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In the Beat of a Heart: Life, Energy, and the Unity of Nature
works and helped found the field of ecosystem ecology. But Lindemann never saw it published: While it was in review, he died of liver disease, at age 26.
The Paradox of Diversity
So biodiversity is not a product of long food chains. Most diversity is found within the levels of food webs rather than between them. The 1,500 orchid species in Costa Rica all occupy the same level of the web, as do the thousands of herbivorous insects that feed on them, or the birds and lizards that eat the insects, and the birds of prey and cats that catch the birds. This struck Hutchinson as paradoxical. By the late 1950s, lab and field experiments, on microbes in a jar or grasses in a plot, had already shown ecologists that, if two species were made to fight over the same suite of resources, one would always eliminate the other. Yet diversity is ubiquitous. Seemingly featureless places, such as prairies, invariably contain many species of grasses and herbs. Plankton puzzled Hutchinson most of all. The open water of a lake seems a homogenous environment, like a giant lab flask, yet somehow hundreds of species are able to share it. It takes a lot of effort to minimize the number of species in a place, as gardeners and farmers know.
Besides posing a puzzle, the lab experiments gave a clue as to what might be going on. The outcome of contests depended on the conditions in the arena—tweaking the temperature, or the amount of nitrogen in the soil, changed which species won. This variability seemed to open up more job opportunities for species, more potential specializations. Species can also vary by when they breed, the temperature they prefer, whether they grow best in shady conditions or sunny, whether they are active at night or day, and in many other ways. A few years before his encounter with Santa Rosalia, Hutchinson devised a way of thinking about a species’ place in nature—its niche. He saw the niche as a set of coordinates specifying each species’ lifestyle choices and how it fit into biological and environmental space. One axis might represent the temperature range a species could tolerate. Another might be the range of food items that species would eat. Tree-dwelling birds could be defined by the height at which they built their nests.