seems to start from assumptions that are clearly wrong. It seems like throwing ecology away.

There have also been challenges to the theory’s science. In particular, several teams have claimed that there is more structure in nature than neutral ecology can account for, that who lives with who is predictable, suggesting that the species in a place are evolved to match the conditions there and are not a random subset of the whole. Neutral ecology also seems best at predicting patterns in diversity at intermediate scales, from a few hundred square meters to tens of square kilometers. On larger scales, environmental differences become important—just as a plant from the tundra would not survive in a desert. On smaller scales, interactions between individuals do seem to have an effect on who can live with whom, and ecologically similar species are less likely to be found very close together.

Experiments can test whether plants live where they do through chance or because they have found their niche. You just move the plant from its wild home to somewhere else. In a world of niches, residents will be better off and migrants will struggle. In a neutral world, travel will be easier. A team led by Graham Bell, an ecologist who developed models of neutral ecology independently of Hubbell, found that plants were quite happy to be moved around Canadian forests. There was no sign that they had a strong preference for a particular environment or set of neighbors. And neutral ecology makes predictions about time as well as space: Widespread and abundant species are more likely to be old, because it takes a long time to become common relying on dumb luck alone. Rare species are more likely to have evolved recently. Comparing DNA, which gives clues about how long ago a species came into being, might answer this question. A bit like Kleiber’s rule for body size and metabolic rate, the real world is bound to deviate from neutral ecology’s predictions: how much it deviates, and how, will show what needs to be explained by other means, such as competition, and what doesn’t.

Patterns or Explanations?

There is also the issue of whether a mathematical model that reproduces a natural pattern, however uncanny its accuracy, really explains



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