In studying sub-populations of a small rodent that has a countrywide distribution in the widely varying habitat of Costa Rica,Irena and Irwin (out intrepid evolutionary biologists) becameinterested in a gene with two alleles where one of the alleles (A1)produced an enzyme variety that protected mice from the venom ofthe “bushmaster” (a highly venomous snake) and the other allele(A2) produced an enzyme that protected the mice against the venomof the “fer de lance” (another highly venomous snake).

1. In habitats where both snakes are present in significantnumbers, the genotype frequencies for were measured to be f(A1/A1)= 0.1; f(A1/A2) = 0.6; f(A2/A2) = 0.1. This represents a...

   1. a) population in Hardy-Weinberg equilibrium showing theevolutionary pattern of selection for the heterozygotegenotype.

   2. b) population that is in Hardy-Weinberg equilibrium showingevidence of selection against the heterozygote.

   3. c) population not in Hardy-Weinberg equilibrium showing theevolutionary pattern of selection for the heterozygote genotype

   4. d) population that is not in Hardy-Weinberg equilibrium showingevidence of selection against the heterozygote.

2. If aggressive human intervention removed all of the snakes inthe habitat described in the question above, which of the followingwould you not expect to happen to the allele and genotypefrequencies in the population?

   a) They would stay at exactly the levels they were at when thesnakes were removed. b) One allele or the other could become fixeddepending on the size of the rodent

   population.
   c) The number of heterozygotes would decrease. d) They wouldfluctuate randomly due to drift.

3. In studying habitats where both snakes are present insignificant numbers, Irwin and Irena found that over manygenerations, the allele frequencies tended to move first in onedirection and then in the other but always tended to move backtoward allele frequencies of f(A1) = 0.5 and f(A2) = 0.5. Thiscould be an example of...

   a) frequency dependent selection b) selection for adominant
   c) selection for a recessive
   d) underdominance

4. In one particular habitat with a small rodent population sizebut where both snakes were present in significant numbers, thegenotype frequencies were measured to be relatively close tof(A1/A1) = 0.38; f(A1/A2) = 0.24; f(A2/A2) = 0.38. This could be anexample of...

   1. a) overdominance

   2. b) inbreeding

   3. c) directional selection

   4. d) mutation-selection balance