Abstract
Cicindela dorsalis dorsalis Say has been listed as an endangered insect species. As part of ongoing research and restoration efforts, we investigated the levels of genetic variation in this species. The polymerase chain reaction was used to amplify and subsequently sequence 25,000 base pairs of mitochondrial DNA from 32 individuals of C. d. dorsalis and several related species and subspecies. In addition to the mtDNA data, allozyme variation in 11 clearly resolvable nuclear biochemical loci was studied and analyzed separately within populations, between populations, and between subspecies. Levels of genetic variation within a geographically isolated relict population (Martha's Vineyard, MA), as well as within an undisturbed population (Chesapeake Bay, MD), were very low, indicating that even historically these beetles were genetically depauperate, presumably as a result of frequent natural extinctions of local populations. Phylogenetic reconstruction using DNA sequences placed two remaining populations of C. d. dorsalis in evolutionarily distinct units. We also examined whether genetic distance can be used as an indicator of the taxonomic status of C. d. media Le Conte, the subspecies most closely related to C. d. dorsalis. The amount of sequence divergence between C. d. dorsalis and C. d. media was similar to the levels observed between species of the Cicindela puritana Le Conte group that were used as a reference for the minimal amount of sequence divergence between closely related species. These molecular techniques can provide information on the population structure and subdivision, the evolutionary history of the species, and the phylogenetic framework (used as basis for taxonomic decisions), which in many cases cannot be obtained in any other way. We also propose that C. d. dorsalis can be used as a model system for conservation genetics.
Published Version
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