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Chapter 5
1. Sickle-cell anemia is an example of _____________________ because
_________________________.
a. stabilizing selection/ there is only one common phenotype in populations
where malaria is prevalent.
b. directional selection/ malaria is promoting the loss of the sickle allele in
populations.
c. a balanced polymorphism/ the sickle allele is maintained in the population
because heterozygotes are less susceptible to malarial infections.
d. a balanced polymorphism/ homozygotes without the sickle allele acquire
immunity to the malarial parasite and transfer that immunity to their
offspring that carry the sickle allele.
2. The formation of new species as a result of geographical isolation is called
a. allopatric speciation.
b. sympatric speciation.
c. parapatric speciation.
d. disruptive selection.
3. When speciation occurs in small local groups, called demes, within a larger
population has occurred.
a. allopatric speciation has occurred.
b. sympatric speciation has occurred.
c. parapatric speciation has occurred.
d. reproductive isolation has occurred.
e. Both b and d have occurred.
f. Both c and d have occurred.
4. Long periods of stasis interrupted by brief periods of evolutionary change
characterize
a. phyletic gradualism.
b. the punctuated equilibrium model.
c. sympatric speciation.
d. parapatric speciation.
5. DNA and proteins that are conserved evolutionarily are probably
a. detrimental to survival and thus are weeded out.
b. essential for survival, so they tend to be retained with few changes. Any
change is likely to be detrimental and will be selected against.
c. never have experienced a mutational change.
d. useless in establishing evolutionary relationships among animals.