RETRACTED: The personality types of key catalytic individuals shape colonies' collective behaviour and success

Abstract

Keywords:Araneae behavioural syndrome collective behaviour keystone individual personality spider Stegodyphus dumicola temperament Behavioural ecologists often note that one or a few group members appear to shape the collective behaviour of social groups differentially. Our understanding of these keystone individuals is largely taken from meticulous field observations and semi-scientific anecdotes. In this study we experimentally test whether the behavioural tendencies of putative keystone individuals shift the collective behaviour of colonies using the social spider Stegodyphus dumicola. Prior studies on Stegodyphus demonstrated that the single best predictor of colonies' collective behaviour is the behaviour of colonies' boldest individual. Here, we probe the causal relationship between the traits of extremely bold individuals and colonies' collective behaviour by experimentally creating colonies of identical size and personality composition in the laboratory and then adding a single individual of varying boldness (the putative keystone individual). Experimentally adding just one extremely bold individual increased the foraging aggressiveness of entire colonies and altered the total mass gained by fellow group members, relative to the addition of a less bold individual. Additionally, our data suggest that bold individuals are capable of such influence because they catalyse variation in the behavioural tendencies of fellow group members.The Association for the Study of Animal Behaviour. Published by Elsevier Ltd.

The Achilles' heel hypothesis: misinformed keystone individuals impair collective learning and reduce group success

“…For a few days after colony establishment, keystone individuals initiate and complete a disproportionately large number of prey capture and web repair events [31,35]. This means that keystone individuals are potentially the first individuals to obtain information about their new environment, and these individuals may be more adept at spreading such information because of their enhanced social influence.…”

“…These bold individuals appear to exert their disproportionately large influence over group behaviour (i.e. act as keystone individuals) by catalysing aggressive foraging behaviour in their otherwise shy colony mates [31,34]. The longer that keystone individuals remain in a group, the more dramatic their effects become and the longer their effects linger following their departure or death [34].…”

“…Links between personality and probability of becoming keystone individuals are fairly common [14,33]. In S. dumicola, the link between boldness and keystone-ness is particularly strong (R 2 ¼ 0.36-0.67) [30,31]: simply adding one very bold individual to a colony increases the number of attackers that respond to live prey by 300-600% and increases the mass gained by societies as a whole by 300%, and these effects linger for weeks after a keystone individual's removal [34]. No such effects are observed when the presence of shy individuals is manipulated.…”

“…In S. dumicola, particularly bold individuals, which previous work indicates function as keystone individuals [30,31], are often the first individuals to interact with both prey and predators following dispersal. For a few days after colony establishment, keystone individuals initiate and complete a disproportionately large number of prey capture and web repair events [31,35].…”

“…In the social spider Stegodyphus dumicola (Araneae, Eresidae), a group's boldest individual has a disproportionately large influence over group hunting behaviour and success [30,31]. Boldness is defined as an individual's tendency to place themselves in a threatening situation [32], which in S. dumicola is expressed as a short latency to resume normal activity after being presented with an aversive stimulus.…”