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.
© 2013 by National Association of Biology Teachers. All rights reserved. Request permission to photocopy or reproduce article content at the University of California Press’s Rights and Permissions Web site at http://www.ucpressjournals.com/reprintinfo.asp.