Who goes there? Social surveillance as a response to intergroup conflict in a primitive termite

Abstract

Intergroup conflict has been suggested as a major force shaping the evolution of social behaviour in animal groups. A long-standing hypothesis is that groups at risk of attack by rivals should become more socially cohesive, to increase resilience or protect against future attack. However, it is usually unclear how cohesive behaviours (such as grooming or social contacts) function in intergroup conflict. We performed an experiment in which we exposed young colonies of the dampwood termite, Zootermopsis angusticollis , to a rival colony while preventing physical combat with a permeable barrier. We measured social contacts, allogrooming and trophallaxis before, during and after exposure. Termites showed elevated rates of social contacts during exposure to a rival compared to the pre-exposure phase, but rates returned to pre-exposure levels after colonies were separated for 9 days. There was evidence of a delayed effect of conflict on worker trophallaxis. We suggest that social contacts during intergroup conflict function as a form of social surveillance, to check individual identity and assess colony resource holding potential. Intergroup conflict may increase social cohesion in both the short and the long term, improving the effectiveness of groups in competition.

Marking through molts: An evaluation of visible implant elastomer to permanently mark individuals in a lower termite species

“…A reduction in this type of behavior could indicate an energetic cost to the VIE implant. Increased antennation in treatment individuals could indicate that they were more stimulated by their social environment than controls as antennation has been associated with identity‐checking and other social communication in termites (Thompson et al., 2020 ). However, we did not find a difference in the level of manipulation of the (abiotic) environment between treatment and control groups, suggesting that there was no general increase in response to external stimuli.…”

Extended and cumulative effects of experimentally induced intergroup conflict in a cooperatively breeding mammal

“…A recent laboratory-based study on harvester ants ( Messor barbarus ), for example, found evidence for a ‘priming' effect: if there had been an earlier presentation of an intruder (20 min before), there was a greater increase in ant activity and contact between groupmates in response to a second intrusion [ 18 ]. Multiple outgroup interactions could also have a cumulative effect; such a build-up of threat could result in behavioural changes not only in the immediate aftermath of each interaction, but also more generally [ 22 ]. From a proximate perspective, repeated exposure to a stressor could lead to dysregulation of the HPA axis, and consequent changes to baseline behaviour [ 32 , 33 ].…”

The dynamics of social cohesion in response to simulated intergroup conflict in banded mongooses

“…While these theoretical models are concerned with the coevolution of altruism and intergroup hostility over many generations, empirical studies of intergroup conflict in both human and animal societies have focused on the short‐term behavioral consequences of outgroup threats (see Table 1 ). One widely held idea is that groups exposed to intergroup conflict should pull together and become more cohesive or affiliative, sometimes called the “conflict‐cohesion” hypothesis (Thompson et al, 2020 ). In an evolutionary context, this predicted response could be adaptive if increased cohesion or affiliation helps individuals and groups to reduce the costs or realize the benefits of intergroup competition and provide the building block to altruism within groups.…”