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BIS 2B F09 More practice questions for Midterm 2 1 . The Old-World Amish community in Pennsylvania began with 200 families that emigrated from Europe. This group permits marriage only among those descended from the original group. Some alleles that are rare in the rest of the American population are common in this group. This difference is best explained by: a) directional selection b) high mutation rates c) the fact that each family has many children d) founder effects e) short generation times 2. Define 'agent of selection', and identify the agents of selection in each of the following examples: a) changes in color in peppered moths = bird predation (the environment makes some types more or less visible to bird predators). b) eyespots in peacock tails = peahens—intersexual selection c) large body size in male elephant seals = other males fighting – intrasexual selection d) maintenance of the allele causing sickle-cell anemia in parts of Africa = presence of malaria (it alters the fitness landscape and makes heterozygotes the most fit genotype). 3 . Human blood can be typed using a three-allele system (IA, IB, IO). In a population at Hardy-Weinberg equilibrium, the genotypic frequencies were: f(IAIA) = 0.04, f(IBIB) = 0.01, f(IOIO) = 0.49 f(IAIO) = 0.28 f(IBIO) = 0.14. The frequency of the IAIB blood type was not calculated. What should it be? a) 0.01 b) 0.16 c) 0.03 d) 0.04 = 1 minus sum of all the frequencies e) 0.07
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4 . In a sample of 3000 earthworms, 81% of the animals were qq. If the Q locus has only two alleles and the population is in Hardy-Weinberg equilibrium, what proportion of the population should have the genotype Qq ? a) 1 % b) 9 % c) 18 % b/c sqr root of .81 = .9; 2 x .9 x .1 = .18 d) 81 % e) 90 % 5 . You are analyzing a data set for a population of fossil leg bones from mice. You have leg-bone-length distributions for 4 time periods. Over time the mean leg bone length has not changed, but the variance of the distribution has decreased. What kind of selection seems to be acting on leg bone length? a)
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This note was uploaded on 12/28/2010 for the course BIS 2B taught by Professor Strong during the Fall '08 term at UC Davis.

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