試題詳解

72. The tails of UCSD campus male dark-eyed juncos were, on average, 36% white, whereas the tails of male juncos from the original colonizing population averaged 40-45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to ______.
(A) a genetic bottleneck
(B) a founder effect
(C) gene flow between populations
(D) mutations in the UCSD population
(E) stabilizing selection