The scaling of trophic specialization in interaction networks across
levels of organization
Abstract
Natural ecosystems are characterized by a specialization pattern where
few species are common, while many others are rare. In ecological
networks involving biotic interactions, specialization operates as a
continuum at individual, species, and network level. Ecological theory
predicts that specialization can be primarily explained by ecological
and evolutionary factors. However, we still do not understand how
trophic specialization scales from individual- to the network-based
level. This question has been addressed by the emerging research program
on the macroecology of biotic interactions, which focuses on ecological
network and macroecological theory to investigate biotic interaction
patterns along environmental and geographical gradients. Based on the
ecological and evolutionary traits of interacting species, the study of
local networks traditionally focused on interspecific networks or
individual species as independent ecological units. Instead, the
macroecological perspective requires a shift towards assessing network
variation across ecological gradients, while also accounting for
different temporal scales (minutes, hours, days, and years), spatial
scales (local, regional, and global), and levels of network organization
(individuals, species, and assemblages). Despite the feasibility of
scaling data, the variation across individual, species and assemblage
levels in relation to network organization and geographic and
environmental gradients remains unknown. Understanding the mechanisms
driving species roles across different network scales is crucial for
addressing knowledge gaps, which in turn requires synthesizing and
clarifying the available information on these concepts. Thus, in this
study we aim to examine the factors shaping trophic specialization at
different levels of network organization and to review recent advances,
outcomes, and future directions of the field of macroecology of biotic
interactions related to specialization. By unraveling the factors and
mechanisms that explain the role of each species across different
network scales, we shed light on the processes underlying the assembling
of natural communities and offer valuable insights into specialization
gradients.