The Gene Pool; Equilibrium Factors 215 



15.15. Suppose the frequencies of A and a are .3 and .7, respectively, in a population 

 obeying the Hardy-Weinberg rule and mating at random: 



(a) What per cent of the population is composed of homozygotes with respect 

 to these genes? 



(b) What would be your answer to (a) after one generation of mating hybrids 

 only with hybrids? 



(c) How would the conditions in (b) affect the composition of the gene pool? 



15.16. Discuss, from a genetic standpoint, the advantages and disadvantages of cousin 

 marriages in man. 



15.17. In Thailand, heterozygotes for a mutant gene that results in the formation of 

 hemoglobin E are more frequent in the population than would be expected from 

 the Hardy-Weinberg rule. How can you explain this? 



15.18. Two inbred strains of mice and their V l hybrids are tested for locomotor activity 

 (measured for each subject in each group during three consecutive five-minute 

 periods) and for oxygen consumption. In both these respects the F, hybrid is 

 less variable than the parental strains. Propose a genetic hypothesis to explain 

 these results. 



15.19. Compare the reproductive isolates of people who were marrying in 1900 with 

 those marrying today. Which factors are the same and which are different? Is 

 the change desirable from a biological standpoint? Explain. 



