Data from: Task-dependent workload adjustment of female breeders in a cooperatively breeding fish

Parental investment affects the future survival and reproductive success of breeders. Therefore, breeders should optimize the amount of care they invest into the current offspring. In cooperative breeding systems, the amount of breeders’ parental care is influenced by the behavior of brood-care helpers. Such workload adjustment is expected to depend on the task that needs to be fulfilled. While investment rules of breeders in respect to single tasks are well investigated in many bird and mammal species, little is known about behavioral adjustment of breeders when dealing with multiple tasks. Here, we examined the workload adjustment in multiple tasks of female breeders in the cooperatively breeding fish Neolamprologus obscurus. By combining behavioral observations with helper removal experiments in a wild population, we found that female territory defense and offspring care significantly decreased with increasing helper number. Furthermore, the workload invested in these tasks significantly increased after the removal of a helper, suggesting load-lightening effects in territory defense and offspring care. On the other hand, female territory maintenance behavior (i.e. excavating sand from the breeding shelter) did not correlate with helper number. While sand excavation significantly increased after the helper removal experiment, the size of the excavated stone area decreased after the helper removal in the recent study, suggesting that sand excavation may have additive effects for the breeders. These results demonstrate and underline the importance of task dependent workload adjustment in cooperative breeders.亲本投入会影响繁殖者未来的存活与繁殖成功率，因此繁殖者应当优化其对当前子代的抚育投入量。在合作繁殖体系中，繁殖者的亲本抚育投入量会受到育幼帮手行为的影响。此类工作量调整理应取决于需要完成的任务类型。尽管诸多鸟类与哺乳类物种中，繁殖者针对单一任务的投入规则已得到充分研究，但学界对繁殖者处理多项任务时的行为调整机制仍知之甚少。本研究以合作繁殖性鱼类暗色栉丽鱼（Neolamprologus obscurus）的雌性繁殖者为对象，探究其在多项任务中的工作量调整策略。通过结合野生种群的行为观察与帮手移除实验，我们发现雌性的领地防御与子代抚育行为随帮手数量增加显著降低。此外，移除帮手后，繁殖者在这两项任务中的工作量显著上升，表明领地防御与子代抚育存在负载减轻效应（load-lightening effect）。另一方面，雌性的领地维持行为（即从繁殖庇护所中挖掘砂石）与帮手数量并无关联。尽管帮手移除实验后砂石挖掘行为显著增加，但本研究中帮手移除后挖掘出的砂石区域面积反而减小，这表明砂石挖掘可能对繁殖者存在附加效应。上述结果证实并强调了合作繁殖者中基于任务类型的工作量调整的重要性。