Evolution is not slow and steady. If the conditions are right it can take hold very quickly. Most of evolutionary history is equilibirium with small bursts of rapid change when the environment shifts significantly.
It didn't take us a few hundred millenia to turn grey wolves into chihuahuas, and with the right stimulus nature could do it too.
I didn't say they couldn't be thousands of years, but suggesting hundreds of millenia ignores many observed events that have taken place on a much, much shorter time scale. The numbers referenced in the wikipedia article aren't even in their supposed citation, which is definitely not written by a supporter of the theory.
I choose grey wolves into chihuahuas because it's an example of a complex mammal undergoing significant genetic change over a much shorter time period than 100ky. For less complex animals there are even more dramatic examples.
I'm talking about evolution of different species, a much more significant change than variation within a species. Despite morphological and behavioral differences, wolves and dogs are still the same species. It took millions of years for fungi to evolve into decomposing wood.
Evolution of new species may not be necessary to survive all environmental changes, and not all speciations are similar in terms of genetic difference. Coyotes can still breed with wolves and dogs.
