Multi-trait Selection and the Evolution of the Integrated Phenotype.

[摘要] Trade-offs are fundamental to understanding the origin and maintenanceof biological diversity.In particular, phenotypic evolution ispredicted to depend critically on the shapes of the trade-offfunctions relating fitness costs and benefits to trait expression.Existing studies have focused on understanding the evolution of singletraits. This approach assumes that traits are independent, despite therecognition that phenotypic traits are often highly integrated.Thisintegration suggests that selection will often be multivariate, sothat trade-offs underlying individual traits will affect the evolutionof other phenotypic traits as well.Here I apply these insights to anumber of questions.In the first chapter, I ask how selection actingon energy allocation and behavior simultaneously can lead toqualitatively different expressions of predator-induced defenses.Ishow that different shapes of the trade-off between foraging gain andpredation risk lead to defense strategies that alter energy allocationonly, behavior only, or both simultaneously in response to predationrisk.The second chapter extends these insights to explore theevolutionary emergence of phenotypic polymorphism. I ask whetherselection acting on both body size and behavior leads to differentevolutionary outcomes from either single-trait case.I show that,depending on the shapes of the underlying phenotypic trade-offs,multivariate selection can lead to evolutionary branching whenunivariate selection predicts a global optimum and predicting a globaloptimum when univariate selection predicts evolutionary branching.The final chapter uses phylogenetic comparative analysis to study theadaptive evolution of amphibian morphology and behavior. Usingmeasurements of trait means and plasticities, a novel phylogeny, andextensive habitat data, I test whether species differences in habitatchoice have adaptive consequences for phenotypic evolution. I findstrong support for the hypothesis that body size and behavioralplasticity have adaptively evolved in response to changes in pondhydroperiod and predation risk. Other morphological traits appear tobe highly constrained or under strong stabilizing selection.Thesestudies show that understanding phenotypic evolution requiresconsidering how selection acts on the entire phenotype, rather thanatomized traits, and accounting for the interactions among thetrade-offs underlying trait expression.

[发布机构] University of Michigan

[效力级别] Phenotypic Plasticity

[关键词] Life History Theory;Phenotypic Plasticity;Behavioral Ecology;Evolutionary Ecology;Ecology and Evolutionary Biology;Science;Ecology and Evolutionary Biology