Meeting Abstract
The most recent epidemic of sea star wasting disease (SSWD) across the Pacific Northwest has been the most deadly and geographically widespread in the disease’s history. SSWD affects many different species of sea stars, prompting questions about how the disease responds to and shapes local genetics in populations that it affects. Previous work on one affected sea star, Pisaster ochraceus, has shown that the elongation factor 1-alpha intronic insertion allele (EF1-a), is lethal when homozygous but maintained in populations by heterozygote advantage. In Pisaster, individuals that were heterozygous at this locus showed a decreased occurrence of SSWD. In this study, we examine the relationship between EF1-a genetic variation and SSWD in three species of the affected sea star Leptasterias. Stars were collected before the onset of the SSWD epidemic as well as during the epidemic. The stars collected during the epidemic were scored for wasting symptoms in the field. Preliminary data suggest that EF1-a intron 4 in Leptasterias displays directional selection or heterozygote advantage during wasting conditions. Comparisons of pre-wasting stars from CA (n=19), and wasting (n=10) and non-wasting (n=14) stars from Pigeon Point, CA and the San Juan Islands, WA revealed a shift in allele and genotype frequency from pre-epidemic conditions to during-epidemic conditions. These results provide valuable information to address questions about the impact of severe epidemics on population genetic variation.
