title: Widespread positive but weak assortative mating by diet within stickleback populations.
abstract: Assortative mating - correlation between male and female traits - is common within populations and has the potential to promote genetic diversity and in some cases speciation. Despite its importance, few studies have sought to explain variation in the extent of assortativeness across populations. Here, we measure assortative mating based on an ecologically important trait, diet as inferred from stable isotopes, in 16 unmanipulated lake populations of three-spine stickleback. As predicted, we find a tendency toward positive assortment on the littoral-pelagic axis, although the magnitude is consistently weak. These populations vary relatively little in the strength of assortativeness, and what variation occurs is not explained by hypothesized drivers including habitat cosegregation, the potential for disruptive selection, costs to choosiness, and the strength of the relationship between diet and body size. Our results support recent findings that most assortative mating is positive, while suggesting that new approaches may be required to identify the environmental variables that drive the evolution of nonrandom mating within populations.
authors.affiliation: Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712.
authors.forename: Travis
authors.initials: T
authors.lastname: Ingram
authors.affiliation: Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712.
authors.forename: Yuexin
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712.
authors.forename: Racine
authors.initials: R
authors.lastname: Rangel
authors.affiliation: Department of Integrative Biology, University of Texas at Austin One University Station C0990, Austin, Texas, 78712 ; Howard Hughes Medical Institute, University of Texas at Austin One University Station C0990, Austin, Texas, 78712.
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Bolnick
keywords: Gasterosteus aculeatus; habitat cosegregation; magic trait; nonrandom mating; sympatric speciation