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A STOCHASTIC SIMULATION STUDY ON SPECIATION BY SEXUAL SELECTION
Author(s) -
Wu ChungI
Publication year - 1985
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1985.tb04080.x
Subject(s) - biology , allopatric speciation , sympatric speciation , locus (genetics) , population , reproductive isolation , genetics , allele , evolutionary biology , sexual selection , mutation rate , mating , demography , gene , sociology
A two‐locus multi‐allele sexual isolation model incorporating mutation and genetic drift which was first proposed by Nei et al. (1983) is studied here. One locus controls the male mating character, and the other controls female receptivity. All females are assumed to have equal mating success. Therefore, the frequencies of female receptivity alleles are changed by mutation, drift, and hitchhiking with male character alleles. Without hitchhiking, development of sexual isolation between allopatric populations proceeds faster in smaller populations, as expected. The hitchhiking effect, by triggering the mutual reinforcement of mating behavior of both sexes (or the runaway process, Fisher [1958]), speeds up the evolution of sexual isolation significantly. For populations with 2 Nv ≤ 0.2 ( N = population size, ν = mutation rate), the rates of divergence all approach the maximum possible rate. Sympatric sexual isolation develops quite frequently if two favorable conditions are met: 1) There is no selection on female phenotype (except in some limited cases), and 2) The population size is large enough to carry several female receptivity alleles. Because of stochastic factors, these alleles may lead to the formation of two discrete groups of females, each group receptive to males of different mating characters. The formation of sympatric sexually‐isolated groups is also aided significantly, at the incipient stage, by the runaway process.