Talk:Clade

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Yes this still needs work. Key issues are:

• What should usefully be here? As opposed to just referring to cladistics
• What is the exact definition of a clade? As opposed to how the word is used commonly. And how should this exact definition relate to this entry?

It bears thinking on, exact definitions are not easily written (and even less easily accepted). Brya 09:01, 18 February 2006 (UTC)

Oh, dear. I'm afraid I agree with Elijahmeeks. I'm not a *complete* idiot, but I barely understood a word of this article. Which is too bad - this is a very interesting topic. Perhaps some expert/editor could try this: imagine you're talking with a bright high school student -- start with the basics, without jargon, then move up to exacting terminology you require to be precise. JamestownArarat 01:27, 5 October 2007 (UTC)

[edit] Monophyly, paraphyly and polyphyly

(Moved from talk:phylogenetics)

These should all be merged into one article, probably this one. I don't think they have the potential to stand on their own, and this article needs more detail anyway. Richard001 08:36, 4 May 2007 (UTC)

As long as there is a stub that links people to the article on phylogeny, this would be fine. There should definitely be discussion of these topics on the phylogeny page.

Yeah, merge it since monophyly paraphyly and other methods of organization are organized as a parts of phylogenetics in most scientific literature.Wiki wiki1 01:02, 19 June 2007 (UTC)

Apparently paraphyly is also known as an 'evolutionary grade. We need a place which mentions such concept which is useful when talking about the now-discredited progressive evolution. See the 'Sauropsids' section (just search for it) in the article The Ancestor's Tale. Fred Hsu 03:15, 10 August 2007 (UTC)

Agree, I can't see these articles growing to be much more than dictionary definitions once repetitions are done away with. Bendž|Ť 19:02, 1 September 2007 (UTC)

I had a look to see if the word 'phyly' was used as a stand-alone term to describe the three forms, but I've only see it used once. Compare with say ploidy, which is used commonly. We could either move them all the somewhat contrived phyly, or merge them here - which is best? Richard001 07:53, 10 September 2007 (UTC)

I've moved the target page to clade, as a monophyletic group and a clade are the same thing. This is probably the best article to redirect them to. Richard001 06:57, 4 November 2007 (UTC)

Agree. These three terms are very critical, but individual articles become simply dictionary entries. They key is realizing that any discussion of _one_ of the terms requires comparison with the other two terms. Thus, they should all be in one article. The real question is: what article? The only two candidates are Clade and Cladistics. Cladistics is obviously the "main" go-to article for the topic. But the "Clade" article is more specific, and its thrust is defining a certain kind of organism-grouping. Which is what these three articles are doing. Hence, these three articles would naturally fit into the Clade article. So I think it would be okay to merge these three articles into Clade.

Noleander 21:53, 6 November 2007 (UTC)

Disagree. None of these four articles are dictionary definitions. Hundreds of articles link to these articles, so whatever decision is made should not be taken lightly, and should be brought to the attention of WP:TOL and the various animal and plant WikiProjects which link to these articles. Also, -phyly is a suffix, not a word. Firsfron of Ronchester 09:57, 12 November 2007 (UTC)

Disagree. There's more than enough information on each separate terms to keep them as different pages, though I do agree all the articles need to be fleshed out quite a bit. I'd help but I haven't had much free time as of recent. --Kugamazog 01:48, 2 December 2007 (UTC)

Disagree. Giving these their own space makes it much more likely that editors will work up the best means for easily getting across the important distinctions right away, and there's plenty further to go into from there. Many folks still have a lot of "common sense" learning in this area, which would be much more readily updated with separate articles that folks manage to elegantly or at least clearly and plainly present these critical points of understanding. Linguistics articles here can often be the opposite of what I mean, but browsing about animals is likely a less esoteric exploration; the potential to illuminate things for curious folks coming by via popular articles is pretty great. --chaizzilla (talk) 17:42, 25 May 2008 (UTC)

AndrewBolt (talk) 08:56, 5 May 2008 (UTC) I was redirected to the Clade page by a link to Monophyletic. The summary for the page says that a clade is a monophyletic group. This is not very helpful since that is the very term I'm trying to understand. There is enough information in the article body to figure it out, but it would be if the summary didn't give an explanation in terms of the words that redirect to the page.

I have recently explained (Envall: Biol J Linn Soc, 94:217-220) that the term "clade" rests on a confusion of process and pattern, and that it therefore is inconsistent. It actually refers to both mono-, holo- and paraphyletic groups, although those that are confused (i.e., cladists) "deny" paraphyletic groups. The truthfulness of this statement is easily verified by using "clade" on paraphyletic groups; there is nothing that excludes them from the concept. The reason cladists deny paraphyletic groups is that they confuse kinds of things in a row, whereas paraphyletic groups are kinds of things alongside (and mixtures of kinds of things in a row and alongside). Their confusion thus forces them to deny the fact that also paraphyletic groups are clades. Without their confusion, clades are simply monophyletic groups, and monophyletic groups are holo- and paraphyletic groups (whereof the former is pattern and the latter are processes). Their confusion (i.e., cladism) is just as difficult to understand as the correct comprehension of phylogenies (i.e., dichotomously branching processes) is. —Preceding unsigned comment added by 83.254.23.159 (talk) 22:17, 23 June 2008 (UTC)

Cladism is actually an unholy (i.e., hypocritical) confusion of the incompatible comprehensions held by Parmenides and Heracleitos about 2,400 years ago, which were consistently synthesized by Aristotle about 2,300 years ago (which, by the way, also laid the foundation for science in general as well as Linné's consistent and correct conceptualization of phylogenies). Cladism is thus a new attempt to handle the essential difference between process and pattern: hypocriticism (or applied inconsistency) instead of consistency. Mats Envall. —Preceding unsigned comment added by 83.254.23.159 (talk) 22:33, 23 June 2008 (UTC)

The definition of 'clade' as "and ancestor and all its descendants" is ambiguous. Representing a phylogeny including only one splitting means that it represents one ancestor and two descendants. Representing two consecutive splittings, however, means that it represents one ancestor in the beginning, three descendants in the end, and one thing (i.e., line segment) in the middle that is ambiguous between being an ancestor and a descendant. If this ambiguity applies to all line segments in the representation, then all single things are clades, meaning that all groups of adjoining things also are clades. If not, then this ambiguity has to represent two things in a row. The definition of 'clade' thus has two meanings depending on how the ambiguity of the middle line segment is interpreted, and Hennig's interpretation actually denies his denial of paraphyletic groups. His interpretation actually includes paraphyletic groups in his definition of clades. I would analogize his attempts to get rid of paraphyletic groups with trying to get rid of snot from his forefinger by sticking it in his nose. Mats Envall. —Preceding unsigned comment added by 83.254.23.159 (talk) 23:25, 23 June 2008 (UTC)

A partitioning of a single asymmetrical phylogeny into clades is ambiguous per definition, since things and their properties actually are both congruent and incongruent. This is shown by the fact that there are three different possibilities to define clades (i.e., stem-, apomorphy- and node-based definitions). The ambiguity means that the stem- and node-based definitions are incompatible with each other, whereas the apomorphy-based definition is incompatible with both the stem- and node-based definitions, and that each of them by themselves depends on the partitioning of properties into characters and character states, which, in turn, contains several equally correct possibilities, since properties are both congruent and incongruent. Stem- and node-based definitions only acknowledge incongruence between properties, whereas apomorphy-based definitions only acknowledges congruence between properties. The empirically correct choice between these is congruence (i.e., apomorphy-based definitions), since simultaneity (concurrency) is an undeniable fact (and a truth per definition). Stem- and node-based definitions are instead mutually contradictory and empirically wrong. The correct choice (congruence and thus apomorphy-based definitions) actually composes the foundation for the consistent and correct Linnean classification. The reason that this system does not differentiate between apo- and plesiomorphic properties is that this distinction includes the incongruence between properties which has to be discarded to avoid falling into the ambiguity (i.e., confusion) explained above, which may lead to the erroneous choice explained above. We simply have to choose between acknowledging congruence or incongruence between properties to avoid falling into a total conceptual confusion, and the empirically correct choice is congruence. This choice means that 'clades' equals mono-, holo- and paraphyletic groups (the former pattern and the latter two processes) as I explained above. Mats Envall —Preceding unsigned comment added by 83.254.23.159 (talk) 08:10, 24 June 2008 (UTC)

[edit] Monophyletic groups vs clades

Why am I redirected to clades when I search for the definition of monophyletic groups? Clades are not, I repeat not, equal to monophyletic groups. Clades is a actually a conceptual confusion of the specific holophyletic groups with its generic monophyletic groups excluding the other specific paraphyletic groups. Both holo- and paraphyletic groups are thus monophyletic groups. It means that clades cannot possibly equal monophyletic groups. Are the editors confused?Consist (talk) 22:38, 12 July 2008 (UTC)

I can also add that there is no article on paraphyletic groups in Wikipedia. As far as I understand, there are mono and polyphyletic groups. If someone wants to partition monophyletic groups into holo- and paraphyletic groups, confusing holo- with monophyletic groups, he should at least provide a definition of paraphyletic groups. We can only define things we see, and has anyone seen a clade or a paraphyletic group? Has biological systematics gone mad? Consist (talk) 22:48, 12 July 2008 (UTC)

"Paraphyletic groups" emerge if one thinks that a decendant equals its ancestor, because there are two descendants in each splitting in dichotomously branching processes. When the phylogeny is asymmetrical, this erroneous assumption leaves paraphyletic groups. 83.254.23.159 (talk) 23:08, 12 July 2008 (UTC)

Clarification. Clades as well as taxa, which are not exactly the same thing are monophyletc. That is they have a single common ancestor, are derived from a single stock. While valid clades and valid taxa are monophyletec, the term monophyletic is an adjective that describes the noun.

Paraphyletic groups are another matter. They have to do with exclusivity, not with ancestry. Paraphyletic groups or taxa include some, but not all the descendants of their common ancestor as in the Synapsida, taxonomically speaking excluding the Mammalia. The principle of paraphyly which should not be that difficult to comprehend keeps taxa reasonably concise and from becoming too diverse. John McD7/26/2008

[edit] Clades, Cladistics, etc.

There seems to be some confustion over clades and cladistics and over terms like paraphyly and polyphyly. A clade is a group of organisms stemming from a common ancestor. Diagrammatically a clade is depicted as a branch or group of branches originating at some point called a node. Since there can be ancestors before the branching point the common ancestor originating the particular clade is referred to as the "most recent common ancestor". A clade should probably not be thought of as a taxon in the ordinary (Lennaean) sense, but rather as an evolutionary continuum beginning at some selected point.

Cladistics is simply the use and analysis of clades in determining and depicting evolutionary relationships among organisms (plants, animals, etc). living or fossil.

There are two problems with pure cladistics which have to do with separability and diminishing returns. Clades cannot be separated from parent clades and derived clades become inferentially smaller and smaller. A branch on a real tree can not attain the same or greater weight as the branch from wence ti came. Nor can a clade or evolutionary branch take on a taxonomic weight equal or greater than that of the branch from wence it came. Cladistics attemps to reconcile this dilemma by eliminating taxa or by borrowing from traditional (Lennaean) taxonomy.

Cladistics is a perfectly good and valid approach to the study of organisms. But it is not the only or necessarily best approach at all times. Traditional taxonomy is not nearly as wrought with problems as some allege and often gives a better picture.

John McD7/26/2008