Widespread positive but weak assortative mating by diet within stickleback populations

摘要: Assortative mating – correlation between male and female traits is common within populations has the potential to promote genetic diversity in some cases speciation. Despite its importance, few studies have sought explain variation extent of assortativeness across populations. Here, we measure assortative based on an ecologically important trait, diet as inferred from stable isotopes, 16 unmanipulated lake three-spine stickleback. As predicted, find a tendency toward positive assortment littoral–pelagic axis, although magnitude consistently weak. These vary relatively little strength assortativeness, what occurs not explained by hypothesized drivers including habitat cosegregation, for disruptive selection, costs choosiness, relationship body size. Our results support recent findings that most positive, while suggesting new approaches may be required identify environmental variables drive evolution nonrandom