Answer: Sympatiric speciation and habitat isolation
Explanation:
Sympatric speciation happens when populations of a species that share the same habitat become reproductively isolated from each other.
For habitat isolation to occur, populations do not need to be separated by great distance. Instead, they must occupy different habitats, even within the same area. In this situation, some of the fleas have started to feed on a cattle instead of pronghorns like the others. They have also started mating with conspecifics found on the cattle thereby giving rise to a new species. This therefore shows Sympatiric speciation and habitat isolation.