[Taxacom] We're on a road to nowhere

[John Grehan]

An illustrative example on the incoherence of dispersalist theory is the
nonsense about New Zealand's biota being totally adventive following
supposed drowning of the entire landmass in the Oligocene. According to
this doctrine there is no evidence of terrestrial landscapes (although
ignoring the fact that sedimentation was occurring that required
terrestrial land) and therefore it was self evidence that everything
dispersed over the ocean (mostly from Australia naturally.

As was noted in this list, it theoretically takes only one gravid
individual to make it happen. So, for a species I studied, a large ghost
moth (females about 150 mm wingspan) is supposed to have made the
distance even though a gravid female can barely fly at walking speed,
and with an abdomen so heavy that it hangs down almost vertically in
flight. The flight requires rapid wing speed to keep aloft so there is
no gliding involved. The female has no mouthparts and usually does not
survive the night. The eggs, which appear to be dropped constantly once
the moth starts to fly, have to be dropped over a landscape that has
near 100% humidity within a forest.

But all of that does not matter. I am supposed to take it as a matter of
faith to accept that at least one female made it Across the Tasman in
one of those easterly storms that are known to transport other moths,
and in such a way that only one ever made it since the Oligocene to
establish a new species in New Zealand. And amazingly enough to make it
also to New Caledonia (even though no other ghost moths made it -
including much smaller genera which are present in New Zealand and New
Guinea), but not to Fiji where another unique ghost moth occurs (that
has no obvious affinities recognized at present other than possibly with
some Australian and South American taxa), but not able to disperse
across the much smaller distances separated in Solomon Islands, or even
west between the Mollucas and Celebes or Timor.

Dispersal is fine in any one case as one may even believe that moa
ancestors swam across the Tasman or that the had volant ancestors that
flew, but once one starts examining the geographic details the result
sets up a series of nonsensical contradictions as evident for New
Zealand - never mind that many taxa in New Zealand still track the path
of Mesozoic and early Tertiary tectonics (a fact usually ignored by the
dispersalist theorists in New Zealand).

John Grehan