Evolution is generally seen as an arms race. Those that are most adept at surviving to pass on their genetic material, others die or at least fail to mate. However, in the case I am looking at, there is no real threat to the population's survival. At least not enough to cause any significant short term pressure on the population.
For universe I am constructing, there exists a race of powerful beings that naturally emit a powerful energy that previously did not exist in the universe at the levels these creatures emit it. To draw a comparison, their energy release is akin to human release of green house gasses. It exists and is produced in nature, but now these guys are emitting it at a higher than normal levels and it is damaging. Now for various reasons, they can't get back to their own dimension and they are the only sentient life in the universe as it is very early in the universe's creation. They are also selfishly irresponsible and keep producing little energy emitters of their own (generally at a rate of 2.3 per bonded for life pair. At least according to existing census information). The plan is to have all (or most) sentient life evolve from these guys, but in order to not destroy their new home they would have to do something about their emissions issues (these emissions are natural so ideally they would "evolve away").
Is there a potential parallel for this in real life? I ask because I am attempting to keep hand waving to a minimum by basing the phenomenon on a real world example.