Allometric Trophic Networks From Individuals to Socio-Ecosystems: Consumer–Resource Theory of the Ecological Elephant in the Room

Abstract

A well-known parable is that of the blind men studying an elephant each of which assert the elephant is the part they first hold in their hands, e.g., "rope!" says the tail holder while the leg holder asserts "tree!" The various subdisciplines of ecology appear similar in that we each engage in our enthusiastic but at least somewhat myopic study with remarkably limited agreement or even discussion about the overall system which we all study. Allometric trophic network (ATN) theory offers a path out of this dilemma by integrating across scales, taxa, habitats and organizational levels from physiology to ecosystems based on consumer-resource interactions among co-existing organisms. The network architecture and the metabolic and behavioral processes that determine the structure and dynamics of these interactions form the first principles of ATN theory, which in turn provides a synthetic overview and powerfully predictive framework for ecology from organisms to ecosystems. Beyond ecology, ATN theory also synthesizes eco-evolutionary and socio-ecological research still largely based on consumer-resource mechanisms but respectively integrated with different processes including natural selection and market mechanisms. This paper briefly describes foundations, advances, and future directions of ATN theory including predicting an ecosystem's phenotype from its community's genotype in order to accelerate more predictive and unified understanding of the complex systems studied by ecologists and other environmental scientists.

Body Size Dependent Dispersal Influences Stability in Heterogeneous Metacommunities

“…Following [5,7,10,11], we assigned body sizes assuming that the normalized mass of each species scales with their trophic position , as = . For reported results, normalized producer body sizes are uniformly set to one while = 42.…”

“…In contrast to randomly-assembled communities, an emerging focus in modern biodiversity theory is on the non-random structural features of ecological systems that impart stability [4,8,9]. For communities organized around feeding relationships (i.e., food webs), two types of structure receiving extensive attention are allometric hierarchies, where larger species mostly eat smaller ones and populations experience other demographic rates dependent on body-size [5,10,11]; and dispersal among spatially discrete habitats [12,13,14,15]. Body size-based food web topologies and allometric scaling of population demographic rates have both shown to be stabilizing for models of trophic interactions [5,6,10,16,17].…”

Flexible foraging behaviour increases predator vulnerability to climate change

“…Thus, we need accurate descriptions of how warming changes species' interactions to predict how ecosystems will respond to rising temperatures (Binzer et al 2016, Gauzens et al 2020 To assess the future of ecological communities, mechanistic models that build on biological processes observed at the level of individual organisms can be used to translate mechanisms and predictions to the ecosystem level. Allometric trophic networks (Martinez 2020, Brose et al 2006 or size spectra models (Law et al 2009, Blanchard et al 2017) use the allometric theory that describes the biological rates of species using body mass and temperature to quantify interspecific interaction strength in food webs and describe species biomass changes over time and environmental conditions (Binzer et al 2016, Martinez 2020. Allometric trophic network models were able to successfully predict the population dynamics of communities (Boit et al 2012, Curtsdotter et al 2019.…”

Body size dependent dispersal influences stability in heterogeneous metacommunities

“…In contrast to randomly-assembled communities, an emerging focus in modern biodiversity theory is on the non-random structural features of ecological systems that impart stability [4,8,9]. For communities organized around feeding relationships (i.e., food webs), two types of structure receiving extensive attention are allometric hierarchies, where larger species mostly eat smaller ones and populations experience other demographic rates dependent on body size [5,10,11]; and dispersal among spatially discrete habitats [12,13,14,15].…”

“…Body size-based food web topologies and allometric scaling of population demographic rates have both shown to be stabilizing for models of trophic interactions [5,6,10,16,17]. Simple mass-based hierarchical feeding rules -where species high in the feeding hierarchy are interpreted as largebodied predators -can successfully reproduce realistic food web topologies [4,5,11,18,19,20,21] that are more likely to be dynamically stable than random network con gurations [16,17]. Likewise, allometric scaling of species' demographic rates such as handling times, conversion e ciencies, and biomass turnover, are predicted to stabilize food webs [5,10,22,23,24,25].…”