title: Genetic variation in two land snails, Cepaea nemoralis and Succinea putris (Gastropoda, Pulmonata), from sites differing in heavy metal content.
abstract: Allozyme variation was determined in two land snail species (Cepaea nemoralis and Succinea putris) from four localities in northern Belgium. In each locality we selected a polluted and a nearby, less-polluted, reference plot. We examined whether (i) genetic variability differed between the polluted and reference plots, (ii) populations from polluted plots experienced recent bottlenecks, and (iii) certain allele or genotype frequencies were associated with the pollution. Our results suggest that (i) about 13% of the genetic differentiation in C. nemoralis and 5% in S. putris was due to differences among polluted and reference plots, (ii) polluted and reference plots had comparable levels of genetic variation, but in C. nemoralis observed heterozygosities were higher in polluted plots, (iii) most plots showed significant evidence for recent bottlenecks, irrespective of the degree of pollution, so that bottlenecks seem poor indicators of pollution-induced stress in land snails, and (iv) mutagenic or pollution-induced modifications did not seem to account for new allozyme variants in polluted sites. The observed patterns of genetic variation may be explained by the action of genetic drift, pollution-mediated selection, restricted gene flow, or a combination of these processes.
authors.affiliation: Department of Biology, Evolutionary Biology Group, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium. kurt.jordaens@ua.ac.be
authors.forename: Kurt
authors.initials: K
authors.lastname: Jordaens
authors.forename: Hans
authors.initials: H
authors.lastname: De Wolf
authors.forename: Natalie
authors.initials: N
authors.lastname: Van Houtte
authors.forename: Bart
authors.initials: B
authors.lastname: Vandecasteele
authors.forename: Thierry
authors.initials: T
authors.lastname: Backeljau
mesh_terms: D000483:Alleles; D000818:Animals; D001530:Belgium; D004785:Environmental Pollutants / Q000633:toxicity; D019143:Evolution, Molecular; D051456:Gene Flow; D040961:Genetic Drift; D014644:Genetic Variation; D005828:Genetics, Population; D007527:Isoenzymes / Q000235:genetics; D019216:Metals, Heavy / Q000633:toxicity; D012641:Selection, Genetic; D012908:Snails / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D013045:Species Specificity
chemical_list: D004785:Environmental Pollutants; D007527:Isoenzymes; D019216:Metals, Heavy