What doesn’t kill them makes them stronger: An association between elongation factor 1-α overdominance in the sea star Pisaster ochraceus and "sea star wasting disease”
In recent years, a massive plague has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease, known as 'sea star wasting disease' (SSWD), is thought to be caused by viral infection. In the affected sea star Pisaster ochraceus, previous work had identified that the elongation factor 1-α (EF1A) locus harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations of P. ochraceus to identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased infection or mortality rates in individuals that are heterozygous at this locus. These results suggest further studies to understand the functional relationship between diversity at EF1A and survival in P. ochraceus.