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.

Dispersal and nesting philopatry are two processes that affect the connectivity, evolution, and long-term viability of populations, and thus have important conservation implications for threatened and endangered species. Here we investigate dispersal, relatedness, and the fine-scale spatial genetic structure of Eastern Box Turtles (Terrapene carolina carolina) at the northern extreme of their geographic range in northwestern Michigan. We analyzed georeferenced microsatellite genotypes (n = 165) using global, sex-specific, and two-dimensional local spatial autocorrelation (2D LSA), as well as spatial principal components analysis (sPCA). Genetic diversity was low relative to Eastern Box Turtle populations in the middle of the range. We found dispersal was male-biased, as only females showed significant positive spatial genetic autocorrelation at distances less than 2 km. 2D LSA showed local genetic “hotspots” of related turtles that tended to correspond with known nesting areas. We found evidence for global genetic structure using sPCA, which we attribute to genetic clustering rather than clinal variation. Our results suggest that restricted female dispersal and fidelity to limited open-canopy nest sites result in fine-scale spatial genetic structuring in this population. We stress the importance of maintaining high quality nesting habitat and habitat corridors for transient males, which appear to be critical for functional connectivity of Eastern Box Turtles.

In freshwater turtles, movements have been shown to be influenced by seasonal changes in water levels, with members of the family Podocnemididae exhibiting some of the longest nesting migrations yet documented. In this study, we quantified linear home range sizes and seasonal movements of the Magdalena River Turtle (Podocnemis lewyana) using capture–mark–recapture and radio-telemetry techniques. We marked 924 turtles and recaptured 7.8% of these individuals one or more times, thereby documenting the movements of 41 juveniles, 13 males, and 18 females. Turtle movements differed significantly among sex/size classes, with males moving more. While 85% of all individuals had estimated linear home range sizes of less than 1 km, one juvenile moved 3.1 km, one female moved 2.5 km, and one male moved 4.8 km. We also obtained data on the movements of six reproductively mature females using radio telemetry. We documented seasonal movements out of channels into wetland or riverine habitats, increasing the estimates of total distance traveled for this sex/size class to a mean of 13.8 km (range = 6.9–18.7 km), with greater displacements documented during low water periods. Together, our results show that individuals of P. lewyana in the middle Magdalena River drainage occupy limited linear home ranges, but that reproductively mature females make extensive displacements during low water periods, presumably related to their need to access nesting beaches in riverine habitats. There are currently no protected areas within the range of this endemic species, but our results argue that any reserve created for protecting this critically endangered turtle must be large enough to cover all of its habitat requirements, including nesting beaches in the dry season that are separated from habitat where they maintain stable home ranges during the remainder of the year.

The White Shark (Carcharodon carcharias) is a top predator cosmopolitanly distributed and heavily protected worldwide. Identification and information pertaining to White Shark nursery areas is limited yet crucial for the protection of sharks during their most vulnerable life stages. Here, we present morphometric, skeletal, and haplotypic characteristics of the smallest free-living White Shark reported to date (1066 mm TL). These characteristics correspond to a newborn White Shark smaller than those previously reported in an embryonic state but displaying the same number of rows of functional teeth as an adult. The individual was caught incidentally by an artisanal fishery operating along the Pacific coast of Baja California, near the international border between Mexico and the United States (USA). We found no genetic divergence between Isla Guadalupe and central California, two aggregation sites that have been proposed as a possible source for newborn sharks in this area. The newborn White Shark displayed the most common haplotype present among individuals at both aggregation sites. These findings provide evidence suggesting the presence of an extended nursery habitat in the Northeast Pacific, a transnational region between Mexico and USA.

Target enrichment of conserved nuclear loci has helped reconstruct evolutionary relationships among a wide variety of species. While there are preexisting bait sets to enrich a few hundred loci across all fishes or a thousand loci from acanthomorph fishes, no bait set exists to enrich large numbers (>1,000 loci) of ultraconserved nuclear loci from ostariophysans, the second largest actinopterygian superorder. In this study, we describe how we designed a bait set to enrich 2,708 ultraconserved nuclear loci from ostariophysan fishes by combining an existing genome assembly with low coverage sequence data collected from two ostariophysan lineages. We perform a series of enrichment experiments using this bait set across the ostariophysan tree of life, from the deepest splits among the major groups (>150 Ma) to more recent divergence events that have occurred during the last 50 million years. Our results demonstrate that the bait set we designed is useful for addressing phylogenetic questions from the origin of crown ostariophysans to more recent divergence events, and our in silico results suggest that this bait set may be useful for addressing evolutionary questions in closely related groups of fishes, like Clupeiformes.

The inshore Tropical Eastern Pacific (TEP) comprises two major biogeographic provinces, the Cortez Province and Panamic Province, which are distinguished mainly by environmental differences between equatorial and subtropical regions. It is important to evaluate the influence of these environmental differences in limiting the connectivity of populations of fishes inhabiting both provinces and therefore shaping the phylogeographic patterns along the inshore TEP. Here, we used analyses based on sequences of the mtDNA control region to identify phylogeographic patterns of two snapper species, Lutjanus guttatus and L. peru, found in the coastal TEP. In both species, we found high levels of genetic diversity and a lack of genetic differentiation—as measured by both genetic fixation and genetic differentiation indices—between populations from the Cortez and the Panamic provinces. Our results suggest no significant effect of environmental differences between equatorial and subtropical waters in these two provinces on genetic differentiation, which may be explained by oceanographic features that promote larval dispersal and gene flow.

Accurate, comprehensive data on life expectancy, growth rates, age structure, and sexual maturation are necessary to inform decision-making for conservation action, but they are often difficult to obtain from wild animals. Osteohistology has proven a reliable method for accessing chronological data in extant and extinct vertebrates. Traditional mark–recapture methods require repeated measurements in the field and do not allow comparison with far more extensive data from specimens housed in museum collections, thus reducing statistical power and inviting unjustified extrapolation. We investigate longevity and growth in the large-bodied iguanian lizard Sauromalus ater (Common Chuckwalla). We find highly variable growth to be typical for S. ater occupying a spectrum from rapid growth to sexual maturity within two to three years leading to above-average body size later in life or slow growth early in life with sexual maturity at four to eight years followed by growth to body sizes around the average adult size. We show individual S. ater achieve final body size in about ten years, not decades, and that body size and age in adults are significantly correlated. This study suggests conflicting reports on growth, maturation, longevity, and generation cycle in S. ater are all correct and reflect complex ontogeny in squamates.

Including early life history data in assessments can improve fisheries management by increasing our knowledge of stock structure, spawning habitat, and population trends. The identification of fish larvae to species is a necessary step in using early life history data toward this goal. Three species of hakes from the genus Urophycis are common on the northeast United States continental shelf: U. chuss or Red Hake, U. regia or Spotted Hake, and U. tenuis or White Hake. Unfortunately, identification of larval Urophycis has long been only possible at the genus level. Larvae of Urophycis (n = 277) collected in a subset of ethanol-preserved samples were identified genetically through sequencing of the cytochrome oxidase I gene and were used to update morphological descriptions with characters that separate these three species at the larval stage. Sequencing occurred in two stages: the first (n = 88) to develop a set of known-identity larvae to define species-specific traits, the second (n = 189) to test morphological identification based on the traits described in this study. We describe a combination of the location of dorsal and ventral pigment, head pigment, lower jaw pigment, and the timing of development of the pectoral fins to distinguish the larvae of these three species at sizes <6 mm. Using molecular techniques to improve morphological identifications is a powerful and efficient way to obtain the species-level data needed for assessments and management.

The new species, Cirrhilabrus briangreenei, is described on the basis of the holotype and six paratypes collected from mesophotic coral ecosystems of the Verde Island Passage, Philippines, between depths of 82 and 110 m. The new species is most closely related to Cirrhilabrus pylei, but it differs primarily in the presence of: more pored scales on the posterior lateral line (7–9 vs. 5–6); a lower number of circumpeduncular scales (14 vs. 16); a lower number of gill rakers (16–17 vs. 18–20); and differences in coloration details of the dorsal and caudal fins. Both species differ from all other congeners in sharing the following combination of characters: pelvic fins very long (56.5–70.0% SL), often extending past anal-fin terminus in males; caudal fin scintillating and iridescent in males; dorsal fin with sinuous scribbling in both sexes; anterior dorsal fin with a metallic blue spot on first one to two interspinous membrane spaces; snout with three parallel stripes from maxilla to anterior edge of orbit; and rest of head with a network of short broken pinstripes in both sexes. These characters are also distributed in part amongst other species of Cirrhilabrus, in particular, C. katoi, C. lineatus, C. rhomboidalis, and C. rubrimarginatus, and their putative relationships are discussed on the basis of meristic, morphometric, and molecular sequence data. We briefly comment on the variability of morphological characters within Cirrhilabrus and their implications towards phylogenetic classification, with remarks on methods for data collection for species of Cirrhilabrus.

The structure and functioning of freshwater turtle communities remain understudied topics, especially in tropical regions where biodiversity is higher. The objective of our study was to compare the diets of Podocnemis erythrocephala ,P. expansa, P. sextuberculata, and P. unifilis living in syntopy in Amazonas, Brazil. We tested for qualitative and quantitative variations in the way different species used the same available food resources. We collected fresh stomach flushings from all turtles captured in trammel nets in three lakes in 2012. Sampling was conducted in the four distinct tropical seasons: beginning of rainy season (rising water), peak of rainy season (rapidly rising water), end of rainy season (highest flooded forest water level), and dry season (when water levels were receding). We tested the hypothesis that different food items are available in different quantities at different times of the year due to the seasonality of fruiting trees and other plants in response to the wet and dry conditions. We examined whether food items consumed were related to turtle body size and if there was feeding niche overlap among species. Podocnemis sextuberculata consumed the least amount of food by volume, while P. expansa consumed the highest diversity of food items. All four species are primarily herbivorous, and their diets were composed mainly of fruits and seeds (85.4% mean proportion by volume). Genipa americana (Rubiaceae) was most important in the diet of all species, except in P. sextuberculata. We found some evidence of seasonal differences in the consumption of some plant species. Body size did not influence qualitative (diversity of food items eaten) or quantitative variation of food items (volume), except in P. erythrocephala for which we detected a significant linear relationship between carapace length and the volume of stomach contents. The highest food niche overlap was between P. expansa and P. unifilis, and the lowest niche overlap was between P. erythrocephala and P. sextuberculata. Turtles tended to partition food resources more in areas that had more species feeding in syntopy than in areas with fewer syntopic species.

Nongenetic inheritance—involving epigenetic, behavioral, or environmental factors—is increasingly viewed as being important in development and evolution. Here, we describe a possible novel form of nongenetic inheritance in the tadpoles of the Mexican Spadefoot (Spea multiplicata): the transmission of information about the environment from dead individuals to living individuals of a later cohort or generation. When we exposed live tadpoles to the remains of desiccated conspecifics from a naturally occurring dry pond, we found that they used phenotypic plasticity to adjust their development in ways that would increase their chances of escaping a drying pond. Specifically, compared to their siblings that were reared with soil lacking tadpole remains, those reared with soil containing desiccated conspecifics grew larger, developed faster, and were more likely to express an alternative, environmentally induced phenotype—a distinctive carnivore morph that is favored in rapidly drying ponds. We also found evidence of underlying genetic variation in the plasticity to produce carnivores, suggesting that this plasticity could mediate adaptive evolution when populations experience different environmental conditions. Such a tendency of living individuals to respond to cues associated with dead individuals from a previous generation may be vital in giving each generation a head start in their environment.

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.

While organisms are typically considered permanent residents of a community, many transient organisms occupy a community for only brief periods. Despite the duration, the effects of a short visit by a top predator may remain long after departure. To test hypotheses on the impacts of a short-term visit by a top predator on pond communities, we used artificial ponds and constructed food web treatments that varied in trophic structure (Control Food Web = no predators present, Bluegill Food Web = only intermediate predators present, and Full Food Web = top and intermediate predators present). The constructed food webs were replicated five times and contained two prey species (frog tadpoles), an intermediate predator (fish), and one top predator (freshwater turtle). The Full Food Web simulated a four-day visit by Chelydra serpentina (Common Snapping Turtle). Predation by Lepomis macrochirus (Bluegill) reduced mean tadpole survival for Hyla chrysoscelis (Cope's Gray Tree Frog) in all food webs, including the Full Food Web with C. serpentina, compared to the Control Food Web. Although C. serpentina had no effects on tadpoles of H. chrysoscelis, the top predator reduced mean survival and increased mean mass of Rana sphenocephala (Southern Leopard Frog) when compared to the Bluegill Food Web. Therefore, our results suggest that brief visits from transient organisms, especially top predators, can alter community structure and initiate cascading effects.

In southern Florida, Gopher Tortoises (Gopherus polyphemus) occupy mesic flatwoods and Florida scrub communities where habitat and climatic conditions differ from other portions of the species' range. Both of these habitats appear suboptimal for tortoises due to saturated soils in mesic flatwoods and low forage abundance in scrub. Nonetheless, these habitats support large numbers of tortoises in southern Florida, albeit at low intensities. We assessed influences of elevation and microtopography on the spatial distributions of tortoise burrows and examined burrow use patterns within six sites at Avon Park Air Force Range in south-central Florida. The six sites differed in dominant soil types and vegetation communities, allowing comparisons of burrow distributions among mesic flatwoods, Florida scrub, and mixed flatwoods-scrub habitats (two replicate sites each). Point-process modeling identified significant influences of microtopography on burrow intensities that superseded the effects of site-wide elevation trends in five of the six sites. The effects of microtopography were most pronounced in flatwoods, suggesting greater reliance on areas of slightly higher elevation in mesic habitat, presumably in response to saturated soils and frequent flooding. Burrow use patterns during an exceedingly wet year also suggested that tortoises respond behaviorally to unsuitable hydrology by moving frequently among burrows that were flooded with groundwater. Microtopographic variation may be an important predictor of small-scale habitat use for fossorial reptiles, especially in mesic soils, which could be readily explored using increasingly available LiDAR-derived elevation data combined with the modeling approach demonstrated here.

Riverine fishes are sensitive to human-induced changes to their ecosystems and have experienced substantial declines in the past century. The presence and operation of dams modifies natural flow regimes thereby disrupting cues that signal migration and negatively influencing habitats critical to riverine fishes. Blue Suckers (Cycleptus elongatus) make large annual movements, require large and unfragmented reaches of river, and may be sensitive to modifications of cues that initiate migration. We assessed the influence of individual and abiotic factors on home ranges and movements of 62 transmittered Blue Suckers from 2006–2014 in the Missouri River upstream of Fort Peck Reservoir in Montana. Populations in this area are disjunct from those downstream and are influenced by upstream dam regulation. Blue Suckers used large expanses of river with overall home ranges ∼88 river kilometers, but these home ranges were about two times smaller than reported elsewhere. Increasing discharge and water temperature were associated with movement rate and movement probability and cued spawning movements of Blue Suckers. Movement rates increased with discharge to peak and decreased thereafter. Surprisingly, movement rate and probability were highest at the lowest water temperatures we observed (∼1–5°C) unlike previous studies in other systems when peak movement occurred at ≥10°C. Blue Suckers aggregated and showed interannual fidelity to several locations during spawning. Aggregation and fidelity suggest that optimal spawning areas, which exist in tributaries, may be limited within our study area. Our results support evidence that riverine fishes require natural trends in discharge and water temperature, including occasional flood pulses and connectivity among seasonal habitats. The Upper Missouri River retains pseudo-natural discharge and temperature regimes that elicit responses of Blue Sucker to environmental cues, but other rivers may not. Preserving or restoring these features, and entire riverscapes, would maintain natural environmental cues and habitats required by riverine fishes to complete their life histories.

Information about the life history of larval fishes can be sparse, especially at the edges of typical geographic ranges and among fishes for which there is no commercial fishery. We report a new observation of larval Arctic Shanny (Stichaeus punctatus) far south of their typical geographic range in the western North Atlantic. Only two previous records of adult of S. punctatus have been documented in this region, and there has only been one previous report of larvae in US Atlantic waters. From May through July 2018, we observed large numbers of larval S. punctatus by night-lighting off a dock at Shoals Marine Laboratory on Appledore Island, Maine, in the Gulf of Maine. We include approximations of catch per unit effort (number of larvae per ten-minute sampling interval) throughout the sampling period and information regarding identifying features. The high number of larvae seen could indicate that the Isles of Shoals is a spawning locality for this species and could indicate a future increase in their abundance in the southern Gulf of Maine.

We describe two new cryptic species of Bufo within the subgenus Anaxyrus discovered in Central Nevada of the western United States. Our analyses revealed that these two localized endemic toads are genetically divergent and morphologically distinct, yet were concealed under the range of the broadly distributed western toad (Bufo boreas), which occurs throughout Nevada. The newly discovered species are close in geographic proximity to each other (albeit, in different hydrological basins) but have evolved unique morphological characters that are distinct from each other and distinctive from all allied taxa within the B. boreas species complex. The delimiting of these two rare toads emphasizes the link between taxonomic crypsis and inadequate conservation as these newly described species are vulnerable to extinction due to severely restricted geographic ranges, unknown population sizes, and dependency on rare, fragile wetland habitat, which is a limited resource within Nevada, the primary state that makes up the arid Great Basin. These two endemics join the Great Basin B. boreas species complex as imperiled new members, and our study demonstrates that our knowledge of anuran diversity is incomplete and that new discoveries can still be made, even in unlikely settings.