Hhmi Lizard Evolution Virtual Lab

[Onfroi Baird]

TheCaribbean is home to about 150 species of anole lizards. In this lab, students investigate how so many species of anoles evolved. The lab includes four modules that cover different concepts in evolutionary biology, including adaptation, convergent evolution, phylogenetic analysis, reproductive isolation, and speciation. In each module, students engage in key science practices, including taking measurements to collect data, constructing and interpreting graphs, and performing statistical analyses.

This film explores the adaptation of anole lizards (genus Anolis) to habitats common across the islands of the Caribbean. The anoles are excellent examples of adaptive radiation, convergent evolution, and speciation through reproductive isolation.

Working in the islands of the Caribbean, biologist Jonathan Losos discovered traits that enable dozens of anole species to live in different vertical niches in the forest. Differences in limb length, body shape, and toepad size reflect adaptations to life on the ground, on thin branches, or high in the canopy. Remarkably, similar combinations of these traits have evolved independently on different islands, a phenomenon known as convergent evolution. The film also describes how new species of anoles are formed due to variations in the color of their dewlaps, a reproductive trait that determines their mating behavior.

Virtual Lab Student Handout Lizard Evolution Virtual Lab LIZARD EVOLUTION VIRTUAL LAB Answer the following questions as you finish each module of the virtual lab or as a final assessment after completing the entire virtual lab. Module 1: Ecomorphs 1. At the beginning of the virtual lab, you were asked to sort eight lizards into categories. What criteria did you initially use to make your groups? Did you revise your criteria later? Why? 2. An adaptation is a structure or function that is common in a population because it enhances the ability to survive and reproduce in a particular environment. Provide one example and an explanation of one adaptation in the Anolis lizards. 3. Provide one evolutionary explanation for why lizards living in the same part of the habitat (i.e., grass) would have similar characteristics. 4. What is an ecomorph? Provide one example from the virtual lab. 5. How is an ecomorph different from a species? 6. Explain how a particular body feature of one of the lizard ecomorphs from the virtual lab is an adaptation to their particular niche. www.BioInteractive.org February 2015 Page 1 of 5

Virtual Lab Student Handout Lizard Evolution Virtual Lab Module 2: Phylogeny 1. In module 1, you identified which species of lizards were most similar to one another based on relative limb length and toe pad size. In this module, you determined which lizards are more similar to one another based on what type of information? 2. Are the species of lizard that are more similar to one another according to body type also more closely related based on the results obtained in this module? Explain your answer. 3. The figures below show two phylogenetic trees similar to the one you constructed in the virtual lab but with more lizards. The trees below show the evolutionary relationships among species from four ecomorphs from the four largest Caribbean islands. www.BioInteractive.org Figure 1. Phylogeny of anole lizards on four of the major Caribbean islands color-coded according to geographical distribution. Light dotted line, Puerto Rico; small dashed line, Cuba; large dashed line, Hispaniola; and solid line, Jamaica. Figure 2. Phylogeny of anole lizards in the four major Caribbean islands colored in according to ecomorph. Light dotted line, twig; small dashed line, trunk-ground; large dashed line, trunk-crown; solid line, grass- bus. February 2015 Page 2 of 5

Virtual Lab Student Handout Lizard Evolution Virtual Lab Module 4: Dewlap Colors 1. Anolis cristatellus and A. cooki are both trunk-ground anoles that live on Puerto Rico. A. cristatellus lives in a shady, forest environment, while A. cooki lives in an open, sunny environment. What is an adaptive explanation for why the dewlap of one species evolved to be brighter and that of another species darker? 2. From the bar graph generated in the virtual lab (see below), how do the dewlap colors of the two species compare? 3. How would you determine whether the difference between the two populations is statistically significant? 4. If a species of anoles with dark dewlaps colonized a heavily forested island, predict what would happen over time to the color of the dewlap. Using your knowledge of natural selection and genetics, explain your prediction. www.BioInteractive.org February 2015 Page 4 of 5

The virtual lab includes four modules that investigate different concepts in evolutionary biology, including adaptation, convergent evolution, phylogenetic analysis, reproductive isolation, and speciation. Each module involves data collection, calculations, analysis and answering questions.

HHMI produced several fantastic videos and learning modules perfect for learning about anoles, ecology, and evolution in the classroom and at home! Each of the activities also comes with handy educator materials to make sure your newly homeschooled students gets the most out of these resources.

Michelle Johnson (Trinity University) has developed a wealth of teaching resources for students of all ages made available on her site Lizards and Friends. Some of these activities require a live lizard (which some of our readers in the southern US and Caribbean might have access to in their backyards), such as an guided activity to understand how lizards get energy from their food, but other activities only require your creativity and thought, such as this worksheet exploring food webs involving anoles. Also featured on this site is a fun activity developed by Thom Sanger on dewlaps and signaling, which might be difficult to do at home while maintaining social distancing, but could be done safely over video chat with friends or even across the street with your neighbors!

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