NYU scientists have traced the evolution of tomcod fish that’s been driven by pollution in the Hudson River. The NPR article is nice because it really breaks down how fish with the right genes preferentially survived the PCBs and dioxins in the river, and passed their genes on.
It also turns out that the fish “selected” for pollution tolerance end up being more sensitive to other things, like high water temperatures. It really puts, “survival of the fittest” in context. The fish are “fit” for polluted rivers, but not “fit” for warmer water.