This multi-day exercise is designed for a college Genetics and Evolution laboratory to demonstrate concepts of inheritance and phenotypic and molecular evolution using a live model organism, Drosophila simulans. Students set up an experimental fruit fly population consisting of ten white eyed flies and one red eyed fly. Having red eyes is advantageous compared to having white eyes, allowing students to track the spread of this advantageous trait over several generations. Ultimately, the students perform PCR and gel electrophoresis at two neutral markers, one located in close proximity to the eye-color locus, and one located at the other end of the chromosome. Students observe that most flies have red eyes, and these red-eyed flies have lost variation at the near marker, but maintained variation at the far marker, hence observing a “selective sweep” and the “hitchhiking” of a nearby neutral variant. Students literally observe phenotypic and molecular evolution in their classroom!

We present a laboratory exercise that leverages student interest in genetics to observe and understand evolution by natural selection. Students begin with white-eyed fruit fly populations, to which they introduce a single advantageous variant (one male with red eyes). The superior health and vision associated with having the red-eye-color allele confers a fitness advantage, and the students can watch the spread of the allele within the population. The increasing numbers of red-eyed flies they observe over generations demonstrate evolution by natural selection. The students concurrently learn genetic principles, including basic inheritance and X-linkage. . lectures and detailed instructions are available for download at http://www.biology.duke.edu/noorlab/ flyevolution.html, and educators are free to modify them for their individual use. MaterialsJ J J Carolina Biological Supply Natural Selection with Drosophila Kit (includes below items plus Teacher Manual and Student Guide): 171995. H o w t o d o i t