COS 140-5 - On the dynamic nature of omnivory in a changing world

Wednesday, August 17, 2022

9:00 AM – 9:15 AM EDT

Location: 512E

Presenting Author(s)

MG

Marie K. Gutgesell

Ph.D. Candidate
University of Guelph, Ontario, Canada

Coauthor(s)

KM

KEVIN S. MCCANN

Professor
University of Guelph
GUELPH, Ontario, Canada
GG

Gabriel Gellner

Post doctoral researcher
University of Guelph
Ottawa, Ontario, Canada
KC

Kevin Cazelles

Postdoctoral Researcher
University of Guelph, Canada
CG

Christopher J. Greyson-Gaito

Ph.D. Student
University of Guelph, Canada
CB

Carling Bieg, n/a

Ph.D. Candidate
University of Guelph
Guelph, Ontario, Canada
MG

Matt Guzzo

Post Doc
University of Guelph, Canada
CW

Connor Warne

Ph.D. Candidate
University of Guelph, Canada
CW

Charlotte A. Ward

Ph.D. Student
University of Guelph, Ontario, Canada
RO

Reilly F. O'Connor

MSc Student
University of Guelph, Ontario, Canada
AS

Alexa M. Scott

M.Sc Student
University of Guelph, Canada
BG

Brandon Graham

M.Sc Student
University of Guelph, Canada
EC

Emily Champagne

M.Sc. Student
University of Guelph, Canada
BM

Bailey McMeans

Assistant Professor
University of Toronto Mississauga, Canada

Background/Question/Methods

Nature’s variability plays a major role in maintenance of biodiversity. As global change is altering variability, understanding how key food web structures maintain stability in the face of variation becomes critical. Surprisingly, little research has sought to mechanistically understand how key food web structures are expected to operate in a noisy world, and what this means for stability. Omnivory, for example, has been historically well studied but largely from a static perspective. Recent empirical evidence suggests the strength of omnivory varies in response to changing conditions in ways that may be fundamental to stability. We extend existing omnivory theory to develop a dynamic omnivory framework aimed at understanding how omnivory responds to changing conditions and synthesize current empirical examples of dynamic omnivory within this theoretical framework.

Results/Conclusions

When looked at dynamically (i.e., the strength of omnivory through time) there are two general categories of mechanisms promoting dynamic omnivorous responses by organisms, both of which are potent stabilizers in the face of environmental variation. First, there are bottom-up driven conditions in which environmental conditions alter the production of plants or animals in a manner that pushes predators to optimally forage more on lower-level prey (bottom-heavy omnivory). Second, there are cases where environmental conditions and organismal traits (e.g., high interaction strengths) can generate strong cascading predator influences that implicitly drive biotic conditions that promote dynamic omnivory responses (top-heavy omnivory). Through our synthesis of empirical examples within this framework we demonstrate the ubiquity of the theoretical mechanisms proposed across ecosystem types, spatial scales and taxa. We propose that collectively this dynamic understanding of omnivory importantly allows us to begin to consider how global change will alter carbon transfer, stability, and production in whole food webs.