Meeting Abstract

96.2  Thursday, Jan. 7  Can functional complexity mitigate performance trade-offs? An evolutionary analysis HOLZMAN, R*; COLLAR, DC; MEHTA, RS; WAINWRIGHT, PC; UC Davis; Harvard; UC Davis; UC Davis raholzman@ucdavis.edu

The parts of organisms (genes, molecules, and anatomical structures) typically participate in multiple organismal functions. Multiple roles bring about trade-offs because changes to individual traits that benefit one function often impose a cost to a second function. Through this mechanism, functional trade-offs are thought to have strong stabilizing effects on the evolution of organismal performance. Here we put forward and test the hypothesis that in complex systems, performance costs that result from competing demands on one trait are mitigated by independent, compensatory changes in other traits. We use the mechanism of prey capture in fishes to show how complex performance traits allow adaptive evolution to proceed without steep costs to other functions and thereby mitigate the constraining effects of trade-offs. This mechanism permits simultaneous enhancements in feeding performance on prey types that otherwise impose competing functional demands on the fish skull. We further show that the severity of trade-offs between performance traits is affected not only by the number of components that determine performance (i.e. complexity) but also by the evolutionary correlations between components (i.e. integration). Whereas complexity mitigates evolutionary trade-offs, evolutionary correlations between traits limit this effect. Complexity is therefore expected to promote morphological and ecological diversification by mitigating the constraining effects of trade-offs.