Density-dependent selection, which promotes contrasting patterns of trait means at different population densities, has a long history in population genetics and ecology. The unifying principle from theory is that density-dependent selection operates on phenotypic traits whose values counter the effects of whatever ecological agent is limiting population growth, be it resource competition, predators, or pathogens. However, the complexity inherent in density dependence means that the same selective process can generate multiple outcomes, depending upon the details of how population density affects vital rates and the age or size structure of a population. Failure to appreciate the potential for multiple outcomes confounded many early studies of the process. Nonetheless, careful empirical work in laboratory studies, long-term field studies, and studies of sexual selection demonstrates the wide reach of density-dependent selection. The inconsistent outcomes observed in these studies call for renewed research into how the details of density dependence channel adaptive responses.

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密度相关选择

密度依赖选择在群体遗传学和生态学中有着悠久的历史，它促进了不同种群密度下性状平均值的对比模式。理论的统一原则是，密度依赖选择对表型性状起作用，这些表型性状的值抵消了限制种群增长的任何生态因素的影响，无论是资源竞争、捕食者还是病原体。然而，密度依赖性固有的复杂性意味着相同的选择过程可以产生多种结果，具体取决于人口密度如何影响生命率以及人口的年龄或规模结构的细节。未能认识到多种结果的可能性使许多对该过程的早期研究感到困惑。尽管如此，实验室研究、长期实地研究和性选择研究中的仔细实证研究表明，密度依赖选择具有广泛的影响力。这些研究中观察到的不一致结果要求重新研究密度依赖的细节如何引导适应性反应。