Copper tolerance and genetic diversity of Porcellionides sexfasciatus (ISOPODA) in a highly contaminated mine habitat.

Organisms inhabiting metal-contaminated areas may develop metal tolerance, with either phenotypic adjustments or genetic changes (adaptation) or with both. In the present study, three populations of the terrestrial isopod Porcellionides sexfasciatus, collected at an abandoned mine area, were compared to assess the effects of metal contamination on tolerance to lethal and sublethal levels of copper, through comparison of survival, avoidance, and feeding. The effects of metal contamination on genetic diversity were considered using random amplified polymorphic DNA (RAPD) markers. No evidence of increased metal tolerance of the population inhabiting the contaminated site was found. There was no correlation between metal exposure and within-population genetic variance, but the three populations were clearly separated from each other. In conclusion, the populations of P. sexfasciatus in the mine landscape live rather isolated from each other and show no differential tolerance to Cu or indications of genetic erosion. Their phenotypic plasticity provides a means to survive despite exposure to extremely high metal concentrations in the soil.