Genetic variation for adaptive traits is associated with polymorphic inversions in <i>Littorina saxatilis</i>

Chromosomal inversions have long been recognized for their role in local adaptation. By suppressing recombination heterozygous individuals, they can maintain coadapted gene complexes and protect them from homogenizing effects of flow. However, to fully understand importance adaptation we need know influence on phenotypes under divergent selection. For this, the marine snail Littorina saxatilis provides an ideal study system. Divergent ecotypes adapted wave action crab predation occur close proximity intertidal shores with flow between them. Here, used F2 individuals obtained crosses test associations genomic regions traits distinguishing Crab-/Wave-adapted including size, shape, shell thickness, behavior. We show that most these are influenced by two previously detected inversion ecotypes. thus gain a better understanding one important underlying mechanism responsible rapid repeated formation ecotypes: selection acting inversions. also found some contributed more than trait suggesting may contain several loci involved adaptation, consistent hypothesis suppression within facilitates differentiation presence