[Taxacom] Meliaceae (vicariance??)

[Kenneth Kinman]

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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