Maan Martine E, Haesler Marcel P, Seehausen Ole, Van Alphen Jacques J M
Department of Animal Ecology, Institute of Biology, University of Leiden, 2300 RA Leiden, The Netherlands.
J Exp Zool B Mol Dev Evol. 2006 Mar 15;306(2):168-76. doi: 10.1002/jez.b.21083.
In many haplochromine cichlid fish, male nuptial coloration is subject to female mate choice and plays a central role in the evolution of reproductive isolation between incipient species. Intraspecific variation in male coloration may serve as a target for diversifying sexual selection and provide a starting point for species divergence. Here, we investigated a polychromatism in Neochromis omnicaeruleus, a haplochromine from Lake Victoria, East-Africa. In this species, male coloration ranges from skyblue to yellow-red and females are grey-blue to yellow. We found that both genetic and environmental factors influence the expression of these colours during individual development. In a natural population, we found that male colour was associated with size and sexual maturity: yellow males were smaller than blue males and tended to be sexually immature. In females, size and maturity did not differ between colour types. Laboratory crosses revealed that there is a heritable component to the observed colour variation: yellow parents produced more yellow offspring than blue parents. Together with repeated aquarium observations of yellow individuals that gradually become blue, these data suggest that yellow males change to blue as they approach sexual maturity, and that the occurrence and timing of this transition is influenced by both environmental and genetic effects. The significance of this mechanism of colour expression as a possible target for divergent selection remains to be evaluated.
在许多丽鱼科朴丽鱼属鱼类中，雄性的婚姻色受到雌性配偶选择的影响，并在初始物种间生殖隔离的进化中发挥核心作用。雄性体色的种内变异可能成为多样化性选择的目标，并为物种分化提供起点。在此，我们研究了东非维多利亚湖的朴丽鱼属鱼类全蓝新亮丽鲷的多态现象。在这个物种中，雄性体色从天蓝色到黄红色不等，而雌性则为灰蓝色到黄色。我们发现，遗传和环境因素在个体发育过程中都会影响这些颜色的表达。在一个自然种群中，我们发现雄性体色与体型和性成熟度有关：黄色雄性比蓝色雄性体型小，且往往未达到性成熟。在雌性中，不同体色类型的体型和成熟度并无差异。实验室杂交实验表明，观察到的颜色变异存在可遗传成分：黄色亲本产生的黄色后代比蓝色亲本更多。再加上在水族箱中反复观察到黄色个体逐渐变为蓝色，这些数据表明，黄色雄性在接近性成熟时会转变为蓝色，而且这种转变的发生和时间受到环境和遗传效应的共同影响。这种颜色表达机制作为分化选择可能目标的意义仍有待评估。
