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Can someone please give me some tips or help me build a cladogram from the following table of information? The outgroup is Lancelets and the first derived character is vertebrae, followed by Lampreys and jaws I believe. It’s not until after jaws I have trouble figuring out where to link up the organisms and traits. I’m assuming you cannot repeat or remove traits. When I look online the simpler examples do not help me much for this branching issue...I hope that made sense. It’s probably simpler then I think but I’m having a mental block with it. Any help would be great, thanks

  • $\begingroup$ Hi and welcome to this site. There are dozens of "How to draw a cladogram" instructions on the internet. Could be please edit your question and add, how you would follow those instructions with your example, and at what step exactly you are struggling? This community expects you to show you own efforts, otherwise your question might be closed as homework(like) question. $\endgroup$ – Arsak Mar 21 '18 at 19:56
  • $\begingroup$ I have looked online at written explanations and videos. I get the concept but for some reason I can only get so far with it until it just doesn’t make sense where to place the organisms in relation to the derived and shared characteristics. Most online examples seem to be a bit simpler with less variables. $\endgroup$ – Maria Mar 21 '18 at 20:29
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    $\begingroup$ @Maria When the data size increases, one usually uses a computer program to build the tree, because it gets impossible to manually explore all the tree topologies and see which one is most parsimonious. $\endgroup$ – bli Mar 23 '18 at 14:45

I think the clue is at each step to look for the trait that is shared by most of the remaining taxa.

In your example: 9 out of 10 taxa are vertebrae. So you are correct to pick this trait first and outgroup Lancelets.

Looking at the remaining 9 taxa: 8 have jaws, and a different set of 8 swim bladders or lungs At this point you can pick one of those traits, as far as I know. You chose jaws and outgrouped Lampreys.

In the remaining 8 taxa, the characteristic that is shared by most of them (7), is having swim bladders or lungs. Thus, you can outgroup Sharks here.

In that way, you can go on for the remaining traits and taxa.

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    $\begingroup$ Please leave a a comment on how to improve the answer if you think it deserves a down vote. $\endgroup$ – Arsak Mar 21 '18 at 22:28

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