Evolutionary history structures the frequency of plant–hawkmoth interactions, beyond its effect through ecological traits

Abstract

Multiple processes influence species interactions and may shape the structure of ecological networks. Although evolutionary processes may influence interactions via shared inherited traits, their importance in comparison to contemporary ecological processes remains underappreciated. Here, we investigated how the evolutionary isolation of hawkmoths and plants is associated with interaction frequencies and the emergence of modularity in a mutualistic interaction network from Pampa grasslands. Further, we evaluated the importance of these effects in relation to morphological matching, phenological overlap, and relative abundances. We found that higher interaction frequencies occur for hawkmoths with intermediate evolutionary isolation and for plants with low evolutionary isolation, besides increasing with morphological matching and phenological overlap of partners. It suggests that intermediately isolated hawkmoths could achieve a balance between generalization and specialization, increasing interaction frequencies, and that flowers of closely related plant species are visited more frequently, presumably due to shared pollinator-attracting traits. Modules composition indicates that interactions inside modules are at least in part influenced by hawkmoth phylogeny, especially on the genera level. Also, hawkmoths’ ecological traits differ between modules, but this difference is given by interaction frequencies and not by hawkmoths’ composition itself. Our study illustrates how evolutionary history contributes to shaping plant–hawkmoth interaction frequencies through ecological traits and beyond them and that the emergence of modules may be linked to additional processes related to community assembly.