Leaders benefit followers in the collective movement of a social sawfly

Abstract

The challenges of maintaining cohesion while making collective decisions in social or aggregating insects can result in the emergence of a leader or leaders. Larval aggregations of the steel-blue sawfly Perga affinis forage nocturnally, and some larvae lead the aggregation on foraging trips more often than expected by chance. We investigated the relationship between these leader and follower roles by comparing the weight and growth of individual larvae with different roles. Our observations reveal no significant difference between the growth of leaders and followers, suggesting that the role of leadership may not provide direct foraging benefits. However, by experimentally manipulating the social structure of larval aggregations, we found that individuals within aggregations that comprise a mixture of leaders and followers enjoy higher growth rates than those in aggregations comprising a single behavioural type. These data demonstrate, for the first time, individual benefits to maintaining a balance of leader and follower roles within larval aggregations, and highlight the importance of considering the perspectives of both leaders and followers when investigating the evolutionary significance of this behavioural variation within animal groups.

What's your move? Movement as a link between personality and spatial dynamics in animal populations

“…This may reduce overall dispersal success in ecosystems with this resource distribution (as in some human-altered habitats), resulting in lower connectivity among populations. Indeed, recent studies emphasise the role individuals play in their environment or in their social groups in the context of movements, including migration (Chapman et al 2011), invasion (Chapple et al 2012), dispersal (Cote & Clobert 2007;Cote et al 2010;Clobert et al 2012;Wey et al 2015) or collective searching (Hodgkin et al 2014;Farine et al 2015). In these examples correlations across scales need to be considered.…”

Individual and Group Personalities Characterise Consensus Decision‐Making in an Ant

“…However, other studies indicate that groups comprising a mix of behavioural types may have advantages (Johnstone & Manica ; Hodgkin et al. ) and that in some environments, smaller groups can make better decisions than larger ones (Kao & Couzin ). Furthermore, the influence of group composition may vary between species (Modlmeier et al.…”

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