ant trajectoriesMessor andrei
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Many biological systems are complex aggregates of multiple agents working together towards collective, higher-order goals, and evolution acts on variation in these emergent collective properties. There is no central control dictating the activities of members in the assembly. Instead, agents use local signals that determine their behavior and are received through an intricate interaction network resulting in collective phenotypes. Thus, the composition of a group and the way its members interact affects the success of the group as a whole, just as the composition of any sports team dictates its success in the league.

I study the emergence of collective outcomes from group composition by combining field and lab studies with computer simulations, theoretical work, image analysis, and social network analysis.

I am also interested in the interplay between conservation biology and animal behavior. Examining the behavior of animals can provide important assessment tools for conservation actions and insights on preserving biodiversity. At the same time, wildlife management actions can provide unique opportunities for studying interesting questions in animal behavior. 

The effect of nest structure on the collective behavior of the true harvester ant, Veromessor andrei

Social behavior emerges from interaction networks which operate and form within a spatial context. To examine how spatial constraints influence the structure and function of these networks I study the behavior of the harvester ant Veromessor andrei. Colonies of these ants frequently relocate among subterranean nest sites [1] and change their collective behavior as they do so [2]. The architecture of the nest influences their collective behavior: the speed of recruitment to food increased with both chamber connectivity and a nest’s robustness to tunnel destruction behavior [3]. To examine whether nest architecture influences collective behavior through its impact on the ants’ interactions I combine lab and field experiments with social network analysis.

1. Pinter-Wollman N & Brown MJF. 2015. Variation in nest relocation of  harvester ants is affected by population density and food abundance. Behavioral Ecology. 26(6):1569–76.
2. Pinter-Wollman N, Gordon DM & Holmes S. 2012. Nest site and weather affect the personality of harvester ant colonies. Behavioral Ecology. 23(5):1022-9.
3. Pinter-Wollman N. 2015. Nest architecture shapes the collective behavior of harvester ants. Biology Letters. 11:20150695.

A plaster cast of a nest of  V. andrei:

The effect of group composition on the spread of the invasive Argentine ant, Linepithema humile

The spread of invasive species is determined not only by environmental factors but also by the behavior of the invading species. The invasive Argentine ant, L. humile, extends its range locally through the dispersal and establishment of propagules: groups of ants and queens. I examine whether the success of these propagules is determined by their composition. For example, rapidly finding a suitable nest site is affected by the proportion of exploratory individuals in a group [1]. Current work in my lab investigates the proximate mechanisms (development and gene expression) that underlie the behavioral variation among individual ants in exploration.

1. Hui A & Pinter-Wollman N. 2014. Individual variation in exploratory behaviour improves speed and accuracy of collective nest selection by Argentine ants. Animal Behaviour. 93:261-6.

 An argentine ant tending aphids:

Keystone individuals in the social spider Stegodyphus dumicola

In some societies, one or few individuals have a disproportionate impact on the collective behavior of the groups. Examples include leaders and tutors and a general term refers to these as ‘keystone individuals’. In the social spider Stegodyphus dumicola keystone individuals are bolder than all other group members and they expedite collective prey attack. Their influence over others is long lasting and persists even after they are no longer in the group [1]. I examine how interactions among individuals and behavioral persistence determine the impact of keystone individuals on the behavior of other group members.   

1. Pruitt JN & Pinter-Wollman N. 2015. The legacy effects of keystone individuals on collective behavior scale to how long they remain within a group. Proc. Roy. Soc. B. 282:20151766.