| several hypothalamic peptides stimulate in vitro thyrotropin secretion by pituitaries of anuran amphibians. | the effects of several hypothalamic peptides on hormone secretion by pituitaries of three species of anuran amphibians were investigated using in vitro techniques. secretion of thyrotropic bioactivity (designated thyrotropin or tsh) was quantified by bioassay of the pituitary incubation medium using thyroxine (t4) production by paired thyroids from the same animals. pituitaries from adult male rana pipiens were cultured in medium alone, 10 or 100 ng/ml thyrotropin-releasing hormone (trh), 1000 n ... | 1988 | 2853681 |
| convergent morphological evolution detected by studying proteins of tree frogs in the hyla eximia species group. | protein studies have uncovered an apparent case of convergent evolution among north american tree frogs. the species hyla eximia and hyla regilla are so similar in external morphology that the "wrightorum" subspecies is assigned by some authorities to h. eximia and by others to h. regilla. yet microcomplement fixation experiments show that "wrightorum" albumin, though virtually indistinguishable from authentic h. eximia albumin, differs as much from h. regilla albumin as from albumins of species ... | 1974 | 4134390 |
| comparative toxicity of guthion and guthion 2s to xenopus laevis and pseudacris regilla tadpoles. | | 1995 | 7749270 |
| developmental responses of amphibians to solar and artificial uvb sources: a comparative study. | many amphibian species, in widely scattered locations, currently show population declines and/or reductions in range, but other amphibian species show no such declines. there is no known single cause for these declines. differential sensitivity to uvb radiation among species might be one contributing factor. we have focused on amphibian eggs, potentially the most uvb-sensitive stage, and compared their resistance to uvb components of sunlight with their levels of photolyase, typically the most i ... | 1996 | 8806225 |
| comparative toxicity of diuron on survival and growth of pacific treefrog, bullfrog, red-legged frog, and african clawed frog embryos and tadpoles. | the effects of the herbicide diuron on survival and growth of pacific treefrog (pseudacris regilla), bullfrog (rana catesbeiana), red-legged frog (rana aurora), and african clawed frog (xenopus laevis) embryos and tadpoles were determined in static-renewal tests. p. regilla and x. laevis embryos had reduced growth and developed increased deformities in diuron concentrations over 20 mg/l. hindlimb bud and forelimb development were retarded in r. aurora following 14 days exposure to diuron concent ... | 1998 | 9543507 |
| comparative effects of ammonium and nitrate compounds on pacific treefrog and african clawed frog embryos. | the effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of pacific treefrog (pseudacris regilla) and african clawed frog (xenopus laevis) embryos were determined in static-renewal tests. the 10-day lc50s for the three ammonium compounds for p. regilla ranged from 25.0-32. 4 mg/l nh4 -n. the 10-day sodium nitrate lc50 for p. regilla was 578. 0 mg/l no3-n. lc50s for x. laevis exposed for 4 or 5 days to the three ammonium compounds ranged from ... | 1999 | 9888966 |
| survival trade-offs between two predator-induced phenotypes in pacific treefrogs (pseudacris regilla). | in many organisms, specific predator species induce defensive phenotypes that are qualitatively different from the phenotypes induced by other predator species. this differential induction implies that there is no optimal phenotype that works best against all predators. however, few studies have actually tested the hypothesis that each predator-induced phenotype provides the highest survival rate in encounters with the predator that induced that phenotype. in this experiment, i reared pacific tr ... | 2006 | 16637360 |
| 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 |
| batrachochytrium dendrobatidis, a novel pathogen approaching endemism in central california. | the recent emergence of amphibian chytridiomycosis has precipitated competing hypotheses regarding the endemic versus novel nature of the causative agent, batrachochytrium dendrobatidis (bd). we conducted a retrospective survey of the california academy of sciences' (san francisco, california, usa) amphibian collection, testing for presence of bd in 4 amphibian species collected from central california between 1897 and 2005. the earliest detection of bd was found in 2 rana catesbeiana in 1961, a ... | 2009 | 19301630 |
| multiple forms of gonadotropin-releasing hormone in amphibian brains. | several forms of gonadotropin-releasing hormone (gnrh)-like molecules were found in brains of both anurans (frogs) and urodeles (salamanders). the presence of the mammalian-like gnrh molecule was confirmed by hplc and cross-reactivity studies. small amounts of salmonid-like gnrh molecules in the brains of frogs (rana pipiens, hyla regilla) and salamanders (taricha granulosa, ambystoma gracile) were detected by comparing the hplc chromatographic pattern and immunological reactivity of the brain e ... | 2012 | 3514371 |
| effects of pesticide mixtures on host-pathogen dynamics of the amphibian chytrid fungus. | anthropogenic and natural stressors often interact to affect organisms. amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. although these factors often co-occur, their effects on amphibians are usually examined in isolation. we hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susc ... | 2015 | 26181492 |
| invasive hybrid tiger salamander genotypes impact native amphibians. | although the ecological consequences of species invasions are well studied, the ecological impacts of genetic introgression through hybridization are less understood. this is particularly true of the impacts of hybridization on "third party" community members not genetically involved in hybridization. we also know little about how direct interactions between hybrid and parental individuals influence fitness. here, we examined the ecological effects of hybridization between the native, threatened ... | 2009 | 19564601 |
| the amphibian skin-associated microbiome across species, space and life history stages. | skin-associated bacteria of amphibians are increasingly recognized for their role in defence against pathogens, yet we have little understanding of their basic ecology. here, we use high-throughput 16s rrna gene sequencing to examine the host and environmental influences on the skin microbiota of the cohabiting amphibian species anaxyrus boreas, pseudacris regilla, taricha torosa and lithobates catesbeianus from the central valley in california. we also studied populations of rana cascadae over ... | 2014 | 24171949 |
| community ecology of invasions: direct and indirect effects of multiple invasive species on aquatic communities. | with many ecosystems now supporting multiple nonnative species from different trophic levels, it can be challenging to disentangle the net effects of invaders within a community context. here, we combined wetland surveys with a mesocosm experiment to examine the individual and combined effects of nonnative fish predators and nonnative bullfrogs on aquatic communities. among 139 wetlands, nonnative fish (bass, sunfish, and mosquitofish) negatively influenced the probability of occupancy of pacifi ... | 2012 | 22834365 |
| survival of three species of anuran metamorphs exposed to uv-b radiation and the pathogenic fungus batrachochytrium dendrobatidis. | when exploring the possible factors contributing to population declines, it is necessary to consider multiple, interacting environmental stressors. here, we investigate the impact of 2 factors, ultraviolet radiation and disease, on the survival of anuran amphibians. exposure to ultraviolet-b (uv-b) radiation increases mortality and results in various sub-lethal effects for many amphibian species. infectious diseases can also negatively impact amphibian populations. in this study, we exposed meta ... | 2006 | 17140139 |
| virulence variation among strains of the emerging infectious fungus batrachochytrium dendrobatidis (bd) in multiple amphibian host species. | emerging infectious diseases have been documented in numerous plant and animal populations. the infectious disease amphibian chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd), is associated with global amphibian population declines. while much bd-amphibian research has centered on response variation in hosts, a paucity of information exists on how variation in the pathogen, such as strain differences, affects infection dynamics. to examine how different bd strains may di ... | 2017 | 28492179 |
| the effect of trematode infection on amphibian limb development and survivorship. | the causes of amphibian deformities and their role in widespread amphibian declines remain conjectural. severe limb abnormalities were induced at high frequencies in pacific treefrogs (hyla regilla) exposed to cercariae of a trematode parasite (ribeiroia sp.). the abnormalities closely matched those observed at field sites, and an increase in parasite density caused an increase in abnormality frequency and a decline in tadpole survivorship. these findings call for further investigation of parasi ... | 1999 | 10221912 |
| an investigation of the alarm response in bufo boreas and rana cascadae tadpoles. | tadpoles of the western toad (bufo boreas) and of the cascades frog (rana cascadae) show an alarm reaction to an extract containing chemical cues from damaged conspecifics. the mean time spent by individual b. boreas tadpoles in the half of the test tank to which the extract solution was added was significantly lower than expected by chance. activity was also significantly greater in bufo extract tests than in control tests. tadpoles did not avoid an extract of another tadpole species (hyla regi ... | 1985 | 3994624 |
| uv repair and resistance to solar uv-b in amphibian eggs: a link to population declines? | the populations of many amphibian species, in widely scattered habitats, appear to be in severe decline; other amphibians show no such declines. there is no known single cause for the declines, but their widespread distribution suggests involvement of global agents--increased uv-b radiation, for example. we addressed the hypothesis that differential sensitivity among species to uv radiation contributes to these population declines. we focused on species-specific differences in the abilities of e ... | 1994 | 8127883 |
| hatching success and pesticide exposures in amphibians living in agricultural habitats of the south okanagan valley, british columbia, canada (2004-2006). | in 2004 to 2006, in the okanagan valley, british columbia, canada, we measured pesticides, water chemistry, and hatching success of great basin spadefoot (spea intermontana), pacific treefrog (pseudacris regilla), western toad (bufo boreas), and columbia spotted frog (rana luteiventris). predator-proof cages containing gosner stage 4 eggs were placed in ponds in nonagricultural reference sites in conventionally sprayed and organic orchards. seventeen pesticides were detected in ponds in sprayed ... | 2010 | 20821610 |
| hypothalamic chromatophore-stimulating activity in the amphibians hyla regilla and ambystoma tigrinum. | | 1967 | 6033857 |
| onset of chromatophore-stimulating activity by the hypothalamus and adenohypophysis in hyla regilla and ambystoma tigrinum. | | 1967 | 6033858 |
| lethal effects of water quality on threatened california salamanders but not on co-occurring hybrid salamanders. | biological invasions and habitat alteration are often detrimental to native species, but their interactions are difficult to predict. interbreeding between native and introduced species generates novel genotypes and phenotypes, and human land use alters habitat structure and chemistry. both invasions and habitat alteration create new biological challenges and opportunities. in the intensively farmed salinas valley, california (u.s.a.), threatened california tiger salamanders (ambystoma californi ... | 2013 | 23140535 |
| parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians. | while often studied in isolation, host-parasite interactions are typically embedded within complex communities. other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (ribeiroia ondatrae) infectio ... | 2012 | 22834364 |
| does timing matter? how priority effects influence the outcome of parasite interactions within hosts. | in nature, hosts are exposed to an assemblage of parasite species that collectively form a complex community within the host. to date, however, our understanding of how within-host-parasite communities assemble and interact remains limited. using a larval amphibian host (pacific chorus frog, pseudacris regilla) and two common trematode parasites (ribeiroia ondatrae and echinostoma trivolvis), we experimentally examined how the sequence of host exposure influenced parasite interactions within hos ... | 2013 | 23754306 |
| experimental infection dynamics: using immunosuppression and in vivo parasite tracking to understand host resistance in an amphibian-trematode system. | although naturally occurring hosts often exhibit pronounced differences in infection and pathology, the relative importance of factors associated with host life history and immunity in explaining such patterns often remains speculative. research in eco-immunology highlights the trade-offs between host physiology and immunity, for which natural variations in disease susceptibility offer a valuable platform to test predictions within this framework. here, we combined use of a novel, in vivo assay ... | 2013 | 23821713 |
| heterogeneous hosts: how variation in host size, behaviour and immunity affects parasite aggregation. | infection heterogeneity is one of the most fundamental patterns in disease ecology, yet surprisingly few studies have experimentally explored its underlying drivers. here, we used large-scale field assessments to evaluate the degree of parasite aggregation within amphibian host populations followed by a novel experimental approach to assess the potential influence of host size, behaviour and immunity in reproducing such heterogeneity. among 227 wetlands, 2468 hosts and seven parasite species, in ... | 2014 | 24548254 |
| three rarely reported digeneans inhabiting amphibians from vancouver island, british columbia, canada. | three rarely reported species of digeneans were collected in amphibian hosts from diversion reservoir, sooke, vancouver island, british columbia, canada. the endangered anuran rana aurora hosted glypthelmins californiensis, gorgoderina multilobata, and megalodiscus microphagus. in addition, the anuran pseudacris regilla and the caudatan taricha granulosa hosted megalodiscus microphagus. gorgoderina multilobata has been reported only once since 1936 and has never been reported outside of californ ... | 2005 | 16419782 |
| a reservoir species for the emerging amphibian pathogen batrachochytrium dendrobatidis thrives in a landscape decimated by disease. | chytridiomycosis, a disease caused by the fungal pathogen batrachochytrium dendrobatidis (bd), is driving amphibian declines and extinctions in protected areas globally. the introduction of invasive reservoir species has been implicated in the spread of bd but does not explain the appearance of the pathogen in remote protected areas. in the high elevation (>1500 m) sierra nevada of california, the native pacific chorus frog, pseudacris regilla, appears unaffected by chytridiomycosis while sympat ... | 2012 | 22428071 |
| higher temperature variability increases the impact of batrachochytrium dendrobatidis and shifts interspecific interactions in tadpole mesocosms. | the emergence of amphibian chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd) has led to the decline and extinction of numerous amphibian species. multiple studies have observed links between climatic factors and amphibian declines apparently caused by bd. using outdoor experimental mesocosms, we tested the response of red-legged frog (rana aurora) tadpoles to increased variation in temperature, a component of climate linked to amphibian declines, and bd exposure. we incl ... | 2012 | 23145331 |
| host identity matters in the amphibian-batrachochytrium dendrobatidis system: fine-scale patterns of variation in responses to a multi-host pathogen. | species composition within ecological assemblages can drive disease dynamics including pathogen invasion, spread, and persistence. in multi-host pathogen systems, interspecific variation in responses to infection creates important context dependency when predicting the outcome of disease. here, we examine the responses of three sympatric host species to a single fungal pathogen, batrachochytrium dendrobatidis, which is associated with worldwide amphibian population declines and extinctions. usin ... | 2013 | 23382904 |
| development and infectious disease in hosts with complex life cycles. | metamorphosis is often characterized by profound changes in morphology and physiology that can affect the dynamics of species interactions. for example, the interaction between a pathogen and its host may differ depending on the life stage of the host or pathogen. one pathogen that infects hosts with complex life cycles is the emerging fungal pathogen of amphibians, batrachochytrium dendrobatidis (bd). we sought to determine how conditions at the larval stage can affect variation in development ... | 2013 | 23565288 |
| the effects of the amphibian chytrid fungus, insecticide exposure, and temperature on larval anuran development and survival. | chytridiomycosis, a disease caused by batrachochytrium dendrobatidis (bd), has been implicated as a cause of amphibian declines. susceptibility may be influenced by environmental factors that suppress the immune response. the authors conducted a laboratory study to examine the effect of temperature, insecticide exposure, and bd exposure during larval anuran development. the authors examined the consequences of exposure to bd, an insecticide (carbaryl or malathion), and static or fluctuating temp ... | 2014 | 25098758 |
| triclosan exposure alters postembryonic development in a pacific tree frog (pseudacris regilla) amphibian metamorphosis assay (treema). | the amphibian metamorphosis assay (ama), developed for xenopus laevis, is designed to identify chemicals that disrupt thyroid hormone (th)-mediated biological processes. we adapted the ama for use on an ecologically-relevant north american species, the pacific tree frog (pseudacris regilla), and applied molecular endpoints to evaluate the effects of the antibacterial agent, triclosan (tcs). premetamorphic (gosner stage 26-28) tadpoles were immersed for 21 days in solvent control, 1.5 μg/l thyrox ... | 2013 | 23159728 |
| contaminant residues and declines of the cascades frog (rana cascadae) in the california cascades, usa. | populations of cascades frogs (rana cascadae) have declined precipitously in the mount lassen area, but remain abundant in the other half of their california range in the klamath mountains. to evaluate the role of contaminants in cascade frog declines, we sampled sediment and frog tadpole tissue at 31 sites where cascades frogs had disappeared and sites where cascades frogs are still present across the lassen and klamath regions. pacific chorus frogs (pseudacris regilla) were tested and used as ... | 2012 | 22639410 |
| citizen scientists monitor a deadly fungus threatening amphibian communities in northern coastal california, usa. | ecoclub youth and supervising family members conducted citizen science to assess regional prevalence and distribution of batrachochytrium dendrobatidis (bd) among amphibians at humboldt bay national wildlife refuge (refuge) and redwood national and state parks (parks), humboldt county, california, us, may 2013 through december 2014. using quantitative real-time pcr, 26 (17%) of 155 samples were positive for bd. positive samples occurred in four frog and toad species: foothill yellow-legged frog ... | 2016 | 27195681 |
| effect of simultaneous amphibian exposure to pesticides and an emerging fungal pathogen, batrachochytrium dendrobatidis. | amphibian declines have been linked to numerous factors, including pesticide use and the fungal pathogen batrachochytrium dendrobatidis (bd). moreover, research has suggested a link between amphibian sensitivity to bd and pesticide exposure. we simultaneously exposed postmetamorphic american toads (anaxyrus americanus), western toads (a. boreas), spring peepers (pseudacris crucifer), pacific treefrogs (p. regilla), leopard frogs (lithobates pipiens), and cascades frogs (rana cascadae) to a facto ... | 2017 | 28001054 |
| effects of environmentally relevant concentrations of endosulfan, azinphosmethyl, and diazinon on great basin spadefoot (spea intermontana) and pacific treefrog (pseudacris regilla). | we conducted dose-response exposures to compare the lethality of endosulfan, diazinon, and azinphosmethyl in the early-life stages of the great basin spadefoot (spea intermontana) and the pacific treefrog (pseudacris regilla). our experiment occurred in two 8-d phases: one, with developing embryos, and two, with gosner stage 27 tadpoles. pesticide concentrations were representative of field-measured concentrations (60 ng/l of endosulfan, 50 ng/l of azinphosmethyl, and 350 ng/l of diazinon), in t ... | 2010 | 20821611 |
| mercury contamination in three species of anuran amphibians from the cache creek watershed, california, usa. | fish and wildlife may bioaccumulate mercury (hg) to levels that adversely affect reproduction, growth, and survival. sources of hg within the cache creek watershed in northern california have been identified, and concentrations of hg in invertebrates and fish have been documented. however, bioaccumulation of hg by amphibians has not been evaluated. in this study, adult and juvenile american bullfrogs (lithobates catesbeianus) and foothill yellow-legged frogs (rana boylii), adult northern pacific ... | 2010 | 19353298 |
| complex interactive effects of water mold, herbicide, and the fungus batrachochytrium dendrobatidis on pacific treefrog hyliola regilla hosts. | infectious diseases pose a serious threat to global biodiversity. however, their ecological impacts are not independent of environmental conditions. for example, the pathogenic fungus batrachochytrium dendrobatidis (bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. we examined the combined ... | 2017 | 28322209 |
| disease and the extended phenotype: parasites control host performance and survival through induced changes in body plan. | by definition, parasites harm their hosts. however, some forms of parasite-induced alterations increase parasite transmission between hosts, such that manipulated hosts can be considered extensions of the parasite's phenotype. while well accepted in principle, surprisingly few studies have quantified how parasite manipulations alter host performance and survival under field and laboratory conditions. | 2011 | 21633498 |
| individual and combined effects of multiple pathogens on pacific treefrogs. | in nature, individual hosts often encounter multiple pathogens simultaneously, which can lead to additive, antagonistic, or synergistic effects on hosts. synergistic effects on infection prevalence or severity could greatly affect host populations. however, ecologists and managers often overlook the influence of pathogen combinations on hosts. this is especially true in amphibian conservation, even though multiple pathogens coexist within amphibian populations, and several pathogens have been im ... | 2011 | 21400194 |
| effects of the pathogenic water mold saprolegnia ferax on survival of amphibian larvae. | infectious diseases are a significant threat to worldwide biodiversity. amphibian declines, a significant part of current biodiversity losses, are in many cases associated with infectious disease. water molds are one group of pathogens affecting amphibians on a worldwide basis. although water molds have been studied extensively for their effects on host embryos, little information is available about how they affect post-embryonic amphibians. we tested the effects of one species of water mold, sa ... | 2009 | 19402452 |
| effects of nitrate and the pathogenic water mold saprolegnia on survival of amphibian larvae. | we tested for a synergism between nitrate and saprolegnia, a pathogenic water mold, using larvae of 3 amphibian species: ambystoma gracile (northwestern salamander), hyla regilla (pacific treefrog) and rana aurora (red-legged frog). each species was tested separately, using a 3 x 2 fully factorial experiment with 3 nitrate treatments (none, low and high) and 2 saprolegnia treatments (saprolegnia and control). survival of h. regilla was not affected significantly by either experimental factor. in ... | 2006 | 16610589 |
| effects of ammonium sulfate on growth of larval northwestern salamanders, red-legged and pacific treefrog tadpoles, and juvenile fathead minnows. | | 2000 | 10656895 |
| impact of guthion on survival and growth of the frog pseudacris regilla and the salamanders ambystoma gracile and ambystoma maculatum. | the effects of the insecticides guthion (technical grade) and guthion 2s (commercial formulation) on survival and growth of tadpoles of the pacific treefrog pseudacris regilla, and larvae of the northwestern salamander ambystoma gracile and the spotted salamander ambystoma maculatum were determined in continuous-flow exposures in the laboratory. ninety-six-hour lc50 values were >3.6 mg/l for p. regilla with technical grade guthion and 1.47 mg/l with the formulation guthion 2s (measured as active ... | 1998 | 9601918 |
| explanation for naturally occurring supernumerary limbs in amphibians. | the occasional occurrence of high frequencies of limb abnormalities, including extra limbs, in natural populations of amphibians has long been a puzzle. in this paper we report the discovery of a population in which such limb abnormalities appear to be caused by a parasitic flatworm (trematode) that uses amphibians as intermediate hosts. the cercarial larval stage of the trematode attacks amphibians, penetrating the skin to form cysts (metacercariae). the cysts are preferentially localized in th ... | 1990 | 2348164 |
| 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 |
| a quantitative genetic test of adaptive decoupling across metamorphosis for locomotor and life-history traits in the pacific tree frog, hyla regilla. | metamorphosis is assumed to be beneficial because it can break developmental links between traits in the different phases of a complex life-cycle and thereby allow larval and adult phases to adapt independently. i tested the prediction that correlations between the larval and adult phases are smaller than within stages. i estimated phenotypic and additive genetic variances and correlations for tadpole swimming speed, frog jump distance, body size, and larval period in a single population of the ... | 2001 | 11580026 |
| avoidance response of juvenile pacific treefrogs to chemical cues of introduced predatory bullfrogs. | bullfrogs (rana catesbeiana), native to eastern north america, were introduced into oregon in the 1930's. bullfrogs are highly efficient predators that are known to eat a variety of prey including other amphibians. in laboratory experiments, we investigated whether juvenile pacific treefrogs (hyla regilla) recognize adult bullfrogs as a predatory threat. the ability of prey animals to acquire recognition of an introduced predator has important implications for survival of the prey. we found that ... | 2001 | 11521404 |
| pesticides and amphibian population declines in california, usa. | several species of anuran amphibians have undergone drastic population declines in the western united states over the last 10 to 15 years. in california, the most severe declines are in the sierra mountains east of the central valley and downwind of the intensely agricultural san joaquin valley. in contrast, coastal and more northern populations across from the less agrarian sacramento valley are stable or declining less precipitously. in this article, we provide evidence that pesticides are ins ... | 2001 | 11434303 |
| the effects of acute and developmental temperature on burst swimming speed and myofibrillar atpase activity in tadpoles of the pacific tree frog, hyla regilla. | the effects of acute and developmental temperature on maximum burst swimming speed, body size, and myofibrillar atpase activity were assessed in tadpoles of the pacific tree frog, hyla regilla. tadpoles from field-collected egg masses were reared in the laboratory at 15 degrees (cool) and 25 degrees c (warm). body size, maximum burst swimming speed from 5 degrees to 35 degrees c, and tail myofibrillar atpase activity at 15 degrees and 25 degrees c were measured at a single developmental stage. b ... | 2006 | 10893175 |
| female choice and plasticity of male calling behaviour in the pacific treefrog. | male pacific treefrogs, hyla regilla, use advertisement and encounter calls to regulate intermale spacing within breeding choruses. when either type of call produced by a neighbour is detected above a particular amplitude, a resident frog responds aggressively by producing encounter calls. these 'aggressive thresholds' differ for the two call types and are plastic: males rapidly resume advertisement calling (accommodate) following repeated presentation of these calls above their aggressive thres ... | 1999 | 10373268 |
| effects of ammonium nitrate, sodium nitrate, and urea on red-legged frogs, pacific treefrogs, and african clawed frogs. | | 1999 | 10475914 |
| pcr primers for microsatellite loci in the anurans rana luteiventris and hyla regilla. | | 1998 | 9711868 |
| genetic comparison of water molds from embryos of amphibians rana cascadae, bufo boreas and pseudacris regilla. | water molds that cause the disease saprolegniasis have been implicated in widespread mortality of amphibian embryos. however, because of the limitations of traditional identification methods, water mold species involved in die-offs or utilized in ecological studies often remain unidentified or identified only as saprolegnia ferax. furthermore, water mold taxonomy requires revision, so very distinct organisms may all be called s. ferax. recent dna-based studies indicate that the diversity of wate ... | 2012 | 22691981 |
| temperature-dependence of auditory nerve response properties in the frog. | response properties of the auditory nerve fibers of the pacific treefrog, hyla regilla, were shown to be comparable to other hylids at a standard temperature of 20 degrees c. this species from a rather variable thermal habitat was compared to the neotropical aboreal species, eleutherodactylus coqui, in a study of auditory responses under conditions of changing temperatures. we found that as temperature increased: the center frequencies (cfs) of tuning curves remained constant for neurons from th ... | 1990 | 2380128 |
| parasite metacommunities: evaluating the roles of host community composition and environmental gradients in structuring symbiont communities within amphibians. | ecologists increasingly report the structures of metacommunities for free-living species, yet far less is known about the composition of symbiont communities through space and time. understanding the drivers of symbiont community patterns has implications ranging from emerging infectious disease to managing host microbiomes. using symbiont communities from amphibian hosts sampled from wetlands of california, usa, we quantified the effects of spatial structure, habitat filtering and host communit ... | 2017 | 28795407 |
| calling at the highway: the spatiotemporal constraint of road noise on pacific chorus frog communication. | loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. the pacific chorus frog (pseudacris regilla) is the most common vocal species of the pacific northwest and can occupy human-dominated habitat types, including agricultural and urban wetlands. this species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. we hypothesiz ... | 2017 | 28070305 |
| effects of nutrient supplementation on host-pathogen dynamics of the amphibian chytrid fungus: a community approach. | anthropogenic stressors may influence hosts and their pathogens directly or may alter host-pathogen dynamics indirectly through interactions with other species. for example, in aquatic ecosystems, eutrophication may be associated with increased or decreased disease risk. conversely, pathogens can influence community structure and function and are increasingly recognised as important members of the ecological communities in which they exist.in outdoor mesocosms, we experimentally manipulated nutr ... | 2016 | 28956554 |
| in situ effects of pesticides on amphibians in the sierra nevada. | for more than 20 years, conservationists have agreed that amphibian populations around the world are declining. results obtained through laboratory or mesocosm studies and measurement of contaminant concentrations in areas experiencing declines have supported a role of contaminants in these declines. the current study examines the effects of contaminant exposure to amphibians in situ in areas actually experiencing declines. early larval pseudacris regilla were translocated among lassen volcanic, ... | 2015 | 25381462 |
| joint toxicity of chlorpyrifos and endosulfan to pacific treefrog (pseudacris regilla) tadpoles. | recent ecotoxicology studies have focused on the potential interaction of pesticides and the effects these interactions may have on aquatic ecosystems. we examined the combined effects of two insecticides, endosulfan and chlorpyrifos, that have been previously examined individually on survival, growth, and development of pacific treefrog (pseudacris regilla) tadpoles. historically, both pesticides have been heavily used in the central valley of california, been identified in downwind montane are ... | 2014 | 25052219 |
| divergent responses of exposed and naive pacific tree frog tadpoles to invasive predatory crayfish. | invasive predators can devastate native species and ecosystems. however, native species may be able to coexist with invasive predators through a variety of mechanisms, such as changes in morphology or behavior due to a plastic response or selection on fixed anti-predator traits. we examined whether exposed and naive populations of pacific tree frog tadpoles (pseudacris regilla) display divergent morphological and behavioral traits in response to the invasive predatory red swamp crayfish (procamb ... | 2014 | 24002711 |
| variations in lethal and sublethal effects of cypermethrin among aquatic stages and species of anuran amphibians. | despite the use of model species to predict the effects of chemicals in the environment, unpredicted variation in levels of risk to organisms from xenobiotics can be observed. physiological and morphological differences between species and life stages may lead to differences in sensitivity, while seasonal and spatial variation in pesticide concentrations may affect the level of risk faced by organisms in the environment. because anurans breed in aquatic habitats subject to contamination by runof ... | 2013 | 23999991 |
| ecomorphology and disease: cryptic effects of parasitism on host habitat use, thermoregulation, and predator avoidance. | parasites can cause dramatic changes in the phenotypes of their hosts, sometimes leading to a higher probability of predation and parasite transmission. because an organism's morphology directly affects its locomotion, even subtle changes in key morphological traits may affect survival and behavior. however, despite the ubiquity of parasites in natural communities, few studies have incorporated parasites into ecomorphological research. here, we evaluated the effects of parasite-induced changes i ... | 2011 | 21608461 |
| beyond immunity: quantifying the effects of host anti-parasite behavior on parasite transmission. | a host's first line of defense in response to the threat of parasitic infection is behavior, yet the efficacy of anti-parasite behaviors in reducing infection are rarely quantified relative to immunological defense mechanisms. larval amphibians developing in aquatic habitats are at risk of infection from a diverse assemblage of pathogens, some of which cause substantial morbidity and mortality, suggesting that behavioral avoidance and resistance could be significant defensive strategies. to quan ... | 2011 | 20857146 |
| toxicity of two insecticides to california, usa, anurans and its relevance to declining amphibian populations. | contaminants have been associated with population declines of several amphibian species in california (usa). pesticides from the central valley of california are transported by winds into the sierra nevada mountains and precipitate into wet meadows where amphibians breed. the present study examined the chronic toxicity of two of the insecticides most commonly used in the central valley and found in the mountains, chlorpyrifos and endosulfan, to larval pacific treefrogs (pseudacris regilla) and f ... | 2009 | 19290680 |
| exposure to tetrabromobisphenol-a alters th-associated gene expression and tadpole metamorphosis in the pacific tree frog pseudacris regilla. | presently in the environment, there exist a number of chemical contaminants which share structural similarity with key naturally occurring regulatory hormones. these hormones play pivotal roles in the normal growth and development of wildlife species and humans. in particular, biphenolic chemical compounds may have the potential to act as agonists or antagonists of thyroid hormone (th) action. we investigated whether there was any biological effect of exposure to low concentrations of the bromin ... | 2006 | 16678281 |
| chance or choice? understanding parasite selection and infection in multi-host communities. | ongoing debate over the relationship between biodiversity and disease risk underscores the need to develop a more mechanistic understanding of how changes in host community composition influence parasite transmission, particularly in complex communities with multiple hosts. a key challenge involves determining how motile parasites select among potential hosts and the degree to which this process shifts with community composition. focusing on interactions between larval amphibians and the pathoge ... | 2019 | 30894285 |
| patterns of clinostomum marginatum infection in fishes and amphibians: integration of field, genetic, and experimental approaches. | digenetic trematodes of the genus clinostomum are cosmopolitan parasites infecting fishes, amphibians, reptiles, and snails as intermediate hosts. despite the broad geographical distribution of this genus, debate about the number of species and how they vary in host use has persisted. to better understand patterns of infection among host species and across life stages, we used large-scale field surveys and molecular tools to examine five species of amphibians and seven species of fishes from 125 ... | 2019 | 30827281 |
| comparative toxicity of ammonium and nitrate compounds to pacific treefrog and african clawed frog tadpoles. | the effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of pacific treefrog (pseudacris regilla [baird and girard]) and african clawed frog (xenopus laevis [daudin]) tadpoles were determined in static-renewal tests. the 10-d ammonium nitrate and ammonium sulfate lc50s for p. regilla were 55.2 and 89.7 mg/l nh4 -n, respectively. the 10-d lc50s for x. laevis for the three ammonium compounds ranged from 45 to 64 μg/l nh4 - n. the 10-d sodium n ... | 1999 | 29857645 |
| phylogeography of pseudacris regilla (anura: hylidae) in western north america, with a proposal for a new taxonomic rearrangement. | the baja california populations of pseudacris regilla, a widespread species in western north america ranging from british columbia to southern baja california, are characterized by extensive geographic fragmentation. we performed phylogeographic and historical demographic analyses on 609 bp of the cytochrome b mitochondrial gene of 110 individuals representing 28 populations to determine the relative influences of current and historical processes in shaping the present distribution of genetic di ... | 2006 | 16627190 |
| serous cutaneous glands of the pacific tree-frog hyla regilla (anura, hylidae): patterns of secretory release induced by nor-epinephrine. | the serous (poison) cutaneous glands of the pacific tree-frog hyla regilla were induced to release their product by 10(-3)m nor-epinephrine stimulation. after discharge structural and ultrastructural features of the cutaneous glands involved in release were observed. furthermore, the discharged product, consisting of discrete, secretory granules, was collected and processed for transmission electron microscope analysis. as indicated by patterns found in the myoepithelium encircling the syncytial ... | 2006 | 16423375 |
| phylogenetic relationships of the north american chorus frogs (pseudacris: hylidae). | we examined phylogenetic relationships of the north american chorus frogs (pseudacris: hylidae) from 38 populations using 2.4 kb of 12s and 16s mtdna to elucidate species relationships and examine congruence of previous phylogenetic hypotheses. parsimony, maximum likelihood, and bayesian phylogenies are consistent and reveal four strongly supported clades within pseudacris: (1). a west coast clade containing regilla and cadaverina, (2). a fat frog clade including ornata, streckeri, and illinoens ... | 2004 | 14715232 |
| the effect of metamorphosis on the repeatability of maximal locomotor performance in the pacific tree frog hyla regilla. | measuring the repeatability of inter-individual differences in locomotor performance is an important first step in elucidating both the functional causes and the ecological consequences of performance variation. thus, repeatability of whole-animal performance traits provides a crucial link between functional and evolutionary biology. in the present study, repeatability of maximal burst locomotor performance was estimated for a single population of the pacific tree frog hyla regilla. animals were ... | 1997 | 9359373 |
| structure and function of the amphibian follicular epithelium during ovulation. | low concentrations of cytochalasin b (ccb) are known to inhibit ovulation in the frog, hyla regilla. examination of amphibian thecal cell ultrastructure reveals filaments (average diameter 71 a) arranged in bundles parallel to the surface of the oocyte. these filaments are often associated with hemidesmosome-like plaques on the basal plasmalemma, while individual filaments appear unaltered morphologically by ccb (1-5 microgram/ml), their organization into bundles, apparent relationship to the he ... | 1977 | 884719 |
| embryonic temperature adaptations of the pacific treefrog, hyla regilla. | | 1975 | 237710 |
| a reappraisal of mating call differentiation in hyla cadaverina (= hyla californiae) and hyla regilla. | | 1971 | 28562936 |
| premating isolating mechanisms in sympatric and allopatric hyla regilla and hyla californiae. | | 1966 | 28562910 |
| neurosecretory processes extending into third ventricle: secretory or sensory? | "dendrites" projecting into the third ventricle from hypothalamic neurosecretory neurons of the pacific tree frog, hyla regilla, appear to be morphologically equipped to serve both secretory and sensory functions. these cell processes contain elementary neurosecretory granules, golgi membranes, mitochondria, and endoplasmic reticulum, suggesting synthesis and possibly release of hormonal material. each "dendrite" is provided with a single cilium which has an accessory centriole and a striated ro ... | 1965 | 14245770 |
| climate warming mediates negative impacts of rapid pond drying for three amphibian species. | anthropogenic climate change will present both opportunities and challenges for pool-breeding amphibians. increased water temperature and accelerated drying may directly affect larval growth, development, and survival, yet the combined effects of these processes on larvae with future climate change remain poorly understood. increased surface temperatures are projected to warm water and decrease water inputs, leading to earlier and faster wetland drying. so it is often assumed that larvae will ex ... | 2014 | 24933805 |
| transcriptome resources for the frogs lithobates clamitans and pseudacris regilla, emphasizing antimicrobial peptides and conserved loci for phylogenetics. | we developed genetic resources for two north american frogs, lithobates clamitans and pseudacris regilla, widespread native amphibians that are potential indicator species of environmental health. for both species, mrna from multiple tissues was sequenced using 454 technology. de novo assemblies with mira3 resulted in 50 238 contigs (n50 = 687 bp) and 48 213 contigs (n50 = 686 bp) for l. clamitans and p. regilla, respectively, after clustering with cd-hit-est and purging contigs below 200 bp. we ... | 2014 | 24028389 |
| accumulation of pesticides in pacific chorus frogs (pseudacris regilla) from california's sierra nevada mountains, usa. | pesticides are receiving increasing attention as potential causes of amphibian declines, acting singly or in combination with other stressors, but limited information is available on the accumulation of current-use pesticides in tissue. the authors examined potential exposure and accumulation of currently used pesticides in pond-breeding frogs (pseudacris regilla) collected from 7 high elevations sites in northern california. all sites sampled are located downwind of california's highly agricult ... | 2013 | 23893497 |
| expression analysis and identification of antimicrobial peptide transcripts from six north american frog species. | frogs secrete antimicrobial peptides onto their skin. we describe an assay to preserve and analyze antimicrobial peptide transcripts from field-collected skin secretions that will complement existing methods for peptide analysis. we collected skin secretions from 4 north american species in the field in california and 2 species in the laboratory. most frogs appeared healthy after release; however, rana boylii in the sierra nevada foothills, but not the coast range, showed signs of morbidity and ... | 2013 | 23759560 |
| influence of water temperature on acetylcholinesterase activity in the pacific tree frog (hyla regilla). | this investigation evaluated whether acetylcholinesterase (ache) in pacific tree frogs (hyla regilla) from different geographical locations was influenced by different temperatures during early aquatic life stages, independent of pesticide exposure. tadpoles were collected from both a california coastal pond and a sierra nevada mountain range pond, usa. groups of frogs from each location were raised in temperatures representative of either the sierra nevada (8 degrees c) or the coastal (19 degre ... | 2005 | 16152981 |
| pulse rise time but not duty cycle affects the temporal selectivity of neurons in the anuran midbrain that prefer slow am rates. | recovery-type auditory neurons in the anuran inferior colliculus (ic) respond with band-pass or low-pass selectivity for sinusoidal am. these cells respond to each modulation cycle at slow am rates and respond only at the onset of fast am or pulse repetition rate (prr) stimuli, failing to recover from the effects of early pulses. this selectivity is not altered by changes in pulse duty cycle. the recovery process is governed therefore by the interpulse interval and not the dimension of the gap b ... | 2005 | 15738274 |
| fixed green and brown color morphs and a novel color-changing morph of the pacific tree frog hyla regilla. | pacific tree frogs hyla regilla are typically either green or brown in dorsal coloration. the frequency of green and brown individuals is known to fluctuate seasonally. previous investigators have generally assumed that the green and brown body colors represent a "fixed" polymorphism and that seasonal changes in the proportion of the two body colors are a consequence of differential survival of the two color morphs. here we report that, in addition to the "fixed" (i.e., non-color-changing) green ... | 2003 | 14582008 |
| polychlorinated biphenyls and toxaphene in pacific tree frog tadpoles (hyla regilla) from the california sierra nevada, usa. | pacific tree frog (hyla regilla) tadpoles were collected throughout the sierra nevada mountain range, california, usa, in 1996 and 1997 and analyzed for the presence of polychlorinated biphenyls (pcbs) and toxaphene. whole-tadpole sigma pcb levels ranged from 244 ng/g (wet wt) at lower elevations on the western slope to 1.6 ng/g high on the eastern slope, whereas sigma toxaphene levels ranged from 15.6 to 1.5 ng/g. linear regression of pcb and toxaphene residue levels versus elevation indicated ... | 2002 | 12371500 |
| fine structure and morphogenic movements in the gastrula of the treefrog, hyla regilla. | the blastoporal groove of the early gastrula of the treefrog, hyla regilla, was examined with the electron microscope. the innermost extension of the groove is lined with invaginating flask- and wedge-shaped cells of entoderm and mesoderm. the distal surfaces of these cells bear microvilli which are underlain with an electron-opaque layer composed of fine granular material and fibrils. the dense layer and masses of vesicles proximal to it fill the necks of the cells. in flask cells bordering the ... | 1965 | 14286299 |
| fine structure of mesodermal and entodermal cells of the blastoporal groove in the treefrog. hyla regilla. | | 1964 | 14335070 |
| color polymorphism in pacific tree frogs. | crosses between green and non-green hyla regilla suggest that green color is determined by genes at two loci; each loci must have a dominant gene. red is the result of a recessive gene and brown a dominant gene. the frequency of frogs with each color varies in different populations. | 1963 | 14068230 |
| changes in lipid bodies during gastrulation in the treefrog, hyla regilla. | | 1963 | 14065141 |
| the hypothalamic neurosecretory system of the tree frog hyla regilla. | | 1957 | 13449175 |
| determination and regulation of polarity in the retina of hyla regilla. | | 1946 | 20341390 |
| there's a frog in my salad! a review of online media coverage for wild vertebrates found in prepackaged produce in the united states. | prepackaged leafy green vegetables represent one of the fastest growing segments of the fresh-produce industry in the united states. several steps in the production process have been mechanized to meet the downstream demand for prebagged lettuces. the growth in this market, however, has come with drawbacks, and chief among them are consumers finding wild animals in prepackaged crops. these incidents may signal an overburdened produce supply chain, but we currently lack the information needed to ... | 2019 | 31022609 |
| disease hotspots or hot species? infection dynamics in multi-host metacommunities controlled by species identity, not source location. | pathogen persistence in host communities is influenced by processes operating at the individual host to landscape-level scale, but isolating the relative contributions of these processes is challenging. we developed theory to partition the influence of host species, habitat patches and landscape connectivity on pathogen persistence within metacommunities of hosts and pathogens. we used this framework to quantify the contributions of host species composition and habitat patch identity on the pers ... | 2020 | 32357383 |
| investigating the potential use of an ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide) as an anti-fungal treatment against the amphibian chytrid fungus, batrachochytrium dendrobatidis. | the disease chytridiomycosis, caused by the pathogenic chytrid fungus, batrachochytrium dendrobatidis (bd), has contributed to global amphibian declines. bd infects the keratinized epidermal tissue in amphibians and causes hyperkeratosis and excessive skin shedding. in individuals of susceptible species, the regulatory function of the amphibian's skin is disrupted resulting in an electrolyte depletion, osmotic imbalance, and eventually death. safe and effective treatments for chytridiomycosis ar ... | 2020 | 32302369 |
| tracking the assembly of nested parasite communities: using β-diversity to understand variation in parasite richness and composition over time and scale. | community composition is driven by a few key assembly processes: ecological selection, drift and dispersal. nested parasite communities represent a powerful study system for understanding the relative importance of these processes and their relationship with biological scale. quantifying β-diversity across scales and over time additionally offers mechanistic insights into the ecological processes shaping the distributions of parasites and therefore infectious disease. to examine factors driving ... | 2020 | 32160311 |
| warming-induced shifts in amphibian phenology and behavior lead to altered predator-prey dynamics. | climate change-induced phenological variation in amphibians can disrupt time-sensitive processes such as breeding, hatching, and metamorphosis, and can consequently alter size-dependent interactions such as predation. temperature can further alter size-dependent, predator-prey relationships through changes in species' behavior. we thus hypothesized that phenological shifts due to climate warming would alter the predator-prey dynamic in a larval amphibian community through changes in body size an ... | 2019 | 30810801 |
| phenological synchrony shapes pathology in host-parasite systems. | a key challenge surrounding ongoing climate shifts is to identify how they alter species interactions, including those between hosts and parasites. because transmission often occurs during critical time windows, shifts in the phenology of either taxa can alter the likelihood of interaction or the resulting pathology. we quantified how phenological synchrony between vulnerable stages of an amphibian host (pseudacris regilla) and infection by a pathogenic trematode (ribeiroia ondatrae) determined ... | 2020 | 31964296 |