Variability in connectivity indicated by chaotic genetic patchiness within and among populations of a marine fish

Abstract

Despite substantial advances in our understanding of marine population dynamics, there is still much uncertainty as to what processes influence connectivity, gene flow and population structure. To explore this, we examined the spatial and temporal variation in population genetic structure of adult and recently settled bicolor damselfish Stegastes partitus, a coral reef fish. We genotyped adult and juvenile fish from 10 sites over 4 sample years at 9 microsatellite loci. We show spatial heterogeneity in adult and juvenile population structure; however, we found no evidence of a pattern of spatial genetic divergence. Furthermore, genetic structure changed through time and between life stages in an unpredictable manner. Using these data, we test whether pre- or post- settlement selection, sweepstakes effects or variability in connectivity can explain the observed chaotic genetic patchiness. Our results indicate that the contributions of various larval sources likely change through time as a result of stochastic processes such as oceanographic flow. Our results have implications for the management of marine populations, as spatial and temporal variability in connec- tivity may act to promote long term stability of populations. Therefore it is important that marine management efforts account for such heterogeneity in the design of protected areas.