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Divergence is often ephemeral, and populations that diverge in response to regional topographic and climatic factors may not remain reproductively isolated when they come into secondary contact. We investigated the geographical structure and evolutionary history of population divergence within Sceloporus occidentalis (western fence lizard), a habitat generalist with a broad distribution that spans the major biogeographical regions of Western North America. We used double digest RAD sequencing to infer population structure, phylogeny and demography. Population genetic structure is hierarchical and geographically structured with evidence for gene flow between biogeographical regions. Consistent with the isolation-expansion model of divergence during Quaternary glacial-interglacial cycles, gene flow and secondary contact are supported as important processes explaining the demographic histories of populations. Although populations may have diverged as they spread northward in a ring-like manner around the Sierra Nevada and southern Cascade Ranges, there is strong evidence for gene flow among populations at the northern terminus of the ring. We propose the concept of an "ephemeral ring species" and contrast S. occidentalis with the classic North American ring species, Ensatina eschscholtzii. Contrary to expectations of lower genetic diversity at northern latitudes following post-Quaternary-glaciation expansion, the ephemeral nature of divergence in S. occidentalis has produced centres of high genetic diversity for different reasons in the south (long-term stability) vs. the north (secondary contact).

Plethodontid salamanders inhabit terrestrial, scansorial, arboreal, and troglodytic habitats in which clinging and climbing allow them access to additional food and shelter as well as escape from unfavorable temperature and moisture conditions and ground-dwelling predators. Although salamanders lack claws and toe pads found on other taxa, they successfully cling to and climb on inclined, vertical, and inverted substrates in nature. Maximum cling angle was tested on smooth acrylic, and the relationship between cling angle, body mass, and surface area of attachment (contact area) was investigated. This study found that many salamander species can cling fully inverted using only a portion of their ventral surface area to attach. Salamanders fall into three functional groups based on mass and maximum cling angle: (1) high performing, very small salamanders, (2) moderately high performing small and medium-sized salamanders, and (3) low performing large salamanders. They show significant differences in maximum cling angle, even between species of similar mass. In species of similar mass experiencing significantly different detachment stress (resulting from significantly different contact area), differences in morphology or behavior affect how much body surface is attached to the substrate. High performance in some species, such as Desmognathus quadramaculatus, is attributable to large contact area; low performance in a similarly sized species, Ensatina eschscholtzii, is due to behavior which negatively impacts contact area. There was not clear evidence of scaling of adhesive strength with increasing body size. Salamander maximum cling angle is the result of morphology and behavior impacting the detachment stresses experienced during clinging.

Understanding how natural and anthropogenic disturbances affect sensitive species is critical to support conservation programs as land use activities and climatic conditions change. Forest management provides a range of ecosystem services to expanding human populations including production of substantial amounts of woody biomass, thereby reducing area under management and increasing opportunity for conservation designations. However, relatively little experimental information is available to describe how manipulating habitat at multiple scales may affect spatial and temporal variation in populations of climate-sensitive forest taxa. We conducted a Before-After Control-Impact experiment over seven years to evaluate responses of two species of Plethodontid salamanders in operational treatment (harvest, replanting, and herbicide application) and control units, Oregon, USA. In addition, we capitalized on existing variation in downed wood size and accounted for potential behavioral responses to evaluate the thermal refugia hypothesis. For Oregon slender salamanders (Batrachoseps wrighti), mean plot-level occupancy (90% CRI) was increased an estimated 11% (1.11; 0.62–2.1) and estimated mean abundance reduced 16% (0.84; 0.54–1.4) post-harvest. For Ensatina (Ensatina eschscholtzii), mean occupancy was reduced an estimated 80% (0.20; 0.08–0.47) and estimated mean abundance reduced 63% (0.37; 0.22–0.65) post-harvest. We found strong evidence of positive associations for both species with downed wood amount. As predicted, we found ambient temperatures to be higher in harvest than control units. Also, internal downed wood temperatures were warmer in harvested units, suggesting these structures may not have provided adequate thermal refugia. Application of an experimental framework provided evidence about both stand and structure level responses to active management. Habitat structures did not appear to buffer against substantial variation in local climate but evidence was equivocal about importance of these structures to population retention. Monitoring of recruitment and retention of downed wood through subsequent rotations can provide critical information to reduce trade-offs between wood production and conservation of climate sensitive taxa.

We examined responses of the woodland salamander Ensatina ( Ensatina eschscholtzii ) to commercial thinning by helicopter in late-seral Douglas-fir forest in northwestern California, USA, using a before-after control-impact (BACI) design. We employed passive pitfall traps on eight (four each treatment and control) 100 trap grids over eight years (1996–2003), three years pre- and five years post-treatment. We conducted 3–11 weekly site visits within each of 10 trap periods depending upon weather over two spring and eight fall periods for a total of 50 visits to test for differences in surface counts and body condition. We standardized data to captures/1000 trap nights. Surface counts over the eight years were highly variable with less surface activity in spring compared to fall. Although the BACI design allows for initial differences among pre-treatment grids there were none. However, in the three years post-treatment (1999–2001) mean counts on treatment grids were significantly lower than on control grids. By 2002 and 2003, post-treatment counts on control and treatment grids both declined substantially, such that despite 47% more salamanders on control grids, variability was sufficient to preclude statistical significance. Recapture rates averaged 23.3% for three years pre-treatment, but increased to 51.4% for the five years post-treatment. Pre-treatment population estimates increased on control grids post-treatment, however, surface density estimates declined. On treatment grids both population and density estimates declined following treatment. Body condition analyses indicated no significant differences between controls and treatments for either sex prior to or post-treatment. The three years of significant differences in surface counts between controls and treatments post-treatment, followed by no differences in the last two years of the study, combined with no differences in BCIs, lead us to conclude that the surface activity of Ensatina on treatments grids was only temporarily impacted by the thinning. Declining population estimates on treatment grids also indicated at least a temporary reduction in those populations. We unexpectedly found declines in counts and density estimates on both sets of grids over the eight years, suggesting a wider effect may be causing reductions in the surface activity of these salamanders, and possibly in their populations.

Intensively-managed forest (IMF) ecosystems support environmental processes, retain biodiversity and reduce pressure to extract wood products from other forests, but may affect species, such as plethodontid salamanders, that are associated with closed canopies and possess limited vagility. We describe: (1) critical aspects of IMF ecosystems; (2) effectiveness of plethodontid salamanders as barometers of forest change; (3) two case studies of relationships between salamanders and coarse woody debris (CWD); and (4) research needs for effective management of salamanders in IMF ecosystems. Although plethodontid salamanders are sensitive to microclimate changes, their role as ecological indicators rarely have been evaluated quantitatively. Our case studies of CWD and salamanders in western and eastern forests demonstrated effects of species, region and spatial scale on the existence and strength of relationships between plethodontid species and a “critical” microhabitat variable. Oregon slender salamanders (Batrachoseps wrighti) were more strongly associated with abundance of CWD in managed second growth forests than ensatina salamanders (Ensatina eschscholtzii). Similarly, CWD was not an important predictor of abundance of Appalachian salamanders in managed hardwood forest. Gaining knowledge of salamanders in IMF ecosystems is critical to reconciling ecological and economic objectives of intensive forest management, but faces challenges in design and implementation.

Woodland (Plethodontid) salamanders occur in huge numbers in healthy forests in North America where the abundances of many species vary along successional gradients. Their high numbers and trophic role as predators on shredder and decomposer arthropods influence nutrient and carbon pathways at the leaf litter/soil interface. Their extreme niche conservatism and low vagility offer further advantages to the use of these salamanders as metrics of forest ecosystem condition. Mill Creek is a 103 km2 commercially logged redwood forest watershed acquired as parkland where original primary forest is being restored. This study evaluated woodland salamanders as metrics of seral recovery at Mill Creek. Surface counts and body condition were examined in four sets of stands, two early seral, one mature, and one of primary forest (never harvested old-growth). Later seral sites were closer to the coast where fog increased available moisture; younger sites were further inland at higher elevations where fog was reduced. We distinguished the effects of geography and succession using ANCOVA with a PCA-derived landscape covariate. Both geography and succession increased counts of California Slender Salamanders (Batrachoseps attenuatus); advancing succession alone indicated increased counts of Ensatina (Ensatina eschscholtzii). Means and variances in body condition of these two species were lower in older stands; for the Del Norte salamander (Plethodon elongatus) only the means were lower. Coastal proximity increased mean body condition in E. eschscholtzii, but with P. elongatus it was the opposite. We modeled surface counts and body condition along environmental gradients associated with succession. The counts and body condition in two of three species when taken together suggested that the increased structural complexity in late-seral forest stands supported larger populations that appeared to be competing for limited resources and, thus, likely have greater population fitness than those in younger forests. B. attenuatus and E. eschscholtzii proved to be viable metrics of advancing succession with their numbers and body condition providing readily quantifiable measures of ecosystem recovery at Mill Creek.

Resident microbial communities living on amphibian skin can have significant effects on host health, yet the basic ecology of the host-microbiome relationship of many amphibian taxa is poorly understood. We characterized intraspecific variation in the skin microbiome of the salamander Ensatina eschscholtzii xanthoptica, a subspecies composed of four genetically distinct populations distributed throughout the San Francisco Bay Area and the Sierra Nevada mountains in California, USA. We found that salamanders from four geographically and genetically isolated populations harbor similar skin microbial communities, which are dominated by a common core set of bacterial taxa. Additionally, within a population, the skin microbiome does not appear to differ significantly between salamanders of different ages or sexes. In all cases, the salamander skin microbiomes were significantly different from those of the surrounding terrestrial environment. These results suggest that the relationship between E. e. xanthoptica salamanders and their resident skin microbiomes is conserved, possibly indicating a stable mutualism between the host and microbiome.

© 2016 by the American Society of Ichthyologists and Herpetologists. Ring species are widely recognized as one of the best natural illustrations of species formation. A ring species is a circular arrangement of populations with one boundary characterized by reproductive isolation, but intergradation among populations elsewhere. They form when populations disperse around a central barrier and form a secondary contact characterized by reproductive isolation. Ring species are often presented as a taxonomic conundrum, because the presence of a single boundary exhibiting reproductive isolation leaves the ring of populations uncomfortably situated between one and two species. Here we review the ring species concept, with a focus on the salamander Ensatina eschscholtzii and the Greenish Warbler, Phylloscopus trochiloides. We argue that ring species demonstrate the gradual nature of species formation, and thereby illustrate the model of species formation originally put forth by Darwin. We also argue that ring species have become overly idealized, with a focus on strict criteria to the detriment of evolutionary lessons. Like all models of evolutionary change, the ring species concept is an oversimplification, and an ideal ring species has never been found. Finally, we review ring species in light of the general lineage concept of species, and argue that ring species status, while nicely accommodated by recognizing a single species, is independent of taxonomy. The essential features of a ring species are a biogeographic history resulting in a ring-like distribution, and the presence of a single species border characterized by reproductive isolation. Under the general lineage concept, reproductive isolation is a contingent, but not necessary, property of evolutionary lineages. Whether one considers a ring species complex to be one species or many does not change the evolutionary message, and the problems (and lessons) presented by ring species do not go away with taxonomic changes.

In certain regions of Canada and the United States, amphibians have been shown to be sensitive to forest management and the short-term adverse effects of timber harvesting on terrestrial amphibians have been well documented in the literature. However, the effects of silvicultural treatments on amphibians may not be realized until many years after treatment. Manipulative forest management experiments with pre- and post-treatment data, random assignment of replicates to treatments, and analyses over a large spatial scale are rare in the literature. Furthermore, even studies with pre- and post-treatment data can be affected by ecological time lags; the longevity of some species may mean that it could take several years to observe a treatment effect. Riparian areas in forested landscapes of the Pacific Northwest have been recognized for high species richness of amphibians yet little is known about the persistence of amphibians in mature forest fragments such as unharvested riparian buffers surrounded by clearcuts. Our study investigated the efficacy, 2 and 10 years post-logging, of two different riparian management zone prescriptions established around third- and fourth-order streams in western Washington to mitigate the effects of upland timber harvest on amphibians. Our findings suggest that there is no global response by terrestrial amphibians to logging or to the retention of riparian management zones. Rather, species showed individual responses that varied over time and between treatments and transects. Specifically Coastal Tailed Frogs (Ascaphus truei) declined in clearcut upland habitats 2- and 10-years following logging while Western Red-backed Salamander (Plethodon vehiculum) and Ensatina (Ensatina eschscholtzii) appear to benefit from the recommended riparian management zone width. The influence of site effects was evident for some species, whereas for others there is some suggestion of treatment effects, but the analyses were confounded by patterns of natural population change at both local and regional scales, which were evident 2 years following logging. Our results exemplify the need for longer-term studies to ensure that potentially confounding factors, such as natural population fluctuation, are considered when interpreting the results of time series data.

Analysis of late Pleistocene fossils recovered from near the Huntington Beach, California (USA), pier (site LACM 7679) has revealed a diverse fauna dating to approximately 40 14C ka BP. Extinct megafauna (three genera) are present; however, a microfauna including three genera of fish, five genera of amphibians, twelve genera of reptiles, two genera of birds, and ten genera of small mammals dominates the assemblage in terms of diversity. Additional identification of seven genera of non-marine mollusks and various macro- and microscopic plant remains including grasses, three families of herbs, and seven genera of trees provides a wealth of information concerning the past ecology of what is currently a coastal dune field complex. During the Rancholabrean Period, the LACM 7679 locality was approximately 10 km inland from the Pleistocene coastline and contained lush riparian zones interspersed with coastal sage scrub, a few trees, and grasslands teeming with a variety of small and large animals.

The salamander Ensatina eschscholtzii Gray is a classic example of a ring species, or a species that has expanded around a central barrier to form a secondary contact characterized by species-level divergence. In the original formulation of the ring species scenario, an explicit biogeographical model was proposed to account for the occurrence of intraspecific sympatry between two subspecies in southern California (the 'southern closure' model). Here we develop an alternative ring species model that is informed by the geomorphological development of the California Coast Ranges, and which situates the point of ring closure in the Monterey Bay region of central coastal California (the 'Monterey closure' model). Our study has two aims. The first is to use phylogenetic methods to evaluate the two competing biogeographical models. The second is to describe patterns of phylogeographical diversity throughout the range of the Ensatina complex, and to compare these patterns with previously published molecular systematic data. Western North America, with a focus on the state of California, USA. We obtained mitochondrial DNA sequence data from 385 individuals from 224 populations. A phylogeny was inferred using Bayesian techniques, and the geographical distributions of haplotypes and clades were mapped. The two biogeographical ring species models were tested against our Bayesian topology, including the associated Bayesian 95% credible set of trees. High levels of phylogeographical diversity were revealed, especially in central coastal and northern California. Our Bayesian topology contradicts the Monterey closure model; however, 0.08% of the trees in our Bayesian 95% credible set are consistent with this model. In contrast, the classic ring species biogeographical model (the southern closure model) is consistent with our Bayesian topology, as were 99.92% of the trees in our 95% credible set. Our Bayesian phylogenetic analysis most strongly supports the classic ring species model, modified to accommodate an improved understanding of the complex geomorphological evolution of the California Coast Ranges. In addition, high levels of phylogeographical diversity in central and northern California were identified, which is consistent with the striking levels of allozymic differentiation reported previously from those regions.

Color patterns commonly vary geographically within species, but it is rare that such variation corresponds with divergent antipredator strategies. The polymorphic salamander Ensatina eschscholtzii, however, may represent such a case. In this species, most subspecies are cryptically colored, whereas E. e. xanthoptica, the Yellow eyed ensatina, is hypothesized to be an aposematic mimic of highly toxic Pacific newts (genus Taricha). To test the mimicry hypothesis, we conducted feeding trials using Western Scrub-Jays, Aphelocoma californica. In every feeding trial, we found that jays, following presentation with the presumed model (T. torosa), were more hesitant to contact the presumed mimic (E. e. xanthoptica) than a control subspecies lacking the postulated aposematic colors (E. e. oregonensis). The median time to contact was 315 sec for the mimic and 52 sec for the control. These results support the mimicry hypothesis, and we suggest that E. e. xanthoptica is likely a Batesian mimic, rather a Mullerian or quasi-Batesian mimic, of Pacific newts.

Amphibian declines have been documented worldwide; however the vast majority are species associated with aquatic habitats. Information on the status and trends of terrestrial amphibians is almost entirely lacking. Here we use data collected across a 12-yr period (sampling from 1984-86 and from 1993-95) to address the question of whether evidence exists for declines among terrestrial amphibians in northwestern California forests. The majority of amphibians, both species and relative numbers, in these forests are direct-developing salamanders of the family Plethodontidae. We examined amphibian richness and evenness, and the relative abundances of the four most common species of plethodontid salamanders. We examined evidence of differences between years in two ecological provinces (coastal and interior) and across young, mature, and late seral forests and with reference to a moisture gradient from xeric to hydric within late seral forests. We found evidence of declines in species richness across years on late seral mesic stands and in the coastal ecological province, but these differences appeared to be caused by differences in the detection of rarer species, rather than evidence of an overall pattern. We also found differences among specific years in numbers of individuals of the most abundant species, Ensatina eschscholtzii, but these differences also failed to reflect a consistent pattern of declines between the two decadal sample periods. Results showing differences in richness, evenness, and relative abundances along both the seral and moisture continua were consistent with previous research. Overall, we found no compelling evidence of a downward trend in terrestrial plethodontid salamanders. We believe that continued monitoring of terrestrial salamander populations is important to understanding mechanisms of population declines in amphibian species.

Low temperature reduces the performance of muscle-powered movements, but in movements powered by elastic-recoil mechanisms, this effect can be mitigated and performance can be increased. To better understand the morphological basis of high performance and thermal robustness of elastically powered movements, we compared feeding dynamics at a range of temperatures (5-25°C) in two species of terrestrial plethodontid salamanders, Plethodon metcalfi and Ensatina eschscholtzii, which differ in tongue muscle architecture and the mechanism of tongue projection. We found that Ensatina is capable of ballistic projection with a mean muscle-mass-specific power of 2100 W kg−1, revealing an elastic mechanism. Plethodon, in contrast, projected its tongue non-ballistically with a mean power of only 18 W kg−1, indicating it is muscle-powered. Ensatina projected the tongue significantly farther than Plethodon and with dynamics that had significantly lower thermal sensitivity at temperatures below 15°C. These performance differences were correlated with morphological differences, namely elongated collagenous aponeuroses in the projector muscle of Ensatina as compared to Plethodon which are likely the site of energy storage, and the absence in Ensatina of projector muscle fibers attaching to the tongue skeleton that allows projection to be truly ballistic. These findings demonstrate that, in these otherwise similar species, the presence in one species of elaborated connective tissue in series with myofibers confers not only 10-fold greater absolute performance but also greater thermal robustness of performance. We conclude that changes in muscle and connective-tissue architecture are sufficient to alter significantly the mechanics, performance and thermal robustness of musculoskeletal systems.

All amphibians are thought to possess two distinct types of dermal gland: mucous and granular. Mucous glands typically produce an acidic, flocculent and carbohydrate positive secretion that keeps skin moist and helps maintain homeostasis. In this study, we use a battery of histochemical tests to identify these traditional mucous glands in the dermis of the plethodontid salamander Ensatina eschscholtzii. The periodic acid-Schiff, alcian blue, toluidine blue and carmine reactions reveal the absence of both acidic glycosaminoglycans and traditional mucous glands. Instead, E. eschscholtzii produces neutral mucus in specialized granular glands, which we name mucus-producing granular glands (MPGGs). The loss of traditional mucous glands is a derived trait for Ensatina. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 469–477.

The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders E. eschscholtzii xanthoptica and E. eschscholtzii platensis hybridize in the central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was resampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (1) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730 m to 2000 m; (2) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over five generations; (3) there were very few if any putative F1s, but a relatively high number of backcrossed individuals in the central portion of transects; and (4) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit showed maximum values near the center of the zones. Using estimates of cline width and dispersal, we infer strong selection against hybrids. This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent selection and reinforces the value of Ensatina as a system for the study of divergence and speciation at multiple stages.

A field experiment was conducted to test the hypothesis that the plethodontid salamander Ensatina eschscholtzii xanthoptica benefits from aposematic coloration. Under field conditions, clay models painted to resemble E. e. xanthoptica were attacked significantly less often than models lacking the supposed aposematic colors. In addition, the head region of models was attacked significantly more frequently than random, suggesting the models were perceived as prey items. These results are consistent with the hypothesis that E. e. xanthoptica is a mimic of highly toxic Pacific Newts in the genus Taricha. The significance of the E. e. xanthoptica phenotype for the ring species biogeographic scenario and future research directions are briefly discussed.

As part of a larger effort to manage rare, forest-associated species on United States Forest Service [USFS] lands, we conducted surveys to examine the terrestrial amphibian fauna in the region north of Shasta Lake in Shasta County, California. Our goal was to assess species diversity of terrestrial amphibians in this area and attempt to identify new localities of the Shasta salamander (Hydromantes shastae). We chose our survey area based on the distribution of USFS lands, the known range of H. shastae, and past survey efforts (Fig. 1). We selected 40 Public Land Survey Sections from USGS 7.5' topographic maps for sampling. Sections within the study area were selected for survey based on the presence of a road or trail that allowed sufficient access for travel to and from the site and for sampling to occur in a single day. In each selected sectionr the largest stream crossing the primary access road or trail was chosen as the initiation point for surveys. Two surveyors searched 5-m wide meandering belts roughly parallel to the stream, 1 that began approximately 5 m and the other approximately 50 m from the stream edge. At the conclusion of 2 h search time or 0.8 km stream length the crew crossed the stream and repeated the procedure working in the opposite direction. An additional 1 person-hour opportunistic search (30 min/surveyor) was conducted in areas adjacent to the transects that the surveyors deemed most likely to harbor terrestrial salamanders. Searches were conducted by turning cover objects such as rocks and down wood. All surveyors had previous experience surveying for terrestrial amphibians. Surveys were conducted from January to March 2002, when air temperatures were between 1 and 19°C and substrates beneath cover objects were moist. Because a main target of our surveys was H. shastae, a known population was visited weekly as a reference site. All H. shasfae captured at newly discovered sites were deposited in the Museum of Vertebrate Zoology, University of California at Berkeley, for use in assays of genetic diversity. All H. shastae captured at the reference site were released at the point of capture. All other captured reptiles and amphibians were identified to species, measured, and released. A map of historic H. shastae sites was compiled from museum collection records (American Museum of Natural History, California Academy of Sciences, Carnegie Museum of Natural History, Field Museum of Natural History, Humboldt State University, Los Angeles County Museum, Louisiana State University Museum of Natural Sciences, Milwaukee Public Museum, Texas Cooperative Wildlife Collection, University of California Berkeley Museum of Vertebrate Zoology, University of Texas Arlington, University of Michigan Museum of Zoology), observational reports from the ShastaTrinity National Forest, and unpublished observations (P Lewendal, Environmental Planner, State of California, Eureka, CA; L Lindstrand III, Fisheries/Wildlife Biologist, North State Resources, Inc., Redding, CA). We combined records that appeared to be from the same locality. If the precision of the observation was not sufficient to differentiate the location of 2 sites, they were considered 1 site. The known site information contains localities ranging from the recent detection of a single individual

Despite the general lack of theoretical or empirical support, biological corridors are assumed to mitigate the detrimental effects of habitat fragmentation by increasing landscape connectivity. To test the hypothesis that mechanisms which affect immigration rates from a source to a target patch are affected by the presence of a corridor in an otherwise unsuitable matrix, we created two strongly contrasting pathways in replicated field experiments. One pathway type included only bare mineral soil, the other included a potential corridor. We conducted these experiments with Ensatina eschscholtzii, a salamander in the family Plethodontidae. Pathways with surface organic material removed provided a harsh environment for E. eschscholtzii, which was reflected by lower selection, shorter residency time, and higher movement rates than on pathways that contained vegetation (corridor pathways). However, the numbers of E. eschscholtzii reaching target patches connected by corridor pathways were greater than those reaching target patches connected by bare pathways only in plots in which the matrix environment seemed most severe. Our results suggest that identifying candidate corridor areas on conservation maps might be difficult because animals may show compensatory behavioral responses to different types of habitat separating source and target patches. We argue that knowledge of a species' habitat-specific dispersal behaviors is critical to reliably designating corridors as functional components of reserve design.

Understanding the biotic consequences of Pleistocene range shifts and fragmentation remains a fundamental goal in historical biogeography and evolutionary biology. Here, we combine species distribution models (SDM) from the present and two late Quaternary time periods with multilocus genetic data (mitochondrial DNA and microsatellites) to evaluate the effect of climate-induced habitat shifts on population genetic structure in the Large-blotched Ensatina (Ensatina eschscholtzii klauberi), a plethodontid salamander endemic to middle and high-elevation conifer forest in the Transverse and Peninsular Ranges of southern California and northern Baja California. A composite SDM representing the range through time predicts two disjunct refugia, one in southern California encompassing the core of the species range and the other in the Sierra San Pedro Martir of northern Baja California at the southern limit of the species range. Based on our spatial model, we would expect a pattern of high connectivity among populations within the northern refugium and, conversely, a pattern of isolation due to long-term persistence of the Sierra San Pedro Martir population. Our genetic results are consistent with these predictions based on the hypothetical refugia in that (i) historical measures of population connectivity among stable areas are correlated with gene flow estimates; and (ii) there is strong geographical structure between separate refugia. These results provide evidence for the role of recent climatic change in shaping patterns of population persistence and connectivity within the Transverse and Peninsular Ranges, an evolutionary hotspot.

We developed 15 new polymorphic microsatellites for the plethodontid salamander Ensatina eschscholtzii. Loci were isolated from a genomic library from Ensatina eschscholtzii xanthoptica enriched for (AAAG)(n) repetitive elements. The number of alleles per locus ranged from 4 to 20 (mean 9) in the sampled population. Observed heterozygosity ranged from 0.37 to 1. None of the loci deviated from Hardy-Weinberg equilibrium or showed significant linkage disequilibrium after a Bonferroni correction for multiple comparisons. All loci amplified in the six other subspecies of the Ensatina eschscholtzii complex. These new markers will prove useful in measuring gene flow and population structure as well as patterns of mating and sperm use in Ensatina.

The salamander Ensatina eschscholtzii is an example of a ring species in which extant intermediate stages of terminal forms have a nearly continuous range, offering replicated interactions at several stages of divergence. We employ a greatly expanded allozyme database and individual-based analyses to separate the effects of divergence time and gene flow to evaluate how gradual divergence of populations around the ring contributes to the development of reproductive isolation. Despite the high degree of genetic (Dor= 0.39) and ecomorphological divergence observed in secondary contacts around the ring, reproductive isolation or rare hybridization is observed only at the terminus of the ring. Instead, in the secondary contacts sampled around the ring, hybrids are common and reproductively successful, enabling genetic leakage between parental genomes and the potential for genetic merger. Nevertheless, genetic admixture is geographically broad (100 km) only in contacts between ecomorphologically similar populations (within subspecies). When divergence is accompanied by alternative patterns of adaptive divergence (between subspecies), zones of intergradation are narrower and affect populations only locally (8 km). Diversification and consequent genetic interactions in Ensatina reveal a continuum between populations, ecological races, and species, where polytypic traits and high genetic differentiation are maintained without reproductive isolation.

The plethodontid salamander species Ensatina eschscholtzii comprises seven subspecies that are geographically distributed in a ring surrounding California's Central Valley. The subspecies are differentiated primarily on the basis of colour pattern, although there is also significant electrophoretic protein variation both within and among subspecies. The subspecies intergrade around the north end of the valley, whereas at the southern end, two morphologically distinct subspecies meet but do not interbreed. Thus, the species is believed to be at or near speciation. The present study examines osteological variation in Ensatina eschscholtzii using x-radiographs of 436 individuals from 19 localities around the ring-shaped range of the species. In marked contrast to the distinct geographic differentiation in colour pattern variation, skeletal conservatism predominates and the small amounts of variation seen in the limbs and vertebral column show no correlation with geography. Thus, skeletal variation does not further elucidate the status of speciation in E. eschscholtii. Rare skeletal variants, especially in the limb, follow patterns of variation that implicate developmental processes in constraining skeletal variability. In the digits, variation in the number of phalanges in E. eschscholtzii is congruent with variation produced by mitotic inhibition experiments in the developing axolotl (Ambystoma mexicanum) limb. In the mesopodium, the sequence of mineralization (in rare large individuals where mineralization occurs) matches the sequence of prechondrogenic condensation in the developing Ambystoma limb. Although constraints on morphological variability by internal developmental mechanisms can account for the patterns of variation seen among these rare limb variants, the question remains open as to whether developmental processes are responsible for the overall skeletal conservatism seen in E. eschscholtzii.

The salamander Ensatina eschscholtzii is a classic example of a ring species, and has an intricate biogeographic history. Within a part of the ring distribution, earlier work using allozymes disclosed high levels of genetic structure in central coastal California, where the subspecies oregonensis, xanthoptica, and eschscholtzii meet. We used mitochondrial cytochrome b sequences to further examine patterns of divergence in this area, including data from 155 localities (309 individuals). Our focus is on the documentation of population-level haplotype lineages. We show that oregonensis is represented by two unrelated, phenotypically similar clades, both of which possess substantial substructure of their own. The subspecies xanthoptica includes two lineages that differ in phenotype, one of which has colonized the foothills of the Sierra Nevada. The subspecies eschscholtzii occurs mainly to the south, but some populations from a northern lineage extend into the Monterey Bay region, where they approach xanthoptica geographically. In sum, populations in the central coastal California region form a distributional patchwork, including three subspecies, three clades (which differ from the three subspecies), and ten haplotype lineages. We conclude that such striking levels of phylogeographic structure reflect interspersed episodes of spatial fragmentation, in part driven by the complex geomorphological evolution of the California Coast Range system.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:21:20Z No. of bitstreams: 0 Made available in DSpace on 2014-05-27T11:21:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-06-01 The analysis of interactions between lineages at varying levels of genetic divergence can provide insights into the process of speciation through the accumulation of incompatible mutations. Ring species, and especially the Ensatina eschscholtzii system exemplify this approach. The plethodontid salamanders E. eschscholtzii xanthoptica and E. eschscholtzii platensis hybridize in the central Sierran foothills of California. We compared the genetic structure across two transects (southern and northern Calaveras Co.), one of which was resampled over 20 years, and examined diagnostic molecular markers (eight allozyme loci and mitochondrial DNA) and a diagnostic quantitative trait (color pattern). Key results across all studies were: (1) cline centers for all markers were coincident and the zones were narrow, with width estimates of 730 m to 2000 m; (2) cline centers at the northern Calaveras transect were coincident between 1981 and 2001, demonstrating repeatability over five generations; (3) there were very few if any putative F1s, but a relatively high number of backcrossed individuals in the central portion of transects: and (4) we found substantial linkage disequilibrium in all three studies and strong heterozygote deficit both in northern Calaveras, in 2001, and southern Calaveras. Both linkage disequilibrium and heterozygote deficit showed maximum values near the center of the zones. Using estimates of cline width and dispersal, we infer strong selection against hybrids. This is sufficient to promote accumulation of differences at loci that are neutral or under divergent selection, but would still allow for introgression of adaptive alleles. The evidence for strong but incomplete isolation across this centrally located contact is consistent with theory suggesting a gradual increase in postzygotic incompatibility between allopatric populations subject to divergent selection and reinforces the value of Ensatina as a system for the study of divergence and speciation at multiple stages. © 2005 The Society for the Study of Evolution. All rights reserved. Museum of Vertebrate Zoology University of California, Berkeley 3101 Valley Life Science Building 3160, Berkeley, CA 94720-3160 Department of Evolutionary Genomics Joint Genome Institute Lawrence Berkeley National Laboratory, 2800 Mitchell Drive, Walnut Creek, CA 94598-1631 Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista, 13506-900 Rio Claro, São Paulo Centre de Biologie et de Gestion des Populations (CBGP/INRA) Campus International de Baillarguet, 34988 Montferrier-sur-Lez Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista, 13506-900 Rio Claro, São Paulo

The closely related salamander genera Plethodon and Aneides (Plethodontidae) differ in morphology, behavior, and ecology. Although the systematics of these taxa has been the focus of much study, many details remain unresolved. To generate an hypothesis for the relationships among these taxa, I sequenced a segment of the mitochondrial protein-coding gene ND4 and portions of mitochondrial tRNAs. Taxa sampled were 5 species of Aneides, 7 species of western Plethodon, and 13 species of eastern Plethodon. Ensatina eschscholtzii was used as the outgroup. Phylogenetic analyses using maximum-parsimony, neighbor-joining, and maximum-likelihood consistently recovered some relationships. The eastern species of Plethodon are a robust, well-supported clade. Sister taxon relationships of P. elongatus and P. stormi, of P. dunni and P. vehiculum, and of A. hardii and the three west coast species of Aneides were also consistently resolved with good support. The monophyly of Aneides was only weakly supported in some analyses and there is no evidence for the monophyly of Plethodon or of the western species of Plethodon. Excluding the relatively distant outgroup, down-weighting saturated substitutions, and analyzing conserved data partitions did not yield additional resolution or support among the lineages of western Plethodon and Aneides. These results are consistent either with saturation of sequences, due to the age of the lineages, or with relatively rapid radiation. An old, rapid radiation is consistent with the results of previous studies. An analysis of current taxonomy within the phylogenetic framework presented here retains Aneides and recognizes Plethodon as a metataxon (indicated with an asterisk, Plethodon*).

Ensatina eschscholtzii is a plethodontid salamander with several geographical races distributed in a ring-like series throughout the coastal mountains and inland Sierra Nevada mountains of California. Populations of these salamanders show genetic and morphological divergence, and in this study, we examined divergence in overt aggressive, passive aggressive/exploratory, avoidance and sensory behaviours in four populations. Two of the populations represent a zone of secondary contact between coastal and inland lineages of Ensatina. We recorded behaviour of resident salamanders paired with same-sex intruders during the non-courtship season. The residents' behaviour was aVected independently by the population of the resident and the population of the intruder but not by the interaction between the resident population and the intruder population. Levels of agonistic and sensory behaviour showed a high degree of constraint among the populations. These behaviours also showed divergence among coastal and inland populations, and the geographical variation in behaviour is consistent with the phylogenetic history of Ensatina. Convergent evolution of behaviour appears to have occurred at the zone of secondary contact between the coastal and inland lineages. Variation in agonistic and sensory behaviour among the populations observed and between the sexes suggests that there may be geographical and sexual variation in territoriality or competition. ? 1998 The Association for the Study of Animal Behaviour Geographical variation among closely related populations provides some of the strongest evidence for the role of natural variation in the evolution of species. This link between geographi- cal variation and evolution within a species is especially apparent in ring species, in which intergradation occurs freely between adjacent populations, but those at the terminal ends of the ring do not interbreed and behave as separate species (Mayr 1963). Levels of intergradation may vary throughout the entire ring, resulting in geographical variation among the subspecies. The geographical variation shown by ring species can be used to address questions such as whether behavioural evolution has occurred among closely related and genetically interconnected popula- tions. Behavioural variation may be associated not only with the evolutionary relationships

The Ensatina eschscholtzii complex of plethodontid salamanders, a well-known “ring species,” is thought to illustrate stages in the speciation process. Early research, based on morphology and coloration, has been extended by the incorporation of studies of protein variation and mitochondrial DNA sequences. The new data show that the complex includes a number of geographically and genetically distinct components that are at or near the species level. The complex is old and apparently has undergone instances of range contraction, isolation, differentiation, and then expansion and secondary contact. While the hypothesis that speciation is retarded by gene flow around the ring is not supported by molecular data, the general biogeographical hypothesis is supported. There is evidence of a north to south range expansion along two axes, with secondary contact and completion of the ring in southern California. Current research targets regions once thought to show primary intergradation, but which molecular markers reveal to be zones of secondary contact. Here emphasis is on the subspecies E. e. xanthoptica , which is involved in four distinct secondary contacts in central California. There is evidence of renewed genetic interactions upon recontact, with greater genetic differentiation within xanthoptica than between it and some of the interacting populations. The complex presents a full array of intermediate conditions between well-marked species and geographically variable populations. Geographically differentiated segments represent a diversity of depths of time of isolation and admixture, reflecting the complicated geomorphological history of California. Ensatina illustrates the continuing difficulty in making taxonomic assignments in complexes studied during species formation.

The hypothesis that salamander prey-capture behavior is highly stereotyped was tested in the plethodontid salamander Ensatina eschscholtzii using high-speed videography and kinematic analysis of feedings on two types of prey (waxworms and termites). The results show that E. eschscholtzii is capable of modulating the timing and magnitude of tongue and jaw movements in response to prey type. Feedings on waxworms, the larger prey, were characterized by shorter durations and higher velocities of tongue and jaw movements compared with feedings on termites, particularly in the latter portion of the feeding sequence (i.e. after prey contact). To test the hypothesis that sensory feedback through the tongue pad plays a role in modulating feeding movements in response to prey type, the ramus lingualis of the glossopharyngeal nerve (cranial nerve IX), which is known to carry sensory information from the tongue pad in salamanders, was transected bilaterally. This experimental deafferentation of the tongue pad had no effect on the degree or direction of differences in feeding kinematics across prey type. These results refute the glossopharyngeal feedback hypothesis, but are consistent with the hypothesis that E. eschscholtzii responds more vigorously to larger prey by assessing prey size visually.

Geographic variation in 23 to 29 protein-encoding genetic loci was examined in 48 populations of the Ensatina complex, a "ring species" distributed around the Central Valley of California. The samples span two critical links in the chain of morphologically distinct units: the transition from the unblotched to blotched color pattern types in the vicinity of Lassen Peak, northeastern California, and a geographic gap in the range of the complex in the San Gabriel Mountains, southern California. A general pattern of isolation by distance with a regular buildup of genetic distance correlated with increases in geographic distance characterizes the populations studied, with the exception of a little-differentiated group of populations in the northern Sierra Nevada; this region is postulated to be a zone of genetic reticulation characterized by relatively high gene flow. An adaptively significant color pattern is thought to have spread into the northern Sierra Nevada from the south, but protein variants have been introduced both from the north and the south. Genetic distances across the San Gabriel Mountain gap match expectations from the pattern of buildup of genetic distance as a function of geographic distance elsewhere in the complex. A phylogenetic analysis of the protein data supports the reticulation hypothesis; whereas the southernmost populations currently do constitute a monophyletic assemblage, an "extinction experiment" demonstrates that the distinction could be the result of the recent extinction of populations in a present gap in our sampling. The Ensatina complex appears to be a dynamic entity representing several stages in the evolution of species. It is a ring species, and whereas various taxonomic arrangements are possible, no taxonomic changes are proposed.

Background Comparative analyses between amphibians, concentrating on the cellular mechanisms of morphogenesis, reveal a large variability in the early developmental processes that were thought to be conserved during evolution. Increased egg size is one factor that could have a strong effect on early developmental processes such as cleavage pattern and gastrulation. Salamanders of the family Plethodontidae are particularly appropriate for such comparative studies because the species have eggs of varying size, including very large yolky eggs. Results In this paper, we describe for the first time the early development (from fertilization through neurulation) of the plethodontid salamander Ensatina eschscholtzii. This species has one of the largest eggs known for an amphibian, with a mean ± SD diameter of 6 ± 0.43 mm (range 5.3-6.9; n = 17 eggs). Cleavage is meroblastic until approximately the 16-cell stage (fourth or fifth cleavage). At the beginning of gastrulation, the blastocoel roof is one cell thick, and the dorsal lip of the blastopore forms below the equator of the embryo. The ventral lip of the blastopore forms closer to the vegetal pole, and relatively little involution occurs during gastrulation. Cell migration is visible through the transparent blastocoel roof of the gastrula. At the end of gastrulation, a small archenteron spreading dorsally from the blastopore represents the relatively small and superficial area of the egg where early embryonic axis formation occurs. The resulting pattern is similar to the embryonic disk described for one species of anuran. Conclusions Comparisons with the early development of other species of amphibians suggest that an evolutionary increase in egg size can result in predictable changes in the patterns and rate of early development, but mainly within an evolutionary lineage.

The Northwest Forest Plan is a large-scale ecosystem management plan that establishes a system of federal reserves interspersed with matrix forestlands where timber and other commodity production are given priority. Generally, management on reserved lands attempts to protect species associated with older forests. Whereas management in matrix lands emphasizes timber production, it maintains some protections for species associated with older forests. We conducted surveys at randomly selected points within the range of the Scott Bar Salamander (Plethodon asupak) and the southern portion of the range of the Siskiyou Mountains Salamander (P. stormi). We conducted surveys on both reserved and matrix lands to assess the relative role that these allocations play in the long-term persistence of Plethodon salamanders in this region. At low elevations (

We sampled terrestrial salamanders in riparian and upland areas within a 40-y-old managed forest site in western Oregon. We found 303 ensatinas (0.015 animals/m2) and 14 nests (0.0007 nests/m2, 0.05 nests/ensatina) within 20,280 m2 of forested habitat surveyed. Clutch size averaged 8.3 eggs (range 3 to 11), comparable to previous reports from Washington but lower than reported for California. Of 14 nests found, 11 were in upland forest, >30 m from streams. Nests were typically on or under downed wood. Limited downed wood recruitment was apparent from decay class distributions. Managed wood recruitment may be necessary in such young stands to maintain critical life history functions of the ensatina and other terrestrial salamanders.

Few studies have been conducted on amphibian communities in managed, second-growth Douglas-fir (Pseudotsuga menziesii) forests in the Pacific Northwest. My objectives were to investigate patterns of amphibian species richness, biomass, and abundance, and explore habitat relationships in different age classes of second-growth Douglas-fir forests managed primarily for timber production. I sampled terrestrial amphibian populations occurring in 4 distinct age classes of managed forest in western Washington with pitfall traps from 1992 to 1994. Although these forests were devoid of residual old growth, and all stands were at least in their second rotation, they contained the same assemblage of amphibian species occurring in unmanaged Douglas-fir forests in this region. Terrestrial amphibian communities in managed forests were structured differently than in unmanaged forests, however, with higher proportions of northwestern salamanders (Ambystoma gracile) and western redback salamanders (Plethodon vehiculum), and a much lower proportion of tailed frogs (Ascaphus truei). Contrary to several previous studies, I found no evidence that variation in amphibian abundances was strongly influenced by the amount of coarse woody debris on the forest floor. Further research is needed to elucidate the effects of intensive timber management on coarse woody debris and its role in the persistence of terrestrial amphibian populations in managed forests. Because rotation-age stands (the oldest age class) had the highest amphibian species richness, total biomass, and total abundance, and contained significantly higher abundances of the ensatina (Ensatina eschscholtzii) and red-legged frog (Rana aurora) than all younger age classes, silvicultural strategies that increase the percentage of rotation-age forest conditions within managed landscapes are likely to enhance the long-term habitat quality of intensively managed forest landscapes for terrestrial amphibians.

Forests managed primarily for wood resources may be lacking in adequate amounts of coarse woody debris (CWD) for forest-floor vertebrates. We assessed associations between captures of forest-floor vertebrates and volume of CWD in IS closed-canopy stands of Douglas-fir (Pseudotsuga menziesii). The volume of CWD ranged from 14 to 859 m 3 /ha. Pitfall traps and timed. area-constrained ground searches were used to capture small mammals and amphibians. The abundance of ensatina (Ensatina eschscholtzii) and clouded salamanders (Aneides ferrens) increased with volume of CWD. In addition, the probability of encountering either ensatina Trowbridge' s shrew (Sorex trowbridgii) increased with cover of CWD on the forest-floor. The average distance from the nearest CWD for amphibians captured during timed, area-constrained ground searches was 0.5 us, versus 1 m between random points and the nearest CWD. Our study suggests that current management guidelines for CWD retention may not provide adequate habitat for forest-floor vertebrates that depend on this component of the habitat.

We sampled amphibians on 3 red alder (Alnus rubra) sites 1 year before and 1 and 2 years after the following treatments were applied to each site: (1) control (uncut), (2) clearcut and broadcast burned, and (3) clearcut, broadcast burned, and then sprayed with the herbicide glyphosate. All sites included uncut riparian buffer strips. For 3 of the 6 species with ≥20 captures in pitfall traps, we did not detect changes in capture rates after clearcutting. Capture rates of ensatinas (Ensatina eschscholtzii) and Pacific giant salamanders (Dicamptodon tenebrosus) decreased after logging. Capture rates of western redback salamanders (Plethodon vehiculum) increased the first year after logging, probably because the salamanders sheltered in pitfalls, but effects on populations were unclear. Logging did not significantly alter capture rates of rough-skin newts (Taricha granulosa), Dunn's salamanders (P. dunni), and red-legged frogs (Rana aurora). Planning the location and timing of clearcuts or other silvicultural practices over a landscape and retaining riparian buffer strips may be necessary to ensure long-term persistence of Pacific giant salamanders. We did not detect any effects of herbicide spraying on capture rates. Capture rates for rough-skin newts and red-legged frogs were higher in uncut red alder stands than in Douglas-fir (Pseudotsuga menziesii) stands sampled in other studies, an indication that, when red alder stands are converted to Douglas-fir, some alders should be left adjacent to streams to provide habitat for these species and other hardwood associates.

Component helminth communities of Aneides lugubris (N = 31), Batrachoseps nigriventris (N = 63), Ensatina eschscholtzii (N = 30), and Taricha torosa (N = 68) from California were determined. The compound helminth community consisted of 1 species of cestode, Bitegmen gerrhonoti and 6 species of nematodes, Batracholandros salamandrae, Cosmocer- coides variabilis, Falcaustra pretiosa, Megalobatrachonema gigantica, Oswaldocruzia pipiens, and Rhabdias joaquinensis. The least diverse infracommunities were associated with Batrachoseps nigriventris while T. torosa had the most diverse fauna. Only B. salamandrae occurred in each of the 4 component communities. Each of the other helminth species was harbored by a single host species. New host records for B. salamandrae in B. nigriventris and T. torosa; 0. pipiens in A. lugubris; C. variabilis in E. eschscholtzii; F. pretiosa and M. gigantica in T. torosa are established.

We used pitfall traps and time-constrained searches to sample amphibians and reptiles and to describe their habitats in oak woodlands at three areas in California. We captured 766 individuals rep- resenting 15 species during pitfall trapping and 333 animals representing 15 species during the time-con- strained searches. A total of 19 species were sampled. Across all study areas, several positive relationships were found between animal abundance and the cover of specific tree species. At Tejon Ranch, two salaman- ders-Batrachoseps nigriventris and Ensatina eschscholtzii croceater-were associated with canyon live oak (Quercus chrysolepis) and two lizards-Sceloporus occidentalis and Eumeces gilberti-were associated with California black oak (Q. kelloggii). At San Joaquin, B. nigriventris was associated with foothill pine (Pinus sabiniana), as was B. attenuatus at Sierra Foothill. Generally, salamanders were found in live oak woodlands on north-facing slopes at Tejon Ranch, or on north-facing woodlands dominated by foothill pine and interior live oak (Q. wislizenii) at Sierra Foothill and San Joaquin. In contrast, lizards used more xeric and open habitats dominated by California black oak, blue oak (Q. douglasii), and valley oak (Q. lobata). As would be expected for terrestrial and fossorial animals, litter depth, the development of grasses and forbs, and cover by downed woody debris and rocks were important in the habitat models. At Sierra Foothill and San Joaquin, these latter variables, in addition to slope, were of primary importance in the habitat models.

Movements and growth in a population of the terrestrial plethodontid salamander Ensatina eschscholtzii platensis were investigated using mark-recapture methods over a period of 1946 days at a mid-elevation site in the central Sierra Nevada of California. The study site included two plots of equal size, totaling 3.0 ha, in an old-growth pine-fir-incense cedar forest. Our sample included 925 captures, and 14% of the animals were recaptured at least once. Males were more active than females; recapture rates were significantly higher for males than for females, despite a 1:1 sex ratio. Variance in distance traveled was significantly greater for males than for females, and most long-range movements were by males, but mean distance traveled did not differ significantly between sexes. The maximum distance moved for males and females was 120.4 m and 60.6 m, respectively. These movement differences between sexes may explain differences in patterns of mtDNA and allozyme variation within the Ensatina species complex. We suggest that terrestrial plethodontids routinely travel distances > 10 m and caution against calculating home-range sizes from studies conducted only on plots of small size.

The ring species Ensatina eschscholtzii (a plethodontid salamander) of western North America has a circle of subspecies surrounding the Central Valley of California which come into contact and are sympatric in southern California. We examined 26 proteins in 19 populations (maximum of 10 specimens per population) collected throughout the range in order to gain an understanding of the degree of differentiation in the group. Allozymic differentiation is profound, with genetic distances in excess of 0.5 (Rogers or Nei) between populations. Naturally hybridizing populations differ by genetic distances greater than 0.4. Two general classes of color morphs, blotched and unblotched, are segregated geographically, but they do not form discrete genetic units. Both are deeply differentiated, and genetic distances among populations of either class exceed those measured between the classes where they are sympatric in southern California. This study disclosed little evidence of gene exchange around the ring of populations and sampling of many additional populations in regions between populations sampled thus far will be required to determine whether smooth intergradation occurs. Although genetic distances measured exceed those between some co-occurring species of plethodontid salamanders, we find no evidence of borders between cryptic species.