Effects of Phylogenetic Tree Style on Student Comprehension in an Introductory Biology Course

Phylogenetic trees have become an important component of biology education, but their utility in the classroom is compromised by widespread misinterpretations among students. One factor that may contribute to student difficulties is style, as diagonal and bracket phylogenetic trees are both commonly used in biology. Previous research using surveys found that students performed better with bracket phylogenetic trees across a variety of interpretation tasks. The present study builds on prior research by comparing how students interpret diagonal and bracket phylogenetic trees in the context of an introductory biology course and by expanding the style comparison to include construction tasks. Students performed significantly better with bracket phylogenetic trees for some, but not all, interpretation tasks. In addition, students who constructed bracket phylogenetic trees were significantly more accurate compared to those who used the diagonal style. Thus, our results reinforce previous research for interpretations, and the performance gap between styles extended to construction tasks. It remains to be seen, however, if such differences persist after instruction that balances the use of diagonal and bracket phylogenetic trees.