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.

mammal

explanation:

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.