While it is universally recognised that environmental factors can cause phenotypic trait variation via phenotypic plasticity, the extent to which causal processes operate in the reverse direction has received less consideration. In fact individuals are often active agents in determining the environments, and hence the selective regimes, they experience. There are several important mechanisms by which this can occur, including habitat selection and niche construction, that are expected to result in phenotype–environment correlations (i.e. non-random assortment of phenotypes across heterogeneous environments). Here we highlight an additional mechanism – intraspecific competition for preferred environments – that may be widespread, and has implications for phenotypic evolution that are currently underappreciated. Under this mechanism, variation among individuals in traits determining their competitive ability leads to phenotype–environment correlation; more competitive phenotypes are able to acquire better patches. Based on a concise review of the empirical evidence we argue that competition-induced phenotype–environment correlations are likely to be common in natural populations before highlighting the major implications of this for studies of natural selection and microevolution. We focus particularly on two central issues. First, competition-induced phenotype–environment correlation leads to the expectation that positive feedback loops will amplify phenotypic and fitness variation among competing individuals. As a result of being able to acquire a better environment, winners gain more resources and even better phenotypes – at the expense of losers. The distinction between individual quality and environmental quality that is commonly made by researchers in evolutionary ecology thus becomes untenable. Second, if differences among individuals in competitive ability are underpinned by heritable traits, competition results in both genotype–environment correlations and an expectation of indirect genetic effects (IGEs) on resource-dependent life-history traits. Theory tells us that these IGEs will act as (partial) constraints, reducing the amount of genetic variance available to facilitate evolutionary adaptation. Failure to recognise this will lead to systematic overestimation of the adaptive potential of populations. To understand the importance of these issues for ecological and evolutionary processes in natural populations we therefore need to identify and quantify competition-induced phenotype–environment correlations in our study systems. We conclude that both fundamental and applied research will benefit from an improved understanding of when and how social competition causes non-random distribution of phenotypes, and genotypes, across heterogeneous environments.

中文翻译：

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社会竞争作为表型-环境相关性的驱动因素：对生态学和进化的影响

虽然普遍认为环境因素可以通过以下方式导致表型性状变异表型可塑性，因果过程以相反方向运作的程度受到的考虑较少。事实上，个人通常是决定环境的积极主体，因此他们所经历的选择性制度。有几种重要的机制可以发生这种情况，包括栖息地选择和生态位构建，预计这些机制会导致表型-环境相关性（即跨异质环境的非随机表型分类）。在这里，我们强调了一种额外的机制——对首选环境的种内竞争——它可能很普遍，并且对目前未被充分认识的表型进化有影响。在这种机制下，个体之间决定其竞争能力的性状差异导致表型-环境相关性；更具竞争力的表型能够获得更好的补丁。基于对经验证据的简要回顾，我们认为竞争诱导的表型 - 环境相关性可能在自然种群中很常见，然后强调这对自然选择和微进化研究的主要影响。我们特别关注两个核心问题。首先，竞争诱导的表型 - 环境相关性导致期望正反馈循环将放大竞争个体之间的表型和适应度变化。由于能够获得更好的环境，赢家获得了更多的资源，甚至更好的表型——以牺牲输家为代价。因此，进化生态学研究人员通常对个体质量和环境质量进行区分变得站不住脚。其次，如果个体之间竞争能力的差异是由遗传特征支撑的，那么竞争会导致基因型-环境相关性以及对资源依赖的生活史特征的间接遗传效应（IGE）的预期。理论告诉我们，这些 IGE 将充当（部分）约束，减少可用于促进进化适应的遗传变异量。未能认识到这一点将导致系​​统地高估人口的适应潜力。为了了解这些问题对自然种群生态和进化过程的重要性，我们需要在我们的研究系统中识别和量化竞争诱导的表型-环境相关性。我们得出结论，基础研究和应用研究都将受益于对社会竞争何时以及如何导致表型和基因型在异质环境中的非随机分布的更好理解。