Components of phylogenetic signal in trophic and mutualistic networks

Background/Question/Methods

The structure of food webs and mutualistic networks is related to the phylogeny of the interacting species. However, studies that test the presence of phylogenetic signal in ecological networks have focused on either trophic or mutualistic webs, and they have used different methodologies. Thus, a global assessment of the phylogenetic signal across network types and components of network structure has been precluded. We address this topic by fitting a data set of 60 mutualistic networks and food webs with the matching-centrality model. This model decomposes network architecture into contributions of matching and centrality, capturing the modular and nested, respectively, components of network structure. Our approach allows us to compare the magnitude of phylogenetic signal across network types, species sets (e.g., plants vs animals), and components of network architecture (e.g., matching vs centrality).

Results/Conclusions

Overall, we found a significant phylogenetic signal across network types, species sets, and components of network structure. However, there are contrasting differences in the frequency of phylogenetic signal across such groups. Regarding network types, phylogenetic signal is more abundant in food webs than mutualistic networks (encompassing as many as 100% of trophic webs, 79% of plant-pollinator webs, and 37% of seed-disperser webs). Regarding set types, species viewed as prey are more related to their phylogeny than species viewed as predators in food webs, while animals show stronger phylogenetic constraints than plants in mutualistic webs. Finally, regarding components of network structure, phylogenetic signal is more abundant in the matching than in the centrality contribution to network architecture.