Dr. Paige Duffin
Post-Doc, USC MEB
Research Profile

The Fault in Our Stars: Distinct Genomic Patterns Separate Salish Sea and Pacific Outer Coast Populations of the Keystone Sea Star Pisaster ochraceus

Tuesday, March 4
11:30 AM
AHF 153 (Torrey Webb Room)

Abstract: Understanding the dispersal and population structure of marine species is critical in forecasting ecological responses to climate change. The ochre sea star (Pisaster ochraceus), a keystone predator in intertidal ecosystems along the North American Pacific coast, has long been considered a panmictic species due to its extended larval dispersal period and high potential for gene flow. This study aimed to characterize the genomic architecture of P. ochraceus using whole-genome sequencing (WGS) data from individuals spanning nearly 2,900 km of coastline from Alaska to Baja California. Our analyses of putatively neutral SNPs reveal pronounced population structure between outer Pacific coast populations and those residing within the semi-enclosed estuary of the Salish Sea, suggesting restricted gene flow and demographic divergence between these regions. The genomic divergence is further supported by evidence of selection, with putatively adaptive loci highlighting extended regions of low diversity in the Salish Sea population, consistent with recent selective sweeps and potential local adaptation to the distinct estuarine conditions. These findings suggest that oceanographic barriers and environmental heterogeneity play a significant role in shaping population structure in P. ochraceus, challenging the prevailing notion of panmixia. By exploring neutral and adaptive genetic diversity in this threatened marine organism, we provide valuable insights for its conservation and management in a rapidly changing world.