Polymorphic tetranucleotide microsatellite DNA loci from the southern dusky salamander (Desmognathus auriculatus)

We describe polymerase chain reaction (PCR) primers and amplification conditions for seven tetranucleotide microsatellite DNA loci isolated from the southern dusky salamander (Desmognathus auriculatus). Primers were tested on 16 individuals from one population in Aiken County, South Carolina. We detected an average of 6.57 alleles per locus, an observed heterozygosity range of 0.44–0.94, and high polymorphic information contents (mean of 0.68).     

Molecular systematics and phylogeography of the Plethodon elongatus species group: combining phylogenetic and population genetic methods to investigate species history

Plethodon elongatus and P. stormi (Caudata: Plethodontidae) are Pacific Northwest endemic species which occur in northwestern California and southwestern Oregon. Studies on these salamanders have resulted in differing taxonomic conclusions, but the underlying historical hypotheses, at both inter- and intraspecific levels, have never been examined in a molecular framework. Here, representatives of 81 populations from throughout the range of both taxa are sequenced. Portions of three mitochondrial protein-coding genes (cytochrome b, NADH dehydrogenase subunit 4, and ATPase 6) were sequenced. Four haplotype groups with nonoverlapping geographical ranges were recovered in separate and combined analyses of the data. One clade corresponds to the distribution of P. stormi, while the remaining three comprise P. elongatus. Phylogenetic relationships among haplotype groups differ in separate analyses of the genes but converge on a well-supported topology, with P. elongatus and P. stormi as monophyletic sister taxa, in combined Maximum Parsimony and Maximum Likelihood analyses. Population genetic analyses of mismatch distributions and Tajima's D-statistic are consistent with range expansion for the largest clade within P. elongatus, covering the northern two-thirds of the species range. In contrast, the P. stormi haplotype clade and the P. elongatus clade from the southern third of the species range may have been relatively stable. Morphological boundaries between P. elongatus and P. stormi are largely congruent with mitochondrial DNA breaks and continued treatment as sister taxa is supported. Although mitochondrial DNA haplotype groups may reflect historical separation within P. elongatus, genetic barriers are incongruent with intraspecific patterns of morphological variation.     

Macroinvertebrate assemblages in perennial headwater streams of the Coastal Mountain range of Washington,U.S.A.

We studied headwater streams in 4 watersheds of Washington's Coastal Mountain region from June to August 1998 to establish macroinvertebrate reference conditions and describe variation in macroinvertebrate assemblage structure among stream orders and among substrates. Macroinvertebrates were sampled with mesh baskets (30 × 30 cm) filled with equal volumes of wood (1.5 l) and cobble (1.5 l) that were installed into fifteen 1st-order, six 2nd-order, and three 3rd-order streams. Low taxa richness and low macroinvertebrate densities were found in all streams. Crayfish dominated (92.7%) biomass estimates, with shredders dominating the non-crayfish component of the biomass. The importance of shredders declined from 1st- to 3rd-order streams. An abundance of wood and a lack of algae and non-wood based detritus in the 1st-order streams led us to suspect that food webs were wood based. We tested this hypothesis by comparing macroinvertebrate assemblages in substrate baskets filled with equal volumes (3 l) of naturally conditioned (1) wood, (2) cobble, or (3) wood and cobble (1.5 l of each). Macroinvertebrate richness was higher in wood-only and mixed baskets than the cobble-only baskets (p = 0.0118), and macroinvertebrate biomass was higher in mixed than cobble-only baskets (p = 0.044).     

Edge Effects of Gated and Ungated Roads on Terrestrial Salamanders

ABSTRACT Roads through forest habitats reduce the abundance of many animal species. These reductions are often referred to as edge effects and their causes include roadkill, degradation of forest habitat, and changes in biotic interactions. Which of these causes are operating can have important implications for management. Terrestrial salamanders in the southern Appalachians have previously been shown to be subject to edge effects from forest roads that are open to traffic. In this study, I examined edge effects on red-backed salamanders (Plethodon cinereus) along forest roads that were either open or gated to prevent vehicle entry. I also included roads that varied in the width of the gravel surface, the width of the roadside verge, and the magnitude of habitat gradients at the forest edge. I found that ungated roads were associated with consistent edge effects on salamanders, whereas no detectable edge effects were found for gated roads. Road width was as good a predictor of the magnitude of edge effects as was the presence of a gate, though the width of the roadside verge was largely unrelated to the magnitude of edge effects. Gradients in habitat variables (soil moisture, temp, leaf litter thickness) were not closely related to the magnitude of edge effects. These results demonstrate that narrow, gated roads do not typically produce edge effects on terrestrial salamanders of the same magnitude as wider, ungated roads. In addition, the apparent importance of road type or road width and the relative unimportance of habitat characteristics suggest that traffic-related factors may be a substantial contributor to edge effects on terrestrial salamanders. These findings provide some support for the closing of redundant forest roads as a low-cost method for diminishing the negative effects of roads on forest ecosystems.     

Polygyrid land snail phylogeny: external sperm exchange, early North American biogeography, iterative shell evolution

A fresh assessment of reproductive behaviour and anatomy, combined with new allozyme data, results in a phylogenetic hypothesis for the 23 polygyrid genera that differs substantially from previous attempts. Analyses based on this phylogeny suggest that (a) evolutionary transition from internal to external sperm exchange occurred only once in polygyrids, with unusual functional intermediates still extant; (b) polygyrid biogeographic history paralleled that of plethodontid salamanders, with hypothesized vicariance events at about 145, 120, 65 and 40 MA, and, dispersal events at about 55 and 40 MA; and (c) iterative shell evolution occurred despite a phylogenetic constraint on ontogenetic whorl-expansion rate.     

Genetic variation in two widespread species of salamanders,Taricha granulosa and Taricha torosa

Two species of the genus Taricha are widely distributed. T. granulosa ranges from southern Alaska to central California. T. torosa is comprised of two described subspecies, T. t. torosa, which occupies much of the coast ranges of California, and T. t. sierrae, which inhabits the western slopes of the Sierra Nevada Mountains. A starch gel electrophoretic survey for genetic variation at 34 loci in four population samples of T. granulosa and at 40 loci in five population samples of T. torosa reveals differences among these taxa both in amounts of intrapopulational variability and in patterns of geographic variation. Average observed heterozygosity is 9.6%±0.3% in T. granulosa, 3.3%±0.5% in T. t. torosa, and 7.2%±1.2% in T. t. sierrae. Average numbers of alleles per locus and proportions of polymorphic loci are also highest in T. granulosa, intermediate in T. t. sierrae, and lowest in T. t. torosa. Oregon and California granulosa are genetically nearly as different as the subspecies of torosa, but geographic variation is continuous in the former. T. torosa on the other hand is comprised of three distinct gene pools—T. t. sierrae and northern and southern races of T. t. torosa. Strikingly different amounts of intrapopulational genetic variation and patterns of geographic variation may be explained by steadystate species differences, but historical causes may also exist.This work was supported by AEC Research Contract AT(04-3)34 and NSF Grant GB-42246 to F. J. Ayala and by an NIH predoctoral traineeship administered by the Department of Genetics, U.C. Davis.     

Response of Reptiles and Amphibians to Repeated Fuel Reduction Treatments

Abstract: Recent use of prescribed fire and fire surrogates to reduce fuel hazards has spurred interest in their effects on wildlife. Studies of fire in the southern Appalachian Mountains (USA) have documented few effects on reptiles and amphibians. However, these studies were conducted after only one fire and for only a short time (1–3 yr) after the fire. From mid-May to mid-August 2006 and 2007, we used drift fences with pitfall and funnel traps to capture reptiles and amphibians in a control and 3 replicated fuel-reduction treatments: 1) twice-burned (2003 and 2006), 2) mechanical understory cut (2002), and 3) mechanical understory cut (2002) followed by 2 burns (2003 and 2006). We captured fewer salamanders in mechanical + twice-burned treatment areas than in twice-burned and control treatment areas, but we captured more lizards in mechanical + twice-burned treatment areas than in other treatment areas. Higher lizard captures in mechanical + twice-burned treatment areas likely was related to increased ground temperatures and greater thermoregulatory opportunities. Higher and more variable ground temperatures and faster drying of remaining litter and duff may have led to fewer salamander captures in mechanical + twice-burned treatment areas. Our longer term results, after 2 prescribed burns, differ from shorter term results. After one prescribed burn at the same site, eastern fence lizard (Sceloporus undulatus) captures were greater in mechanical + burn treatment areas but salamander captures did not differ among treatment areas. Our results indicate that multiple (≥2) fuel-reduction treatments that decrease canopy cover may benefit lizards but negatively affect salamanders.