Imagine you are a scientist studying birds living on a mountain. Some birds on this mountain have black throats and others have red throats, but they otherwise look very similar. According to the Biological Species Concept, what would you need to obser



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NOTE: Questions 1-10 deal with the same scenario. Questions 11-15 do not reference the scenario described in questions 1-10.


1) Imagine you are a scientist studying birds living on a mountain. Some birds on this mountain have black throats and others have red throats, but they otherwise look very similar. According to the Biological Species Concept, what would you need to observe in order to determine whether these birds are members of the same species?

2) Now imagine that you want to know about the niches of these birds. You notice that the birds with red throats prefer to live closer to the top of the mountain, above 6,000 feet, where the species of pine tree they nest in lives. These birds also eat the flightless beetles that burrow into the bark of these trees (this burrowing harms the tree). The birds with black throats live all over the mountain, nesting in all kinds of trees, down as low as 2,000 feet. They also eat insects, but only flying insects, of which there are many kinds.

a) Which type of bird is a specialist and which is a generalist with respect to nesting?

b) What about with respect to feeding?

c) What kind of species interaction is occurring between the pine tree and the red throated bird?

d) What about between flying insects and the black throated bird?

e) Are the two kinds of birds competing for food?

f) What about for nesting sites?

3) After further study, you notice that the birds with red throats have a layer of feathers next to their skin that insulates against the cold very well. However, this layer of feathers makes it very hard for the red throated birds to survive in warmer temperatures. The black throated birds lack this adaptation to cold temperatures but will still nest in colder areas. As with all tall mountains, there is an inverse relationship between average temperature and elevation, so that as elevation increases average temperature decreases.

a) When the red throated birds descend below 6,000 feet, what physiological state is being challenged?

b) Which type of bird has a more restricted range of tolerance with respect to temperature?

c) Which do you expect to have better survival and reproductive success above 6,000 feet?

4) Over 20 years of study, you notice that average temperatures on the mountain have increased 2 degrees centigrade, the population of red throated birds has declined 50%, there seem to be fewer pine trees, and about 5% of the red throated birds no longer have an insulating layer of feathers. What might explain the loss of this layer of feathers?

5) State a hypothesis of what you would expect to happen to the percentage of red-throated birds with the insulating layer of feathers if the average temperature continued to increase.

6) A colleague of yours who studies birds on a nearby mountain says she has never seen a red throated bird like yours on her mountain. After a great deal of research, you realize there are no other populations of these red throated birds anywhere in the world. What kind of species does this make your red throated bird?

7) Over an additional 20 years of study, the average temperature on the mountain has increased yet another 2 degrees centigrade, the pine trees have declined by about 30%, and the population of the red throated birds has declined to just 5% of what it was 40 years ago. You worry that the red throated birds you have studied your whole life may go extinct. But you know there is a mountain 200 miles to the North that is much taller and colder, has the right kind of pine trees and beetles, and appears to be perfect habitat for the red throated bird. This new habitat lacks any of the black throated birds.

a) Would the Endangered Species Act consider these pine trees “Critical Habitat” of the red throated birds?

b) Why or why not?

c) Would it be a good idea to introduce the red throated bird to this new mountain habitat to save the species?

d) Why or why not?

8) One of your students, who inherited your research project after you died, moved the last remaining red throated birds to the other mountain (it was your dying wish). About 80% of the birds they moved had no insulating feathers, but 20% did.

a) Could these birds become separate species on the new mountain?

b) Why or why not?

9) To better understand the genetics of throat coloration, your student sequences the genome of the birds. Two alleles exist for the throat color gene in these birds. One allele generates yellow throats if food is plentiful and red throats if food is not plentiful. The other allele generates red throats regardless of food supply. In their new habitat, the birds lack competitors so they are constantly pushing up against the limits of their food supply, leading them to starve.

a) What color will their throats be?

b) Could there be changes in the proportion of the two alleles over time?

c) Why or why not?

d) Would evolution be possible with respect to throat color in this scenario?

e) Why or why not?

10) After 10 years of study, your student started to notice that, occasionally, a male bird would have a yellow throat. This made him more likely to be eaten by hawks, but the female birds preferred to mate with yellow throated males because it showed that they were good at finding food. Over another decade, your student collected data showing that the proportion of males with yellow throats went up to 10%.

a) What kind of selection is driving the increase in yellow throated males?

b) Does the increase in proportion of yellow throated males constitute speciation?

c) Why or why not?

NOTE: The following questions are not based on the scenario above.

11) What are the three conditions that need to exist in order for evolution to occur? For each condition, explain why its absence would prevent evolution from occurring.

12) Carbon, Nitrogen, and Phosphorus are important elements for life on Earth. Ecosystems cycle these nutrients using energy ultimately derived from the Sun. What are the human activities that have impacted these cycles since the industrial revolution? For each element give the approximate percentageincrease in flux caused by industrial processes, and describe some potential impacts of the changes to these cycles on ecosystems, human beings, and/or the planet.

13) Carbon and Nitrogen are readily available in the atmosphere, but Phosphorus is not. Phosphorus is found only in rocks.

a) Where does Phosphorus go after it has been taken up by a plant?

b) What consequences does this have for human beings who depend on industrially mined Phosphorus for our food supply?

14) Draw a simple food web and corresponding trophic pyramid. In both diagrams, include a photoautotroph, three levels of heterotrophs, and a detritivore. Also show where the energy entering the system comes from. Use arrows to show how the matter and energy in the system move. Label all parts of the diagrams.

15) Assume that 1,000 kilocalories of energy are available in the photoautotroph from the above question.

a) How much of that energy will be available in the first level of heterotroph?

b) What about the second level?

c) The third level?

d) Where does energy go between trophic levels?

16) What are the first and second laws of thermodynamics, and why is life sometimes referred to as a war against entropy?

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