Consider a simple scenario: A bird species lives on a tiny island in the Pacific Ocean. Due to a single mutation some individuals start breeding in the fall and not in the spring, like the other individuals of this species. As a result, these two populations (spring and fall breeders) living together evolve into two separate species. This is an example of: Group of answer choices

Reproductive barrier ⇒ isolation mechanism ⇒ seasonal or temporal isolation.

Explanation:

Reproductive barriers are isolation mechanisms that prevent mating between two or more species. The prezygotic mechanism avoids fertilization between individuals of different species, and the postzygotic mechanism avoids the zygote to develop and reach the adult stage.  

Among the prezygotic mechanisms, we might find behavioral isolation, seasonal or temporal isolation, sexual isolation, gamete incompatibility.

Seasonal or temporal isolation occurs when individuals of different species occupy the same area, have the same reproductive behavior, and their gametes are compatible, but they do not get to mate because their reproductive seasons differ.

In the exposed example, after the speciation process, both bird species living together are not capable of mating because one of the species mates in the spring and the other one breeds in fall.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

i think its the first one