“Don’t Judge a Shell by its Cover”

by Colleen Worrell, Secondary Technology Integration Coordinator

Last week AP Bio students used an online activity, “Exploring Biodiversity,” to compare DNA sequences. As teacher Michelle Odierna explained to her students, like researchers, they could take advantage of the computer to do the hard work of comparing the complex DNA sequences in order to examine evolutionary relationships. Having gone through the laborious process of comparing sequences by hand on the previous day, students really appreciated the power of technology! Rather working painstakingly through long, tedious series of letters that comprise DNA sequences, students could use a digital application that enabled their laptops do the hard comparative work for them.

Students first ran a practice simulation with molluscs in order to confirm that tonnoids and cowries are more closely related to each other than to neogastropods. Then students were able to enjoy the inquiry-based portion of the activity when they compared the relatedness of several species of their choice relatively effortlessly. The app did the work to show that the more similar the sequence, the more closely related the species. It also was able to draw evolutionary trees to depict the relatedness that the sequences suggested.

Using laptops for the hard part of the lab made doing the analysis to discover various evolutionary relationships fun. Here are snippets of conversations from various class sessions:

Did you know the panda is more closely related to the silverleaf whitefly than to the ostrich?

What’s the scientific name for a Black Rhino?

Did you know that the Macaroni Penguin is more closely related to a flamingo than a Blue-Footed Booby?

Did you know there’s a Red Footed Boobie and a Nazca Booby? I love Boobys….

Did you know a Poison Star Frog is closer to a Tree Snake than a Moray Eel?

What third animal should we compare the Dumbo Octopus and the Blob Fish to?

Students learned that, as Ms. O put it, that you “can’t judge a shell by its cover”: it’s the DNA that counts the most.


Image credits: flickr.com, FDA website.