INTRASPECIFIC MITOCHONDRIAL-DNA VARIATION IN THE COLORADO POTATO BEETLE, LEPTINOTARSA-DECEMLINEATA (COLEOPTERA, CHRYSOMELIDAE)

Restriction endonuclease analyses of mitochondrial DNA (mtDNA) were us ed to examine genetic variability and population structure in Leptinot arsa decemlineata (Say). A group of three enzymes, EcoRI, HpaI, and Ps tI, was used to reveal polymorphism both within and among some of the 10 populations tested yielding 16 haplotypes in combination. The frequ encies of these 16 haplotypes differed significantly across geographic regions, indicating some partitioning of mtDNA haplotypes. Estimates of mtDNA sequence divergence (delta) between haplotypes ranged from 0. 016 to 0.135%, suggesting local differentiation of mtDNA in some popul ations. Analysis of these data suggests that Texas was colonized by mo re than one mtDNA lineage, most likely originating in Mexico. We hypot hesize that a larger founder size for the initial introductions or hig h levels of variability in the parent population at the edge of the CP B expanding range led to the initial partitioning of haplotypes observ ed in samples from Texas.