Meeting Abstract

P1.11  Tuesday, Jan. 4  The Hybridization of Endemic and Alien Damselfish Species on Hawaiian Reefs KIMOKEO, Bethany K.*; GAITHER, Michelle; TOONEN, Robert J.; University of Hawaii, Manoa; Hawaii Institute of Marine Biology bkimokeo@hawaii.edu

There are 343 known alien species in Hawaiian waters, but with the exception of alien algae, most of these marine invaders are thought to have relatively little impact on native reefs. For example, the Pacific Sergeant Major, Abudefduf vaigiensis, appears to have colonized the Hawaiian archipelago in the early 1990s and co-schools with the endemic conspecific, Abudefduf abdominalis, but no decline is apparent in the native as a result of this invasion. Fish of intermediate color pattern led to speculation of hybridization, and recently a few cases of interspecific spawning have been observed. Interestingly, all such interspecific spawnings have been initiatied by a female A. vaigiensis with the male A. abdominalis remaining to fertilize, guard, and clean the hybrid clutch along with a previous clutch until the embryos hatched. The aim of the project is to use genetic techniques to determine: 1) whether the observed interpecific spawning was successful and the fertilized eggs are indeed hybrids, 2) the frequency of hybridization between A. abdominalis and A. vaigiensis among wild populations across the Hawaiian Archipelago, and 3) whether successful hybridization is asymmetric as suggested by spawning observations. To accomplish this goal, mitochondrial (cytochrome b) and nuclear DNA (S7, Gpd2 and GnRH introns) were analyzed for A. abdominalis (N=317) and A. vaigiensis (N=189) to infer the maternal and paternal species lineages for each individual. Among the 506 fish analyzed from 12 locations across the Hawaiian archipelago, to date, only two F1 hybrids have been identified, and both come from Maro Reef in the Northwestern Hawaiian Islands. Hybridization of the endemic A. abdominalis with the alien A. vaigiensis poses a potential threat to the persistence of the endemic species, but these data imply that the rate of hybridization is low.