Data from: Persistent inter- and intraspecific gene exchange within a parallel radiation of caterpillar hunter beetles (Calosoma sp.) from the Galápagos

When environmental gradients are repeated on different islands within an
archipelago, similar selection pressures may act within each island,
resulting in the repeated occurrence of ecologically similar species on
each island. The evolution of ecotypes within such radiations may either
result from dispersal, that is each ecotype evolved once and dispersed to
different islands where it colonized its habitat, or through repeated and
parallel speciation within each island. However, it remains poorly
understood how gene flow during the divergence process may shape such
patterns. In the Galápagos islands, three phenotypically similar species
of the beetle genus Calosoma occur at higher elevations of different
islands, while lowlands are occupied by a fourth species. By genotyping
all major populations within this radiation for two nuclear and three
mitochondrial gene fragments and seven microsatellite markers, we found
strong support that the oldest divergence separates the highland species
of the oldest island from the remaining species. Despite their
morphological distinctness, highland species of the remaining islands were
genetically closely related to the lowland population on each island and
within the same magnitude as lowland populations sampled at different
islands. Repeated evolution of highland ecotypes out of the lowland
species appears the most likely scenario and estimates of geneflow rates
revealed extensive admixture among ecotypes within islands, as well as
between islands. These findings indicate that gene exchange among the
different populations and species may have shaped the phylogenetic
relationships and the repeated evolution of these ecotypes.