Coexistence and the Strength of Stabilization
Plots of fitness equivalence (\(\frac{R_{\max,j}}{R_{\max,i}}\)) overOij showed that almost all species pairs have
sufficiently similar fitness to satisfy the coexistence conditions
expressed by equation 1, even as Oij approaches 1
(Fig. 3a). Only 18 of 166 species pairs fell outside the zone for
coexistence (14 when R max was estimated using
allometric regression; supplementary Fig. S5). A similar pattern was
found when comparing one species j with the average of all others
(Fig. 3b). There was no evident trend of a change in fitness
equivalences along the overlap gradient, implying that most species (or
species pairs) have sufficiently similar fitness that coexistence is
stable for virtually any level of niche overlap. The strength of the
stabilizing effect of niche differences is such that, in most cases,
niche overlaps were between 50 and 100% smaller than the minimum
necessary to enable coexistence (Figs 3c and d). The median of the
percentage difference between observed and minimum permissible overlap
was high (0.73), with an interquartile range from 0.40 to 0.95.