Exploring the Link Between Rescue Behavior and Experience in the Pavement Ant, Tetramorium sp. E
Rescue behavior, a specific form of altruism, has been recorded in diverse animal species. Pavement ants (Tetramorium sp. E) are capable of freeing nestmates trapped by antlions (Myrmeleontidae spp.), a common predator of ants and other insects. Although rescue behavior in T. sp E and other ant species is well-documented, the potential effects of previous rescue experience on patterns of future rescue behavior are unknown. Ants and many other insects show evidence of task specialization based on repeated prior exposure to certain stimuli, and in rats, individuals that have previously rescued a conspecific become more likely to perform rescue behavior later, given the opportunity. These findings suggest that ants may modify their expression of rescue behavior according to whether they have engaged in rescue behavior in the past. In this project, the effects of previous experience on subsequent patterns of rescue behavior were investigated by allowing ants to encounter a nestmate trapped by an antlion in two back-to-back experimental trials. The behavioral responses of ants that had engaged in rescue behavior during their previous confrontation with the antlion were compared to the responses of naïve ants that did not engage in rescue behavior during the initial encounter. Experienced and inexperienced ants presented with a second opportunity to rescue a nestmate did not differ in their likelihood to perform rescue behavior, did not perform more or fewer types of rescue behavior, did not demonstrate different latencies to engage in rescue behavior, did not spend different amounts of time performing rescue behavior, and did not exhibit shorter or longer periods of sustained rescue behavior. Ants that had performed rescue behavior in the initial trial displayed shorter bouts of sustained rescue behavior and performed less limb-pulling behavior in the second trial than in the initial trial. Taken together, these findings suggest that, rather than becoming more effective rescuers as a result of prior experience, T. sp. E individuals that have previously performed rescue behavior show increased reluctance to rescue in the future as a byproduct of predator avoidance behavior.
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