Abstract

Body-size variation in desmognathan salamanders in the southern Appalachian Mountains is coupled with trade-offs among life-history traits that affect growth, survival, and reproduction. Reproductive effort is an important trait that is often measured as the gonadosomatic index (GSI), defined as clutch mass relative to total body mass. I measured GSI as brood mass relative to maternal body mass in two assemblages of Desmognathus in the Cowee and Nantahala mountains of southwestern North Carolina. I also re-evaluated the size–fecundity relationship in the Nantahala Mountain assemblage on the basis of newer data. In addition, I examined the potential trade-off between number and size of offspring in several species in both assemblages. Among species, GSI decreased slightly with increasing body size; the trend is considered a probable effect of decreasing metabolic rate with body size rather than a trade-off with one or another life-history trait. Although both propagule size and number increased with body size among species, the rate of increase in the latter was lower than expected, suggesting a trade-off related to the advantages of larger vs. smaller propagules in larger vs. smaller species. To further assess reproductive traits, I summarized published estimates of key developmental ages in these species. I discuss the results in the context of the correlation between body size and habitat associations in Desmognathus, i.e., the adaptation of larger species to more aquatic (stream) and smaller species to more terrestrial (forest) habitats.