Talk:Cladogram

Not a cladogram!

The first figure of the article, the unrooted myosin supergene family tree, is NOT a cladogram. It's distance-matrix tree! (check the abstract of the original paper). I'm removing it.

I suggest replacing it with the second figure of this paper, the famous 1999 dinosaur phylogeny of Paul Sereno, which is nicely illustrated. I think it should qualify as fair use. --Earrnz (talk) 03:03, 7 January 2010 (UTC)

simple cladistics diagram

Isn't there a bug on the second diagram? Traits B,C are shown on the line pointing to species 3 which only has trait A, it should be on the line pointing to species 1 surely? --86.179.186.239 (talk) 12:44, 23 March 2010 (UTC)

You're right, anonymous, thanks for pointing it out. I will correct it ASAP.--Earrnz (talk) 03:32, 18 April 2010 (UTC)

How to read a cladistics diagram

The article contains a section on what a cladistics diagram is, and a section on how to generate one. What's missing is an intermediate section on how to read one.Christopher King (talk) 14:58, 28 October 2010 (UTC)

This article incorrectly defines a cladogram. There is no consensus about the exact meaning of the term, and the second sentence contradicts itself. The nodes are the ancestors and quite clearly indicate the relationships between the terminals and the nodes, and even other nodes.See:

http://www.ucmp.berkeley.edu/clad/clad3.htm

http://www.bu.edu/gk12/eric/cladogram.pdf

http://www.brooklyn.cuny.edu/bc/ahp/CLAS/CLAS.Clad.html

There are a bunch of others, but I think this proves the point. 66.168.116.107 (talk) 16:50, 15 June 2014 (UTC)

You are right that the term is used to cover two kinds of diagram. One, the most common, is when the terminals are known taxa, extant or extinct, and the branches show the hypothesised evolutionary relationships between them. The nodes can then be interpreted as hypothetical ancestors. Note that in the Hennigian approach, if a node is given the characters inferred from a cladogram and the construction process repeated, it will become a terminal. That's what I mean by the nodes being "hypothetical" ancestors. This appears to be the usage intended by the last two links you put above (the first doesn't seem to work). The second kind of diagram is when the nodes are also known taxa and some method other than cladistics is used to construct the diagram – such diagrams are sometimes called phylograms. Unfortunately many sources are not clear on these differences.

I don't think the second sentence is as clear as it could be, but it's not contradictory: a cladogram in the original Hennigian sense is not a full evolutionary tree: the arc lengths have no meaning, and the nodes are not known ancestral taxa. All it shows is the inferred branching order. Some thought is needed as to how the second sentence can be improved. Peter coxhead (talk) 00:27, 16 June 2014 (UTC)

Dear Author, I copied three sentences off of your article on Cladograms on Wikipedia. For that I deeply I apologize.I had used it for a question on one of my school tests because it had asked what a Cladogram was and I had no idea what it was so I had looked it up and I had copied it.I am really sorry. And I realize how bad what is I did. I will never do it again.I apologize for what I have done. And I feel really bad because of my actions.I aknowledge that I have plagarized and I am so very sorry. — Preceding unsigned comment added by 74.78.86.101 (talk) 00:56, 3 December 2014 (UTC)

What is and is not a cladogram

The following section was recently added; I have removed it pending further discussion.

What is a cladogram and what is not a cladogram?

As noted above, a cladogram is the diagrammatic result of a parsimony analysis, which groups taxa on the basis of synapomorphies alone. There are many other phylogenetic algorithms that treat data somewhat differently, and result in phylogenetic trees that look like cladograms but are not cladograms. For example, phenetic algorithms, such as UPGMA and Neighbor-Joining, group by overall similarity, and treat both synapomorphies and symplesiomorphies as evidence of grouping, The resulting diagrams are phenograms, not cladograms, Similarly, the results of model-based methods (Maximum Likelihood or Bayesian approaches) that take into account both branching order and "branch length," count both synapomorphies and autapomorphies as evidence for or against grouping, The diagrams resulting from those sorts of analysis are not cladograms, either.

Without sourcing, this is just a matter of opinion as to how terms should be used. Some authors restrict the term "cladogram" to phylogenetic trees produced in strict accordance with Hennigian principles, but the term is, in my experience of the literature, used much more loosely now. By all means discuss alternative usages of the term "cladogram" but the material must be attributed to a reliable source.

As an example of "loose" usage, The Kew Plant Glossary, published by the Royal Botanic Gardens, Kew, no less, gives the definition:

cladogram, in cladistics, 2-dimensional tree diagram showing relationships between taxa that are based on shared character states

This applies equally well to counting symplesiomorphies as synapomorphies, and says nothing about how the tree was constructed. Peter coxhead (talk) 18:40, 30 July 2015 (UTC)

Note that the Kew definition starts with "in cladistics". That would seem to restrict the domain of that definition of the word to the cladistic method, which (one hopes, at least) implies grouping by synapomorphy. One sloppy definition is not an excuse for another. It seems to me that the point of an encyclopedia is to provide precise definitions of terms - alternative ones, if necessary. For example, what is a "Yankee"? An American? A northerner? A baseball player? Vagueness leads to confusion or deliberate obfuscation. Abrower (talk) 12:42, 5 August 2015 (UTC)