Meeting Abstract

P2.70  Saturday, Jan. 5   Assessment of student conceptions of evolutionary trees BLACQUIERE, L.D.*; HOESE, W.J.; California State University, Fullerton lblacquiere@csu.fullerton.edu

Biologists use evolutionary trees to depict hypotheses about the relationships among taxa. Trees possess lines that represent lineages, internal nodes that represent where lineages become evolutionarily isolated from one another and terminal nodes that represent the taxa under consideration. Interpreting a tree (i.e., “tree-thinking”) is an important skill for biologists yet many students struggle when reading evolutionary trees. Common documented misconceptions include using morphological similarity, internal node counting or terminal node proximity, instead of identifying internal node that represents the most recent common ancestor, to determine relationships among taxa. We developed an assessment that tested whether students were using common ancestry or one of the other, non-scientific, strategies to determine relationships among taxa. We interviewed 12 students in introductory biology following instruction on evolutionary trees, verified common problems students had interpreting trees, and developed a diagnostic test that we used to determine whether students consistently employed one strategy to interpret evolutionary trees. We found that a minority of students used tree-thinking when interpreting trees. Those students who used alternative strategies to interpret trees did not consistently use a single alternate strategy; alternate strategies of all types were used preferentially to tree-thinking strategies by these students. This study provides instructors with a tool with which they can determine how well students understand how to interpret evolutionary trees.