DISSERTATION RESEARCH: Inferring the Evolutionary History of Arthropods Associated with Pitcher Plants using Phylogeographic Concordance Factors.

Ohio State University, The, Columbus OH

Investigators

Abstract

Interactions among species are driving forces behind the formation, structure and existence of ecological communities. In these communities, species interact with one another, compete for resources, and ultimately shape the existence and distribution of biodiversity on Earth. A central question of evolutionary biology is how these ecological communities came to be, and how long these interactions have persisted. This research will provide a new tool for understanding if ecological communities have persisted over evolutionary time scales, and to what extent the co-occurring species show similar patterns in their genetic diversity. If ecological communities exhibit strong patterns of a shared evolutionary history, the extinction of a single member may be dire for other ecologically associated species. Understanding these attributes will provide insight into how species responded to the dynamic landscape and climatic changes during the Pleistocene ice ages, and will help conservation managers identify regions in need of protection. This research aims to develop phylogeographic concordance factors, a novel statistical approach testing for co-diversification in an ecological community. This synthesis will identify common diversification patterns across species as well as species that do not conform to these patterns. Phylogeographic concordance factors take in species tree distributions from multiple co-occurring species, and identify patterns shared among the clades. These clades are then used to construct a concordance tree, providing a phylogeny with support values that best represents diversification patterns of the community. Importantly, this method will identify species that are outliers of a dominant pattern. Along with developing the method as a package for the statistical platform R, this approach will be demonstrated in the Sarracenia alata carnivorous pitcher plant system. This system is located in the topographically and geologically complex region of the southeastern United States, where a number of previous studies have documented emergent biogeographic patterns. Mitochondrial data from five arthropods from this community indicate that genetic variation has been structured in a similar way to the host plant, but preliminary sequence data generated from the nuclear genome implies a more complex evolutionary history for this system, making the system ideal for studies using phylogeographic concordance factors. This new tool will enhance the ability of researchers to identify shared patterns of diversification, and the evolutionary processes that have influenced biodiversity.