[Taxacom] Renner (2004) and words that dare not speak their names

[Michael Heads]

Hi Tim,

Just one more thing. As discussed, fossil-calibrated, molecular clock dates
for clades can only ever be minimums. However, in the Bayesian analyses
published by leading authorities, the minimum dates are ‘converted’ into
absolute clade ages by a cunning trick.

How much older than its oldest fossil can a clade be? This is unknown
(unless you look beyond the fossil record itself, e.g. at biogeography and
geology). However, in Bayesian analyses this value is *stipulated* – not
calculated – as a ‘prior’. It is essentially subjective and arbitrary. If
you want a younger age for your clades, you set a smaller prior, i.e. you
impose on the analysis the condition that a clade can be only a little
older than its oldest fossil, say 1 or 2 million years. In this way it is
easy to ‘calculate’ young clade ages (with statistical error bars!) that
falsify vicariance and support chance dispersal. (For more details and
examples, see: Heads, M. 2012. Bayesian transmogrification of clade
divergence dates: a critique. *Journal of Biogeography* 39: 1749-1756).

Why would intelligent people support such nonsense? As Goethe said, ‘… I
saw that most men only care for science so far as they get a living by it,
and that they worship even error when it affords them a subsistence’.
(In ‘*Conversations
with Goethe*’ by Peter Eckermann).

Michael

On Fri, Oct 18, 2019 at 7:57 AM Timothy Dickinson via Taxacom <
taxacom at mailman.nhm.ku.edu> wrote:

> data are data, and someone can analyze these occurrences again and we'll
> see what we see. what i find odd about this paper (Renner 2004), and its
> publication in IJPS, is that an alternative hypothesis does not seem to
> have been mentioned. in fact, "hypothesis" and "vicariance" appear only
> once each, in the titles of papers cited by the author. what were the
> reviewers, and the editor, thinking???
>
> well,to answer my own question, this paper comes from one of the IJPS
> special supplements, one on "Tropical Intercontinental Disjunctions."
> the lead paper by Givnish and Renner does explore the competing claims
> of dispersal and vicariance, as do some of the other papers. Renner's
> paper appears to be a data-only contribution setting the stage (from a
> particular POV to be sure) for the discussion of amphiatlantic
> disjunctions. the editors for this special issue (Givnish and Renner?)
> give the last word to Robert Thorne ("It is most gratifying to this
> biogeographer to see in the contributions to this volume that the
> zealotry of the recent vicariance biogeographers has returned to
> normalcy with the current acceptance of vicariance, long�distance
> dispersal, and immigration from the boreotropics as possible
> explanations of intercontinental disjunctions."), so ok, the overall
> perspective seems to be one of vindicating dispersal while accepting
> vicariance.
>
> i think it's unfair to dismiss out of context this one paper (by
> Renner). the other papers in this issue suggest to me that the editors
> and authors *are* thinking about the constraints on the possible
> explanations for the disjunctions they describe.
>
> ---tad.
>
>
>
> <++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> <Tim Dickinson
> <Senior Curator Emeritus
> <ROM Green Plant Herbarium (TRT)
> <
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-- 
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—80520271968


*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>