Why does evolution matter now answers

The first file is the question, answer these questions on the second file, the report.

Link for Lab Exercise 1: https://www.whfreeman.com/BrainHoney/Resource/6716/SitebuilderUploads/Hillis2e/Student%20Resources/Animated%20Tutorials/pol2e_at_1502_genetic_drift_simulation/pol2e_at_1502_genetic_drift_simulation.html#

Exercise 3 Video: Tuberculosis in Russia:

https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does-evolution-matter-now/

Exercise 4 Skull video:

https://www.youtube.com/watch?v=YGgDTQ3LnKI&feature=youtu.be

5 Lab: Evolution

Introduction

Life has existed on Earth for almost four billion years, and throughout this time, there has been a pattern of evolutionary change. Evolution is the change in the genetic makeup (heritable traits) of populations over time. Since the appearance of life on the early Earth, there has been a succession of life forms, with later species evolving from pre-existing species present on a younger Earth. The Earth provides many independent lines of evidence that point to a pattern of evolutionary change over time. This evidence comes from many sources – from the changes to the Earth itself, as living things altered the composition of the atmosphere and the land; from the fossil record, the remains and impressions of organisms from former geological ages; and from similarities in comparative anatomy, embryonic development, DNA, and proteins between living organisms. Living organisms are adapted to their environment. Adaptations take many forms, including behaviors, structures, biochemical pathways, and physiological modifications that increase the survival and reproductive success of an organism in its environment.

Exercise 1 Genetic Drift Simulation This is a virtual simulation provided by WH Freeman.

Introduction: Genetic drift is one of the mechanisms of evolution.

In this simulation, we look at changes in allele frequency. Remember that each individual has two alleles for an autosomal gene. Allele frequency refers to the frequency of a given allele (e.g. blue eyes) in the entire population. In a population with blue eye allele frequency of 0.5, blue and brown alleles are equally abundant, but less than 50% of the population will have blue eyes (due to many of the blue alleles existing in heterozygotes with brown eyes). An allele frequency of 0.0 means that the allele has gone “extinct” in the population (and will likely never exist again unless it is reintroduced from elsewhere), and a frequency of 1.0 means the other allele (e.g. brown eyes) has gone extinct. In either case, genetic diversity decreases as an allele disappears from the population.

Materials: Find the virtual laboratory exercise here:

https://www.whfreeman.com/BrainHoney/Resource/6716/SitebuilderUploads/Hillis2e/St udent%20Resources/Animated%20Tutorials/pol2e_at_1502_genetic_drift_simulation/p ol2e_at_1502_genetic_drift_simulation.html#

Procedure:

• Set the number of generations to 100. Leave the allele frequency at 0.5. • Start with population size 10.

https://www.whfreeman.com/BrainHoney/Resource/6716/SitebuilderUploads/Hillis2e/Student%20Resources/Animated%20Tutorials/pol2e_at_1502_genetic_drift_simulation/pol2e_at_1502_genetic_drift_simulation.html
https://www.whfreeman.com/BrainHoney/Resource/6716/SitebuilderUploads/Hillis2e/Student%20Resources/Animated%20Tutorials/pol2e_at_1502_genetic_drift_simulation/pol2e_at_1502_genetic_drift_simulation.html
https://www.whfreeman.com/BrainHoney/Resource/6716/SitebuilderUploads/Hillis2e/Student%20Resources/Animated%20Tutorials/pol2e_at_1502_genetic_drift_simulation/pol2e_at_1502_genetic_drift_simulation.html
BISC 100 – FIC Lab Week 5 2

• Press “plot”, and look at the results on the graph. 1. Does the allele frequency change significantly (more than about 0.5)? Is there a

clear trend in the allele frequency (increasing or decreasing)? Does the allele frequency become “fixed” (reach 0.0 or 1.0), and if so, in how many generations? Record the results in Table 1.

• Repeat this 5 times. • Repeat 5 times each for population sizes of 50, 100, 500, 1000 and 10,000

2. For the same population size, is there a consistent trend in allele frequency (does it

increase or decrease consistently)? 3. As population size increases, what happens to the effect of genetic drift (does the

allele frequency change significantly)? 4. As population size increases, what happens to the likelihood of an allele getting

fixed? Does the allele always become fixed at a given population size? If the allele is fixed, does it reach 0 or 1?

5. What can you conclude from these results about the nature of genetic drift?

Exercise 2 The Beak of Medium Ground Finch

In 1835, Darwin visited the Galapagos Islands, located about 900 km off the coast of Ecuador, South America. Although that distance is only a little farther than the distance between Vancouver and Calgary, there is deep water between the islands and the continental mainland, and the organisms that live on these remote islands are very different from their relatives on the mainland. Most of them are the descendents of a few individuals that were blown or carried to the islands.

Many new species have evolved from those few immigrants of long ago. Fourteen species of Galapagos finches have evolved from a single ancestral species of finches. We’re interested in the medium ground finch, a seed-eaters shown in Figure 2.1.

Figure 2.1. The medium ground finch

Scientists Peter and Rosemary Grant have been studying a population of medium ground finch on a tiny volcanic desert Galapagos island called Daphne Major. The ecological community of the island is simple, with only 40 species of plants. The Grants have visited this island for several months every single year for the last 35 years, bringing their two daughters along when the children were young. Now retired, the Grants still visit the island every year. They know every medium ground finch on Daphne Major. The birds are

BISC 100 – FIC Lab Week 5 3

tame and easy to capture or watch. Each year, the Grants track births, deaths, and mating and reproductive success of each bird. Beak size of medium ground finches vary, and that variation is heritable. Finches with deep beaks tend to have offspring with deep beaks.

Figure 2.2. Distribution of beak depth in 1976

Look at Figure 2.2, showing the range of beak depth in the medium ground finch population in 1976. Refer to this graph in answering the questions below.

6. What is the mean beak depth (red line in Figure 2.2)? 7. What is the range of beak depth?

In 1977, a little rain fell in January. Then a major drought set in. Instead of the normal rainfall of 130 mm per year, the total rainfall for 1977 was only 24 mm. Because of the drought, the island’s plants did not produce seeds in 1977. The seeds that the medium ground finches fed on were slowly depleted. In June 1976, there were 10 grams of seeds in every square meter of lava on the island. By June 1977, there were 6 grams per m2. By December 1977, there were only 3 grams of seeds per m2. The remaining seeds were large, hard Caltrop seeds, which are very hard to open. Only medium ground finches with beaks over 11 mm long can open Caltrop seeds. The Grants have never seen a finch with a beak less than 10.5 mm long even trying to open these seeds. In 1978, the rains returned to Daphne Major. When the Grants arrived for their field season, they found that there were only 90 medium ground finches left on the island. No new finches had hatched in 1977, and only a single finch born in 1976 had survived to 1978.

BISC 100 – FIC Lab Week 5 4

Figure 2.3. Change in distribution of beak depth from 1976-1978

Figure 2.3 shows the distribution in beak depth of finches before and after the drought.

8. What was the mean beak depth in 1978? 9. Did the finch population evolve from 1976 to 1978? Explain your answer.

The Grants saw natural selection producing evolutionary change in a single year, due to the effects of the drought and the selection for deep-beaked finches. Over a single year, the beaks got 0.54 mm deeper and 0.39 longer. Darwin thought that thousands of years would be needed to observe evolutionary change, but the Grants showed that a single drought could bring about evolutionary change in a population over a few months, as long as the conditions for natural selection are met in the population.

10. How does the change in beak depth fulfill the 3 conditions necessary for natural

selection? Provide evidence for each from the information provided above. We will assume that reproduction is almost always the case, so consider the other three conditions.

Condition#1

Condition #2

Condition #3

BISC 100 – FIC Lab Week 5 5

The careful observations and detailed measurements of beak depth made by the

Grants allowed them to see that evolutionary change can happen over very short periods of time on very small scales.

If you’d like to read more about this story, get a copy of Jonathan Weiner’s book The Beak of the Finch, the best book available on evolution by natural selection.

Exercise 3: Evolution of Antibiotic Resistance

Part A Simulation

Introduction

Antibiotic resistance is a growing public health issue. Antibiotics are used to treat barious bacterial infections, including tuberculosis (TB), a serious lung disease caused by the bacterium Myobacterium tuberculosis (MTB). This and other bacterial infections are typically treated with a variety of antibiotics, drugs that kill bacteria in a variety of ways. Improper use of antibiotics can promote increasing resistance to antibiotics (a genetic trait in MTB and other bacteria).

Any population of bacteria (e.g. the population of bacteria in the body) is likely to be relatively large (in the millions) and genetically diverse (due to high rates of reproduction and mutations). Some of those bacteria will have varying degrees of natural resistance to the antibiotic. When antibiotics are used, it is important to use them as indicated by the doctor in terms of the frequency of dosage and using the entire amount, even when you feel better. In this game, you will see why.

Although there are similarities, this is very different from the current situation with COVID- 19. COVID-19 is caused by a virus, a non-living intracellular parasite. Like bacteria it is very small (in fact much, much smaller than bacteria) and can be transmitted between people in some of the same ways. The similarities end there, however. The structure and behaviour of viruses is entirely different from bacteria. Antibiotics have absolutely no affect on viruses.

Materials:

• Make or find coloured disks or game pieces o 15 blue, 15 green, 15 red (or other colours or sizes you have available)

• A six-side die

Each piece represents 1 million bacteria: Blue = least resistant Green = Medium resistance Red = Highly resistant

BISC 100 – FIC Lab Week 5 6

Procedure:

• Start with 13 blue, 6 green, 1 red pieces.

• You have been prescribed an antibiotic to kill the bacteria. You need to take one pill each morning for 10 days.

Round 1 (as prescribed) I. On each turn, take the antibiotic as prescribed. Remove 5 blue pieces (= 5

million bacteria), then a maximum of 4 green pieces (only when there are no more blue left) and 3 red pieces (only when no green are left). Never remove more than 5 pieces on each “turn”. If removing more than one colour in a turn, remove the total amount of the lower resistance (e.g. if you have 2 green left, take away all the green and 2 red).

11. Fill in the results in table 1 in your lab report.

II. Overnight, remaining bacteria reproduce. Add one piece to the population for each colour remaining (e.g. if you finish the day with 0 blue, 3 green and 1 red you will add one green and one red).

III. Repeat steps I and II until all bacteria are gone (you continue taking the antibiotic for 10 days as instructed).

Round 2 (forgetful) IV. Roll the die:

▪ 2, 3, 4, or 5 = take the antibiotic. Remove pieces as described in step I above. ▪ 1 or 6 = You forgot to take the antibiotic. No bacteria are killed.

V. Follow steps II and II above, recording results in table 2.

12. Make a graph showing the % resistance over time for each of the four rounds. Use a different colour or style of line (dashes, dots, etc.) to indicate different trials, and include a legend. Label the axes, and provide a descriptive title. The dependent variable (see lesson 1) should be on the y (vertical) axis.

13. Imagine that you feel better (no symptoms) when the bacteria population is less than five million. However, you transmit your infection to another person. What is the possibility that person is infected with highly resistant bacteria (hint: look at your data on % resistance).

Round 3 (super-resistant) VI. A new strain of bacteria has evolved that is even more resistant to this

antibiotic. Repeat round 1 but this time the antibiotic kills 5 blue, but only 3 green or one red each time. After 10 days, stop using the antibiotic. Add your data to table 2 and your graph.

14. What happens in round 3?

BISC 100 – FIC Lab Week 5 7

Part B Tuberculosis in Russia

The following is from: PBS Learning Media (2001). Evolving Matters: Why does Evolution matter Now? Available from: https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does- evolution-matter-now/

Watch the video here:

https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas- why-does-evolution-matter-now/

Siberia once seemed impossibly remote. Not anymore. A drug-resistant strain of tuberculosis (TB) from a Siberian prison has been tracked to New York City. Using DNA fingerprints, microbiologists at the Public Health Research Institute in New York City have identified more than 12,000 different strains of TB from all over the world and are using this information to track the evolution of TB and its spread worldwide. But the strain they recently found in New York is different. It is one of the multi-drug-resistant strains from Russia that is very difficult to treat. Russian prisons have become breeding grounds for new multi-drug-resistant strains of TB because of crowded conditions, the use of low- quality antibiotics, and inadequate follow-up treatment for prisoners. At least 30,000 Russian inmates now have multi-drug-resistant TB.

A disease that had once been considered easily cured, TB has become a considerable enemy. TB is on the rise worldwide and now rivals AIDS in the number of lives it claims -- between 2 and 3 million each year. That's why microbiologists Barry Kreiswirth and Alex Goldfarb of the Public Health Research Institute are focusing on Russian prisons. Kreiswirth says, "What's dramatically affected the spread of TB is our ability to travel. All the strains that are in the Russian prisons will eventually come to our doorstep." To meet this challenge head-on, Goldfarb has developed a pilot program in the Siberian prison system to change the way that TB is treated, with the hope of preventing the evolution and spread of additional strains of multi-drug-resistant TB.

TB is only the tip of the iceberg. Use and misuse of antibiotics, especially in the United States, has spurred the evolution of drug-resistant forms of pneumonia, gonorrhea, and other infectious diseases. Kreiswirth laments, "We've created this problem. Multi-drug resistance is a manmade problem.... By developing as many antibiotics as we have over the last 50 years, we've essentially accelerated an evolutionary process. The outcome is that we're going to have more drug-resistant microbes to the point where some of the most dangerous bacteria will not be treatable. We're racing against the microbe every day, and unfortunately we're losing."

15. Describe how natural selection leads to TB drug resistance. 16. Sometimes patients stop taking the antibiotic when they feel better. How does this

increase the amount of drug-resistant bacteria in the population? 17. How does drug-resistance (as a genetic trait) arise in the first place? 18. The narrator in the video concludes, “Our very survival depends on an

understanding of evolution.” What do they mean by that?

https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does-evolution-matter-now/
https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does-evolution-matter-now/
https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does-evolution-matter-now/
https://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.whymatters/evolving-ideas-why-does-evolution-matter-now/
BISC 100 – FIC Lab Week 5 8

Antibiotic resistance goes well beyond tuberculosis. A variety of bacteria exhibit resistance, and normally minor infections become life-threatening if drug-resistant bacteria are responsible.

Antibiotics became widespread in the 1940’s. In the 1950’s many were available from pharmacies without a prescription. For decades, antibiotics were used for a wide variety of illnesses, even ones not caused by bacteria; this increased exposure to antibiotics has driven the evolution of antibiotic resistance. The first drug-resistant strains were identified by doctors in the 1950’s (Davies & Davies, 2010) and since then there has been an ever- expanding search for different antibiotics as existing treatments become less effective. Today, antibiotics are often used as a preventive measure in livestock (cows, chickens, etc.) and fish farms even as we understand that over-use of antibiotics is to blame for resistance. Some drug-resistant strains of bacteria require between 100 and 5,000 times the regular dose of antibiotic to be killed. Those doses as clearly impractical (imagine taking 1000 pills per day instead of one!) and likely toxic to the patient.

The World Health Organization (2018) identifies antibiotic resistance as one of the greatest threats to public health in the world. They recommend strict controls on antibiotic use, as well as greater emphasis on limiting disease transmission and non-antibiotic treatments. Some scientists recommend treatments, where necessary, that use a variety of antibiotics each for a short time, to prevent the development of resistance to any one drug. Others are considering bringing back old antibiotics (not used in decades) that today’s drug-resistant bacteria have never encountered.

Davies, J. & D. Davies (2010). Origins and Evolution of Antibiotic Resistance. Microbiology and Molecular Biology Reviews 74(3): 417-433 Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2937522/

World Health Organization (2018). Antibiotic Resistance. Available from: https://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2937522/
https://www.who.int/news-room/fact-sheets/detail/antibiotic-resistance
BISC 100 – FIC Lab Week 5 9

Exercise 4: Adaptive Radiation and Mammalian Dentition

Adaptive radiation is one of the major patterns of evolutionary change. It is the sudden (in evolutionary terms) diversification of a related group of organisms sharing a common ancestry. Adaptive radiation allows for new species to evolve. Adaptive radiation may result from the opening up of new ecological opportunities resulting from the mass extinction of existing species. Adaptive radiation may also result as organisms develop modifications of structure or physiology that allow them to exploit new environments. Adaptive radiation involves divergent evolution: different species arising through adaptive radiation are modified from a common ancestral form and physiology. Exercise 3: Adaptive radiation in mammalian dentition Most mammals have two sets of dentition (or teeth) in their lifetime. The first set is called the deciduous or milk teeth. The second is the permanent set. In addition, mammals possess heterodont dentition – literally, different kinds of teeth. These teeth include incisors, for biting or nibbling, canine teeth for tearing, and cheek teeth for chewing or grinding. Not all mammals possess all of these kinds of teeth. Variations occur as a result of adaptations to particular diets. Mammals arose from a common ancestor group. The earliest mammals were probably insectivorous. From this ancestor group arose a number of distinct feeding habits. Mammals have become adapted as herbivores, carnivores, and omnivores. With each feeding habit came adaptations of the dentition. Teeth that were not required for a particular mode of feeding were lost; other teeth became modified for greater efficiency in dealing with various foods. Watch the video posted on Moodle, then answer the following questions.

BISC 100 – FIC Lab Week 5 10

19. Identify the likely diet (herbivore, omnivore or carnivore) for each mammal shown below. Give at least three reasons for your choice in each case.

B

A

BISC 100 – FIC Lab Week 5 11

You can view more skulls in 3-D on the Digimorph website:

1. Go to http://www.digimorph.org/. 2. On the left side of the webpage, browse the library by common name or search for

your favourites. 3. To rotate the skull, select roll, pitch, or yaw under 3D Volume Rendered Movies on

the right side of the website.

20. Describe (with examples) how adaptive radiation has given rise to specialized dentition in mammals.

C

D

http://www.digimorph.org/