[Taxacom] ant biogeography

[John Grehan]

Hi Brendon,

Below some comments on excerpts of your 2017 ant paper.


“The distinctive ant genus Leptomyrmex Mayr, 1862 had been thought to be
endemic to Australasia for over 150 years...The present study responds to a
recent and surprising discovery of extant  Leptomyrmex species in Brazil
with a thorough evaluation of the Dominican Republic fossil material, which
dates to the Miocene.”

Why surprising? Biogeographically there is nothing suprising at all. There
are innumerable 'Australiasia' (to greater or lesser extent) – South
America relationships. Very oridinary really.

“Fossils are essential for identifying former distributions of living and
extinct lineages, and are especially important in reconstructing the
biogeographic history of taxa that now occupy only relictual distributions.”

All living taxa are in some sense 'relictual”. In general, fossils appear
to be no more essential to the biogeography than living taxa. They are
complimentary elements. Fossils, like new living records, can also add to
what is already known.

“Early branching termites, for example, were thought to occur only in
Australia on the basis of extant fauna until numerous specimens were
recovered from present-day Neotropical and Palearctic fossil deposits”

If living taxa were collected from these latter regions this would also
have the same effect of expanding the known range

“Other examples of fossils rewriting history include a lineage of
dragonflies limited to Africa and Australia today but present as fossil
species from Europe and South America”

I would have to read the papers to see what kind of 'history' was being
'rewritten' but the expanded range is entirely normal. Perhaps of most
biogeographic interest would be whether the S America group is more closely
related to Africa or Australia.

“modern Ginkgo trees occurring in present-day China but distributed
throughout the northern hemisphere as recently as the Eocene”

No rewriting of 'history' required for this.