In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. in rangelands of the western united states, pronghorns and cattle often associate with one another. if some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas' habitat?

1. reproductive isolation
2. sympatric speciation
3. habitat isolation
4. prezygotic barriers