Geological evidence indicates that two landmasses, separated by a deep ocean channel, have been moving apart since 45 million years ago. You are studying a group of organisms that has widespread populations on both of the landmasses. Which is the most likely hypothesis for the group's evolutionary history?
A) The group's ancestors were definitely present on the original landmass.
B) The group's ancestors cannot have been present on the original landmass.
C) If the group's ancestors could not move across the open ocean, it is very likely that they were present on the original landmass.
D) The group's ancestors must have independently colonized each of the landmasses from a third location within the past 45 million years.

Question

Quizplus · Accepted Answer

If the two landmasses have been moving apart since 45 million years ago, it is unlikely that the group's ancestors could have independently colonized both landmasses from a third location within that time frame. Therefore, if the group's ancestors were unable to move across the open ocean, it is very likely that they were present on the original landmass and subsequently diverged into separate populations on each landmass as they moved apart.

Geological Evidence Indicates That Two Landmasses, Separated by a Deep