Carlos D. Camp

A NEW SPECIES OF BLACK-BELLIED SALAMANDER (GENUS DESMOGNATHUS) FROM THE APPALACHIAN MOUNTAINS OF NORTHERN GEORGIA

We describe a new species of Desmognathus from Union County, Georgia. It closely resembles D. quadramaculatus, but the two are distinguishable by adult size, body proportions, color pattern, and fixed differences at four allozyme loci. The new, smaller species is currently known from two tributaries of the Nottely River and is sympatric with D. quadramaculatus at both sites. The new form is semi-aquatic and utilizes habitats that are similar to those of D. quadramaculatus. Metamorphosis occurs at a smaller size than in D. quadramaculatus, apparently as a result of a shorter larval period. Selection on life history features may have had a role in the origin and divergence of these forms.

Potential Interference Competition between a Patchily Distributed Salamander (Plethodon petraeus) and a Sympatric Congener (Plethodon glutinosus)

Abstract Aggressive interference can be an important expression of competitive interactions within and among species. We studied potential interference between two similar-sized, sympatric species of woodland salamander. The Pigeon Mountain Salamander, Plethodon petraeus, occurs in habitat patches of rocky outcroppings along a restricted area on the eastern flank of Pigeon Mountain in northwestern Georgia. This species is relatively rare in the intervening areas of forest-floor habitat, which is occupied by a similar-sized, potential competitor, the Slimy Salamander (Plethodon glutinosus). Both species exhibited aggression and defended territories against conspecifics and heterospecifics in laboratory-based encounters. Individuals of P. glutinosus were superior in aggressive encounters with individuals of P. petraeus. Coexistence of the two species occurs because habitats are partially exclusive. There is enough habitat overlap, however, to generate possible interspecific competition. We hypothesize that the presence of territorial, aggressive P. glutinosus in areas between habitat patches may influence interpatch dispersal by P. petraeus.

Use of Twilight Zones of Caves by Plethodontid Salamanders

Abstract We studied the use of six caves by metamorphosed plethodontid salamanders from 2000–2005 in the Cumberland Plateau of northwestern Georgia. Nine species were observed, the most abundant being, in descending order, Eurycea lucifuga, Plethodon glutinosus, P. petraeus, and E. longicauda. Eurycea lucifuga and P. glutinosus were the only species observed in all six caves. Salamanders used caves seasonally, and all four species were more abundant within caves during seasons with warm, long days. A parsimonious explanation for the observed seasonal pattern of cave use is that salamanders use both cave and surface habitats, moving into caves to avoid hot, dry conditions on the surface. Eurycea lucifuga was most abundant in low-elevation, cold caves. The abundance of P. glutinosus was positively related to cave dimension and secondarily to wall heterogeneity. Species richness was not randomly distributed among caves, but neither was it consistently related to particular variables. Caves into which salamanders crowd during certain seasons represent ideal situations for the testing of hypotheses related to species interactions, both within and among species.

The Relationship between Breeding by the Gopher Frog, Rana capito (Amphibia: Ranidae) and Rainfall

Abstract Declines in amphibian species have become a worldwide concern. This concern is heightened by predicted global climatic changes that may result in shifts in current patterns of local precipitation. Because of the potential dependence of successful breeding by amphibians on rainfall patterns, we tested the relationship between breeding by the rare gopher frog (Rana capito) and rainfall. We used data collected from long-term (1988–2000) monitoring of breeding activity at two ponds (one ephemeral, one semi-permanent) located in the Lower Coastal Plain of Alabama. Egg-mass counts at both ponds showed a significant positive relationship between reproductive effort and rainfall during the breeding season. Individuals of R. capito disperse for considerable distances across a xeric landscape and wet conditions allow greater access to breeding sites for more distantly dispersed frogs. We did not find a significant trend in the number of egg masses laid over time at the ephemeral pond; however, there was a significant increase in egg masses deposited at the semi-permanent pond during the course of this study. Understanding the importance of environmental variables such as rainfall will hopefully lead to the successful conservation of this and other species of amphibians with similar environmental requirements.

Genetic diversity in a narrowly endemic, recently described dusky salamander, Desmognathus folkertsi, from the southern Appalachian Mountains

To understand patterns of biodiversity and whether populations and species are in decline, the detection and description of cryptic biodiversity are essential. Salamanders are of particular conservation interest because they potentially harbor many undescribed species due to morphological conservatism. The dusky salamanders, genus Desmognathus, are a species-rich group in which morphologically cryptic species are especially common. Using a portion of the mitochondrial genome and amplified fragment length polymorphism (AFLP), we investigated the genetic diversity of the highly endemic, stream-dwelling salamander, Desmognathus folkertsi, across its known range in the Appalachian Mountains. Mitochondrial data revealed three well-supported lineages, one of which consisted of only one specimen; however, AFLP data were not congruent with the mitochondrial data. There was 1.11% uncorrected sequence divergence between the two well-sampled lineages. Desmognathus folkertsi exhibited 4.29% sequence divergence from the closely related D. quadramaculatus. Isolation by distance was found for both the AFLP and mitochondrial data when stream distance, rather than when straight-line (i.e., geographic) distance was used. Although genetic diversity is often partitioned by river drainages in freshwater taxa, we did not observe such a pattern in D. folkertsi. We propose that human-mediated dispersal by bait-bucket release may augment natural gene flow via aquatic dispersal across streams. Because this species was only recently discovered, the full extent of the geographic range is unknown. Therefore, an ecological niche model, using climate variables and the Maxent algorithm, was used to determine whether additional regions may be suitable for the species. The model predicted a small range limited to extreme southwestern North Carolina and extreme northeastern Georgia. We suggest future surveys be focused in these regions.

Sympatric Occurrence of Two Species of the Two-Lined Salamander (Eurycea bislineata) Complex

Abstract Genetic analyses of contact zones between closely related taxa are critical to an understanding of reproductive isolation between species. We evaluated allelic frequencies and external morphology from one such contact zone between two members of the Eurycea bislineata complex (i.e., E. cirrigera and E. wilderae). We found that, within this zone of contact, these presumed species had significantly different frequencies of alleles at three loci. In addition, these sympatric forms were significantly different in lateral mottling pattern, tail color, and length of tail stripe. These morphological patterns were identical to those used to describe the original subspecies E. b. cirrigera and E. b. wilderae. Evidence from this zone of contact supports the hypothesis that these forms are separate species. Moreover, there is evidence of ecological and/or reproductive character displacement among these species when in sympatry.

ECOLOGY AND LIFE HISTORY OF THE PIGEON MOUNTAIN SALAMANDER

Abstract Using previously preserved material, a minimal number of sacrificed specimens, unharmed live individuals, and field observations, we studied the life history and habitat of the Pigeon Mountain salamander (Plethodon petraeus). Individuals of this species are patchily distributed among various habitats including rock outcrops and cave entrances. They were most abundant relative to other species of salamanders where extensive outcrops were associated with cave openings. Females mature at a larger size (mininum of 65 mm SVL) than males (minimum of 56 mm) and grow to a greater maximum size (85 mm for females and 80 mm for males). The minimum age at maturity appears to be three years for males. Our data on testicular variation suggest that mating occurs during late winter and/or spring.

Ecological Interactions between Two Broadly Sympatric, Cryptic Species of Dusky Salamander (Genus Desmognathus)

The competition–predation hypothesis has been widely used for many years to explain the segregation along moisture gradients by species of dusky salamanders (genus Desmognathus) along Appalachian streams. According to this idea, all species originally favored aquatic sites, and large, aggressive species displaced smaller ones to more terrestrial habitats, both ecologically and evolutionarily. We tested this hypothesis by investigating the role of a recently described, previously unsuspected member (D. folkertsi) of this assemblage. This species coexists in widespread sympatry with its larger, cryptic congener, D. quadramaculatus. The competition–predation hypothesis predicts that the smaller D. folkertsi is displaced to more terrestrial habitats by the larger, aggressive D. quadramaculatus. We did not find D. folkertsi farther from water than D. quadramaculatus. However, in streams where they are sympatric, D. folkertsi was more abundant in small tributaries while D. quadramaculatus predominated along the main stem. This pattern is consistent with niche compression associated with interspecific competition. In behavioral trials to test interactions between these two species, neither species from sympatric populations avoided other salamanders or their chemical cues. Salamander–salamander aggression also appeared to be reduced. Each species from allopatric sites avoided other salamanders, regardless of species, and D. quadramaculatus significantly avoided chemical cues of other salamanders. While the general idea of the competition–predation hypothesis held, specific predictions failed. Therefore, we propose the competition–predation hypothesis be modified to account for each species of Desmognathus having a unique fundamental niche that then influences how they interact with sympatric congeners.

Reproductive Life History of Desmognathus folkertsi (Dwarf Black-bellied Salamander)

Abstract An earlier collection of monthly samples of presumed Desmognathus quadramaculatus from Union County, GA, revealed the presence a previously unknown, sympatric, sibling species. This new form was recently described as D. folkertsi. In this paper, we report on the reproductive life history of this new species from data taken during (1) a 14-month period in 1989–90 and (2) late spring of 1998. Adult males and females mature at approximately the same size (57–58 mm snout–vent length [SVL]), and males reach larger mean (72 versus 66 mm SVL) and maximum (81 versus 75 mm SVL) sizes. Metamorphosis apparently takes place at approximately two years of age, and reproductive maturity is reached at four or more years of age in both sexes. If number of lobes in the multi-lobed testis indicates age, as has previously been presumed in adult male Desmognathus, then the paucity of singly-lobed, presumably young male D. folkertsi in both sampling periods suggest a declining population. Relative measures of density, however, indicated that the population at the study site was stable for eight years between collections. Therefore, testis-lobe data do not appear to be valid estimators of age in desmognathines. Clutch size, estimated from the number of developing follicles, averages approximately 40 eggs and is positively related to female body size. Ova take more than a single year in which to develop to oviposition size. This does not mean, however, that females follow a strictly biennial reproductive cycle.

Aspects of the Life History and Ecology of the Coal Skink, Eumeces anthracinus, in Georgia

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