Abstract approved:

The 100 North Pacific rockfish species in the genus Sebastes are highly diverse. Rockfishes fertilize their eggs internally and release swimming larvae. Complex courting behaviors may allow female rockfish to be selective about their mates and may promote and maintain speciation. In this study, I applied genetic techniques to survey the factors that structure rockfish populations and have potential to affect speciation. First, I used microsatellites to test the hypothesis that the rangewide signal of isolation-by-distance previously identified in copper rockfish is the result of localized habitat or oceanographic breaks. I found significant population divergence at both the whole-coast and Oregon-coast scales. I also identified a weak but significant barrier to larval migration south of Newport, Oregon. Second, I used a candidate gene approach to assess the possibility that olfactory receptor related to class A, type 2 (Ora2) genes could differentiate species at mating. I characterized sequence variation in Ora2 genes between five distantly-related rockfishes and tested for evidence of positive selection. My results suggest that rockfishes possess a single, highly conserved Ora2 gene. Although evidence of positive selection was found fo