Davidson 9707932 Studies will assess the relationship between "key innovations" in the digestive anatomy of ants and the carbohydrate (CHO) : protein (N) ratios in ant diets. Experimental manipulations of diet, together with other investigations, will determine the effects of CHO: N ratios on ant foraging "tempos" and paths (correlated with food discovery rates), territoriality, and offensive and defensive chemical weaponry. Stable isotope ratios, % dry weight nitrogen measures, and "giving-up concentrations" for CHO and N resources, will be investigated as potential indicators of ant dependency on plant resources and should be intercorrelated. The extent of evolved dependency of various ant taxa on exudates vs. prey will be further assessed in laboratory feeding trials. All comparisons among taxa will be made in legitimate phylogenetic contexts. The PIs will also examine the ways in which other organisms (plants, insects, etc.) may have evolved to manipulate ants via the CHON ratios of food rewards. Results should suggest ways in which ant taxa with different diets can be manipulated by CHO:N ratios in potential food sources. The PIs should also be useful in assessing the functional by which some pest ants have broken the evolutionary trade-off between characteristics leading to rapid resource discovery vs. those correlated with resource domination.