Seed‐dispersal networks are more specialized in the Neotropics than in the Afrotropics

Abstract

Aim Biogeographical comparisons of interaction networks help to elucidate differences in ecological communities and ecosystem functioning at large scales. Neotropical ecosystems have higher diversity and a different composition of frugivores and fleshy‐fruited plants compared with Afrotropical systems, but a lack of intercontinental comparisons limits understanding of (a) whether plant–frugivore networks are structured in a similar manner, and (b) whether the same species traits define the roles of animals across continents. Location Afrotropics and Neotropics. Time period 1977–2015. Taxa Fleshy‐fruited plants and frugivorous vertebrates. Methods We compiled a dataset comprising 17 Afrotropical and 48 Neotropical weighted seed‐dispersal networks quantifying frugivory interactions between 1,091 fleshy‐fruited plant and 665 animal species, comprising in total 8,251 interaction links between plants and animals. In addition, we compiled information on the body mass of animals and their degree of frugivory. We compared four standard network‐level metrics related to interaction diversity and specialization, accounting for differences related to sampling effort and network location. Furthermore, we tested whether animal traits (body mass, degree of frugivory) differed between continents, whether these traits were related to the network roles of species and whether these relationships varied between continents. Results We found significant structural differences in networks between continents. Overall, Neotropical networks were less nested and more specialized than Afrotropical networks. At the species level, a higher body mass and degree of frugivory were associated with an increasing diversity of plant partners. Specialization of frugivores increased with the degree of frugivory, but only in the Neotropics. Main conclusions Our findings show that Afrotropical networks have a greater overlap in plant partners among vertebrate frugivores than the more diverse networks in the Neotropics that are characterized by a greater niche partitioning. Hence, the loss of frugivore species could have stronger impacts on ecosystem functioning in the more specialized Neotropical communities compared with the more generalized Afrotropical communities.

Similar composition of functional roles in Andean seed‐dispersal networks, despite high species and interaction turnover

“…For instance, the approach can be used to describe species' functions that are difficult to assess indirectly via species' traits (e.g., physiological and metabolic processes) or to describe the environmental conditions under which species can exist, i.e., their Grinnellian niches (Dehling and Stouffer 2018). Taking into account species' functional roles could prove to be especially useful for comparisons of networks and ecological processes between sites that have few or no species in common, e.g., in comparisons on large spatial scales, across habitats, and in regional meta-networks (Araujo et al 2018, Dugger et al 2019). However, while the method we used allows the direct comparison of all species that contribute to an ecological process, independent of their taxonomic relationships, most networks have so far been sampled for single taxa in the upper trophic level (e.g., bird-plant or bat-plant networks).…”

From structure to function in mutualistic interaction networks: Topologically important frugivores have greater potential as seed dispersers

“…To control the effect of statistical non-independence due to data for similar taxa in the two localities, we included (as a random effect) frugivore taxonomic identity, which included, with nested categories, species, genus and family (e.g. Dugger et al, 2019). The proportion of variance explained by the fixed effects, and by the combination of the fixed and random effects, was estimated based on the marginal and conditional R 2 values, respectively (Nakagawa & Schielzeth, 2013).…”

Plants on the Move: Hitch-Hiking With Ungulates Distributes Diaspores Across Landscapes

“…In plant dispersal networks, diaspores produced by the parent plant can be dispersed through endozoochory by different co-occurring vectors. These networks have been established principally for frugivory and endozoochory (Dugger et al, 2018;Miguel et al, 2018). Fedriani and Delibes (2009) studied the role of different mammals (e.g., wild pig; red deer; badger, Meles meles and red fox, Vulpes vulpes) dispersing the Iberian pear (Pyrus bourgaeana).…”