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.

Patterns of Mating‐system Evolution in Hermaphroditic Animals: Correlations Among Selfing Rate, Inbreeding Depression, and the Timing of Reproduction

“…In P. gyrina , the F is is actually based on very little information: the product of the sample size by number of loci by average genetic diversity is 8.42 (Buth and Suloway 1983), meaning that heterozygote deficiency is computed on the basis of eight expected observations in total. In S. putris , the authors (Jordaens et al 2006) found a large variance in F is among loci and concluded that the F is observed are inflated by other causes than selfing, which is consistent with the fact that selfed offspring practically never survive ( AID is 0.97).…”

Heavy Metal Pollution as a Biodiversity Threat

“…Some examples are: Peromyscus melanophrys: As, Pb, Cd, Cu, Zn [7], Cognettia sphagnetorum: Cu [45]; Talitrus saltator: Cd, Hg, Cu, [46]; Pachygrapsus marmoratus: As, Pb, Cd, Co [47]; Ficedula hypoleuca: Cd, Zn, Pb, Cu, Ni, Al, As, Cr, Se [48]. In contrast, an increase in genetic diversity levels in 36.4% of the analyzed species was found, like Lumbricus rubellus: Cd, Zn, Cu, Pb [49]; Cepaea nemoralis: Cd, Cr, Cu, Ni, Pb, Zn [50]; Parus major: Cd, Zn, Cu, Pb, Ni, Al, As, Cr, Sn [48] and Larus argentatus (steel), [51]. Meanwhile, the remaining 18.2% of the studied species did not register changes in genetic diversity levels, such as: Apodemos sylvaticus: Cd, Zn, Cu, Pb, Ni, Al, Ag, As, Co, Mn, Fe [42] and Succinea putris: Cd, Cr, Cu, Ni, Pb, Zn [50].…”

Investigations of responses to metal pollution in land snail populations (Cantareus aspersus and Cepaea nemoralis) from a smelter-impacted area

“…Notably, they showed variations in Pb accumulation in soft tissues, differences in Pb distribution among body and shell, and different patterns of interactions in the metabolism of Pb and Ca (Beeby and Richmond 1988, 2001aMulvey et al 1996). Studying genetic variations in the land snails Cepaea nemoralis and Succinea putris between unpolluted and metal-polluted sites, Jordaens et al (2006a) did not find significant evidence of adaptation to local pollution. Such discrepancies between studied species and metals highlight the need to develop metal-adaptation studies in land snail populations, and investigate differential species responses to metal pollution.…”

“…To tackle those questions, two main types of studies are carried out: genetics (studying the genetic structure of populations, gene expression, mutations, transcriptional regulation…), or comparison of offspring responses (metal accumulation, growth, life-history traits, etc.) of populations originating from control and polluted sites in cross-transplantation experiments Belfiore and Anderson 1998;Jordaens et al 2006a;Roelofs et al 2009;Rozen 2006). Adaptation to metal-polluted environments has been studied in numerous taxa including fungi, bacteria, plants, aquatic organisms, soil invertebrates, insects and arachnids (Kammenga and Laskowski 2000;Morgan et al 2007;Posthuma and van Straalen 1993).…”