show Abstracthide Abstracttranscriptome-wide scan for single nucleotide polymorphisms (SNPs) with the 454 technology, performed in preparation for a large-scale study of the maintenance and dynamics of hybrid zones in the context of global climate change. This preliminary scan for genetic markers of adaptive differentiation (1) provides data on the extreme polymorphism of M. balthica, (2) outlines loci putatively indicative of local adaptation, and (3) offers ground for discussing cytonuclear disequilibrium among M. balthica populations.