ZARDUS, J.D.*; HADFIELD, M.G.; University of Hawaii, Honolulu; University of Hawaii, Honolulu: Genetic comparisons between native Atlantic and invasive Pacific populations of the barnacle Chthamalus proteus.

The Atlantic Barnacle (Chthamalus proteus) is a recent invader of the Pacific, first found in Hawaii in 1993. Faunal surveys suggest it became established in Hawaii between 10 and 30 years ago; within the last decade it has been observed from several other widespread Pacific islands. We report on its geographic distribution and genetic variation within the Pacific. Genetic comparisons were made with a range of potential source populations in the Atlantic and the Caribbean and with all known populations in the Pacific. Sequencing a portion of the mitochondrial gene cytochrome oxidase subunit I, we applied phylogenetic methods to: 1) search for matches with source populations; 2) compare levels of genetic variability; and 3) determine genetic linkages among the Pacific localities. We found matches with several genetic stocks, indicating that introductions stem from multiple localities. The barnacle was found on nearly every major Hawaiian island, and its occurrence was confirmed in French Polynesia and Guam but not in Micronesia. Genetic diversity was very high within Hawaii, and haplotype distributions varied by locality within the Pacific. Patterns of genetic linkage and scenarios of introduction will be discussed.