Individual–resource networks reveal distinct fruit preferences of selective individuals from a generalist population of the Helmeted Manakin

Abstract

Ecological studies traditionally assume that generalist populations are homogeneous in the use of food resources, but empirical evidence supports that intraspecific differences in morphology, physiology and behaviour affect foraging decisions and promote diet variation among individuals. Furthermore, the temporal availability of resources may shape the dynamics of population trophic niche, which ultimately depends on individual niches. In this study, we investigated the seasonal changes in individual‐based networks between the Helmeted Manakin Antilophia galeata, a generalist frugivorous bird, and fruiting plants, following theoretical models of interindividual diet variation based on the Optimal Diet Theory. Selective individuals were the majority of the generalist population of the Helmeted Manakin. Our results suggest that the structure of the individual‐resource networks varied seasonally. We found that modularity was higher than expected by chance in the wet season, when fruit availability was also higher. In the dry season, modules disappeared and the network became more nested. These findings are consistent with the Distinct Preference Model of diet variation. We suggest that downscaling ecological networks to the individual level may reveal emergent properties that, albeit existent, are not evident in species–resources networks.

Intraspecific differences in seed dispersal caused by differences in social rank and mediated by food availability

“…The importance of density-dependence is well established in the seed dispersal literature, mainly focusing on the effects of temporal changes in food availability 2,3,45 . We and recent studies 7,46 have found that the temporal availability of fruit influences frugivore choices, which in turn causes intraspecific variation in seed dispersal parameters. Intraspecific variability in both plants and animals does not simply add noise to systems, but alters dispersal processes and patterns with consequences for plant demography, communities, evolution and responses to anthropogenic changes; by reducing this variability to an average value, important details on the seed dispersal capacity and resilience of animals has been lost [5][6][7]46 .…”

“…We and recent studies 7,46 have found that the temporal availability of fruit influences frugivore choices, which in turn causes intraspecific variation in seed dispersal parameters. Intraspecific variability in both plants and animals does not simply add noise to systems, but alters dispersal processes and patterns with consequences for plant demography, communities, evolution and responses to anthropogenic changes; by reducing this variability to an average value, important details on the seed dispersal capacity and resilience of animals has been lost [5][6][7]46 . Individuals within a population respond to fruit abundance, which might alter the extent and direction of intraspecific variation within populations.…”

Seasonal and Interspecific Variation in Frugivory by a Mixed Resident-Migrant Overwintering Songbird Community

“…It is possible that this disparity reflects interannual variation in fruit availability, which has been documented at our study site [39,68]. However, variation in resource use at the community and population levels may also be the result of distinct preferences among individuals, which have been observed to vary seasonally in some cases [89,90]. Thus, the high degree of variation in our estimates of diet, as well as variation among years may indicate the influence of individual preferences and possibly resource partitioning among individuals.…”

Environmental Stress and Fluctuating Asymmetry in Antilophia Galeata, Myiothlypis Flaveola and Basileuterus Culicivorus in Brazilian Savanna

“…Antilophia galeata consumes fruits mainly during fl ight (Marini 1992, Silva & Melo 2011, Pires & Melo 2019. Flight maneuvers often wear out the wings by putting them in more contact with the environment, suff ering the infl uence of stressors that makes it diffi cult to stabilize the character (Gonçalves & Melo 2012).…”