However, such hybrid offspring can only survive in captivity free of predators.

The hybrids of mallards and the yellow-billed duck are fertile and can produce more hybrid offspring.

The prairie falcon was trapped and the eggs removed, incubated, hatched and the hybrid offspring were given to falconers.

The hybrid offspring were fertile and able to breed successfully with each other, indicating that the two species of bear are closely related.

Such speciation may be a product of reproductive isolation which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow that results in genetic divergence.