[Taxacom] Selection pressure (Large dicynodont fossil)

John Grehan calabar.john at gmail.com
Wed Nov 28 07:08:55 CST 2018


Imagination is all well and good when grounded in some connected data. In
the case of imagined selection pressures there is no testable option that I
know of. Testing itself is always a potentially problematic quality
(falsification can be avoided by attributing incongruent results to either
poor data or to poor theory). And testing itself has to be appropriate.
There is that classic example of Darwin (or someone else) testing survival
of snails in seawater as if their survival demonstrated anything about
whether this was actually operable in the origin of trans-oceanic
distributions involving divergent taxa.

On Sat, Nov 24, 2018 at 2:13 PM Richard Zander <Richard.Zander at mobot.org>
wrote:

> Hah. Imagination is the groundwork of science. Then you test it. Theories
> derived from tested hypotheses, in the Bayesian sense, are predictions so
> well supported that you can bet on such being true with small chance of
> failure.
>
>
> -------
> Richard H. Zander
> Missouri Botanical Garden – 4344 Shaw Blvd. – St. Louis – Missouri – 63110
> – USA
> richard.zander at mobot.org Ofc: +1 314 577-0276
> Web sites: http://www.mobot.org/plantscience/bfna/bfnamenu.htm and
> http://www.mobot.org/plantscience/resbot/
>
> -----Original Message-----
> From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
> John Grehan
> Sent: Saturday, November 24, 2018 10:22 AM
> To: Ken Kinman
> Cc: taxacom
> Subject: Re: [Taxacom] Selection pressure (Large dicynodont fossil)
>
> Ken,
>
> My point was that it was all imaginary. Not science at all. Maybe there
> were such selection pressures, maybe there wasn't. It would be like saying
> that maybe dicynodonts got bigger because they wanted to. Before they got
> so big they obviously survived predation OK or would not have continued
> their lineage. Selection pressures can be demonstrated to exist within
> populations in the present as an empirical observation. Its another thing
> entirely to invoke its role for a historical change in the fossil record
> when there is not a shred of evidence either way. Its the stuff that makes
> evolution such bad science (or not science at all) and great fodder for
> anti-science folk (so far most of them don't realize how bad or they would
> have had a field day with this sort of stuff).
>
> John Grehan
>
> On Sat, Nov 24, 2018 at 10:39 AM Kenneth Kinman <kinman at hotmail.com>
> wrote:
>
> > John,
> >        Yet another "fairy tale" complaint?  I'm not sure if your
> > complaint is about the word "selection" or the word "pressure" or the
> > word combination.
> >         As for the large dicynodont, selection would not only have
> > protected them from their predators getting larger (survival selection).
> > It may have also been the result of bigger males having more offspring
> > (reproductive selection), either due to males fighting for females (or
> > possibly females choosing bigger males as mates).
> >         This positive selection for larger size worked very well
> > during the good times.  But when the end-Triassic extinction event
> > came along negative selection would have been particularly hard on the
> > larger animals.  Volcanism and the resulting climate change could have
> > easily resulted in starvation (and perhaps increased disease) in many
> taxa.
> >                               --------------Ken
> > ________________________________
> > From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John
> > Grehan <calabar.john at gmail.com>
> > Sent: Thursday, November 22, 2018 6:22 PM
> > To: taxacom
> > Subject: [Taxacom] Large dicynodont fossil
> >
> > So they found a large herbiroous dicynodont fossil that walked in an
> > upright manner, similar to large mammals like rhinos and hippos that
> > lived between 210 and 205.
> >
> > So to the question of why it was so large it was said " Researchers
> > believe selection pressures—potentially to protect themselves from
> > larger predators—may have been the driver behind their giant size"
> >
> > Good grief. Why is something so large? - selection pressure. Why is
> > something so small? - selection pressure. Why is something in between?
> > - selection pressure. Why do we have to rest science on such fairly
> > tales? - selection pressure. What would we do without selection
> > pressure? What would we do?
> >
> > John Grehan
> >
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