Question

Evidence exists that during the millions of years in which the Grand Canyon formed, the canyon divided a single population of tufted-eared squirrels into two populations. One of these squirrel populations, the Kaibab squirrel, now lives in isolation from the other tufted-ear squirrels on the North Rim of the canyon. The other population, the Abert's squirrel lives on the South Rim. Some biologists think that the two populations of squirrels have evolved into two separate species. Other biologists think that the Kaibab squirrel is a subspecies of the Abert's squirrel.

Answer 1

A few of the squirrels manage to cross the canyon and breed with the squirrels on the other side.

Step-by-step explanation:

The formation of the canyon divide the population of the tufted ear squirrels into two different population or species of the squirrels. One is the Kaibab squirrel which lives in the north Rim of the canyon while the other is the Albert's squirrel that lived in the South Rim.

The Kaibab squirrel has a black belly, white tails and tufted ears while the features of the Albert's squirrel is that it has white belly, white tail and tufted ears.

Now the factors that could make the evolution or the formation of the squirrel population in two different species less likely is the few of the squirrels might have crossed the Grand Canyon and moved to the other part and breeded with the squirrels there. So both the species have somewhat similar features.