Tree Interpretation Problem set key


[Video clips coming soon]


1. Answer the following questions on this tree:

a. Which are the two most closely related species? Troll and Dwarf

b. Which is the most primitive of these species? Hippogriff

c. Which of these is probably the outgroup? Gump

d. Which is most distantly related to the Gremlin other than the outgroup specie? Griffin

e. Circle the last common ancestor of the Hippogriff and Gremlin. (see above in red)

f. Redraw this tree as a phenogram.

By the way, here is the same tree as a splayed-out, rootless dendrogram:

2. Answer the following questions about this tree:

a. Which are the two most closely related species? Limulus and Drosophila

b. Which of these is probably the outgroup? Paramecium

c. Based on this as the outgroup, circle the last common ancestor of the remaining creatures. (done in red)

d. Now circle the root of the tree (again, assuming this as the outgroup). (Trick question - it's the same thing!)

e. Circle the two main groups in this tree (other than the outgroup). (Done in blue)

f. Which is most distantly related to the Drosophila other than the outgroup specie? Stella

g. Which specie in ths tree is most closely related to Homo? Purpurea

h. Redraw this tree as a phenogram.

3. Answer the following questions about this tree:

a. Which organism is the closest relative of Chromatium vinosum? Escherichia coli

b. Which organism(s) is/are the outgroup? Sulfolobus solfataricus and Methanococcus vannielii

c. Where, then, is the root of the tree based on this outgroup? (please circle) (in red)

d. What is the evolutionary distance between Thermus thermophilus and Thermomicrobium roseum? 0.23

e. What is the evolutionary distance between Chloroflexus aurantiacus and Methanococcus vannielii? 0.59

f. Which organism(s) is/are most closely related to Chloroflexus aurantiacus and Thermomicrobium roseum? Thermus thermphilus

g. "EM3" is an unknown organism - what is it's closest relative on this tree? Thermotoga maritima

h. Excluding the outgroup, which is the most primitive organism (or at least sequence) in this tree? Thermotoga maritima

i. Excluding the outgroup, which is the most highly evolved organism (sequence) in this tree? Escherichia coli

j. Circle the last common ancestor of Chromatium vinosum and Deinococcus radiodurans. (in blue)