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）的研究热度持续攀升，但针对不同行为性状为何会演化出相关性的解释仍较为匮乏。本研究旨在探究，外观上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。生活史理论预测，单个蚁群将能量分配至体细胞维持或繁殖的方式，会驱动生理、形态与能量利用等多个不同性状的演化；同时该理论还预测，个体参与风险性行为的意愿取决于其繁殖策略。我们以扁胸切叶蚁属（Temnothorax）蚂蚁为研究对象，该类群已被证实展现出‘个性’以及可反映蚁群层面风险耐受度的行为综合征。我们对比衡量了蚁群在生长速率（繁育新工蚁）与繁殖投入（繁育雄蚁与处女蚁后）间的相对投资。将不育工蚁繁育与生殖型有翅成虫繁育进行对比，可直接量化蚁群的能量投入模式，这与单体生物（unitary organism）在生长与繁殖间的投资权衡具有类比性。与该理论预期相符，我们发现蚁群的行为类型与其生活史策略显著相关：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，但对工蚁繁育的相对投入更高。本研究结果证实，行为综合征可作为生活史策略差异的产物，为这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。