Talk:Neomura

From Wikipedia, the free encyclopedia

WikiProject Tree of Life
Biology Portal
This article is within the scope of WikiProject Tree of Life, an attempt to better organise information in articles related to taxonomy and the phylogenetic tree of life. For more information, visit the project page.
Start This article has been rated as start-class on the quality scale.
Top This article has been rated as top-importance on the importance scale.

Article Grading: The article has been rated for quality and/or importance but has no comments yet. If appropriate, please review the article and then leave comments here to identify the strengths and weaknesses of the article and what work it will need.

Contents

[edit] Removed section

[edit] Variations of the Theory

"The current mainstream system of classification is the three-domain system. The common consensus is that Archaea and Eukaryota evolved on a seperate branch from Bacteria, with the root of life lying somewhere in between. This branch is Neomura. However, Cavalier-Smith has postulated that Bacteria is in fact paraphyletic to Neomura, meaning that Neomura evolved from Bacteria. According to this theory, Neomura is a group which evolved from Gram-positive bacteria, this transition being marked by twenty evolutionary adaptions, which accompanied, or derived from, two other important adaptions: the development of histones to replace DNA gyrase, and the loss of peptidoglycan cell walls to be replaced by other glycoproteins."

This is confusing because it's worded too technically. Rather than seeming to contradict what has just been said, you should start out by simply saying that Cavalier-Smith theorizes that the Archaebacteria and Eukaryotia arose from the Neomura which arose from the gram positive bacteria bacteria. You can then go on to say that the Bacteria are paraphyletic without the Neomura, but this phrasing used is rather awkward. I can't correct it without the article handy. I just can't seem to see what the second sentence is saying, so it's impossible to correct. I would simply like to see this clarified first, inserted into the article later. I don't have the article handy, but will try my best to read and understand as much as possible. KP Botany 19:00, 2 June 2007 (UTC)

It's not correct to say the Archaea and Eukaryota arose from the Neomura; they each are part of Neomura. (It's like saying that Primata evolved from Mammalia.) If the hypothesis that Archaea and Eukaryota form a clade is correct then there are three alternative sub-hypotheses: either both evolved from stem Neomura (Cavalier-Smith's hypothesis, but there may be others), or Eukaryota evolved from Archaea (making Archaea paraphyletic), or Archaea evolved from Eukaryota (making Eukaryota paraphyletic). (The last doesn't seem very likely.) Lavateraguy 21:22, 2 June 2007 (UTC)
I'm not debating what is the current hypothesis, I'm debating whether or not you've said or presented them. What you just said here does not in any way come through from this paragraph in the article, as there is no mention whatsoever that there are three alternative sub-hypotheses! I'm not actually getting what is being said here at all by this paragraph, so there's no point in debating any substantive issues--it has to be written so the reader can undertand what is being said, regardless of what is being said.
So, what is C-S saying about Archaea and Eukaryota? That they belong in clade together, called Neomure, that evolved from the gram-positive bacteria, which, together with the rest of the bacteria form a crown group? Is that all? Who offers the latter two hypotheses, the alternatives to both evoving from Neomura? Are these dismissed or discussed by C-S or by someone else (does Woess mention any of this)?
Please don't debate the issues of various theories with me, although I'm not sure that's what you're doing, but rather clarify this text to get across what C-S is saying in his paper. KP Botany 21:48, 2 June 2007 (UTC)
And now we're left with less than we started with. Hmmm. I think we need a professional. Werothegreat 18:30, 3 June 2007 (UTC)
It's not less if what was there was difficult for the reader to follow. An encyclopedia is written for its readers--if it's wrong, it's not more, if it's not written for the general audience, it's not more, if it can't be followed accurately, it's not more. We always need the assistance of professionals on articles, particularly in areas outside of the multicellular eukaryotes when it comes to organisms. You, Werothegreat, however, read enough T C-S to rewrite this one little section--give it a try. KP Botany 19:37, 3 June 2007 (UTC)

[edit] Wikispecies link?

Why is there a wikispecies link? They're still mucking about in 4-eukaryote-kingdom-land. There is no Neomura article in wikispecies. Werothegreat 01:53, 17 July 2007 (UTC)

They have both Cetartiodactyla and Artiodactyla articles. They don't explain that only let write articles from one source. If a taxon exists it must have an article for explaining what it is. 83.45.216.23 17:45, 17 July 2007 (UTC)
What? Artiodactyls are mammals. We're talking about the supergroup that contains Archaea and Eukarya. There is no page on wikispecies for it, so there is no need for a wikispecies link at this time. Werothegreat 01:49, 18 July 2007 (UTC)
I don't see the difference between having two incompatible proposed clades at ordo level and at superdomain level. 80.30.232.210 18:10, 18 July 2007 (UTC)
It isn't incompatible. There just ISN'T A PAGE FOR IT ON WIKISPECIES YET. So there is no point to have a wikispecies link to a page that does not exist. Werothegreat 17:46, 19 July 2007 (UTC)

[edit] Origin of eucaryotes

The section "History of Taxon" implies that the first stage in the evolution of eucaryotes was the incorporation of aerobic bacteria into some species of archea to form mitochondria. AFAIK it is generally agreed that the first stage was the incorporation of spirochetes into some species of archea to form micro-tubules. Sorry, can't give a ref (most annoying as I was looking at one earleir today). Philcha (talk) 23:12, 20 January 2008 (UTC)

There's more than one hypothesis about the origin of eukaryotes. You might be thinking of Margulis'. (Margulis et al, The chimeric eukaryote: Origin of the nucleus from the karyomastigont in amitochondriate protists, PNAS 97(13): 6954-6959 (2000). This has the problem that there are no living primitively amitochondriate eukaryotes - the earlier opinion that there were arose from overlooking vestigal mitochondria in some taxa, combined with long branch artefacts in 18S RNA cladograms.) Cavalier-Smith proposes the existence of non-mitochondriate stem eukaryotes, but, IIRC, he doesn't postulate a symbiotic origin from these. (The problem with his hypothesis is that he has Neomura as a relatively young clade deeply nested in Eubacteria, as shown in the tree in the article, and has to explain the apparent existence of older red algae. Eukaryotes arising from symbiosis of an Archaean and a Proteobacteria is, I think, Woese's hypothesis.
It was not my impression that symbiotic origin of organelles other than mitochondria and plastids (and the "cyanelle" of Paulinella) was generally accepted. Lavateraguy (talk) 23:40, 20 January 2008 (UTC)

The spirochete hypothesis has been pretty much discredited. The actiniobacterial absorption of an alpha-proteobacteria is the industry standard. Werothegreat (talk) 12:58, 19 February 2008 (UTC)