Improvement of Undergraduate Molecular Biology Laboratory Curriculum

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The primary objective of the Molecular Phylogeny project is to introduce a unifying concept into several courses in the curriculum. It is inculcating a thorough understanding of evolutionary concepts by complementing traditional teaching styles, concepts, and materials with modern approaches, including discovery-based learning, modern phylogenetic approaches, and the materials and methods used by scientists in the field. Instruction in molecular evolution and phylogenetic analysis begins in the freshman course with a discovery-based exercise on the classification and evolution of organisms. Students are given the 5S rRNA sequences of several invertebrates, asked to make pairwise comparisons between species, and asked to construct plausible evolutionary trees. Discordance between morphological- and molecular-based phylogenies are discussed. In this exercise, students develop an intuitive grasp of the principles of molecular phylogeny that will be studied in detail in later courses. As a follow-up to this exercise and a prerequisite to subsequent studies, students are given an introduction to molecular biology databases and software on the Internet. Specifically, they are directed to the NIH and EMBL, the Ribosomal Database Project, and the CLUSTALW and PHYLIP programs. Homework assignments involve searching and aligning selected 5.8S rRNA and short polypeptide sequences. In Botany, students explore the relationships among nonvascular and vascular plants using small and large subunit rRNAs and rbcL sequences. They obtain sequences from the GenBank, align them using CLUSTALW, then construct phylogenetic trees using PHYLIP. The students are guided extensively through this exercise as they test a model of plant evolution. In Zoology, students re-explore the relationships among phyla begun in the freshman class, as they look in more detail at specific issues in animal evolution. In advanced courses, the principal investigators work with the instructors to identify discipline-specific p roblems for student exploration. Students are encouraged to develop problems using models from the literature. Directed research projects are becoming possible through the acquisition of DNA sequencing equipment. Specific projects enable undergraduate students to investigate problems in diatom, ciliate, and crustacean evolution under the direction of experts in these areas. Results from the project can be disseminated through the Commonwealth of Pennsylvania University Biologists, on-line bulletin boards, and traditional education journals. Other universities that still have a traditional organismic bias to their freshman and sophomore curricula can make the transition to a concept-based curriculum more smoothly if they proceed as this project.