Department of Biological and Environmental Science, Centre of Excellence in Evolutionary Research, University of Jyväskylä, , PO Box 35, 40014 Jyväskylä, Finland.
Proc Biol Sci. 2012 Jan 22;279(1727):257-65. doi: 10.1098/rspb.2011.0880. Epub 2011 Jun 8.
The coloration of species can have multiple functions, such as predator avoidance and sexual signalling, that directly affect fitness. As selection should favour traits that positively affect fitness, the genes underlying the trait should reach fixation, thereby preventing the evolution of polymorphisms. This is particularly true for aposematic species that rely on coloration as a warning signal to advertise their unprofitability to predators. Nonetheless, there are numerous examples of aposematic species showing remarkable colour polymorphisms. We examined whether colour polymorphism in the wood tiger moth is maintained by trade-offs between different functions of coloration. In Finland, males of this species have two distinct colour morphs: white and yellow. The efficacy of the warning signal of these morphs was tested by offering them to blue tits in the laboratory. Birds hesitated significantly longer to attack yellow than white males. In a field experiment, the survival of the yellow males was also higher than white males. However, mating experiments in the laboratory revealed that yellow males had lower mating success than white males. Our results offer an explanation for the maintenance of polymorphism via trade-off between survival selection and mating success.
物种的颜色可能具有多种功能，例如避免捕食者和性信号传递，这些功能直接影响适应度。由于选择应该有利于对适应度产生积极影响的特征，因此该特征的相关基因应该达到固定状态，从而防止多态性的进化。对于依赖颜色作为警告信号来向捕食者宣传其不可食用性的警戒物种来说，这一点尤其正确。尽管如此，仍有许多例子表明警戒物种表现出显著的颜色多态性。我们研究了在木虎蛾中，颜色多态性是否是通过颜色不同功能之间的权衡来维持的。在芬兰，这种物种的雄性有两种截然不同的颜色形态：白色和黄色。通过在实验室中向蓝山雀提供这些形态，测试了这些形态警告信号的有效性。鸟类对黄色雄性的攻击犹豫时间明显长于白色雄性。在野外实验中，黄色雄性的存活率也高于白色雄性。然而，实验室中的交配实验表明，黄色雄性的交配成功率低于白色雄性。我们的研究结果为通过生存选择和交配成功率之间的权衡来维持多态性提供了一个解释。
