ALLOZYME AND MORPHOLOGY EVOLUTION IN EUROPEAN VIVIPARIDAE (MOLLUSCA, GASTROPODA, ARCHITAENIOGLOSSA)

The paper describes morphometric and allozymic differences among four European species of the family Viviparidae: Viviparus contectus (Mille t, 1813), V. viviparus (Linnaeus; 1758), V. acerosus Bourguignat, 1862 and V. ater (Cristofori et Jan, 1832). Fourteen continuous biometrica l characters were measured. Incremental discriminant-function analysis , principal-component analysis, and non-metric multidimensional scalin g were applied to analysis of the morphometric differences. All the te chniques confirmed a similar picture: a slight morphometric differenti ation, with the variability ranges of the species overlapping. On the other hand, the allozymic differentiation, studied at 12 loci, eight o f them intra and/or interspecific polymorphic; is much better marked, the intraspecific Nei's distances among the four V. contectus populati ons ranging from 0.0014 to 0.0397 mean 0.0166, and interspecific dista nces ranging from 0.2306 (V. ater-V. acerosus) to 0.9888 (V. contectus 2 and V. viviparus), mean 0.6871. The allele frequencies and genetic distances (Nei's distance and Cavalli-Sforza and Edwards' chord distan ce) were used to compute maximum likelihood, additive Fitch-Margoliash and ultrametric Fitch-Margoliash trees. All the trees presented a sim ilar pattern, but the maximum-likelihood and additive trees, based on Cavalli-Sforza and Edwards' distance, seem to reflect the phylogeny be st. The results are compared with the most parsimonious phylogenies in ferred for radular, soft-part morphology and anatomy, and opercular da ta from other papers by us, and the inferred phylogenies are also comp ared. Although the inferred molecular and morphological phylogenies ar e little different in topology, the amount of evolution along the corr esponding branches (measured as the number of changes averaged over al l reconstructions) is very different, the value of correlation coeffic ient between the two phylogenies being statistically insignificant. Th e occurrence of interspecific hybrids is discussed, and the isolation- by-competition mechanism is postulated. The probable origin of V. vivi parus from a founder population extremely restricted in number is stre ssed. The possible history of the group is briefly discussed. The spec ies is suggested to have originated in an unusual habitat of melt wate r at a glacier foreland that could have promoted genotypic differentia tion and sympatric speciation.