The White-Knight Hypothesis, or Does the Environment Limit Innovations?

Organisms often harbor latent traits that are byproducts of other adaptations. Such latent traits are not themselves adaptive but can become adaptive in the right environment. Here I discuss several examples of such traits. Their abundance suggests that environmental change rather than new mutations might often limit the origin of evolutionary adaptations and innovations. This is important, because environments can change much faster than new mutations arise. I introduce a conceptual model that distinguishes between mutation-limited and environment-limited trait origins and suggest how experiments could help discriminate between them. Wherever latent traits are plentiful, ecology rather than genetics might determine how fast new adaptations originate and thus how fast adaptive Darwinian evolution proceeds.