1. How Populations Evolve
Chapter 13
How Populations Evolve

2. Concept Check
This Basilosaurus fossil (an extinct, early whale) provides strong evidence that:
Whales originated in marine environments.
Whale ancestors were four-legged terrestrial animals.
Ancient whales swam faster than modern whales
Answer: 2

3. Answer
This Basilosaurus fossil (an extinct, early whale) provides strong evidence that:
Whale ancestors were four-legged terrestrial animals.

4. Concept Check
Darwin proposed the theory of natural selection as the mechanism of evolution based on three observations about nature. Which of the following were part of Darwin’s observations?
Populations have the potential to produce more individuals than the environment can support.
Individuals in some population have varied characteristics.
Variation in individuals appears to be inherited.
All of the above.
Answer: 4

5. Answer
Darwin proposed the theory of natural selection as the mechanism of evolution based on three observations about nature. Which of the following were part of Darwin’s observations?
All of the above.

6. Concept Check
Natural selection works with genetic variation. The ultimate source of genetic variation is mutation in the DNA (or RNA is some organisms). However in sexually reproducing organisms with long generation time what process(es) account(s) for individual variation?
Random fertilization
Crossing over
Independent assortment
All of the above
Answer: 4

7. Answer
Natural selection works with genetic variation. The ultimate source of genetic variation is mutation in the DNA (or RNA is some organisms). However in sexually reproducing organisms with long generation time what process(es) account(s) for individual variation?
All of the above

8. Concept Check
Evolutionary fitness is an often misunderstood concept. Which of the following imaginary individuals would have the greatest evolutionary fitness?
Sparrow A
Sparrow B
Sparrow C
Sparrow D
Sparrow A
Sparrow B
Sparrow C
Sparrow D
Beak size
13 mm
15 mm
17 mm
16 mm
Lifespan
2.5 years
2 years
3 years
Offspring that survive to adulthood 10 16 12 14
Answer: 2

9. Answer
Evolutionary fitness is an often misunderstood concept. Which of the following imaginary individuals would have the greatest evolutionary fitness?
Sparrow B
Sparrow A
Sparrow B
Sparrow C
Sparrow D
Beak size
13 mm
15 mm
17 mm
16 mm
Lifespan
2.5 years
2 years
3 years
Offspring that survive to adulthood 10 16 12 14

10. Interpreting Data
Only one run of the model is graphed. Note that the A1 allele went extinct after about 100 generations. Which of the following is most likely for additional trials?
A1 will always go extinct in less than 500 generations.
A1 will not go extinct in less than 500 generations.
A1 will either go to 1.0 or 0.0 in less than 500 generations.
Genetic drift is the change in the gene pool of a small population due to chance. This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.
Answer: 3

11. Answer
Only one run of the model is graphed. Note that the A1 allele went extinct after about 100 generations. Which of the following is most likely for additional trials?
A1 will either go to 1.0 or 0.0 in less than 500 generations
Genetic drift is the change in the gene pool of a small population due to chance. This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.

12. Interpreting Data
Here, three runs of the model are graphed. Which of the following is most likely?
About 50 % of the time A1 will go extinct in less than 500 generations.
About 67 % of the time A1 will go extinct in less than 500 generations.
About 67% of the time A1 will go to a frequency of 100% in less than 500 generations.
Genetic drift is the change in the gene pool of a small population due to chance. This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.
Answer: 1

13. Answer
Here, three runs of the model are graphed. Which of the following is most likely?
About 50 % of the time A1 will go extinct in less than 500 generations.
Genetic drift is the change in the gene pool of a small population due to chance. This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.

14. Interpreting Data
Here, three runs of the model are graphed for a larger population of How does the larger population affect the rate of drift?
A1 allele will never become fixed at 1.0 or 0.0.
It takes more generations for the A1 allele to become fixed at 1.0 or 0.0.
The greater population size indicates that A1 must be the dominant allele.
This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.
Answer: 2

15. Answer
Here, three runs of the model are graphed for a larger population of How does the larger population affect the rate of drift?
It takes more generations for the A1 allele to become fixed at 1.0 or 0.0.
This graph represents a computer model of the change in frequency of one allele (A1) (out of two at one locus) in a starting population of All other H-W conditions apply.

16. Strongly A B C D E Strongly
Biology and Society
One concept of conservation biology is known as minimum viable population. Some species’ populations are so fragmented and small that they may have very little genetic variability left. With minimal genetic variation in the population there is little likelihood that a population can adapt to an environmental threat such as a new disease. Florida panthers are at or below the minimum viable population level (estimated population less than 80).
Do you think that it is practical to use limited resources to conserve a population like the Florida panther?
Disagree Agree
Strongly A B C D E Strongly

17. Strongly A B C D E Strongly
Biology and Society
During the anthrax crisis of 2001, public health officials urged citizens to not take the antibiotic ciprofloxacin as a preventative measure. Public health officials were concerned that over use of ciprofloxacin would lead to resistant varieties of anthrax and other bacterial pathogens. Ciprofloxacin is one of the few readily available effective antibiotics that can treat anthrax.
Do you think that public health officials should more directly regulate the availability of ciprofloxacin to assure its proper use?
Disagree Agree
Strongly A B C D E Strongly

18. Strongly A B C D E Strongly
Biology and Society
For some science and religion seem to be at odds—especially with regard to the topic of evolution. Many evolutionary scientists hold devout religious beliefs. Like many devoutly religious people these scientists are able to reconcile their religion and their science. Others find the two ways of knowing to be in conflict. There is little doubt that a literate citizen should explore the interface between science and religion. There is a social controversy but there is not a scientific controversy.
Do you think that this issue should be a part of a science class?
Disagree Agree
Strongly A B C D E Strongly