The Role of Phylogenetic Relatedness and Diversity on Community Assembly and Ecosystem Functioning: Experimental Tests Using Laboratory Protist Microcosms

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Human activities, such as the conversion of forests into agricultural land, overexploitation of natural resources, environmental pollution, and the ever-increasing release of greenhouse gases into the atmosphere have resulted in tremendous biodiversity loss. Concerned over the possibility that the decline in biodiversity may reduce the ability of natural and managed ecosystems to provide products and services for humanity, ecologists have studied relationships between biodiversity and ecosystem functions (e.g., crop production). These studies have significantly improved our knowledge on the consequences of biodiversity loss. Nevertheless, the majority of these studies have focused on species diversity, that is, the number of species in an ecological community, and relatively little attention has been paid to other components of biodiversity. As a result, there is a significant gap in our knowledge on the consequences of the loss of biodiversity components other than species diversity. This project will explore the ability of phylogenetic diversity (PD), a component of biodiversity that accounts for species evolutionary relationships, for predicting the structure of ecological communities and the functions of ecosystems. This project will also provide high-quality research training for a postdoctoral fellow, and graduate and undergraduate students, particularly those from underrepresented groups. Using freshwater ciliated protists as model organisms, the proposed experiments will advance knowledge in four specific areas. First, it will link ecologically important traits and species niche and fitness differences in a phylogenetic context. Second, it will investigate mechanisms underlying phylogenetic diversity (PD)-ecosystem function relationships by testing the novel hypotheses that PD-ecosystem function relationships depend on how PD translates into species niche and fitness differences. Third, it will examine the role of the PD of the species pool in modulating the historical contingency of community assembly by linking PD with species niche and fitness differences. Fourth, it will provide a rigorous test of Darwin's naturalization hypothesis by examining both invader success and impact, with novel hypotheses informed by recent meta-analysis of existing empirical studies. Together, the proposed research marries phylogenetic ecology with contemporary species coexistence theory to gain a more mechanistic understanding of the role of PD for community assembly and ecosystem functioning.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.