How is vitamin d linked to natural selection

how is vitamin d linked to natural selection

Using the Pdf attached, refer to page 33-42 and briefly answer the following questions. just about 3 pages

1. What are the causes of skin cancer?

2. Why are Caucasians more at risk of skin cancer than other populations?

3. At what age does skin cancer typically occur? Is the incidence of skin cancer greater in youth or old age?

4. Does the amount of UV light reaching the Earth vary in a predictable manner (Figure 6-3)? If so, describe the pattern you observe.

5. What latitude receives the greatest amount of UV light (Figure 6-3)? The least?

6. Based on these data (Figure 6-3), where might you expect to find the most lightly pigmented and most darkly pigmented people on the planet? Be as specific as you can.

7. Provide a rationale to your answer above (i.e., why did you think that more darkly pigmented people would be found in those areas)?

8. Interpret Figure 6-4 and the trend it describes.

A. Is skin reflectance randomly distributed throughout the globe? If not, how would you describe the pattern?

B. Restate your findings in terms of skin color and UV light (instead of skin reflectance and latitude).

C. How closely do these findings match the predictions of your hypothesis (Question 6)?

D. Some populations have skin colors that are darker or lighter than predicted based on their loca­tion. Their data point falls somewhere outside of the line shown in (Figure 6-4). What might ex­plain the skin color of these exceptional populations? Propose a few hypotheses.

E. Hypothesize why different skin colors have evolved.

9. Hypothesize why different skin colors have evolved. Based on what you know, what factor is most likely to exert a selective pressure on skin color?

10. Review your answer to Question 3. Keeping your answer in mind, how strong a selective pressure do you expect skin cancer (UV-induced mutations) to exert on reproductive success?

11. Based on this information, does your hypothesis about the evolution of skin color (Question 9) seem likely? Why or why not? How does skin color meet, or fail to meet, the three requirements of natural selection outlined above?

12. Based on Branda and Eaton’s results (Figure 6-5), what is the apparent effect of UV light exposure on blood folate levels?

13. What is the apparent effect of UV light on folate levels in these test tubes? __________________

14. How is folate linked to natural selection?

15. All other things being equal, which skin tone would you expect to be correlated with higher levels of folate? _________________________________________________________________________

16. Based on this new information, revise your hypothesis to explain the evolution of human skin color.

17. What would happen to the reproductive success of:

A.light-skinnedperson living in the tropics? _________________________________________

B. light-skinned person living in the polar region? _____________________________________

C.dark-skinned person living in the tropics? _________________________________________

D. dark-skinned person living in the polar region? _____________________________________

18. Predict the skin tones expected at different latitudes, taking folate needs into consideration. Use the world map (Figure 6-6) to indicate the skin tone expected at each latitude (shade the areas where populations are darkly pigmented).

19. Can folate explain the variation and distribution of light- and dark-skinned individuals around the world?

20. How is vitamin D linked to natural selection?

21. Which skin tone allows someone to maintain the recommended level of vitamin D? ________________

22. Based on this new information, revise your hypothesis to explain the evolution of the variation and distribution of human skin color.

23. Taking only vitamin D into consideration, what would happen to the reproductive success of:

A. light-skinned person living in the tropics? _________________________________________

B. light-skinned person living in the polar region? _____________________________________

C. dark-skinned person living in the tropics? _________________________________________

D. dark-skinned person living in the polar region? _____________________________________

24. Predict the skin tones expected at different latitudes, taking only vitamin D needs into consider­ation. Use the world map (Figure 6-8) to indicate the skin tone expected at each latitude (shade a region to represent pigmented skin in that population).

25. Can vitamin D alone explain the current world distribution of skin color? ____________________

26. Using principles of natural selection, predict the skin tone expected at different latitudes, taking ul­traviolet exposure, vitamin D, and folate needs into consideration. Use the map (Figure 6-9) to indicate skin tone patterns at different latitudes (shade regions where populations are expected to be darkly pigmented).

27. Are UV light, vitamin D and folate needs sufficient to explain the current world distribution of skin color? ___________________________________________________________________________

28. How might you explain that Inuits, living at northern latitudes, are relatively dark-skinned (much more so than expected for their latitude)? Propose a hypothesis.

29. Conversely, Northern Europeans are slightly lighter-skinned than expected for their latitude. Pro­pose a hypothesis to explain this observation.

Concepts in Biology Laboratory

Biol 1100L

Spring 2014

Please note that this manual is a work in progress and was compiled specifically for the ISU Biology department. It changes each semester/session depending on the interests of the instructors. It is

a free and unpublished manual that has not seen reviewers or editors; there are errors.

The first step in the acquisition of wisdom is silence, the second listening, the third memory, the fourth practice,

the fifth teaching others.

~Solomon ibn Gabirol (1021 -1058 AD)

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Biol 1100L Ecology1 Lab 1

1. Define hypothesis using your textbook.

Name:_______________________________ Section:____

In lab this week you will gather observational data about arthropod distributions and ecol- ogy, describe their niches in terrariums, construct a hypothesis, make a prediction, and calculate the diversity (Shannon-Weiner Diversity Index) for each niche type. Arthropods are a major component of all terrestrial ecosystems and their behavior has been the object of many famous ecological studies. All arthropod species are in the Kingdom Animalia and Phylum Arthropoda but they are in many different classes, orders, and families. A large proportion of arthropods are plant detritivores, i.e. organisms that feed on dead and decaying plant material. These organisms hasten the conversion of biomass to soil, speed up rates of nutrient cycling, and as a result, increase the productivity of ecosys- tems. In this lab you will learn about three very important ecological concepts: diversity, niche and the competitive exclusion principle. Diversity can be measured in a number of different ways, and you will use the Shannon-Weiner Diversity Index. The niche is a set of environ- mental factors necessary to the continued existence of a species. The niche describes anything you might be able to think of that an organism requires. This includes what it eats, where it eats, when it eats, when it sleeps etc. The competitive exclusion principle states that two species with identical niches cannot coexist indefinitely (Gausse 1934). It makes sense that species that coexist will have different niches. If they didn’t they would either be in the process of going extinct or driving their competitor into extinction. The way species subdivide niche space has been called niche partitioning.

Figure 1-1. Diagram of an arthropod terrarium.

Part 1. Defining Niches

One of the members of your group will obtain a terrarium and poking / digging tools from the west end of the lab. Do not do anything to the terrarium yet. Note the overall structure of the terrarium ecosystem (Fig. 1-1). As a group talk about the different ways the species of arthropods could partition this niche space to avoid identical niches. Be prepared to present your group ideas to the class. Decide as a class on 4 distinct niches that would be good to use. All groups of students must use the same niches to continue with the exercise.

2. What is an example of a hypothesis (see textbook)?

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Biol 1100L Ecology1 Lab 1

3. What are the niches you and your classmates identified for the terrarium? 1___________________ 2___________________ 3___________________ 4___________________

4. As a class construct a hypothesis about arthropod abundance and diversity of each niche.

Table 1-1. Abundance of arthropod types from ter- rarium #_____.

Arthropod Niche

1 2 3 4 cricket isopod millipede bess beetle tenebrio beetle other 1 other 2 Total Abundance

5. As class make a prediction about arthropod abundance and diversity of each niche.

Part 2. Data Collection

Observe your terrarium. Carefully, without disturbing the other niches, search one niche for arthropods. Be gentle and care-

ful (we don’t want to harm any of the arthropods). As you find an arthropod place it in the plastic holding chamber.

6. Fill in the appropriate niche/arthropod cell in Table 1-1 with count data using tick marks. NOTE: do not count dead arthropods.

Repeat for all the niches.

Part 3. Data Analysis

To calculate diversity biologists use indices that are based on mathematical equations. For this lab you will use the diversity spreadsheet linked to Moodle to calculate the Shannon-Wiener Index (H’) which is calculated as -Σ(pi ln pi). This index is an indicator of the evenness and richness (i.e. number of arthropod species and the abundance within each species) within an environment. H’ ranges upwards from 0. The 0 value indicates a single species and increases as richness and evenness increases. When you have completed your observations, each group will provide their niche totals from Table 1-1 to the class.

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Biol 1100L Ecology1 Lab 1

7. Calculate a class average using the Excel spreadsheet linked to Moodle for each arthro- pod type in each niche and enter that average into Table 1-2.

8. Using the class averages, cal- culate Shannon- Wiener Diver- sity Index (H’) for each niche using the Ex- cel spreadsheet provided and fill in Table 1-3.

Table 1-2. Average abundance of arthropod types from all terrariums studied.

Arthropod Niche

1 2 3 4 cricket isopod millipede bess beetle tenebrio beetle other 1 other 2 Total Average Abundance

Table 1-3. Shannon-Wiener Diversity Index (H’) for each niche.

Niche H’ 1 2 3 4

9. In a complete sentence and in your own words define the Shannon-Wiener Index (H’). What two important factors are taken into account by the Shannon-Wiener Diversity Index?

10. Did you conclude that your prediction was true or false for the diversity of arthropods per niche?

11. Did you accept or reject your hypothesis?

12. In retrospect would you have modified your selection/distinction of niches?

13. Did the taxonomic descriptions in the appendix appear to agree with the niches you saw the arthro- pods in?

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Biol 1100L Ecology1 Lab 1

Cricket Class: Insecta Order: Orthoptera Family: Gryllidae

Bess Beetle Class: Insecta Order: Coleoptera Family: Passalidae

Darkling Beetle Class: Insecta Order: Coleoptera Family: Tenebrionidae

Isopod (Pill bug) Class: Malacostraca Order: Isopoda Family: Armadillidiidae and Porcellionidae

Millipede Class: Diplopoda Order: Spirobolida Family: Spirobolidea

This group of insects is closely related to grasshoppers that are in the Family Acrididae. Most species of crickets overwinter as eggs. All crickets have auditory organs on their front tibia. The male cricket rubs its wings together to make a chirping sound. The young cricket, or nymph, looks like an adult except that it is smaller and not sexu- ally developed. Crickets are generally scavengers that will eat essentially anything.

These are large (32-36 mm long) shiny black beetles. The mouth is adapted for chewing wood. Passalids are somewhat social and their colonies live in decaying logs. The adults can produce a squeaking sound by rapidly rubbing their third legs against their fifth abdominal sec- tion. All beetles undergo larval and pupal stages before emerging as adults.

These dark brown flying beetles are also known as dark- ling beetles. Most tenebrionids feed on plant matter of some kind and often live in cornmeal, dog food, cere- als, and dried fruits. The Tenebrionidae is the fifth larg- est family of beetles with over 1000 species in North America.

These organisms are actually crustaceans and are closely related to crabs and lobsters. The name isopod literally means equal-legs. Individuals in this group are often found under boards and decaying wood. They eat wood and logs as they decay. Isopods breathe with gills so they must live in an area that is constantly moist.

Millipedes are elongate wormlike animals with many legs. Most millipedes have 30 or more pairs of legs. They tend to avoid light since they have eyespots on their heads that are sensitive to light. They live on dead leaves or other decaying material.

14. Do you feel you have made an adequate description of niche space of these arthropods? Why or why not?

15. Which niche was most diverse? Why do you think this is the case?

2-1

Biol 1100L Population Ecology Lab 2

Name:_______________________________ Section:____

Part 1. Population Study

A summary of mortality, survivorship, and ex- pectation of further life by age, is called a life table. The most straight forward type of life ta- ble starts with a cohort of young organisms and follows their fortunes through their lives, until the last one dies. Because cohort data are usu- ally difficult to obtain, most life tables are calcu- lated using other kinds of information. If we can obtain mortality rates by age of a population we can, after the appropriate assumptions and cal- culations, construct a life table (called a time- specific table, versus the age-specific cohort table). A frequent approach, and the one used here, is to use age at death to estimate mortal- ity rates and calculate the other vital statistics from that. Tables produced in this way are age- specific, even though the cohort is composite, made up of individuals that started life in differ- ent years. The study of human populations is called de- mography and is a branch of science called population ecology. A population is defined as a species (interbreeding individuals) within a de- fined area. In this lab, we will be exploring the Idaho Falls population. Using the data that was collected from the Rose Hill Cemetery of Idaho

Table 2-1. Life table of the Idaho Falls population pre-1930 and post-1970. Where x is the beginning age of the age class, nx is the number alive (survivors) at age x, lx is the proportion of survivors at age x, dx is the number dying (mortality )within the age class x, and qx is the mortality rate (that is, dx/nx).

Table 2-2. Data collected from the Idaho Falls Rose Hills Cemetery during Spring 2010. Also known as mortality (dx) pre-1930 and post-1970 of the Idaho Falls popula- tion.

Falls (Table 2-1), the life table (Table 2-2), and the survivorship curves (Fig. 2-1) constructed you will answer a few questions.

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Biol 1100L Population Ecology Lab 2

1. Look at circle A on Figure 2-1. Why do you think there is a steep decrease in survivorship for the pre-1930 population?

2. Comparing pre-1930 and post-1970 populations, has the proportion of people surviving through an age class increased or decreased for the Idaho Falls population (excluding the last two age classes)?

3. What has changed since pre-1930 to make an increase in survivorship possible?

4. Do you think this is similar for the entire US population?

Figure 2-1. Proportion (as a percentage) of survivors (lx) at age x of the Idaho Falls population pre-1930 and post-1970.

A

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Biol 1100L Population Ecology Lab 2

Part 2. Ecological Footprint

Lifestyle in advanced nations like the US depends significantly on the direct or indirect burning of fossil fuels. Many people in less developed nations, however, do not depend on large-scaled burning of fossil fuels. Imagine a subsistence farmer in an undeveloped country living in a mud hut without electricity or running water. The family is fed from the small herd of animals and crops adjacent to its dwelling. The family does not own a car, and travel to the next village requires an ox and a cart. The family does not own any electrical appliances or electronic media. Consider another family in a more developed part of the world but less developed than North America or Western Europe. The family has electricity in its small home, but it does not own a car and has just bought its first TV. The father rides his bike to a nearby village for work. The mother walks to the local village market three times a week for local produce and meat. The atmospheric CO2 level was approximately 280 parts per million (ppm) before the industrial revolu- tion and is now 393 ppm (in 2005 it was 387 ppm). A greenhouse gas, CO2, is emitted from a variety of sources, many of them associated with the burning of fossil fuels. For example, when you drive a car, the exhaust emissions include CO2. When you heat or cool your home the required energy often comes from the burning of fossil fuels in power stations. But have you ever stopped to think that your diet may play a role in CO2 emissions? If you eat meat and shop for it at a supermarket chain, there is strong chance that the source of your T-bone steak is a distant slaughterhouse. In winter, the lettuce that makes up the bulk of the salad you eat may be shipped from tropical locations. Your steak and lettuce than travel by truck to reach your supermarket delicatessen or produce counter, contributing to CO2 emissions along the way. In 2007 the biosphere had 11.9 billion hectares of biologically productive space corresponding to roughly one quarter of the planet’s surface. These 11.9 billion hectares of biologically productive space include 2.4 billion hectares of ocean and inland water and 9.1 billion hectares of land. The land space is composed of 1.6 billion hectares of cropland, 3.4 billion hectares of grazing land, 3.9 billion hectares of forest land, and 0.3 billion hectares of built-up land.

One of the ways that you can visualize your own personal impact on the ecology of the planet is to calculate your Ecological Footprint. In this activity you will use the Global Footprint Network to determine your Ecological Footprint.

5. Use the Global Footprint Network glossary to define the following; 1) gha, 2) biological capacity (biocapacity), 3) biological capacity per person, and 4) ecological footprint.

http://www.footprintnetwork.org/en/index.php/GFN/

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Biol 1100L Population Ecology Lab 2

6. What kinds of behavior reduce Ecological Footprints?

7. Use the Global Footprint Network website to calculate your footprint. You must enter “Detailed Information”. Fill in Table 2-3.

Table 2-3. Your Ecological Footprint. http://www.footprintnetwork.org/en/index.php/GFN/page/calculators/

Food Shelter Mobility Goods Services Planets GHA Carbon Dioxide

8. Look at Figure 2-2 A and B: A. What is the biocapacity per person for the USA? B. What is the Ecological Footprint of consumption for the USA. C. How do these numbers compare to the majority of the world?

10. Look at Figure 2-2 D and E: A. Is the USA a creditor or debtor nation? B. What is the USA’s Ecological Footprint percentage over domestic biocapacity? C. What is the USA’s Ecological Footprint percentage over globally available biocapacity? D. How do these numbers compare to the rest of the world? E. How can the USA become a creditor nation if our domestic consumption is 8 gha per person

but our domestic biocapacity is 3.87 gha per person and the global biocapacity is 1.78 gha per person?

9. How does the USA’s Ecological Footprint of consumption (Figure 2-2 B) compare to Ecological Footprint of production (Figure 2-2 C) and how does this compare to the majority of the world?

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Biol 1100L Population Ecology Lab 2

11. Look at Figure 2-2 F: A. Is the USA a net importing or exporting country?

B. How many gha do we import each year? C. Could the USA Ecological Footprint be reduced if our net import of biocapacity were reduced?

Questions for Discussion:

12. Earlier you saw that the pre-1930’s Idaho Falls population had lower survivorship than the post 1970’s population. Do do you think the trends shown for pre-1930’s Idaho Falls’ population could be similar to those of present day developing nations?

13. If our entire US population was considered a developing nation pre-1930’s, what does this tell you about future consumption and carbon footprints of today’s developing nations?

14. Do you think this is sustainable?

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Biol 1100L Population Ecology Lab 2

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Biol 1100L Population Ecology Lab 2

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Biol 1100L Population Ecology Lab 2

3-1

Biol 1100L Biodiversity Lab 3

It is estimated that there could potentially be 30 million species on Planet Earth. The two million species that have been described and named are organized into three domains (Figure 3-1); Bacteria, Archaea, and Eukarya. These domains are further organized into smaller and smaller groupings. Today you will learn more about this system of organization and over the next five labs you will be introduced to a variety of organisms.

Part 1. Systematics

The study of the diversity of organism and of the relationships between them is the scientific field of systematics. Systematics is important because it creates the foundation upon which all other biological disciplines are based. Phylo- genetic systematics provides methods for infer- ring evolutionary relationships. Relationships are inferred by distinguishing between charac- ters that represent an ancestral condition for the organisms in question and those that represent the derived condition. Shared derived charac- ters among organism are evidence of common ancestry. A phylogenetic tree (Figure 3-2) is graphical representation of the evolutionary re- lationship between taxa.

2. Who are you and your hypothetical sister’s most recent common ancestors?

Figure 3-2. Each node along a branch of the phylo- genetic tree represents a population that lived at a particular point in time. The root is the original popu- lation. Nodes mark the population that split to pro- duce two daughter populations. The tips represent the populations that are currently living (extant).

Imagine that you have a sister and a cousin. Your sister and you share ancestors, your mother and father. You and your sister share other ancestors too as do you and your cousin. These may include your father’s or mother’s parents, their parents, and so on. Evolutionary biologists refer to the ancestors two individuals

share as common ancestors (held in common or shared). You are more closely related to your sister than to your cousin because your most recent common ancestors with your sister (your mom and dad) lived more recently than your most recent common ancestors with your cousin (your grandparents). We can use similar reasoning in thinking about the evolutionary relationships among populations and species.

Name:_______________________________ Section:____

Figure 3-1. A phylogenetic tree of the three domains of life.

1. In the following diagram label the arrows most recent common ancestor and the root.

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Biol 1100L Biodiversity Lab 3

3. Who are you and your hypothetical cousin’s most recent common ances- tors?___________________________

4. Who are you more closely related to, your sister or your cousin? Why?

5. Who lived more recently your most recent common ancestors with your sister, or your most recent common ancestors with your cousin?___________________________

6. In the diagram: A. Which arrows (x, y, or z) point to the

most recent common ancestor of 1 and 3?

B. Which arrow points to the most recent common ancestor of 1 and 2?

C. Which lived most recently, the most re- cent common ancestor of 1 and 3, or the most recent common ancestor of I and 2?_____________________________

D. Is 2 or 3 more closely related to the 1? _______________________________

E. Draw an arrow on the diagram showing the direction of time.

Part 2. Taxonomy

The discipline of systematic encompasses the field of taxonomy which is the classification, de- scription, and naming of groups of organisms. Since the 18th century, biologists have sub- scribed to a standard protocol for the descrip- tion, naming, and classification of organisms. Classification is a utilitarian product of system- atics, a tool that provides names for groups of species and serves as a way to retrieve in- formation. It allows people across the country and world to communicate more efficiently with each other.

The fundamental unit of classification is the species. Most often a species is defined as a group of individuals that are capable of inter- breeding under natural conditions producing fertile offspring.

In formal biological classification, species are grouped according to estimates of their simi- larity or relatedness. Such groups are called taxa (singular, taxon). The taxa are listed in a hierarchical pattern. The most commonly used groups in the system of zoological classification are shown in Table 3-1 (listed from the most in- clusive to the most exclusive):

In this system, the animal kingdom is divided into a number of phyla (singular, phylum). Each phylum is divided into classes, classes into or- ders, orders into families, families into genera (singular, genus) and genera into species. A classification developed for a taxon will be af- fected by the particular characters used, the