Answer:
D) sympatric speciation and habitat isolation
Explanation:
Sympatric isolation is a form of evolutionary process whereby different species from an ancestral origin evolve within the same geographical environment as a result of reproductive isolation.
Habitat isolation is a form of reproductive isolation which occurs when two populations of a species inhabiting overlapping habitats become unable to interbreed with each other.
Reproductive isolation (habitat isolation) that occurs in the fleas is as a result of the new species becoming separate from it's ancestral species which feed only on pronghorn antelopes, although both species can still be found in the same geographical location (rangeland). The new species now have preference for cattle blood, and so are now found on cattle.
In the situation of the two new species of flea that would evolve, it can be said to an example of sympatric speciation and habitat isolation, since the host mammal is assumed to be their habitat and both the cattle and pronghorns often associate with one another in the same open rangeland.
The correct answer is option:
The peak of the bell curve has shifted to the right, with a greater frequency of crickets with long legs and a lower frequency of crickets with short legs.
The given condition would lead the directional selection of the crickets with long legs. Directional selection leads to shifting of curve in one direction, which is more suitable.
The crickets with short leg get easily caught by predators, so, after sometime, there would be a decrease in number of the crickets with short leg. At the same time, the crickets with long leg would manage to save themselves and their number would comparatively increased.
