PARENT SESSION
Oral Session #91: Mutualisms -- Facultative, conditional, and complex.
Presiding: W. Wilson
Thursday, August 8. 1:00 PM to 3:45 PM. Cochise Meeting Room, TCC.

Conditionality in ant protection mutualisms: the role of resource availability.

Weeks, Jennifer^*,1, ¹ University Of Arizona, Tucson, AZ

ABSTRACT- Conditionality, the variation in the occurrence, strength, or outcome of an interspecific interaction generated by the ecological context in which it occurs, may exert strong influences on the ecology and evolution of species interactions. Lycaenid-ant interactions are a convenient system in which to study the causes and consequences of conditionality in mutualistic interactions. The availability and balance of nutritional resources plays an important role in the foraging behavior of ants and is therefore likely to have a strong impact on the associations between ants and exudate-producing plants and insects. I investigated the effects of ant diet on the facultative, mutualistic association between the ant, Crematogaster opuntiae and the lycaenid butterfly, Hemiargus isola. I found that a significantly larger proportion of foragers from ant colonies fed a high protein/low-carbohydrate diet recruited to lycaenids than from colonies fed a low-protein/high carbohydrate or balanced diet. Within all diet treatments, ants exhibited variation in the magnitude of response to individual lycaenid larvae. These results demonstrate that factors external to the interaction can alter the strength of the association. The availability of alternative nutritional resources in the form of other exudate-producing plants and insects as well as the availability of insect prey is likely to have a strong effect on the intensity and outcome of ant-protection mutualisms.

KEY WORDS: mutualism, conditionality, lycaenid , ants