Natural selection or survival of the fittest can cause a major evolution as the species at risk need to stay alive and therefore need to become more adapted to the situation at hand. The species can evolve through generations to become more crafted to the predatorial habits of their predators. If the females are less at risk than the males then the males might evolve to become more protected or if some of the species live in a different situation maybe not even that far away, that can have a big impact on the evolutionary habits of the species at hand.
I hope I'm right