[Taxacom] Tortoise self-rafting sea voyage

[John Grehan]

Peter et al,

 

No, I could not explain how I did not mean that because that was what I
was trying to say about how the observation was being interpreted. It
seemed that the observation of the tortoise arrival was seen by the
authors to be biogeographically significant because it confirmed an
assumption that they had already made - the assumption being that this
was how the tortoises arrived at their Indian Ocean island locations. If
one does not make the assumption, the floatation of the tortoise has no
necessary biogeographic meaning. And by "no necessary biogeographic
meaning" I am not saying that it has no biogeographic meaning at all.

 

John

 

________________________________

From: Hovenkamp, P. (Peter) [mailto:Hovenkamp at nhn.leidenuniv.nl] 
Sent: Wednesday, April 11, 2007 4:09 AM
To: John Grehan; g.read at niwa.co.nz; TAXACOM
Subject: RE: [Taxacom] Tortoise self-rafting sea voyage

 

To all empirical scientists on this list: 

 

I can't help drawing your attention to the apparent equivalence of these
two statements:

 

"Of course without the assumption the floatation is no more
biogeographically singificant than  (...)" 

 

and

 

"An observation is only biogeographically significant if it confirms an
assumption already made"

 

John, could you please explain how you did not mean this?

 

Peter Hovenkamp


 

________________________________

Van: taxacom-bounces at mailman.nhm.ku.edu namens John Grehan
Verzonden: di 10-4-2007 14:31
Aan: g.read at niwa.co.nz; TAXACOM
Onderwerp: Re: [Taxacom] Tortoise self-rafting sea voyage

I noticed the nice propaganda statement in the link as follows:

"trans-oceanic dispersal is assumed to be the mechanism by which
tortoises and many other animals became established on islands
throughout the world"

It's propadanda because it implies that everyone makes this assumption.
Of course without the assumption the floatation is no more
biogeographically singificant than the thousands of bugs that fly to New
Zealand every year.

This all comes down to the dichotomy between the belief that individual
cases of mobility are the test of biogeography, or whether spatial
analysis is the test of the biogeographic signficance of individual
mobility.

John Grehan


> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Geoff Read
> Sent: Tuesday, April 03, 2007 5:25 PM
> To: TAXACOM
> Subject: [Taxacom] Tortoise self-rafting sea voyage
>
> Interesting report on a large tortoise which walked out of the sea on
a
> Tanzania beach, reckoned to have drifted from Aldabra atoll (740km).
It
> had a lovely crop of barnacles.
>
> Gerlach, J., Muir, C. & Richmond, M.D. (2006) The first substantiated
> case of trans-oceanic tortoise dispersal. Journal of Natural History,
> 40, 2403 - 2408.
>
>
http://www.informaworld.com/openurl?genre=article&title=Journal%20of%20N
at
>
ural%20History&issn=0022%2d2933&volume=40&issue=41&spage=2403&epage=2408
&d
>
oi=10%2e1080%2f00222930601058290&date=2006&atitle=The%20first%20substant
ia
>
ted%20case%20of%20trans%2doceanic%20tortoise%20dispersal&aulast=Gerlach&
au
> first=Justin&auinit=D%2e&sid=informa%3ainformaworld
>
>
> Geoff
> --
>    Geoff Read <g.read at niwa.co.nz>
>     http://www.annelida.net/
>     http://www.niwascience.co.nz/ncabb/
>
>
>
> _______________________________________________
> Taxacom mailing list
> Taxacom at mailman.nhm.ku.edu
> http://mailman.nhm.ku.edu/mailman/listinfo/taxacom

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