Hunger state and not personality determines task participation in a spider society. (August 2022) - Parthasarathy, Bharat
Abstract : Task specialization is a hallmark of social success as it can minimize among-individual conflict in task participation, and thereby optimize colony productivity. Task specialization is therefore predicted to manifest as a consequence of social evolution. While age or caste in some species explains task participation, a recent hypothesis states that personality type determines differential task participation and thereby facilitates specialization. The social spider Stegodyphus sarasinorum exhibits no castes or conspicuous dominance hierarchies or age polyethism yet shows consistent among-individual differences in prey capture. We tested whether one personality trait (boldness) determines task specialization by exploring the determinants causing consistent participation in prey attack. By integrating a personality type and individual hunger, we tested two mutually exclusive hypotheses. (1) Among-individual differences in personality determine consistent differences in participation in prey capture, leading to specialization. (2) Individuals are flexible, and individual hunger state determines the propensity to capture prey. We found that hunger state was the only significant determinant of attacking prey . By reversing individual hunger state, we were able to dramatically increase or decrease individual attack propensities. Spiders exhibited consistent among-individual differences in boldness, yet this personality type did not predict foraging participation. Therefore, we found no evidence for behavioural specialization in prey capture. Our study emphasizes the importance of internal state as a mechanism underlying variable task participation, suggesting caution in attributing behavioural specialization to personality without appropriate integration of state-dependent effects. Highlights: Personality types are proposed to govern task specialization. We found no evidence for personality-mediated task specialization in Stegodyphus sarasinorum . We show that internal state determines task participation. Personality studies must integrate confounding internal states of the animal. Task specialization is not an inevitable manifestation of social evolution.