[Taxacom] tectonic correlation

[John Grehan]

Just an additional comment which I did not have time to make earlier. The
paper describes an example case involving two taxa that show a pattern of
distribution involving New Caledonia and the northern North Island of New
Zealand. One is the plant family Xeronemataceae present only in New
Caledonia and a couple of offshore islands of the North Island. The other
is a clade of wetas (flightless crickets) in New Caledonia and only in the
northern North Island across a region that is characterized by some
allochthonous geological terranes that run in parallel with the Vening
Meinesz tranform margin and an extinct subduction zone. This belt forms the
southern extension of the Loyalty (New
Caledonia) -Three Kings (New Zealand) arc.

The NI terranes are thought to have formed in Cretaceous-Oligocene time and
were transferred to mainland New Zealand during the Oligocene. So this
provides a nice example of tectonic correlation and indicates an Oligocene
age for the distributions of these taxa within New Zealand. There are many
other taxa that are also correlated with this tectonic pattern. A chance
dispersal model, which was proposed by Gibbs, is not necessary to
understand this distribution, and a chance dispersal migration from NC is
contradictory to the tectonically restricted distributions within NZ. Thus,
one may wish to believe in chance dispersal, but the biogeography does not
require it.

John Grehan