Robert Ricklefs gave the American Society of Naturalists‘ Presidential Address today at Evolution 2011. For me, this was one of the high points of the entire conference. In a meeting where ecologists and tropical biologists were fairly thin on the ground, it was great to see someone speak who had such standing, not only as an ecologist, but also someone who had done some of his best work on the biogeography of the insular Caribbean.
Ricklefs talked about what it meant to be a “naturalist”. Naturalists and natural history have gone out of fashion in the last half century. Naturalists were Victorian field biologists, especially the amateur biologists and explorers who played such an important role in the early development of fields like ecology, evolution and taxonomy. But as growing academic disciplines in the second half of the twentieth century, these fields felt the need to divorce themselves from their antecedents in “natural history” and claim their place as rigorous academic disciplines. In his memoir Naturalist, E.O. Wilson spoke of some of the challenges that organismal biologists faced in the early years of the age of DNA, when they were labelled ‘stamp collectors’ and portrayed as a field being superseded by molecular biologists. It was against that backdrop that the fields of ecology, evolution and systematics transformed themselves into hard, quantitative scientific disciplines in the second half of the twentieth century. Modern systematics is about building consensus trees based on genetic data, and evolutionary biologists talk about SNPs and haplotypes. You can be an organismal biologist who has never seen your organism in the wild.
It was against a backdrop such as this that Ricklefs presented his talk. Direct observations of nature – direct experience of nature – is important for the progress of ecology and evolutionary biology. Most people realise, at least on some level, that observations of nature are an important means by which hypotheses can be generated. Broad theories and models of how the world work also have their roots in observations of the natural world. But, as Ricklefs pointed out, we also need to test our theories and models against nature, ensure that our explanations aren’t only internally coherent and logical, but that they also work when presented with the real world.
In addition to his own work on taxon cycles in Caribbean bird species, Ricklefs also discussed Steve Hubbell’s Unified Neutral Theory of Biodiversity and Biogeography. Hubbell’s neutral theory is a rather interesting idea. in essence, it suggests that tree species are competitively neutral, and that species diversity in tropical forests is maintained by a a mixture of random drift and speciation. Ricklefs expressed the opinion that Hubbell’s neutral theory, which has been around for a decade, probably has another decade before it fades into obscurity, as these things tend to do in ecology. The flaws in the neutral theory, he said, are seen when the theory is confronted with data.