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BIO-106-1H LAB- WEEK 1 FARIHA TASNIM LAB #1: Natural Selection and Ecomorphs

BEFORE LAB • Read the Introduction and skim the lab exercises below. • Read Sadava et al., chapter 19.2-19.3 (pp. 424-433 [note pages are displayed in the eBook]) BRING TO LAB All online now! Note LAbster is accessable via Blackboard.. if it isn’t, we can’t use the package…

OBJECTIVES 1. Learn how natural selection can rapidly shape randomly generated variation into adaptations. 2. Learn how traits are measured and vary continuously within and among populations 3. Learn how similar habitats can shape evolutionary patterns (ecomorphs)

INTRODUCTION As (hopefully) a review from high school remember that natural selection as envisioned by Darwin has 4 components, and if all four are present, we expect traits to evolve over time. 1. There must be variation among individuals in a population. Darwin was much more focused on variation within species, rather than among. This was new! 2. That variation must be heritable – passed on in some way. Note that Darwin didn’t understand genetics, he instead had his own theory of inheritance (gemmules) that wasn’t that different from Lamark. 3. There must be overproduction – more offspring produced than can possibly survive and reproduce, and what affects reproductive success? 4. Some of the heritable variation leads to different average reproductive success (fitness). So now we have the building blocks of an evolutionary definition of fitness – the average reproductive success of individuals having a given trait. Note that fitness is not something that individuals have. Individuals have reproductive success, but not fitness. Traits have fitness; an average effect of that trait on reproductive success of individuals. We will watch a short video to see how strong natural selection can be, then another to look at another evolutionary mechanism that can change gene frequencies, most powerful in small populations like this class. Finally, we will see how similar ecological challenges and the

availability of niches can repeatedly favor similar adaptations, using the natural laboratory of large and small islands in the Caribbean. Foraging behavior of predators and the evolution of crypsis. A classic example of evolution in action is the spread of industrial melanism in the peppered moth, Biston betularia. Industrial melanism is an increase in frequency of dark forms that more closely match the darker trunks of trees when lichens die and coal soot accumulates, as it did following the industrial revolution in the 19th century. The frequency of the dark form of peppered moths, earlier shown to be a genetic polymorphism in the species, increased in frequency in the 20th century. HBD Kettlewell (1955, 1956) wanted to show that it was the foraging behavior of birds that led to the evolved change in frequency of the different morphs. He did this by placing light and dark moths on lichen and soot covered surfaces in captivity and observing the capture rates of each form by birds in those cages. Then he placed light and dark forms in first a polluted wood and attempted to recapture them later using UV lamps and traps, and then a year later he replicated the experiment in an unpolluted wood. In each case the recapture rate of the morph matching that habitat was higher. Interestingly right after Kettlewell’s experiments pollution controls and the larger change from coal to oil as the primary fossil fuel led to an increase in lichens on tree trunks and less soot deposition, and a recovery in the frequency of lighter morph moths.

Above: On the left is a light form of the peppered moth matching a light-colored background (Photo by Andy Phillips). To the right are a pair of moths mating, one light ‘ typica’ and one dark ‘carbonaria’ (Ilik Saccheri/Science/AAAS). While the peppered moth is the most famous example of rapid change in coloration in natural populations, there are perhaps better examples that have been described of evolution both due to human induced changes (anthropogenic change), and natural environmental variation. One very well studied example on only a moderately longer time scale is the evolution of dark fur color in pocket mice living on recent (6,000 yo) lava flows.

RAPID EVOLUTION OF FUR COLOR IN POCKET MICE Rock Pocket mice are small nocturnal rodents living in the Southwestern US and Mexico. Your lab instructors will introduce their history and natural history, and then you will watch the interactive video https://media.hhmi.org/biointeractive/interactivevideo/pocketmousequiz/ The playback may be more stable if you open it from the hhmi launch page, https://www.biointeractive.org/classroom-resources/interactive-assessment-naturalselectionandadaptation . After working through that exercise, print out the results to a pdf file and

either email or show your instructor, and then the class will discuss the example as a group. Your instructor should then split you up in pairs to work through the following worksheet (not a quiz). 2 As before, email the answers (either by opening text boxes in the pdf to modify it to turn in, or just typing a word file with numbered answers) to your lab instructor.

The Makingthe Fitte t: Natural Selection and Adaptation Fariha Tasnim _________________________________ NAME 1.

________11/20/2020_____________ DATE

Define “mutation.” Mutation is the change in the chemical letters that make up our genes and the change is random.

2.

Is the following statement true or false? Justify your answer in one or two sentences: “Mutations are caused by selective pressure in the environment.” This statement is false because mutations are caused by genes DNA.

3.

Is the following statement true or false? Justify your answer in one or two sentences: “The same mutation could be advantageous in some environments but deleterious in others.” This statement is true because the environment or selective pressure determines whether a mutation is beneficial. At times animals can blend in the environment and not seen by the predators but in other places, animals stand out and can be seen easily.

4.

Is the following statement true or false? Justify your answer in one or two sentences: “The appearance of dark colored volcanic rock caused the mutation for black fur to appear in the rock pocket mouse population.” False as selective pressure does not cause mutations but rather determines whether a mutation is advantageous or harmful in a particular environment.

5.

Explain how the environment plays a role in changing the frequency of a mutant allele in a population.

Some traits could be more beneficial or deleterious in certain environments than others. As a result, organisms with the mutations that result in those traits that make them better suited to a certain environment are more likely to have offspring and pass to their genes. Over time, this results in an increase in the frequency of mutations that encode advantageous traits for that environment or, conversely, a decrease in the mutations that influence deleterious traits in that particular environment. It makes a species mutate and once that one animal does its offspring will also mutate and so will its offspring.

Published August 2012 October 2013 www.BioInteractive.org

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Revised Page 1 of 4

The Making of the F test: Natural Selection and Ad ptation 6.

As you saw in the film, rock pocket mice evolved to have dark-colored fur in certain habitats. In three to five sentences, explain how this trait increased in frequency in the population. Include the following key terms: “fitness” (or “fit”), “survival” (or “survive”), “selection” (or “selective”), and “evolution” (or “evolve”). Natural selection favor individuals with dark colored fur in certain habitats like dark colored volcanic rocks. Rock pocket mice with dark-colored fur were more fit on dark-colored volcanic rock because visual predators could not see them well. As a result, more of the dark-colored mice survived and reproduced. This caused the population of rock pocket mice to evolve to have more individuals with dark-colored fur. Once the mice started evolving their level of fitness also increases majorly.

7.

Near the end of the film, Dr. Sean B. Carroll states that “while mutation is random, natural selection is not.” In your own words, explain how this is possible. Mutation basically happens when our genes get arbitrarily mixed up whereas; natural selection chooses the best to survive. Natural selection acts on traits those results in the mutation. However, it does not actually reason the mutations to appear in the population, many mutations appear randomly.

8.

Suppose you are studying a recently discovered population of rock pocket mice with darkcolored fur that lives on volcanic rock. You take a DNA sample from a member of this new population and determine the DNA sequence of a gene known to play a role in fur color. The sequence you get is identical to that of the same gene in another rock pocket mouse population with dark-colored fur that lives on a different patch of volcanic rock. Which of the following could explain this observation? a. The mice in the two populations evolved from the same ancestral population.

The volcanic rock caused the same mutation in each rock pocket mouse population, resulting in dark coloration. c. The same mutation spontaneously arose in the two different populations. d. Both (a) and (c) are possible. e. All of the above are possible. b.

9.

Ans: d, both a and c possible For rock pocket mice, which of the following contributes to selective pressure favoring darkcolored fur? Write “yes” or “no” next to each of the four possible responses. There may be more than one yes response. Predators : Yes Rock color: yes

10.

Genetic mutations : No Availability of food color for the rock pocket mice: No

Suppose you are studying a new population of rock pocket mice in Arizona. These mice live on a recently discovered patch of dark-colored volcanic rock. This environment does not have nearly as many visual predators as in previously studied areas in New Mexico. You observed the following numbers of light- and dark-colored mice on this new patch of rock.

a.

In one or two sentences, summarize the data presented in the graph. Ans: From the graph it is observed the numbers of both light- and dark-colored mice are relatively stable. The number of dark mouse has always been almost same. However there was a little fluctuation in the number line of light mouse, yet overall stable.

b.

Provide one possible hypothesis that would explain the observed data. Be sure to include the following key words in your answer: “selection” (or “selective”), “fitness” (or “fit”), and “survival” (or “survive”). Ans: As this environment does not have nearly as many visual predators as in previous the difference in fur color does not make difference to the overall fitness of the organisms and therefore their likelihood of survival. These two colors equally suited and survive. So, natural selection does not affect the frequency of these traits.

You next decide to move 50 of these newly discovered light-colored rock pocket mice from Arizona to a colony in New Mexico that also lives on dark-colored volcanic rock. You also move 50 darkcolored mice from the New Mexico colony to the Arizona colony. You monitor the populations for five years and observe the following.

c.

In one or two sentences, summarize the data presented in the graphs above.

Ans: The population of dark-colored mice in New Mexico is increasing whereas the population of light-colored mice is decreasing. In Arizona, the light- and dark-colored mouse populations’ numbers are stable.

d.

Provide an explanation for these observations. Be sure to include the following key words in your answer: “selection” (or “selective”), “fitness” (or “fit”), and “survival” (or “survive”).

Ans: In New Mexico, natural selection affects the frequency of dark-colored fur. Dark-colored mice are less visible to predators. This increases their fitness in this environment and therefore more likely to survive and reproduce. In Arizona, where there are less visual predators so there is no selective advantage to light- or dark-colored fur. Different colored mice are equally fit and so equally likely to survive and reproduce.

Before your experiment above, you take a DNA sample from one dark-colored mouse in each population and sequence a gene known to play a role in making mice dark colored. You discover that the dark-colored mice from Arizona have a different allele of this gene than the dark-colored mice from New Mexico. e. Design an experiment to test which population of dark-colored mice is more evolutionarily fit in an environment of your choice. You may want to use the above experiments as a guide. Be sure to state your hypothesis, as well as what type of data you will record. It is hypothesized that the population of dark-colored mice from Arizona have more evolutionarily fitness than the population of dark-colored mice from New Mexico in a desert with black sand. To experiment this hypothesis, 50 dark colored mice can be taken from each population to place them in a black sand desert. Each population will be on a separate patch of identical black sand in every way. However, they can be kept separated to prevent interbreeding. Every year for five years, the numbers will be counted.

ECOMORPHS HHMI VIRTUAL LAB In lecture you will soon discuss the definitions of species, the most common being the group of all potentially interbreeding individuals capable of producing fertile offspring. In this part of the lab we will learn how to define Ecomorphs, species that may or may not share a common ancestor recently (may not be closely related) but share an ecological niche, and so are similar in morphology (shape) and behavior to match that niche (after E. E. Williams). This week and next you will replicate some of the experiments carried out by Jonathan Losos and colleagues to understand rapid evolution of ecomorphs in a natural laboratory, the large and small islands in the Caribbean, some of which have multiple anole lizard species and others that have had previous populations wiped out by storms, so they can be manipulatively inoculated with lizards to see how they evolve. Your lab instructor will break you up into pairs in Collaborate, but you’ll each have to open the following link individually, even if you discuss the activities together (sharing screens in collaborate isn’t that stable). Open the link Lizard evolution virtual lab (https://media.hhmi.org/biointeractive/vlabs/lizard2/) . If that doesn’t work, go first to HHMI lizard evolution launchpad (https://www.biointeractive.org/classroom-resources/lizard-evolution-virtual-lab ). We will carry out module 1, work in pairs to first arrange and label the 8 anole species into groups. When you do that, write here what your groups and labels are. The program will store them for today, but it’s useful to write down as well to work faster later. You don’t need a set number of groupings, determine the traits you will use with your partner. _____________________________________ Group __________________ Sp1 ____________________ Sp2____________________ Sp3____________________ ____________________

Group __________________ Sp1 ____________________ Sp2 ____________________

Group __________________ Sp1 ____________________ Sp2 ____________________ Sp3 ____________________

Group __________________ Sp1 ____________________ Sp2 ____________________ Sp3 ____________________

Group __________________ Sp1 ____________________ Sp2 ____________________ Sp3 ____________________ _____________________________________ Result

Group __________________ Sp1 ____________________ Sp2 ____________________ Sp3 ____________________

Sp3

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Fig: Pic of lizard virtual lab completion Work through module 1 individually, you’ll find that using a calculator from the dock or your own calculator is easier than the one you can call up in the virtual lab. Finally complete with your partner the worksheet at the end of this handout in lab. If there is time your instructor can review it in class.

Virtual Lab Lizard Evolution Virtual Lab

Student Handout

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?

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From the video which was played during the class I have noticed legs of different anoles vary according to their habitat. Based on that, I used the criteria on the size of anoles’ legs. I wanted to base the experiment on that.

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.

The short legs on the sheplani hispaniola anolis lizard is one adaptation, This is most likely because the thin branch it lives on. The short legs make the lizard able to hold the branch/twig better and survive longer because it does not fall off.

3. Provide one evolutionary explanation for why lizards living in the same part of the habitat (i.e., Lizards in the same habitat would have similar characteristics

To survive in a particular location certain traits have evolved in a particular organism. Therefore, lizards in the same habitat have the characteristics that are most fit for survival, so most lizards in that habitat would exhibit those most fit characteristics and these are similar for lizards living in the same location

4. What is an ecomorph? Provide one example from the virtual lab.

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Species with the same structural habitat /niche and similar morph for morphology or shape and behaviors but not necessarily closes phyletically. An example the sheplani hispaniola and occultus Puerto Rico lizards both have short legs.

5. How is an ecomorph different from a species?

An ecomorph classifies the organism as having similar body types and niches. However, species have other different characteristics such as color or look. By this way ecomorph is 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.

One of the lizard ecomorphs, the occultus Puerto Rico anole has short legs because it needs to be able to stick to/crawl on slim twigs in their habitat.

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February 2015

References Rudge, D. W. 2005. Did Kettlewell commit fraud? Re-examining the evidence. Public Understanding of Science, SAGE Publications, 2005, 14 (3): 249-268. 10.1177/0963662505052890. hal-00571065 Kettlewell, H.B.D. 1955. Selection Experiments on Industrial Melanism in the Lepidoptera. Heredity 9: 323–42. Kettlewell, H.B.D. 1956. Further Selection Experiments on Industrial Melanism in the Lepidoptera. Heredity 10: 287–301. Majerus, M.E.N. 1998. Melanism: Evolution in Action. Oxford: Oxford University Press.

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Hof, A.E.v., Campagne, P., Rigden, D., C. J. Yung, J. Lingley, M. A. Quail, N. Hall, A. C. Darby & I. J. Saccheri. 2016. The industrial melanism mutation in British peppered moths is a transposable element. Nature 534: 102–105. doi:10.1038/nature17951

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