PARENT SESSION
Oral Session # 83: Ecological Theory II: Modeling; Competition.
Presiding: C Brassil
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 201.
Consequences of trait variation on trophic interactions and abundances in a food chain.
Ovadia, Ofer1, zu Dohna, Heinrich1, Schmitz, Oswald1, 1 School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
ABSTRACT- Classical theory aiming to predict community structure and function assumes that smaller-scale details such as individual traits can be abstracted safely and that community dynamics can be simply characterized in terms of net changes in population densities. Here we use a computational model that consists of a three-level food chain to explore the effect of initial body size variation among herbivores on community dynamics resulting from non-linear relationship between population demography and body size. We illustrate that initial herbivore body size variation has a negative effect on their survival and consequently a positive effect on the final plant biomass. We then use trait distribution in combination with body size-survival and -fitness curves estimated through simulations to generate predictions for comparison with observed food chain effects. We show that, at the population-level, generating accurate predictions requires estimating fitness curves by incorporating relevant frequency-dependent effects. However, at the community-level, this frequency-dependence as well as changes in consumer population size can be abstracted safely and community dynamics can be simply predicted from initial trait distribution in combination with the survival curve. Our findings suggest a need to revisit classical theory, opening a new research avenue for community ecology. Doing so will require mechanistically studying population demography and experimentally testing the effect of trait variation on community dynamics.
Key words: nonlinearity, trait variation, trophic interactions, food chain