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Color polymorphism and sex ratio distortion in a cichlid fish as an incipient stage in sympatric speciation by sexual selection
Author(s) -
Seehausen,
Van Alphen,
Lande
Publication year - 1999
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.1999.00098.x
Subject(s) - sympatric speciation , biology , cichlid , sexual selection , sympatry , disruptive selection , genetic algorithm , ecological speciation , mating , gene flow , ecology , evolutionary biology , reproductive isolation , incipient speciation , assortative mating , zoology , sex ratio , selection (genetic algorithm) , natural selection , population , genetics , genetic variation , fish <actinopterygii> , fishery , gene , demography , sociology , artificial intelligence , computer science
We investigated a Lake Victoria cichlid with a complex colour polymorphism that apparently represents one original species and two incipient species, all of which are sympatric. In laboratory breeding experiments we observed sex ratio distortion in certain matings between original and incipient species. Mate choice experiments show that males of the incipient species exhibit mating preferences against the original species, and males and females of the original species exhibit strong mating preferences against the incipient species. Mating preferences might evolve by sex ratio selection to avoid matings with distorted progeny sex ratios. Phenotype frequencies in nature suggest that mating preferences translate into mating frequencies, thus restricting gene flow and exerting disruptive sexual selection between the original and incipient species. The incipient species do not differ in morphology or ecology from the original species, implying that colour polymorphism, associated with sex ratio distortion, can be an incipient stage in sympatric speciation, and that disruption of gene flow can precede ecological differentiation.