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 syndrome）的研究关注度与日俱增，但针对为何不同的行为性状会演化出相关性，目前仍缺乏系统性的解释。本研究旨在探究：这类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）差异得到解释。生活史理论（life history theory）指出，个体将能量分配至体细胞维持或繁殖的模式，会调控生理、形态及能量利用等多个维度的性状；同时该理论还预测，个体参与风险行为的意愿与其繁殖策略密切相关。我们以盘腹蚁属（Temnothorax）蚂蚁为研究对象，已有研究表明该类蚂蚁在蚁群层面展现出“个性”特征，且存在可反映群体风险耐受度的行为综合征。我们对比了蚁群在生长速率（即新生工蚁的产出量）与繁殖投入（即雄性繁殖蚁与处女王的产出量）方面的相对投资情况。将不育工蚁的产出与有翅繁殖蚁（reproductive alate）的产出进行对比，可以直接量化蚁群的能量分配模式，这与单体生物（unitary organism）中生长与繁殖的能量投资逻辑相仿。研究结果与上述假说一致：蚁群的行为类型与其生活史策略显著相关——耐受风险的蚁群生长速率更快，且对繁殖的投入更高；而规避风险的蚁群生长速率更低，但相对更多地投资于工蚁培育。本研究证实，行为综合征可由生活史策略的差异演化而来，这为联结动物个性与行为综合征、生活史理论两大研究领域提供了实证支撑，并验证了整合研究方法的应用价值。