Drought is still a "typical" condition. (I.e. one from its environment, from the last hundreds of thousands of years or so.) Selection pressure worked on that.

Drought is still a "typical" condition. (I.e. one from its environment, from the last hundreds of thousands of years or so.) Selection pressure worked on that. Yes, it may be a condition that makes 10%, 50% or 90% percent of the population to die - and it is not a problem, in the grand scheme of things. Not normal conditions are things that were never tested, or never tested to that extend. E.g. an invasive species from a different continent, a chemical compound, different pH of water, etc. Consequently, many species die out completely - as there is not enough time for the selection of better-fitted genes for this setting. Also: compare with machine learning, and giving a sample out of the training dataset distribution (all photos are shot in good light, give one in the dark). Usually, the answer is meaningless.