Bossu Christen M, Near Thomas J
Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, 06520.
Evolution. 2015 May;69(5):1219-31. doi: 10.1111/evo.12655. Epub 2015 May 5.
It is not known how environmental pressures and sexual selection interact to influence the evolution of extravagant male traits. Sexual and natural selection are often viewed as antagonistic forces shaping the evolution of visual signals, where conspicuousness is favored by sexual selection and crypsis is favored by natural selection. Although typically investigated independently, the interaction between natural and sexual selection remains poorly understood. Here, we investigate whether sexual dichromatism evolves stochastically, independent from, or in concert with habitat use in darters, a species-rich lineage of North American freshwater fish. We find the evolution of sexual dichromatism is coupled to habitat use in darter species. Comparative analyses reveal that mid-water darter lineages exhibit a narrow distribution of dichromatism trait space surrounding a low optimum, suggesting a constraint imposed on the evolution of dichromatism, potentially through predator-mediated selection. Alternatively, the transition to benthic habitats coincides with greater variability in the levels of dichromatism that surround a higher optimum, likely due to relaxation of the predator-mediated selection and heterogeneous microhabitat dependent selection regimes. These results suggest a complex interaction of sexual selection with potentially two mechanisms of natural selection, predation and sensory drive, that influence the evolution of diverse male nuptial coloration in darters.
目前尚不清楚环境压力和性选择如何相互作用以影响雄性夸张性状的进化。性选择和自然选择通常被视为塑造视觉信号进化的拮抗力量，其中显眼性受性选择青睐，而拟态受自然选择青睐。尽管通常是独立研究的，但自然选择和性选择之间的相互作用仍知之甚少。在这里，我们研究了性二态性是否随机进化，是独立于北美淡水鱼物种丰富的镖鲈谱系中的栖息地利用，还是与之协同进化。我们发现镖鲈物种的性二态性进化与栖息地利用相关。比较分析表明，中水镖鲈谱系在低最优值周围表现出狭窄的二态性性状空间分布，这表明可能通过捕食者介导的选择对二态性进化施加了限制。或者，向底栖栖息地的转变与围绕较高最优值的二态性水平的更大变异性相吻合，这可能是由于捕食者介导的选择的放松和依赖微生境的异质选择机制。这些结果表明性选择与可能的两种自然选择机制（捕食和感官驱动）之间存在复杂的相互作用，这两种机制影响了镖鲈中不同雄性婚羽颜色的进化。
