ooOoOoOAnaOoOoOoo wrote:
Actually, it's a myth, Arrant, that genetic diversity makes a species stronger. What makes a species genetically viable are genes that promote it's survival no matter what those are. Genetic diversity often introduces genes that are not conducive to survival into a group that did not have such genes before.
It's only when the genes are bad and paired together that you see these diseases and whatnot crop up that can lead to illness and sometimes, death.
If you have a population without these genes and they are interbreeding, how can it be bad unless something mutates and a condition arises that way.
So you see, it's the genes that are to blame, not the actual breeding practices. Most people do not like the idea of interbreeding, and are disgusted by it. This is the real reason why it's not good.
genetic diversity is good where the environment is changing or when a species is moving into a new habitat. Since most habitats do change over time, genetic diversity is positively associated with long-term survival of a species.
In very rare, stable environments, species may even start to self-fertilize or clone themselves when they hit upon a successful phenotype; at that point, gamete mixing becomes a liability rather than an advantage.
When you study animal husbandry you find out genetic diversity is seen as high risk. This is how various bloodlines obtain defects which run in their line. Once it is introduced, it generally stays in the bloodline. This is why some bloodlines are well known for producing certain faults.