Chernobyl's birds adapting to ionizing radiation. "Laboratory experiments have shown that humans and other animals can adapt to radiation, and that prolonged exposure to low doses of radiation increases organisms' resistance to larger, subsequent doses. This adaptation, however, has never been seen outside the laboratory in wild populations."
Extinction Events That Almost Wiped Out Humans. "The really interesting thing about a population bottleneck is the effect it has on evolution. With a small population, mutations get passed through a very large percentage of the species' members. Detrimental mutations could be devastating and lead to outright extinction. Beneficial mutations, however, could cause fairly fast shifts in the population."
From Arid, Salty Desert to Permaculture Garden: Greening the Desert Revisited (note: not a lot of data; still dependent on intermittent rainfall)
So what seems to have happened to the Green Place was that the aquifer was contaminated with waste or salinified, right? Given its proximity to a salt plain, I'm going to guess salinification, since salinfication will fuck over your agriculture really quickly, where plants will keep growing in the event of other kinds of contamination, even if you don't want to eat those plants. However, there was still a lot of moisture hovering in the air. Idk, I imagine that something is going to speciate somewhere that's capable of using that moisture. And there's a feedback effect; I feel like the green plants we see on top of the Citadel are probably capable of harvesting what moisture from the air that there is, plus they're going to put out moisture, which will lead to at least probably some lichen, which is a real first step in getting an ecology going. I have to go now and can't read about desert species at this exact second but I am super fascinated, argh. SO INTERESTING.
ETA 1:
Salt-tolerant plants for the US Southwest - some of these plants are North America-specific, but, for instance, acacia is endemic to Australia and has edible seeds and shoots. (In fact, they're so salt-tolerant that they're an invasive plant in salinizing parts of the US). I just fell down a deep research rabbithole about bush tucker. The upshot: there are a lot of plants that will put up with a lot in their growing conditions, though they often get their revenge by being full of cyanide and requiring laborious leeching to eat.
ETA 2:
Plants and animals of the Namib Desert (so closer to the actual filming location). Oh my god, fog beetles. What an interesting planet.