Modeling and Measuring Tree-Reading Skills in Undergraduate and Graduate Students.

Area of Science:

• Evolutionary biology education
• Phylogenetic tree interpretation
• Science education research

Background:

• Evolutionary trees are crucial for understanding evolutionary processes.
• Existing models for tree-reading skills lack empirical validation.
• Students across educational levels face challenges in interpreting phylogenetic trees.

Purpose of the Study:

• To empirically test the hierarchical structure of the synthetic tree-reading model (STREAM).
• To assess the differentiability of student skills in reading evolutionary trees.
• To develop and validate a robust model for tree-reading competence.

Main Methods:

• Developed a tree-reading test instrument based on the STREAM model.
• Assessed 592 undergraduate and graduate biology students.
• Utilized item response theory, dimensional analysis, and Wright maps to evaluate item difficulty and skill levels.

Main Results:

• No conclusive evidence supported the hierarchical nature of the original STREAM model.
• Dimensional analysis indicated a five-dimensional model best represented student skills.
• Student skill levels showed a broad scatter with overlapping item difficulties, contrary to initial assumptions.

Conclusions:

• The original hierarchical STREAM model was revised to a five-dimensional structure based on empirical findings.
• The revised STREAM model provides empirically differentiable groups of tree-reading skills.
• The revised STREAM offers a more accurate framework for understanding and assessing student competence in interpreting evolutionary trees.