Data from: Life-history strategy and behavioral type: risk-tolerance reflects growth rate and energy allocation in ant colonies

Despite the recent interest in animal personality and behavioral syndromes, there is a paucity of explanations for why distinct behavioral traits should evolve to correlate. We investigate whether such correlations across apparently distinct behavioral traits may be explained by variation in life history strategy among individual ant colonies. Life history theory predicts that the way in which individuals allocate energy towards somatic maintenance or reproduction drives several distinct traits in physiology, morphology, and energy use; it also predicts that an individual's willingness to engage in risky behaviors should depend on reproductive strategy. We use Temnothorax ants, which have been shown to exhibit ‘personalities’ and a syndrome that may reflect risk tolerance at the colony level. We measure colonies' relative investment in growth rate (new workers produced) compared to reproductive effort (males and queens produced). Comparing sterile worker production to reproductive alate production provides a direct measure of how colonies are investing their energy, analogous to investment in growth versus reproduction in a unitary organism. Consistently with this idea, we found that behavioral type of ant colonies was associated with their life history strategy: risk-tolerant colonies grew faster and invested more in reproduction, whereas risk-averse colonies had lower growth rate but invested relatively more in workers. This provides evidence that behavioral syndromes can be a consequence of life-history strategy variation, linking the two fields and supporting the use of an integrative approach.

尽管近年来学界对动物个性（animal personality）与行为综合征（behavioral syndromes）的研究热度渐增，但针对为何不同的行为性状会演化出相关性，目前仍鲜有合理解释。本研究旨在探究，看似迥异的行为性状间的相关性，是否可通过单个蚁群的生活史策略（life history strategy）差异加以阐释。生活史理论（Life history theory）预测，个体将能量分配至体细胞维持或繁殖的方式，会调控生理学、形态学与能量利用层面的多项性状；同时该理论还指出，个体参与风险行为的意愿，与其繁殖策略密切相关。本研究以盘腹蚁属（Temnothorax）蚂蚁为研究对象，已有研究证实该类群蚁群展现出“个性”特征，且存在可反映蚁群层面风险耐受度的行为综合征。我们量化了蚁群在生长速率（即新增工蚁的产出）与繁殖投入（即产生雄性繁殖蚁与处女蚁后）两方面的相对投资。相较于不育工蚁的产出，具翅繁殖蚁的产出可直接反映蚁群的能量分配模式，这与单体生物（unitary organism）的生长与繁殖投资的类比逻辑一致。本研究结果与该假说相符：蚁群的行为类型与其生活史策略显著关联——风险耐受型蚁群生长速率更快，且对繁殖的投入更多；而风险规避型蚁群生长速率较低，但对工蚁的相对投入更高。该研究结果证实，行为综合征可由生活史策略的差异所导致，这为两个研究领域搭建了关联桥梁，并支持采用整合性研究方法的可行性。