OLM 6.4 Regulation of structured populations: an example
It has been noted in Ch6.4.3 (p.114) that the individuals of many taxa – insects, amphibians, and fish – may change their habitat, diet or predator during their life. This phenomenon is called the “ontogenetic niche shift”, whose consequence is that the survival probabilities or the fecundities of the individuals of different sizes or developmental stages may be sensitive to different regulating variables, and these regulating variables may be differentially impacted by the individuals at different stages. Thus, determining the niche of such populations requires considering their structures (Ch10.2.4, p.212). Primarily based on the work of Gary G. Mittelbach and his colleagues this section presents empirical results on the population regulation of sunfish species whose individuals become competitors due to their common predators. These studies are also examples of species niches being dependent on the actual niche space (Tbox 10.1, p.205): niches are affected by the presence or absence of the predator as well as by that of the competitor. We will show an example of modelling regulation in such a structured population in OLM 9.6.