[Taxacom] Panbiogeography

[JF Mate]

Dear Michael and John,

sorry if you received a half-baked draft. I let my son play with the
phone and he did what kids do. So if it left you scratching your head,
now you know why.

"You've misunderstood my position - my work is based on the law of
large numbers. I'm not interested in one-off phenomena,
but in patterns that are repeated many times.
You seemed to think that the 'everything is everywhere' topic was not
a major issue, that's why I looked up the large
number of recent papers that deal with it."

I don´t understand your answer in the context of, say, <1mm organisms.
If widespread dispersal is a double digit phenomenon, isn´t this
relevant to consider? As Pierre said, if Panbiogeography accepted
dispersal as most people understand it, they would just be a flavour
of vicariance biogeography. As for "everything is everywhere". If you
can produce a paper that supports this from 1950-1970 I will concede
that this was the accepted dogma.


"Why do you keep saying that I reject dispersal when I've already told
you that my books propose large numbers of examples?
I use dispersal - rather than sympatric speciation - to explain
overlap, and because so many groups overlap,
I regard dispersal as very important." ... (John) "Just saying so does
not make it true. I think this is a bit naughty."

There is nothing naughty in asking for testable definitions. Your
definition of dispersal (as I understand it) is fundamentally
at odds with experimental evidence. When pressed you mention the
movement of plants from one corner of the garden to the other
or by alpine plants which disperse a meter here or there. This is why I take
issue with this definition that you and John spouse. You don´t reject
it outright, but you seek to trivialize it by pointing at examples
that support this idea. Anybody can cherry pick in this way. It is
like saying that dispersal can be all the way to the moon
simply because Deinococcus radiodurans hitched a ride on a satellite.
Or humans for that matter. There are numerous examples
of long range dipersal that happen frequently. There are also taxa
which cannot cross a road or a river or a forest clearing. Dispersal
is a range that is much greater than you want to consider.

"For many dispersalist approaches the explanatory power generates
acknowledged mysteries, puzzles, anomalies etc.
This is greater explanatory power? "

I call it reality, but to each their own.

"On the Lord Howe island palms, you say "see reply to Tuessy (2006) by
Savolainen et al (2006) which answers your concerns".
Stuessy's points are important and the reply by Savolainen et al. is
very weak. It depends entirely on their clock date for
the 'sympatric' speciation event, and this was calibrated by assuming
that Mascarenes endemics could be no older than their
island! (See my critique of this naive approach in Syst Biol 60: 204. 2011)."

Amongst the points mentioned by Savolainen et al, they pointed out
that island lacked the structural
complexity to account for physical barriers of any sort. Allopatry
also requires a smoking gun you see, like vicariance it cannot be
assumed.
If you can provide actual evidence of a barrier that could have
divided the ancestral island population then you have a case.
Otherwise
sympatry can be assumed, at least for now.

"You say Peccoud et al. "are not making any phylogeographic claims".
They map localities (geography) onto a phylogeny
and use that to make deductions about 'sympatric speciation' (one of
their keywords). That's phylogeography. "

If they used samples from another locality they have to indicate so in
the phylogram. That is just proper way to go about it.
The indication on sympatric evolution comes not just from the evidence
of a range of hybridisation rates discovered in the paper
and the monophyly of the host races, but from the the lack of mtDNA
variability which indicates very recent origin for the lineages and
no allopatric mechanism to account for it.

"Or they are old races that have not differentiated much."

You would have to provide a mechanism that can stop random genetic
mutations from accumulating in both the aphid lineages and the
symbiotic
microorganisms. Wishing for this is not enough.

Jason