High levels of effective long-distance dispersal may blur ecotypic divergence in a rare terrestrial orchid

An Vanden Broeck, Wouter Van Landuyt, Karen Cox, Luc De Bruyn, Ralf Gyselings, Gerard Oostermeijer, Bertille Valentin, Gregor Bozic, Branko Dolinar, Zoltán Illyés, Joachim Mergeay

Gene flow and adaptive divergence are key aspects of metapopulation dynamics and ecological speciation. Long-distance dispersal is hard to detect and few studies estimate dispersal in combination with adaptive divergence. The aim of this study was to investigate effective long-distance dispersal and adaptive divergence in the fen orchid (Liparis loeselii (L.) Rich.). We used amplified fragment length polymorphism (AFLP)-based assignment tests to quantify effective long-distance dispersal at two different regions in Northwest Europe. In addition, genomic divergence between fen orchid populations occupying two distinguishable habitats, wet dune slacks and alkaline fens, was investigated by a genome scan approach at different spatial scales (continental, landscape and regional) and based on 451 AFLP loci.