Insights into the assembly rules of a continent-wide multilayer network

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Abstract

How are ecological systems assembled? Identifying common structural patterns within complex networks of interacting species has been a major challenge in ecology, but researchers have focused primarily on single interaction types aggregating in space or time. Here, we shed light on the assembly rules of a multilayer network formed by frugivory and nectarivory interactions between bats and plants in the Neotropics. By harnessing a conceptual framework known as the integrative hypothesis of specialization, our results suggest that phylogenetic constraints separate species into different layers and shape the network’s modules. Then, the network shifts to a nested structure within its modules where interactions are mainly structured by geographic co-occurrence. Finally, organismal traits related to consuming fruits or nectar determine which bat species are central or peripheral to the network. Our results provide insights into how different processes contribute to the assemblage of ecological systems at different levels of organization, resulting in a compound network topology.

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Fig. 1: The bat–plant multilayer network.
Fig. 2: Matrices evidencing compound topology.
Fig. 3: Centrality of bat species across layers.
Fig. 4: Influence of organismal traits on centrality.

Data availability

Raw network data are freely available on GitHub via Zenodo: https://doi.org/10.5281/zenodo.1487572.

Code availability

Visualization codes are freely available on GitHub via Zenodo: https://doi.org/10.5281/zenodo.1487572.

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Acknowledgements

We are deeply grateful to all naturalists who carried out fieldwork in the Neotropics over several decades and collected the information used to build our dataset. J. Bronstein gave invaluable suggestions for an early draft of this study. P. Guimarães Jr, T. Quental and T. Lewinsohn discussed with us the assembly rules of interaction networks. P. Jordano, C. Dormann and K. Ognyanova gave us invaluable tips on how to analyse and draw networks in R. M. White and the StackOverflow community helped us build the model used in the latent variable analysis. M.A.R.M. was funded by the São Paulo Research Foundation (FAPESP, no. 2018/20695-7), Research Dean of the University of São Paulo (PRP-USP, no. 18.1.660.41.7), the Brazilian Council for Scientific and Technological Development (CNPq, no. 302700/2016-1), Minas Gerais Research Foundation (FAPEMIG, no. PPM-00324-15), and the Alexander von Humboldt Foundation (AvH, no. 3.4-8151/15037). G.M.F. and R.B.P.P. received scholarships from the Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES) and CNPq through the Graduate School in Ecology of the Federal University of Minas Gerais. R.L.M. received scholarships from FAPESP (nos. 2015/17739-4 and 2017/01816-0). S.E.S. was supported by the National Science Foundation (no. NSF-1456375). N.L. received a scholarship from CNPq and The World Academy of Sciences (no. 312518/2015-3) and grants from CAPES (no. 88887.308754/2018-00) and Pernambuco Research Foundation (FACEPE, no. BCT-0426-1.05/18). F.A.R. acknowledges CNPq (no. 307974/2013-8) and FAPESP (nos. 17/50144-0 and 16/25682-5) for the financial support given for his research, and the Leverhulme Trust for the Visiting Professorship provided.

Author information

M.A.R.M. conceived the project. The first version of the working question, hypothesis and predictions was created by M.A.R.M. together with R.B.P.P. and G.M.F., and all authors contributed to improving the logical argument of the study. C.G. and M.T. acquired the literature data and field data used to build the dataset of bat–plant interactions, and M.A.R.M. updated the dataset. S.E.S. reconstructed the bat phylogeny. S.E.S. and R.D.S. built the dataset on bat morphology and performance. F.A.R. and N.L. developed the new multilayer version of the centrality metrics. M.A.R.M., R.L.M., R.B.P.P., G.M.F., F.A.R. and N.L. performed tasks related to data analysis and coding in R and Python. The first draft of the manuscript was written by M.A.R.M., R.B.P.P., G.M.F. and R.L.M., and all authors contributed to editing the text.

Correspondence to Marco A. R. Mello.

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Mello, M.A.R., Felix, G.M., Pinheiro, R.B.P. et al. Insights into the assembly rules of a continent-wide multilayer network. Nat Ecol Evol 3, 1525–1532 (2019) doi:10.1038/s41559-019-1002-3

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