Data from: Gene flow and effective population sizes of the butterfly Maculinea alcon in a highly fragmented, anthropogenic landscape

Understanding connectivity among populations in fragmented landscapes is
of paramount importance in species conservation because it determines
their long-term viability and helps to identify and prioritize populations
to conserve. Rare and sedentary species are particularly vulnerable to
habitat fragmentation as they occupy narrow niches or restricted habitat
ranges. Here, we assess contemporary interpopulation connectedness of the
threatened, myrmecophilous butterfly, Maculinea alcon, in a highly
fragmented landscape. We inferred dispersal, effective population sizes,
genetic diversity and structure based on 14 locations of M. alcon in
Belgium and the Netherlands using data from 12 microsatellite loci.
Despite the reported sedentary behaviour of M. alcon, we observed moderate
levels of contemporary dispersal between patches, but only in landscapes
where populations were located within a distance of 3 km from neighbouring
populations. Estimates of effective population sizes (Ne) were very low
(ranging from 1.6 to 17.6) and bottleneck events occurred in most of the
studied populations. We discuss the functional conservation units
delineated based on a former mark-release-recapture study, and formulate
appropriate conservation strategies to maintain viable (meta)populations
in highly fragmented, anthropogenic landscapes.