A population of bison was separated by the construction of a new interstate. The construction also separates bison east of the interstate from its natural predator, and bison west of the river from the primary source of water. Much time passes.
The horns of bison east of the interstate become less sharp than those west of the interstate. This is an example of:
Answer: B, Divergent evolution. Since the bison east of the interstate no longer have to combat its natural predator, sharp horns are no longer needed.
Key Takeaway: When a population becomes separated into two distinct populations, changes will occur in both new populations based on the different environments. Bison east of the river are separated from the natural predator of the species, and changes will occur in its physique to represent that, including a loss of sharp horns.
Photo: Bison, Stefan Didam