Hey, I know that some species like Pere David's Deer are in danger of lack of genetic diversity due to a ridiculously small founding population. Since exotics started off with sometimes just a dozen or few dozen starting animals, are axis, blackbuck, Etc. In trouble down the line due to a small population of starting stock? How about super exotics like Impala, Markhor, and Wildebeest?

When Pere' David's deer entire world population got to around 12 or 13 they went through a big bottleneck. I think you had a thread similar to this before and I can't remember if I posted on it or just thought about it! But when I was at University I did a research assignment on them, and even now with all the conservation work that's been done on them the fear is that in the next couple of hundred years the genetic bottleneck they went through has reduced their heterogeneity to the point where they'll just no longer be able to reproduce viable young.
As I remember, the genetic diversity now is still going backwards, albeit slowly. It's definitely a sad thing.

You see it more often in isolated populations of animals than with whole species. There is a plateau huge in Africa somewhere I remember in maybe Kenya or around there, where they are contained on all sides by an extinct volcana and they are essentially stuck in there. They've been doing genetic studies on the pride of lions in there and though they're really fit now, because they have no outside blood coming in they're inbreeding and eventually the population will likely crash. Wish I could remember the specifics of it but it's just been too long!

I'm not a scientist, but I do believe nature is more resilient than we give it credit for. There are small genetic mutations constantly that can allow a species to survive a bottleneck. Darwin's finches and many other critters on islands in oceana are said to come from very small founding stock and evolved from there. Heck, they even say humans went through a significant bottleneck in our evolutionary history. I tend to believe that a bottleneck is a dangerous point for a species, but there's a point past the bottleneck that there are enough individual animals and enough natural mutations where they can survive/thrive.

Pere David's aren't in any trouble now. Once you get past that bottleneck in numbers, genes start getting scrambled. There are so many separate herds it's easy to pull a new bull in and mix them some more. Good herd management is easy and key.

Think about it, each time a zygote is formed it has an opportunity to re-combine 23 different pairs of genes from both male and female contributors. That's a lot of recombination options if you bring in new bulls every few years.

No way are the larger population exotics in any danger, and with proper management neither are the smaller pop exotics.