[Taxacom] Transatlantic rafting not uncommon
Herbert Jacobson
jakejudy at hotmail.com
Fri Oct 21 12:51:00 CDT 2011
2011
Michael's response reminded me of a line from one of Robert Parker's Spencer mysteries. Spencer observes two events that appear linked. He rejects coincidence (or chance events) as an explanation. A character in the story asks him if he believes in coincidence and Spencer replies, I do but it doesn't do us any good.
Rafting also reminds of all the island chains that where hypothesized as dispersal routes before the acceptance of plate tectonics.
Herb
> Date: Thu, 20 Oct 2011 19:48:16 -0700
> From: michael.heads at yahoo.com
> To: kennethkinman at webtv.net
> CC: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Transatlantic rafting not uncommon
>
> Hi Ken,
>
> The more detailed study by Vidal et al. (2008) does indeed provide additional evidence for vicariance that Macey et al. (2004) were unaware of, as it shows that the two trans-Atlantic clades are themselves mutually allopatric. One is in western Mexico, western Cuba, Spain/Morocco and Turkey, the other is in South America, Greater Antilles and subsaharan Africa. The two overlap only in western Cuba. The overlap can be attributed to dispersal (range expansion), but no other dispersal is needed. Why is there such neat allopatry between the two trans-Atlantic clades? And why did each clade only disperse once across the Atlantic? This distinctive combination of the two phenomena would be simply explained by vicariance and there is no need to invoke chance events.
>
> Michael
>
> Wellington, New Zealand.
>
>
> My papers on biogeography are at: http://tiny.cc/RiUE0
>
>
> ________________________________
> From: Kenneth Kinman <kennethkinman at webtv.net>
> To: taxacom at mailman.nhm.ku.edu
> Sent: Friday, 21 October 2011 2:56 PM
> Subject: Re: [Taxacom] Transatlantic rafting not uncommon
>
> Dear All,
> I guess this thread is getting nowhere. Be careful what you ask
> for. I asked for a shred of evidence, and I am referred to one small
> shred in an older paper (Macey et al., 2004) based on a very limited
> sample of species and only on mitochondrial sequences. Doesn't seem to
> matter that Vidal et al (2007) and Muller et al. (2011) considerably
> expanded the number of species sampled and more gene sequences----they
> dared to challenge the primacy of vicariance, and that is apparently a
> no-no in panbiogeography circles.
> So I guess panbiogeographers (at least the ones that I am familar
>
> with) prefer old data in older papers, as long as they have "nice maps"
> and don't challenge some of their favored vicariance conclusions.
> Anyway, I certainly don't think that "repeated patterns are
> meaningless". However, I don't discriminate against dispersal patterns
> in favor of vicariance patterns. The truth is almost certainly going to
>
> be a mix of the two for many taxa (much to the discomfort of those who
> are heavily invested in vicariance patterns and seem to have a visceral
> reaction to dispersal patterns that might be challenging them).
> ---------Ken Kinman
> P.S. I am not holding my breath for any fossil Amphisbaenians at all in
>
> the uppermost Cretaceous, much less earlier (before South America and
> Africa separated). I just can't believe that Cretaceous amphisbaenians
> (if they existed at all) were less fossilizable or less discoverable
> than those throughout the Cenozoic. These are not the kind of animals I
>
> would expect to have undiscovered ghost lineages. Those who think such
> a ghost lineage exists in this case are probably indulging in wishful
> thinking. So in my view, I am siding with authorities with the widest
> sampling of taxa and data, and those citing "authorities" basing
> conclusions on less sampling and less data would do well to put up or
> shut up.
>
> -----------------------------------------------------------
> Michael Heads wrote:
> Hi Ken,
> Your evidence for amphisbaenians not being present in the
> Cretaceous is derived from (1) a literal reading of the fossil record
> (fossil age = clade age), and (2) the argument from authority (Vidal
> etc. are the acknowledged experts on the group, therefore they are
> right. Exposing fundamental flaws in these authors' logic
> is irrelevant 'nitpicking' because they 'actually study the group').
>
> Accepting a literal reading of the fossil record implies that
> biogeography is caused by random trans-oceanic dispersal and that any
> repeated patterns are meaningless. There is a vast amount of evidence
> for amphisbaenians and other groups being much older than indicated by
> their fossil record (and fossil-calibrated clocks), but you don't
> accept biogeographic evidence as it is all caused by chance. So
> why are more and more authors putting distribution maps in their
> abstracts at Molecular Phylogenetics and Evolution? Are all these
> simple, clear-cut distributions really just due to chance? If they are
> not, this suggests that a literal reading of the fossil record
> might be misleading. One interesting study of amphisbaenians (with
> very nice maps) concluded: 'Old and New World Amphisbaeniidae ... are
> monophyletic, so that this family dates back at least to the opening of
> the Atlantic Ocean 80 MYBP'. (Macey et al, Mol. Phylogen. Evol. 33:
> 22. 2004).
>
> Michael Heads
> Wellington, New Zealand.
> My papers on biogeography are at: http://tiny.cc/RiUE0
> ________________________________
> From: Kenneth Kinman <kennethkinman at webtv.net>
> To: taxacom at mailman.nhm.ku.edu
> Sent: Friday, 21 October 2011 4:44 AM
> Subject: Re: [Taxacom] Transatlantic rafting not uncommon
> Hi Michael,
> Well, the clades "could" perhaps be older than they
> estimated, but I doubt "much older" if you are suggesting that these
> families split
> up during the Cretaceous. Amphisbaenians have a pretty good fossil
> record in the Cenozoic, and only the most basal family goes back to the
> Middle Paleocene. So where is the fossil record of all these families
>
> in the Cretaceous? I doubt that they exist,
> because the living families
> increasingly appear to have split up during the early-to-mid
> Cenozoic.
> And I'm not talking just about Vidal's paper. Take a
> look at the recent paper published by Muller et al., 2011, in Nature,
> describing
> Cryptolacerta (an Eocene fossil which appears to be part of the sister
> group to Amphisbaenia). Their phylogeny and timeline (based on both
> morphological and molecular data) indicates that Amphisbaenia originated
> near the beginning of the Cenozoic, with the basal family Rhineuridae
> splitting off in the early Paleocene from the clade containing the other
> families.
> Sure, this basal split could have occurred in the
> uppermost Cretaceous, with Rhineuridae and the other clade both
> surviving the end-Cretaceous extinction. However, neither the fossil
> record nor molecular data supports your
> position that it happen even earlier than
> that (before Africa and South America separated). If you or John can
> offer a shred of evidence to counter the views of these specialists in
> amphisbaenian evolution, I would like to hear it. Nitpicking at their
>
> papers is easy, but let's here some solid evidence from you that
> Amphisbaenia even existed (much less diversified) before Africa and
> South America separated. Otherwise, I have to go with the evidence
> published by these various herpetologists who actually study this group,
> and whose conclusions generally make sense to me and are backed up by a
> variety of data.
> ------------Ken Kinman
>
>
>
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