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[Taxacom] Dispersal paradigm (was: Antarctic dispersal)

JF Mate aphodiinaemate at gmail.com
Wed Jun 11 16:52:46 CDT 2014 

John,


Statements such as ?This is the philosophy that if something is
correct it will be supported by the majority. History shows that this
is not always the case.? and ?Not so imaginary. [other side] indicate
that you feel like you are battling something or someone. Further, you
label this opponent ?dispersalism? (a label that suggests that they
somehow reject vicariance) and paint them with an interesting choice
of adjectives (mystery, allure, etc). If your arguments are solid the
adjectives are superfluous. In any case, when I say that the majority
of biologists would agree that vicariance is likely to be the most
common, why are they wrong? Because they are not saying that
vicariance is the only mechanism?


Anyway, you contend that ?... the point here is that the
misrepresentation of minimal ages as actual or maximal has led to
erroneous results.? I am sure that you are aware that phylogeny
calibration allows for priors to be used and that this is common
practice to use log priors to accommodate not just for the uncertainty
in the stratigraphy of fossils but also for origination uncertainty.
So is your complaint against someone in particular who used a very
tight prior or about calibrations in general?

Finally, reliance solely on patterns is methodologically flawed
without a timing reference point (the one you ditched). You could, for
example, argue that the prevailing winds, currents or disperser
migrations aided the movement of some taxa resulting in a pattern that
is accidentally congruent with vicariance. Without the time frame it
would all look the same.

There are uncertainties inherent in the use of fossils or any other
calibration reference but it seems preferable (and more logical) than
suggesting that a commonly observed phenomenon (organisms moving
about) has absolutely no effect on biogeographical patterns at the
macro scale.

Best

Jason

On 10 June 2014 22:32, John Grehan <calabar.john at gmail.com> wrote:
> Jason,
>
> Comments inserted below:
>
>
> John, repeating Ken?s name is not going to make the duality of
> biogeographical processes go away.
>
>
> It was Ken?s views that I was responding to so mentioning his name seemed to
> make sense.
>
>
> Ken has devoted more time and effort to try and discuss this with you than
> it is worth it because, lets face it, he is keen to discuss it and you are
> not.
>
>
> Huh?
>
>
> So by attrition you may silence him but it will be a pyrrhic victory.
>
> What attrition?
>
>
> In any case, in layman?s terms your arguments essentially are:
>
> -Stuff disperses but not so much that it can ever compete with
> vicariance. Keep it vague so it is inherentely untestable too.
>
>
> Do not understand this as being my argument. Please give specifics.
>
>
>
> -Fossils are minimum age points but I can go back as far as it is
> needed to prove that, eventually, a tectonic event is there to explain
> the distribution.
>
>
> It?s not a matter of going back as far as needed. It is a matter of
> identifying a tectonic feature that is in the present.
>
>
>
> -Gene evolutionary rates are completely, utterly, totally random and
> essentially impossible to calibrate accurately.
>
>
> That is one possibility, but it has not been the focus of discussion.
> Rather, it is the problematic nature of calibrations being minimal rather
> than actual.
>
>
> This is important because the key difference between dispersal and
> vicariance is timing.
> If you eliminate the chance for timing you cannot disprove vicariance.
> Ergo panbiogeography wins.
>
>
> Not sure how to make sense of this characterization.
>
>
>
> -And always use catchy adjectives to label the ?other? side and appeal
> to conspiracies to lend further credence to your cause.
>
>
> Which conspiracies? Please specify (not suggesting you are necessarily
> wrong, but I do not know which conspiracies to which you refer unless you
> state them).
>
>
>
> I find all this sad to be perfectly honest. If your argument was that
> vicariance is more important than dispersal you would have broad,
> almost universal agreement.
>
>
> This is the philosophy that if something is correct it will be supported by
> the majority. History shows that this is not always the case.
>
>
> As a simple numbers game it is immediately
> obvious that if you split a continent in half you do the same to the
> distributions of all the organisms.
>
>
> True ? but the point here is that the misrepresentation of minimal ages as
> actual or maximal has led to erroneous results.
>
>
> But it is your insistence to paint
> the "other" (imaginary) side with colourful objectives that just makes
> it damn annoying.
>
> Not so imaginary. Sorry you do not like my (unspecified [I think you mean
> adjectives]), but it?s impossible to keep everyone happy all of the time.
>
>
> John Grehan
>
>
>
> On Tue, Jun 10, 2014 at 4:04 PM, JF Mate <aphodiinaemate at gmail.com> wrote:
>>
>> John, repeating Ken?s name is not going to make the duality of
>> biogeographical processes go away. Ken has devoted more time and
>> effort to try and discuss this with you than it is worth it because,
>> lets face it, he is keen to discuss it and you are not. So by
>> attrition you may silence him but it will be a pyrrhic victory. In any
>> case, in layman?s terms your arguments essentially are:
>>
>> -Stuff disperses but not so much that it can ever compete with
>> vicariance. Keep it vague so it is inherentely untestable too.
>>
>> -Fossils are minimum age points but I can go back as far as it is
>> needed to prove that, eventually, a tectonic event is there to explain
>> the distribution.
>>
>> -Gene evolutionary rates are completely, utterly, totally random and
>> essentially impossible to calibrate accurately. This is important
>> because the key difference between dispersal and vicariance is timing.
>> If you eliminate the chance for timing you cannot disprove vicariance.
>> Ergo panbiogeography wins.
>>
>> -And always use catchy adjectives to label the ?other? side and appeal
>> to conspiracies to lend further credence to your cause.
>>
>> I find all this sad to be perfectly honest. If your argument was that
>> vicariance is more important than dispersal you would have broad,
>> almost universal agreement. As a simple numbers game it is immediately
>> obvious that if you split a continent in half you do the same to the
>> distributions of all the organisms. But it is your insistence to paint
>> the "other" (imaginary) side with colourful objectives that just makes
>> it damn annoying.
>>
>> Best
>>
>> Jason
>>
>> On 10 June 2014 18:13, John Grehan <calabar.john at gmail.com> wrote:
>> > I think Ken is quite right to attribute the allure of dispersal
>> > explanations for evolution as a product of personal experience.
>> > Dispersal
>> > as an ecological phenomenon (the movement of animals and plants (seeds
>> > etc)
>> > is a highly visible phenomenon so it is not suprising that it has such a
>> > hold over explanations for vicariant (allopatric) differentiation. And
>> > certainly any species may spread to occupy a much larger areas, but this
>> > has to do with range expansion (or contraction), not differentiation.
>> > Obviously a widespread ancestor established its range in the first place
>> > through means of survival becoming means of dispersal.
>> >
>> >
>> > Ken may feel that ?the most vocal proponents of vicariance (since the
>> > acceptance of continental drift) have often overdone their backlash
>> > against
>> > the predominant dispersal paradigm? has not given any empirical
>> > foundation
>> > for such a view. This is not about a pendulum of popularity of an idea,
>> > but
>> > whether the idea (method, model, theory etc) works for the facts at
>> > hand.
>> > Dispersal models have to ignore or explain way allopatry, vicariance
>> > does
>> > not. Science is not about ?balanced? views for such a concept is purely
>> > political, not scientific. Einstein?s theory of relativity may have been
>> > an
>> > entirely ?unbalanced?, but it matters not a wit.
>> >
>> >
>> > It is not so much about disagreeing with Ken over panbiogeographic
>> > approaches that is of interest, but the nature of that disagreement.
>> > Ken?s
>> > view is based on assumptions about what is correct or not rather than on
>> > empirical evidence. Ken believes that fossil calibrated (or any
>> > historical
>> > calibration) of molecular divergence ages not minimal even though that
>> > goes
>> > against the facts. Panbiogeographic reconstructions are based on spatial
>> > analysis that recognizes the existence of allopatry being widespread
>> > among
>> > taxa, and that this allopatry can be correlated with tectonics that
>> > provides a hypothesis of an actual biogeographic age of origin. Some
>> > analyses show correlations with pre-drift tectonic formations, thus
>> > providing evidence of differentiation prior to drift taking place in
>> > particular regions.
>> >
>> >
>> >
>> > John Grehan
>> >
>> >
>> > On Mon, Jun 9, 2014 at 8:44 PM, Ken Kinman <kinman at hotmail.com> wrote:
>> >
>> >>
>> >>
>> >>
>> >> Hi Michael,                                                           I
>> >> suppose the centre of origin/dispersal view has been dominant for
>> >> thousands
>> >> of years because humans have been able to recognize that their own
>> >> species
>> >> is so prone to such dispersal.  And today biologists can see the
>> >> evidence
>> >> that our species (and related species like Homo erectus) dispersed from
>> >> smaller areas to occupy much larger areas (eventually including the
>> >> Americas for Homo sapiens).  How widely we should extrapolate that to
>> >> other
>> >> taxa is obviously debatable, but I still believe that the most vocal
>> >> proponents of vicariance (since the acceptance of continental drift)
>> >> have
>> >> often overdone their backlash against the predominant dispersal
>> >> paradigm.
>> >>       It really does far more harm than good to swing any pendulum too
>> >> far, and more recently we have the resulting opposing backlash of
>> >> dispersalists against too much vicariance.  Of course, this is not as
>> >> extreme as the pendulum swing which resulted in a total rejection of
>> >> all
>> >> paraphyletic taxa (and throwing all the babies out with the bathwater),
>> >> but
>> >> it is still problematic.  In both cases, I believe a middle ground will
>> >> be
>> >> found that results in more balanced approaches.  In my view that means
>> >> pulling back a bit on the vicariance front that went too far (and
>> >> easing up
>> >> on attacks against dispersalists), as well as accepting formal
>> >> paraphyletic
>> >> taxa where they are most useful (thus ending a decades-long backlash
>> >> against all paraphyletic taxa whether they were good or bad).   In any
>> >> case, I disagree with your panbiogeographic approach to both ratites
>> >> and
>> >> Order Crossosomatales, so I guess it is best to just agree to disagree
>> >> on
>> >> how much dispersal occurred during their evolution.  I also disagree
>> >> that
>> >> the age of the eudicot clade is nearly as problematic as you make it
>> >> out to
>> >> be.   So it goes.
>> >> ---------------------------Ken
>> >>
>> >> Michael wrote:
>> >> Whether or not ideas are accepted or popular is interesting for
>> >> sociology,
>> >> but is not relevant to logical, scientific argument. The centre of
>> >> origin/dispersal view is the dominant paradigm, and has been for
>> >> thousands
>> >> of years, but that does not mean it's right. In any case, the eudicot
>> >> age
>> >> is problematic (there is a whole section on it in my 2014 book (p. 67).
>> >>
>> >>
>> >> ----------------------------------------------------------------------------------------------------------------------------------------------------
>> >>
>> >>
>> >>
>> >>
>> >> _______________________________________________
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>> >>
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>> >>
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>> > http://taxacom.markmail.org
>> >
>> > Celebrating 27 years of Taxacom in 2014.
>>
>> _______________________________________________
>> Taxacom Mailing List
>> Taxacom at mailman.nhm.ku.edu
>> http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
>> The Taxacom Archive back to 1992 may be searched at:
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>>
>> Celebrating 27 years of Taxacom in 2014.
>
>

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