Large body size variation is linked to low communication success in tandem running ants

Abstract

Large body size variation is linked to low communication 1 success in tandem running ants 2 3 4 Abstract 22Diversity in animal groups is often assumed to increase group performance. In insect colonies, 23 genetic, behavioral and morphological variation among workers can improve colony 24 functioning and resilience. However, it has been hypothesized that during communication 25 processes, differences between workers, e.g. in body size, could also have negative effects. 26Tandem running is a common recruitment strategy in ants and allows a leader to guide a 27 nestmate follower to resources. A substantial proportion of tandem runs fail because leader and 28 follower loose contact. Using the ant Temnothorax nylanderi as a model system, we tested the 29 hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, 30 we found that the success rate of tandem pairs drops considerably as size variation increases: 31 only ~7% of tandem runs were successful when the leader-follower size difference exceeded 32 10%, whereas 80% of tandem runs were successful when ants differed less than 5% in body 33 length. One possible explanation is that ant size is linked to the preferred walking speed. Ants 34 did not choose partners of similar size, but extranidal workers were larger than intranidal 35 workers, which could reduce recruitment mistakes because it reduced the chance that very large 36 and very small ants perform tandem runs together. Our results suggest that phenotypic 37 differences between interacting workers can have negative effects on the efficiency of 38 communication processes. Whether phenotypic variation has positive or negative effects is 39 likely to depend on the task and the phenotypic trait that shows variation. 40 41 42 Social groups consist of individuals that differ from each other in a number of ways. For 43 instance, people working in a company may differ in experience, training, gender, ethnicity or 44 skills and this diversity can affect group performance and success. Scientists interested in 45 organizational theory have found that group diversity often has positive effects on group 46 performance, most likely because diverse groups possess a broader range of knowledge, 47