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| Modularity is a recurrent and important property of bipartite ecological networks. Although wellresolved
ecological networks describe interaction frequencies between species pairs, modularity of
bipartite networks has been analysed only on the basis of binary presence–absence data. We
employ a new algorithm to detect modularity in weighted bipartite networks in a global analysis
of avian seed-dispersal networks. We define roles of species, such as connector values, for
weighted and binary networks and associate them with avian species traits and phylogeny. The
weighted, but not binary, analysis identified a positive relationship between climatic seasonality
and modularity, whereas past climate stability and phylogenetic signal were only weakly related to
modularity. Connector values were associated with foraging behaviour and were phylogenetically
conserved. The weighted modularity analysis demonstrates the dominating impact of ecological
factors on the structure of seed-dispersal networks, but also underscores the relevance of evolutionary
history in shaping species roles in ecological communities. | |
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