[stultissimus]

In general we can conduct 'directed evolution' (selective breeding is an example). In this example, however, we're talking about improving the resistance of Halderia to the possible future mutations the viruses could develop to exploit them. This is a much, much larger harder to search space; the cost function is not well defined.

[eru]

Well, whenever your population of halderia is big enough, you can dial up the radiation a bit. Most mutations will be bad, some might be good.

When you need the population size to recover, you dial down the radiation a bit.