PARENT SESSION
Contributed Oral Session 145: Evolutionary Ecology: Population Dynamics
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal
Coexisting mutualist ant species competing for a renewable resource: Trait regulation to modify a dominance-discovery tradeoff.
Tanner, Colby*,1, Fitzgerald, Katherine2, 1 University of Utah, Salt Lake City, UT, United States2 University of Utah, Salt Lake City, UT, United States
ABSTRACT- Foraging animals use various strategies to compete for resources. These strategies can range from pure exploitation, in which the forager removes resources before competitors can gain access, to pure interference, in which the forager aggressively defends the resource against competitors. Such tradeoffs between dominance and discovery have been shown theoretically and empirically to facilitate coexistence. In most cases, however, this tradeoff only maintains coexistence when resources are ephemeral, sparse, and randomly distributed. Inspired by data from a system in which two ant species compete for access to a single aphid partner species, we use a game theoretical model to derive the necessary conditions for coexistence on a renewable, shared resource with a stable distribution. We also show how these foraging strategies are correlated with the regulation of particular character traits for each species. In this system, two mutualist ant species, Formica cf. integroides and F. xerophila, share a single partner aphid species, Chaitophorus populicola. F. xerophila uses an exploitative strategy, while F. cf. integroides uses an interference strategy. Our results suggest that these contrasting strategies can lead to coexistence when both competitors maintain possession of a critical amount of the dependable resource. To do this, however, both ants must regulate traits associated with their particular foraging strategies in ways that make each species forage suboptimally. Specifically, F. cf. integroides regulates its body size distribution while F. xerophila regulates its spatial-numerical distribution.
Key words: competition, coexistence, regulation