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Peter K Ducey - One of the best experts on this subject based on the ideXlab platform.
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can the eastern red backed salamander Plethodon cinereus persist in an acidified landscape
Ecosphere, 2016Co-Authors: Cheryl Bondi, Peter K Ducey, Colin M Beier, Gregory B Lawrence, Scott W BaileyAbstract:Hardwood forests of eastern North America have experienced decades of acidic deposition, leading to soil acidification where base cation supply was insufficient to neutralize acid inputs. Negative impacts of soil acidity on amphibians include disrupted embryonic development, lower growth rates, and habitat loss. However, some amphibians exhibit intraspecific variation in acid tolerance, suggesting the potential for local adaptation in areas where soils are naturally acidic. The eastern red-backed salamander (Plethodon cinereus) is a highly abundant top predator of the northern hardwood forest floor. Early research found that P. cinereus was sensitive to acidic soils, avoiding substrates with pH < 3.8 and experiencing decreased growth rates in acidic habitats. However, recent studies have documented P. cinereus populations in lower pH conditions than previously observed, suggesting some populations may persist in acidic conditions. Here, we evaluated relationships between organic horizon soil pH and P. cinereus abundance, adult health (body size and condition), and microhabitat selection, based on surveys of 34 hardwood forests in northeastern United States that encompass a regional soil pH gradient. We found no associations between soil pH and P. cinereus abundance or health, and observed that this salamander used substrates with pH similar to that available, suggesting that pH does not mediate their fine-scale distributions. The strongest negative predictor of P. cinereus abundance was the presence of dusky salamanders (Desmognathus spp.), which were most abundant in the western Adirondacks. Our results indicate that P. cinereus occupies a wider range of soil pH than has been previously thought, which has implications for their functional role in forest food webs and nutrient cycles in acid-impaired ecosystems. Tolerance of P. cinereus for more acidic habitats, including anthropogenically acidified forests, may be due to local adaptation in reproductively isolated populations and/or generalist life history traits that allow them to exploit a wider resource niche.
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forest floor distribution of northern redback salamanders Plethodon cinereus in relation to canopy gaps first year following selective logging
Forest Ecology and Management, 1998Co-Authors: Michael Messere, Peter K DuceyAbstract:Abstract Timber harvesting may change forest floor habitats to the detriment of salamander populations. Although the impact of clear-cutting has received much attention, the widely-used practice of selective logging (in which individual trees or small groups of trees are removed leaving gaps in the forest canopy) has been incompletely studied. We examined the effects of such logging on the distributions of individual redback salamanders, Plethodon cinereus , in a mixed deciduous forest that had been harvested 1 yr earlier. Salamander densities and distributions were assessed using thorough searches of leaf litter and cover objects in quadrats along transects which passed from gaps into the surrounding forest. Comparisons were made between quadrats in three location categories: inside the gaps, along gap edges, and within the forest. We found much variation in salamander numbers among transects, but detected no significant differences in the densities of salamanders among the three location categories. Similarly, salamanders did not show different degrees of within-quadrat grouping among the location categories. These results suggest that the newly formed gaps produced by selective logging did not strongly affect the distributions of P. cinereus in the first year following harvest.
Paul R Cabe - One of the best experts on this subject based on the ideXlab platform.
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female philopatry and male biased dispersal in a direct developing salamander Plethodon cinereus
Molecular Ecology, 2011Co-Authors: Eric B Liebgold, Edmund D Brodie, Paul R CabeAbstract:The local resource competition hypothesis and the local mate competition hypothesis were developed based on avian and mammalian systems to explain sex-biased dispersal. Most avian species show a female bias in dispersal, ostensibly due to resource defence, and most mammals show a male bias, ostensibly due to male-male competition. These findings confound phylogeny with mating strategy; little is known about sex-biased dispersal in other taxa. Resource defence and male-male competition are both intense in Plethodon cinereus, a direct-developing salamander, so we tested whether sex-biased dispersal in this amphibian is consistent with the local resource competition hypothesis (female-biased) or the local mate competition hypothesis (male-biased). Using fine-scale genetic spatial autocorrelation analyses, we found that females were philopatric, showing significant positive genetic structure in the shortest distance classes, with stronger patterns apparent when only territorial females were tested. Males showed no spatial genetic structure over the shortest distances. Mark-recapture observations of P. cinereus over 5 years were consistent with the genetic data: males dispersed farther than females during natal dispersal and 44% of females were recaptured within 1 m of their juvenile locations. We conclude that, in this population of a direct-developing amphibian, females are philopatric and dispersal is male-biased, consistent with the local mate competition hypothesis.
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effects of roads on patterns of genetic differentiation in red backed salamanders Plethodon cinereus
Conservation Genetics, 2008Co-Authors: David M Marsh, Robert B Page, Teresa J Hanlon, Rachael Corritone, David E Seifert, Elizabeth C Little, Paul R CabeAbstract:Roads can fragment animal populations by reducing gene flow, which can lead to drift and the loss of genetic diversity. One of the principle signatures of reduced gene flow is increased genetic differentiation in isolated populations, and evidence that roads contribute to such differentiation has been reported for several species. We used microsatellites to examine whether six roads led to increased genetic differentiation in red-backed salamanders (Plethodon cinereus). These six roads included one divided interstate highway, one undivided four-lane highway, and four secondary roads. We found that the genetic distance between plots that were bisected by the interstate highway was significantly greater than the genetic distance between equidistant plots on the same side of the highway. However, for the five smaller roads, plots across the road were no more genetically distinct than were plots on the same side of the road. Bayesian clustering methods also supported both of these findings. The optimal clustering of plots for the interstate highway consisted of two clusters that corresponded to the two sides of highway. For the other five sites, the optimal grouping consisted of a single cluster containing all of the plots. Our findings suggest that gene flow across very large roads is rare and that bisected red-backed salamander populations are likely to diverge from one another. For smaller roads, our results imply that the indirect effects of roads on genetic population structure are probably less of a pressing concern for terrestrial salamanders than are the direct effects of mortality and habitat alteration.
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ecological and genetic evidence that low order streams inhibit dispersal by red backed salamanders Plethodon cinereus
Canadian Journal of Zoology, 2007Co-Authors: David M Marsh, Robert B Page, Teresa J Hanlon, Halin Bareke, Rachael Corritone, Nathan Jetter, Noelle G Beckman, Katherine Gardner, David E Seifert, Paul R CabeAbstract:While many studies have examined the barrier effects of large rivers on animal dispersal and gene flow, few studies have considered the barrier effects of small streams. We used displacement experiments and analyses of genetic population structure to examine the effects of first-order and second-order streams on the dispersal of terrestrial red-backed salamanders, Plethodon cinereus (Green, 1818). We marked red-backed salamanders from near the edges of one first-order stream and one second-order stream, and experimentally displaced them either across the stream or an equal distance far- ther into the forest. A comparison of return rates indicated that both streams were partial barriers to salamander movement, reducing return rates by approximately 50%. Analysis of six microsatellite loci from paired plots on the same side and on opposite sides of the second-order stream suggested that the stream did contribute to genetic differentiation of salamander populations. Collectively, our results imply that low-order streams do influence patterns of movement and gene flow in red-backed salamanders. We suggest that given the high density of first-order and second-order streams in most land- scapes, these features may have important effects on species that, like red-backed salamanders, have limited dispersal and large geographic ranges. Resume´ : Alors que de nombreux travaux ont examinel'effet de barriere des grandes rivieres sur la dispersion et le flux genique chez les animaux, peu d'etudes se sont interessees aux effets de barriere produits par les petits cours d'eau. Nous avons utilisedes experiences de deplacement et des analyses de structure genetique de population pour determiner les ef- fets de cours d'eau d'ordres 1 et 2 sur la dispersion de la salamandre rayee, Plethodon cinereus (Green, 1818), un amphib- ien terrestre. Nous avons marquedes salamandres rayees recoltees pres des berges d'un cours d'eau d'ordre 1 et d'un autre d'ordre 2 et les avons deplacees experimentalement ou bien sur la berge opposee ou alors a une distance equivalente vers l'interieur de la foret. Une comparaison des taux de retour indique que les deux cours d'eau constituent des barrieres partielles au deplacement des salamandres, ce qui reduit les taux de retour de l'ordre de 50 %. L'analyse de six locus mi- crosatellites dans des parcelles appariees sur la meme berge ou alors sur des berges opposees du cours d'eau d'ordre 2 in- dique que le cours d'eau contribue ala differentiation genetique des populations de salamandres. Dans leur ensemble, nos resultats laissent croire que les cours d'eau d'ordres inferieurs influencent les patrons de deplacement et le flux genique chez la salamandre rayee. Nous croyons qu'etant donnela forte densitede cours d'eau d'ordres 1 et 2 dans la plupart des paysages, ces structures peuvent avoir un important effet sur les especes qui, al'instar des salamandres rayees, ont une dis- persion reduite et une aire de repartition etendue. (Traduit par la Redaction)
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fine scale population differentiation and gene flow in a terrestrial salamander Plethodon cinereus living in continuous habitat
Heredity, 2007Co-Authors: Paul R Cabe, Robert B Page, Teresa J Hanlon, Mary E Aldrich, Lisa M Connors, David M MarshAbstract:Several recent studies have shown that amphibian populations may exhibit high genetic subdivision in areas with recent fragmentation and urban development. Less is known about the potential for genetic differentiation in continuous habitats. We studied genetic differentiation of red-backed salamanders (Plethodon cinereus) across a 2-km transect through continuous forest in Virginia, USA. Mark-recapture studies suggest very little dispersal for this species, whereas homing experiments and post-Pleistocene range expansion both suggest greater dispersal abilities. We used six microsatellite loci to examine genetic population structure and differentiation between eight subpopulations of redbacked salamanders at distances from 200 m to 2 km. We also used several methods to extrapolate dispersal frequencies and test for sex-biased dispersal. We found small, but detectable differentiation among populations, even at distances as small as 200 m. Differentiation was closely correlated with distance and both Mantel tests and assignment tests were consistent with an isolation-by-distance model for the population. Extrapolations of intergenerational variance in spatial position (s 2 o15 m 2 ) and pair-wise dispersal frequencies (4Nmo25 for plots separated by 300 m) both suggest limited gene flow. Additionally, tests for sex-biased dispersal imply that dispersal frequency is similarly low for both sexes. We suggest that these low levels of gene flow and the infrequent dispersal observed in markrecapture studies may be reconciled with homing ability and range expansion if dispersing animals rarely succeed in breeding in saturated habitats, if dispersal is flexible depending on the availability of habitat, or if dispersal frequency varies across the geographic range of red-backed salamanders.
Ryan Kerney - One of the best experts on this subject based on the ideXlab platform.
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early limb patterning in the direct developing salamander Plethodon cinereus revealed by sox9 and col2a1
Evolution & Development, 2018Co-Authors: Ryan Kerney, James Hanken, David C BlackburnAbstract:Direct-developing amphibians form limbs during early embryonic stages, as opposed to the later, often postembryonic limb formation of metamorphosing species. Limb patterning is dramatically altered in direct-developing frogs, but little attention has been given to direct-developing salamanders. We use expression patterns of two genes, sox9 and col2a1, to assess skeletal patterning during embryonic limb development in the direct-developing salamander Plethodon cinereus. Limb patterning in P. cinereus partially resembles that described in other urodele species, with early formation of digit II and a generally anterior-to-posterior formation of preaxial digits. Unlike other salamanders described to date, differentiation of preaxial zeugopodial cartilages (radius/tibia) is not accelerated in relation to the postaxial cartilages, and there is no early differentiation of autopodial elements in relation to more proximal cartilages. Instead, digit II forms in continuity with the ulnar/fibular arch. This amniote-like connectivity to the first digit that forms may be a consequence of the embryonic formation of limbs in this direct-developing species. Additionally, and contrary to recent models of amphibian digit identity, there is no evidence of vestigial digits. This is the first account of gene expression in a Plethodontid salamander and only the second published account of embryonic limb patterning in a direct-developing salamander species.
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do larval traits re evolve evidence from the embryogenesis of a direct developing salamander Plethodon cinereus
Evolution, 2012Co-Authors: Ryan Kerney, David C Blackburn, Hendrick Muller, James HankenAbstract:Recent molecular phylogenies suggest the surprising reacquisition of posthatching metamorphosis within an otherwise direct-developing clade of lungless salamanders (family Plethodontidae). Metamorphosis was long regarded as plesiomorphic for Plethodontids, yet the genus Desmognathus, which primarily includes metamorphosing species, is now nested within a much larger clade of direct-developing species. The extent to which the putative reacquisition of metamorphosis in Desmognathus represents a true evolutionary reversal is contingent upon the extent to which both larva-specific features and metamorphosis were actually lost during the evolution of direct development. In this study we analyze development of the hyobranchial skeleton, which is dramatically remodeled during salamander metamorphosis, in the direct-developing red-backed salamander, Plethodon cinereus. We find dramatic remodeling of the hyobranchial skeleton during embryogenesis in P. cinereus and the transient appearance of larva-specific cartilages. Hyobranchial development in this direct-developing Plethodontid is highly similar to that in metamorphosing Plethodontids (e.g., Desmognathus). The proposed reacquisition of hyobranchial metamorphosis within Desmognathus does not represent the "re-evolution" of a lost phenotype, but instead the elaboration of an existing developmental sequence.
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embryonic staging table for a direct developing salamander Plethodon cinereus Plethodontidae
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2011Co-Authors: Ryan KerneyAbstract:This work presents a refined staging table for the direct-developing red-backed salamander Plethodon cinereus, which is based on the incomplete staging system of James Norman Dent (J Morphol 1942; 71:577-601). This common species from eastern North America is a member of the species-rich lungless salamander family Plethodontidae. The staging table presented here covers several stages omitted by Dent and reveals novel developmental features of P. cinereus embryos. These include putative Leydig cells and open gill clefts, which are found in larvae of metamorphosing species but were previously reported as absent in direct-developing Plethodon. Other features found in larvae of metamorphosing salamander species, such as the palatopterygoid bone and lateral line neuromasts, were not observed in this material. The occurrence of larval and metamorphic features in these embryos has direct bearing on the patterns of life history evolution within the Plethodontidae family. This study emphasizes the degree to which typically larval structures are retained in this direct-developing species and provides a staging table for further investigations into the development and evolution of Plethodontid salamanders.
James Hanken - One of the best experts on this subject based on the ideXlab platform.
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early limb patterning in the direct developing salamander Plethodon cinereus revealed by sox9 and col2a1
Evolution & Development, 2018Co-Authors: Ryan Kerney, James Hanken, David C BlackburnAbstract:Direct-developing amphibians form limbs during early embryonic stages, as opposed to the later, often postembryonic limb formation of metamorphosing species. Limb patterning is dramatically altered in direct-developing frogs, but little attention has been given to direct-developing salamanders. We use expression patterns of two genes, sox9 and col2a1, to assess skeletal patterning during embryonic limb development in the direct-developing salamander Plethodon cinereus. Limb patterning in P. cinereus partially resembles that described in other urodele species, with early formation of digit II and a generally anterior-to-posterior formation of preaxial digits. Unlike other salamanders described to date, differentiation of preaxial zeugopodial cartilages (radius/tibia) is not accelerated in relation to the postaxial cartilages, and there is no early differentiation of autopodial elements in relation to more proximal cartilages. Instead, digit II forms in continuity with the ulnar/fibular arch. This amniote-like connectivity to the first digit that forms may be a consequence of the embryonic formation of limbs in this direct-developing species. Additionally, and contrary to recent models of amphibian digit identity, there is no evidence of vestigial digits. This is the first account of gene expression in a Plethodontid salamander and only the second published account of embryonic limb patterning in a direct-developing salamander species.
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do larval traits re evolve evidence from the embryogenesis of a direct developing salamander Plethodon cinereus
Evolution, 2012Co-Authors: Ryan Kerney, David C Blackburn, Hendrick Muller, James HankenAbstract:Recent molecular phylogenies suggest the surprising reacquisition of posthatching metamorphosis within an otherwise direct-developing clade of lungless salamanders (family Plethodontidae). Metamorphosis was long regarded as plesiomorphic for Plethodontids, yet the genus Desmognathus, which primarily includes metamorphosing species, is now nested within a much larger clade of direct-developing species. The extent to which the putative reacquisition of metamorphosis in Desmognathus represents a true evolutionary reversal is contingent upon the extent to which both larva-specific features and metamorphosis were actually lost during the evolution of direct development. In this study we analyze development of the hyobranchial skeleton, which is dramatically remodeled during salamander metamorphosis, in the direct-developing red-backed salamander, Plethodon cinereus. We find dramatic remodeling of the hyobranchial skeleton during embryogenesis in P. cinereus and the transient appearance of larva-specific cartilages. Hyobranchial development in this direct-developing Plethodontid is highly similar to that in metamorphosing Plethodontids (e.g., Desmognathus). The proposed reacquisition of hyobranchial metamorphosis within Desmognathus does not represent the "re-evolution" of a lost phenotype, but instead the elaboration of an existing developmental sequence.
David C Blackburn - One of the best experts on this subject based on the ideXlab platform.
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early limb patterning in the direct developing salamander Plethodon cinereus revealed by sox9 and col2a1
Evolution & Development, 2018Co-Authors: Ryan Kerney, James Hanken, David C BlackburnAbstract:Direct-developing amphibians form limbs during early embryonic stages, as opposed to the later, often postembryonic limb formation of metamorphosing species. Limb patterning is dramatically altered in direct-developing frogs, but little attention has been given to direct-developing salamanders. We use expression patterns of two genes, sox9 and col2a1, to assess skeletal patterning during embryonic limb development in the direct-developing salamander Plethodon cinereus. Limb patterning in P. cinereus partially resembles that described in other urodele species, with early formation of digit II and a generally anterior-to-posterior formation of preaxial digits. Unlike other salamanders described to date, differentiation of preaxial zeugopodial cartilages (radius/tibia) is not accelerated in relation to the postaxial cartilages, and there is no early differentiation of autopodial elements in relation to more proximal cartilages. Instead, digit II forms in continuity with the ulnar/fibular arch. This amniote-like connectivity to the first digit that forms may be a consequence of the embryonic formation of limbs in this direct-developing species. Additionally, and contrary to recent models of amphibian digit identity, there is no evidence of vestigial digits. This is the first account of gene expression in a Plethodontid salamander and only the second published account of embryonic limb patterning in a direct-developing salamander species.
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do larval traits re evolve evidence from the embryogenesis of a direct developing salamander Plethodon cinereus
Evolution, 2012Co-Authors: Ryan Kerney, David C Blackburn, Hendrick Muller, James HankenAbstract:Recent molecular phylogenies suggest the surprising reacquisition of posthatching metamorphosis within an otherwise direct-developing clade of lungless salamanders (family Plethodontidae). Metamorphosis was long regarded as plesiomorphic for Plethodontids, yet the genus Desmognathus, which primarily includes metamorphosing species, is now nested within a much larger clade of direct-developing species. The extent to which the putative reacquisition of metamorphosis in Desmognathus represents a true evolutionary reversal is contingent upon the extent to which both larva-specific features and metamorphosis were actually lost during the evolution of direct development. In this study we analyze development of the hyobranchial skeleton, which is dramatically remodeled during salamander metamorphosis, in the direct-developing red-backed salamander, Plethodon cinereus. We find dramatic remodeling of the hyobranchial skeleton during embryogenesis in P. cinereus and the transient appearance of larva-specific cartilages. Hyobranchial development in this direct-developing Plethodontid is highly similar to that in metamorphosing Plethodontids (e.g., Desmognathus). The proposed reacquisition of hyobranchial metamorphosis within Desmognathus does not represent the "re-evolution" of a lost phenotype, but instead the elaboration of an existing developmental sequence.