Lab #5: Trilobit Phylogenetic Tree by Darsi Fouillade, Hiu Nam (Tiger) Wong, Travis Friesner, Solace Asong
Group Member Names: Darsi Fouillade, Hiu Nam (Tiger) Wong, Travis Friesner and Solace Asong
Date of Lab: 1/16/18
Figure 1. Picture of the phylogenetic tree generated by our group.
Figure 2. Key for the phylogenetic tree.
The outgroup was species number 3, Peronopsis interstricta. This group did not have the focused traits and looked significantly different from the other species. For example, we were not able to identify the head/tail side of the individual, and this species do not have the long thorax section like other samples. Due to the significant difference of its appearance with other species, we selected Peronopsis interstricta as the outgroup.
2. According to your tree, what is one basal or ancestral characteristic? One derived characteristic?
One basal characteristic was a squarish and non-irregular glabella. One derived characteristic was the presence of a genal spine.
3. According to your tree, is the rear ‘spine’ of species 6 homologous or analogous (homoplastic) to that of species 14? Explain.
I’m going to gander it is homoplastic, because in 6 the tail is part of the axial lobe, while in 14 it is part of the pleural lobe.
According to our tree, the rear spine of species 6 is homologous to that of species 14, as we have categorized both species under the clade that are single tailed.
4. Are there any traits that were lost but then evolved again independently? ________
If so, what are they and where do they occur?
According to the tree we constructed, the are no traits that were lost but evolved again. However, we do find convergent traits in species 7, 13, 19, where they all have long genal spine but they are classified in different clade, and species 1, 16, 10, which they all have short genal spine but are categorized in different clade.
5. Describe one important difference between your tree and a tree estimated by a different lab group (identify which group’s tree you used). Upon reflection, which tree seems better? 
Figure 3. Picture of phylogenetic tree constructed by Mackenzie’s group within same lab section.
Earlier on in the tree, our group used the presence of genal spine to categorized the individuals into two larger monophyletic group, while the other group used the presence of occipital ring to divide the sample into two larger clades. One other major difference in our tree show the species exist in one period while the other group’s tree displays species existing in different periods and suggest different points of extinction. The phylogenetic tree constructed by the other group is more detailed and suggests the time of when each species is formed, which provides a more informative phylogenetic tree than ours.
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ReplyDeleteYou guys structured your tree pretty much the exact opposite of what my group did! The outgroup is the same, but we put species number 10 as one of the more evolved organisms, and the organisms that had longer bodies were closer to the ancestor. We thought spots/texture would be more favorable (for what reason I'm kind of blanking on) and I'm wondering why you guys have that trait earlier in your tree?
DeleteAwesome post. The genal spin was labeled as one of the early developed trait however, not all the species in that group had the general spine. And according to your guy's tree if the genal spine is a convergent trait then its a homoplasy, and it doesn't exist in a common ancestor and however it was labeled as a shared driver trait(homology)(b). It's very interesting to see how a tree can be constructed in more than on way.
ReplyDeleteHi guys,
ReplyDeleteI like how you set up a list of all the traits to determine your branches and make the whole matrix neat and detailed. Our group was struggling with sorting out all the traits in lab; the spine is a very tricky one that we spent so much time figuring out. I am impressed by how detailed you guys mark and make your matrix in a different way!
Hi Zoe, it was not easy for our group to come up with the list of all the trait. We struggled a lot before coming up with this list.
DeleteI like how you guys organized your tree by using letter on the board, then making a key for it. Your tree is more complex than our tree. We had the R group the same as yours, but you guys placed the most complex number 14 with #7. They both have long genal spine, but so does #13. #13 was the hardest top sort out so I liked that you had with other trilobites that thick genal spines. Nice job.
ReplyDelete