The Interface of Ecology and Evolution During the Formation of the Science of Ecology

Abstract

The Ecological Society of America formed at a time when ecology and evolutionary biology were developing as almost completely separate disciplines. The schism had occurred near the turn of the century. Prior to 1900, ecological research, under the guise of natural history, provided some of the most important evidence for evolution in general and natural selection in particular. But as evolutionary biologists became focused on the genetic mechanisms of heredity in the early decades of the 20th century, ecologists become focused on non-evolutionary aspects of physiology, population biology, and community structure. The intellectual divide between ecology and evolutionary biology became so great that Charles Elton, in his 1925 book on Animal Ecology, felt that he needed to explain why he had devoted a chapter to evolution in a book on ecology. The eventual intertwining of ecology and evolutionary biology is historically complex, and it took almost half a century to cement the connections between these disciplines. Few of those connections appeared in the early issues of Ecology, which began publication in 1920. A search through those early issues shows the depth of the divide. In fact, Barrington Moore's ESA presidential address that year, which he called The Scope of Ecology, emphasized the divide. Published as the lead article for volume 1, issue 1, Barrington wrote. "All life is controlled by two great forces, heredity and environment, and ecology is the science dealing with the environment." Links to evolutionary processes remained indirect for years to come within the pages of the journal. Some occasional articles, though, noted how ecology may help interpret evolutionary history, such as Frank Collins Baker's article in volume 2 on the importance of ecology in the interpretation of fossil faunas. Against this background, Joseph Grinnell's 1924 paper in Ecology, entitled Geography and Evolution, stands out for its forward thinking. Grinnell is one of the early intellectual heroes of ecology. Many biologists remember him primarily for his characterization of the concept of the niche, but his thinking ranged more broadly and deeply throughout the diversity and diversification of life across environments. He rarely wrote directly about conceptual topics, and much of his work focused on describing geographic variation in species and assemblages of species. In his 1924 article, though, he wrote about biogeography and evolution for an ecological journal. His article discussed the ways in which isolation, ecology, and adaptation are likely to affect speciation. He wrote, "In my interpretation, isolation [among "stocks" or populations] alone has not sufficed; stocks, in vertebrates at least, must have been set apart under different ecological conditions for isolation to be effective." These are early musings on what we now consider ecological speciation. He goes further by considering the aspects of environments that may be important in driving population divergence and speciation. After considering the effects of different physical environments,