Table 1.

Descriptions and prevalence of skills (based on subset of pretest questions)

Skill	Description	Percent of population lacking this skill (n = 410)
S1: Reading Traits from Tree	Given a tree with trait transitions marked, the student is able to correctly deduce the traits of a particular species on the tree.	65%
S2: Deducing Ancestral Traits	Given the terminal taxa (species) on an evolutionary tree with sets of traits given for each extant species, the student is able to deduce the most likely traits shared by the common ancestor of those species.	84%
S3: Reconstructing Trees	Given a small set of extant species with no convergence or loss of derived traits, and the common ancestor of these species, the student is able to draw an evolutionary tree showing the most likely phylogeny.	70%