| evaluation of tadpole mouthpart depigmentation as a diagnostic test for infection by batrachochytrium dendrobatidis for four california anurans. | the objective of this study was to evaluate the utility of gross morphologic examination of larval mouthpart defects as a diagnostic screening test to detect batrachochytrium dendrobatidis infection in four california, usa, anuran species. we examined mouthparts of 2,034 tadpoles of bufo boreas, pseudacris regilla, and rana catesbeiana collected in 2003 and 2004 and bufo canorus collected in 2004. data were recorded for three morphologic features: upper toothrows, lower toothrows, and combined j ... | 2007 | 17984265 |
| cattle grazing and conservation of a meadow-dependent amphibian species in the sierra nevada. | world-wide population declines have sharpened concern for amphibian conservation on working landscapes. across the sierra nevada's national forest lands, where almost half of native amphibian species are considered at risk, permitted livestock grazing is a notably controversial agricultural activity. cattle (bos taurus) grazing is thought to degrade the quality, and thus reduce occupancy, of meadow breeding habitat for amphibian species of concern such as the endemic yosemite toad (anaxyrus [ = ... | 2012 | 22558211 |
| mitochondrial dna evolution in the anaxyrus boreas species group. | the anaxyrus boreas species group currently comprises four species in western north america including the broadly distributed a. boreas, and three localized species, anaxyrus nelsoni, anaxyrusexsul and anaxyrus canorus. phylogenetic analyses of the mtdna 12s rdna, cytochrome oxidase i, control region, and restriction sites data, identified three major haplotype clades. the northwest clade (nw) includes both subspecies of a. boreas and divergent minor clades in the middle rocky mountains, coastal ... | 2009 | 18662792 |
| pesticides are involved with population declines of amphibians in the california sierra nevadas. | several species of frogs and toads are in serious decline in the sierra nevada mountains of california. these species include the threatened red-legged frog ( rana aurora ), foothill yellow-legged frog ( r. boylii ), mountain yellow-legged frog ( r. muscosa ), cascades frog ( rana cascadae ), western toad ( bufo boreas ) and yosemite toad ( b. canorus ). for many of these species current distributions are down to 10% of historical ranges. several factors including introduced predators, habitat l ... | 2001 | 12805670 |
| the genetics of amphibian declines: population substructure and molecular differentiation in the yosemite toad, bufo canorus (anura, bufonidae) based on single-strand conformation polymorphism analysis (sscp) and mitochondrial dna sequence data. | we present a comprehensive survey of genetic variation across the range of the narrowly distributed endemic yosemite toad bufo canorus, a declining amphibian restricted to the sierra nevada of california. based on 322 bp of mitochondrial cytochrome b sequence data, we found limited support for the monophyly of b. canorus and its closely related congener b. exsul to the exclusion of the widespread western toad b. boreas. however, b. exsul was always phylogenetically nested within b. canorus, sugg ... | 2000 | 10736023 |
| determining the effects of cattle grazing treatments on yosemite toads (anaxyrus [=bufo] canorus) in montane meadows. | amphibians are experiencing a precipitous global decline, and population stability on public lands with multiple uses is a key concern for managers. in the sierra nevada mountains (california, usa), managers have specifically identified livestock grazing as an activity that may negatively affect yosemite toads due to the potential overlap of grazing with toad habitat. grazing exclusion from yosemite toad breeding and rearing areas and/or entire meadows have been proposed as possible management a ... | 2013 | 24223919 |
| detecting the influence of rare stressors on rare species in yosemite national park using a novel stratified permutation test. | statistical models often use observational data to predict phenomena; however, interpreting model terms to understand their influence can be problematic. this issue poses a challenge in species conservation where setting priorities requires estimating influences of potential stressors using observational data. we present a novel approach for inferring influence of a rare stressor on a rare species by blending predictive models with nonparametric permutation tests. we illustrate the approach with ... | 2015 | 26031755 |
| a network extension of species occupancy models in a patchy environment applied to the yosemite toad (anaxyrus canorus). | a central challenge of conservation biology is using limited data to predict rare species occurrence and identify conservation areas that play a disproportionate role in regional persistence. where species occupy discrete patches in a landscape, such predictions require data about environmental quality of individual patches and the connectivity among high quality patches. we present a novel extension to species occupancy modeling that blends traditional predictions of individual patch environmen ... | 2013 | 23951296 |
| the role of the egg jelly coat in protecting hyla regilla and bufo canorus embryos from ultraviolet b radiation during development. | previous studies have suggested that ultraviolet b (uvb) radiation may play a role in amphibian population declines. some of these studies also indicate that egg hatching success is unaltered in some species of anurans as a result of uvb exposure. it has been proposed that the egg mass jelly provides photoprotection to the developing embryos. | 2002 | 12515350 |
| daily fluctuating temperatures decrease growth and reproduction rate of a lethal amphibian fungal pathogen in culture. | emerging infectious diseases (eids) are contributing to species die-offs worldwide. we can better understand eids by using ecological approaches to study pathogen biology. for example, pathogens are exposed to variable temperatures across daily, seasonal, and annual scales. exposure to temperature fluctuations may reduce pathogen growth and reproduction, which could affect pathogen virulence, transmission, and environmental persistence with implications for disease. we examined the effect of a v ... | 2020 | 32245440 |
| pleistocene glacial cycles drove lineage diversification and fusion in the yosemite toad (anaxyrus canorus). | species endemic to alpine environments can evolve via steep ecological selection gradients between lowland and upland environments. additionally, many alpine environments have faced repeated glacial episodes over the past two million years, fracturing these endemics into isolated populations. in this "glacial pulse" model of alpine diversification, cycles of allopatry and ecologically divergent glacial refugia play a role in generating biodiversity, including novel admixed ("fused") lineages. we ... | 2019 | 31661155 |