Coevolution by different functional mechanisms modulates the structure and dynamics of antagonistic and mutualistic networks

Abstract

A central problem in the study of species interactions is to understand the underlying ecological and evolutionary mechanisms that shape and are shaped by trait evolution in interacting assemblages. The patterns of interaction among species (i.e. network structure) provide the pathways for evolution and coevolution, which are modulated by how traits affect individual fitness (i.e. functional mechanisms). Functional mechanisms, in turn, also affect the likelihood of an ecological interaction, shaping the structure of interaction networks. Here, we build adaptive network models to explore the potential role of coevolution by two functional mechanisms, trait matching and exploitation barrier, in driving trait evolution and the structure of interaction networks. We use these models to explore how different scenarios of coevolution and functional mechanisms reproduce the empirical network patterns observed in antagonistic and mutualistic interactions and affect trait evolution. Scenarios assuming coevolutionary feedback with a strong effect of functional mechanism better reproduce the empirical structure of networks. Antagonistic and mutualistic networks, however, are better explained by different functional mechanisms and the structure of antagonisms is better reproduced than that of mutualisms. Scenarios assuming coevolution by strong trait matching between interacting partners better explain the structure of antagonistic networks, whereas those assuming strong barrier effects better reproduce the structure of mutualistic networks. The dynamics resulting from the feedback between strong functional mechanisms and coevolution favor the stability of antagonisms and mutualisms. Selection favoring trait matching reduces temporal trait fluctuation and the magnitude of arms races in antagonisms, whereas selection due to exploitation barriers reduces temporal trait fluctuations in mutualisms. Our results indicate that coevolutionary models better reproduce the network structure of antagonisms than those of mutualisms and that different functional mechanisms may favor the persistence of antagonistic and mutualistic interacting assemblages.

The dispersal syndrome hypothesis: How animals shaped fruit traits, and how they did not

“…This can lead to increased specialization, and thus potentially co‐evolution. At the same time, strong trait‐matching has been shown to be a more important driver of antagonistic networks, while barriers such as size mismatch are more important in mutualistic networks (de Andreazzi, Astegiano, & Guimarães, 2020), which helps explain the strong empirical support for the evolution of fruit size (Table 1).…”

A White Noise Approach to Evolutionary Ecology

“…However, as biotic selection pushesx i away fromx j , the effect of competition with species j on the fitness of species i rapidly diminishes due to the Gaussian weights capturing a reduction in niche overlap. These Gaussian weights have been usefully employed to capture interaction preference in recent investigations of coevolution in mutualistic networks (de Andreazzi et al, 2019, Medeiros et al, 2018, Guimarães et al, 2017. The divergence ofx i andx j due to competition is referred to in the community ecology literature as character displacement (Brown and Wilson, 1956).…”

An individual‐based model for the eco‐evolutionary emergence of bipartite interaction networks

“…de Andreazzi et al . (2019) also recently showed that a strong effect of species trait values on the probability for two species to interact helps in explaining network structure, and in particular that trait matching fosters trait coevolution and helps in explaining the structure of antagonistic networks. Related to the trait‐based hypothesis is the observation that the non‐random structure of networks can emerge without being selected for when interaction strength is inherited from the parent species (the ‘network spandrel’ hypothesis Maynard et al ., 2018; Valverde et al ., 2018).…”

“…In de Andreazzi et al . (2019) investigated the effect of trait coevolution on network structure, with the number of both species and interactions fixed according to empirical networks. In Poisot and Stouffer (2016), the authors fitted a macroevolutionary model formalising the evolution of species interactions to empirical networks, and surprisingly did not detect major differences between antagonistic and mutualistic networks.…”