CLONAL STRUCTURE OF THE INTRODUCED FRESH-WATER SNAIL POTAMOPYRGUS-ANTIPODARUM (PROSOBRANCHIA, HYDROBIIDAE), AS REVEALED BY DNA FINGERPRINTING

Multi-locus DNA fingerprints were obtained from individuals of the hydrobiid snail, Potamopyrgus antipodarum ( = P. jenkinsi), by using an RNA derivative (pSPT 18. 15) of Jeffreys's 33. 15 minisatellite core sequence. Whole-body homogenization of snails yielded 3.21 +/- 0.09-mu-g DNA per individual, producing complex profiles comprising 12-22 fragments within the 1.0-20.0 kilobase (kb) size range. Fingerprints from natural and experimental populations identified three distinct clonal genotypes corresponding to morphological strains A, B and C, with only rare mutational variants. Mother-offspring comparisons of genetic fingerprints revealed genetic stability during apomictic parthenogenesis. Data support the notion that British populations of P. antipodarum comprise three widespread obligate parthenogenetic clones resulting from a mid-19th Century introduction from Australasia. The present-day low levels of genotypic diversity are discussed in relation to the typical occurrence of P. antipodarum in man-made or immature habitats.