As a general rule, when the individuals of a population encounter a new environmental stress, some individuals in the population will die prematurely and some individuals will survive.

If the reason for their survival (such as a slightly enhanced ability or trait) can be passed on to their offspring (that is, it's genetically encoded), then the next generation should be better able to withstand the newly encountered environmental stress, and the population overall will be less susceptible to it.

Therefore, the key to the ability of a population to survive by adaptation lies in the rapidity with which the next generation, the more resistant generation, is produced by the survivors of this generation.

It follows that those species capable of producing a new generation very quickly should be better able to respond to a stress very quickly.

Those species that require more time for reproduction will be slower to adapt to the stress because of the additional time needed for them to produce stress-tolerant offspring.