My 7th grade biology teacher explained, of breeding sweet pea flowers, that nature takes the <whole number> of <viable, healthy> plants, throws out the ones that are too (big, small, color deviant, vulnerable to pests, etc.) near the edge of viability or sustainability, so we are left with the best result for the current climate and conditions.
It seems to me that a convoluted genetic pool would not promote a genetic weakness, but prevent a genetic pollution of sorts. But, I should also think that breeding habits would play a part in this particular question, as the convolution may serve to balance or correct an aspect in process which favored diversity among smaller populations, previously.
"We must not presume a finished process, but look to where it may be going. What does the current evidence suggest a future generation might be? What information does our climate and environment provide for the genetic equation? Does nature build in resistance to pollution?" ~ A Great Teacher with a difficult name, who got us all to look at the whole system.