The western United States contains a series of tall mountain ranges that also extend far down into Mexico. Two of the largest of these ranges are the Rockies and the Sierra Madres, but they are all part of the same mountain-building event that occurred many millions of years ago, and they all have similar features. Much of the vegetation on these mountaintops is the same, or very similar, and they are often referred to as the "Sky Islands" because of their similarity to each other and their isolation from the lower, drier areas surrounding them. With global climate change producing increasingly visible effects, conservation biologists fear that these mountaintop ecosystems will undergo major changes in temperature and humidity and that the many endemic species that live there may literally have no place to go.
Large predators and omnivores, such as mountain lions and bears, roam these mountain ranges.
Which of the following statements is true?

A) Because of habitat fragmentation and alteration, the individual populations of these SkyIslands have more biodiversity than they did in the past.
B) Because of habitat fragmentation and alteration, the individual populations of these SkyIslands have less genetic diversity than they did in the past.
C) Because of immigration and emigration, the individual populations of these Sky Islands have less biodiversity than they did in the past.
D) Because of extirpation, many of these individual populations have more biodiversity than they did in the past.
E) Because of immigration and emigration, the individual populations of these Sky Islands have more genetic diversity than they did in the past.