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The selection of a foraging habitat may be driven by food availability or by the cost associated with the use of that habitat. This basic tradeoff can lead individuals in the same population to occupy different habitats in response to perceived risk levels. In the southeastern United States, plethodontid salamanders are often observed climbing vegetation, which represents a potential foraging habitat. We examined whether diet composition of the Red-legged Salamander, Plethodon shermani, differed between salamanders found on vegetation and on the ground surface. Contrary to the results of a previous study, we found that the overall number and mass of prey items did not differ between salamanders in these two microhabitats. Furthermore, we found no evidence that the relative use of different prey categories varied in relation to a salamander's selected microhabitat. Although salamanders of all body sizes had consumed a diverse range of prey items, we found evidence of an ontogenetic shift in prey utilization, with smaller salamanders consuming a significantly greater number of prey items than larger salamanders while there was no relationship between body size and mass of prey consumed.
A new species of Leporinus in the L. cylindriformis group is described from the Río Orinoco basin, Venezuela. This new species can be separated from congeners by the combination of an extremely dorsoventrally slender body, the presence of a prominent midlateral spot positioned ventral to the dorsal fin, and the absence of any other intense dark pigmentation. The new species is most similar to L. aripuanaensis from the Rio Aripuanã, Brazil, but can be most easily differentiated from that species by the absence (79% of specimens) or faint presence (21% of specimens) of a circular dark spot over the hypural plate in the new species, versus the presence of an intensely pigmented dark spot in that position, respectively. It can be further distinguished from L. aripuanaensis by the modal number of predorsal scales (12 versus 11). Small juveniles of the two species do not differ morphometrically, but their allometric growth trajectories differ. Above 70 mm SL, the new species differs from L. aripuanaensis in interorbital width (34–44% HL versus 30–34%) and eye diameter (29–34% HL versus 26–30% HL). This new species represents the most recent of a long series of newly discovered taxa within Leporinus and reinforces the Orinoco Basin as a region of high endemism.
Inferring the natural distribution and native status of organisms is complicated by the role of ancient and modern humans in utilization and translocation. Archaeological data and traditional cultural use provide tools for resolving these issues. Although the painted turtle (Chrysemys picta) has a transcontinental range in the United States, populations in the Desert Southwest are scattered and isolated. This pattern may be related to the fragmentation of a more continuous distribution as a result of climate change after the Pleistocene, or translocation by Native Americans who used turtles for food and ceremonial purposes. Because of these conflicting or potentially confounded possibilities, the distribution and status of C. picta as a native species in the state of Arizona has been questioned in the herpetological literature. We present evidence of a population that once occurred in the vicinity of Winslow, Arizona, far from current remnant populations on the upper Little Colorado River. Members of the Native American Hopi tribe are known to have hunted turtles for ceremonial purposes in this area as far back as AD 1290 and possibly earlier. Remains of C. picta are known from several pueblos in the vicinity including Homol'ovi, Awatovi, and Walpi. Given the great age of records for C. picta in Arizona and the concordance of its fragmented and isolated distribution with other reptiles in the region, we conclude that painted turtles are part of the native fauna of Arizona.
Human activities dramatically increased the amount of reactive nitrogen in the environment through the widespread production and application of fertilizers, generation of human and livestock waste, and combustion of fossil fuels. This excessive nitrogen load eventually reaches water bodies and at circumneutral or acidic pH accumulates in the form of nitrate, nitrite, and ammonium. Our objective was to test if prolonged exposure to low and environmentally relevant concentrations of nitrate, nitrite, and ammonium could affect survivorship, growth, and behavior of tadpoles of a Brazilian amphibian species, the gladiator frog Hypsiboas faber. Tadpoles of H. faber were exposed to 0, 2.5, and 10 mg.L−1 of nitrogen as nitrate, nitrite, and ammonium in a 21-day static renewal test. We demonstrated that under prolonged exposure even relatively low concentrations of inorganic nitrogen can cause lethal and sublethal effects on anuran larvae. Nitrate, the most abundant form of nitrogen in nature, caused no effects even in the largest manipulated concentration. Tadpoles exposed to 10 mg.L−1 N-nitrite had decreased growth and survivorship relative to controls. However, such nitrite concentrations are uncommon and generally found only in highly polluted, anaerobic conditions. In turn, tadpoles exposed to 10 mg.L−1 N-ammonium (which is within the upper range of concentrations observed in nature) had reduced activity rates and survivorship relative to controls. Future studies that aim to assess the environmental risk of nitrogen contamination should expand monitoring of concentrations in natural habitats, assess ontogenetic variation in organismal sensitivity, and evaluate the effects of synergistic interactions between inorganic nitrogen and other physical, chemical, or biological stressors to amphibian larvae.
Identifying cryptic biodiversity is fundamental to evolutionary biology and to conservation efforts. This study investigated range-wide genetic diversity of Gopher Frogs, Lithobates capito, across the southeastern United States coastal plain to determine implications for taxonomy and conservation. We collected data for two mtDNA regions in 21 populations to identify genetic structure across the geographic distribution of the species. Based on population genetic, phylogenetic, and genealogical analyses, we recovered three reciprocally monophyletic mtDNA lineages corresponding to mainland coastal plain populations and two lineages within peninsular Florida. Breakpoints for these lineages did not occur in previously identified hotspots of amphibian phylogeographic breaks and did not follow currently recognized subspecies designations. We recommend these lineages be recognized as separate distinct population segments and be considered separately by the U.S. Fish and Wildlife Service for listing under the Endangered Species Act. Additionally, we propose an evolutionary hotspot for amphibians that deserves further attention.
Otothyropsis alicula is described from the Rio Santo Antônio, Rio Grande basin, upper Rio Paraná drainage, Brazil. The new species is distinguished from its congeners by having a unique color pattern in the caudal fin, rectangular dorsal-fin spinelet, short pectoral-fin spine and first pelvic-fin ray, suture between contiguous bifid neural spines two-thirds the distance from the vertebral centrum to their distal tips, absence of an odontode crest on the posterior portion of the parieto-supraoccipital, and other morphometric and meristic features. An updated identification key to the species of Otothyropsis is provided.
Otothyropsis alicula é uma nova espécie proveniente do Rio Santo Antônio, bacia do Rio Grande, alto Rio Paraná, Brasil. A nova espécie é diagnosticada dos demais congêneres por possuir padrão de colorido único na nadadeira caudal, spinelet da nadadeira dorsal retangular, espinho da nadadeira peitoral e primeiro raio da pélvica curtos, sutura entre os espinhos neurais bífidos com cerca de dois terços da distância entre o centro vertebral e a sua margem distal, ausência de uma crista de odontódeos na porção posterior do parieto-supraocipital, e outras características morfométricas e merísticas. Uma chave de identificação atualizada para as espécies de Otothyropsis é apresentada.
Hatchling green turtles (Chelonia mydas) were recorded emitting sounds at Ascension Island, South Atlantic Ocean, on 19 May 1978. Analysis revealed that the 70 sounds recorded could be separated into four sound categories. The sounds were complex and characteristic of a contact call, and were similar to those recently reported in other species of aquatic turtles. The relationship between the structure and frequency of the sounds and levels of predation on turtle eggs and hatchlings, especially by ghost crabs (Ocypode spp.), warrants further study.
Brilliant and conspicuous coloration in animals is often thought to signal quality to conspecifics (sexual selection) or to signal unpalatability to predators (aposematic selection). Ambystoma maculatum (spotted salamanders) have bilateral rows of conspicuous bright yellow dorsal spots against dark skin. Although this coloration has been long thought a classic example of warning coloration, to date, there are no quantitative measures of spot coloration. We captured adult male and female A. maculatum as they entered breeding ponds and measured body condition, spectral reflectance of the yellow spots, spot size, and coverage of the dorsal area in spots. We found evidence of sexual dichromatism; males had a larger area of their dorsum covered in spots, and tended to have more chromatic, but less bright yellow color. Moreover, our data suggest a tradeoff between coloration and body condition. Animals in better body condition expressed lower chroma and those with greater spot coverage expressed brighter spots and lower yellow chroma. Although these data are not entirely consistent with the predictions of sexual selection, they suggest a physiological tradeoff associated with coloration that has not been documented in salamanders.
The classification of the North American darters (Percidae: Etheostomatinae) has been a subject of historical interest and rigorous debate. Conflicting morphological and molecular phylogenetic analyses have made relationships among species unclear and have hampered attempts at classification. Recently we showed that amplified fragment length polymorphism (AFLP) data provide support for relatively ancient relationships (>30 mya) among darters that are consistent with numerous morphological hypotheses. We predicted that increasing the number of extant species sampled would result in a more accurate estimate of evolutionary relationships and increase the statistical resolution, particularly at deeper nodes, as it would increase the probability that two taxa share homologous alleles (fragments) and link deeper relationships, thus overcoming noise created by homoplasious fragments. To test this prediction, we added 32 species to our original analysis of 69 species and reconstructed evolutionary histories using Bayesian methods for AFLPs to infer phylogenetic relationships. Overall resolution of the tree substantially improved. Bayesian Posterior Probabilities were strong (greater than 0.95) at most of the deeper nodes, and most notably increased to 0.97 and 0.99 BPP at the two most ancient and previously weakly supported nodes in Etheostoma (estimated divergence approximately 26.1–33.5 mya). Our results indicated that dense taxon sampling may be necessary to increase accuracy and resolution when reconstructing ancient evolutionary relationships using AFLPs. Results of the present study were compared with earlier classifications and with recent studies on phylogenetic relationships to identify best-supported genera and subgenera.
Understanding species–habitat relationships is important for achieving effective habitat management goals, but few studies have evaluated habitat use in co-occurring turtle species. We examined habitat partitioning among five species of freshwater turtles at an isolated preserve in northeastern Illinois. From May–September 2006, we conducted a radio-telemetry study to determine differences in macro- and microhabitat use, niche breadth, and niche overlap of 50 turtles representing rare (Emydoidea blandingii, Clemmys guttata) and common species (Chrysemys picta, Chelydra serpentina, Sternotherus odoratus). Both levels of habitat analysis showed strong partitioning between C. guttata and the common species as well as marked overlap in habitat use between E. blandingii and C. serpentina. Use of mesic dolomite prairie was greater in C. guttata compared to S. odoratus. Further, use of pond was greater in all common species compared to C. guttata and E. blandingii. Species strongly partitioned microhabitat along an axis comprised of vegetation height, understory canopy cover, water depth, and percent open water at surface, as well as in use of wetlands with organic substrates. Patterns of macro- and microhabitat use and measures of niche breadth and niche overlap suggest that E. blandingii and C. serpentina are habitat generalists whereas C. guttata is a habitat specialist. We found no evidence of agonistic interactions among species, thus habitat partitioning observed in our study is likely a result of species-specific traits and requirements. Our findings suggest that C. guttata is most vulnerable to habitat degradation and that variation in wetland habitat characteristics is necessary to support a diverse freshwater turtle community.
Field metabolic rates (FMR) and water influx rates (WIR) were measured in Gila Monsters (Heloderma suspectum) in the Mojave Desert of southern Nevada. Gila Monsters had rates of energy use that were less than half of those expected for lizards of their size, including species that live in arid habitats. Free-living Gila Monsters also had comparatively low water flux rates. The annual energy requirements of adult Gila Monsters averaged approximately 3,766 kJ, with two-thirds of the total (2,533 kJ) allocated to activity while above ground, and one-third to resting metabolism (1,233 kJ; mostly while below ground). Unusually low rates of resting metabolism caused relative costs of activity to be high: compared to other lizards, Gila Monsters have among the highest proportional use of energy for activity, relative to total energy use. The average annual water expenditure of adults was approximately 775 mL, and lizards achieved positive mass balance by drinking rain water during the late summer monsoon season. Drinking may be critical in meeting annual water requirements. FMR and WIR differed between seasons but were both highest in early summer (mid-May through June), coinciding with the peak of foraging and breeding activities. Levels of above-ground activity significantly influenced both FMR and WIR, whereas body temperature while burrowed influenced only WIR, and body mass (over the range of 270 to 420 g) did not significantly influence either whole-animal FMR or WIR.
Snakes can respond to variation in resource availability through changes in diet and species interactions. For many species, however, patterns of variation in diet are poorly known. Making use of novel 13C, through the provision of supplemental food in the form of milo (Sorghum spp.) for Northern Bobwhite (Colinus virginianus), we used carbon (δ13C) and nitrogen (δ15N) stable isotope analyses to evaluate the specificity of mammalian and herpetofaunal diet, trophic niche width, and trophic niche overlap between five snake species in the Red Hills of the southeastern United States. Most mammalian prey and Northern Bobwhite were characterized by different δ13C values in the milo- and non-milo-treated areas. Using milo to reflect dietary patterns we determined that Coachwhip (Masticophis flagellum), Cottonmouth (Agkistrodon piscivorus), and Eastern Rat Snake (Pantherophis alleghaniensis) were dietary generalists, revealed by larger isotopic range and lack of correspondence between isotopic values and those of distinct prey groups. In contrast, Black Racer (Coluber constrictor) and Corn Snake (Pantherophis guttatus) were dietary specialists. Black Racers fed largely on herpetofauna, and δ13C values of Corn Snake revealed a gradual ontogenetic/size-related diet shift from herpetofauna to a mammalian-based diet. There was considerable overlap of isotopic trophic niche between snake species, except for the Cottonmouth with δ15N values higher than other sampled species. These findings provide novel insight into snake trophic ecology.
Sexually dimorphic coloration has been widely suggested to play a role in sexual selection and speciation. Animal colors can originate from several different biochemical pathways, which may underlie different patterns of selection and diversification. Darters of the speciose genus Etheostoma exhibit substantial diversity in male breeding coloration. We used digital photography and image software to comprehensively quantify male coloration in the Rainbow Darter (Etheostoma caeruleum) and the Orangethroat Darter (E. spectabile). Color traits differed across species, populations, and body sizes, with size differences contributing the most to individual color variation. The bluish colors were overall more strongly correlated with size than the reddish colors. Conversely, the reddish colors tended to be less correlated with size and better indicators of species and population identity. Finally, we determined that the bluish colored tissue contained a chromoprotein pigment, and that the reddish colored tissue contained a carotenoid pigment. The patterns of conservation and diversification in darter male coloration provide a guide for future investigations into their functional and evolutionary significance.
A new species of Aspidoras (Corydoradinae) is described from the Serra dos Carajás, lower Tocantins River basin, representing the northernmost record of the genus at the edge of the Brazilian Shield into the Amazon basin. Aspidoras gabrieli is easily distinguished from all congeners by having the rays and interradial membranes of the dorsal and pectoral fins entirely and densely pigmented, the inner bony margin of the pectoral spine expanded as a narrow laminar shelf with edge smooth or scarcely serrated; lateral-line canal posterior to the two anterior lateral-line ossicles absent (also in A. taurus), naked predorsal region (also in A. velites and A. psammatides), large brown oval spots on the flank and caudal peduncle that sometimes merge to form irregular patches (also in A. maculosus, A. albater, A. lakoi, and A. depinnai), and several additional morphometric distinguishing features. Comments on generic allocation and interspecific relationships are presented.
Uma nova espécie de Aspidoras (Corydoradinae) é descrita da Serra dos Carajás, bacia do baixo rio Tocantins, representando o registro mais ao norte na bacia Amazônica, na borda do Escudo Brasileiro. Aspidoras gabrieli é facilmente distinta das demais espécies do gênero pelo padrão de coloração das nadadeiras peitoral e dorsal inteira e densamente pigmentadas sobre os raios e membranas inter-radiais, pela margem interna da porção óssea do espinho peitoral estendida em uma estreita lâmina de borda lisa ou suavemente asserreada, pela ausência de canal da linha lateral após os dois ossículos anteriores da linha lateral (exceto A. taurus), por apresentar a região pré-dorsal nua (exceto A. velites e A. psammatides), por apresentar grandes manchas marrons aproximadamente ovais nos flancos e pedúnculo caudal que às vezes se unem formando grandes manchas irregulares (exceto A. maculosus, A. albater, A lakoi e A. depinnai), e por várias diferenças morfométricas. Comentários sobre alocação genérica bem como relações interespecíficas são apresentados.
The genus Spatuloricaria is diagnosed by a number of conspicuous characteristics that set it apart from other genera in the subfamily Loricariinae. The genus has a broad geographical distribution extending from Argentina to Panama. Despite the flood of new loricariid taxa described in the past decades, no new species of Spatuloricaria have been newly reported since 1945. In this paper, we report on a distinctive new species of the genus from the Rio Xingu and Rio Tapajós in the Amazon basin. The new species is distinguished from congeners by the lack of abdominal and preanal plates, in combination with the presence of five transversal dark-brown bands on the dorsum. It apparently is the only species in Spatuloricaria where males are smaller than females, a situation opposite of that in other species of the genus.
The debate over the species status and geographic distribution of Rhinichthys atratulus and R. obtusus has persisted for decades. Morphological analyses have led to ambiguous results making field identifications possible in only some areas, further complicating the unclear and conflicting taxonomic histories of these species. In this study, we clear up some of these identification issues by analyzing two mitochondrial genes and nine microsatellite loci amplified from Blacknose Dace across the eastern half of North America. Our results show large genetic differences between R. atratulus and R. obtusus for both mitochondrial genes and microsatellites. We determine that R. atratulus inhabits streams east of the Appalachians from Nova Scotia to Virginia and the southern part of the eastern Great Lakes; R. obtusus inhabits the remaining regions west of the Appalachians to approximately Minnesota, eastern Nebraska, north into the Manitoba province and Mobile Bay drainage.
Marine turtle species consist of several genetically discrete ‘evolutionarily significant units’ (ESUs) which do not interbreed. We studied Flatback turtle (Natator depressus) hatchlings from two rookeries (Mon Repos Conservation Park and Bare Sand Island, Australia) representing two separate ESUs. Turtles from these ESUs differ in several key life history traits, including body size, and we predicted hatchlings would also differ in locomotor performance. We also investigated the proportion of hatchlings with non-modal scute patterns to determine whether this varies between ESUs. We collected newly emerged hatchlings, and measured mass, carapace length and width, and recorded the scute pattern. We then measured self-righting ability and crawling speed. Our results confirmed a difference in hatchling size between the two ESUs, with Mon Repos rookery hatchlings being larger. However the size difference did not translate into a difference in self-righting ability or crawling speed. The Mon Repos rookery also produced a larger proportion of hatchlings with major non-modal scute pattern compared to Bare Sand Island rookery. The differences suggest hatchling survival rates may differ between ESUs, and that ESUs should be studied separately when implementing conservation measures.
Electric glass knifefishes of the genus Distocyclus, family Sternopygidae, are reviewed. Features previously utilized to diagnose Distocyclus were found uninformative as to whether the two species originally assigned to the genus are sister taxa. Distocyclus goajira was found to lack the derived features present in the type-species of the genus, D. conirostris and instead shares derived features with Archolaemus, Eigenmannia, and/or Japigny; however, the relationships of Distocyclus goajira among those genera cannot be resolved. In light of this evidence, Distocyclus is restricted to its type species, D. conirostris, which is defined on a series of derived characters, and D. goajira is assigned as incertae sedis in the Eigenmanniinae under a new combination of “Eigenmannia” goajira. Distocyclus conirostris is redescribed on the basis of multiple samples from across the Amazon, Essequibo, and Orinoco river basins.
Os peixes elétricos do gênero Distocyclus, família Sternopygidae, são revisados. Os caracteres diagnósticos previamente propostos para Distocyclus se mostraram não informativos em relação as duas espécies originalmente alocadas neste gênero como espécies irmãs. Distocyclus goajira não apresenta os caracteres derivados presentes na espécie tipo do gênero, D. conirostris, e ainda compartilha caracteres derivados em diferentes combinações com Archolaemus, Eigenmannia e Japigny. Baseado na presente evidência, Distocyclus é restringido a sua espécie tipo, D. conirostris que é definido por uma série de caracteres derivados e D. goajira é considerada incertae sedis em Eigenmanniinae, sob a nova combinação de “Eigenmannia” goajira. Distocyclus conirostris é redescrito com base em várias amostras ao longo das bacias dos rios Amazonas, Essequibo e Orinoco.
Development of the caudal fin skeleton of capelin, Mallotus villosus, is described based on observations of cleared-and-stained specimens from a wild caught growth series ranging in size from 4.2 mm notochord length (NL) to 144 mm standard length (SL). The sequence of chondrification and ossification for each element is described and compared with that of related salmonoid and esocoid fishes. Caudal fin elements are first chondrified in specimens that are 8.9 mm NL and all elements are ossified by 52 mm SL. In general, hypaxial elements (e.g., parhypural, hypurals, hemal arches and spines of preural vertebrae) develop before epaxial elements (e.g., epurals, uroneurals, neural arches and spines of preural vertebrae). Preural centra are among the last elements to form in the caudal skeleton of M. villosus. Interestingly, preural centrum 1 does not form. The caudal fin skeleton morphology of adult M. villosus is nearly identical to that of other osmerid species, and the developmental sequence of the caudal skeleton of M. villosus more closely resembles species of the Salmonoidei than Esocoidei. A ventral-to-dorsal developmental gradient in the caudal fin elements and anterior-posterior gradient in development of vertebral centra are discussed.
Droughts represent a major disturbance in lotic systems, and likely negatively influence stream-inhabiting amphibian populations. However, because of the inability to predict droughts, empirical investigations examining the response of stream amphibians to drought are uncommon. We conducted a capture–mark–recapture (CMR) study of a population of Eurycea cirrigera (Southern Two-lined Salamander) at one stream from 2005–2010; during this five-year period several drought events occurred. This stochasticity provided an opportunity to examine the effects of drought on survivorship and capture probability of E. cirrigera. We found that capture probability was influenced by season and drought conditions. We also found that salamander survival was influenced by drought; monthly survivorship decreased from 0.96±0.03 during non-drought conditions to 0.79±0.03 during drought conditions. Our results suggest that drought leads to decreased survivorship of E. cirrigera and the effects of drought on capture probability varies by season. Increased capture probability, especially during the reproductive season, may be a result of salamanders seeking refuge in the stream as opposed to seeking refuge in the adjacent terrestrial environment.