Using DNA to Explore Lizard Phylogeny

In this activity, students explore the phenomenon of convergent evolution presented in the short film The Origin of Species: Lizards in an Evolutionary Tree. They build and interpret phylogenetic trees to infer how certain adaptations evolved among the Anole lizard populations of the Caribbean.

Students watch parts of the short film at different points in this two-part activity. In Part 1, students begin by sorting photographs of 16 species of lizards into groups, based on any criteria they consider relevant. They then revise their sorts after watching a portion of the short film, which points to key anatomical adaptations that lizards have acquired to live in different niches. Differences between the species illustrate adaptive radiation; students can generate hypotheses about possible reasons why different adaptations have evolved and infer evolutionary relationships among lizards based on their adaptations.

In Part 2, students develop explanations for how these adaptations evolved in species that live on different islands of the Caribbean by building a phylogeny using DNA sequences. They then examine whether species with similar adaptations or species that live on the same island tend to be more closely related. Finally, students compare their conclusions with those of the scientists featured in the film and synthesize their understanding of how these adaptations evolved.