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

    Research output: Contribution to conferencePaper/Powerpoint/Abstract

    190 Downloads (Pure)

    Abstract

    Gene flow and adaptive divergence are key aspects in 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. We expected that different habitats would contribute to strong divergence and restricted gene flow resulting in isolation-by-adaptation. Instead, we found remarkably high levels of effective long-distance seed dispersal and low levels of adaptive divergence. Depending on the studied region, at least 15.2 to 16.5% of the assigned individuals originated from among-population dispersal events with dispersal distances up to 220 km. Six (1.3%) ‘outlier’ loci, potentially reflecting local adaptation to habitat-type, were identified with high statistical support. Of these, only one (0.22%) was a replicated outlier in multiple independent dune-fen population comparisons and thus possibly reflecting truly parallel divergence. Signals of adaptation in response to habitat type were most evident at the scale of individual populations. These findings suggest that the homogenizing effect of effective long-distance seed dispersal may overwhelm divergent selection associated to habitat type in fen orchids in Northwest Europe.
    Original languageEnglish
    Number of pages22
    Publication statusPublished - 2014

    Thematic list

    • Species and biotopes

    EWI Biomedical sciences

    • B004-botany

    Taxonomic list

    • orchid family (Orchidaceae)

    Policy

    • biodiversity policy

    Geographic list

    • Europe

    Technological

    • genetic technologies
    • fieldwork (observations and sampling)

    Cite this