Lizard Groupings and Ecotypes: Observations and Hypotheses

Lab 9: Lizard Worksheet: Name: Q1: A) How were the lizard groupings you and your lab partner came up with similar or different from one another? In my lab, I grouped lizards according to their location and leg sizes. A. sheplani and A. occultus were in the same group because they both had short legs. A. olssoni and A. pulchellus were in the same group because they both had long legs. A. evermanni was the only lizard in the third group because it was the only ground lizard that I saw. A. cyobtes, A. coelestinus, and A. cristatellis are in the same group because they all are tree species. My partner grouped A. sheplani and A. occultus together as twig species. A. olssoni and A. pulchellus were in the same group and they were grouped under long legs, the same thing I did. The two green lizards were grouped together, A. evermanni and A. coelestinus. A. cyobtes were in a group on its own and labeled as a tree species. A. cristatellus was in the group gray lizards. B) With your partner, come up with a hypothesis for how you think the 8 lizard species might be related to one another. The 8 lizard species might be related to one another through a shared common ancestor. The lizards that are more morphologically similar, long tails, color, etc. shared a more recent common ancestor with one another than they did with other species. Q2: Did your measurements match those of the scientists fairly closely? Why do you think there might be variation between measurements?

My measurements for body length and tail length are fairly close. My measurements for hindlimb length however are different from the reference measurements table. The reason for this is human sampling error. I see that most of the time, the value I get for hindlimb length is less than the reference value. This might have been because I did not take into account the complete length of the fingers when measuring the hindlimb length. Q3: What are the relative leg and tail lengths of the various lizard species? Q4: List ecotypes for each species according to graphs: Species Ecotype according to tail-hindlimb relationship A. evermanni Trunk-ground A. cristatellus Trunk-crown A. occultus Twig A. pulchellus Grass-bush A. olssoni Grass-bush A. coelestinus Trunk-crown A. cybotes Trunk-crown A. sheplani Twig Q5: Consider the following two hypotheses… H1: Anolis lizards diversified into several ecotypes on one island. The various ecotypes then dispersed to other islands, and eventually evolved into separate species. H2: A single Anolis species arrived on each island, and speciated to produce the different ecotypes, which look similar on different islands due to convergent evolution. How would you use genetic data to distinguish between these hypotheses? What would you expect to see if H1 is correct vs. H2? If H2 is correct then I would expect to see that all the lizard species on an island form a monophyletic group as they speciated from a single common ancestor. If H1 is correct then I

would expect to see polyphyletic groups in my data because different lizards diversified to form the various ecotypes we see today. And these are polyphyletic because we don’t know what species arose from what but we can figure out if they are more closely related to each other than other species. Q6: Paste a copy of the provided phylogeny and your MABL tree below. Are there any differences? Do they seem like really important differences or minor differences, and why? The relationships between the species in my generated graph and the other graph are the same. Both graphs show that Leicephalus carinatus is related to our lizard species. And the relationships between the individual lizard species observed are the same in both graphs. I do not observe any clear differences. Q7 : Paste your phylogenetic trees colored by ecomorph and island below .

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The above is colored by ecomorphs. The tree above is color coded according to the islands. Q8 : Based on these trees, fill in the blanks in the following paragraph to form a hypothesis of the evolutionary history of these species, and justify your answers below: An ancestral population of lizards lived on the island of Hispaniola , living in/on trees They began to diversify, and some of these lizards then colonized the island of Puerto Rico . There, they diversified further, and some began to specialize in living in/on Trunk ground . Finally, some of these new specialists migrated to Hispaniola _ and diversified again . We can see from the second graph that the species Anolis shelpani is the one which was diversified before any other species, and that species lived in Hispaniola. Thus, I can conclude that the lizards lived on the island of Hispaniola. I can see that the oldest species lived on trees and from there it started to live on tree-ground, tree-crown, and finally on twigs. The monophyletic group which consists of Anolis olssoni and Anolis coelestinus is also found in

Hispaniola even though the species which emerged before and after this group lives on the islands of Puerto Rico. So, from this I can conclude that some of the new species migrated back to Hispaniola. Q9: What are the relative leg and tail lengths of the two populations? Q10: Why is it important, when trying to determine if two populations differ, to measure multiple individuals from each? It is important to measure multiple individuals from each population because no one individual is representative of the whole population. So a larger sample size would allow us to have data that is less biased.

Q11: How do the populations differ in relative leg length? Why do you think this difference exists? Individuals on the Iron Clay island have longer hindlimbs compared to the experimental group. This occurs due to the fact that these islands have different environments, and natural selection selects traits based on the particular environment that a species is in. Q12: Summarize what you have learned about the patterns of morphological diversity in anoles and how these patterns originated.

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I have learned that morphologically similar anoles live on the same islands. Occasionally, we would see similar looking species on different islands. This occurs because of convergent evolution. I have learned that just because species share a common habitat, tree trunk or grass, it doesn’t mean that they are more closely related to one another. The Anoles lizards lived on the same island. Due to competition in food sources, these lizards diversified and started habitating different parts of the tree. Some of these species migrated to different islands. Because the new islands have a different environment than the previous one, the species were under different controls and natural selection selected for different traits. So, these species further diversified. And some of the species from different islands ended up looking morphologically similar because natural selection was selecting on similar traits.

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