Chapter 16: Evolution Lizard Evolution Virtual Lab Honors Biology. Name: Block: Introduction

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1 Chapter 16: Evolution Lizard Evolution Virtual Lab Honors Biology Name: Block: Introduction Charles Darwin proposed that over many generations some members of a population could adapt to a changing environment and in effect, evolve into a new species. This idea led to his understanding that living species are descended, with modification, from common ancestors. This idea is referred to as Descent with Modification. According to this idea, ALL species living and extinct are descended from one ancient, common ancestor. This produced what Darwin referred to as these Tree of Life. These changes (Natural Selection) ONLY occurs if certain conditions are met. 1. There is a struggle for existence. a. More offspring are produced than can survive, so a struggle (competition) occurs for resources. (food, living space, mates, etc.) 2. Variation and Adaptation a. Variation is present in a population and some are better suited than others b. If a heritable characteristic is present that increases an organism s chance at survival, this is considered an adaptation. 3. Survival of the Fittest a. Fitness is recognized in a population. Some have i. High Fitness: well suited for the environment and likely to reproduce ii. Low Fitness: not well suited and most likely will die without reproducing This lab takes a look at the more than 700 islands of the Caribbean which are home to about 150 species of anoles, a group of lizards of the genus Anolis. These lizards live in diverse habitats and vary greatly in size and other physical characteristics, such as leg and tail length and skin color and pattern. What happens when lizards that belong to a particular group are placed in a different habitat. PRE LAB: Make sure to read the introduction above. 1. Thinking about Darwin s idea of Descent with Modification discuss what you think might happen to the characteristics of the Anole lizard if: a. A group of lizards with short legs (normally on an island with large trees with narrow branches) is placed on an island with almost no trees, but many short, thick shrubs. b. A group of lizards with a deep red dewlap, a structure which helps the male attract a mate and defend its territory, is placed on an island which primarily has lizards with yellow dewlaps. 2. Thinking about the 3 requirements for natural selection to occur, explain how these are being represented in Question #1. (BOTH scenarios).

2 Please go to: Choose the Save/Resume tab and scroll down to saving your progress across multiple computers. READ and use your school Google login to save and resume your work. First click on the video, Welcome to the Lizard Evolution Lab and watch. Module 1: Ecomorphs. This section discusses the different categories or groups, of lizards. The lizards have been grouped by their body characteristics (Morphology) and the Ecological niches they occupy. (ecomorphs) Scientists have grouped the lizards into 4 major ecomorphs. Click on module 1 to see the 8 species of lizards we will be working with. READ the information for Module 1. Click continue. Look at the lizards and notice their common characteristics and group these into 4 pairs. Each group will have one from Hispaniola and one from Puerto Rico. Now, select a label to identify the common characteristic for each pair. Write your pairs of similar lizard species here: Common characteristic they have Go back to Modules and click Module 3 Module #3 Experimental Data: In module 1 you have learned that lizards living in certain environments have particular traits. For example, lizards living on twigs have short legs, and those found on grass and bushes have long tails. Are these traits adaptations? QUESTION TO ANSWER: Do these traits provide some sort of improved function to lizards living in those environments? EXPERIMENT: Click Begin and read the information. Click Continue and keep reading about how scientists set up an experiment. Answer the questions below: Scientists placed a: Iron Cay has: The small experimental islands only have:

3 Every year, for 4 years, the scientists collected data. Watch the video and describe how the data was collected. Click CC if you do not have headphones. Then click Back. Now, click Tutorials on the left and watch the short X-ray video on how to take x-ray measurements of body length and hind limb length. Now, take your measurements for Iron Cay and the Experimental Island and RECORD them in the data table below. PRESS Measurement Data then Continue to see ALL Relative Hind Limb Length Calculation Data. RECORD these on your data table. Then calculate #10 using the information in Relative Hindlimb Length Calculation. Calculations Relative Hind Limb Length Mean/Average) using the data above. Iron Cay (Relative Hind Limb Length MEAN/AVERAGE): Experimental Island (Relative Hind Limb Length MEAN/AVERAGE): GRAPHING: Using Google Sheets, construct a BAR GRAPH of the Relative Hind Limb Length MEAN for each population. Based on your graphed data (Relative Hind Limb Lengths MEANS), are the Iron Cay and Experimental Island lizard populations different from one another? Explain! ***Now, skip through the information presented on statistics (Looking at Sample Data, Mean and Standard Deviation, Calculating Mean and Standard Deviation, Estimating the Population Mean, Calculating SEM and 95%Cl, Compare your Calculations, Graph the Results, and Compare your Results.) Next, answer the following 6 questions: 1. In this experiment, researchers placed a pair of lizards from Iron Cay, which has large trees, in an experimental island, which has only small bushes and grass. After several generations, they measured the leg length of 10 lizards from each site. Which group of lizards had longer legs on average?

4 2. Which of the following statements accurately describes the results of the experiment 3. Anolis sagrei, the lizard species used in this experiment, is a trunk-ground anole. Which of the following statements about trunk-ground anoles is accurate? 4. The group of Anolis sagrei on the experimental island had shorter legs on average than the A. sagrei on Iron Cay. What is a likely explanation for this finding? 5. The data from this experiment provides evidence that supports which of the following claims. 6. Is this statement true or false? If you place a lizard from Iron Cay on one of the experimental island, its legs will get shorter over its lifetime. Go back to Modules and click Module 4: Dewlap colors Module 4: Dewlap Colors Fill in the blanks as you watch the video, Two groups of different animals are defined as different species when. This is called: What is the critical step in the formation of a new species of Anolis Lizards? You will examine what causes dewlaps to change by examining the dewlap colors of two anole species: Anolis cristatellus and A. cooki. Both are trunk-ground anoles that live on Puerto Rico. This population of A. cristatellus lives in a shady, forest environment and A. cooki in an open, sunny environment. QUESTION TO ANSWER: Lizards living in different habitats may have different traits, but which traits are involved in the formation of new species?

5 Click Continue. Read the instructions for Measuring Dewlap Color. RECORD the Dewlap Mean for each individual. Data Individual Dewlap Color Mean (A. cooki) Dewlap Color Mean (A. cristatellus) A. cristatellus (Sample Mean of Color Shading): A. cooki (Sample Mean of Color Shading): GRAPHING: Using Google Sheets, construct a BAR GRAPH of the Sample Mean of Color Shading) for each population. Based on your graphed data (Sample Mean of Color Shading), is the A. cristatellus and A. cooki populations different from one another? ***Now, skip through the information presented on statistics (Mean, Standard Deviation, and Standard Error Calculations, Compare your Calculations, Graph the Results, Building Your Graph, and Compare Your Results.) 1. Which anole species seems to have a brighter dewlap? (Remember that 1 corresponds to brightest and 6 to darkest.) 2. Male anoles use their dewlaps to communicate and to attract females of their own species. What is an adaptive explanation for why the dewlap of one species is brighter and that of another species darker 3. According to Dr. Losos, dewlap color is an adaptation to

6 4. The population of Anolis cristatellus that you analyzed lives in a shady, forest environment and A. cooki in an open, sunny environment. Are the results you obtained consistent with what Dr. Losos describes? 5. True or False: If you put a male Anolis cooki lizard with a dark dewlap in a shady environment, its dewlap will become much brighter. 6. No two species of lizards living in the same area have the same dewlap color. The different dewlaps keep species Module 4 Summary: In this last module, you learned that dewlap colors change as groups of lizards become isolated in different environments with different intensity of light. Once groups of lizards evolve different dewlap colors how will you know they have become different species? Whole lesson Summary: watch and listen to this summary video and write 7-8 facts mentioned in the video

7 Answer the following Questions: 1. How did the lizard species with similar body types evolve on all the islands? 2. Are these traits adaptations? In other words, do they provide some improved function to lizards living in those environments? 3. Lizards living in different habitats may have different traits, but which traits are involved in the formation of new species? At the beginning we asked these 2 questions, Why are there so many species of anoles? How did they evolve? Please summarize your answers and cite evidence within this activity for your findings.