There's something called the "50/500" rule, which broadly indicates that a population needs more than 50 effective members to avoid short-term extinction and mo

There's something called the "50/500" rule, which broadly indicates that a population needs more than 50 effective members to avoid short-term extinction and more than 500 to avoid long-term inbreeding depression. You can read more about it, and the math that governs it, in this pdf: http://assets.press.princeton.edu/chapters/s12_9242.pdf http://assets.press.princeton.edu/chapters/s12_9242.pdf