Details

Autor(en) / Beteiligte

• Nagel, Laura
• Schluter, Dolph

Titel

Body Size, Natural Selection, and Speciation in Sticklebacks

Ist Teil von

• Evolution, 1998-02, Vol.52 (1), p.209-218

Ort / Verlag

United States: Society for the Study of Evolution

Erscheinungsjahr

1998

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• There is little evidence from nature that divergent natural selection is crucial to speciation. However, divergent selection is implicated if traits conferring adaptation to alternative environments also form the basis of reproductive isolation. We tested the importance of body size differences to premating isolation between two sympatric sticklebacks. The species differ greatly in size, and several lines of evidence indicate that this difference is an adaptation to alternative foraging habitats. Strong assortative mating was evident in laboratory trials, but a few hybridization events occurred. Probability of interspecific mating was strongly correlated with body size: interspecific spawning occurred only between the largest individuals of the smaller species and the smallest individuals of the larger species. Probability of spawning between similar-sized individuals from different species was comparable to spawning rates within species. Disruption of mating between individuals from different species can be traced to increased levels of male aggression and decreased levels of male courtship as size differences increased between paired individuals. Interspecific mate preferences in sympatric sticklebacks appears to be dominated by body size, implicating natural selection in the origin of species.