Data from: Metapopulation vicariance, age of island taxa and dispersal: a case study using the pacific plant genus Planchonella (Sapotaceae)

Oceanic islands originate from volcanism or tectonic activity without
connections to continental landmasses, are colonized by organisms, and
eventually vanish due to erosion and subsidence. Colonization of oceanic
islands occurs through long-distance dispersals or metapopulation
vicariance, the latter resulting in lineages being older than the islands
they inhabit. If metapopulation vicariance is valid, island ages cannot be
reliably used to provide maximum age constraints for molecular dating. We
explore the relationships between the ages of members of a widespread
plant genus (Planchonella, Sapotaceae) and their host islands across the
Pacific to test various assumptions of dispersal and metapopulation
vicariance. We sampled three nuclear DNA markers from 156 accessions
representing some 100 Sapotaceae taxa, and analyzed these in BEAST with a
relaxed clock to estimate divergence times and with a phylogeographic
diffusion model to estimate range expansions over time. The phylogeny was
calibrated with a secondary point (the root) and fossils from New Zealand.
The dated phylogeny reveals that the ages of Planchonella species are, in
most cases, consistent with the ages of the islands they inhabit.
Planchonella is inferred to have originated in the Sahul Shelf region, to
which it back-dispersed multiple times. Fiji has been an important source
for range expansion in the Pacific for the past 23 myr. Our analyses
reject metapopulation vicariance in all cases tested, including between
oceanic islands, evolution of an endemic Fiji–Vanuatu flora, and westward
rollback vicariance between Vanuatu and the Loyalty Islands. Repeated
dispersal is the only mechanism able to explain the empirical data. The
longest (8900 km) identified dispersal is between Palau in the Pacific and
the Seychelles in the Indian Ocean, estimated at 2.2 Ma (0.4–4.8 Ma). The
first split in a Hawaiian lineage (P. sandwicensis) matches the age of
Necker Island (11.0 Ma), when its ancestor diverged into two species that
are distinguished by purple and yellow fruits. Subsequent establishment
across the Hawaiian archipelago supports, in part, progression rule
colonization. In summary, we found no explanatory power in metapopulation
vicariance and conclude that Planchonella has expanded its range across
the Pacific by long-distance dispersal. We contend that this will be seen
in many other groups when analyzed in detail.