Individual-based networks reveal the highly skewed interactions of a frugivore mutualist with individual plants in a diverse community
Data files
Aug 27, 2021 version files 267.23 KB
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e.rubriventer_frugivory_data_2018_DRYAD.csv
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frugivory_plot_phenology_DRYAD.csv
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indiv_networks_DRYAD_Readme.txt
Abstract
While plant-animal interactions occur fundamentally at the individual level, the bulk of research examining the mechanisms that drive interaction patterns has focused on the species or population level. In seed-dispersal mutualisms between frugivores and plants, little is known about the role of space and individual-level variation among plants in structuring patterns of frugivore foraging and, thus, seed dispersal in a plant community. Here we use an animal perspective to examine how space and variation between individual plants affect movement and visitation by frugivores foraging on individual fruiting plants. To do this, we used a spatially explicit network approach informed by observations of the movement and foraging of a frugivorous lemur species (Eulemur rubriventer) amongst individual plants in a diverse plant community in Madagascar. The resulting hierarchical networks, in which a few individual plants received the bulk of the interactions, demonstrated how a generalist frugivore species could act as an individual-plant specialist within a plant community. The few individual plants that dominated interactions with the lemurs shaped the modular spatial structure of frugivory interactions in the community and facilitated visitation to near neighbors. This interaction structure was primarily driven by extrinsic factors, as lemur movements among plants were significantly influenced by the individual plant’s spatial position and the species richness of fruiting plants in its immediate neighborhood. Individual plants in central spatial locations, with a rich fruiting neighborhood and large fruit crops, received the most visits. The observed drastic inequality in the interactions of a generalist frugivore within a highly diverse plant community highlights the importance of considering individual-level variation for essential ecosystem processes, such as seed dispersal.
Methods
Data include a record of direct observations of lemur foraging for fruit amongst individually tagged trees in the forests of Ranomafana National Park. The data include the date, time, gps location, plant species and plant individual tag for each frugivory event. The observations were done on two lemur groups in the Valohoaka site in the intact forest of RNP over the months of May-August 2018. The data also include surveys of the fruiting neigborhoods (within 10 m) of each plant in which a foraging event took place. Records include the data of the survey, that ID of the focal tree and the species and fruit crop (Quantified by a catergorical variable 1-5) of each fruiting tree.