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We sampled Eurycea pterophila, typically considered a spring-associated species, from unprecedented depths within Jacob's Well, a natural cave in the Trinity Aquifer. Nearly all of the captures followed high spring-flow events (25–70 cubic feet per second [cfs]), with almost no individuals seen or trapped during low flow (<10 cfs). We analyzed the cytochrome b mitochondrial gene DNA sequences and identified four haplotypes present at Jacob's Well, two of which were unique to the site. However, this variation fit within the range of genetic variation for E. pterophila, indicating there is only one species present. Comparisons with other central Texas species indicate this population is part of the previously reported polytomy referred to as the Eurycea neotenes complex. Because our study had a large sample size from a single locality, we were able to detect discord between our phylogenetic tree, which showed uniformity among individuals from Jacob's Well and nearby populations, and our FST analyses, which showed no migrants among these populations. These observations highlight the need for larger sample sizes to illuminate relationships among central Texas Eurycea populations.
Fossils of Bison (bison) are scarce on the Colorado Plateau, especially in and around the Greater Grand Canyon Region. Because of poor preservation and collection biases in the region, various resource managers have erroneously designated bison a nonnative and human-(re)introduced species. This decision directly impacts an extant herd of approximately 400 bison that periodically meander onto Grand Canyon National Park lands from neighboring U.S. Forest Service and State of Arizona lands. We re-examined and verified paleozoological museum specimens of this large mammal confirming a prehistoric and early historic presence of Bison on the Colorado Plateau. Our findings indicate that Bison bison should be considered a native species on the Colorado Plateau because they have a nearly continuous record of inhabitance in the region. This record is supported by 74 Bison-bearing fossil, subfossil, and historical localities since the latest Pleistocene.
To estimate levels of gene flow over short distances (less than a few kilometers) in the fairy shrimp, Streptocephalus texanus, mitochondrial DNA sequences (part of the cytochrome oxidase locus) were examined in 98 individuals from 13 populations near Moab, Utah. Populations were arranged linearly along two transects on slickrock ridges, and one isolated population about 2–3 km from the others. We found six haplotypes, differing from one another by 1 to 23 nucleotides. Nucleotide diversity among the nine populations from the MiVida ridge was 0.0019 with no isolation by distance. The three populations from the Sand Flat ridge were fixed for the same haplotype, not found in other populations. The isolated population (loop B pool) contained two haplotypes, one of which was very different from others in the study. The general pattern was little differentiation among populations separated by less than about 1 km, with more differentiation at greater distances. This is consistent with passive dispersal of cysts by wind over short distances, and rare long-distance dispersal.
We studied the response of nesting grassland birds occupying short-grass and mixed-grass prairie sites 2 and 3 y following two, large-scale wildfires that burned ≥360,000 ha in the Texas Panhandle in March 2006. Nest success was greater on burned plots compared to unburned plots, though this varied by species and year. Woody vegetation cover was greater around nests on unburned plots compared to burned plots for Cassin's sparrow (Peucaea cassinii) and lark sparrow (Chondestes grammacus). Cassin's sparrows and lark sparrows nested in more-woody vegetation than did grasshopper sparrows (Ammodramus savannarum), and woody vegetation was reduced following the wildfires. The wildfires appear to have had few if any negative influences on the avian community 3 years postfire. This may be due to grassland breeding birds being adapted to landscapes in which, historically, periodic disturbance (e.g., wildfire, intensive grazing by bison [Bison bison]) resulted in vegetation heterogeneity.
During a 2014 aquatic species survey in the Medina River of the San Antonio River Basin of Texas, we located a reproducing population of the state-listed threatened golden orb (Quadrula aurea). In total, 124 live Q. aurea were recovered from a 200 m stretch of the river, and the length, height, and width of all specimens Q. aurea were recorded. Lengths ranged from 10–40 mm, with a mean length of 27 mm. Our findings represent the first modern (since 1970) record of a reproducing population of Q. aurea within the Medina River and indicate that this species could potentially be present in smaller tributaries and rivers throughout its range, and may be more widely distributed than previously thought. This information is significant as this species is currently under review for future federal protections by the United States Fish and Wildlife Service.
Due to the hotter droughts occurring with climate change, grasslands of southwestern deserts and southern plains in the United States are predicted to increasingly lose cover of native plant species, be invaded by nonnative species, and have accelerated soil erosion. We evaluated these predictions for desert grasslands in the Paint Gap Hills of Big Bend National Park, Texas. We used data from 10 monitoring transects established in 1981 and surveyed vegetation composition, canopy cover, and soil surface elevations in 1981, 1983, 1995, and 2014. Four longer and hotter droughts occurred between 1985 and 2014. We found that by 2014 canopy covers of two dominant native warm-season perennial grasses, Bouteloua curtipendula and Bouteloua ramosa, were reduced to near zero, and the cover of many native shrubs and subshrubs had notably declined. By 2014 two nonnative perennial grasses, Eragrostis lehmanniana and Pennisetum ciliare, had invaded, and their expansion could have long-term ecological consequences. Soil surfaces changed from accumulating sediments at a rate of 0.7 mm/year for 1983–1995 to eroding at −1.6 mm/year for 1995–2014. These soil and vegetation changes support predictions of major declines in native desert grasslands and emphasize their vulnerability to climate change.
Noninvasive measures of stress response are used to understand impacts of natural and anthropogenic disturbances on wild animals and can be challenging to interpret without additional contextual information and specifics of the animals in question. We used fecal samples collected from the Henry Mountains American plains bison (Bison bison) herd in Utah to measure the glucocorticoid hormone corticosterone (CORT), a hormone that is indicative of stress. We compared site-specific measures of fecal CORT concentration with measures of covariates related to geography, bison physiology, and human activity to determine whether an unexpected habitat selection pattern could be a response to human disturbance and thus whether ecological covariates could explain variations in fecal CORT concentration in free-ranging bison. No meaningful relationships were found for any of the covariates included in the study, in part due to a scale mismatch between the physiological stress response of bison and the spatiotemporal distribution of fresh feces deposited.
We examined the diets of 43 juveniles of the lizard Uma exsul from Coahuila, Mexico. The diet was composed primarily of adult and larval beetles. The diets of two females collected at the same time and place as the juveniles included beetles as the most important item but hemipterans, ants, and other hymenopterans were also important. Our observations suggest that the differences between the diets of juvenile U. exsul in this study and adult U. exsul in another study likely reflect both local abundances of prey and ontogenetic changes.
We document a nesting female of peregrine falcon (Falco peregrinus) in Austin, Texas. Nesting took place in an artificial nest box installed on the tower at the University of Texas campus. The female produced four infertile eggs. This finding documents the first nesting in Travis County and broadens the range of peregrine falcon in the state.
A western burrowing owl (Athene cunicularia hypugaea) found dead in southern California had many light-colored lesions visible grossly on its liver, and histopathology revealed extensive necrosis throughout the hepatic parenchyma. Single-celled organisms were seen in clear spaces within the areas of necrosis. The owl was diagnosed with protozoal hepatitis.
A juvenile Bothrops asper (Terciopelo) collected in Tamaulipas, Mexico, is identified as the westernmost locality for the species range-wide. We review and map the distribution in Tamaulipas and adjacent areas of San Luis Potosí and Veracruz, Mexico, based on museum and literature records. The specimen was dissected and its stomach contained Cryptotis parva, a novel prey item for the species. We review previous literature reports for specific prey items.
Little is known about black bear (Ursus americanus) populations in northeastern Arizona, an area characterized by rugged canyon topography and varied habitat composition. We placed global positioning system collars on four bears in this area to characterize second-order, landscape-level habitat use and examine habitat use and movement patterns of bears across this landscape. Data from four global positioning system collars revealed that bears use areas with higher tree canopy cover and terrain ruggedness, indicating that forest and escape cover are important factors driving black bear habitat use at the landscape level. Movement patterns revealed long, linear mean daily movements that follow the structure of the canyon topography. These long, linear movements also allow bears to take advantage of the mosaic of habitats and food resources available in this unique landscape.
We report a fifth locality and natural history notes for the Mexican water mouse Rheomys mexicanus. This is the third record for Oaxaca, and it corresponds to the northernmost known locality for the genus Rheomys and for the species R. mexicanus. In addition, it represents the highest elevation known for the species.
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