Levels of genetic variability in sculpins (Cottidae: Teleostei) of the North American Pacific coast and an assessment of potential correlates

We examined levels of allozymic variation in intertidal sculpins of the genera Oligocottus, Clinocottus and Artedius. Variability in these species, as assessed by the proportion of loci polymorphic and average heterozygosity per locus, was generally low but within the range of values observed for other fish groups. In reviewing the ecological and life‐history attributes of these sculpins, we found only one outstanding correlate of allozyme variability–larger‐bodied species tended to have lower levels of variation. Also, the level of heterozygosity was not related in any obvious way to historical/ evolutionary aspects such as position in phylogenetic trees or the inferred relative ages of species. Our study of a relatively well‐defined lineage of fishes that co‐occur in the same geographical region and in the same, or broadly similar, habitats, underscores the difficulty of detecting correlations between genetic variability and seemingly relevant ecological features of species.