The impacts of geographic and environmental range size on species centrality in floral visitation networks
Baltimore skyline photo by Brendan Beale on UnsplashAbstract
In mutualistic interaction networks, a species’ role in a given network can be described using several mathematical properties. Node centrality—a suite of measures describing how connected a given node is to the rest of the network—is a commonly studied metric as removing highly central species from a network is likely to have outsized impacts on biotic communities. Understanding the drivers of species’ centrality in floral visitation networks is crucial, as declines in pollinator abundance and diversity threaten to reduce pollination services globally. One potential driver of species centrality is the size of its range. We hypothesize that, at the level of the metaweb (the global set of observed interactions) species centrality in mutualistic networks would positively scale with both environmental and geographic range size, as wide-ranging species exhibit turnover in interaction partners across space or environments. We also expected this positive relationship to hold in the context of local interaction networks as well, as broad ranges may be associated with generalist partner preferences. Here we test these expectations by characterizing these associations in floral visitation networks. We used large-scale occurrence datasets to calculate the geographic and environmental ranges occupied by 2,703 plant and 4,305 floral visitor species, distributed across 99 globally distributed floral-visitation networks comprising 31,677 unique interactions.
