"Survival of the FIttest? The Biodiversity Puzzle":
In many ecosystems, there is an overwhelming abundance of species. The challenge is how to reconcile this with evolutionary ideas of survival of the fittest and the competitive exclusion principle. In particular, Hubbell showed that statistics on species abundance appear consistent with a model of pure equality of species with no fitness differences.
We discuss this general issue and the statistical problem of calculating abundance distributions. We then point to a possible resolution: If the fitness lanscape has a quadratic maximum, there is an self-consistent effective equality among the many different species near the maximum, even though any species far from the maximum is selected against. This is not true in the more commonly studied linear fitness landscape.