Behaviourally specialized foragers are less efficient and live shorter lives than generalists in wasp colonies
Behaviourally specialized foragers are less efficient and live shorter lives than generalists in wasp colonies
复制标题
在黄蜂群中，行为专业化的觅食者比通才者效率更低，寿命更短
作者：
D. Santoro;S. Hartley;P. Lester
生态学中一个被广泛接受的假设是，专家比通才更有效率。然而，这一基本假设的经验证据出奇地少，而且往往是相互矛盾的。从理论上讲，替代生活史策略的进化是由活动水平和生存之间的权衡所支撑的。我们通过比较一种群居昆虫——普通黄蜂（Vespula vulgaris）中近亲个体的表现和寿命，研究了觅食环境中专业化的后果。利用射频识别技术，对自然觅食条件下饲养的3个蜂群的胡蜂个体的一生觅食活动进行了监测。返回的觅食者经过巢穴入口时被录像，以便评估它们的觅食负荷。蚁群内和蚁群间的觅食活动和存活率存在显著差异。在群体水平上，觅食专业化程度较弱。然而，每个巢内的工蚁都表现出了显著的觅食专业化水平（定义为个体和群体任务分配之间的重叠程度）和效率（定义为成功旅行的次数和旅行的持续时间）。我们发现，在同一群体中，专业觅食者的效率低于通才觅食者。行为专家在每个觅食日完成的成功旅行较少，而且他们的旅行通常相对较长。专门的觅食动物的预期寿命也缩短了。在该领域花费相对较多时间的个体死亡风险较高，但我们发现专业化水平与相关领域暴露之间没有联系。我们前所未有的详细的广泛数据集提供了强有力的经验证据，表明行为专业化与更好的终身表现无关，相反，普通黄蜂的情况正好相反。我们还表明，根据经典的生活史理论预测，基因相似的个体的生存可能与终生的行为差异有关。
A widely held assumption in ecology is that specialists are more efficient than generalists. However, empirical evidence for this fundamental assumption is surprisingly scarce and often contradictory. Theoretically, the evolution of alternative life history strategies is underpinned by a trade-off between activity levels and survival. We investigated the consequences of specialization in a foraging context, by comparing the performance and longevity of closely related individuals in a social insect, the common wasp (Vespula vulgaris). Using radio-frequency identification technology, we monitored the lifetime foraging activity of individual wasps from three colonies kept under natural foraging conditions. Returning foragers were video-recorded as they passed the nest entrance so that their foraging load could be assessed. There were substantial differences in foraging activity and survival within and between colonies. At the colony level, foraging specialization was weak. Yet, workers within each nest demonstrated a remarkable range of foraging specialization levels (defined as the degree of overlap between individual and colony-level task allocation) and efficiencies (defined by the number of successful trips and trip duration). We found that specialist foragers were less efficient than generalist siblings within the same colony. Behavioural specialists accomplished fewer successful trips per foraging day, and their trips were typically relatively longer. Specialized foragers also showed reduced life expectancy. The mortality risk was higher for individuals spending relatively more time in the field, yet we found no link between the level of specialization and relative field exposure. Our extensive dataset of unprecedented detail provides strong empirical evidence that behavioural specialization is not associated with a better lifetime performance, on the contrary, the opposite appears true for the common wasp. We also show that the survival of genetically similar individuals can be linked to life-long differences in behaviour according to classical life-history theory predictions.