The current population of gorillas in the wild is quite low. Less than 100 captive gorillas, descended
from only a few pair of wild caught parents, are living in zoos around the word. Assume that funding
and space were available for a captive-breeding program for the purposes of releasing several hundred
offspring from the zoo population to replenish the endangered wild groupings.
1. From an evolutionary perspective, what would be the effect of this plan on the genetic
variability of the released individuals?
2. What effect might the level of genetic variability of released individual have on the long-term
survival of wild gorilla population? (consider your answer to the previous question)
A Florida theme park began a new promotion to attract visitors from New England and the
Midwest. Free alligators were given away to residents of these two areas if they booked their
trip between March and October and stayed at one of the resort hotels. Thousands of families
took advantage of this offer, carried their baby alligators back home, and raised them over the
winter. By the following spring, most of the “adopted” alligators had grown too large to keep at
home. Many Parents decided that the nearest river would provide a perfect habitat and
released their alligators to the wild. Several years later, the expected proliferation of alligator
had not occurred. The rivers were as free of alligator as they had been before the pets were
Local newspapers presented the following three explanations about the fate of the “missing”
alligators. Determine whether any of these three explanations are valid and can be supported
by principles of evolutionary change and extinction. Explain why you consider each of the
statement to be valid or invalid.
1. This is an example of directional selection. Directional selection, which occurs when members
of a species migrate to a new habitat with different environmental conditions, acted against
those alligators most sensitive to cold weather. Changes in the gene pool led to the formation
of a new “improved” species of alligator that was adapted to local conditions. They migrated up
and down the rivers establishing territories in new geographic locations around New England
and the Midwest.
2. Punctuated equilibrium is responsible for the observed lack of alligator. Speciation occurred
during the first winter, so by spring, the isolated alligator had evolved into terrestrial forma that
foraged in nearby wooded areas.
3. The alligators were not able to adapt to their new environment. Extreme weather changes
occurred too rapidly for evolutionary change to occurred the released individual were killed by the winter cold