Two populations of birds with somewhat different coloration live on opposite sides of a peninsula....

Question

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together in experiments, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. What keeps the two populations separate?

(A) Temporal isolation.

(B) Habitat isolation.

(C) Lack of hybrid viability.

(D) Behavioral reproductive isolation

.(E) None of the above.

Two populations of birds with somewhat different coloration live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds. When birds from the two populations are brought together in experiments, they produce young whose appearance is intermediate between the two parents. These offspring will breed with each other or with birds from either parent population, and all offspring of these pairings appear intermediate to various degrees. What keeps the two populations separate?(A) Temporal isolation.(B) Habitat isolation.(C) Lack of hybrid viability.(D) Behavioral reproductive isolation.(E) None of the above.

Answer 1

Hi!

It helps to understand the definitions of each option. This way we can rule out impossible choices and reinforce the correct answer. Let's look at them.

(A) Temporal isolation.

Temporal means having to do with time. In temporal isolation, their timing is off for reproduction. Two parties are not available to reproduce at the same time. ( their mating seasons are different, for example)

(B) Habitat isolation.

Habitat is related to where one lives. Habitat isolation occurs when any two living things ( or groups of things) can not interact because they are too far away, or separated by some barrier ( a forest, an ocean, a tank in a lab).

(C) Lack of hybrid viability.

Viability simply means the ability to survive. Hybrids would be the offspring of the two groups. So this would mean the mixed offspring to not grow into sexually reproductive adults.

(D) Behavioral reproductive isolation

This would be animals that don't mate because they have different rules of courtship. Male birds will often dance and posture to attract females. In this case, the male would be performing the wrong dance.

.(E) None of the above.

Now that you know the terms, let's see which we can rule out.

(A) Temporal isolation.

The text states that, "When birds from the two populations are brought together in experiments, they produce young" -- This shows us they can and do mate on the same schedule. We can rule this out.

(B) Habitat isolation.

The text explains that the birds," live on opposite sides of a peninsula. The habitat between the populations is not suitable for these birds."

(C) Lack of hybrid viability.

The text states that, " These offspring will breed with each other or with birds from either parent population". This tells us the hybrids both survive and reproduce. We can eliminate this possibility.

(D) Behavioral reproductive isolation

The text states that, "When birds from the two populations are brought together in experiments, they produce young" -- This shows us they can and do mate. We can rule this out.

.(E) None of the above.

Now that we The habitat between the populations i

Now that we've reviewed the definitions and applied them, can you find the answer?

Answer 2

(B), habitat isolation. The populations can interbreed and produce productive offspring, but they don't because the habitat in the middle is hostile (i.e. it sucks and nobody wants to go/live there), so they stay separate. But, for example, if the habitat in the middle changes, the populations might come back together.

Hope that helps!