Lab 5 -Trilobite Tree-AB: Creating a Phylogenetic Tree of Trilobites Using Morphological Traits.(Octavia, Tianzhi, Michelle, Eloina)
- Post a Picture of your tree. In your tree, which species is the outgroup? Why did you choose this species? Explain.
We considered that Peronopsis interstricta would be the outgroup in our tree because this organism has less similarities in appearance or traits compared to the rest of the species proving it shared a more distant common ancestor with the others.
Figure 1. Photo of trilobite tree built during the lab on Jan.17th.
Figure 2. Detailed Trilobite tree includes the traits and the species.
2. According to your tree, what is one basal or ancestral characteristic? One derived characteristic?
According to our tree, an ancestral characteristic is a striped axis. One derived
characteristic is a rounded pygidium.
3. According to your tree, is the rear ‘spine’ of species 6 homologous or analogous (homoplastic) to that of species 14? Explain.
The rear spine of species 6 is analogous(homoplastic) to species 14 because the species are in different monophyletic groups and do not share a recent common ancestor indicating that the trait was independently developed by each species.
4. Are there any traits that were lost but then evolved again independently? If so, what are they and where do they occur?
Species 7 (Paradoxides gracilis) shows to have had the trait for double pleuron spines but was lost and appeared again further down the tree in species 10,19, 11, and 17.
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? Why?
We compared our tree to “Boys Who Cry” tree and noticed that the biggest difference is that our tree specifies the traits that we used to organize our species along the branches which makes it easier to read and understand.
No comments:
Post a Comment