does evolution accelerate in times of hardship?

Question

or slow in times of plenty?

Answer 1

It's slightly more complex, actually.

As other posters have pointed out - the rate of mutation is fairly constant. However - in stable times of plenty, there will be more individuals to develop mutations, so the variation across the whole population should increase. But this, by itself, won't lead to increased evolution, as there's no selection (it *will* lead to slower "genetic drift", however).

In times of hardship, the selection will become more intense, as individuals compete for resources, so more traits will be selected out of the population. The overall variation will decrease, and this will result in evolution - or possibly in extinction.

If the "hard times" were of sufficient severity to cause mass extinction (like the dinosaur extinction), then when the "times of plenty" return, evolution will massively increase, as species evolve to fill the niches left vacant by the species that died out.

This is one of the theories behind the "punctuated equilibrium" model for evolution.

Answer 2

The rate of genetic mutations stays fairly constant but, if the environment changes, it increases the likelyhood that one of these mutations will provide an increased chance of reproductive success. It is the increase in reproductive success that changes species. If the hardship is so hard that only a very few members of the species survive (those who by good fortune were born with a mutation that helps thm survive) and the survivors are able to find each other and reproduce, then the change in the species will occur faster.

Answer 3

You would think that it would according to theory, yet there is not proof that this is true.