Question

What is reproductive isolation? Describe any two types each of pre-mating and post-mating isolating mechanism.

Hint:

Think of it this way: \textbf{Pre-mating} barriers are like a "locked door" that prevents two species from getting together. \textbf{Post-mating} barriers are what happens when they manage to get through the door, but the "offspring" either doesn't survive or can't have its own children.

Answer 1

Reproductive isolation refers to the collection of evolutionary mechanisms, behaviors, and physiological processes that prevent members of different species from producing viable, fertile offspring. These mechanisms are crucial for maintaining the integrity of distinct species. Two types of Pre-mating (or Pre-zygotic) isolating mechanisms: These prevent mating or fertilization from occurring.

Temporal Isolation: This occurs when two species have different mating or flowering seasons or times of day. For example, two species of frogs might live in the same pond but breed at different times of the year, one in early summer and the other in late summer, so they never have the opportunity to interbreed.
Behavioral Isolation: This mechanism operates when species have different and specific courtship rituals, mating calls, or pheromones. If one species' courtship display is not recognized by another, mating will not occur. For instance, the specific song of a male bird will only attract females of the same species.
Two types of Post-mating (or Post-zygotic) isolating mechanisms: These act after mating has occurred, preventing the formation of a fertile hybrid.

Hybrid Inviability: In this case, a zygote is formed by the fusion of gametes from two different species, but it fails to develop or dies before reaching maturity. The genetic incompatibility between the two species prevents normal embryonic development.
Hybrid Sterility: The hybrid offspring is successfully born and develops into a mature adult, but it is sterile and cannot produce functional gametes. The classic example is the mule, which is the sterile offspring of a male donkey and a female horse.