![]() ![]() Indeed, if male colour tightly coevolved with female preference, we would expect to find cases of parallel speciation whereby unrelated populations that independently evolved similar male coloration would freely interbreed. A powerful way of testing the role of male colour-female preference coevolution in producing prezygotic isolation among these species is to test whether assortative mating of populations can be predicted based on similarity of independently derived colour patterns. Molecular phylogenetic analysis using microsatellites and genome-wide surveys of Amplified Fragment Length Polymorphisms (AFLPs) indicate that some of these populations have evolved similar colours independently. Similar adult male coloration can be found in populations from widely separated localities within Lake Malawi. ![]() Laboratory mate choice trials with closely related populations have indicated substantial, albeit incomplete, assortative mating between populations that differ substantially in male colour and random mating between populations with more similar colour, suggesting that colour differentiation may play a pivotal role in prezygotic isolation. Allopatric colour variants are common among the rock-dwelling haplochromine species of Lake Malawi, and a substantial proportion of the estimated species richness of these fish is based on the allocation of species status to allopatric colour variants. It has been proposed that differentiation of mating traits under divergent sexual selection among allopatric populations may contribute to the high diversity of these lineages. The breakdown of assortative mating between a pair of sympatric Lake Victoria cichlid species in turbid waters, the breakdown of assortative mating during laboratory experiments under monochromatic light, and the observation that non-hybrid females prefer hybrid males that have the colours of conspecifics provided evidence that female mating preferences for male courtship hue are important in reproductive isolation in Lake Victoria cichlids.Ĭichlid fishes specialised to live on rocky shores are known to be philopatric and poor dispersers, with significant genetic structure among populations isolated by habitat discontinuities. The observations that individual females can have preferences for different male colour patterns and that these preferences lead to reproductive isolation between incipient species have been used to model speciation in cichlid radiations ]. Because many closely related species differ in sexually dimorphic male breeding colour, many studies on cichlid fishes from Lakes Malawi and Victoria have emphasized the possible role of female choice of male nuptial colour as a driving force for speciation. Sexual selection is thought to have played an important role in major adaptive radiations, such as those of Hawaiian Drosophila and East African cichlid fishes. One of the most significant recent development in speciation theory has been the increased attention given to sexual selection as an evolutionary force capable of rapidly inducing reproductive isolation among populations. ![]()
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