Desmognathine Salamanders Research Articles

A peculiar mechanism of bite-force enhancement in lungless salamanders revealed by a new geometric method for modeling muscle moments

Desmognathine salamanders possess unusual morphological features for lungless salamanders that have been proposed to aid in burrowing and biting, including well-ossified jaws and skull and a pair of robust ligaments connecting the atlas to the mandible. We evaluated the function of these and other peculiar desmognathine cranial features in biting by examining the morphology, mechanics and in vivo biting performance of the large Desmognathus quadramaculatus We estimated theoretical biting force using a novel geometric method that we describe. Results provide quantitative evidence to bolster earlier conclusions that the unusual atlanto-mandibular ligaments couple ventral head flexion, a unique desmognathine behavior, with biting performance. Our analysis also reveals that the ligaments not only transmit, but also amplify the force of head flexion when acting together with the unusual stalked occipital condyles, enlarged atlas and massive quadratopectoralis muscles. The geometric model predicts that this mechanism contributes five times the biting force of the three jaw levator muscles combined and predicts that maximum biting force in D. quadramaculatus matches or exceeds forces reported for similarly sized lizards. The in vivo biting performance we measured was several times greater in D. quadramaculatus than another plethodontid salamander, Pseudotriton ruber, which lacks the unusual morphology and mechanism of desmognathines. The effective biting mechanism of D. quadramaculatus we describe is an emergent property of many of the distinguishing morphological features of desmognathine salamanders and likely plays an important role in their natural history given that desmognathines use biting in feeding, defense and even courtship.

Relative Growth Rates in Three Species ofDesmognathus(Amphibia: Plethodontidae)

Abstract: Observed life histories of animals reflect trade-offs among growth, reproduction, and survival that serve to maximize fitness under particular environmental regimes. Body size and age at first reproduction, as expressions of growth and developmental rates, are key trade-off elements. I estimated relative growth rates in three species of desmognathine salamanders that vary markedly in body size and habitat associations. Sampling was conducted in two assemblages of the species in the southern Blue Ridge of North Carolina. The species, ranked from larger to smaller, were Desmognathus quadramaculatus, D. monticola, and D. ocoee. An existing skeletochronological database served as a source of age estimates in salamanders for which standard lengths had been recorded. Body masses were estimated for these individuals from regressions of mass on standard length. Relative growth rates were estimated by the Gompertz model for growth in standard length and body mass, and by the von Bertalanffy model for gr...

Application of the Gompertz Function in Studies of Growth in Dusky Salamanders (Plethodontidae:Desmognathus)

Gompertz growth functions were fitted to skeletochronological data sets of three species of desmognathine salamanders from an assemblage (Wolf Creek) in the Cowee Mountains of southwestern North Carolina. The results were compared to earlier evaluations of growth in desmognathines from a nearby assemblage (Coweeta) in the Nantahala Mountains. In two of the species, Desmognathus quadramaculatus and D. monticola, larger adult body sizes were attained at Coweeta than at Wolf Creek, whereas adult body sizes of the third species, D. ocoee, were similar in the two populations. Growth in both standard length (snout–vent length) and body mass were evaluated. The early phases of growth, prior to sexual maturation, were similar in the larger D. quadramaculatus and the smaller D. monticola, and higher in both species than in the even smaller D. ocoee. In all three species, growth rates tended to be higher in the Coweeta populations than in those at Wolf Creek. The inflexions of the Gompertz curves for body mass vers...

Conservation genetics of extremely isolated urban populations of the northern dusky salamander (Desmognathus fuscus) in New York City

Urbanization is a major cause of amphibian decline. Stream-dwelling plethodontid salamanders are particularly susceptible to urbanization due to declining water quality and hydrological changes, but few studies have examined these taxa in cities. The northern dusky salamander (Desmognathus fuscus) was once common in the New York City metropolitan area, but has substantially declined throughout the region in recent decades. We used five tetranucleotide microsatellite loci to examine population differentiation, genetic variation, and bottlenecks among five remnant urban populations of dusky salamanders in NYC. These genetic measures provide information on isolation, prevalence of inbreeding, long-term prospects for population persistence, and potential for evolutionary responses to future environmental change. All populations were genetically differentiated from each other, and the most isolated populations in Manhattan have maintained very little genetic variation (i.e. <20% heterozygosity). A majority of the populations also exhibited evidence of genetic bottlenecks. These findings contrast with published estimates of high genetic variation within and lack of structure between populations of other desmognathine salamanders sampled over similar or larger spatial scales. Declines in genetic variation likely resulted from population extirpations and the degradation of stream and terrestrial paths for dispersal in NYC. Loss of genetic variability in populations isolated by human development may be an underappreciated cause and/or consequence of the decline of this species in urbanized areas of the northeast USA.

Effect of Caudal Autotomy on Aquatic and Terrestrial Locomotor Performance in Two Desmognathine Salamander Species

Plethodontid salamanders within the genus Desmognathus range from species that are primarily aquatic to species that are fully terrestrial. Thus, these species are a good model system to use for a comparison of the effect of tail loss on maximal swimming and running performance, and propensity for caudal autotomy in closely related species that primarily inhabit either aquatic or terrestrial environments. I examined the effect of caudal autotomy on maximal swimming and running speeds in D. quadramaculatus (a larger, more aquatic species) and in D. ocoee (a smaller, primarily terrestrial species). Prior to tail loss, aquatic burst speeds were greater than terrestrial burst speeds for individuals of D. quadramaculatus, but the converse was true for individuals of D. ocoee. During aquatic locomotion in each species, burst speed was significantly reduced after autotomy. With the loss of about 65% of tail length, swimming burst speed declined about 50% for D. quadramaculatus and 40% for D. ocoee. Terrestrial burst speed was not reduced in either species after autotomy. These results show that tail loss is costly for primarily aquatic desmognathine salamanders in terms of a reduction in maximal locomotor performance. The time required for caudal autotomy increased significantly with body size in each species, and larger individuals of D. quadramaculatus would bite prior to autotomy. Thus, larger individuals of D. quadramaculatus may utilize caudal autotomy less readily and rely more on alternative antipredator mechanisms such as biting, and this may be related to a higher locomotor cost of autotomy for such individuals.

Terrestrial versus aquatic phenotypes correlate with hydrological predictability of habitats in a semiterrestrial salamander (Urodela, Plethodontidae)

Terrestrial adaptations by small, desmognathine salamanders in Appalachian stream communities have been viewed as evolved responses to large, aquatic, predatory congeners. We tested the role of moisture in the development of adaptive phenotypes in the small, semiterrestrial Desmognathus ocoee . We measured indicators of relative ter- restrial vs. aquatic phenotypes (i.e. tolerance of desiccation, anatomical depression of body/tail) using individuals from stream habitats having different flow regimes within each of three geographical locations. Salamanders from intermittent, first-order streams exhibited greater desiccation tolerance, took longer to reach tolerance limits, and had more anatomically depressed bodies/tails than those from second-order, perennial streams, regardless of loca- tion. Phenotypes of salamanders from second-order streams showed aquatic tendencies. Phenotypic variation was consistent with relative habitat stability and not with relative abundance of large congeners. MtDNA analysis revealed that individuals grouped together based on geographical location and not habitat type, implying that the observed phenotypic differences arose in situ at each geographical location. Recent phylogenetic reconstructions of the Desmognathus indicate that large, aquatic forms are derived, and their appearance corresponds with the late Cenozoic development of modern Appalachian topography. We propose that radiation of desmognathine lifestyles and associated phenotypes tracked the formation of moisture-stability gradients associated with the creation of cool, wet, montane habitats. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 227- 238. ADDITIONAL KEYWORDS: adaptation - community - Desmognathus - moisture - terrestrial - variation.

Declines in Ravine-inhabiting Dusky Salamanders of the Southeastern US Coastal Plain

Gully-eroded and steephead valleys on Eglin Air Force Base in the Florida panhandle were sampled for the abundance of four species of ravine-inhabiting, plethodontid salamanders in two separate periods, 25 years apart. In this interval, Desmognathus auriculatus (Southern Dusky Salamander) appears to have gone extinct and the abundance of D. cf. conanti (Spotted Dusky Salamanders) has decreased by about 68%. There was no change in the average abundance of Eurycea cirrigera (Two- lined Salamander). Pseudotriton ruber (Red Salamanders) declined in ravines from which larger populations of D. auriculatus disappeared, but increased in ravines from which smaller populations of D. auriculatus had disappeared. There was a slight increase in the average abundance of P. ruber in ravines that were inhabited by D. cf. conanti, but those changes in P. ruber abundance were unrelated to the changes in the abundance of D. cf. conanti. Declines in populations of D. auriculatus were also noted in Louisiana and Georgia; evidence suggests that all of these declines began in the mid- 1970s. There are several potential causes of the regional declines, but no single explanation appears sufficient to explain declines in all populations. Feral pig rooting eliminates the larval seepage habitat of desmognathine salamanders and may be partly responsible for the declines on Eglin Air Force Base.

Antipredator Behaviors of the Red Hills Salamander, Phaeognathus hubrichti

The antipredator behaviors of Phaeognathus hubrichti (Red Hills Salamander), a large fossorial plethodontid, and the basal member of the desmognathine salamanders, are unknown. The responses of P. hubrichti to tongue-flicks from hand-held snakes, tapping with a rod and pinching with a forceps were recorded with a videocamera. When contacted by a snake tongue- flick, P. hubrichti exhibited several antipredator behaviors including immobility, gape, walk, run, head flatten, head elevation, flip, bite, and flinch. One other antipredator behavior—writhe—was observed in the field. The antipredator be- haviors of P. hubrichti are more similar to those species in its sister taxon, Desmognathus, than to those of other less closely related fossorial salamanders. Gape, a threat display, is nearly identical to that of Desmognathus quadramaculatus. Gape, bite, and writhe are proposed to be ancestral behaviors in this group.

Stifled sex in sympatry: patterns of sexual incompatibility among desmognathine salamanders

Sexual incompatibility due to differences in mate-recognition systems can be an important factor in preventing hybridization and gene flow between animal populations in sympatry. We tested in the laboratory for sexual incompatibility between populations of two species of desmognathine salamanders that occur in sympatry in south-eastern Kentucky, North America, Desmognathus monticola and D. welteri (Caudata: Plethodontidae: Desmognathinae). Spermatophore deposition and insemination (two related measures of sexual success) were frequent in intraspecific encounters, but interspecific encounters never resulted in the deposition of spermatophores by males (Experiment 1). The sexual behaviour patterns of these two species are similar qualitatively, but all encounters staged between them failed to progress beyond the most preliminary of courtship interactions (Experiment 2), perhaps due to species differences in chemosensory communication. Our data on sexual incompatibility between D. monticola and D. welteri are similar to those available for other desmognathine taxa that occur in sympatry. Review of a broader data-set on patterns of sexual incompatibility both within and between species, and in allopatry and in sympatry, provides evidence for both divergence of mate-recognition systems in allopatry and enhancement of sexual incompatibility in sympatry for desmognathine salamanders. We hypothesize that diversification in allopatry may be a consequence of natural and/or sexual selection acting to promote sexual success within populations. Enhancement in sympatry may be a consequence of subsequent selection for accurate species recognition under the threat of hybridization or gene flow between species.

Sexual behaviour of the Black Mountain dusky salamander (Desmognathus welteri), and the evolutionary history of courtship in the Desmognathinae

Plethodontid salamanders of the North American subfamily Desmognathinae offer excellent opportunities for an integrative understanding of the form, functions and phylogeny of sexual behaviour patterns. The first description of courtship in the Black Mountain dusky salamander Desmognathus welteri is presented. Once oriented toward their partners, males produce multiple tactile, visual and chemical stimuli that probably function to stimulate, or ‘persuade’, females to mate. Persuasion is accomplished by behaviour patterns that include head rubbing, butterfly, pulling and snapping, and perhaps nudging and tail undulation. Sperm transfer is indirect by a spermatophore that is deposited on the substrate during a sequence of behaviour patterns involving both sexes known as tail‐straddling walk. Fine‐scale synchronization and orientation of partners at this time is crucial for successful insemination. The evolutionary histories of eight sexual behaviour patterns for 19 taxa of desmognathine salamanders are then reconstructed. Our phyloethological analyses suggest that the courtship of desmognathines consists of a mosaic of ancestral (plesiomorphic) and derived (apomorphic) behavioural traits. The greatest variation among taxa involves behaviour patterns that are exhibited early in sexual encounters as, or shortly after, males orient toward females. Behaviour patterns that occur at closer range and most obviously are persuasive in function show less variation among taxa, and those that lead to sperm transfer (tail‐straddling walk) are invariant. While our phyloethological analyses reveal aspects of the evolutionary history of behavioural form in the Desmognathinae, further work is needed before thorough analyses of behavioural functions can be conducted.

Population and Species Divergence of Chemical Cues that Influence Male Recognition of Females in Desmognathine Salamanders

AbstractGrowing evidence indicates that males may be more discriminating of mating partners than often has been assumed. In the North American Ocoee dusky salamander, Desmognathus ocoee (Plethodontidae: Desmognathinae), sexual incompatibility among conspecific populations is high in encounters staged in the laboratory, at least in part because males fail to recognize ‘other’ females as appropriate targets for courtship. I used Y‐mazes to test the hypothesis that males of D. ocoee discriminate between substrate‐borne chemical cues produced by ‘own’ (homotypic) and ‘other’ (heterotypic) females. Males of four populations discriminated in favor of substrates soiled by homotypic females over clean (control) substrates (expt 1), suggesting that females produce chemical cues of sociosexual significance to males. Furthermore, males from these populations discriminated in favor of substrates soiled by homotypic females vs. substrates soiled by heterotypic females (expt 2), both conspecific and heterospecific (D. carolinensis and D. orestes). Thus, differences among populations and species in female chemical cues appear to affect the chemotactic responses of males. I suggest that, together with differences in behavioral signals and responses exhibited during courtship, differences in female chemical cues likely contribute to sexual incompatibility among populations and taxa of desmognathine salamanders.

All are one and one is all: sexual uniformity among widely separated populations of the North American seal salamander, Desmognathus monticola

The Modern Synthesis of the mid-20th century effectively buried typological definitions and descriptions of species and their boundaries. This interment is well supported by the large number of animal species for which substantial levels of sexual incompatibility have been found among conspecific populations, including some species of North American desmognathine salamanders that have restricted geographical ranges. We tested for sexual incompatibility and variation in sexual signals and responses among widely separated populations of the broadly distributed seal salamander, Desmognathus monticola . Levels of sexual incompatibility and differences in behaviour patterns exhibited during courtship and mating were modest to non-existent among these populations, despite the considerable geographical distances separating some of them. Our data are not consistent with results obtained in the majority of similar studies that have been conducted on congeneric species. For the seal salamander, we cannot reject the applicability of a typological species definition based on sexual compatibility and uniformity in the ethology of courtship among populations. We present five hypotheses (not necessarily mutually exclusive) that may explain our results. We suggest that recent range expansion, perhaps coupled with contemporary gene flow, may best explain sexual uniformity among populations of the seal salamander. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 1–10.

Life history of a small form of the plethodontid salamander Desmognathus quadramaculatus

AbstractWe sampled Desmognathus quadramaculatus, one of the largest species of plethodontid salamanders in eastern North America, from a population exhibiting extremely small adult body sizes in the Bald Mountains of North Carolina (USA). In order to test the hypothesis that miniaturization in desmognathine salamanders is due to early metamorphosis and maturation, we estimated ages and sizes at metamorphosis and maturation. Analysis of size-frequency distributions suggests that most larvae metamorphose after 24 months, with the remainder metamorphosing after 36. The minimum age of sexually mature individuals in the summer months is estimated to be 4 years in males and 5 years in females; some may mature 1 year earlier. This is earlier than other reliable estimates of age at maturation in D. quadramaculatus, and appears to account for the small size of the species at this locality. Larval and juvenile growth rates are within the range of growth rates of other populations. As in other populations of D. quadramaculatus, males are smaller than females at maturation, but grow to larger sizes. Estimates of clutch sizes based on dissection of gravid females are relatively low. The other species of salamanders in this community do not appear to be miniaturized.

SKELETOCHRONOLOGICAL ANALYSIS OF VARIATION IN AGE STRUCTURE, BODY SIZE, AND LIFE HISTORY IN THREE SPECIES OF DESMOGNATHINE SALAMANDERS

We evaluated age structure in three species of desmognathine salamanders at Coweeta Hydrologic Laboratory, North Carolina, for comparison with the results of an earlier study of age structure in these species at a nearby locality (Wolf Creek, North Carolina). At Coweeta, both Desmognathus quadramaculatus and D. monticola attain larger adult body sizes and greater ages than their Wolf Creek counterparts. The differences appear to stem in part from greater ages at sexual maturation in both species at Coweeta versus Wolf Creek. This disparity is most pronounced in D. quadramaculatus, where the estimated ages at first reproduction are 7–8 yr in males and 9–10 yr in females. The Coweeta populations of D. quadramaculatus and D. monticola may also have higher survivorship and higher rates of post-maturational growth than those at Wolf Creek. In contrast, in the third and smallest species, D. ocoee, the Coweeta population did not differ in size and age attributes from that at Wolf Creek. We hypothesize that the m...

The Leech, Oligobdella biannulata (Glossiphoniidae) on Desmognathine Salamanders: Potential for Trypanosome Transmission?

Abstract Four species of sympatric metamorphosed desmognathine salamanders collected from southern Appalachian mountain streams in western North Carolina were examined for the presence of the glossiphoniid leech, Oligobdella biannulata. Leeches were most frequently observed on Desmognathus quadramaculatus (prevalence and mean intensity = 22.6% and 2.8 ± 2.1, respectively). The largest leech infrapopulations (≥5 leeches/host) were observed on the largest individuals of D. quadramaculatus with 45.6% of the leeches observed found on five hosts, all of which were >82 mm SVL. The larger body size and more aquatic habitat requirements of this species, relative to Desmognathus monticola and D. ochrophaeus, increases the potential for transmission of leeches. Leeches were not found on the most aquatic salamander, D. marmoratus, nor the most terrestrial congener, D. ochrophaeus. The former species inhabits strong currents in streams; a habitat possibly limiting leech attachment and prolonged feeding. Leeches showe...

Sperm aggregations in the spermatheca of female desmognathine salamanders (Amphibia: Urodela: Plethodontidae).

The alignment of sperm in a cloacal sperm storage gland, the spermatheca, was studied in female desmognathine salamanders by scanning and transmission electron microscopy. Females representing nine species and collected in spring, late summer, and fall in the southern Appalachian Mountains contained abundant sperm in their spermathecae. The spermatheca is a compound tubuloalveolar gland connected by a single common tube to the middorsal wall of the cloaca. Sperm enter the common tube in small groups aligned in parallel along their axes, and continue in a straight course until encountering divisions of the common tube (neck tubules) or luminal borders of distal bulbs, which can act as barriers. Sperm may form tangles, in which small clusters retain their mutual alignment, at the branches of the neck tubules from the common tube, or in the lumen of the distal bulbs, where subsequent waves of sperm collide with sperm already present. The nuclei of some sperm from the initial group to encounter the walls of the distal bulbs appear to become embedded in secretory material on the luminal border or in the apical cytoplasm of the spermathecal epithelial cells. We propose that these sperm become trapped in the spermatheca and are ultimately degraded. J. Morphol. 238:143-155, 1998. © 1998 Wiley-Liss, Inc.

Courtship behaviour of the Ouachita dusky salamander, Desmognathus brimleyorum, and a comparison with other desmognathine salamanders

This paper provides the first description of the courtship of the North American Ouachita dusky salamander, Desmognathus brimleyorum (Plethodontidae: Desmognathinae). Heterosexual encounters consist of multiple sequences of courtship, each sequence ending with the deposition of a single spermatophore on the substratum. Insemination is most likely to occur at the end of the final sequence in an encounter. Each sequence contains behaviour patterns that function to orient and synchronize the partners, and enable the male to provide tactile (rubbing and nudging), chemical (snapping and pulling) and, perhaps, visual (jerking) stimulation to the female. In terms of the sequential structure of encounters, the courtship of D. brimleyorum is unique among desmognathine salamanders for which descriptions are available. However, each of the individual behaviour patterns exhibited by D. brimleyorum during sequences of courtship is shown by congeneric taxa. Understanding patterns of similarities among these taxa awaits a phylogenetic analysis of behavioural evolution in the monophyletic Desmognathinae.

Courtship in Desmognathine Salamanders: The Southern Dusky Salamander, Desmognathus auriculatus

-The courtship of the southern dusky salamander, Desmognathus auriculatus (Plethodontidae), is described for the first time. Most of a male's effort is expended in orienting to and stimulating (or 'persuading') his partner. Much of the stimulation provided by the male is tactile (nudging and rubbing), although he also exhibits behavior patterns associated with the transfer of courtship pheromones (snapping and pulling). Movements of the male's forelimbs may stimulate the female visually. The consummatory act of courtship is indirect sperm transfer by means of a spermatophore, and this stage of courtship appears identical in all desmognathines yet described. Courtship behavior patterns in the subfamily Desmognathinae are an apparent mosaic of ancestral and derived characters, with some evidence for homoplasy. Formal analyses of behavioral evolution await a robust phylogenetic hypothesis and detailed ethograms for multiple populations of all recognized taxa. The absence of lungs is a character shared by all salamanders in the family Plethodontidae (Duellman and Trueb, 1986). Reliance on cutaneous gas exchange may be a major constraint on the geographic distribution of these animals. The majority of taxa are found in relatively cool and moist habitats, especially in the montane regions of the Pacific Northwest and Appalachian Mountains of North America, and the cloud forests of Central America. An exceptional, but not unique, taxon is the southern dusky salamander, Desmognathus auriculatus (subfamily Desmognathinae), populations of which occur throughout the Gulf and Atlantic Coastal Plains of the southeastern United States. Winters typically are mild and summers warm and humid in these physiographic provinces. Well away from the mountains, D. auriculatus can be found in the organic debris along the shady margins of small streams, hypoxic pools and swamps. Little has been published on the natural history of the southern dusky salamander (but see Robertson and Tyson, 1950, for some observations of this species in eastern North Carolina). Here I report the first laboratory observations of this species' courtship and mating behavior. I then compare these to descriptions for other desmognathine salamanders, in anticipation of a formal, phylogenetic analysis of the evolution of courtship in this subfamily. MATERIALS AND METHODS Sexually mature D. auriculatus were collected in the summer of 1994 from several sites near the Savannah River Site in Aiken and Barnwell Counties, South Carolina (see Gibbons and Semlitsch, 1991). Most were found by raking through the organic debris on the margins of small pools. Desmognathus auriculatus is the only desmognathine that has been recorded in this part of South Carolina, although the presence of D. fuscus is possible (see Gibbons and Semlitsch, 1991). Each of my specimens was identified as D. auriculatus on the basis of body size, the presence of pale lateral spots, and the speckled appearance of the belly. Animals were transported to the laboratory in cooled containers, where they were maintained at approximately 15 C on a natural (Pullman, Washington) photoperiod. Salamanders were housed individually in plastic boxes measuring 9 x 17 x 31 cm, with a damp paper towel as substratum and a crumpled damp paper towel as a refuge. An ad libitum diet of vitamin-mineral dusted waxworms (moth larvae) was provided. I staged a total of seven heterosexual encounters between pairs of single males and females drawn from a pool of four males and two females. No two individuals were paired together more than once. Encounters were staged in a plexiglass observation arena measuring 17 x 17 x 5 cm, floored with a damp paper towel; no refuge was made available. Animals were introduced at approximately 1500 h and left together until 0800 h the following morning. All behavioral interactions were recorded under dim red illumination on a time-lapse videotape recorder (Panasonic AG-6010) using a low-light video camera (Panasonic WV-BD400).

Life-History Perspective of Adaptive Radiation in Desmognathine Salamanders

This study investigates interspecific variation in age at first reproduction, fecundity, and body size in multispecies assemblages of desmognathine salamanders. The hypotheses tested are that interspecific differences in body size among desmognathines stem proximately from variation in age at first reproduction and that variation in the latter trait is positively correlated with variation in fecundity among species. It is shown that a correlation between age at first reproduction and fecundity, combined with a uniform rate of survival, based on available estimates of these parameters, will yield equivalent values of net reproductive rate (Ro) among the species of a given assemblage. Such equivalence represents a form of life-history symmetry. Data from two assemblages are presented in support of the argument for symmetry. Such life-history symmetry may reflect uniformity in morphological specialization in desmognathines. Given the morphological adaptations to burrowing (head-wedging) in the subfamily, the relationship between adult body size and habitat preference in Desmognathus may reflect adaptation to the size of cover objects and composition of the substratum along the aquatic-terrestrial habitat gradient. I propose that these variables, in association with predation and competition, represent the selective factors responsible for body size diversification in Desmognathus.

2nd World Congress of Herpetology

Abstract Temporary removal sampling was used to investigate the population dynamics of the salamander Desmognathus monticola in the southern Appalachian Mountains, USA. Sampling was conducted over 5 years, mainly in July, on one or two plots each year, with seven removal samples being taken in each set of samples. By using size‐frequency distributions, it was possible to separately estimate population numbers for three juvenile age‐classes and a mixed age‐class of older individuals that included adults. Repetition of the procedure in successive years provided data for both time‐specific (vertical) and cohort life tables. Fecundity values obtained by dissection and age data derived by skeletochronology provided a means for refining the life table. The results confirmed and extended earlier findings of life‐history traits of D. monticola, and showed that annual survival rates of 0.5–0.6 are required for population equilibrium. Removal sampling is considered to be a promising technique for evaluating demographics in multispecies communities of desmognathine salamanders, but requires intensive sampling of relatively large plots over several years.