Fig. 2.

Alternative niche concepts. (A) With Allee effects, the population persistence niche > the establishment niche. (B) With niche destruction, sites with a high initial growth rate are vulnerable to extinction, so lie outside of the population persistence niche, along these axes. In plant ecology, the term persistence niche is sometimes used to denote the role of individual adult survival through disturbances in permitting population persistence, for populations that have already established (90). I am using the term population persistence niche more broadly, to emphasize distinct aspects of the niche at the population rather than individual level. (C) The evolutionary niche. This figure (adapted from ref. 64) can describe many scenarios: (i) a species with geographic variation among niches of local populations; (ii) frames of a species over time, with niches wandering over its history within broad limits (bounded niche evolution); (iii) aggregate niche of a clade, with specialists descended from an ancestral generalist; and (iv) an adaptive radiation, where from an ancestral specialist (not shown) a clade collectively wanders through much more niche space than represented in any species.