The Evolution of Fire: Preserved proteins reveal a more accurate tree of life

Natural resources are currently valued primarily by their final commercial product, such as trees being priced according to their timber. Image courtesy of Wikipedia Commons

Forest fires, while harmful for individual plants, offer re­storative benefits for an ecosystem. Flammability, therefore, may be an example of group selection, a process by which a trait that may not be advantageous for individuals may become prevalent if it is beneficial for the group. Yale pro­fessor Carla Staver collaborated with researchers from Uni­versité Pierre et Marie Curie to study the individual scale of flammability trait selection with the fundamentally collec­tive nature of burning.

The researchers designed a spatial model that incorporates the idea that flammability traits offer direct fitness advantages for plant ecosystems but are disadvantageous in a non-fire-prone environment. Through this model, the researchers were able to show that fires can cause flammability traits to persist in a plant community, even if the environment does not make fires unavoidable—a phenomenon called fire feedback.

Because landscapes with intermediate dryness could be sta­ble as either fire-prone or fire-suppressing, the model showed that flammability traits could not just simply spread across a fire-suppressing landscape. The model presents two pos­sible origins of flammability traits: first, flammability traits originate in a semi-arid fire-prone patch and then spread to neighboring intermediate patches, facilitated by fire feedback; or second, the evolution of fire was driven by ancient atmo­spheric conditions, such as the oxygen-rich air of the Cre­taceous Period. The researchers thus demonstrated that fire feedback has played an undeniably significant role in the evo­lution of fire. This research has profound implications for re­gions such as the western United States, where wildfires have been raging for months now: the more fre­quent the fires, the more likely they are to happen again.