“Understanding Evolutionary Trees” by T. Ryan Gregory

Evo Edu Outreach (2008) 1:121–137


Study Questions Part A, please read at least pp. 121-125 by Feb. 15, 2011 if you have not already done so and prepare to be able to answer these 10 questions, apart from your normal quiz question expectations. I have decided to spread out this assignment more than announced because of its importance. I encourage you to read ahead to read the complete article as soon as possible. I expect to post more review questions soon.


1.   How would you explain the phrase “tree thinking”?

2.   Does one need to be skilled at phylogenetic analysis to be a tree thinker?

3.   What figure did Darwin use in his most famous book, On the Origin of Species…?

4.   What is a “strictly bifurcating tree”?

5.   Among microbial life, in what sense have biologists referred to a “web of life”?

6.   Figure 2 in the article does not label the ingroup. Can you?

7.   Which member of the ingroup is most closely related to the outgroup?

8.   Fill in the blanks of this good quote from the article:

…all evolutionary trees provide the same basic information: a historical pattern of ­­–


______________________, _________________________, and


__________________________________. They do so by depicting a series of branches that

merge at points representing common ancestors, which themselves are connected through


_______________________      ___________________________     ____________________________.


9.   Briefly explain this quoted statement (p. 124): “…the more common ancestors that two species share to the exclusion of other species, the more closely related they are.”

10. Briefly explain this quoted statement (p. 125): “…Branching pattern is the only piece of information that can be reliably gleaned from a cladogram, regardless of how it is presented.”