Jeffrey Oliver PhD Candidate Insect Science-GIDP 2007 Pacific Branch Entomological Society of America 91st Annual Meeting PACIFIC ENTOMOLOGY: PIONEERING NEW TRAILS! Meeting Portland Marriott Downtown Waterfront, Portland, OR March 25-28, 2007

ABSTRACT
Traditional phylogeographic approaches may sometimes reveal unexpected patterns of genetic variation, indicating previously unknown evolutionary history. Genetic analyses of Lycaena xanthoides(Lepidoptera: Lycaenidae), the Great Copper Butterfly, demonstrate two previously unrecognized, predominantly allopatric lineages. Using standard population genetic techniques, as well as a new parametric bootstrapping method, I investigated the processes underlying this genetic divergence. Analyses of molecular variance indicate significant genetic differentiation between the southern and northern populations of L. xanthoides, and post­hoc morphometric analyses also indicate significant morphological differentiation between the two lineages of L. xanthoides. Finally, I performed simulations in Mesquite to test hypothetical scenarios of isolation between these two lineages. The results indicate the pattern of isolation could be explained by vicariance, occurring approximately 1 million years ago. The barrier to gene flow was likely the Transverse Ranges of southern California, which served as isolating barriers to at least two other two other lepidopteran taxa. This study affirms the impact of the Transverse Ranges on genetic isolation of southern Californian arthropod taxa, and demonstrates the utility of simulation studies in phylogeographical hypothesis testing.