Taxacom: Brachiopoda close to Mollusca (was: Mollusca trees (as well as Arthropoda) seem to still suffer from misrooting)

Wed Sep 21 17:21:48 CDT 2022

Hi All,
       Although Phylum Bryozoa was my second choice for rooting the molluscs, the following research paper was brought to my attention, putting forth various evidence indicating that bryozoans might actually be closer to molluscs than brachiopods:
Bryozoan Studies 2001; "Deconstructing bryozoans" by Dewel, Winston & McKinney.  One quote (on page 94) regarding bryozoans: "the pattern of cilia on adult tentacles and the larval ciliary ridge is remarkably similar to that on bivalve gills (Nielsen, 1987)"

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From: Taxacom <taxacom-bounces at lists.ku.edu> on behalf of Kenneth Kinman via Taxacom <taxacom at lists.ku.edu>
Sent: Sunday, September 18, 2022 10:46 AM
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Subject: Taxacom: Brachiopoda close to Mollusca (was: Mollusca trees (as well as Arthropoda) seem to still suffer from misrooting)

Dear All,
      Until now I have never suggested what taxa might best be used to root molecular trees for the Mollusca.  But I have long thought the best choice would be members of Phylum Brachiopoda (or perhaps another lophophorate phylum Bryozoa).  If Bivalvia are actually the earliest molluscs, then the brachiopod lophophorates would be an excellent choice (since they too are bivalved).  One might also use (or include) bryozoan lophophorates in the outgroup to Mollusca, especially bryozoans with cyphonautes larvae (which are also bivalved).   Using such lophophorate taxa to root molluscan molecular trees would be better than using ecdysozoans (such as arthropods), because ecdysozoans seem to be a lot less closely related to Mollusca, and I strongly suspect Lophotrochozoa is actually paraphyletic with respect to Ecdysozoa (not sister groups).  Very small Brachiopoda and Bivalvia would have coexisted among the worldwide "small shelly faunas" of the Upper Precambrian and Lower Cambrian, and they would have been preceded by their unmineralized ancestors.
       Anyway, I just discovered a 2017 research paper showing Mollusca as sister group to "Kryptrochozoa" which includes Brachiopoda and Phoronida.   This makes me even more confident that Brachiopod sequences could be the best to use to root molluscan molecular phylogenies.  And the authors state: "We show that lophotrochozoans share many gene families with deuterostomes, suggesting that these two groups retain a core bilaterian gene repertoire that ecdysozoans (for example, flies and nematodes) and platyzoans (for example, flatworms and rotifers) do not."  Perhaps this also indicates that using ecdysozoans to root Mollusca could result in mis-rooting (and especially if the ecdysozoans used are very derived).  So if one wants to try exploring and thinking "outside the box", using lophophorates as outgroup to molluscan molecular phylogenies might yield some very interesting results, and even revolutionize our understanding of the evolution and interrelationships of Bilaterian phyla.  Here's a weblink to the 2017 research paper:

https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41559-017-0389-y&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cbc9040a6534b4e88e5b008da9c1fada6%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637993957259552113%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=M8BLwOk6utaoz3IXuQVaQEUdWJYJcVCwVsJjqRkL%2Fz0%3D&reserved=0
[https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmedia.springernature.com%2Fm685%2Fspringer-static%2Fimage%2Fart%253A10.1038%252Fs41559-017-0389-y%2FMediaObjects%2F41559_2017_389_Fig1_HTML.jpg&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cbc9040a6534b4e88e5b008da9c1fada6%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637993957259552113%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ZYvPJYZmnxnKTLaZtfsice0BJcQLm%2FRLURxr1VoFf%2Bs%3D&reserved=0]<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41559-017-0389-y&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cbc9040a6534b4e88e5b008da9c1fada6%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637993957259552113%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=M8BLwOk6utaoz3IXuQVaQEUdWJYJcVCwVsJjqRkL%2Fz0%3D&reserved=0>
Nemertean and phoronid genomes reveal lophotrochozoan evolution and the origin of bilaterian heads - Nature Ecology & Evolution<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.nature.com%2Farticles%2Fs41559-017-0389-y&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cbc9040a6534b4e88e5b008da9c1fada6%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637993957259552113%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=M8BLwOk6utaoz3IXuQVaQEUdWJYJcVCwVsJjqRkL%2Fz0%3D&reserved=0>
Lophotrochozoans represent more than one-third of known marine animals and play important ecological roles 1.It is widely accepted that they comprise a major protostome clade, although the clade ...
https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.nature.com%2F&data=05%7C01%7Ctaxacom%40lists.ku.edu%7Cbc9040a6534b4e88e5b008da9c1fada6%7C3c176536afe643f5b96636feabbe3c1a%7C0%7C0%7C637993957259708316%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=Y2D9LOUgYgagVBj2LyYHNgBYPcp4WHDmh5o%2Fw4NqlCQ%3D&reserved=0


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From: Taxacom <taxacom-bounces at lists.ku.edu> on behalf of David Campbell via Taxacom <taxacom at lists.ku.edu>
Sent: Thursday, September 15, 2022 3:53 PM
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Subject: Re: Taxacom: Mollusca trees (as well as Arthropoda) seem to still suffer from misrooting

Paleontological, anatomical, and genomic data strongly support the
conventional understanding.  Bivalves are not the basal mollusks, they are
not paraphyletic to other extant mollusks, and euthyneuran gastropods are
derived within gastropoda, not giving rise to other groups.  Radulae have
been lost numerous times within the Mollusca.  The paleontological evidence
points to single-part shells deriving from multipart.  It's not explainable
by misrooting, as rooting is based on including other phyla, not on
assuming a configuration within Mollusca,

--
Dr. David Campbell
Associate Professor, Geology
Department of Natural Sciences
110 S Main St, #7270
Gardner-Webb University
Boiling Springs NC 28017
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