lowland forests as an important area of species richness in northwestern Amazonia.

Assembled here is a reasonably complete list of annotated codes for historical and modern natural history collections associated with lost and extant specimens of fossil and Recent fishes, amphibians, and reptiles. A total of 3,845 codes are anchored to about 2,064 distinct collections and/or institutions in 155 countries. At least 633 of those collections are exclusively paleontological or include fossil specimens. The list is primarily derived from the scientific literature and may serve as a resource for plainly citing specimens in publications and for linking such citations to records in online databases.

Competition for resources between sympatric species can result in reduced fitness. Resource partitioning allows the minimization of competitive pressures, consequently promoting the coexistence of a diversity of species. We tested the hypothesis that the Striped Plateau Lizard (Sceloporus virgatus) and the Ornate Tree Lizard (Urosaurus ornatus) that occur in sympatry in the Chiricahua mountains of Arizona, USA have distinct ecological niches to minimize interspecific competition. We compared the activity times, perch microhabitat characteristics, and diet of these insectivorous lizards to test the prediction that they partition resources. Although we found no difference between the two species in the time at which lizards become active in the morning nor in the composition of their diets, the two species used different structural perch microhabitats. The Ornate Tree Lizard selected higher and narrower perches with more closed canopy than the Striped Plateau Lizard, and males generally occupied higher perches than females. These differences in perch microhabitat use may reduce interspecific competition and allow these two sympatric species to cohabitate.

Fitness attributes acquired in aquatic habitats by amphibians exhibiting complex life histories have been shown to cascade through terrestrial juveniles into adulthood, a phenomenon termed carry-over effects. We explored density-dependent fitness attributes and carry-over effects in Crawfish Frogs (Rana areolata) using a set of field enclosure experiments and a series of field data. Using field enclosures, we hypothesized that 1) at high densities, intraspecific competition would produce smaller Crawfish Frog juveniles that took longer to metamorphose; 2) at high densities, interspecific competition would also produce smaller Crawfish Frog juveniles that took longer to metamorphose; and 3) vertebrate (ambystomatid salamander) predation on Crawfish Frog larvae would reduce survivorship, but by releasing competition pressure would produce relatively larger tadpoles that metamorphosed earlier. Further, we hypothesized 4) that these enclosure results would apply to field data, and that fitness attributes in newly metamorphosed Crawfish Frogs would carry over to first-time breeding adults. Our results confirmed all four hypotheses. Specifically, in Crawfish Frogs, at high densities, both intra- and interspecific competition reduced size (length and mass) at metamorphosis (hypotheses 1 and 2), and predation reduced survivorship and increased size at metamorphosis (hypothesis 3). Finally, we observed density-dependent fitness effects on newly metamorphosed Crawfish Frog juvenile size (length and mass), and carry-over effects from the larval stage on juvenile survival, adult size, and breeding adult numbers (hypothesis 4). In the absence of predators, high densities of intra- and interspecific competitors had no effect on Crawfish Frog larval survivorship. We also present suggestive evidence for compensatory effects. We discuss the potential mechanisms underlying the patterns of these interactions, as well as the role of these relationships in informing management guidelines intended to ensure the future of this species of conservation concern.

<i>Ichthyology & Herpetology</i> (formerly <i>Copeia</i>) publishes work on the biology of fishes, amphibians, and reptiles, or work using those organisms as models for testing hypotheses of broad significance.

Tornabene, Brian J., Smith, Troy W., Tews, Anne E., Beattie, Robert P., Gardner, William M., Eby, Lisa A. (2020): Trends in River Discharge and Water Temperature Cue Spawning Movements of Blue Sucker, Cycleptus elongatus, in an Impounded Great Plains River. Copeia 108 (1): 151-162, DOI: 10.1643/CI-19-256, URL: http://dx.doi.org/10.1643/ci-19-256

Given the conservation status and ecological, cultural, and commercial importance of chondrichthyan fishes, it is valuable to evaluate the extent to which research attention is spread across taxa and geographic locations and to assess the degree to which scientific research is appropriately addressing the challenges they face. Here we review trends in research effort over three decades (1985–2016) through content analysis of every abstract (n = 2,701) presented at the annual conference of the American Elasmobranch Society (AES), the oldest and largest professional society focused on the scientific study and management of these fishes. The most common research areas of AES abstracts were reproductive biology, movement/telemetry, age and growth, population genetics, and diet/feeding ecology, with different areas of focus for different study species or families. The most commonly studied species were large and charismatic (e.g., White Shark, Carcharodon carcharias), easily accessible to long-term established field research programs (e.g., Lemon Shark, Negaprion brevirostris, and Sandbar Shark, Carcharhinus plumbeus), or easily kept in aquaria for lab-based research (e.g., Bonnethead Shark, Sphyrna tiburo). Nearly 90% of all described chondrichthyan species have never been mentioned in an AES abstract, including some of the most threatened species in the Americas. The proportion of female* first authors has increased over time, though many current female* Society members are graduate students. Nearly half of all research presented at AES occurred in the waters of the United States rather than in the waters of developing nations where there are more threatened species and few resources for research or management. Presentations based on research areas such as paleontology and aquarium-based research have declined in frequency over time, and identified research priorities such as social science and interdisciplinary research are poorly represented. Possible research gaps and future research priorities for the study of chondrichthyan fishes are also discussed.

The Tule Perch, Hysterocarpus traskii, is a viviparous and externally monomorphic, internally fertilizing fish. Despite appearing monomorphic, males and females are expected to differ in body shape because the different reproductive roles occupied by the sexes should influence patterns of selection and, ultimately, lead to differences in morphology. The objectives of this study were to determine if the Sacramento–San Joaquin subspecies of Tule Perch (H. t. traskii) exhibit (1) sexual dimorphism in body shape, (2) size-related changes in body shape, and (3) sexual size dimorphism. Geometric morphometric analyses indicated that H. t. traskii exhibited significant sexual dimorphism of body shape and identified the mid-body and caudal peduncle regions as the most effective discriminators between the sexes. Females were narrower through the caudal peduncle and mid-body and had anal-fin origins that were more posteriorly located than males. Additionally, H. t. traskii exhibited significant size-related changes in body shape. Larger fish were deeper bodied with blunter snouts and wider caudal peduncles. The eyes of larger fish were relatively smaller and located higher on the body than those of smaller fish. Hysterocarpus t. traskii did not exhibit differences between the sexes in standard length, but males were significantly heavier than females.