Meeting Abstract

P2.199  Saturday, Jan. 5  Examining Genetic Diversity of an Invasive Colonial Ascidian in Southeast Alaska CLANCY, D.L.*; DAVIS, T.; RUIZ, G.; COHEN, C.S.; San Francisco State Univ; Alaska Department of Fish and Game; Smithsonian Environmental Research Center, Edgewater, MD; San Francisco State Univ darragh@sfsu.edu

In 2010, an isolated population of the invasive colonial ascidian, Didemnum vexillum, was discovered during a Bioblitz survey in Whiting Harbor, Alaska. Believed to be native to Japan, D. vexillum has now been reported in Europe, New Zealand and North America. As D. vexillum is an aggressive invader, and many communities in Alaska depend on their relatively pristine natural environment for economic and cultural practices, this invasion has become a significant cause for concern. Examining the possible pathways of D. vexillum to Whiting Harbor will allow us to learn how D. vexillum spreads and possibly how future invasions can be prevented. In order to characterize this invasion, we sampled the Whiting Harbor population, and compared it to other studies of D. vexillum populations around the world. We genotyped 31 specimens from around Whiting Harbor at a 586-bp fragment of the mitochondrial cytochrome oxidase subunit I (COI). We found three haplotypes with a haplotype diversity of 0.5720±0.0453. When compared to previously reported haplotype diversities of other locations around the Pacific ocean, where D. vexillum originated, we find it is lower than Japan and the western coast of North America (first reported in 1993), but higher than the population in New Zealand (2001). It is expected that an older invasion would have higher diversity than a newer one because it has had more time for continued or diversely sourced inoculations. Possible explanations for why the newer Alaska invasion has a higher diversity than New Zealand are having a higher rate of repeated invasions, or having established earlier than first detected. To better understand the source population(s) of D. vexillum in Alaska, we are investigating further with comparisons using nuclear loci.