What is best current estimate of eukaryote evolutionary tree? (Adl, Corliss ?)
Robert Maas, http://tinyurl.com/uh3t
(Entoprocta Phoronida Ectoprocta Bryozoa) and tried a Google search
to get more info, and found two pieces of incomplete information:
Several references including <http://www.treesearch.fs.fed.us/pubs/30101>
report that Adl has proposed an organization of 6 major groups
above phylum level, none of which I've been able to find listed online.
Other references including
<https://www.researchgate.net/publication/16800216_The_kingdom_Protista_and_its_45_phyla>
report that Corliss has proposed an organization of 18
supraphyletic groups, of which only the first 7 (rhizopods,
mastigomycetes chlorobionts euglenozoa rhodophytes cryptomonads
choanoflagellates) are explicitly listed before "ABSTRACT TRUNCATED
AT 400 WORDS".
It's possible that the 18 groups are a finer division consistent
with the 6 larger groups, but I have no idea if that is the case or
of these two researchers are directly disagreeing with each other
in their proposed classification systems. Does anybody in this
newsgroup have access to the full list of either Adl's 6 or
Corliss's 18? Does anyone advocate yet a third current proposed
classification system for eukaryotes?
Back to the original question I was researching, I saw conflicting
research results, one claiming that Bryozoa = Entoprocta + Ectoprocta
is monophyletic (one entire clade), and another claiming to refute
that theory, claiming instead that Entoprocta + Phoronida are
sister clades only distantly related to Ectoprocta hence "Bryozoa"
is not a valid name except if redefined to be nothing but a synonym
for Ectoprocta, which I find disagreeable. In particular, despite
the fact that Entoprocta don't have a coelum whereas Ectoprocta do,
one author claims this have/notHave coelum feature is "plastic",
that it's relatively easy for evolution to make it come and go over
time, rather than being an essential feature that is nigh
impossible to change hence must have been fixed very early between
two different clades which later each diverged to modern phyla.
Does anybody here know of any good resolution of this question, or
is this still undecided? Common sense says that the split between
developing a coelum or not developed very early and can't switch
back and forth during recent evolution, but common sense isn't
always right. (That's why we have science!)
..
mafarmerga
Robert,
I am a senior co-author on the Adl et al. 2005 paper. John Corliss is
retired and no longer well enough to comment on this topic, but having
known him for nearly 30 years I am well familiar with his work.
The Bryozoa (either narrowly or broadly defined) are metazoa and thus
are, strictly speaking, not considered protists. Protists being
eukaryotes that are not clearly metazoa, fungi, or vascular plants.
Not a satisfying definition I know, but it is essentially how we now
use the term.
Thus the Bryozoa are not protists, although the closest metazoan
relatives, the choanoflagellates, are protists. Sponges are metazoa.
All of them, metazoa + choanoflagellates + fungi + DRIPS (a group of
related protists) are members of the supergroup Opisthokonts, (single
posteriorly located cilium being the apomorphy of the clade). The
Opisthokont clade, with metazoa/choanoflagellates being sister to the
fungi, is very well supported by a variety of molecular sequence
analysis.
I am out of my comfort zone talking about metazoan phylogeny so I
cannot address your very specific and interesting question of
bryozoans. I just know that we (and Corliss) no longer consider them
to be "protists"
Hope that helps.
Robert Maas, http://tinyurl.com/uh3t
> I am a senior co-author on the Adl et al. 2005 paper.
Wow! I found "THE MAN" for this topic!
> John Corliss is retired and no longer well enough to comment on
> this topic, but having known him for nearly 30 years I am well
> familiar with his work.
So it looks like unless Adl shows up in this newsgroup, or
otherwise contacts me, you are my one and only really-good source
on this topic. (If he contacts me, I'll have two equally good sources.)
> The Bryozoa (either narrowly or broadly defined) are metazoa and
> thus are, strictly speaking, not considered protists.
Sorry about the typo in my posting to start this thread. I was
thinking about two different topics, protists ("protoctists" per
Margulis 1987), and the several phyla of animals whose polyps do
filter-feeding and/or small-prey catching using what looks like
tenticles sticking off the end opposite the attachment point. For
unknown reason (mental lapse?) I started to compose a question
about protists, and got that key word typed, but then switched to a
question about those animals, and never noticed (until you
mentionned it) that I had left the wrong keyword in there.
> Protists being eukaryotes that are not clearly metazoa, fungi, or
> vascular plants. Not a satisfying definition I know, but it is
> essentially how we now use the term.
Yeah, not exactly consistent with cladistics. But per a whole
*different* way I've conceived for classifying life, it actually
makes sense (except that kelp et al are true multi-tissue *plants*,
not in the same clade as Plantae, but "high" lifeforms in the same
sense as vascular plants, so each clade of such true multi-tissue
algae ought to be a "kingdom" on par with vascular plants). My idea
is that the primary organization should be per heirarchy of
structure. DNA or RNA is within cells, so cells are a higher level
of structural complexity than viruses. Prokaryotes are
endo-symbionts (as demonstrated by Margulis in her other famous
book) within Eukaryotes, so Eukaryotes are a higher level of
structural complexity than Prokaryotes. Primitive eukaryotes plus
photosynthetic bacteria form algae, so algae are higher than
non-photosynthetic eukaryotes. Plantae are endosymbionts of algae
and primitive eukaryotes, so Plantae are another step above algae.
Metazoa are composed of cells, so Metazoa are higher than
zooplankton, along a branch different from algae. Kelp is higher
than uni-cellular phytoplankton, thus higher than ucp along a
branch different from Plantae. This all produces a DAG (directed
acyclic graph, almost a tree) of complexity, something like:
/-----> Plantae
/--> UniCellAlgae----> Kelp
/------\ / \
DNA/RNA/Viruses -> Prokaryotes Protoctists -> Fungi ->> Lichen
\------/ \---> Metazoa
Now within each type of complexity, we plot evolutionary trees, as
a separate dimension. It makes no sense to plot evolutionary trees
from one type of complexity to another, because an endosymbiosis
**breaks** the paradigm of a tree. The best we can do is identify
the points in one complexity-kind that merged together to form the
base of the evolutionary tree at a next-higher level of complexity.
For example, some purple sulfur bacteria probably merged with some
other prokaryote to form the base of the Eukaryote tree, the psb
forming the mitochondrion and the other forming the nucleus, the
mitochrondrion losing much of its DNA to the nucleus but still
having some that it can't give up because of the different genetic
code it depends on, and a spirochete might have been a third member
of that endosymbiosis as Margulis proposed, the spirochete forming
the spindle for mitosis, but losing *all* its DNA to the nucleus
already so we can no longer be sure it ever was an independently
living cell.
(Something I discovered by researching WikiPedia during composition
of this article: Alternate theory as to why some genes stay in
mitochondria, rather than trouble with different genetic code:
http://en.wikipedia.org/wiki/CoRR_Hypothesis)
Note that I sub-organize the structure of Plantae Kelp and Metazoa
as follows:
UniCellKelp-->KelpTissue-->KelpWholeLifeform
UniCellPlantae-->PlantaeTissue-->PlantaeSystems-->PlantaeWholeLifeform
UniCellAnimal-->AnimalTissue-->AnimalOrgan-->AnimalSystem-->AnimalWholeLifeForm
The same idea of diagramming increasing complexity can also include
ecosystems which are "higher" organization than any single
life-form, and "hive" societies such as Hymenoptera.
> Thus the Bryozoa are not protists, although the closest metazoan
> relatives, the choanoflagellates, are protists.
Yes, per my way of analyzing it, Bryozoa et al and all other
Metazoa are more complex than any Protists, because they form
multiple types of tissue (and all but Placozoa and Porifera combine
tissues to form organs etc.), separating reproductive cells (which
are immortal) from somatic cells (which sacrifice themselves on
behalf of the reproductive cells, per Dawkins "selfish gene"
kin-cooperation). Kelp likewise form separate tissues, as do
Plantae and Fungi.
When I first read Five Kingdoms, I was totally uncomfortable with
the non-cladistic way of branching Plantae/Animalia/Fungi from
Protoctist root. But now with my levels-of-complexity as the most
fundamental classification system, I'm all for that distinction
even moreso. Note that we don't have three domains (Archaea,
Eubacteria, Eukaryota). Instead we have all the kinds of complexity
I diagrammed above, and within single kinds of complexity we have
"kingdoms" as follows:
Prokaryotae = Archaea + Eubacteria
endosymbiosis(Eubact.myxobacteria + Archae.methanogenic) -> FirstPreEukaryote
endosymbiosis(FirstPreEukaryote + Eubact.Proteobacteria) -> FirstTrueProtist
Note: One other new theory I discovered while researching for this reply:
http://en.wikipedia.org/wiki/Hydrogen_hypothesis
basically claims the mitochondrion was the *first* endosymbiosis,
thus forming the first eukaryote, rather than it coming later
(after the nucleus already existed in the cell) as I assumed above.
> Sponges are metazoa.
Yes, the key (other than formation of a blastula) is that they
undergo permanent cell differentiation, unlike simple colonial
protists, so I agree. Sorry again about my typo that got you
beating a dead horse.
> All of them, metazoa + choanoflagellates + fungi + DRIPS (a group
> of related protists) are members of the supergroup Opisthokonts,
> (single posteriorly located cilium being the apomorphy of the
> clade).
Now *this* is something I hadn't heard before. Looking up the term
in Google -> WikiPedia: http://en.wikipedia.org/wiki/Opisthokont
paraphrase: Opisthokont = Animalia + Fungi + Choanozoa + Mesomycetozoa
Margulis had choaoflagellates within phylum Zoomastigina.
So does Choanozoa equate with *all* of Zoomastigina or just part?
If just part, then is Zoomastigina *not* a clade, thus it's a
"false phylum"? Quoting from Margulis (1987) "Each bears at least
one undulipodium; some bear thousands." In the second paragraph
Margulis admits the first five of eight classes, including
"choanomastigotes", might not be related to the other three. So is
here second-paragraph caveat now known to be true, choanomastigotes
= Choanozoa = choanoflagellates were indeed misplaced when they
were put with the Zoomastigotes, and belong instead with the
Opisthokonts? Her 3 photos and 1 diagram, of Staurojoenia Joenia
and Trichonympha, all have many hairy things (undulipodia I
presume), unlike Opisthokonts.
http://www.multicellgenome.com/Lab/Opisthokonta.html
lists a few more of the other members of this clade:
"choanoflagellates (Choanoflagellata), ichthyosporeans (Ichthyosporea;
also termed Mesomycetozoea), nucleariids (Nucleariidae),
Corallochytrium, Ministeria, and Capsaspora owczarzaki"
I assume most of those (except Fungi/Animal/Choano) are in your "DRIPS"?
I'll have to look up "DRIPS" separately if I can.
Quoting again:
"nucleariids constitute the unicellular
lineage most closely related to fungi, whereas the remaining
unicellular opisthokonts (choanoflagellates, ichthyosporeans,
Ministeria, Corallochytrium and Capsaspora) are decidedly more closely
related to animals than to fungi"
http://www.experiencefestival.com/opisthokonts
Eukaryotic flagella are supported by microtubules in a characteristic
arrangement, with nine fused pairs surrounding two central singlets.
Calling these "flagella" is so confusing! These are clearly
*undulipodia* as explained and diagrammed so clearly by Margulis in
Five Kingdoms (1987) pages 9 and 11. Why aren't other people using
her term? Too much of a tongue twister? Then why not "cilium"?
> The Opisthokont clade, with metazoa/choanoflagellates being
> sister to the fungi, is very well supported by a variety of
> molecular sequence analysis.
Yeah, the several Web pages I viewed (cited above) agree with you.
Thanks for enlightening me. This in fact answers my *other*
question, of the primary cladistics for protists. Thanks for
enlightening me.
> I am out of my comfort zone talking about metazoan phylogeny
Wait a minute there! You're co-author with Adl of the proposition
that metazoa divide into six super-phyla clades, right? So you must
have a copy of the info there somewhere, right? So could you please
list the six, and also give some idea how these six relate to some
of the traditional (Margulis) 33 phyla of Animalia?
> so I cannot address your very specific and interesting question
> of bryozoans.
Now *that* you may indeed be unable to answer, if the best theory
currently is that *all* of those phyla (Entoprocta, Phoronida,
Ectoprocta, Brachiopoda) are in fact within a single (1) of your
six super-phyla groups, so your studies go down only to the level
of those six groups, not deep inside any one of them. But for that
to be true, that single super-phyla group would have to include
both pseudo-coelum (Entoprocta) and true-coelum (Ectoprocta,
Brachiopoda), unless having a coelum is "plastic" as one person
claimed. I'm currently favoring sticking with Margulis 1987 on this
point (improved slightly by discovery of clade Lophophorata):
Bilateria
+--Acoelomates (4 phyla)
+--Pseudocoelomates
| +--Entoprocta
| `---etc. (7 other phyla)
`--Coelomates
+--Proterostomes
| +--Lophophorata
| | +--Phoronida
| | `--Brachiopoda
| +--Ectoprocta
| +--Mollusca
| +--Arthropoda
| `--etc. (7 other phyla)
`--Deuterostomes
> I just know that we (and Corliss) no longer consider them to be "protists"
I doubt you or anyone *ever* did, except by typo, sorry again.
By the way, I got so fascinated by the images I found by Google
image search that I collected several representative examples and
shrunk to fit my one-inch cellphone screen:
http://www.rawbw.com/~rem/WAP/phyla.html
In collecting those images I noticed something I hadn't noticed
before: Phoronida always form mirror-image twins. So they don't
arbitrary spiral one way or the other, they spiral *both* ways in
parallel, vaguely analagously to the multi-verse solution to
alternative choices in quantum mechanics! (Or the only
mathematically consistent solution to the constraints of strict
bilateral symmetry and spiral tentacles.)
Another thing I noticed is the very wide variety of forms of
colonial growth of Ectoprocta compared to a paucity of variety in
both Phoronida and Entoprocta. Apparently Entoprocta's survival
strategy is rather like bacteria and fungi: Shrink size and avoid
complexity, for efficiency, and use that efficiency to quickly
colonize every surface that is available, also like spambotnets. By
comparison Ectoprocta makes a larger investment in each single
organism, and specializes differently for each niche, rather like
Arthropoda and Chordata. Ectoprocta fascinate me now!
..