'Place' and evolution

Robert Mesibov mesibov at SOUTHCOM.COM.AU
Thu Feb 14 10:36:13 CST 2002

Les Kaufman wrote:

'The study of phylogeography of extant organisms involves a very great
deal of both ecology and cladistics.  This equates more or less to the
study of spatial factors in evolutionary ecology, which is a pretty big
field.  I don't think there's such a vacuum here.  It's unfortunate that
we're so ignorant about the phylogenies of most organisms.  But that
hasn't made us geniuses about their ecologies either.'

No, not a vacuum, but a fairly big divide between the interesting (and
sometimes surprising) results from phylogeography, and the efforts of
cladists who first look at maps AFTER they've built their trees.

There used to be an analogous divide in conservation biology. Many papers
were written about 'populations' and their futures without regard to
population genetics and what it says about the effective sizes of real
'populations.' Population geneticists and conservation biologists sometimes
collaborated, but not often enough. Nowadays conservation genetics is a
field of its own, and intelligently informs conservation.

I appreciate that there's a scaling issue here. Most phylogeographic
studies deal with the twigs at the ends of fine branches in the Tree of
Life: relatively short distances and relatively short times. Some major
cladistic programs, on the other hand, are on a stupendous scale, like the
work on basal arthropod phylogeny which looks into time so deep that all
spatial factors can be lumped together as 'Earth'.

I'm looking forward, though, to seeing more geography in 'intermediate
scale' cladistics. Maybe we'll see contemporary locations tested as input
characters in cladistic analysis, or independently derived geological
results used to tweak the likelihoods of alternative trees. I wouldn't be
surprised if the big advances in the use of spatial information in
phylogenetics come from people with very little background in biogeography.
They could arrive at the conceptual gap between 'place' and 'historical
relationship' without knowing all that much about the past 40 years of
angry debate between the biogeographical factions.

They might even get very excited about reticulation, which after all is
solid evidence (barring the possibility of vector-transferred genes) that
two lineages were in the same place at the same time.

Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195

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