Dawkins was careful to place ‘stringent requirements’ on the idea of the extended phenotype. Although it is a speculative concept, he dutifully reminds us, it is a ‘tightly limited speculation’. There are three crucial criteria that have to be met to prevent phenotypes becoming too extended (if a beaver’s dam is an expression of the beaver’s genome, then what about the pond that forms upstream of the dam, and the fish that live in the pond, and …?).
In The Extended Phenotype, Richard Dawkins introduced the concept of the extended phenotype, which is the idea that an organism's phenotype (physical and behavioral characteristics) can have an impact on the environment and other organisms. However, he placed "stringent requirements" on this concept, meaning that he set strict rules for when it can be applied.
