Meeting Abstract
Evolutionary trees present hypotheses of the relationships among taxa. Some undergraduate biology students have trouble properly interpreting relationships depicted in these trees. Instead of using the most recent common ancestor (MRCA), many students use alternate strategies in reading trees, including node counting, morphological similarity, or tip proximity to determine relationships. I examined these alternate strategies simultaneously along with the MRCA, to identify the most commonly used strategies and the consistency of their use. I developed a multiple-choice questionnaire to test students’ use of these three alternate strategies simultaneously. I administered the questionnaire to 217 undergraduate students in their first core biology class after they received instruction on evolutionary trees. The questionnaire was highly reliable (α = 0.86). The proportion of students who chose tip proximity at least once was highest, followed by node counting, with morphological similarity used least. Over 48% of the tested students missed at least one question, 37% at least two, 32% at least three, and 23% of students missed at least four questions. The type of alternate strategy used by individual students was not consistent throughout the questionnaire; patterns of the structure of the tree appeared to influence the strategies used by students. This questionnaire provides a better understanding of how students determine relatedness among species and can help instructors of introductory biology courses to improve student understanding of evolutionary trees. Future research will use eye-tracking equipment to determine if tree-interpretation strategy matches student eye movements.
