Evidence of disassortative mating in a Tanganyikan cichlid fish and its role in the maintenance of intrapopulation dimorphism |
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Authors: | Takahashi Tetsumi Hori Michio |
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Affiliation: | Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan. tetsumi@terra.zool.kyoto-u.ac.jp |
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Abstract: | Morphological dimorphism in the mouth-opening direction ('lefty' versus 'righty') has been documented in several fish species. It has been suggested that this deflection is heritable in a Mendelian one-locus, two-allele fashion. Several population models have demonstrated that lateral dimorphism is maintained by negative frequency-dependent selection, resulting from interactions between predator and prey species. However, other mechanisms for the maintenance of lateral dimorphism have not yet been tested. Here, we found that the scale-eating cichlid fish Perissodus microlepis exhibited disassortative mating, in which reproductive pairings between lefties and righties occurred at higher than expected frequency (p<0.001). A previous study reported that a lefty-righty pairing produces a 1:1 ratio of lefty:righty young, suggesting that disassortative mating contributes to the maintenance of lateral dimorphism. A combination of disassortative mating and negative frequency-dependent selection may stabilize lateral dimorphism more than would a single mechanism. |
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Keywords: | phenotypic polymorphism scale-eating cichlid Perissodus microlepis Lake Tanganyika |
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