The Importance of Rare Events

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Ryan Chisholm, a theoretical ecologist and professor at the National University of Singapore who studies tropical tree distribution, agrees that Kalyuzhny’s findings fit with previous work on CNDD. He suggests, however, that the models might be underestimating how far dispersal mechanisms can spread seeds. If far-spreading events are rare, for example, they could be hard to see in the seed-trap data. And if seeds are carried farther than researchers realize, that could account for the more spread-out clumps of trees in the forests without need for repulsion.


I repulse my neighbors, and they repulse their neighbors, and they repulse Phone Number List their neighbors… The forest is a messy crystal. Michael Kalyuzhny, Hebrew University of Jerusalem “What they are saying here is that according to their dispersal limitation model, the patterns they observe are impossible,” Chisholm said. “I would say we don’t know enough to say that yet.” Rare events have been important in the dispersal of species of all kinds: Monkeys, for example, are thought to have arrived in the Americas from Africa on rafts of vegetation, a stupendously unlikely event that nevertheless had significant consequences.



“Occasionally you’re going to get that one bird that carries the seed very far, or gets caught by the wind and goes for an adventure,” Chisholm said. He points out that seed distribution seems to have a very fat tail at the end — it’s not a bell curve, as nonexperts might think — and that we don’t know its shape well enough yet. He points out that we don’t know the shape of the curve for seed distribution well enough yet —it’s not a simple bell curve, as nonexperts might think, because it seems to have a very “fat tail” at the end.