Date of Award


Degree Name

Doctor of Philosophy


Science Studies

First Advisor

Dr. Robert Hafner

Second Advisor

Dr. Daniel R. Brooks


Content knowledge, strategic knowledge, and forms of knowledge organization used in phylogenetic tree construction are described to account for expert performance. A literature review is used to situate this research with respect to studies of: (a) the teaching of evolution, (b) problem-solving expertise, (c) physics and biology problem solving, and (d) the practice of phylogenetic systematics. Rationales are provided for the development of a computer-based problem-solving environment, model problems, and research problems and methodology.

Each problem consisted of a matrix of coded and polarized phylogenetic data organized by taxa and characters. Four series of research problems were constructed that varied the numbers of solutions, taxa, and characters. In addition, some problems contained a revision component that required: additions to prior solutions, restructuring of prior solutions, or increased or decreased numbers of solutions. Nine expert phylogenetic systematics participated in the research project by thinking aloud while constructing phylogenetic trees to account for the problem data matrices.

A procedural model of expert performance for phylogenetic tree construction is described with associated strategies and heuristics. Three overall strategies were described: inclusion/exclusion, order of divergence, and duplicated taxa. Each overall strategy ls represented as a pathway through the model. In addition, a new conceptual framework for understanding the nature of phylogenetic tree construction problems is described including factors that contribute to difficulty of phylogenetic problems.

The strategies related to the procedural model of expert performance are used to provide an outline of a model of desired performance. The model provides a basis for developing an approach to teaching evolution based on effects-to-causes problems. Examples are provided that illustrate how the results of this research can inform the development of a problem-based approach to teaching evolutionary biology. In addition, the implications for improved problem-solving environments for phylogenetic biology are described.

Access Setting

Dissertation-Open Access