Taxacom: supposed evidence of Pacific ignuana dispersal

Sat Mar 22 17:22:35 CDT 2025

How do observations on dispersal in *individuals* relate to *clade
*distribution?
Every *individual* has dispersed to its present location, and so it is
imagined that a *clade* must develop its range in the same way. (Mayr
argued that every clade except very local endemics starts at a point and
attains its distribution by moving out from there).  But clades - unlike
individuals - can develop their distribution in situ, by vicariance and
without any dispersal, e.g. northern hemisphere Cupressaceae diverging from
southern hemisphere Cupressaceae.

  The break between iguanids in Fiji and their sister group, agamids, in
PNG - Eastern Australia is also seen in many other family-level groups,
e.g. the plant family Degeneriaceae of Fiji, sister to Himantandraceae of
PNG-eastern Australia.

On Sun, Mar 23, 2025 at 4:18?AM Kenneth Kinman via Taxacom <
taxacom at lists.ku.edu> wrote:

> Hi Geoff,
>         I agree.  This is a fine research paper.  And if iguanas can
> travel 300 km. overseas in recent times, much further voyages over millions
> of years are very probable.
>         And of all the iguanas to break a dispersal record, it is the
> desert iguana.  On land, they can survive very long periods of dehydration
> and lack of food, so doing so on a floating island of vegetation makes them
> the best suited for such a voyage.   A large island of many trees would be
> even more ideal with a source of food making survival even more likely.
>                               ------------Ken Kinman
> ________________________________
> From: Taxacom <taxacom-bounces at lists.ku.edu> on behalf of Geoff Read via
> Taxacom <taxacom at lists.ku.edu>
> Sent: Friday, March 21, 2025 6:25 PM
> To: taxacom <taxacom at mailman.nhm.ku.edu>
> Subject: Re: Taxacom: supposed evidence of Pacific ignuana dispersal
>
>
>
> Here's one of the news articles mentioned by John.
>
>
> https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fapnews.com%2Farticle%2Figuana-fiji-raft-float-journey-travel-9732d828c28a8374a6873fbc1b3d4af2&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141442130%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=6WKsAPwM%2BvUEscb0Di0iLffEk2qc1TFF4%2FzdoXLABlc%3D&reserved=0
>
> I've read the PNAS article and it does seem to be a very thorough
> even-handed assessment of all the possibilities in their discussion.
>
> They say humans have observed iguanas making landfall on islands and quote
> this presumably famous instance:
>
> "In 1995, a vegetation mat
> with at least 15 individual green iguanas (Iguana iguana) that likely
> originated on the islands of Guadeloupe was observed making landfall
> on Anguilla, an island 300 km away that was already inhabited by
> a different species of iguana, I. delicatissima"
>
> One quibble is that they work at a genus-level with little mention of
> species.  The genus is an 'it' as though it is a physical entity. A
> practice more familiar of palaeontologists rather than molecular biologists.
>
> This quote illustrates the style:  "Brachylophus , which contains 4 extant
> and 1 extinct species, is morphologically divergent from other iguanas and
> occurs extremely far from all of its extant relatives"
>
> Substitute 'are' for 'is' and 'their' for 'its' and see how it reads. The
> actual species is Brachylophus bulabula.  It gets just one mention (in a
> figure), and there are relations on different Fijian islands, plus
> apparently also one iguana human-transported.
>
> --
> Geoffrey B. Read, Ph.D.
> Wellington, NEW ZEALAND
> gread at actrix.gen.nz
>
>
>
> >---- Original Message ----
> >From: John Grehan via Taxacom <taxacom at lists.ku.edu>
> >To: "taxacom" <taxacom at mailman.nhm.ku.edu>
> >Sent: Fri, Mar 21, 2025, 9:33 AM
> >Subject: Taxacom: supposed evidence of Pacific ignuana dispersal
> >
> >Some of you may have seen this as it's been splashed around widely on the
> >propaganda circuit.
> >
> >Iguanas rafted more than 8,000 km from North America to Fiji PNAS 2025
> Vol.
> >122 No. 12 e2318622122 https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdoi.org%2F10.1073%2Fpnas.2318622122&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141459535%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=6LDg9cRBQaoKYJemEAUUZAOEdHG%2BQpozc%2BRo3h0TQ1Q%3D&reserved=0
> >
> >It's just another duplication of the same old trash. Abstract claims that
> >?Here, we investigate the occurrence and timing of the greatest known
> >long-distance oceanic dispersal event in the history of terrestrial
> >vertebrates?the rafting of iguanas from North America to Fiji.? Trouble
> >with this is that it makes out that this ?long-distance oceanic dispersal
> >event? is an established scientific fact when it is not.
> >
> >
> >Then they assert that ?Iguanas are large-bodied herbivores that are
> >well-known overwater dispersers, including species that colonized the
> >Caribbean and the Gal?pagos islands.? when there is absolutely no
> >empirically based evidence that the Galapagos iguanas ever dispersed
> >overwater to the Galapagos.
> >
> >
> >
> >And the central rot (as in decay) of their claims is the same as all the
> >other center of origin-chance dispersal recipes: The divergence estimate
> is
> >based on fossil calibration which can only render minimum ages. Anything
> >else (such as priors) is conjecture. So their timeline is erroneous in
> this
> >respect. The other is that their ancestral-areas analysis is simply a
> >recipe that cannot empirically distinguish between chance dispersal and
> >vicariance as either can generate the same phylogenetic area sequence.
> >
> >
> >
> >Given their calling attention to the Galapagos it seems an incredible
> >oversight to have missed Heads & Grehan 2021 on Galapagos biogeography,
> >including the Fiji connection. I've seen this before, where there is a
> >narrow range of citations restricted to the same school of thought.
> >Anything else does not exist. This, then, is the pinnacle of academic
> >achievement in the US (maybe a good argument for the government trashing
> >science?).
> >
> >
> >Cheers, John
>
>
> _______________________________________________
> Taxacom Mailing List
>
> Nurturing nuance while assailing ambiguity for 38 years, 1987-2025.
>
> Send Taxacom mailing list submissions to: taxacom at lists.ku.edu
> For list information; to subscribe or unsubscribe, visit:
> https://lists.ku.edu/listinfo/taxacom
> You can reach the person managing the list at: taxacom-owner at lists.ku.edu
>
>
> _______________________________________________
> Taxacom Mailing List
>
> Nurturing nuance while assailing ambiguity for 38 years, 1987-2025.
>
> Send Taxacom mailing list submissions to: taxacom at lists.ku.edu
> For list information; to subscribe or unsubscribe, visit:
> https://lists.ku.edu/listinfo/taxacom
> You can reach the person managing the list at: taxacom-owner at lists.ku.edu
>
>
>

-- 
Dunedin, New Zealand.

My books:

*Biogeography and evolution in New Zealand. *Taylor and Francis/CRC, Boca
Raton FL. 2017.
https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.routledge.com%2FBiogeography-and-Evolution-in-New-Zealand%2FHeads%2Fp%2Fbook%2F9781498751872&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141473550%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata¦hYMQe32srj52yQdG2aj07DZzvPSMWIe0FZLQdymjU%3D&reserved=0

*Biogeography of Australasia:  A molecular analysis*. Cambridge University
Press, Cambridge. 2014. https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.cambridge.org%2F9781107041028&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141488443%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=WM4NyGl%2FSqFJrdwoFCV5pmIxT1WgzFKcwBSyUJiE3fg%3D&reserved=0

*Molecular panbiogeography of the tropics. *University of California Press,
Berkeley. 2012. https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ucpress.edu%2Fbook.php%3Fisbn%3D9780520271968&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141500704%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=RJ8UCYcZHG7NdPpe0fq6Fwpp4W1EZrMOLLCMLFAZ7ns%3D&reserved=0

*Panbiogeography: Tracking the history of life*. Oxford University Press,
New York. 1999. (With R. Craw and J. Grehan).
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fbooks.google.co.nz%2Fbooks%3Fid%3DBm0_QQ3Z6GUC&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141512720%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=quVseQHJYLNZcXUTdTTc2vpkBMsLYgp4mq%2FLK%2B7Jd2I%3D&reserved=0
<https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fbooks.google.co.nz%2Fbooks%3Fid%3DBm0_QQ3Z6GUC%26dq%3Dpanbiogeography%26source%3Dgbs_navlinks_s&data%7C02%7Ctaxacom%40lists.ku.edu%7Cb10d0161df28494fb6f208dd699013b2%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782790141524880%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=vNLKW9raQFmy5sL4I4NSOAzHTAAsYMGA%2FTDu7JRnX1c%3D&reserved=0>