Resource allocation and life history traits of plethodon cinereus at different elevations

Abstract

Ecologists have long studied extrinsic factors to explain intraspecific variation in phenotypic expression, yet assessment of intrinsic factors may also be important in understanding intraspecific phenotypic variation. Resources are allocated among the competing life history traits of growth, reproduction and storage. Thus, assessment of the suite of these traits may be critical to better understand phenotypic expression of life history traits. We examined growth (body size), reproduction (reproductive frequency) and storage (tail fat) of museum specimens of Red-backed Salamanders, Plethodon cinereus, at low and high elevations to test how altitudinal differences affected resource allocation among these life history traits. Based on the findings from previous studies, we hypothesized that animals at high elevations would be smaller in body size, reproduce less frequently and have less fat storage. We found that adult animals at high elevations were smaller in body size, reproduced less frequently (only females), but had greater tail fat storage relative to their body size than their counterparts at low elevations. The stored fat on tails can be used when salamanders are short of food. It may be more crucial for animals at high elevations to store more fuel for survival because longer and colder winters prevent them from actively foraging for longer periods. Our results suggest that resource allocation to growth and reproduction may be more constrained at high elevations because of the shorter growing season and greater allocation of energy into storage.