Publication
Non-heritable variation in individual fitness adds stability to neutral theories in ecology and evolution
Publisher:
Cold Spring Harbor Laboratory
Date:
29-07-2018
DOI:
10.1101/379776
Abstract: Neutral theories in ecology 1 and evolution 2 contend that high ersity of natural communities and high rates of molecular evolution conform to models where in iduals have equal fitness and mutations have no effects. Demographic stochasticity makes community and population compositions inherently unstable under these models, with overall levels of ersity being maintained by random processes. This is in contrast with niche and adaptive theories which emphasize differences between species or genotypes as the key to their coexistence 3 . Here we show that non-heritable variation in in idual fitness within species or genotypes can stabilize coexistence without evoking niche differentiation. We construct two classes of mathematical models based on experimental evidence: (1) bacterial growth with variation in cell longevity 4,5 and (2) microbial transmission in a host population with variation in host susceptibility 6–11 . We find stable coexistence of 2 bacterial species in the first model under a single oscillating resource, and 3 or more in the second with independent distributions of host susceptibility to the various microbial species. We discuss the implications of these findings for the interpretation of common measures of relative fitness and for the maintenance of bio ersity.