Biogeochemical cycles

In this module you have thought about populations, biogeochemical cycles, ecosystems, biomes, the importance of factual evidence, as well as climate change. You also approached viruses from the viewpoint of a nonliving to living interaction. In this final assignment, you will think like an informed citizen. The reintroduction of wolves has been a hot topic in mountain communities, but in your activity you will think about reintroduction of grizzly bears. It is a topic that has been discussed by national park rangers, citizens, wildlife groups, and even tourists. However, you should write your essay from the position of an informed citizen. Feel free to perform more research, as well as use the material provided to write your essay. The questions at the end of the reading passage will help you shape your essay. Welcome to the real world because, as a citizen, you will help make these decisions. It is up to you to make good ones.

You should spend approximately 2.5 hours on this assignment.

Instructions

  1. Read the case information.
  2. Using the questions at the end of the information as a guide, write an essay (300-500 words) on why or why not grizzly bears should be reintroduced to the Bitterroot ecosystem.
  3. Submit your essay to the Module 5 Assignment: Should Grizzly Bears Be Reintroduced Into the Bitterroot Ecosystem?

See the Course Schedule and Course Rubrics sections in the Syllabus module for due dates and grading information.

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“Th e Bear Facts” by Grace A. Wang Page 1

Background Few species have captured the imagination of the American public like the grizzly bear (Ursus arctos horribilis). It is one of the largest North American land mammals, with male grizzly bears often reaching 7 feet tall, weighing 300–600 pounds, and female grizzly bears 200–400 pounds. Th ey are an omnivorous species, with a diet that includes elk carcasses, sometimes sheep, berries, and whitebark pine seeds, among other items.

Although grizzly bears historically ranged throughout most of the western United States, habitat loss and excessive human-caused mortality have drastically reduced numbers of this species. It is estimated that prior to European settlement there were ~50,000 grizzly bears; it is estimated that only 800–1,000 grizzly bears exist on approximately 2 percent of their historic range in the lower 48 states now. Biologically, grizzly bears have the second slowest reproductive rate of all North American mammals, making it diffi cult for them to rebound from threats to their survival. Females reach maturity at 4–9 years, and generally give birth to two cubs every three years.

The Endangered Species Act Congress enacted the Endangered Species Act of 1973. Th e ESA declared national policy “that all Federal departments and agencies shall seek to conserve endangered species and threatened species and shall utilize their authorities in furtherance of the purposes of this [Act].” Th e ESA defi nes an endangered species as “any species which is in danger of extinction throughout all or a signifi cant portion of its range.” A threatened species is defi ned as “any species which is likely to become an endangered species within the foreseeable future throughout all or a signifi cant portion of its range.” Four key sections of the ESA provide its basic structure:

• A formal listing process used to identify threatened and endangered species, protect critical habitats, and the drafting of recovery plans.

• Federal agency consultation with the appropriate Secretary (Interior or Commerce) before taking any action that might aff ect a listed species.

• Prohibition of the “taking” of listed species and damage to their habitats. Th e term “take” means to “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct.”

• Penalties for violations of the ESA. Grizzly bears were listed as a threatened species in the lower 48 states in 1975. At that time, the Bitterroot Ecosystem (BE) was listed as one of three areas where grizzly bears were known or thought to exist and where recovery should be emphasized. Earlier in the 20th century, grizzly bears were widespread inhabitants of the Bitterroot Mountains in central Idaho and western Montana, although the last verifi ed death of a grizzly bear in the BE occurred in 1932 and

The Bear Facts: Grizzly Recovery in the Bitterroot Ecosystem by Grace A. Wang School of Forest Resources, The Pennsylvania State University

 

 

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“Th e Bear Facts” by Grace A. Wang Page 2

the last tracks were observed in 1946. No verifi ed tracks or sightings have been documented in more than 50 years, and the best scientifi c evidence available indicates that there are no grizzly bears in the BE at this time.

Figure 1. Map of Grizzly Bear Ecosystems in the northern Rocky Mountains.

Grizzly Bear ecosystems Bitterroot Ecosystem

The Recovery Plan In 1982, a federal grizzly bear recovery plan by the U.S. Fish & Wildlife Service (FWS) called for the evaluation of the BE as a potential recovery area. Ensuing studies indicated suffi cient habitat existed in the BE to support 200–400 grizzly bears. In 1991, the Interagency Grizzly Bear Committee endorsed the BE as a recovery area and authorized the FWS to pursue grizzly bear recovery. Th e ultimate long-term goal of the plan is removal of the grizzly bear from threatened status in the lower 48 states.

The Draft Environmental Impact Statement Th e FWS released a Draft Environmental Impact Statement (DEIS) in 1997, describing four alternatives that represent diff erent approaches to grizzly bear recovery and management in the Bitterroot Ecosystem of central Idaho and western Montana:

Alternative 1. Reintroduction of a Nonessential Experimental Population Alternative Section 10(j) of the Endangered Species Act provides the authority to designate certain populations of listed species as nonessential “experimental populations” to promote species conservation. Th is designation is more fl exibe than “endangered” and allows private landowners some fl exibility in dealing with reintroduced arenas. Th e goal of this alternative is to accomplish grizzly bear recovery by reintroducing grizzly bears designated as a nonessential experimental population to the Bitterroot Ecosystem. Central to this is creation of a Citizen Management Committee (CMC) to conduct grizzly bear management within the framework of local concerns. Th e CMC would be given the task of managing this grizzly bear population.

 

 

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“Th e Bear Facts” by Grace A. Wang Page 3

Alternative 2. The No Action Alternative—Natural Recovery Th e goal of this alternative is to allow grizzly bears to expand from their current range in north Idaho and northwestern Montana southward into central Idaho and western Montana, and to recolonize the BE. Ultimately, the goal is natural recovery of grizzly bears in the BE.

Alternative 3. The No Grizzly Bear Alternative Th e purpose of this alternative is to prevent grizzly bears from naturally re-establishing in the BE. Congress would need to pass legislation to remove grizzly bears in central Idaho and portions of western Montana from the list of threatened species. Th e FWS would stop all funding and management activity toward bear research, education, and management in central Idaho. Th e states of Idaho and Montana would remove grizzly bears from the protection of state law within the BE.

Alternative 4. Reintroduction of a Threatened Popula- tion with Full Protection of the ESA Th e goal of this alternative is to achieve recovery through reintroduction and extensive habitat protection and enhancement to promote natural recovery. Th e grizzly bear would have full status as a threatened species under the provisions of the ESA.

Th ese four alternatives represent diff erent approaches to grizzly bear recovery and management. Th ey were developed for evaluation in the DEIS because they encompass public concerns raised during scoping and to refl ect a full range of alternatives. Two alternatives (Alternatives 2 and 3) do not necessarily meet the purpose of and need for action, but were included in the DEIS to be responsive to public comments, to provide a full range of alternatives for consideration, and to meet the requirements of the National Environmental Policy Act (NEPA). NEPA ensures that environmental factors are weighted equally when compared to other factors in the decision making process undertaken by federal agencies. As part of this, NEPA requires that federal agencies prepare an environmental impact statement for projects they are requesting funding for from Congress. All four alternatives in the DEIS refl ect public comments and suggestions identifi ed through issue and alternative scoping.

Stakeholders / Public Concerns • Governor Phil Batt of Idaho and Senator Conrad Burns of Montana argue that grizzly reintroduction will lock

up the region’s timber reserves while jeopardizing the safety of constituents in the area: “Reintroduction will pose a signifi cant public safety risk for Idaho’s citizens, and many tourists who visit our wilderness areas.”

• Ravalli County Commissioner (Montana) Jerry Allen tells the federal government: “We don’t want the bears. I’m worried about the livestock and about the safety of my neighbors.”

• Some comments from other local citizens:

Figure 2. Grizzly Bear Recovery Alternatives in the Bitterroot Ecosystem.

 

 

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“Th e Bear Facts” by Grace A. Wang Page 4

“Grizzly bears attack people, and unlike the Fish & Wildlife Service, I do not believe there is an acceptable level of injury and death caused by grizzly bears.”

“We do not need our forests and other public lands shut down and put people out of jobs to encourage the grizzlies to roam into our backyards and endanger our lives.”

• Logging representative Jim Riley: “I don’t claim to speak for all loggers; but in general we are not afraid of living with grizzlies. What we fear most is having the federal government come in here and shut down traditional forms of resource extraction like logging to accommodate bears.”

• Th e environmental group Defenders of Wildlife supports reintroduction of the grizzly bears as an “experimental population,” and would like to set aside ~5,785 square miles of territory, allowing logging and grazing in the outlying areas. More signifi cantly, their plan allows for a team of “citizen managers” to voice local concerns. Hank Fischer of Defenders says: “Th is is a struggle between the purists and the pragmatists—and we’re the pragmatists. Any plan that puts people second to bears just isn’t going to fl y. If you don’t have the support of locals, these wildlife populations simply won’t survive.”

• Th e environmental group Alliance for the Wild Rockies champions a plan that would give full protection under the ESA, allowing federal biologists to manage reintroduction while keeping politics at bay. Th ey call for setting aside ~21,645 square miles of territory for reintroduction. Alliance executive director Mike Bader counters the Defenders plan: “Th e only thing that got compromised in [the Defenders] plan is the grizzly bear; introducing grizzlies without signifi cant habitat protection is like boarding them on a sinking ship.”

Questions 1. What are the major issues—economic, safety, animal rights, civil right—for each stakeholder group? 2. Are the opinions of local citizens more or less important than those of decisions makers in Washington D.C.?

Why or why not? 3. Given that reintroduction will occur on federal public lands, how important are the opinions of all citizens? Do

you think that non-local citizens should have a say in grizzly bear reintroduction? 4. How important are local fi nancial concerns in the decision to reintroduce grizzly bears? And which businesses

are most likely to benefi t or lose? 5. Taking all factors into consideration, which alternative truly benefi ts the grizzly bear population? 6. What are the ecological concerns related to grizzly bear reintroduction? 7. Which is more important in this case: the process or the outcome? 8. How might grizzly bear reintroduction aff ect the diff erent extractive industries (mining, timber, grazing)? 9. Why might diff erent environmental groups disagree?

References Blanchard, Bonnie M., and Richard R. Knight. “Biological Consequences of Relocating Grizzly Bears in the

Yellowstone Ecosystem.” Journal of Wildlife Management 59 (1995): 560–65. Eberhardt, L.L., and R.R. Knight. “How Many Grizzlies in Yellowstone?” Journal of Wildlife Management 60 (1996):

416–21. Fischer, Hank. “Bears and the Bitterroot.” Defenders Winter 1996/97:16+. Garshelis, David L. “Th e Grizzly Bears of Yellowstone: Th eir Ecology in the Yellowstone Ecosystem, 1959–1992.”

American Scientist January/February 1997: 72.

“Historic Plan Paves Way for Grizzlies’ Return to Idaho’s Bitterroot Region.” National Wildlife December/January 1996: 60+. “Montanans Learning to Live with Grizzly Bears.” Environmental News Network 29 September 1998:

http://www.enn.com/news/enn-stories/1998/09/092998/bears25.asp.

 

 

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

“Th e Bear Facts” by Grace A. Wang Page 5

Credits: Grizzly Bear from Summary of the Grizzly Bear Recovery Plan: U.S. Fish and Wildlife Service, 1993. Figures 1 and 2 redrawn by Jim Stamos (UB Dept. of Biological Sciences) from Chapter 2, fi gures 2–3 and 2–2 respectively, of the Grizzly Bear Recovery in the Bitterroot Ecosystem: Draft Environmental Impact Statement. Missoula, Montana: U.S. Fish and Wildlife Service, July 1997.

Case copyright held by the National Center for Case Study Teaching in Science, University at Buff alo, State University of New York. Originally published June 1, 1999. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

Oko, Dan. “Dispatches: Th e Debate Th at Roared.” Outside March 1998: http://outsideonline.com/outside/magazine/0398/9803dispwildlife.html.

Peacock, Doug. “Making the West Safe for Grizzlies.” Audubon November/December 1997: 46+. “Th e Possible Link.” http://www.defenders.org/defenders/grizgene.html. Quammen, David. “Island of the Bears.” Audubon March/April 1995: 82+.

“Grizzly Bear Reintroduction.” National Wildlife Federation: http://www.nwf.org/nwf/grizzly/index.html. Rembert, Tracey C., and Jim Motavalli. “Troubled Homecoming: Th rough Reintroduction Programs, Predators are

Returning to the Wild, Challenging our Expectations and Fears.” E March/April 1998: 28+. Robbins, Jim. “Scientists are Disputing the Fate of the Grizzly.” New York Times 23 June 1998: B12. Stevens, William K. “Debating Nature of Nature in Yellowstone.” New York Times 23 June 1998: B9+. United States. Department of the Interior. Fish and Wildlife Service. Grizzly Bear Recovery in the Bitterroot Ecosystem: Draft

Environmental Impact Statement. Missoula, Montana: U.S. Fish and Wildlife Service, July 1997. ___. ___. Fish and Wildlife Service. Grizzly Bear Recovery in the Bitterroot Ecosystem: Summary of the Draft

Environmental Impact Statement. Missoula, Montana: U.S. Fish and Wildlife Service, July 1997. Waller, John S., and Richard D. Mace. “Grizzly Bear Habitat Selection in the Swan Mountains, Montana.” Journal of

Wildlife Management 61 (1997): 1032–39. Wuethrich, Bernie. “Wayward Grizzlies Spark Debate.” Science 25 October 1996: 493. Young, Donald D., Jr., and Th omas R. McCabe. “Grizzly Bear Predation Rates on Caribou Calves in Northeastern

Alaska.” Journal of Wildlife Management 61 (1997): 1056–66. ___. “Grizzly Bears and Calving Caribou: What is the Relation with River Corridors?” Journal of Wildlife Management

62 (1998): 255–61.

•

 

 
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Biology Cell Discussion Board

BEFORE POSTING ANYTHING…..Read These Instructions! AttachmentCOLLAPSEOverall Rating:

Discussion Activity #1 Instructions (25 pts total)

For this discussion activity, I want you to use creativity and your understanding of cells and their structures to produce an original work that demonstrates your understanding of cells and their organelles and other cellular structures. Then, I want you to review each other’s original works and provide helpful feedback for improving the submission. Finally, you’ll revise your own work in response to your feedback, and then post the final version in your concluding post at the end of the week.

—————————————————————-
Prompt for your original essay post (12 pts), due by FRIDAY of the assigned week:

Before starting, choose to describe either a prokaryote (such as bacteria) or a eukaryote (such as an animal or plant cell) and make it clear in your post’s subject line which cell type you chose. Then, choose the TYPE of creative work you want to produce (see examples and suggestions below). Finally, make sure to include at least five (5) different organelles or sub-cellular structures in your original work as you create it.

Examples of creative/original works you could produce:

  • If you are an artist, create a work of art that tells the story of the cell you select in a drawing. As an artist, your work should be creative, not a tracing or copy of a figure from your book. Show us what YOU see.
  • If you are a musician or songwriter, compose a song about the cell you selected and type up the lyrics (and record yourself singing it as an audio file if you can).
  • If you are a poet, write a poem about your cell (not a haiku, please! that’s too short!)
  • If you want to be a teacher, create an activity that students could do to help them learn about the parts of the cell you chose and post the activity (post it without answers shown, but attach a file with the answers for students to look at after they’ve done it on their own).
  • If you like math, write about the relative dimensions of your cell and its component parts in relation to something we can visualize on a human scale. For example, if a cell were expanded to the size of a golf ball, how big would the nucleus be, then?
  • If you like politics and government, write an essay that uses a city as a metaphor for how a cell functions. What cellular structures/organelles could different parts of the city government and city services represent?

You don’t have to use one of these suggestions — be creative and come up with your own cell presentation!

Publish your original work as a NEW THREAD in this discussion forum. Please type a subject line that includes your cell type and creative title, then type/paste your original work directly into the text editor box so it shows up directly in the discussion board. Do NOT attach any files unless you created an audio or video file.

Here is an example of what a student in a previous semester submitted as his original work.  Yours does not need to be this great – I picked a really great example so you’d have an idea of how creative you could be. :)

—————————————————————-
Prompt for your response posts (4 pts each, 8 pts total), due by SATURDAY of the assigned week of discussion:

Read everyone’s posted original works and select at least TWO CLASSMATES for replies. Reply to these classmates, including the following elements:

  • A greeting (directed to the original writer) – i.e. say hello (preferably using their name).
  • A closing (sign off with your name) – i.e say a closing word (like “Regards” or “Great Job!” and then YOUR NAME (so they know how to address you if/when they respond to your feedback).
  • In between the greeting and closing: A response to what they wrote (in paragraph form with proper grammar/style) of at least 3-4 sentences providing:
    • at least one piece of positive feedback AND
    • at least one area where they could improve their original work.
  • Check grammar and spelling. This is a college-level course, so your writing should reflect that.
  • Follow the Netiquette rules provided in the “Getting Started” section of eCampus – be constructive, positive in tone, and helpful! Do not attack or insult!
  • I also want you to try to help everyone, so if a post already has a reply, find a different post to reply to if you can.

—————————————————————-
Prompt for your SUMMARY / CONCLUDING post (5 pts), due on SUNDAY of the assigned week of discussion:

Review all of the original and response posts, then EDIT/IMPROVE your original work based on the feedback and anything you wanted to add. Even if you did not receive any replies or suggestions, you still need to make at least one improvement to your original submission and post the final version in its entirety along with a brief description of what you changed. To post your conclusion, make sure to select the “reply” to YOUR original post so it is nested in the correct location on the forum. Do NOT create a new thread for the conclusion.

Do NOT write your conclusion and final version until after Saturday night so all your classmates have time to respond and provide feedback to you by the reply deadline. Posting your conclusion too early will result in lost points.

A grading rubric will be used to calculate your grade on this discussion.  You are welcome to review the rubric to see how I will determine your score BEFORE you write your posts. A copy of the rubric is available in the grade book (in the Discussion Activity grade information).

Do NOT reply to this thread. Return to the main forum page and create a new thread for your original post.

 
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ANT 3514C – Introduction To Biological Anthropology Lab 3: Forces Of Evolution

me: ________________________________________ Section: ___________

ANT 3514C – Introduction to Biological Anthropology

Lab 3: Forces of Evolution

Purpose: To illustrate how multiple forces of evolution act on populations through time.

Learning Objectives:

· Define the driving forces of evolution and identify their effects at the population level

· Understand the necessary conditions of evolutionary (Hardy-Weinberg) equilibrium

· Predict how different forces of evolution influence diversity within a population through time

Lab Activity: Population Genetics & Evolutionary Forces Simulation

The “Modern Synthesis” was a term coined in 1942 by Julian Huxley in a book of the same name. Huxley used the phrase to summarize the tremendous explosion of biological theory and research that began to occur in the 1930’s as Darwin’s theory of Natural Selection was merged with Mendelian principles of heredity. The synthesis is represented by a series of collaborative seminal works from scientists who have since become legends: geneticists such as Haldane, Dobzhansky, and Wright, mathematicians such as Fisher, taxonomists such as Mayr, and paleontologists such as Simpson. At that time, their publications laid the foundation for the basic theories of evolution that are still accepted and applied today, and prompted the famous precept by Theodosius Dobzhansky that “Nothing in biology makes sense except in the light of evolution.”

In the previous lab, we discussed the basic principles of genetic inheritance of traits for individuals. This week’s lab will expand upon your understanding of how genetics works at the population level. In the following exercises, we will do a group activity and use a computer simulation to evaluate the effects of evolutionary forces on populations over multiple generations.

In the context of population genetics, evolution is defined as a change in allele frequency in the gene pool of a population over time. Alleles are separate copies of genes. In most cases, each individual has 2 alleles for every gene, which are known together as the genotype. Evolution is only possible if there is variation in these alleles within a population. Since different alleles may have different effects on the body or behavior of an organism (the organism’s phenotype), changes in the frequencies of alleles can result in phenotypic changes of a population. Certain alleles may be selected out through time or disappear by chance, while others may become more commonplace. Changes in allele frequencies within populations are thought to be responsible for most major patterns of evolutionary change, when magnified by the accumulation of time over many generations.

The Hardy-Weinberg equilibrium is a theoretical model that states that allele frequency and genotype frequency (and by extension, phenotype frequency) will remain constant in a single population that is not subject to the forces of evolution. This model allows us to test how changes in any of these variables would influence the other variables.

The conditions of Hardy-Weinberg equilibrium are:

1. No mutation

2. No migration (gene flow)

3. No selection (all genes/traits equally viable)

4. Random mating is equally likely among all members of the population

5. Large population

Forces of Evolution

Modern evolutionary biologists recognize that four primary forces of microevolution can alter allele frequencies within populations. These include:

1. Mutation – the spontaneous change of one allele into another

2. Gene Flow – a.k.a. migration, the influx/outflow of alleles from/to other populations

3. Genetic Drift – the reduction of allele diversity via random chance (such as genetic bottlenecks and the founder effect)

· Genetic Bottleneck = sudden reduction in population size (e.g., due to natural disasters)

· Founder Effect = a small, random sample of a larger population breaks off to establish a new population (for instance, a small group from the mainland colonizes an island)

4. Selection – a.k.a. natural selection as proposed by Darwin. Conditions of the environment (physical, social, etc.) cause nonrandom elimination of some individuals’ alleles in the next generation, either because they were unable to successfully reproduce, or had no offspring that were able to successfully reproduce.

Exercise 1: Population Genetics (2 pts)

You come upon a tribe of humans that was previously undiscovered. The tribe is called Bretep. It has approximately 30 members and is governed by one chief, Chief Sakon. In the midst of learning everything you can about the groups culture and behavior, you gather some information on the evolutionary history of the group. Chief Sakon tells you that his second son, Ulan, will become the next chief because his first born, Lyzij, decided to leave the tribe and create his own group about 10 years ago. Lyzij took a small subset of the original tribe with him when he left. Chief Sakon hasn’t heard from him since and hopes he is doing well.

1. By leaving the original tribe, Lyzij’s group will be genetically affected by a _____________________ [evolutionary force]. How will the gene pool of this new group likely compare to the gene pool of the original tribe? Why do you expect that? (.75 pts)

You ask Chief Sakon if losing those members of his tribe has hurt the dynamics of the group. He describes a period of time in which the group struggled because their best potters when with Lyzij. However, the past few years have been fine because they found another tribe that was willing to trade goods with them. They meet often and even regularly choose members from this tribe to marry and bring into the Bretep. You are told that Ulan’s wife was originally from this other tribe. Chief Sakon very happily informs you that they have had many strong, healthy children that will help the Bretep prosper in the future.

2. What evolutionary force is acting on the Bretep when they intermarry and reproduce with the other tribe? Will this increase or decrease the genetic diversity of the Bretep? Why? (.75 pts)

Exercise 2: Computer simulation, Evolutionary Forces

(Adapted from: Dr. Jonathan M. Brown, Grinnell College)

About the simulation program – Red Lynx is a browser-based population genetics simulator developed by Reed A. Cartwright, an evolutionary biologist at Arizona State University. It can be accessed at http://scit.us/redlynx/. Once the webpage has loaded, click “Start Red Lynx Simulator” to start the program.

Red Lynx allows you to investigate how the four evolutionary forces affect allele frequency over many generations. In this case, our allele of interest is called “A1”. Once the web page has been started, adjust the number of generations to 1000 (type it into the corresponding box to be exact), and run a number of simulations. If you select the “Help” hyperlink, descriptions for each variable will be displayed. You should see a variety of different outcomes in the frequency of A1. For the most part, the frequency will fluctuate through time, but A1 will still be present in the population – though in rare instances A1 will become either fixed (frequency = 100%) or completely lost (0%).

Getting started:

▪ Press “Clear Graph” and adjust the generations to 1000 by typing the number into the adjacent box.

▪ Play with the existing settings until your simulated population reaches Hardy-Weinberg equilibrium, in which no further evolution is occurring.

1. What happens to the allele frequency in the population once Hardy-Weinberg equilibrium is achieved? (0.5 pts)

2. What adjustments had to be made to the population size? How did changing the population size affect allele frequency equilibrium? (1 pts)

3. Once the population is in Hardy-Weinberg equilibrium, how does the allele frequency change if the initial frequency is adjusted? (0.5 pts)

4. Is Hardy-Weinberg likely to exist in nature? Why or why not? (0.5 pts)

5. Refresh the page and restart Red Lynx to return to the original settings. Mutations are the only source of novel genetic material in biological organisms. The average mutation rate among humans is 2.5e-8 per base per generation (very low!). Type this number into the box for A2 Ă  A1 Mutation Rate.

▪ Be sure the population is set to 800 and the graph is clear.

▪ Set the number of generations to 10 (roughly 200 – 300 years for humans) and run 10 simulations.

What happened to the allele frequency? (0.25 pts)

6. Clear the graph, change the number of generations to 100, and run the simulation 10 times.

▪ Repeat the above instructions with 1000 generations (roughly 20,000 – 30,000 years).

What is happening as time increases? (0.5 pts)

7. What does this tell us about the effect of mutation alone on evolution? (0.5 pts)

8. Keeping the population size at 800 and the mutation rate at 2.5e-8, we will look at the effect of migration.

▪ Set the migration rate to 5% and the migrant allele frequency to 25%

▪ Change generations to 100, clear the graph, and run 5 simulations.

What happens to the allele frequency over time? (0.25 pts)

9. Is the overall variation within the population increasing or decreasing? (0.5 pts)

10. Clear the graph.

▪ Now we will investigate the effects of positive and negative selection. Return the migration rate to 0%.

▪ Set the selection strength to 0.006 and run 10 simulations.

What do you observe? Is the overall variation within the population increasing or

decreasing? (0.5 pts)

11. Now set the selection strength to -0.006 and run 10 simulations. How do the results differ from those in the previous 10 simulations? (0.5 pts)

12. Which one of these two selection scenarios would be more common in nature? Hint: are mutations that have an effect on the phenotype usually beneficial or harmful? Why? (0.5 pts)

READING ASSIGNMENT (2 pts): Stock, Jay, T. 2008. Are humans still evolving? EMBO reports Special Issues 9: S51-S54.

Remember that plagiarism will not be tolerated and may result in a score of 0 for the entire lab. If employing a phrase from the reading or elsewhere, you must place it in quotations!

1. Why do humans show less genetic diversity than other species? (.5 pts)

2. Provide two examples of recent human evolution from the article. (.5 pts)

3. Describe what ways animals can respond to environmental stress other than genetic adaptation? What possible future environmental stresses does the author predict? (1 pt)

4 years ago

 
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Evolution of Genes and Culture

LESSON

 

 

evolution of Genes and Culture

 

 

 

 

LESSON

 

STUDENT MATERIALS

 

The Making of the Fittest:

 

Got Lactase? The Co

evolution of Genes and Culture

 

 

 

 

LESSON

 

STUDENT MATERIALS

 

The Making of the Fittest:

 

Got Lactase? The Co

evolution of Genes and Culture

 

 

 

The Making of the Fittest: Natural

GOT LACTASE? BLOOD GLUCOSE DATA ANALYSIS

INTRODUCTION

“Mother’s milk” is packed with the proteins, fats, and carbohydrates that support the growth, development, and survival of baby mammals. The sugar lactose is the main carbohydrate in milk. Lactose can be cleaved into two simpler sugars, glucose and galactose, by lactase, an enzyme produced in the small intestine. The two smaller sugars are readily absorbed though the intestinal wall into the bloodstream for delivery to the cells of the body, where they are used for energy.

 

 

After infant mammals are weaned from their mother’s milk, lactase production shuts down, presumably because it is no longer needed. This condition is called lactase nonpersistence—meaning that production of the lactase enzyme does not persist into adulthood. The general condition for mammals is not to consume milk after weaning and to be lactase nonpersistent. Some populations of humans are unusual in that adults continue to consume milk from other mammals, such as cows.

If a person who is lactase nonpersistent drinks milk, undigested lactose passes from the small intestine to the large intestine, where it is fermented by bacteria. Fermentation produces various gases in the large intestine, which can cause abdominal pain, bloating, flatulence, and diarrhea—all symptoms of lactose intolerance. Worldwide, most adults are lactose intolerant, although some people may not know it because their symptoms are mild. Only a minority of human adults (about 35% of the global human population) continues to produce lactase into adulthood and can drink milk without any problems. These individuals are said to be lactase persistent or lactose tolerant.

There are several ways to test whether someone is lactase persistent. In the short film, Got Lactase? The Co-evolution of Genes and Culture, the narrator, Dr. Spencer Wells, takes a blood glucose test to deduce his lactase status. In this activity you will examine the results of blood glucose tests conducted on six different adults to determine who is lactase persistent (lactose tolerant) or lactase nonpersistent (lactose intolerant).

MATERIALS

· Ruler

· Colored pencils

 

 

 

 

Got Lactase? Blood Glucose Data Analysis

Updated November 2014

 

 

 

 

 

www.BioInteractive.org

 

 

 

 

 

 

 

 

 

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PROCEDURE

1. Examine the data in the table below. It shows the blood glucose levels of six individuals tested in Dr. Sarah Tishkoff’s laboratory. After baseline (i.e., time 0 minutes) blood glucose levels were measured and recorded, each person drank a liter of milk. Blood glucose levels were again measured at 15, 30, 45, and 60 minutes after drinking the milk. Glucose levels were measured using glucose strips and a glucose reader similar to the one Dr. Wells used in the film.

 

  Blood Glucose (mg/dL)      
Individual 0 minutes 15 minutes 30 minutes 45 minutes 60 minutes
Spencer Wells 117 128 146 160 152
Peter 97 111 135 154 143
Rachel 96 99 105 101 98
Katherine 95 97 99 101 102
Sarah 108 116 129 141 139
Michael 94 109 128 143 140
Arthur 97 96 94 83 88

 

2. Plot the results from the six individuals in the graph below. The graph already includes Dr. Wells’ blood glucose test results. Make sure to include a legend for your graph.

 

Lactase Persistence Blood Glucose Test Results

 

80

90

100

110

120

130

140

150

160

0

10

20

30

40

50

60

Blood Glucose (mg/dL)

 

Time (minutes)

Spencer Wells

 

 

3. After graphing the data, answer the questions below.

QUESTIONS

1. Why is measuring blood glucose levels an indicator of someone’s lactase activity?

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2. Divide these individuals into two groups (A and B), based on their blood glucose test results. Write the names of the individuals in each group, including Dr. Spencer Wells.

Group A:

 

Group B:

 

3. Explain your rationale for dividing the individuals into these two groups using data to support your answer.

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4. Based on these data, do you predict that individuals in Group A are lactase persistent or nonpersistent? Describe the evidence that supports this claim.

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5. Based on these data, do you predict that individuals in Group B are lactase persistent or nonpersistent? Describe the evidence that supports this claim.

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6. If you performed the same blood glucose test on a group of people who are from the Maasai population in Kenya, predict whether their results would be more like those of Group A or Group B. Explain your prediction.

(Hint: Remember from the film that the Maasai people are pastoralists.)

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7. A person taking a blood glucose test is usually told to fast prior to the test. Why do you think that might be necessary?

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