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EFFECTS OF MIGRATION ON THE GENETIC COVARIANCE MATRIX
Author(s) -
Guillaume Frédéric,
Whitlock Michael C.
Publication year - 2007
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.1558-5646.2007.00193.x
Subject(s) - biology , population , intraspecific competition , divergence (linguistics) , evolutionary biology , selection (genetic algorithm) , gene flow , introgression , genetics , genetic variation , ecology , gene , demography , linguistics , philosophy , artificial intelligence , sociology , computer science
In 1996, Schluter showed that the direction of morphological divergence of closely related species is biased toward the line of least genetic resistance, represented by g max , the leading eigenvector of the matrix of genetic variance–covariance (the G ‐matrix). G is used to predict the direction of evolutionary change in natural populations. However, this usage requires that G is sufficiently constant over time to have enough predictive significance. Here, we explore the alternative explanation that G can evolve due to gene flow to conform to the direction of divergence between incipient species. We use computer simulations in a mainland–island migration model with stabilizing selection on two quantitative traits. We show that a high level of gene flow from a mainland population is required to significantly affect the orientation of the G ‐matrix in an island population. The changes caused by the introgression of the mainland alleles into the island population affect all aspects of the shape of G (size, eccentricity, and orientation) and lead to the alignment of g max with the line of divergence between the two populations' phenotypic optima. Those changes decrease with increased correlation in mutational effects and with a correlated selection. Our results suggest that high migration rates, such as those often seen at the intraspecific level, will substantially affect the shape and orientation of G , whereas low migration (e.g., at the interspecific level) is unlikely to substantially affect the evolution of G .