Trilobite Tree Lab 6: The Tree They Actually Use in the Textbook.

Team Name:John’s Group

Members: Nitesh Chetry, Taylor Poffenroth, John Fortygin, Greyson Hamilton

1.   Post a Picture of your tree.

Figure 1: Phylogenetic Tree of Trilobites

  On your tree, which species is the outgroup?

Pernopsis interstricta

  Why did you choose this species?  Explain.

It was the most diverse of the organisms, causing us to believe that it separated first.

2.   According to your tree, what is one basal or ancestral characteristic?

Eyes, since the only group to not have this trait was the outgroup

  One derived characteristic?

Spots, since we only encountered 3 subspecies that expressed spots

3.   According to your tree, is the rear ‘spine’ of species 6 homologous or analogous (homoplastic) to that of species 14?  Explain.

In our tree, the rear “spine” in species 6 and species 14 was the analogous because the long tail trait for those two species did not share a common ancestor

4.   Are there any traits that were lost but then evolved again independently?  Yes.

  If so, what are they and where do they occur?

Knobby head were lost in the second branch but developed again in 19, near the right end of the tree.

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?

Looking at Team Trilomorphy, their tree had fewer branches from the initial line of lineage. There were multiple species with only one line from the original line. For our tree, only the outgroup had a single line out. I think our tree seems better because we included more explanations.

Figure 2: Phylogenetic Tree by Team Trilomorphy