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Individual variation in the behavior of harvester ant (Messor andrei) colonies

Noa Pinter-Wohlman (Stanford University)


Ants live in complex societies. The behavior of an ant colony, such as foraging for food, emerges from the actions of the workers comprising it. Colony behavior arises from local rules that each individual ant follows with no single individual ordering others and no global control. Both workers and colonies vary in their behavior. Because colonies are the reproductive unit, i.e., colonies produce more colonies, but workers do not produce more workers, variation at the colony level is evolutionarily important. Variation among colonies in how they respond to their environment can lead to variation in how many offspring they produce.

Messor andrei, the black seed harvester ant, is abundant in serpentine grasslands at Jasper Ridge. Their nest mounds are conspicuous because they are covered with seed chaff that the ants discard. These ants are active from early spring to late fall and can be seen foraging, mostly for seeds, in the mornings and evenings. Interestingly, M. andrei colonies move among nest sites, and can relocate up to 10 times a year. I examine the behavior of M. andrei colonies in foraging and disturbance situations and ask whether these behaviors are consistent when a colony inhabits a particular nest site. I also examine how colonies adjust their behavior to changing weather conditions and ask if colonies vary in their response to environmental changes. 

Head close-up showing mandibles.

Project Location (Sectors 24, 33)

Visible from Trail/Road

F - Grassland Fire Road