Assignment task:
In Australia, cane toads were brought from Central America and introduced to try to control the beetles that were harming the sugar cane. It was hoped that they would act as a natural form of pest control. This was a very serious mistake. They did not consume the beetles, instead they began to spread and multiply and invade. There have been catastrophic consequences for local wildlife. Cane toads have deadly poison in glands on their skin that native snakes can die of almost instantly and there are many species of snakes being driven to extinction.
Several interesting effects have been observed. First, cane toads legs have been gradually increasing in size, particularly in areas where they are newly invading. Longer legs appear to allow them to jump further and thus invade faster into new territory. In the older places in their range where they first invaded they still have shorter legs and move slower. Similarly, local snakes have gotten longer. Longer snakes have smaller mouths and eat smaller prey.
In one paragraph describe how Darwin would explain the longer legs of toads and longer body of snakes. In your answer indicate things Darwin could observe if he was in Australia (see or measure) and things he could infer (conclude) from the observations.