concept

Insurance hypothesis

The idea in ecology that biodiversity is a form of insurance against environmental fluctuation: in a diverse ecosystem many species perform overlapping roles, so when a disturbance wipes out some of them, others are already in place to carry the function forward. Formalized by Yachi and Loreau (1999), it holds that diversity is not decoration but a portfolio of different responses to an uncertain future — degeneracy written at the scale of a whole ecosystem. It is a large part of why a burned patch of forest is reseeded by a crowd of species, not one fragile specialist.