A good human example is the increased prevalence of extra digits in the hand and feet of members of the Old Order Amish in Pennsylvania.
Bottlenecks and inbreeding are especially deleterious to endangered species, which are small populations that are vulnerable to extinction.
REVIEW: Sickle-cell anemia first appeared in Asia, the Middle East, and Africa. The causative
allele entered the U.S. population when people were forcibly brought over from Africa prior to the
Civil War. In microevolutionary terms, this is a case of _____ .
REVIEW: Directional selection occurs when
REVIEW: Stabilizing selection occurs when
REVIEW: The introduction of a small population onto an island that results in a limited gene pool
for a population best describes
REVIEW: The sharp reduction of the gene pool and the numbers of a population through a severe
epidemic is an example of
REVIEW: Natural selection may occur when there are _____ .
a. differences in the adaptiveness of forms of traits to prevailing environmental conditions
b. differences in survival and reproduction among individuals that differ in one or more traits
c. both a and b
REVIEW: Directional selection _____ .
REVIEW: Disruptive selection _____ .
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