Ant personalities and behavioral plasticity along a climatic gradient

Abstract

Variable environments can select for behavioral plasticity. Yet, along environmental gradients, personalities (consistent differences in behavior) and behavioral syndromes (associations between behavioral traits) can arise both across and within populations, which point to limits in behavioral plasticity. To date, little is known on how behavioral plasticity and animal personalities are associated along geographical gradients. Hereto, we subjected colonies of the ant Temnothorax longispinosus from populations along a natural climatic gradient to temperature manipulations and behavioral experiments. We asked whether personalities and behavioral syndromes stem from local adaptations or are plastic responses and whether the extent of behavioral plasticity differs between populations from warmer versus colder habitats. Our results reveal that colonies responded to warmer temperatures with increased explorative and brood care behavior. Interestingly, these behavioral traits shifted in the same direction as a syndrome previously found along this climatic gradient, where colonies from warmer environments displayed more exploration and brood care. Additionally, colonies that exhibited lower aggression but more exploration prior to temperature manipulations showed the highest behavioral plasticity. Moreover, only in one behavioral trait, exploration, colonies from colder sites exhibited higher plasticity than those from warmer sites. This suggests that ant behaviors are influenced mostly by prevailing conditions with a limited influence of past experience on behavioral plasticity. Our study proposes that associations between behavioral traits can be modified by climatic conditions, thus providing insights into the complex ways animals respond to current and past environments. Behavioral plasticity and animal personalities could be linked to climate. Yet few studies have investigated behavioral associations along geographical gradients. Hence, we still lack an understanding of how current and past environmental conditions affect such behavioral associations along gradients. Here, we asked whether the extent of behavioral plasticity differs between populations from warmer versus colder sites along a climatic gradient and whether animal personalities stem from local adaptations or plastic responses. We demonstrate in a social insect that associations between behavioral traits can be modified by temperature. Specifically, in response to temperature changes, behavioral traits shifted in a direction consistent with variation in a syndrome across a climatic gradient. This study provides unique empirical support linking animal personalities and phenotypic plasticity across populations along climatic gradients, thus offering new insights into the complex ways animals respond to current conditions and past experience.