Speciation and diversification in the North American tiger beetles of the cicindela sylvatica group: morphological variation and an ecophylogeographic approach.

Abstract

SPECIATION AND DIVERSIFICATION IN THE NORTH AMERICAN TIGER BEETLES OF THE CICINDELA SYLVATICA GROUP: MORPHOLOGICAL VARIATION AND AN ECOPHYLOGEOGRAPHIC APPROACH

DANIEL PAUL DURAN

Dissertation under the direction of Professors Daniel J. Funk (2004-2009) and Charles K. Singleton (2009-2010)

In this dissertation, I addressed three fundamental questions in evolutionary ecology: 1) What factors promote population differentiation and speciation? 2) What are the determinants of species ranges? and 3) What are the principal causes of phenotypic variation? I used multiple phylogenetic, population genetic, and coalescent-based molecular analyses in conjunction with GIS-based environmental niche modeling and statistical analyses of phenotypic characters to test hypotheses concerning the evolutionary history and ecology of a group of North American tiger beetles. Using a ‘congeneric phylogeography’ approach, I sampled intensively from all the nominal species and subspecies of the North American Cicindela sylvatica group. None of the nominal species were found to be monophyletic with respect to mtDNA. Analyses supported multiple underlying causes for the species-level polyphyly, including cases of polymorphism, hybridization, and incomplete lineage sorting. Abiotic factors were shown to be primarily limiting species distributions. These same environmental factors were also significantly predictive of color pattern variation in C. longilabris. This integrative multidisciplinary approach can serve as a model for future studies. Each series of investigations reciprocally informed the others, leading to a more robust set of conclusions about the causes of differentiation and speciation in these taxa. The results of this dissertation also have important consequences for systematic research in general, especially for the disciplines of molecular systematics or “molecular taxonomy” (Blaxter and Floyd 2003; Tautz et al. 2003; Blaxter 2004), and “DNA barcoding” (Hebert et al. 2003 a, b). In addition to these larger issues, there are more specific systematic and taxonomic implications for understanding the causes for the patterns of distribution of the North American Cicindela sylvatica group and consequences for future tiger beetle research.