Rock‐Face Populations of the Mountain Salamander, Desmognathus Ochrophaeus, In North Carolina

Abstract

The ecology and life history of Desmognathus ochrophaeus inhabiting wet rock faces at high elevations near Highlands, North Carolina, were studied. Comparisons were made with rock—face populations in Great Smoky Mountains National Park and with woodland populations at Rabun Bald, Scaly Mountain, and Blue Valley in the Blue Ridge Mountains. The reproductive cycle in rock—face populations is annual; spawning occurs mostly in July and August, and females begin to emerge from brooding as early as late August. The new spermatogenic cycle begins in May and June. Animals on rock faces average 40—45 cm in movements between successive captures and appear to have a limited range. Animals displaced to the base of the rock face and higher on the rock face can return to their home range. Population density is high (up to 25 individuals/m2), diurnal activity is nearly as high as nocturnal activity (correlated with subdued body colors), and at least a moderate level of activity occurs during warm winter periods. Animals mature at 2 years of age as in woodland populations, but at a smaller size, and grow more slowly thereafter. Small body size is not due to paucity of food on the rock faces. The high population densities on the wet rock faces indicate that they are highly favorable habitats for D. ochrophaeus. Differences between rock—face and forest—floor populations are attributable to modified selective pressures in the two different ecological settings. Variation among rock—face populations is attributed to the intensity of selection for small body size and cryptic coloration, the size of the rock face, and variation among forest—floor populations from which they were derived. Since rock—face populations are linked genetically to surrounding forest—floor populations of D. ochrophaeus, they cannot be considered examples of taxonomic variation, but rather of ecotypic variation.