Advancing a genealogical and systems-based theory of the evolution of biodiversity

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Diversity in nature is multivariate. Individuals differ from each other in more than one phenotypic trait, where a phenotypic trait is simply a measured physical and/or behavioural attribute of an individual. Differences among individuals and species in their multivariate phenotype determine, in part, differences in the niche they occupy. This idea of a multivariate niche traces back to a classic paper by Hutchinson in 1957. For example the pollination niche of a plant species is a function of its flowering time, flower color, flower symmetry, nectar production, pollen production, and flower number. The evolution of a species’ multivariate niche depends on several factors, including the physical attributes of the area the species occupies, the other species it interacts with and the genotypes of individuals that make up the species. Furthermore, there is evidence that ecosystem processes are determined, in part, by the multivariate phenotypes of species that compose a community. Using theoretical modeling, my lab studies how the evolutionary history of a species affects its multivariate diversity. We know from previous work that genealogical history can restrict multivariate diversity, but the mechanisms that can overcome this limit are not fully understood. Current work in my lab is exploring genetic mechanisms that can overcome this constraint, with a focus on epistatic gene-action. Epistatic gene-action occurs when mutations interact to produce a phenotype in a non-additive manner. Recent work in my lab studying asexual populations showed that epistatic gene-action reduces the constraint of genealogical structure on multivariate evolution. In this grant application we seek support to characterize how epistatic gene-action affects multivariate diversity in populations that undergo sexual reproduction and recombination. In addition, we seek to determine whether unique aspects of the meiotic process in polyploid species facilitate the evolution of multivariate diversity. Recent theoretical work indicates that ecological diversification is easier when it involves a multivariate versus a univariate trait. Here we seek to determine whether epistasis can further facilitate ecological diversification, which may be important for understanding the causes of speciation. The genealogical approach to modeling epistasis and multivariate trait evolution is technically complicated. As such, direct estimation of parameters in the model is difficult in natural settings. In this grant we seek to develop an indirect approach to estimate attributes of our model that would test whether epistatic gene-action in combination with genealogical structure is, in fact, important with respect to determining diversity in nature. Lastly, we seek to address the question of how multivariate diversity arises in the first place. Work in developmental biology indicates modular gene-action and gene duplication may facilitate the evolution of diversity. Recent empirical work suggests that gene duplications introduce new epistatic interactions. Here we seek to determine whether gene duplication in combination with epistatic gene-action facilitates the evolution of multivariate diversity.