Adaptation is expected to evolve faster on artificially polluted sites, but with large differences observed between taxa (Ernst ).
Hence, the evolution of metal tolerance on anthropogenic contaminated soils has been extensively studied for more than half a century to better understand plant adaptation to restrictive environments over ecological times (Antonovics et al. Plants occurring on metal contaminated soils usually belong to pseudometallophyte species developing both metallicolous (M, on metal-enriched soils) and non-metallicolous populations (NM, on non-polluted soils; Lambinon and Auquier ).
The specific aims of this study were to i) assess the genetic variability of , ii) compare patterns of genetic diversity among populations growing on recent (anthropogenic) and ancient (natural) habitats to test for a reduction in genetic variability after colonization of polluted areas, and iii) evaluate a demographic scenario and the timing of divergence between M and NM populations.
Populations clustered into two groups which corresponded to their edaphic origin and diverged 1,200 generations ago.
We detected a significant decrease in genetic diversity and evidence for a recent bottleneck in metallicolous populations.
Pseudometallophytes are model organisms for adaptation and population differentiation because they persist in contrasting edaphic conditions of metalliferous and non-metalliferous habitats.
We examine patterns of genetic divergence and local adaptation of in Poland and analyzed respective soil metal concentrations.
Additional factors that could influence the overall level of genetic diversity should be considered, including i) the age of polluted sites, ii) the level of soil metal concentration and associated selective pressure, iii) the level of genetic connectivity between M and NM populations, iv) the possibility of successive colonization events from adjacent NM populations, and v) some species-specific features such as clonal growth, sensitivity to abiotic stress, and constitutive (i.e.
species wide) or population-specific metal tolerance (Bickham et al. So far it has remained largely unclear whether historical, ecological or biogeographic factors could influence the pattern of genetic structure among M and NM populations of pseudometallophytes (Ye et al. Mining and processing of rich zinc-lead (Zn-Pb) ore in the Bolesław - Olkusz region (Cracow - Silesian Upland) dating back to the 13th century has created some of the largest and most polluted anthropogenic metalliferous sites in Europe, with waste heaps and dust deposits of different age, composition and metal concentrations (Cabala et al.Firstly, local adaptation to metal-polluted soils is expected to result in a higher frequency of tolerant genotypes in M compared to NM populations. Secondly, considering that M populations of pseudometallophyte species occurring on anthropogenic polluted sites result from recent colonization and adaptation events, their level of neutral genetic diversity is expected to be reduced due to selection, founder and bottleneck effects during the colonization of metalliferous soils (Lefèbvre and Vernet ).Accordingly, several phenotyping experiments reported higher mean metal tolerance levels in M compared to NM populations (e.g. Such contrasting patterns suggest that a simple comparison of edaphic types may not be sufficient to understand the structure of genetic diversity within and among populations of pseudometallophyte species.As a result, the distribution of such species is highly disjunctive and the closest NM populations are located ~100 km away in the Tatra Mts.Under such circumstances, lowland M populations may either result from long distance dispersal (LDD) events postdating pollution or represent relic populations from a formerly larger distribution range prior to the Last Glacial Maximum (LGM).For genotyping we used nine nuclear microsatellite loci.