Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
J Exp Zool B Mol Dev Evol. 2011 Jun 15;316(4):254-62. doi: 10.1002/jez.b.21395. Epub 2011 Jan 11.
Traits can evolve both in response to direct selection and in response to indirect selection on other linked traits. Although the evolutionary significance of coupled traits (e.g., through shared components of developmental pathways, or through competition for shared developmental resources) is now well accepted, we know comparatively little about how developmental coupling may restrict the independent responses of two or more phenotypically plastic traits in response to conflicting environmental cues. Such studies are important because coupled development, if present, could act as an important limit to the evolution of functionally independent plasticity in multiple traits. I tested whether developmental coupling can restrict the direction of plastic responses by studying how penis form and leg form--both highly plastic traits of barnacles--varied in response to differences in conspecific density and water velocity. Penis length and leg length in Balanus glandula varied in parallel with variation in wave-exposure but varied in opposite directions with variation in conspecific density. This study represents one of the rare tests of developmental coupling between multiple (demonstrably adaptive) plastic traits: Barnacle legs and penises appear to exhibit modular development that can respond concurrently--yet in independent directions--to conflicting environmental cues.
特征既可以响应直接选择，也可以响应对其他相关特征的间接选择而进化。虽然偶联特征（例如，通过发育途径的共享成分，或通过对共享发育资源的竞争）的进化意义现在已经被广泛接受，但我们对于发育偶联如何限制两个或更多表型可塑性特征对相互冲突的环境线索的独立反应知之甚少。这些研究很重要，因为如果存在发育偶联，它可能会成为多个特征中功能独立可塑性进化的重要限制。我通过研究藤壶的阴茎形态和腿形态（这两种都是高度可塑性的特征）如何响应同种密度和水流速度的差异来检验发育偶联是否可以限制可塑性反应的方向。在巴氏腺藤壶中，阴茎长度和腿长度与波浪暴露的变化呈平行变化，但与同种密度的变化呈相反方向变化。这项研究代表了对多个（明显适应性）可塑性特征之间发育偶联的罕见测试之一：藤壶的腿和阴茎似乎表现出模块化发育，可以同时响应——但方向独立——相互冲突的环境线索。
