Nested diets: a novel pattern of individual-level resource use

Abstract

Many generalist populations may actually be composed of relatively specialist individuals. This ‘individual specialization’ may have important ecological and evolutionary implications. Although this phenomenon has been documented in more than one hundred taxa, it is still unclear how individuals within a population actually partition resources. Here we applied several methods based on network theory to investigate the intrapopulation patterns of resource use in the gracile mouse opossum Gracilinanus microtarsus. We found evidence of significant individual specialization in this species and that the diets of specialists are nested within the diets of generalists. This novel pattern is consistent with a recently proposed model of optimal foraging and implies strong asymmetry in the interactions among individuals of a population.

Complex-to-Predict Generational Shift between Nested and Clustered Organization of Individual Prey Networks in Digger Wasps

“…Our results reinforce the view that network-based approaches are useful at the individual level and that they can help to uncover peculiar patterns of resource use within populations [19], [23], [34]. Inter-individual variation ( E ) was detected in our aggregation in all three years studied, agreeing with previous results obtained for this species using slightly different, not network-based indices of prey overlap [17], [19].…”

“…Nevertheless, it is still not clear how the partitioning of resources among the members of a population is accomplished [23]. A number of factors have been proposed as potential causes for inter-individual diet variation patterns, including forager's previous experience [24], neurologic constraints [25], [26], body size variation [16], [18], patchiness of the environment or fidelity to a foraging area [20], [27], [28], cultural transmission or social learning of foraging behaviours [29]–[33], frequency-dependent selection [9], or intra-specific competition [22], [34].…”

Foraging strategies of a generalist marine predator inhabiting a dynamic environment

“…Differences in individual behavioral consistency may have been driven by prey availability or individual foraging success, with individuals switching foraging strategies when they were unsuccessful in finding sufficient resources on their previous trip. Alternatively, this variability may be an indication that individual California sea lions may adopt either a generalist or specialist foraging strategy, which has been documented for both marine and terrestrial species (Araújo et al 2010;Tinker et al 2012;Cantor et al 2013;Kernaléguen et al 2016). Given that sea lions were only tracked across a 2-month period, we cannot make conclusions about whether these individual behavioral patterns may persist across longer temporal scales.…”

Food webs: reconciling the structure and function of biodiversity

“…Incorporating individual variability in body size of animals into food web models has already been discussed above. However, individual-to-individual variability in resource use can also be seen in a number of groups, including individual niche specialists in trees [46] and individual 'specialists' and 'generalists' within rodent populations [47]. Incorporating these complexities into food web models will be challenging, but there are clear avenues for future research.…”