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This article is a little different from the fare you’re used to getting from me: it’s for SIAM News, which is the glossy magazine for members of the Society for Industrial and Applied Mathematics (SIAM). The audience for this magazine, in other words, is professional mathematicians and related researchers working in a wide variety of fields. While the article contains equations, I wrote it to be understandable even if you skip over the math.
Competitive Adaptation Prevents Species from Eradicating Each Other
For SIAM News:
Evolution is frequently rough and unforgiving; individuals within a species compete for food, reproductive partners, or other resources. Species fight each other for survival, especially when preying on one another.
Mathematical biologists often simplify these dynamics to predator versus prey. Real-world populations of predator and prey species within a given ecosystem cycle between booms and busts. In various cases, multiple species—including both predators and prey—coexist with similar diets. For example, a cubic meter of seawater can harbor several species of plankton, consisting of tiny plants and animals (see Figure 1).
One would naively expect reproductive success (more offspring) or competitive performance (eating more than your neighbor) to lead to one species’ domination. But that does not occur. While many of these organisms consume the same food, one species does not out-eat the others; the plankton swarm’s overall diversity remains fairly constant. Biologists refer to this phenomenon as the “paradox of the plankton” or the “biodiversity paradox,” among similar terms.