[Taxacom] Metapopulation vicariance paper

John Grehan calabar.john at gmail.com
Tue May 16 19:24:02 CDT 2017

Happy to send a copy of the following article to anyone interested.

John Grehan

Michael Heads 2017. Metapopulation vicariance explains old endemics on
young volcanic islands. Cladistics (2017) 1–20


Terrestrial plants and animals on oceanic islands occupy zones of volcanism
found at intraplate localities and along island arcs at subduction zones.
The organisms often survive as metapopulations, or populations of separate
sub-populations connected by dispersal. Although the individual islands and
their local subpopulations are ephemeral and unstable, the ecosystem
dynamism enables metapopulations to persist in a region, more or less in
situ, for periods of up to tens of millions of years. As well as surviving
on systems of young volcanic islands, metapopulations can also evolve
there; tectonic changes can break up widespread insular metapopulations and
produce endemics restricted to fewer islands or even a single island. These
processes explain the presence of old endemic clades on young islands,
which is often reported in molecular clock studies, and the many
distribution patterns in island life that are spatially correlated with
tectonic features. Metapopulations can be ruptured by sea floor subsidence,
and this occurs with volcanic loading in zones of active volcanism and with
sea floor cooling following its production at mid-ocean ridges.
Metapopulation vicariance will also result if an active zone of volcanism
is rifted apart. This can be caused by the migration of an arc (by slab
rollback) away from a continent or from another subduction zone, by the
offset of an arc at transform faults and by sea floor spreading at
mid-ocean ridges. These mechanisms are illustrated with examples from
islands in the Caribbean and the Pacific. Endemism on oceanic islands has
usually been attributed to chance, long-distance dispersal, but the
processes discussed here will generate endemism on young volcanic islands
by vicariance.

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