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Quantifying patterns of habitat use by riverine species is logistically challenging, yet instream habitat characteristics are likely important in explaining the distribution of species. We integrated radiotelemetry and sonar habitat mapping to quantify instream habitat use by female Barbour's Map Turtles (Graptemys barbouri) in Ichawaynochaway Creek, a tributary to the Flint River. We used logistic regression and a Bayesian information-theoretic approach to evaluate habitat use relative to habitat availability based on random locations. Over the two-year study period, turtles used an average of 839±199 m of creek length and exhibited site fidelity (mean 50% kernel density = 0.23±0.05 ha). Substrate was generally more predictive of habitat use of female G. barbouri compared to large woody debris and water depth. Turtles generally used deeper habitats close to rocky-boulder and rocky-fine substrate with greater amounts of large woody debris. Estimates of home range size and habitat use found in this study improve our understanding of the spatial ecology of G. barbouri and provide a baseline for their habitat use in a relatively undisturbed section of stream. It is imperative to understand the spatial ecology of species, such as map turtles, that are particularly vulnerable to indirect effects of habitat modifications caused by impoundments, sedimentation, pollution, and snagging.
Hybridization is more common in actinopterygian fishes than any other group of vertebrates. This is especially true for members of the family Cyprinidae; for example, Hubbs found 68 different combinations of inter-generic and intra-generic hybridization among cyprinids collected east of the continental divide. Hybridization between two cyprinid species, the red shiner and the blacktail shiner (Cyprinella lutrensis and C. venusta), has been described in detail in Georgia where C. lutrensis is an introduced species. However, hybridization has not been thoroughly assessed where the two species are naturally sympatric. Our specific objectives were to determine the extent of ongoing hybridization between the two species using nuclear markers and morphometrics and to determine the extent of historical introgression using mitochondrial DNA (mtDNA). We collected 100 individuals from four different locations along the Bosque River and an additional 100 individuals from four locations along the Paluxy River. We used amplified fragment length polymorphism (AFLP) to verify species identification and determine hybrid status of each individual. A total of 56 AFLP fragments were scored, with 82.14% (47 fragments) being polymorphic (95% criterion). Based on these nuclear markers, we only identified two hybrids out of the 200 specimens analyzed; one from the Bosque River, Texas and one from the Paluxy River, Texas. There were no instances of introgression of mitochondrial DNA (mtDNA) from one species into the nuclear background of the other species. We did, however, discover the sympatric occurrence of three mtDNA lineages of C. lutrensis within a single nuclear gene pool; there was only one mtDNA lineage of C. venusta. Overall body shape was assessed using a truss network and was found to be statistically different with red shiner having the shorter and deeper body. The minimal amount of hybridization inferred from AFLP data, in combination with the absence of mtDNA introgression and limited morphological overlap, indicates that pre- or postzygotic isolating mechanisms effectively minimize genetic exchange between naturally sympatric populations of C. lutrensis and C. venusta within these two river systems.
We herein describe Characidium satoi, new species, only known from its type locality at Rio Curral das Éguas, a small tributary of Rio Abaeté, in the Rio São Francisco basin, Brazil. It can be distinguished from its congeners by the following characteristics: area between the pelvic fin and the origin of anal fin moderate to strongly convex in lateral view; presence of irregular and discontinuous bars, forming dorsal blotches separated from ventral V-, W-, or diamond-shaped marks; and the first anal-fin radials inserted between the fifth and sixth caudal vertebrae. The juveniles and mature females of Characidium satoi, new species, have smooth fin rays, while mature males have hooks on pelvic and, in some specimens, pectoral and dorsal fins. Moreover, females and immature males have irregular bars on dorsum and fuzzy vertical bars on body; during the breeding season, males develop uniformly darker pigmentation on body and head, lacking any distinctive vertical bar on body. This seasonal color dimorphism is reported in the family Crenuchidae for the first time.
Pethia striata, new species, is described from the Tunga River in Kudremukh National Park, in the central part of the Western Ghats, Karnataka State, India. The new species is distinguished from its congeners by the combination of the following characters: absence of barbels; stiff and serrated last unbranched dorsal-fin ray; complete lateral line with 20–21 pored scales and a relatively small humeral spot one scale below the fourth lateral-line scale; a large black blotch covering lateral-line scales 17–19. In addition, the outer edges of body scales are dark, producing a striped pattern along the sides of the body. Pethia striata, new species, is presently known only from headwater-streams of the Tunga River basin.
Reaching developmental milestones younger and at larger sizes is commonly claimed to reflect increased fitness. However, the amount of fitness gained from being larger and younger at a milestone may vary with several attributes, particularly evolutionary history, life history, and environmental characteristics. We used a meta-analysis to investigate whether these attributes affected the utility of developmental milestones to be used as predictors of future fitness. We chose amphibian size at and time to metamorphosis (SAM and TTM, respectively) as model developmental milestones, because studies have examined SAM and TTM's efficacy for fitness prediction (via post-metamorphic fitness proxies), and they are commonly used in a variety of studies testing ecological and evolutionary theory and more applied research on the effects of anthropogenic stressors. We found variation in the predictive power of SAM and TTM for post-metamorphic performance. SAM was a more consistent predictor of post-metamorphic performance than TTM, but also had a higher sample size. Life history and study design (i.e., laboratory vs. field studies), but not evolutionary history, were important for explaining variation in predictive power for post-metamorphic performance. The correlation between SAM and performance increased with the proportion of time to maturity reached at metamorphosis, suggesting that species can compensate for initial fitness reductions through ontogeny. Because numerous researchers use size and age at developmental milestones to indicate fitness, we urge caution in interpreting their results due to the species- and system-specific nature of fitness surrogates.
In lizards, signal patches play a role in sexual selection, both in interactions among and between sexes. The size and shape of a signal patch may be used by males to determine if another individual is of the same or opposite sex. Males may confuse other males for females, or vice versa (i.e., sexual confusion) if the signal patches overlap in size and shape between males and females. As a result, the confused male may perform courtship displays to an intruding male or display aggression toward a female. Sexual confusion has been documented in Sceloporus cowlesi and is attributed to overlap in signal patch morphology between the sexes. But it is unknown how common this pattern is among other Sceloporus lizards. To make inferences about sexual confusion at the species level, we compare the morphology of signal patches between males and females in three species of Sceloporus lizards (S. consobrinus, S. cowlesi, S. tristichus) to test for adequate differences in signal patch size to prevent sexual confusion. Our results suggest that due to similarities in patch size between the sexes of both S. cowlesi and S. tristichus sexual confusion may be occurring.
Chicken Turtles (Deirochelys reticularia) are morphologically adapted for carnivory, and this specialization has been corroborated by diet studies of the eastern and Florida subspecies (D. r. reticularia and D. r. chrysea, respectively). However, the diet of the western subspecies (D. r. miaria) has not been examined. To investigate this important aspect of this subspecies' ecology, we collected 54 fecal samples from 22 adult D. r. miaria and 13 samples from nine juvenile D. r. miaria in southeastern Oklahoma. White River Crayfish (Procambarus acutus) were found in 88.9% of adult samples (mean of 2.3 crayfish per sample), and appeared to be the dominant food source for adults. There was a significant positive relationship between turtle size and crayfish size, and on average the crayfish were 29.8 mm in carapace length. Insects representing six orders (predominantly Hemiptera and Coleoptera) were found in 57.4% of adult fecal samples. Surprisingly, plants were present in 92.6% of adult fecal samples. While most of the plant matter was unidentifiable, Common Rush (mostly seeds; Juncus effusus), Broadleaf Cattail (Typha latifolia), Giant Cutgrass (seeds; Zizaniopsis miliacea), and Purple-fringed Riccia (Ricciocarpus natans) were identified in several fecal samples. There was a significant difference between the diets of juveniles and adults, with juveniles consuming more insects, fewer crayfish, and fewer plants than adults. These results suggest both that there is an ontogenetic shift in the diet of D. r. miaria and that, unlike the other subspecies, D. r. miaria is demonstrably omnivorous.
In most amphibians, females are the larger sex presumably due to selection for larger reproductive output. Sexual selection may, however, produce larger males and also lead to the evolution of secondary sexual characteristics. The proximate causes of sexual dimorphism are related to differences in growth rates and longevity, but these data are scanty for most amphibian species and often depend on long-term demographic studies. Here we use skeletochronology and mark–recapture data obtained on a weekly basis over five years to investigate the sexual dimorphism in body size and shape, growth, and longevity of two toad species, Rhinella rubescens and R. schneideri, in the Cerrado of central Brazil. In adult individuals of both species, males have more robust forelimbs than females, but females attain larger asymptotic body sizes. In Rhinella rubescens, females have wider heads, whereas in R. schneideri, females bear larger parotoid glands and higher heads than males. Females of R. rubescens grow faster and reach sexual maturity earlier than males (♀: 105 days, ♂: 170 days); in contrast, males of R. schneideri grow faster and attain sexual maturity earlier than females (♀: 450 days, ♂: 340 days). The estimated age of the oldest males and females, respectively, were three and 3.5 years for R. rubescens and five and four years for R. schneideri. Males of R. rubescens were frequently captured a few months after reaching sexual maturity, between six months to one year of age, whereas in R. schneideri, males were frequently captured when sexual maturity was reached from one to 1.5 years of age. Our data indicate that sexual dimorphism results from different growth trajectories before and after sexual maturity. Differences between the two species in morphology, growth, and longevity likely reflect their separation into two morphologically and phylogenetically distinct sister clades.
Omnivory is ubiquitous in aquatic and terrestrial ecosystems and may increase stability of food webs. Turtles are long-lived and among the most abundant organisms in lentic aquatic habitats. Many species are omnivores and thus may be especially important in regulating ecosystem dynamics in these systems. Turtles are also one of the most threatened vertebrate groups in the world; if they indeed play pivotal roles in lentic ecosystems, their declines may disrupt or even destabilize those ecosystems. In order to assess the role of turtles in an aquatic ecosystem, we examined sources of primary production, trophic structure, and ontogenetic diet shifts of five species of turtles, other herpetofauna, and fish in a large shallow lake in northern Florida. Stable isotope analyses (δ13C and δ15N) of 42 species of animals and five sources of primary productivity revealed that macroalgae and/or particulate organic matter were the foundation of the food web. Trophic structure of the herpetofauna and fish indicated a high degree of omnivory (TPs of 3–4), few specialists at high trophic levels (TP ≥ 4.0), and few strict primary consumers (TP = 2.0). Several predatory fish (Micropterus salmoides, Lepomis gulosus, and Pomoxis nigromaculatus) and herpetological predators (e.g., Alligator, Nerodia) were functionally trophic omnivores with trophic positions lowered by predation on primary and low trophic position secondary consumers. We found two major divisions in the trophic structure of turtles—an herbivore (Pseudemys floridana) and four omnivores (Apalone ferox, Chelydra serpentina, Sternotherus odoratus, and Trachemys scripta). There were at least three types of omnivores, species that are generalist feeders throughout their life (e.g., C. serpentina, S. odoratus), species that change their trophic position during ontogeny (e.g., A. ferox), and species with the same trophic position through ontogeny but resulting from different diet composition as juveniles and adults (e.g., T. scripta). Trophic position of some species indicated that even when turtles are primarily predatory, they also function as vegetative consumers and facultative scavengers (e.g., T. scripta, S. odoratus, A. ferox). Given that omnivory is a critical process that can stabilize food webs, there will certainly be dramatic shifts in how energy and nutrients flow through these lentic ecosystems if turtle populations decline.
Genetic data are increasingly being applied to re-evaluate past taxonomic hypotheses and better understand the evolutionary patterns and connectivity among regional populations of cosmopolitan species. This is of particular importance for heavily exploited, commercially important species. The phylogenetic structure of the Yellowtail Jack, Seriola lalandiValenciennes, 1833, was investigated using genetic data from 42 individuals collected from California, the Pacific coast of Baja California (Mexico), the Gulf of California (Mexico), New Zealand, Japan, South Africa, and Chile. An analysis using S. dumerili as an outgroup and combining the sequences of two mitochondrial genes (CR and COI) and four nuclear genes (RAG2, EHHADH, UBE3A, MLL) was used to determine the level of genetic divergence among samples from different geographic regions. Bayesian and Maximum Likelihood analyses utilizing combined mitochondrial gene (mtDNA) or nuclear gene (nucDNA) data supported the existence of multiple regionally restricted clades with mtDNA analysis identifying four major clades and nucDNA supporting three. Both mtDNA and nucDNA trees were very similar in topology, which was reflected in the combined total evidence phylogram. These clades were highly supported with Bayesian posterior and bootstrap probabilities ranging from 90 to 100 percent for the three major clades that were recovered in both mtDNA and nucDNA trees. These clades represent regionally specific specimens collected from the 1) Northeast Pacific, 2) Northwest Pacific, and 3) Southern Hemisphere. Morphometric analysis (MDS and ANOSIM) of available meristic data on the number of soft dorsal-fin rays, anal-fin rays, and total number of gill rakers separated specimens among the three regions identified by genetic analysis (P = 0.05). Based on the phylogenetic structure within this taxonomic unit as evidenced by genetic data and significant meristic differences among these regional lineages, we conclude that three cryptic species currently bear the name Seriola lalandiValenciennes, 1833. We propose the resurrection of two currently available names based on nomenclatural priority. The Northwest Pacific species name should revert to Seriola aureovittataTemminck and Schlegel (1845) (type locality Japan), and the Northeast Pacific species to Seriola dorsalisGill (1863) (type locality Cabo San Lucas, Mexico). Seriola lalandiValenciennes, 1833 (type locality Brazil) should apply only to the species in the Southern Hemisphere.
Mesocosms are an important tool in experimental aquatic ecology, but have been criticized for failing to effectively mimic natural habitats. Identifying contrived features of mesocosms that affect endpoints of interest is a prudent step in ensuring the reliability of mesocosm data. Because anuran larvae actively regulate their exposure to a suite of biotic and abiotic conditions by positioning themselves at various depths in natural ponds, the steep walls and minimal access to shallow regions in common cattle tank mesocosms may force tadpoles into sub-optimal patterns of habitat use. We tested whether adding angled ramps or horizontal platforms to increase access to shallow regions affected survival, time, or mass at metamorphosis of American Toads (Anaxyrus americanus) or Northern Leopard Frogs (Lithobates pipiens) in the presence or absence of Rusty Crayfish (Orconectes rusticus), a common predator that may influence habitat use. Addition of structure had no effect on American Toad survival or metamorphosis, but slightly increased time to metamorphosis and mass at metamorphosis for Northern Leopard Frogs. Behavioral assays revealed that while structure addition increased the number of tadpoles in shallow regions for both species, these increases were small. Most tadpoles were observed on a shallow, built-in lip present on the walls of all of our mesocosms, which are a common feature of most available mesocosms. Post-hoc choice tests revealed that American Toads preferred the lip to both structure types and Northern Leopard Frogs displayed a preference for platforms but no preference when choosing between ramps and the lip. Furthermore, while Rusty Crayfish reduced survival for toads and altered metamorphic responses for both species, they did not alter tadpoles' use of structure. Although access to shallow water may be important for anuran larvae, our study suggests that it may not be necessary to augment shallow water access in cattle tank mesocosms if a shallow lip is already present.
Acanthocobitis was created by Peters in 1861 for a new species, A. longipinnis, from the Ganges River basin in India and has been treated over the past 150 years as a valid genus or as a synonym of Nemacheilus or Noemacheilus. A large number of names have been proposed for species that are morphologically similar, and presumably closely related, to A. longipinnis, with eight treated in recent publications as valid species (most with poorly understood geographic distributions), and 15 treated as synonyms. The present study examined morphological variation across the range of these forms, and diagnosed and mapped the distributions of valid species. Fifteen species are recognized in Acanthocobitis and the recently recognized Paracanthocobitis, including five newly described species and two removed from synonymy. Acanthocobitis is known from the Ganges and Brahmaputra basins of northern India and Bangladesh. Paracanthocobitis ranges from the Indus basin in Pakistan to the Mekong basin of Cambodia and Laos. A key is provided for identification of species.
Theloderma is a widely distributed yet little-known genus of camouflaged tree frogs found throughout Southeast Asia. One member, T. phrynoderma, known only from the moist evergreen forest of the Karen Hills of Myanmar, is redescribed from two recently collected specimens and examination of type specimens. To date the only information available about T. phrynoderma is Boulenger’s brief 1893 description of two type specimens collected in 1888, and phylogenetic analyses to test its placement among other species of Theloderma is lacking due to an absence of specimens. In the present study, we compared two individuals collected in 2009 and 2010 from the Tanintharyi Nature Reserve to the type specimens of T. phrynoderma and proposed that they are also members of this species. We then used two mitochondrial genes (12S and 16S rRNA) and two nuclear genes (rhodopsin and tyrosinase) to infer the phylogenetic relationship of the putative T. phrynoderma to other members of Rhacophoridae, with a special emphasis on Theloderma. The recently collected individuals are of the same species within Theloderma but distinct from all other DNA sequenced congeners. The species redescription is based on a comparison of the newly found reference specimens with the lectotype and paralectotype. In addition, using a combination of morphological characters we provide a more complete diagnosis. The species is distinct from other congeners by a combination of the following characters: a mid-body size (female 44 mm SVL; male mean 41.3 mm SVL); tympanum diameter to eye diameter (70%); partial webbing between fingers; rugose skin with clumped, white-tipped calcified tubercles throughout the dorsal surface; webbing between fingers; distinct darker brown inverted V-marking between its shoulders; absence of vomerine teeth; and absence of vocal sacs.
The upper Clark Fork River basin of western Montana supports a poorly understood sculpin (Uranidea spp.) fauna that has perplexed ichthyologists and fish ecologists since the late 1800s. During our study, the basin contained three sculpin taxa whose taxonomy was under revision. All three taxa were formerly referred to the genus Cottus but are now treated as Uranidea. Our goal was to improve understanding of the distribution and ecology of two of the taxa. From 2006 to 2009, we sampled 144 reaches in 31 streams and rivers to determine distributions of each taxa across the study area and within streams. We collected habitat data in 2007 and stream temperature data from 2006–2009 to identify correlates of sculpin distributions. In streams where both taxa occurred, Rocky Mountain Sculpin Uranidea sp. cf. bairdii were downstream and Columbia Slimy Sculpin U. sp. cf. cognata were upstream with a syntopic zone in between. Summer stream temperatures strongly influenced sculpin distributions, with mean August 2007 water temperatures increasing in order of reaches characterized as: Columbia Slimy Sculpin-dominated, syntopic, Rocky Mountain Sculpin-dominated, and no sculpin. Columbia Slimy Sculpin occurred in cold tributaries of the Blackfoot, Clark Fork, and Bitterroot rivers and in two coldwater refugia in the mainstem Bitterroot River. In contrast, Rocky Mountain Sculpin occupied warmer downstream segments of many Blackfoot and Clark Fork river tributaries as well as some mainstem reaches of both rivers but were absent from the Bitterroot River drainage. Persistence of the taxa will likely depend, both directly and indirectly, on future water temperatures, and thus, sculpins are appropriate targets for researching and monitoring biological changes resulting from climate change.
A new species of the deep-sea ceratioid anglerfish genus Lasiognathus Regan (family Oneirodidae) is described on the basis of three female specimens collected in the northern Gulf of Mexico. Not especially similar to any of the five previously described members of the genus, the new species is unique in having a cylindrical, internally pigmented, anterior escal appendage and a pair of elongate distal escal appendages. The new species is diagnosed and described, and a revised key to the species of the genus is provided.
The Yellowcheek Darter (Etheostoma moorei) is a rare fish endemic to the Little Red River watershed in the Boston Mountains of northern Arkansas. Remaining populations of this species are geographically isolated and declining, and the species was listed in 2011 as federally endangered. Populations have declined, in part, due to intense seasonal stream drying and inundation of lower reaches by a reservoir. We used a kick seine sampling approach to examine distribution and abundance of Yellowcheek Darter populations in the Middle Fork and South Fork Little Red River. We used presence data to estimate occupancy rates and detection probability and examined relationships between Yellowcheek Darter density and environmental variables. The species was found at five Middle Fork and South Fork sites where it had previously been present in 2003–2004. Occupancy rates were >0.6 but with wide 95% CI, and where the darters occurred, densities were typical of other Ozark darters but highly variable. Detection probability and density were positively related to current velocity. Given that stream drying has become more extreme over the past 30 years and anthropogenic threats have increased, regular monitoring and active management may be required to reduce extinction risk of Yellowcheek Darter populations.
The river drainages of Central Mexico have a high degree of freshwater diversity, and are subsequently a focal point for many freshwater fish conservation studies. The livebearing subfamily Goodeinae (Teleostomi: Goodeidae) is a diverse endemic group, under threat from many anthropogenic factors. Xenotoca eiseni, the Redtail Splitfin, a member of this subfamily, has a fragmented distribution in the western basins of the Pacific Coast including the Ríos Grande de Santiago, Compostela, Ayuquila, Coahuayana, and the endorheic Lago de Magdalena and Etzatlán-San Marcos basins. Previous studies have noted high levels of genetic differentiation between the endorheic Lago de Magdalena and Etzatlán-San Marcos basins and surrounding areas which may be indicative of more taxonomic diversity within X. eiseni than currently recognized. The objectives of this study were to use mitochondrial (cytochrome b) and nuclear (ITS-1) DNA sequences and microsatellite data to assess phylogeography, genetic differentiation, and population structure between and within populations of this species. Analysis of the sequence data resulted in two deeply divergent clades, with a mean nucleotide difference of 2.51% within cytochrome b and 0.88% within ITS-1 between populations in the endorheic Lago de Magdalena and Etzatlán-San Marcos basins and all other locations. Microsatellite data also found significant structuring within these two clades of X. eiseni and identified multiple operational conservation units (OCUs). Each of these units contains a proportion of the total variation within the species and requires conservation attention and protection.