I remember reading a story, perhaps by Clarke, Heinlien, Asimov, or Vonnegut, in the
70s or 80s, which described a galaxy (our own) that had many star systems colonized,
And over a number of centuries you could look at a map of the worlds, and watch them
Wink out one by one because genetic manipulation had been done and a robust copy
Of the human genome had not been preserved, and the populations died.

That's about all I remember of the story, but it stuck with me for some reason. I seem to
Remember it being a short story perhaps by Clarke, but I cannot be sure.

Thank you.