Taxacom: supposed evidence of Pacific ignuana dispersal

[Kenneth Kinman]

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%7C36a8f68676294fd3afdc08dd6954c11c%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782534932890633%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=v3EN%2BuxQhCi2wDVpQAscC6M4s5FfW5P0a1yLqoZ%2FrwY%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%7C36a8f68676294fd3afdc08dd6954c11c%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638782534932910267%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=wdJcKMN6c0cXzS7ZlnGc50fSSo2dCJqd1QGL16YRQfs%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


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