[Taxacom] Panbiogeography

[JF Mate]

Dear Michael:

"Another colleague sent a good paper on the 'everything is everywhere'
debate - it's:
O'Malley, M. A. (2007). The nineteenth century roots of'everything is
everywhere'. Nature Reviews Microbiology, 5(8), 647-651. 'The
identification of geographical patterns in microbial distributions has
begun to challenge purely ecological explanations of biogeography and
the underlying principle of 'everything is everywhere: but the
environment selects'.' It's a good review."

I don?t have access to this paper so I cannot add anything to this.
Nevertheless, what are you using to substantiate your next comment?:
 "Of course, no-one is suggesting that dispersal does not occur, but
chance dispersal/ecology does not seem to be the explanation for these
patterns."
What is chance ecology? Which patterns do you refer to? Pantaneto and
colleagues are careful to note that, although certain lineages in
their phyla show the effects of vicariance, a large proportion of
their taxa are indeed widely dispersed (they use the term themselves).
So how does this negate dispersal? Again, nobody denies vicariance, or
that it may be more important than dispersal in many situations or at
particular scales, but the evidence of dispersal is rife so unless
there is a testable hypothesis to distinguish your two dispersals, we
will be arguing forever and not make any progress,

As for sympatric speciation and range overlap, range overlap of the
hosts/habitats may or may not be fully concordant. So why would your
ridge species simply stay on that ridge? Why would adaptation to a
ridge not preadapt it to living on cliffs? We call it a ridge but for
your species it may be an inaccessible area due to dryness, exposure,
temperature oscillations, etc. Once the problem is solved, there are
other ridges to move into or other "ridge-like" environments that are
suddenly accessible. Once a new niche is broken into the range
limitations of the ancestral population/species will no longer fully
apply. In addition, consider that, it is likely that most of these
jumps will occur at the edges of a range, where a species? survival
chances are at their limit (high selective pressures); where gene-flow
may also be limited (distance to bulk of population gene-pool,
suitable habitat is more fragmented hindering migration); and where
the population may be small (drift more likely) the resulting
ditribution will show little overlap.

Best

Jason