Goannas that evolved by natural selection that can explain the declining incidence of toad-induced deaths.

The one trait that belongs to that description is related to the tolerance to toad poison. Researches have stated some general condition in order for the natural selection to have cause the eolution of this trait. Three of them are: Individuals must vary phenotypically or genotypically, Individuals pass on at least some of their traits to their offspring and Individuals with different traits must differ in their survival or reproductive successduring the struggle for existence.