Taxacom: Phylogeny of Phylum Mollusca

[Paulo A. Buckup]

Dear Ken,
      What exactly is the problem with the outgroup and how does it
influence affect the topology of the genomic cladogram? I am not an expert
in molluscs, but usually statistical molecular algorithm such as maximum
likelihood and Bayesian applications  do not rely on outgroups for rooting
the tree. They usually rely on genetic distances on an unrooted network and
root threes in the midpoint.of the distances. Did the molecular study
forced the ingroup to be monophyletic?
      Please explain how genomic data can be biased by inclusion of
outgroup samples.
Cheers

Paulo Buckup

Em dom., 20 de jul. de 2025 ?s 23:21, Kenneth Kinman via Taxacom <
taxacom at lists.ku.edu> escreveu:

> Hi All,
>      I have been looking for recent molecular evidence regarding the
> origin and evolution of Phylum Mollusca.  I found one recently published a
> few months ago (see weblink below).
>       Unfortunately from my perspective, it suffers from the same
> fundamental problem that previous studies have suffered, namely the very
> poor choice of outgroups.  If you include groups for outgroups which
> actually turn out to be ingroups to Phylum Mollusca, the phylogeny
> presented is automatically fatally flawed.  This has been a persistent
> problem ever since molecular evidence has been used (for decades) to
> determine the phylogeny of Phylum Mollusca.   The ancestors of Phylum
> Mollusca lie in some very small "shelly fauna" of the Precambrian (which
> are extremely poorly known), not in any Cambrian molluscs which evolved
> long after.
>      As I have argued previously, if inappropriate outgroups are used, the
> results are extremely misleading, and that it is actually "morphological
> evidence", not such misleading molecular conclusions, that makes more
> sense.   I realize this is still a minority view that Phylum Bivalvia gave
> rise to the other molluscan phyla, but a view that has not been evaluated
> properly.  The majority seem to rely on every new analysis which is again
> based on inappropriate outgroups.  The weblink below is just the most
> recently example.
>                     -------------Ken Kinman
>
>  https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.science.org%2Fdoi%2F10.1126%2Fscience.ads0215&data%7C02%7Ctaxacom%40lists.ku.edu%7C8bbeb50353cd4ccbf3b108ddc85932ee%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638887007610311937%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=1%2Bo1sb4X0GNHkYzplMRtpiB1wxsD%2FCA4HLOxxlVtzjM%3D&reserved=0
>
>
>
>
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-- 

Paulo A. Buckup, Ph.D.         https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Flattes.cnpq.br%2F7200068520418368&data%7C02%7Ctaxacom%40lists.ku.edu%7C8bbeb50353cd4ccbf3b108ddc85932ee%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C638887007610341500%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=Rr5Sey2qe4nS%2FALWlKFil%2F%2Fu%2BCui55yMG%2F6iNB%2Bdskg%3D&reserved=0

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