Talk:Eukaryote

Protista

• I fully recognize the problems here. One way it could be handled is to put in parentheses after Protista in the taxobox something like - (metakingdom) to indicate it's not really normal, and let people go to the Protista page for further breakdown. What both classical taxonomy and cladistics do clearly share is hierarchy, and I think we should do our best to blend these. The reasons are these:
  • First, people mentally organize information logically, and when there are certain fixed categories, it's easier for people to conceptualize information.
  • Second, it makes for greater ease of navigation thru the system.
  • Third, it's adapting a system in long usage that's not about to go out of business any time soon, so forcing it to better adapt to reality is a good thing.

• Now, the classification of the various unicellular organisms are certainly outside my area of core expertise, so I certainly welcome any good modifications to anything I've done. jaknouse 16:03 Apr 2, 2003 (UTC)

The Kingdom Protista was never anything more than a wastebasket taxon, and it's polyphyletic. Now that we as biologists are beginning to reveal the true (either monophyletic or paraphyletic) kingdoms of the organisms formerly considered members of the Kingdom Protista, the Kingdom Protista is now a discarded taxon.

As for logic and fixed categories, there are many more thresholds of genetic similarity than there are named ranks, but the use of named ranks makes taxonomy a lot easier to navigate than it would be otherwise, which is exactly why we use them. Based on how it makes things easier to wrap one's mind around, there are many such as myself who see no need for use of named ranks ever to cease, let alone "any time soon" as you put it. The Mysterious El Willstro (talk) 08:49, 6 February 2011 (UTC)

Browser formatting

I see the taxobox on the left margin overwritten by text. Is this a formatting problem or my browser? Skeetch

It looks like the div tags around tables break them on older browsers. Since the tables can be placed on the right without them, is there any reason not to get rid of them?

That fixed it for me. I'm using a current, MS-WIN2000 version of IE. Skeetch

Ok. It looks like the tags were added to create margins, but if they don't work on even newer browsers, they should definitely be removed in all cases. I will notify the author who had put them in.

Reverts

A quick note on some reverts. It was added that some eukaryotes - for instance diplomonads and microsporidia - do not have organelles. These groups are unusual in lacking mitochondria, but all eukaryotes have nuclei and an internal membrane system, and diplomonads have other organelles such as flagella. I also changed back the passage explicitly calling the protists a kingdom; not everyone classifies the eukaryotes that way, I don't think it makes things any more clear.

Also, someone changed the eukaryotes share a common origin to the eukaryotes are thought to share a common origin, and I've changed it back. There is no serious doubt on the matter, and we shouldn't treat all biology as a matter of opinion. Thanks, Josh

Surface to Volume ratio

Question: the reproduction part mentions that eukaryotes have a *smaller* volume to surface ratio than prokaryotes. It seems to me that since they can be a thousand times as big that they should have a *larger* volume to surface ratio, or, conversely, *smaller* surface to volume ratio? Cheers, Frank.

Mesomycetozoa

If you click on the link for Mesomycetozoa, it will say it is a class of Choanozoa. I think it should be replaced w/ Nucleariids. 74.185.212.232 (talk) 01:48, 24 April 2009 (UTC)

Pronunciation

how do you say it GrimRepr39 22:58, 6 September 2006 (UTC)

'You-carry-oat' Wikinterpreter

Archaea

The article needs to mention the modern three-domain system eukarya/archaea/bacteria very early on (say, in the second sentence). As it is, the article reads like the distinction between eukaryotes and prokaryotes is still thought of as the basic division of life; this view is obsolete. Archaea are more closely related to eukaryotes than to bacteria. In the article they are barely mentioned at all. --mglg_(talk) 23:39, 11 September 2006 (UTC)

well, i went and revised the intro. then saw your request, so i cleared up the fact that the three domains made up all of life, with link to domain biology. Wikiskimmer 02:16, 29 June 2007 (UTC)

Crista shapes

It's impossible to tell from the illustration whether the crista folds are shaped like condoms or toadstools (such as those that grow off the side of a tree). MaxEnt 15:50, 1 July 2007 (UTC)

if your question is serious, the answer is that mitochondrial crista have DIFFERENT shapes in different groups of eukaryotes.Wikiskimmer 18:44, 1 July 2007 (UTC)

Eukaroyte intro

he following is confusing: "Finally, reproduction involves a complex way of separating the duplicated chromosomes, called mitosis, which is also mediated by arrangements of microtubules."

When seeing "reproduction" I think of sexual reproduction, which is meiotic. I would clarify and expand using the concept of cell division such as

Eukaroytes utilized two types of cell division, each starting with DNA replication and separation of Chromosome pairs within a nucleus. In mitosis one diploid cell divides to produce two genetically identical cells. In meiosis, which is required in sexual reproduction, one diploid cell undergoes two stages of cell division, resulting in four haploid cells (gametes) each of which is genetically different. Kant58 19:15, 13 July 2007 (UTC)

Be bold! Bendž|Ť 20:05, 13 July 2007 (UTC)

that was my sentence, i merely wanted to succinctly describe the diff between euks and proks for the intro. to me that involves chromosomes and complex assemblies of microtubules. do you think it should be spelled out more in the intro or put in the body? ok, i tried it. Seems too complex now!Wikiskimmer 22:54, 13 July 2007 (UTC)

Cytoskeletal Structures

The description of the structure of microtubles is both confusing and misleading. "They are supported by a bundle of microtubules arising from a basal body, also called a kinetosome or centriole" This implies all three are the same and that Basal body is the superior term, which is contradicted first by the links for basal body, centriole & kinetosome, and the later sentences on centrioles. —Preceding unsigned comment added by 212.85.13.68 (talk) 09:33, 20 October 2007 (UTC)

Animal cells

An animal cell is a form of eukaryotic cell that makes up many tissues in animals.

Well, duh? Jack the Stripper (talk) 17:14, 19 November 2007 (UTC)

An update:

This is how the Eukariote tree looks like today (only four branches):

• Plants (red and green algae, including land plants)
• Unikonta (Animalia, Fungi and Amoebozoa)
• SAR (Stramenopiles+Alveolates+Rhizaria)
• Excavata (the remaining free living and parasitic organisms)

For the moment it is not possible to place Chromalveolate in any of these four groups, but it is most likely it belongs in the SAR-group, which will probably be confirmed in just a few years time (Kamran Shalchian and Kjetill S. Jakobsen).

Just wanted to mention it. 217.68.114.116 (talk) 09:53, 28 December 2007 (UTC)

The phylogeny proposed above appears in this paper:

Burki et al. 2007. Phylogenomics Reshuffles the Eukaryotic Supergroups. PLoS ONE 2(8): e790.

By the way, chromalveolates consist mostly of stramenopiles + alveolates, so they are a major part of the "SAR" group by definition.

While some agreement has emerged recently on the membership of eukaryotic supergroups, this paper shows that there is still much disagreement on how these groups are related to each other. We may be better off leaving contentious taxa like Cabozoa, Corticata, and Bikonta out of the taxoboxes until these are better resolved.

Cephal-odd (talk) 14:13, 16 January 2008 (UTC)

Hopefully there will be some answers in not too long. A few supergroups are better then a huge number of smaller groups. If Telonemia (in the Chromalveolata) belongs in the SAR group, then perhaps SAR and Unikonta are mest closely related, as Telonemia is said to remind a lot about basic animal cells. I also notice the list already mentioned does not include the glaucophyte algae, but i guess they belongs to the plant group anyway. 217.68.114.116 (talk) 13:54, 18 January 2008 (UTC)

My reading of the Burki et al paper is that there is a lot about this stuff which isn't certain yet. If you aren't sure of the monophyly of, say, the Chromalveolata (or one of the subgroups within it, or whatever), it is hard to sample enough different species to make sure that your cladogram really makes any sense. I agree with Cephal-odd that Cabozoa and Corticata are to be treated as hypotheses (and perhaps not even the favored ones) rather than as established. I'm not sure about Bikonta; at least as far as I could tell from the Burki et al paper their data seems to support bikont versus unikont distinctions. As for glaucophytes, yes those are part of Archaeplastida (at least according to our articles). Kingdon (talk) 20:35, 23 January 2008 (UTC)

Eukaryotes and the evolution of sex

Bernt Walther has proposed that the origin of eukaryotes occured at the same time as the origin of sex. Is this something we should mention in the article?--Gunnar Mikalsen Kvifte (talk) 22:25, 3 February 2008 (UTC)

I would think that Evolution of sex would be the place for any discussion of this. It is hardly an area I know much about, but I see a lot of speculation and not so much well-established fact, which might make it difficult for us to say much about it. Kingdon (talk) 03:22, 4 February 2008 (UTC)

Fossil record

A few months ago, the start of the fossil_range parameter was changed from Proterozoic to Mesoproterozoic. It's true that the Mesoproterozoic saw a big increase in eukaryote like fossils, including Bangiomorpha, the first fossil to fit into a modern group (red algae in this case). But there is some evidence of eukaryotes going back before 1600 million years ago, into the Paleoproterozoic, including acritarchs and the possible alga Grypania. Because these claims are not without controversy, I think it best to leave the starting time as Proterozoic, and have made it so in the taxobox. Cephal-odd (talk) 05:34, 18 May 2008 (UTC)

Fossil_range is for the fossil record only. We don't have a field for molecular divergence yet, but we're discussing at at WP:TOL. Perhaps you'd like to share some input there. Now the big question...you just said that the oldest fossil is from Mesoproterozoic, but in the article you indicate quite clearly the Paleoproterozoic...which one is actually the oldest fossil? Bob the Wikipedian (talk) 20:56, 18 May 2008 (UTC)

Agreed about the fossil_range value. So far I haven't even attempted to address the molecular clock estimates of divergence times between eukaryotes and whatever prokaryotes they're most closely related to. Such an estimate would probably have a huge margin of error. The Knoll et al. paper cited in the article clearly argues for the presence of Eukaryote body fossils going back to the Paleoproterozoic. The Mesoproterozoic just has a lot more such fossils, including ones that have convinced almost everyone that eukaryotes were around then. Also, the oldest fossil that can be assigned to a specific modern group of eukaryotes is Bangiomorpha from the Proterozoic.

Biomarkers are another issue again. These are quite different from molecular clock estimates of divergent times; they are chemical traces that are thought to be left by a particular kind of organism -- in this case, steranes from eukaryotes dating to 2700 Ma. These biomarkers are not usually considered fossils, but with a little stretching they could be considered trace fossils, since they are an observable remnant of the organisms' activity, in contrast with a theoretical divergence date. Cheers, Cephal-odd (talk) 22:45, 18 May 2008 (UTC)

You've inspired me to go look up the word "sterane". :) Bob the Wikipedian (talk) 12:24, 19 May 2008 (UTC)

9+2 arrangement

Eukaryotes often have unique flagella made of microtubules in a 9+2 arrangement

The phrase "9+2 arrangement" should either have an explanation or have a link (to a new brief article describing the 9+2 structure) or be dropped.Originalname37 (talk) 15:06, 11 August 2008 (UTC)

There is an explanation at Flagellum#Structure that can be incorporated here, but I'd drop it, or at least move it down from the lede. Narayanese (talk) 17:36, 11 August 2008 (UTC)

I got rid of the whole sentence. It's all in the "Cytoskeletal structures" section. Flagella are not central enough to the subject to be in the lede.Originalname37 (talk) 04:14, 12 August 2008 (UTC)

Authority

This article states that the taxon authority of the domain Eukaryota is "Whittaker & Margulis,1978". However, it is very common to see "Chatton 1925" instead of it. Why is it so?--212.20.74.230 (talk) 14:01, 7 September 2008 (UTC)

Neomura

Does Neomura really belong in the taxobox? It seems like (a) an unresolved area of research, and (b) even if it were well-established, wouldn't belong in the taxobox (after all, there are only three domains). It is better to cover this in the text with suitable caveats, and as far as I can tell the text starting with "some place them with Archaea in the clade Neomura. In other respects, such as membrane composition, they are similar to eubacteria" does a good job of it. So I'd propose to simply get rid of the unranked_superdomain line in the taxobox and delete the sentence "But eukaryotes do share some aspects of their biochemistry with archaea, and so are grouped with archaea in the clade Neomura." from the lead. Comments? Kingdon (talk) 23:14, 18 February 2009 (UTC)

I agree. We follow the mainstream, and the mainstream view is Bacteria, Archaea and Eukaryota. Alternative hypotheses that have not become widely-accepted belong as brief mentions in the text. Tim Vickers (talk) 23:19, 18 February 2009 (UTC)

I have made this change. Kingdon (talk) 15:36, 23 February 2009 (UTC)

It seems that Neomura had crept into the taxobox again, and someone hid it yesterday. I think that for now it should stay hidden or deleted. -- Donald Albury 10:59, 10 June 2011 (UTC)

Fungi most similar to animals?

The article currently states: "Fungal cells are most similar to animal cells, with the following exceptions:" It seems to me as though they are actually more similar to plant cells - having a cell wall, vacuole, septa (~ to plasmodesmata) and being multinucleated. Should this be changed? Smartse (talk) 16:42, 13 April 2009 (UTC)

The cell wall is different in composition (cellulose in plants; chitin in fungi). As for multinucleated, if this occurs in plants, perhaps Multinucleate should be updated. Right now it mentions fungi, certain animal cells, and Proteus mirabilis swarmer cells (which I don't understand, as P. mirabilis is a bacterium and I'm not sure what a swarmer cell is). While I can see the resemblence between plasmodesmata and the septa (discussed at Hypha) of fungi, there is just as close an analogy to membrane nanotubes of animals. Vacuole similarities are perhaps the strongest case, although vacuoles exist in many groups and I assume the similarity is one of similar use rather than similar details (although I don't really know). Perhaps it is easiest to just discuss the structure of fungal cells without an explicit "like X except" statement; the list of traits wouldn't really be much longer than the list of exceptions the way things are arranged now. Kingdon (talk) 00:51, 14 April 2009 (UTC)

I agree - I think it would be best to describe fungal cells without any "like X except" statement. If this is the case the first sentence about plant cells needs to be changed as well. Should we do this? The vacuoles in plants and fungi serve similar functions (maintaining turgor, storage, cell expansion) but in other groups are effectively a dustbin. I've been trying to update vacuole too - help would be appreciated. Some plant cells can be multinucleate - the article has been changed accordingly. Thanks Smartse (talk) 18:48, 14 April 2009 (UTC)

what is the importance of the eukaryote cell —Preceding unsigned comment added by 140.198.73.103 (talk) 03:20, 14 April 2009 (UTC)

Fungi are most similar to aminalia cells.--Dannymilliren (talk) 22:43, 1 October 2011 (UTC)

"Most living organisms"

Most living organisms, including all animals, plants, fungi, and protists, are eukaryotes.

Is this true? Much of the world's biomass consists of prokaryotes, and according to the bacteria article "there are approximately five nonillion (5×10^30) bacteria on Earth". Surely that's much more than the number of eukaryotes?

--84.215.143.128 (talk) 10:57, 21 July 2009 (UTC)

Good question - although when I read that I think of species rather than the absolute number of distinct organisms. I think that this is the point that is trying be got across as this (almost certainly) is the case. It could be changed to make it more clear. Smartse (talk) 15:35, 21 July 2009 (UTC)

Yes, that is almost certainly wrong. Most species and most cells are prokaryotes. Tim Vickers (talk) 15:49, 21 July 2009 (UTC)

Well we don't really have any clue how many prokaryotes there are do we? There are many millions of species of insects and plants however. Smartse (talk) 15:53, 21 July 2009 (UTC)

That is discussed in the bacteria article, as I remember the estimates range over several order of magnitude. I've reworded this article to state "Almost all species of large organisms are eukaryotes, including animals, plants and fungi, although most species of eukaryotic protists are microorganisms." The exceptions are a few species of bacteria that are just visible to the naked eye. Tim Vickers (talk) 15:56, 21 July 2009 (UTC)

PMID 12097644 and PMID 15590780 discuss bacterial species number. Tim Vickers (talk) 15:59, 21 July 2009 (UTC)

Hey

i think you should explane every think some what better so if a liitle kide wants to know what this stuff is then they can read and find out what this stuff is... just saying.. —Preceding unsigned comment added by 167.128.163.24 (talk) 16:41, 13 November 2009 (UTC)

What don't you understand? Smartse (talk) 16:52, 13 November 2009 (UTC)

Read Darklife by Michael Ray Taylor if you need it explained in such a mannor. —Preceding unsigned comment added by 220.244.47.107 (talk) 15:21, 6 January 2010 (UTC)

Fill in the Blank Cell Diagrams

I do not know where these may be most helpful. I personally found myself coming to wikipedia in search of a good fill in the blank diagram of cells. I could not find one on the internet (of good resolution), so I decided to draw and scan my own. I propose inclusion as an external link at the bottom of the article. I already released the image freely for personal and educational use.

Generic fill in the blank animal cell picture. [1] Generic fill in the blank plant cell picture. [2]

I know they are large. I created them and kept them at high resolution to provide a clear print out for practice as a biology student. If this would be better used elsewhere on wikipedia, I'm open to at too. I want to help people learn about a subject I enjoy, and put forth time and effort to do so.

Liberum Vir (talk) 07:44, 7 February 2010 (UTC)

Thanks for the links but we already have blank copies the animal and plant cell diagrams that you could have used: File:Plant cell structure no text.png and File:Anima cell notext.svg. Smartse (talk) 12:36, 7 February 2010 (UTC)

Expansion of "Six supergroup model and two clade model" section

I've expanded (and hopefully clarified) this section. I'm not sure whether the detail in the two cladograms should be included or not. I did so because (a) they explain how the old 6 supergroups get split up in more modern approaches (b) they illustrate the unikont/bikont split (c) their differences make clear the uncertainties which exist at present. On the other hand, perhaps their inclusion gives undue weight to the two papers on which they are based compared to other possible cladograms in the literature. Any views? Peter coxhead (talk) 22:02, 26 April 2010 (UTC)

Kingdoms, Kingdoms Not

Cavalier-Smith (2004) Only six kingdoms of life determined that there are only 6 kingdoms of life: one, Bacteria, in the Empire (Domain) Prokaryota. and five, Protozoa, Anamalia, Fungi, Plantae, and Chromista in the Eurkaryota; for which the list in the taxobox is partly in conflict.

Three of the taxa listed, Amimlia, Fungi, and Plantae are generally recongnized as kingdoms, as might be Chromaveola if synonymous with Chromista. On the other hand, according to Cavalier-Smith, Ameobozoa, Rhizaria and Excavata are not. Rhizaria and Excavata are infrakingdoms and Ameobozoa is a phylum in the subkingdom Sarcomastigota; all within the Kingdom Protozoa. No other taxonomy as I recall seriously conflicts with this overall perspective.

Ameobozoa, Rhizaria and Excavata should be discontinued as kingdoms; they could actually fit well at the phylum level. Infrakingdom does not a kindom make any more than does suborder make something an order or subfamily make it a family.

In conclusion, the kingdoms should be listed as Protozoa, Animalia, Fungi, Plantae, and Chromista. J.H.McDonnell (talk) 01:31, 26 June 2010 (UTC)

That's 2004. More recent literature reveals the 3-Domain system, where the Domain Eukarya alone has more than 6 kingdoms. See the sources already cited by the Article that are newer than 2004. The Mysterious El Willstro (talk) 07:01, 11 July 2010 (UTC)

There are two different issues here: (1) the 'philosophy' of biological classification and (2) the status of research into the evolution of the eukaryotes.

• Cavalier-Smith does not accept the need for Kingdoms to be monophyletic, that is to include an ancestor and all of its descendants. There's no right or wrong answer to whether Kingdoms should be monophyletic or not; there are valid arguments either way. The current fashion, and hence the current consensus, appears to be that formal taxa should be monophyletic so that Cavalier-Smith's kingdoms are out of fashion and hence not at present likely to be the basis of a consensus. The specific problem is his Kingdom Protozoa, which contains the ancestors of Animalia, Fungi, Plantae and Chromista. (There's a diagram showing this in this paper [3], but unfortunately it's not public access.) Personally, I really like Cavalier-Smith's classification, but this is irrelevant; as a Wikipedia editor I have to look for a consensus and at present I conclude it's against him.
• At one time Cavalier-Smith's Chromista was significantly different from the Chromalveolata of other workers in the field. However, this paper [4] (which is public access) shows that he is now in line with others in this respect (and it's Cavalier-Smith who has changed, not Burki et al.). However, there is still a big difference. Cavalier-Smith does not accept that the Archaea-Eubacteria division is fundamental. My reading of the literature is that the majority of workers do not agree with him and that this is supported by evidence (see e.g. this recent paper [5].)

So although the Cavalier-Smith model has its merits, it can't be regarded as currently acceptable as a consensus classification. There just isn't one, although research does seem to be moving in that direction. If there were an accepted consensus at present it would probably be to divide cellular life into two prokaryote Kingdoms, Archaea and (Eu)Bacteria, and five eukaryote Kingdoms, Excavata, Amoebozoa, Opisthokonta, Chromalveolata and Archaeplastida (=Plantae s.l.). But the reality is that the evidence isn't all in yet (e.g. where do the Apusozoa fit?) and there isn't a consensus that I can discover, however annoying this is. Peter coxhead (talk) 22:54, 3 December 2010 (UTC)

All large complex organisms are eukaryotes

Are there any large purely non-eukaryote organisms that aren't non-differentiated colonies? Hcobb (talk) 04:42, 26 October 2010 (UTC)

This isn't related to improving the article, as far as I can tell. You'd probably be better off asking at the science reference desk. Smartse (talk) 10:05, 26 October 2010 (UTC)

Yes, Hcobb, all multicellular organisms are members of the Domain Eukarya. However, the Domain Eukarya does include several single-celled kingdoms (Kingdom Excavata, for example). The Mysterious El Willstro (talk) 08:37, 6 February 2011 (UTC)

Spelling correction

According to Prescott's Microbiology, the domain name is correctly spelled Eukarya, not Eukaryota (note how the "ot" is extra) as the Article currently has it in the InfoBox. Here is my source:

Prescott's Microbiology, by Joanne M. Willey, Linda M. Sherwood, and Christopher J. Woolverton, 8th Edition. Copyright date: 2011. Publisher: McGraw Hill.

Yes, it's a textbook, but it's a 300-level textbook as opposed to a 100-level or high school textbook. Besides, it's a lot more recent than Whittaker and Margulis (1978).

Not only is my source quite reliable, but the simpler spelling is also more aesthetically pleasing and more consistent with the other 2 domains (IE Bacteria, not Bacteriota; and Archaea, not Archaeota). So, can we please make this change in the InfoBox? The Mysterious El Willstro (talk) 22:05, 5 February 2012 (UTC)

The lede indicates that both Eukarya and Eukaryota are in formal use. A quick Google search also shows both forms in widespread use. Which form to use in the taxobox should not be decided by a single source, no matter how reliable, if other reliable sources use a different form. As for consistency in naming, we have singular bacterium, plural bacteria, domain Bacteria; singular archaeon, plural archaea or archaeans, domain Archaea; and singular eukaryote, plural eukaryotes, domain Eukaryota or Eukarya. Taxonomy is sometimes messy. -- Donald Albury 01:22, 6 February 2012 (UTC)

If they are both used, but this one is referenced in a recent, respected tertiary text, it seems like using Eukarya in the taxobox is appropriate, even preferred to a much older source in a subject where our knowledge of phylogenetic relationships has changed so dramatically due to advances in technology after 1978. 03:07, 6 February 2012 (UTC)

My point is that we need to look at which, if either, form is more prevalent in recent reliable sources. Both forms are in use on web sites that I would consider reliable. I don't have easy access to recent books and scientific articles to judge which form is more prevalent in print. I don't think the change should be made on the basis of one book. It does look like something to be settled by consensus on this talk page. -- Donald Albury 12:37, 6 February 2012 (UTC)

I consider making a change on the basis of a current, reliable, tertiary resource to be preferable to keeping an old statement. After the change, if editors have time to research multiple sources a decision about which is preferable can be made. But, currently, it's based on a source that does not have modern era molecular phylogenetics evidence. It's like referencing D. melanogaster on Woodworth where modern texts say something different until you find agreement among modern texts. This is a highly accessed article, and it's irresponsible to base taxonomic names on on data pre-computation, pre-molecular genetics. After changing it, a literature search can be done and arguments made for a preference one way or the other. But without a modern reference (not a google search) for the other choice, the referenced choice is preferable to potentially out-of-date science. You could check a modern Margulis reference. Pseudofusulina (talk) 16:25, 6 February 2012 (UTC)