Evolutionary theory has long held that natural selection largely operates at the level of individuals. Findings from Northern Arizona University researchers, recently published in the Annual Review of Ecology, Evolution, and Systematics, suggest that selection can also occur at multiple levels to shape whole communities. This multi-level selection arises from the interactions of key species that cascade to alter communities and ecosystems.
For example, unraveling the evolution of complex forest communities that are home to thousands of interacting species is crucial to understanding the fundamental principles that organize life on Earth. Genetically based traits, such as tree chemistry and leaf flush or bud set, often drive interactions among species in these communities. These types of complex interactions require a more elaborate conceptual framework than individual selection alone.