Incorporating trait-based mechanisms, alternative interaction modes and forbidden links increases the minimum trait dimensionality of ecological networks

Abstract

Trait-based approaches in direct intraspecific and interspecific interactions address proximate and evolutionary questions across biological systems. However, interest in particular questions or systems has led to specialised descriptions of how interactions occur. We propose a generalised description in which interactions can be: defined by goals (e.g. consumption, parasitism, pollination); charted systematically (with logic statements); and explained by performance inequalities (comparing traits of individuals). Consequently, goal failures ('forbidden links') are interaction outcomes; alternative strategies to goal success exist; and matching traits are reformulated as difference traits. To illustrate, we introduce a new network measure: minimum mechanistic dimensionality, the minimum number of traits for the mechanistic explanation of the outcomes. Our dimensionality offers alternative explanations for intransitive networks. We show that previous approaches underestimate the dimensionality of 658 published empirical ecological networks (animal dominance, food webs, pollination, parasitism, seed dispersal) by omitting concepts emerging from the framework (mechanistic perspective, trait-mediated goal failures, generalisation to alternative interaction strategies). Such underestimation can prevent models from generating networks at the interaction outcome level. The framework provides a common mechanistic basis for proximate and evolutionary questions, inspiring hypotheses and trait-based models of social network dynamics, antagonistic or mutualistic community assembly or invasion, and coevolution.

Incorporating alternative interaction modes, forbidden links and trait‐based mechanisms increases the minimum trait dimensionality of ecological networks

“…Data and code are deposited in the Dryad Digital Repository https:// doi.org/10.5061/dryad.dfn2z 34zp (Kiziridis et al, 2020).…”