IN the short run there's no real damage. In some water sheds in the wild there might be only a handful of successfully breeding fish. In short..it happens.
If you consider that a lot of fish breeders manage to maintain the majority of a batch of fry for future sale you could argue that the "survival of the fittest" is thrown right out the window since ALL of the fry...regardless of their genetic make up...make it to a large size and are sold to the public. Wild population of spawning fish will actually continue having fry even as the last brood continues to grow. In the wild, the larger fry snack on the smaller (new brood) and life goes on as THEY get bigger and snack on the next. That's the way mom nature makes sure only the strongest survive.
Not to belabor the point, but there are populations of cichlid species in aquariums today that are "overall" genetically inferior after YEARS of breeding through the same bloodline. Umbriferum come to mind. Years back there was a supply of "wild " stock that made it into the hobby that kept the species going strong. I think the fish that most have in their tank now are...not as "healthy". I've seen many that survive to a particular size...then get ill and die. May be years...but it happens. THe largest I had ever seen was a friend who had a 21" specimen in his tank (now dead). I spoke with an old timer this past weekend who had one twenty years ago...30+ inches and lived for many years. Just my 2 Cents.
Sorry for the info overload. Enjoy breeding your Jacks. Watching it happen is one of the best things that happens with this hobby.
Mo
