Figure 14.22 Counter-adaptations of predators to prey chemical defenses. researchers measured the swimming speed of black snakes before and after being fed the skin of cane toads, which contains toxins. They found that snake populations that had coexisted for the longest times with the toad had the lowest susceptibility to the toad toxin.

Data from B. L. Phillips and R. Shine, An invasive species induces rapid change in a native predator: Cane toads and black snakes in Australia, Proceedings of the Royal Society B 273 (2006): 1545–1550.