Rapid evolution of other species happens all around us all the time — and many of the most extreme examples are associated with human influences.
Consider three examples:
Commercial fishing. When fishing pressure is high, the fish evolve to reproduce when they are younger and smaller, and thus tend to have fewer, smaller offspring. This evolutionary change can, in turn, reduce fisheries yields and the sustainability.
But is this really a form of evolution? That is, are the changes irreversible? Will speciation occur in the affected population, so that the two new groups cannot interbreed with each other? Or, if the bottom fell out of the fish market, would everything be pretty much the same a couple of centuries from now?
Invasive species. The movement of species to new places in the world instigates evolution in those invasive species, which increases their rate of spread and impact on native species. Those native species can then sometimes evolve in response, potentially arresting the invader’s spread and mitigating its impact.
Again, are these irreversible changes leading to speciation?
Urbanization. The development of cities dramatically changes many aspects of the environment and, hence, can instigate evolution in a variety of species. As examples, plants evolve decreased seed dispersal to compensate for the expansion of uninhabitable pavement, animals evolve resistance to industrial and residential chemicals, and bacteria evolve resistance to antibiotics. Paper. (copy of paper must be requested) – Kiyoko M. Gotanda, Andrew P. Hendry, and Erik Svensson. Human influences on evolution, and the ecological and societal consequences. Philosophical Transactions of the Royal Society B, December 2016 DOI: 10.17863/CAM.6418 More.
Do we have any reason to believe that if the city fell to ruins, the plants would not simply go back to their former habits?
Note: Darwin’s finches, pictured above, are in fact testimony to hybridization among closely related groups of birds, not of evolution—unless we think of evolution as a revolving door within otherwise fixed species. But that’s not how we are supposed to see it.
One can call any changes one likes “evolution”—but then one cannot turn around and say that one has demonstrated any particular thesis about it.
See also: Why are there so many “species”? Well, maybe there aren’t. In the current mess, how would we know?
Wayne Rossiter on teaching Darwin’s unquestionable truths
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