Data from: Phylogeography of the highly dispersible landscape-dominant woody species complex, Metrosideros, in Hawaii

Aim: Little is known about how diversification occurs within long-lived,
highly dispersible and continuously distributed groups. We examined the
distribution of genetic variation within the woody genus Metrosideros
across the Hawaiian Islands for insights into how diversification occurs
within this animal-pollinated, wind-dispersed group. Among Hawaiian
plants, Metrosideros is unique in its formation of continuous stands
within islands that span a remarkable range of environments and comprise
numerous predominantly single-island taxa. Location: Hawaiian Islands
Taxon: Metrosideros Methods: We performed population genetic analyses of
variation at nine nuclear microsatellite loci from 1,486 adults of 23
Metrosideros morphotypes sampled from five main Hawaiian Islands plus
additional Pacific Island populations. Results: American Samoa and Tahiti
populations clustered most closely with the older islands. Results also
revealed isolation by distance across the archipelago, clustering of
populations predominantly by island, and evidence of multiple
colonizations or back-colonizations of three islands. The number of
genetic clusters peaked on islands of intermediate age, coincident with
peak morphotype richness. All islands comprised a broad range of genetic
distances among taxa with the greatest overall genetic distance observed
on Oahu. The two taxa that are distributed broadly across the archipelago
were weakly but significantly differentiated only on volcanically active
Hawaii Island, where they partition early- and late-successional
environments. One of these taxa was positioned centrally both within
individual-island splitstree networks and across the archipelago-wide
network. Main conclusions: Distance-dependent gene flow contributes to
isolation of Metrosideros across islands, especially on terminal islands.
Morphological diversity likely accumulates rapidly within this group,
likely associated with differential adaptation across heterogeneous
environments, but isolation of gene pools through speciation within
continuous Metrosideros stands likely requires persistent disruptive
selection where environments are stable for long periods. The generalist,
wet-forest M. p. v. glaberrima may play a central role in the generation
of the group's many, largely island-endemic, forms.