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Unstable Evolutionarily Stable Strategy and Oscillation: A Model of Lateral Asymmetry in Scale-Eating Cichlids

1994; University of Chicago Press; Volume: 144; Issue: 6 Linguagem: Inglês

10.1086/285722

1537-5323

Satoshi Takahashi, Michio Hori,

Primate Behavior and Ecology

A scale-eating cichlid, Perissodus microlepis, in Lake Tanganyika exhibits genetically determined right- or left-handedness of mouth opening. Since a minor type of two morphs has the advantage of attracting a prey's attention less, the evolutionarily stable strategy frequency of each morph is 0.5. However, data on the laterality of the scale eaters show oscillation around 0.5. This article develops a genetic model of frequency-dependent oscillation, which describes the conditions for the emergence of the oscillation as well as its period and amplitude. Strong frequency dependence of selection caused by the attention of prey is an essential factor for the oscillation. Although the model is simple, its prediction agrees well with the field data in both the period and the amplitude. Hence the model confirms the first finding of oscillation driven by frequency-dependent selection.