A large population of squirrels becomes divided into two by the formation of a mountain range, due to tectonic
uplift. Then 500,000 years later, an earthquake and subsequent erosion by a river opens up a canyon corridor, which allows the two disconnected populations to rejoin in the middle of the mountain range. When the squirrel populations from the two sides of the mountain range encounter each other, they look identical, but possess very different courtship behavior. Females only respond to courtship displays from males characteristic of their own population. Genetic testing in the area of contact indicates that no interbreeding has occurred.
In paragraph form, address the following questions:
1) Has speciation occurred? Justify your answer.
2) What has happened to the populations on opposite sides of the mountain genetically?
3) If speciation has occurred, what kind(s) of isolating mechanisms are at play?
4) If we collected genetic data and produced a cladogram of these two populations along with other distantly related squirrel species, where would you expect these two populations to be found on the cladogram?