摘要
Identifying the causes of diversification is central to evolutionary biology. The ecological theory of adaptive diversi- fication holds that the evolution of phenotypic differences between populations and species--and the formation of new spe- cies-stems from divergent natural selection, often arising from competitive interactions. Although increasing evidence suggests that phenotypic plasticity can facilitate this process, it is not generally appreciated that competitively mediated selection often also provides ideal conditions for phenotypic plasticity to evolve in the first place. Here, we discuss how competition plays at least two key roles in adaptive diversification depending on its pattern. First, heterogenous competition initially generates heterogeneity in resource use that favors adaptive plasticity in the form of ＂inducible competitors＂. Second, once such competitively induced plas- ticity evolves, its capacity to rapidly generate phenotypic variation and expose phenotypes to alternate selective regimes allows populations to respond readily to selection favoring diversification, as may occur when competition generates steady diversifying selection that permanently drives the evolutionary divergence of populations that use different resources. Thus, competition plays two important roles in adaptive diversification---one well-known and the other only now emerging--mediated through its effect on the evolution ofphenotypic plasticity
基金
Acknowledgements We thank Zhi-Yun Jia for inviting us to submit this paper to a special column on phenotypic plasticity. Three anonymous reviewers provided valuable commentary that encouraged us to improve this work. We also wish to ac- knowledge the long term funding for plasticity research pro- vided by the U.S. National Science Foundation to DP, and the Natural Sciences and Engineering Research Council of Can- ada to BR. Finally, collaboration on this specific project was directly supported through a short-term fellowship to BR by the National Evolutionary Synthesis Center （NESCent
funded by NSF #EF-0905606）.
