Phylogeography of the tailed frog (Ascaphus truei) in British Columbia

The tailed frog (Ascaphus truei) is highly philopatric, with naturally disj unct populations. To infer the historical pattern of range expansion and co ntraction in A. truei of British Columbia (B.C.), we conducted a randomly a mplified polymorphic DNA (RAPD) survey, using 16 primers, of 469 individual s sampled from 22 populations in four regions. Genetic distances, based on 169 putative RAPD loci, clustered populations into three clear groups: mid/ north-coastal B.C., south-coastal B.C., and interior B.C. The interior popu lations were the most distinct group, but their genetic distance from other groups equals that expected from isolation by physical distance alone, as opposed to taxonomic differentiation. F-ST values within coastal regions we re moderately low (0.02-0.05) but were high in the interior (0.12) and acro ss all populations (0.18). Within the mid/north-coastal and south-coastal r egions, genetic distance showed no relationship with physical distance, whi le among regions and within the interior region there was a strong relation ship. Gene diversity varied significantly among regions, with both the inte rior and south-coastal populations showing about 25% less diversity than th e mid/north-coastal populations. These data indicate a complex history of g eographic restrictions to multiple refugia, followed by various types of ra nge expansion. The implications of these results for conservation efforts i n this species are discussed.