Phenotypic differences in life history traits in refuge populations of Pahrump Poolfish

Authors: Shawn C. Goodchild, Craig A. Stockwell

Year: 2013 (xlv)

Abstract

The plight of native desert fishes have led managers to use aggressive conservation measures such as the establishment of refuge populations as a hedge against extinction. Such managed relocation has been debated for narrowly endemic aquatic species (Oldham et al 2011; Cons Biol 25(1):40-47). However, there is a risk that the translocated populations could evolutionarily diverge in directions inappropriate for recolonization. For example, Devils Hole pupfish, Cyprinodon diabolis, within three refuges changed genetically and phenotypically from their parental population (Wilcox and Martin 2006; Animal Conserv 9: 316-321). The complexities of aquatic species conservation are well illustrated by the Pahrump Poolfish, Empetrichthys latos latos, an endangered species with a complicated history involving numerous refuge populations established at various sites in Nevada. Because of their imperiled status, it is useful to evaluate if local populations have rapidly diverged, or display different phenotypes, in response to local selective pressures. Currently, six poolfish populations persist at three sites, which are very different from the original spring, including lower-temperature lacustrine and stream habitats. At three points during the reproductive season we measured life history and phenotypic characteristics of three populations of poolfish, the Shoshone Stock Pond and South Well outflow, White Pine County, and Lake Harriet, Spring Mountain Ranch State Park, Clark County, Nevada. Fat content, reproductive allocation, and egg size varied between populations and times, suggesting both interpopulation difference in characteristics and phenology of asynchronous ovary development. These changes could affect options for agencies to manage the populations, or predict how a group would change when stocked in different refuges.