[Taxacom] Panbiogeography

[JF Mate]

"...that's normal, observed ecological dispersal. Long-distance
dispersal inferred from a phylogeny does not work like that - it can
happen anywhere, at any time. It is not correlated with any other
factor (wind, currents etc.) and in many lineages it is inferred to
occur only once in tens of millions of years..."
Michael, this dispersal you are talking about is the end product of
successful dispersal assuming the lineage survives to result in
speciation. It is a step beyond dispersal. So the question is, can you
accept the fact that stuff moves and that this ability to move, a
meter or a thousand kilometers, is essentially the same even if the
probability of the latter to be successful is much, much smaller than
the former?

"The new, revolutionary idea of chance as a calculated probability
began with Pascal and Fermat in the 17th century and became a founding
principle of modern science. For example, a probability-cloud diagram
of seed dispersal depicts how 'chance' (in the new, modern sense)
determines aspects of normal ecological dispersal. On the other hand,
'chance dispersal' uses chance in the old sense of 'factors beyond our
understanding' or 'given enough time anything can happen'; 'chance'
here is a very different concept and is not a real explanation for
anything."
Chance or probability, as used by anybody outside of casino amateurs,
is the likelihood of an event happening in a given period. So it may
or may not happen and you have no way of knowing if it will for sure.
So yes, I agree, it is beyond our understanding why one particular
gravid fly in a million successfully crossed an ocean. But overall
every fly had a "chance" which, with the appropriate data, can be
determined. And since this is used in physics and they are doing
nicely with it, I have no problems using it myself.

Best

Jason


On 28 March 2014 21:46, Michael Heads <m.j.heads at gmail.com> wrote:
> Hi Jason,
>
> I wrote: "The difference between normal, observed dispersal discussed by
>
> ecologists (e.g. weeds dispersing into a garden), and chance, 'jump'
> or 'long distance' dispersal as invoked by evolutionists, is that the
> former does not involve differentiation, whereas the latter is
> proposed as a mode of speciation."
>
> You replied: "Not true and no different (except in scale that is). We may
> argue
>
> about the actual probability the range of dispersal, but dispersal is
> a probability curve with a long tapering tail with increasing
> distance." No - that's normal, observed ecological dispersal. Long-distance
> dispersal inferred from a phylogeny does not work like that - it can happen
> anywhere, at any time. It is not correlated with any other factor (wind,
> currents etc.) and in many lineages it is inferred to occur only once in
> tens of millions of years and
>
> I said: "Note that the dispersal invoked in vicariance theory is caused by
>
> geological change, whereas dispersal as invoked by dispersal theory to
> explain allopatry, is caused by chance."
> You replied: "So you think chance is somehow wrong? You need to elaborate".
>
> The new, revolutionary idea of chance as a calculated probability began with
> Pascal and Fermat in the 17th century and became a founding principle of
> modern science. For example, a probability-cloud diagram of seed dispersal
> depicts how 'chance' (in the new, modern sense) determines aspects of normal
> ecological dispersal. On the other hand, 'chance dispersal' uses chance in
> the old sense of 'factors beyond our understanding' or 'given enough time
> anything can happen'; 'chance' here is a very different concept and is not a
> real explanation for anything.
>
> Michael
>
>
>
>
>
>
>
> On Thu, Mar 27, 2014 at 1:09 AM, JF Mate <aphodiinaemate at gmail.com> wrote:
>>
>> John, sorry for the delay in replying.
>>
>> "Historical reconstructions are hypotheses. I am not aware of
>> geological hypothesis made from geological research necessarily
>> falsify of an incongruent prediction (hypotheses) made from
>> biogeography. But it is not a simple case of geology/genes/phylogeny
>> being wrong. In fact, as shown in Heads' book, it is not a simple
>> matter of geology/genes/phylogeny being 'wrong' but in how they may be
>> interpreted."
>>
>> Your priors are limited to tectonics. Ergo, everything to you looks
>> like a nail so your interpretations are limited to the scenarios you
>> are willing to contemplate. It's like living in Flatland, you only see
>> some dimensions.
>>
>>
>> "Panbiogeography looks to correlation with geomorphology rather than
>> historical hypotheses."
>>
>> Biogeography in general looks at the correlation between distribution
>> patterns, phylogeny and then looks for mechanisms to account for this,
>> geology and dispersal. Thus it is not the sole domain of
>> pnabiogeography. The difference is that Panbiogeography does not
>> contemplate dispersal because, me thinks, that would make the results
>> fuzzier and therefore would make it impossible to justify the
>> tautology that in the bottom it has become: biogeography predicting
>> geology and viceversa.
>>
>> "Panbiogeography looks at the spatiality of genes (whether in
>> molecular or morphogentic form) rather than their interpretation as
>> absolute molecular clocks based on misrepresenting minimal divergence
>> dates as absolute or maximal, and looks to the spatiality of phylogeny
>> to examine patterns of common connections and breaks rather than as
>> imagined centers of origin. Molecular divergence estimates have been
>> widely hailed as the falsification of panbiogeography and yet it is
>> the divergence estimate that rested on the false representation as
>> absolute or maximal dating rather than minimal."
>>
>> Ken has already told you that your desire to stretch maximal dates to
>> fit (no, shoehorn) your only contemplated mechanism (tectonics) would
>> often lead to ridiculous scenarios. Phylogeny calibration is as good
>> as the calibrating points so it is work in progress, but rather useful
>> when comparing relative timings within the phylogeny. Thus, it is very
>> likely that many lineages will, in time, be shown to be older than
>> initially estimated. However it is mystifying to me how it can be used
>> it to justify their position. We can only talk of the data that we
>> have, not the data that can possibly exist. Thus Panbiogeography asks
>> for the impossible, that other biogeographers prove that a fossil does
>> not exist. This is what I mean, in part, about Panbiogeography being
>> unfalsifiable.
>>
>>
>> "Panbiogeographic analysis demonstrates that vicariism is
>> pervasive..." No, panbiogeographic analysis is a hammer and only sees
>> nails.But when you find a screw you insist it must be a nail.
>> Vicariance is common, that's all.
>>
>> "... and patterns of vicariism are shared by "good" and "poor"
>> dispersers."
>> How do you define good an bad disperser if, according to you, they do
>> not exist? In any case, what is the significance of your statement? We
>> are talking about succesful dispersal, which is random and likely a
>> combination of factors.
>>
>> "This makes the theory of chance (extraordinary) dispersal
>> problematic." Are you seeking some sort of meaning in nature? As to
>> equating chance and extraordinary as equal, playing
>> dice is a game of pure chance but not extraordinary. It is the
>> combination of probabilities that would make it highly unlikely
>> (extraordinary). Successful dispersal becomes more unlikely with
>> increasing distance, the degree of tapering of which is likely
>> taxon-specific. So unlikely yes, but extraordinary is a choice of
>> words as poor as "miraculous" or "mystifying".
>>
>> "If an organism is said to cross a "barrier" how does one know that it
>> is a barrier."
>> Normally, something like this: if it dies there with a certainty of a
>> 100%, it is a barrier, if survival is equivalent to its normal
>> habitat, it is not and in between you have a fuzzy area. I guess that
>> is why Stephen thinks dispersal is more relevant in the pacific
>> islands (more tightly defined barrier).
>>
>> "..In panbiogeography the question is less about dispersal and
>> vicariance being competing mechanisms as they are complimentary.
>> Biogeographers have traditionally invoked a concept of dispersal
>> (chance, long distance etc) by which to interpret biogeographic
>> patterns,..."
>> They have invoked dispersal as one of the mechanisms to explain biotic
>> distribution.
>>
>> "...but perhaps one could use biogeographic patterns to understand how
>> dispersal works in the evolution of vicariant distributions."
>> So we assume dispersal does not exist so we can use vicariance to
>> understand how dispersal works... even though it doesn´t exist? You
>> need to explain this a bit.
>>
>>
>> Michael
>>
>> "The difference between normal, observed dispersal discussed by
>> ecologists (e.g. weeds dispersing into a garden), and chance, 'jump'
>> or 'long distance' dispersal as invoked by evolutionists, is that the
>> former does not involve differentiation, whereas the latter is
>> proposed as a mode of speciation."
>>
>> Not true and no different (except in scale that is). We may argue
>> about the actual probability the range of dispersal, but dispersal is
>> a probability curve with a long tapering tail with increasing
>> distance. Also dispersal is but one mechanism leading to allopatry
>> (Mayr or Dobzhansky mention "barriers" emerging as well).
>>
>> "Dispersal theory explains range overlap by dispersal, but also
>> explains allopatry by dispersal. Vicariance theory explains range
>> overlap by dispersal, but explains allopatry by vicariance."
>> Dispersal is one mechanism to explain allopatry. Vicariance in
>> Panbiogeography is the only mechanism contemplated for reasons that
>> have been explained many times before by people far abler than me.
>>
>>
>> "Note that the dispersal invoked in vicariance theory is caused by
>> geological change, whereas dispersal as invoked by dispersal theory to
>> explain allopatry, is caused by chance."
>> So you think chance is somehow wrong? You need to elaborate.
>>
>> _______________________________________________
>> 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:
>> http://taxacom.markmail.org
>>
>> Celebrating 27 years of Taxacom in 2014.
>
>
>
>
> --
> Dunedin, New Zealand.
>
> My recent books:
>
> Molecular panbiogeography of the tropics. 2012. University of California
> Press, Berkeley. www.ucpress.edu/book.php?isbn=9780520271968
>
> Biogeography of Australasia:  A molecular analysis. 2014. Cambridge
> University Press, Cambridge. www.cambridge.org/9781107041028