You have returned to college to become a phylogeneticist. One of the first things you wish to do is determine how mammals, birds, and reptiles are related.
Like any good scientist, you need to consider all available data objectively and without a preconceived “correct” answer. In pursuit of that, you should produce a phylogenetic tree based only on morphological features that show birds and mammals are more closely related. You will then produce a totally different tree, also using morphological features, that shows birds and reptiles are more closely related. Do not forget to include all three groups in both your trees.
Based solely off the trees you produce, which relationship would you consider the more likely and why? Once you have answered that question, provide a brief summary of the “modern” understanding of the relationship between these three groups.
Rubric: Morphological Phylogenetics
| Criteria | Ratings | Pts | ||
|---|---|---|---|---|
| Mammalian/avian tree is provided | Tree includes full relationship with all 3 groups sharing multiple characteristics until the mammal/bird split from reptiles | Tree includes relationships between all 3 groups on a minimal number of features | Tree does not include all 3 groups | 3 pts |
| Reptilian/avian tree is provided | Tree includes full relationship with all 3 groups sharing multiple characteristics until the reptile/bird split from mammals | Tree includes relationships between all 3 groups on a minimal number of features | Tree does not include all 3 groups | 3 pts |
| One tree is identified as most likely | Discussion outlines multiple features for the “chosen” tree | Discussion outlines at least 1 reason for the chosen tree | Discussion does not use the trees to argue for a closer relationship | 3 pts |
| Modern understanding is discussed | At least 2 pieces of modern evidence (not only morphological) is discussed | Modern evidence is discussed | Modern evidence is not discussed or the current relationships are not properly identified | 3 pts |
| Total points: 12 | ||||
