LOVETT, J.A.; SUNY College at Geneseo: Introductory Laboratory for Systematics

We have developed an introductory biology course laboratory to illustrate the creation of phylogenetic trees based on shared morphological characters and the correlation between such trees and the trees based on molecular data. Such laboratory exercises usually try either to simulate production of a dichotomous key using hardware (nuts, bolts, screws) or use computer databases to compare DNA or protein sequences. The first approach is not analogous to the way phylogenetic trees are created and the second approach often creates the impression that traditional methods are inadequate or misleading in comparison with the newer molecular methods. We have developed a laboratory that combines a simulation of phylogenetic tree formation with comparisons of immunological cross reactivity. Trees are constructed from two different sets of images, one an assortment of various kinds of furniture and the second an assortment of ungulates. The sets contain thirty two and fifty seven images respectively. Sera used in the antibody:antigen portion of the exercise are of ungulates whose images are included in the image set. The phylogenetic relationships deduced from the antibody:antigen similarities are then compared with the phylogenetic trees created by students and based on morphological characters visible in the ungulate images. The traditional methods of creating trees is corroborated by the molecular data rather than contradicted. Students also discover that there are reasonable alternative trees possible and that attempts to initially categorize specimens into arbitrary categories (e.g. horns or no horns, long or short hair) does not work. Several alternative ways to present the laboratory using live or preserved specimens rather than photographic images and several different immunological or molecular database methods will be included.