PARENT SESSION
Oral Session #70: Invasive Species: Aquatic.
Presiding: S. Juliano
Wednesday, August 7. 1:00 PM to 4:45 PM. Grand Ballroom East, Radisson.
Multiple worldwide invasion pathways of a freshwater snail: The revenge of New Zealand.
Dybdahl, Mark*,1, 1 Washington State University, Pullman, WA, (dybdahl@wsu.edu)
ABSTRACT- The success of an invader may be determined by its genetic diversity, which should be enhanced if populations are founded by multiple invasions of different origin. I tracked the invasion pathways of a New Zealand endemic freshwater snail Potamopyrgus antipodarum to determine their origin and diversity worldwide. In New Zealand, this species is dioecious but females are either obligately sexual or clonal. Invasive populations (UK, Europe, Australia, Tasmania, Japan, and USA) are clonal, and often dominate benthic habitats. Individual introduced populations could result from single invasions, or multiple sequential invasions; the origins may be either New Zealand populations or introduced populations via steppingstone pathways. Snails were sampled from 19 introduced populations from the 6 major regions. These were compared to numerous sexual and clonal populations from the North and South Islands of New Zealand. Source-recipient relationships were traced using similarities in alleles or multilocus genotypes based on allozymes. This analysis shows that, in the UK and Europe, three distinct multilocus allozyme genotypes represent separate invasions from New Zealand, which concords with their distinct ecological ranges (UK rivers, Danish estuaries, and freshwaters elsewhere). In the USA, Lake Ontario (NY) is inhabited by the European freshwater clone, implying a steppingstone pathway. A different clone occurs across 4 disparate invasion areas in the western USA (ID, MT, OR, CA); it matches a genotype from Australia. Samples from Tasmania and Japan were monoclonal, and similar to North Island populations. Only Australian populations were comprised of diverse sets of clones. Thus, most individual introduced populations of Potamopyrgus have a single origin, and lack genetic diversity (monoclonal), but are apparently successful.
KEY WORDS: invasive species, invasiveness, genetic diversity, Potamopyrgus