Genetic differentiation and local adaptation in the salt-marsh beetle Pogonus chalceus: a comparison between allozyme and microsatellite loci.

The genetic structure of Pogonus chalceus from 11 Atlantic and seven Mediterranean Western European populations was analysed. Results from seven allozyme loci were compared to five microsatellites to test the hypothesis that some enzymatic loci undergo selection. Both allozyme and microsatellite results showed that Mediterranean beetle populations are genetically distinct from Atlantic populations. The analysis of the genetic structure showed that FST values derived from all microsatellite loci were much smaller than those obtained from allozymes. The enzymatic locus Idh-1 exhibited a high value compared to the other loci, suggesting that it is non-neutral. The same Idh-1 locus was implicated in differentiation between temporary and stable populations, as followed also from a highly significant relationship between the allele two of this Idh-1 locus and dispersal power population estimates. The 'parallel evolution' model may account for the diversification of locally adapted Pogonus chalceus populations between different microhabitats.