Abstract
Often population genetic studies focus on patterns at a regional scale and use spatially aggregated samples to draw inferences about population structure and drivers, potentially masking ecologically relevant population sub-structure and dynamics. In this study we use a multidisciplinary approach combining genomic, demographic, and habitat data with an oceanographic particles drift model, to unravel the patterns of genetic structure on different scales in the black goby (Gobius niger) along the Norwegian coast. Using a high-density sampling protocol, we observed restricted gene flow both at a surprisingly fine (kilometres) and large (100km) scale. Our results showed a pattern of isolation by distance related to the level of ocean exposure along the Skagerrak coast, where sheltered sampling stations had an overall level of genetic divergence about three times higher (FST =0.0046) than that among exposed samples (FST =0.0015). These results were also supported by demographic analyses which showed that synchrony decreases with increasing distance at much smaller scales for sheltered samples (20 km) that for exposed ones (80 km), suggesting higher levels of gene flow among the latter. We also found a pronounced genetic discontinuity between populations along the Norwegian west and east coasts with sharp increasing in genetic divergence around the southern tip of Norway, likely driven by both lack of habitat and oceanography.
Competing Interest Statement
The authors have declared no competing interest.
