Outbreeding depression

Outbreeding depression means that when animals with different genetic makeups have babies, the babies aren't as healthy or as strong as when animals with the same genetic makeup have babies. To make it simpler to understand, say you have two dogs, one is a Chihuahua and the other is a German Shepherd. When these two dogs have puppies, the puppies won't probably look or act like either of their parents - they might be small and skittish like the Chihuahua, or big and strong like the German Shepherd, or a mix of both. But whatever it is, the puppies won't be as strong and healthy as if both parents were the same breed. That's outbreeding depression.