Population Genomics of P. miniata along the Pacific Coastline Reveal Subtly Diverging Genomics Along an Extensive Range Gap

Many marine species exhibit range gaps, patchy distributions, or genetic disjunctions throughout their ranges. These discontinuities can result from various interacting mechanisms, though directly linking ecological and historical factors to observed distributions or genetic disjunctions often proves challenging. Intriguingly, substantial research has demonstrated that these spatial and genetic discontinuities frequently occur in species with long-lived planktonic larvae, which possess the capacity for extensive oceanic dispersal. This study investigates the population genetics of one such species, the bat star Patiria miniata. Despite its long-lived planktonic larval stage of six to ten weeks, P. miniata maintains both a range gap and a, geographically separate, strong genetic disjunction throughout its distribution from Alaska to Baja California. Utilizing low-coverage whole-genome sequencing of over 200 individuals collected throughout the P. miniata range between the early 2000s and 2023, we corroborate previous findings of a significant genetic disjunction across Queen Charlotte Sound, north of Vancouver Island. Additionally, we present new evidence of strong divergence at several genomic loci across an extensive range gap in Washington and Oregon, despite subtle genetic population structure at most loci here. Such differences may reflect more recent ecological or oceanographic barriers, rather than historical processes. Our results demonstrate that while marine invertebrate populations may appear panmictic based on genome-wide metrics of population structure alone, strong local selection for specific gene segments may be maintained in some populations. This research contributes to our understanding of the complex interplay between dispersal potential and local adaptation in marine ecosystems and highlights the importance of considering both genetic structure and finer-scale adaptation in coastal marine populations.