[Taxacom] New Caledonia as a classic lesson in dispersal

[Michael Heads]

Hi Ken,

The problem with the Nattier paper is that the approach they used, long
distance dispersal theory, didn't work; it did not
explain critical groups such as the New Caledonian endemic Amborella,
sister to all other angiosperms. Dispersal theorists
concluded that the group remains ‘puzzlingly enigmatic’ (Grandcolas et al.,
2008, p. 3312) and ‘paradoxically difficult to
interpret’ (Nattier et al., 2017, p. 6).

Michael

On Tue, Dec 11, 2018 at 3:09 AM Kenneth Kinman <kinman at hotmail.com> wrote:

> Dear All,
>          The paper by Nattier et al. (2017) is definitely worth reading.
> Here is a weblink to that article:
>
> https://www.nature.com/articles/s41598-017-02964-x
>
>
> ________________________________
> From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John
> Grehan <calabar.john at gmail.com>
> Sent: Sunday, December 9, 2018 11:45 PM
> To: taxacom
> Subject: [Taxacom] New Caledonia as a classic lesson in dispersal
>
> The New Caledonia paper raises quite a few issues of general relevance for
> biogeography. One of these concerns claims that 'short distance' dispersal
> involve a more complex and speculative combination of low probability
> compared with long distance dispersal. Ironically (there is quite a bit of
> irony in this paper) Heads points out that “‘short-distance’ dispersal is
> neither complex nor speculative, and is observed in almost all organisms
> using their normal means of dispersal (unlike the unique long distance
> dispersals used to explain allopatric speciation). He noted that Grandcolas
> (2017) and Nattier et al. (2017) both rejected normal, short-distance
> dispersal (and, presumably, the idea of metapopulations) around New
> Caledonia as ‘ad hoc scenarios’, but at the same time they explained the
> biogeography of New Caledonia by long-distance dispersal.
>
> Another critically important issue for biogeography is the concept of
> metapopulation persistence, Critical because it represents a process by
> which taxa persist despite landscapes emerging and submerging. It is the
> very quality of mobility by which organisms are able to persist in within a
> dynamic geology and topography (essentially Croizat’s concept of life as
> the uppermost geological layer). Heads points out that Nattier et al.’s
> (2017, p. 2) comparison of metapopulation theory with the ‘island-hopping
> scenarios’ for  Wallace (1881)  et al ignored the fact that the concept of
> island-hopping was unidirectional migration allowing very rare dispersal
> events across ocean basins (by non-standard means and with speciation)
> which is a very different process from metapopulation survival in situ,
> without speciation, and caused by regular dispersal by normal ecological
> means.
>
> Ironically (again) Nattier et al. (2017) accepted that the process might
> explain some New Caledonia groups with respect to six molecular clock
> studies proposing that New Caledonia clades and New Caledonia + Pacific
> islands clades that were older than 37 Ma (the supposed age of subaerial
> New Caledonia, the oldest island in the region). Nattier et al. took things
> both ways, either appealing to older lineages that long ago occurred
> somewhere else where they went extinct, but survived by hopping to New
> Caledonia - the details of which “remain to be established”. But then
> Nattier et al. (2017) also suggested that the six older groups ‘evolved by
> hopping/local dispersal mechanisms between terrestrial lands in the region”
> and have extinct members either on vanished islands or nearby continents.
> Heads points out that this view is actually consistent with metapopulation
> survival in the New Caledonia region, and with the idea that former islands
> (some still represented by seamounts) are critical in understanding
> contemporary biogeography. So this is a classic case where panbiogeographic
> models are condemned on the one hand and then used on the other. This is
> the kind of confusion that is often found in biogeographers who look to
> explain speciation by chance dispersal rather than understanding the role
> of ecological dispersal in the origin, establishment, and persistence of
> populations rather than as a mechanism for speciation.
>
> John Grehan
>
> <
> https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon
> >
> Virus-free.
> www.avast.com<http://www.avast.com>
> <
> https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link
> >
> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> _______________________________________________
> Taxacom Mailing List
> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org
> To subscribe or unsubscribe via the Web, visit:
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
> taxacom-owner at mailman.nhm.ku.edu
>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
> _______________________________________________
> Taxacom Mailing List
> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> The Taxacom Archive back to 1992 may be searched at:
> http://taxacom.markmail.org
> To subscribe or unsubscribe via the Web, visit:
> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
> You can reach the person managing the list at:
> taxacom-owner at mailman.nhm.ku.edu
>
> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>


-- 
Dunedin, New Zealand.

My books:

*Biogeography and evolution in New Zealand. *Taylor and Francis/CRC, Boca
Raton FL. 2017.
https://www.routledge.com/Biogeography-and-Evolution-in-New-Zealand/Heads/p/book/9781498751872


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


*Molecular panbiogeography of the tropics. *University of California Press,
Berkeley. 2012. www.ucpress.edu/book.php?isbn=9780520271968


*Panbiogeography: Tracking the history of life*. Oxford University Press,
New York. 1999. (With R. Craw and J. Grehan).
http://books.google.co.nz/books?id=Bm0_QQ3Z6GUC
<http://books.google.co.nz/books?id=Bm0_QQ3Z6GUC&dq=panbiogeography&source=gbs_navlinks_s>