Ecological drivers of intrapopulation niche variation

Background/Question/Methods

There is extensive evidence that some species of ecological generalists, which use a wide diversity of resources, are in fact heterogeneous collections of relatively specialized individuals. This within-population variation, or ‘‘individual specialization,’’ is a key requirement for frequency-dependent interactions that may drive a variety of types of evolutionary diversification and may influence the population dynamics and ecological interactions of species. Consequently, it is important to understand when individual specialization is likely to be strong or weak. In this talk I will review current theoretical and empirical work and ask what are the ecological drivers of intra-population niche partitioning.

Results/Conclusions

Empirical work (experiments and comparative studies) mainly confirms the theoretical expectations that the magnitude of among-individual diet variation depends on the level of intra- and interspecific competition, ecological opportunity and predation. Specifically, it has been shown that increased intra-specific competition is increasing among-individual diet variation whereas inter-specific competition is reducing among-individual diet variation. Generally, the effect on among-individual diet variation from competition (intra and inter) comes from resource competition. Predation on the other hand can limit among-individual diet variation by restricting its prey to certain habitats or resources. These results show that among-individual diet variation can be affected by a suite of ecological factors in nature, but the interactions between these factors (competition and predation) is poorly investigated. Furthermore, whether greater among-individual diet variation translates into greater genetic variation, ability to evolve, or ecological stability remains to be determined.