The Covariance between Genetic and Environmental Influences across Ecological Gradients Reassessing the Evolutionary Significance of Countergradient and Cogradient Variation
The Covariance between Genetic and Environmental Influences across Ecological Gradients Reassessing the Evolutionary Significance of Countergradient and Cogradient Variation
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DOI：
10.1111/j.1749-6632.2009.04575.x
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发表时间：
2009-01-01
期刊：
影响因子：
--
通讯作者：
Hice, Lyndie A.
中科院分区：
文献类型：
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作者：
Conover, David O.;Duffy, Tara A.;Hice, Lyndie A.
跨环境梯度（如纬度、海拔）的表型变化模式长期以来一直吸引着进化生态学家的兴趣。表型变化的模式和幅度是由遗传和环境影响在一个梯度上的协方差决定的。共梯度变异（CoGV）发生在协方差为正的情况下：即遗传和环境对表型表达的影响是一致的，它们的共同影响突出了整个梯度上平均性状值的变化。相反，当协方差为负时，反梯度变异（CnGV）就会发生：即遗传和环境对表型的影响是相互对立的，从而减少了整个梯度上平均性状表达的变化。到目前为止，已经在至少60个物种中发现了CnGV，大多数例子来自跨越纬度或海拔梯度的鱼类、两栖动物和昆虫。表现CnGV的性状通常涉及代谢补偿，即提高各种生理速率过程（发育、生长、摄食、代谢、活动），以抵消温度降低、生长季节长度或食物供应的抑制作用。已确定的CoGV的例子要少得多（11种），这些例子通常涉及形态特征。对空间协方差模式知识的增加进一步加深了我们对伯格曼大小曲线、表型可塑性、物种范围限制、权衡的理解；在幼鱼生长速率方面，以及野生物种保护策略的设计。此外，时间CnGV解释了一些明显缺乏对方向选择的表型响应的情况，并为预测对气候变化的进化响应提供了一个框架。
Patterns of phenotypic change across environmental gradients (e.g., latitude, altitude) have long captivated the interest of evolutionary ecologists. The pattern and magnitude of phenotypic change is determined by the covariance between genetic and environmental influences across a gradient. Cogradient variation (CoGV) occurs when covariance is positive: that is, genetic and environmental influences on phenotypic expression are aligned and their joint influence accentuates the change in mean trait value across the gradient. Conversely, countergradient variation (CnGV) occurs when covariance is negative: that is genetic and environmental influences on phenotypes oppose one another, thereby diminishing the change in mean trait expression across the gradient. CnGV has so far been found in at least 60 species, with most examples coming from fishes, amphibians, and insects across latitudinal or altitudinal gradients. Traits that display CnGV most often involve metabolic compensation, that is, the elevation of various physiological rates processes (development, growth, feeding, metabolism, activity) to counteract the dampening effect of reduced temperature, growing season length, or food supply. Far fewer examples of CoGV have been identified (11 species), and these most often involve morphological characters. Increased knowledge of spatial covariance patterns has furthered our understanding of Bergmann size clines, phenotypic plasticity, species range limits, tradeoffs; in juvenile growth rate, and the design of conservation strategies for wild species. Moreover, temporal CnGV explains some cases of an apparent lack of phenotypic response to directional selection and provides a framework for predicting evolutionary responses to climate change.