What class of barrier to gene flow would we be observing if we noted that the offspring of a lion and a tiger (two different species) are awkward, gangly beasts that have poor survival in the wild?

a. Premating barrier

b. Geographic isolation

c. Prezygotic barrier

d. Temporal isolation

e. Postzygotic barrier

The correct answer is e. Postzygotic barrier.

Explanation:

Different species can not mate and produce viable, healthy and fertile descendence, due to certain mechanisms of reproductive isolation.

These mechanisms involve different kinds of barriers that make it difficult for two different species to produce viable and fertile progeny.

One of these is the postzygotic barrier, which avoids the hybrid zygote to develope to adultness. In these situations, there is a mix of chromosomes that can not happen to meet or that they lack information.

There are cases in which the embryo dies, but some times the individual can reach some more advanced develope stages. If this is the case, in general, they can not survive because the organism is unhealthy. And if they reach adultness in good sate they can not leave descendence, as they are sterile.