[Taxacom] Panbiogeography

[Michael Heads]

Hi Jason,

You say you'd have preferred a definition, but I don't find definitions as
interesting as facts and ideas. Anyone can make up a definition. So I gave
you some data.

Sample size: the authors could have studied the plants for 20 years and
found a seed that dispersed 2 m rather than 1 m, but this would
hardly affect the argument. You say they'd need seeds large enough that
they could track, but they did track them - this is how they found how far
they dispersed.

You say 'taking the 1m from the article and multiplying it to get "1,5
million times" is, at best, inaccurate'. I'd be happy to change the number
- so how much wider do you calculate the distribution gap (across the
Tasman) is than the greatest dispersal distance in the plants?
You say that I 'accuse' Meudt and Bayly. All I said was: they 'concluded
that the mechanisms of the process in the two species are 'unknown' and
'hard to envisage''. That's not an accusation, and I think their point is
nicely made.

You wrote: 'you are perfectly happy (in general I mean, not
discussing the specifics Veronica sp) with accepting the existence of as
yet unknown tectonic events that can explain all biogeographical events'.
I've never said anything like that!  For example, if you read what I've
written, you'll see that I attribute great significance to major climatic
events and associated sea level changes.

Michael


On Tue, Apr 1, 2014 at 11:11 AM, JF Mate <aphodiinaemate at gmail.com> wrote:

> Thanks Michael for your response. I would have rather had a definition than
> a particular example picked a propos but I guess it will have to do.
> Notwithstanding my lack of training as a botanist or knowledge in the genus
> Veronica,  I have two problems about your explanation.
>
> Firstly the specifics of your example. The distance travelled by a sample
> of between 193 and 36 seeds (check it out, fig 3) when splashed by rain is
> hardly enough when discussing dispersal. It is useful when studying the
> general ecology of a species or, as was the intention of the authors, on
> the biomechanics of hygrochastic capsule dehiscence, but that?s it. You
> either need seeds large enough that you can track or else studies of
> population genetics. But taking the 1m from the article and multiplying it
> to get "1,5 million times" is, at best, inaccurate.
>
> As a more general argument, I find fault with your logic. You accuse Meudt
> and Bayly (2008, and by extension I suppose non-panbiogeographers) of not
> calculating the actual probability of long distance dispersal in each
> individual case, yet you are perfectly happy (in general I mean, not
> discussing the specifics Veronica sp) with accepting the existence of as
> yet unknown tectonic events that can explain all biogeographical events.
> Don't you think this is a bit unfair?
>
> As a final comment, there are many examples of events where the probability
> cannot be calculated. This doesn't mean that they are a throwback to a
> pre-scientific time, as you have subtly insinuated.
>
> Best
>
> Jason
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-- 
Dunedin, New Zealand.

My recent books:

*Molecular panbiogeography of the tropics.* 2012. University of California
Press, Berkeley. www.ucpress.edu/book.php?isbn—80520271968

*Biogeography of Australasia:  A molecular analysis*. 2014. Cambridge
University Press, Cambridge. www.cambridge.org/9781107041028