1. List the five conditions that can disturb genetic equilibrium in a population.(10) The five conditions are non-random mating, small population size, immigration or emigration, mutations, and natural selection.

2. What are three mechanisms for reproductive isolation?(6) behavioral isolation, geographic isolation, and temporal isolation.

3. According to the _________________________ principle, allele frequencies in a population can be disturbed by one or more of five conditions. Hardy-Weinberg

4. After a forest fire, a moose population is reduced to one tenth of its original number. By chance, the average moose that remain are larger than the average moose in the original population. This change in the population’s gene pool is known as the bottleneck effect

5. The genes carried by all members of a particular population make up the population’s gene pool

6. Natural selection acts directly on phenotypes

7. A(an) ____________________ uses mutation rates in DNA to estimate the time that two species have been evolving independently. molecular clock

8. In a rabbit population, the allele frequency of a gene for brown fur changes from 20 percent to 30 percent. What can you say about that population of rabbit? it is evolving

9. A change in the genetic material of a cell is called a mutation

10. In organisms that reproduce sexually, most variation that can be inherited is due to genetic recombination

11. Two populations that have overlapping ranges can remain reproductively isolated through temporal isolation or ___________ isolation. behavioral

12. Genetic recombination includes the independent movement of chromosomes during meiosis as well as crossing-over

13. A ____________ trait that has two alleles and that shows a simple dominant-recessive pattern will result in two phenotypes. single-gene

14. A __________ trait can have many possible genotypes, producing many possible phenotypes. polygenic

15. When individuals at only one end of a bell curve of phenotype frequencies have high fitness, the result is directional selection

16. When individuals with an average form of a trait have the highest fitness, the result is stabilizing selection

17. One group of birds has a short, parrotlike beak and another group has a long, narrow beak. What process has probably occurred? disruptive selection

18. Genetic drift tends to occur in populations that are small

19. The type of genetic drift that follows the colonization of a new habitat by a small group of individuals is called the founder effect

20. The situation in which allele frequencies in the gene pool of a population remain constant is called genetic equilibrium

21. In a certain population of 100 individuals, one fourth of the individuals have the genotype BB, half have the genotype Bb, and one fourth have the genotype aa. One day, 10 individuals with the genotype bb leave the area and cross a river into a new habitat. Which of these processes has changed the population’s gene pool? emigration

22. The separation of populations by barriers such as rivers, mountains, or bodies of water is called geographic isolation

23. A factor that is necessary for the formation of a new species is___________ isolation. reproductive

24. They mate and produce offspring defines the members of a _________. species

25. What situation might develop in a population having some plants whose flowers open at midday and other plants whose flowers open late in the day? temporal isolation

26. Which is the first step that occurred in the speciation of the Galápagos finches? founders arrived

27. The Galápagos finch species are an excellent example of speciation

28. The frequency of phenotypes for a typical _________ trait is most often illustrated as a bell- shaped curve. polygenic

29. What did the Grants learn about mate choice from the Galápagos finches? Finches prefer mates with beaks similar in size to their own.

30. An example of a ____________ trait is sickle cell anemia in humans. single-gene

31. What do Hox genes control? patterns of embryological development

32. A ________ mutation is a change in an organism’s genetic material that does not affect its overall fitness neutral

33. A dramatic reduction in the size of a population following a natural disaster can lead to change in the population’s gene pool known as the bottleneck effect.

34. In the type of reproductive isolation called _________ isolation, two populations are separated by barriers such as rivers or mountains. geographic

35. A(an) ____________________ is all of the genes that are present in a particular population. gene pool

36. When a population is NOT evolving, it is in a situation called genetic equilibrium

37. If two populations have been reproductively isolated and can no longer breed and produce fertile offspring, the process of _________________________ has occurred. speciation

38. In humans, skin color varies from very light to very dark, and many different phenotypes exist in between these extremes. Therefore, skin color is probably a __________ trait. polygenic