Effects of environmental pollution on microsatellite DNA diversity in wood mouse (Apodemus sylvaticus) populations

Abstract

Ten microsatellite DNA loci were surveyed to investigate the effects of heavy metal pollution on the genetic diversity and population genetic structure of seven wood mouse (Apodemus sylvaticus) populations along a heavy metal pollution gradient away from a nonferrous smelter in the south of Antwerp (Flanders, Belgium). Analysis of soil heavy metal concentrations showed that soil Ag, As, Cd, Cu, and Pb decreased with increasing distance from the smelter. Genetic analyses revealed high levels of genetic variation in all populations, but populations from the most polluted sites in the gradient did not differ from those of less-polluted sites in terms of mean observed and expected heterozygosity level and mean allelic richness. No correlation was found between measures of genetic diversity and the degree of heavy metal pollution. However, an analysis of molecular variance and a neighbor-joining tree suggested a contamination-related pattern of genetic structuring between the most polluted and less polluted sites. Pairwise F(ST) values indicated that populations were significantly genetically differentiated, and assignment tests and direct estimates of recent migration rates suggested restricted gene flow among populations. Additionally, genetic differentiation increased significantly with geographical distance, which is consistent with an isolation-by-distance model. We conclude that, at least for our microsatellite DNA markers, genetic diversity in the studied wood mouse populations is not affected greatly by the heavy metal pollution.

Effects of acid mine drainage on the genetic diversity and structure of a natural population of Daphnia longispina

“…This could indicate that metal contamination acted as a directional selective pressure to change gene frequencies in the exposed population (site I) relative to the references, but this change in frequencies was not reflected by a loss of genetic diversity. These results are in agreement with some of the mentioned studies, which also found that the genetic differentiation between populations of fish (McMillan et al, 2006;Mulvey et al, 2002Mulvey et al, , 2003Roark et al, 2005) and wood-mouse (Berckmoes et al, 2005) was more correlated with environmental contamination than with geographical distance and that these changes reflected selection by contaminants (Ownby et al, 2002).…”

“…Even though the reduction of genetic diversity in populations inhabiting contaminated areas has been reported in several aquatic and terrestrial species (Belfiore and Anderson, 2001;Bickham et al, 2000), recent studies employing either modern molecular methodologies, such as AFLP analysis (McMillan et al, 2006), microsatellite analysis (Berckmoes et al, 2005) and mitochondrial gene sequencing (Mulvey et al, 2003), or more classical methods, especially allozyme analysis Roark et al, 2005) have found little or no evidence for this effect. Nevertheless, this possible effect is one of the major concerns of modern conservation biology and ecotoxicology (Bagley et al, 2002;van Straalen and Timmermans, 2002).…”

Genetic variation, inbreeding and chemical exposure—combined effects in wildlife and critical considerations for ecotoxicology

“…The probability of DNA damage being converted into a permanent and/or heritable sequence alteration depends on the type of damage, the repair pathway recruited, the rate of repair and the fidelity and completeness of repair (Preston & Hoffman 2001). In some instances, mutagenic chemicals have been shown to increase genetic variation (albeit at neutral markers) (Chen et al 2003;Berckmoes et al 2005;Eeva et al 2006), but in other cases, to reduce it. This reduction can have negative impacts on wildlife by increasing the frequency of deleterious mutations that are selected against, causing bottlenecks, impairing gene flow (reviewed in Van Straalen & Timmermans 2002) and, less dramatically, lead to cumulative erosion of reproductive fitness (reviewed in Bickham et al 2000).…”

Heavy Metal Pollution as a Biodiversity Threat

“…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].…”

“…In both cases, these responses are the consequence of the adaptation of the population to polluted environments [3,[41][42][43][44].…”