PHYLOGEOGRAPHIC PATTERNS IN COASTAL NORTH-AMERICAN TIGER BEETLES (CICINDELA-DORSALIS SAY) INFERRED FROM MITOCHONDRIAL-DNA SEQUENCES

Genetic variation was assessed in the tiger beetle, Cicindela dorsalis, by sequencing of three regions of the mtDNA genome. Populations of four morphologically distinguishable subspecies were sampled from 28 representative locations covering almost the entire geographic range of the species in coastal North America. In 78 individuals analyzed for 656 base pairs from four different genes, 17 different haplotypes could be distinguished. A cladistic analysis grouped the haplotype sequences into two main lineages, one from the Atlantic Ocean and one from the Gulf of Mexico. Haplotypes within the two clades were very similar to each other. Most of the characters that distinguished these closely related haplotypes were homoplastic. The geographic distribution of haplotypes did not coincide with the distribution of morphological subspecies, but no evidence for hybridization between two subspecies could be inferred from this observation. The implications of these findings for the evolution of gene sequences at and below the species level are discussed.