DIFFERENTIAL LEARNING AND MEMORY BY COOCCURRING ANT SPECIES

Foragers of the ants Messor pergandei and Pogonomyrmex rugosus experience differing levels of variability in the distribution of seeds they harvest due to species-specific differences in foraging behavior. Messor pergandei foragers experience more variable seed distributions and densities, learn to recognize a novel seed faster but forget this information faster than P. rugosus, which experiences more constant seed distributions even in the same habitat. Rate of learning to recognize a novel seed species was negatively associated with measures of seed species diversity for both ants. Messor pergandei foragers respond to variation in seed density by varying number of seeds handled per seed harvested, while P. rugosus foragers do not. Memory of a novel seed exceeds forager longevity, due perhaps to use of seed caches as a type of information center.