Universal laws in ecology

Author: Jody McKerral (Fisher)

McKerral (Fisher), Jody, 2021 Universal laws in ecology, Flinders University, College of Science and Engineering

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Multispecies communities are inherently complex, with a myriad of processes influencing their interacting parts. Yet, these communities often exhibit highly conserved emergent behaviour, which is suggestive of unifying organisational principles operating within ecological settings. Through investigating the distributions and scaling of organisms, their abundances, and metabolic diversity, this doctoral research explores potential mechanisms behind emergent behaviour at scales of both microbes and ecosystems. The association between organism physiology and ecosystem structure captured by size-abundance scaling laws is probed through an allometric setting of the Rosenzweig-Macarthur differential equations. Through extensions to the model motivated by empirical biological research and classical biophysics, it is shown that terrestrial and marine biospheres are fundamentally different, with turbulence restructuring the dynamics of oceanic ecosystems by imposing additional energetic costs on large organisms. The macro stability observed in size-abundance scaling laws is mirrored by a ubiquitous feature of functional stability within the microbial communities which sit at the base of the food web. To interrogate plausible assembly rules that may give rise to this behaviour, a network-based framework is used to link taxa and function, resolving a fundamental challenge in probing taxa-metabolism relationships in microbial ecology. Analysis across real-world microbial communities spanning major environmental and host microbiomes reveals a universal taxa-function structure, which would facilitate horizontal gene transfer and thus strengthen community stability and resilience.

Keywords: ecological modelling, scaling laws, population dynamics, microbial ecology, biological networks

Subject: Biological Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2021
School: College of Science and Engineering
Supervisor: Jim Mitchell