(5.01 MC) SC.912.L.15.13
Water frogs that live on Greek islands in the Mediterranean were separated from mainland
water frogs when salt-water levels rose to form the islands, allowing differences in the isolated
populations to develop. Suppose one large group of frogs on the mainland uses a low-pitched
call to attract mates while otherwise identical frogs on a nearby island use a high-pitched call. A
boat carries a few high-pitched frogs in its cargo to the mainland. Which of the following answer
choices best predicts the outcome of this event?
A. The frogs from the islands are quickly eliminated by natural selection because they sound
different than the mainland frogs,
B. The frogs from the islands introduce new genes to the mainland gene pool, causing a change
of pitch in the mainland frog population,
C. The mainland frogs learn to make high-pitched calls and pass on this adaptation in their genes
to future generations.
D. The mainland frogs respond to competition with the new frogs by genetically mutating their
offspring to produce high-pitched calls,

Explanation: We can figure out this answer by using simple process of elimination. The first answer is clearly incorrect because it is not a deciding factor of survival. The pitch of it's croak will not change anything. So there is no reason they will be eliminated. The third answer is also incorrect because since the higher pitch does not help the frog's survival, there will be no need for adaptation towards higher pitch. This is the same for the fourth answer. So the answer must be B.