Bigger, better, stronger, faster..... Adaptation is incredibly powerful. I know that. I'm an evolutionary ecologist who studies these things. But wow, adaptation can drive changes in population size and rate of spread across a new habitat even faster than I would have predicted. In a new paper in PNAS, Marianna Szucs and Megan Vahsen (co-first authors), along with me and colleagues Brett Melbourne and Topher Weiss-Lehman, have shown that in only 6 generations, adaptation increases rate of spread across a new habitat more than 40% and bumps up population size close to 200% relative to populations that can't adapt*. So, all those examples, and there are many of them, of introduced populations that have adapted to their new ranges? Likely adaptation has driven population size, carrying capacity in the new environment, and the rate and distance spread from areas of introduction. Evolution is powerful powerful stuff.
* Just how does one prevent adaptation, you ask? We census the populations, and then replace individuals one-for-one each generation. The replacement beetles come from a large population that isn't exposed to the novel habitat, so can't adapt to it. That population is also large enough that drift and inbreeding are minimal over the course of a short 6 generation experiment. So, even in a sexual species, it is possible to effectively stop evolution.
* Just how does one prevent adaptation, you ask? We census the populations, and then replace individuals one-for-one each generation. The replacement beetles come from a large population that isn't exposed to the novel habitat, so can't adapt to it. That population is also large enough that drift and inbreeding are minimal over the course of a short 6 generation experiment. So, even in a sexual species, it is possible to effectively stop evolution.
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