If the researchers repeated this experiment, predict how the results would change for areas where cane toads have been present for 40-60 years.

• A. A much lower percentage of snakes would eat the cane toads offered.
• B. No snakes would eat the cane toads offered.
• C. A much higher percentage of snakes would eat the cane toads offered.
• D. The results would be unchanged.

Answer: (C)

Predators can adapt to toxic prey over time, either through natural selection favoring individuals that can tolerate the toxin or through learned tolerance. Cane toads produce potent toxins, so predators that try to eat them early on may be deterred or harmed, creating strong pressure for avoidance. In areas where cane toads have been present for 40–60 years, some snakes have evolved ways to tolerate the toxins or overcome the initial aversion, so a larger share of snakes would be willing or able to eat the toads. That’s why you’d predict a much higher percentage of snakes eating the cane toads offered. The idea that no snakes would eat, or that the result would be unchanged, doesn’t fit the expected evolutionary and behavioral response over decades of exposure.