[Taxacom] Meliaceae (vicariance??)
John Grehan
calabar.john at gmail.com
Fri Nov 15 13:37:14 CST 2019
2019
As noted in my original email, the vicariance example was for those
interested in such processes. But Ken's comments do offer scope for further
discussion and so I have inserted my perspectives on those comments below
for those interested.
“There is already lots of published evidence that a considerable amount of
dispersal occurred in this case. Panbiogeographers just dismiss all of it
with the same old arguments about fossil calibration errors.�
Ken, you totally misundertand the panbiogeograhic objection. It is NOT
about calibration errors, it is about transmogrifying minimum dates from
fossil calibrations into actual or maximal dates. This is just
scientifically not possible. Therefore we do indeed dismiss
misrepresentation of minimums as maximums. Quite rightly so. That is
science.
“If they would only widen the taxonomic context (as I did in the
Lepidoptera-Trichoptera posts on November 4th)�
Ken, I think that's a little disingenuous given that the published
panbigoeographic studies cover a huge swath of taxa.
“perhaps they would realize that the evidence presented by dispersalists is
good science (not to be dismissed with the same old tired arguments).�
There is nothing 'tired' about correctly pointing out that making maxiums
ages out of minimums is neither scientific or valid.
Go beyond the Meliaceae-Simaroubaceae-Rutaceae clade, and you are likely
to see how evidence from outgroup relatives fits better with dispersal than
with vicariance.
“Muellner-Riehl et al. (2016) proposed that Sapidales arose about 112
million years ago, and that the two subfamilies of Meliaceae split as early
as 89.8 million years ago.�
If this is fossil based calibration then these dates are minumums only.
“This fits in pretty well with the recent 2018 (Atkinson, 2018) report of a
stem-lineage fossil of Meliaceae dated at 79 million years ago, and the
stem-lineage could easily go back more than 10 million years before that
fossil.�
Could easily go back more than 10 million years – agreed! Of course! That
is the nature of fossils.
“But that still does not mean it goes back far enough that vicariance
explains the biogeography of Family Meliaceae. Africa and South America
separated much earlier (about 140 million years ago), and they had
separated from East Gondwana about 180 million years ago. Arguments seem
unconvincing blaming an imagined poor fossil record that far back.�
This gets to Ken's personal belief about how much older a taxon can be. But
this is about his beliefs and he is welcome to them, but they cannot be
scientifically contested unless there is some scientific basis specified
for that belief. One time people thought that trains could never go faster
than 20 miles an hour.
“ center of origin in Africa of Family Meliaceae makes more sense (about
85-90 million years ago), although an origin in Eurasia is also possible.�
Anything is possible. Biogeographic analysis is about what reconstuction is
conssitent with the evidence. Otherwise one would do no science.
“It would then have expanded north into Europe and from there into North
America before they separated about 80 million years ago.�
If that happened, but there is no empirical evidence for a center of origin
or dispersal sequence for this group.
“herefore, with the stem-lineage fossil of Meliaceae (Atkinson, 2018) in
North America at 79 million years ago, one would expect that they had
spread from Africa into Europe about 80-85 million years ago.�
Only if one has this belief.
“The eastward expansion through southern Asia could have begun about the
same time (but didn't reach Australia until much much later, so Rutaceae
could have claimed SW Australia first and competitive exclusion kept
Meliaceae out). Competitive exclusion could also explain the absence of
Meliaceae in Hawaii.�
Point missing here is that the patterns of absence apply broadly to other
taxa. Not only is there no evidence for competitive exclusion of one before
the other, it is not even necessary.
On Fri, Nov 15, 2019 at 2:02 PM Kenneth Kinman via Taxacom <
taxacom at mailman.nhm.ku.edu> wrote:
> Hi All,
> There is already lots of published evidence that a considerable
> amount of dispersal occurred in this case. Panbiogeographers just dismiss
> all of it with the same old arguments about fossil calibration errors. If
> they would only widen the taxonomic context (as I did in the
> Lepidoptera-Trichoptera posts on November 4th), perhaps they would realize
> that the evidence presented by dispersalists is good science (not to be
> dismissed with the same old tired arguments). Go beyond the
> Meliaceae-Simaroubaceae-Rutaceae clade, and you are likely to see how
> evidence from outgroup relatives fits better with dispersal than with
> vicariance.
> Muellner-Riehl et al. (2016) proposed that Sapidales arose about
> 112 million years ago, and that the two subfamilies of Meliaceae split as
> early as 89.8 million years ago. This fits in pretty well with the recent
> 2018 (Atkinson, 2018) report of a stem-lineage fossil of Meliaceae dated at
> 79 million years ago, and the stem-lineage could easily go back more than
> 10 million years before that fossil. But that still does not mean it goes
> back far enough that vicariance explains the biogeography of Family
> Meliaceae. Africa and South America separated much earlier (about 140
> million years ago), and they had separated from East Gondwana about 180
> million years ago. Arguments seem unconvincing blaming an imagined poor
> fossil record that far back.
> A center of origin in Africa of Family Meliaceae makes more sense
> (about 85-90 million years ago), although an origin in Eurasia is also
> possible. It would then have expanded north into Europe and from there
> into North America before they separated about 80 million years ago.
> Therefore, with the stem-lineage fossil of Meliaceae (Atkinson, 2018) in
> North America at 79 million years ago, one would expect that they had
> spread from Africa into Europe about 80-85 million years ago. The
> eastward expansion through southern Asia could have begun about the same
> time (but didn't reach Australia until much much later, so Rutaceae could
> have claimed SW Australia first and competitive exclusion kept Meliaceae
> out). Competitive exclusion could also explain the absence of Meliaceae
> in Hawaii.
> -----------Ken Kinman
>
> Muellner-Riehl et al. 2016
> https://onlinelibrary.wiley.com/doi/abs/10.12705/655.5
>
> Atkinson, 2018:
>
> http://2018.botanyconference.org/engine/search/index.php?funcÞtail&aid27
>
> Koenen et al., 2015
> https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.13490
>
>
>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>
>
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