Chapter 17 Questions

Chapter 17 Questions

Vocabulary: population genetics, normal distribution, genetic equilibrium, divergence, reproductive isolation, subspecies, speciation, mean, median, mode, gene flow, migration, nonrandom mating, genetic drift, mutation, fitness, biological species concept, extinction.

1.Illustrate how genetic variation is preserved or eliminated from a population through natural selection (evolution) resulting in biodiversity.

2.Explain how natural selection acts on individuals, but it is populations that evolve. Relate genetic mutations and genetic variety produced by sexual reproduction to diversity within a given population.

3.Explain how changes at the gene level are the foundation for changes in populations and eventually the formation of new species.

4.How do scientists study microevolution?

5.Define mean, median, and mode.

6.How is phenotypic variation measured?

7.How are genetic variation and change measured?

8.How does genetic variation originate?

9.What do we know about heredity that Darwin did not know?

10.What is the main source of genetic variation within a population?

11.What does the Hardy-Weinberg principle predict?

12.Consider these facts: Cystic fibrosis is a disorder that occurs in 1 out of every 2500 Caucasians in North America. Cystic fibrosis is caused by a recessive allele, and results when it is inherited in the homozygous condition.

1. Use the Hardy-Weinberg equation to predict the percentage of carriers (heterozygotes) of the allele that causes cystic fibrosis.
2. Calculate the frequency of the recessive allele.
3. Calculate the frequency of the dominant allele.
4. Determine how many of every 1000 Caucasian North Americans are likely to carry the cystic fibrosis allele.

13.How does sexual reproduction influence evolution?

14.What are the limits of the force of natural selection?

15.Describe species as reproductively distinct groups of organisms that can be classified based on morphological, behavioral, and molecular similarities.

16.What causes gene flow?

17.What is the genetic effect of inbreeding?

18.Identify the three patterns of natural selection.

19.Which form of selection increases the range of variation in a distribution?

20.How does divergence lead to speciation.

21.Trace the relationship between environmental changes and changes in the gene pool, such as genetic drift and isolation of subpopulations.

22.Give examples of ways in which genetic variation and environmental factors are causes of evolution and the diversity of organisms.

23.How do we know when new species have been formed?

24.Why is a species hard to define?

25.How do the number of genes for a character relate to its variation?

26.A population is in a state of genetic equilibrium when there is no genetic change occurring. What are the five forces that act against genetic equilibrium?

27.Explain the term species using the biological species concept.

28.Speciation is said to occur when former members of a population become reproductively isolated from one another. List and explain the various mechanisms of isolation that lead to speciation. Be sure to comment on the factors that may contribute to these models of isolation.

29.Describe the way in which selection acts on a population. What are the results of selection?

30.Describe the genetic results of selection in terms of what happens to the numbers of alleles.

31.Describe the role of geographic isolation in speciation.