|Dr John Whitfield
Science writer, author and blogger
The greatest innovation in ecology is the concept of the niche, as developed by Evelyn Hutchinson in the late 1950s. An ecological niche is like a cross between a job and an address. It describes where a species lives, in terms of, say, the temperatures it can tolerate, or the amount of water it needs, and also what it does - the food it eats, whether it migrates or hibernates, and so on.
Hutchinson, who was born in the UK but spent most of his career in the US, proposed that niches can explain biodiversity - why there are, say, 50-odd species of butterfly in the United Kingdom, and not 5000, or five. Every species, he suggested, has a unique niche, and if two species are too similar, one will drive the other extinct. In this picture, diversity is the result of species evolving to occupy different niches: bats and birds both eat insects, for example, but do so at different times; giraffes and gazelles both browse leaves, but at different heights on the tree. The total amount of resources in an ecosystem - the size of the niche space - and the sizes of the differences between species controls what can live there.
Ecologists still wrestle with niche theory, and have suggested many other possible explanations for the origin and maintenance of biodiversity. Some environments seem too homogenous for niches to explain their diversity: Hutchinson pointed to the many species of plankton that can coexist in a single lake. Others seem too diverse - is there really a unique niche for each of the several hundred tree species in a single hectare of rainforest? But in formulating the problem, and suggesting a possible answer, Hutchinson was one of the main forces in moving ecology from being a science that described nature to one that tried to explain it.
He was also a brilliant mentor, inspiring many students who went on to become influential researchers, and acting as midwife to a golden age of his science.
Book suggestion: ‘In the Beat of a Heart: Life, Energy, and the Unity of Nature’ (Joseph Henry Press) http://www.inthebeatofaheart.com gentraso.blogspot.com In the Beat of a Heart: Life, Energy, and the Unity of Nature (Joseph Henry Press).