Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
J Evol Biol. 2010 May;23(5):914-24. doi: 10.1111/j.1420-9101.2010.01960.x. Epub 2010 Mar 12.
The hypothesis of sympatric speciation by sexual selection has been contentious. Several recent theoretical models of sympatric speciation by disruptive sexual selection were tailored to apply to African cichlids. Most of this work concludes that the genetic architecture of female preference and male trait is a key determinant of the likelihood of disruptive sexual selection to result in speciation. We investigated the genetic architecture controlling male nuptial colouration in a sympatric sibling species pair of cichlid fish from Lake Victoria, which differ conspicuously in male colouration and female mating preferences for these. We estimated that the difference between the species in male nuptial red colouration is controlled by a minimum number of two to four genes with significant epistasis and dominance effects. Yellow colouration appears to be controlled by one gene with complete dominance. The two colours appear to be epistatically linked. Knowledge on how male colouration segregates in hybrid generations and on the number of genes controlling differences between species can help us assess whether assumptions made in simulation models of sympatric speciation by sexual selection are realistic. In the particular case of the two sister species that we studied a small number of genes causing major differences in male colouration may have facilitated the divergence in male colouration associated with speciation.
性选择的同域物种形成假说一直存在争议。最近有几个关于性选择导致异域物种形成的中断的理论模型是专门针对非洲慈鲷设计的。这些工作大多得出结论，认为雌性偏好和雄性特征的遗传结构是中断性选择导致物种形成的可能性的关键决定因素。我们调查了控制维多利亚湖慈鲷鱼类同域亲缘种对雄性婚色遗传结构的控制，这些种对雄性颜色和雌性对这些颜色的交配偏好有明显的差异。我们估计，物种间雄性婚红色差异由具有显著上位性和显性效应的 2 到 4 个基因控制。黄色颜色似乎由一个具有完全显性的基因控制。两种颜色似乎是上位连锁的。了解雄性颜色在杂种世代中的分离情况以及控制物种间差异的基因数量，可以帮助我们评估性选择导致同域物种形成的模拟模型中的假设是否现实。在我们研究的两个姐妹种的特殊情况下，导致雄性颜色差异的少数基因可能促进了与物种形成相关的雄性颜色的分歧。
