Integrating vital rates explains optimal worker size for resource return by bumble bee workers

1. Size-number trade-offs in reproduction are commonly observed in nature. Bumble bee (Bombus spp.) colonies produce workers that vary considerably in size. This variation suggests that colonies face potential size-number trade-offs when producing workers.
2. Here, we estimated size-based vital rates of Bombus vosnesenskii workers using colonies reared from wild caught queens. We conducted a mark-recapture study to estimate worker survival as a function of body size. We also collected data on pollen and nectar loads as well as foraging trips using a radio-frequency identification system to estimate daily resource return as a function of body size. We integrated survival and daily resource return to estimate lifetime resource collection and offset these estimates by the size-based worker production costs.
3. We found size-based trade-offs among workers of different sizes. Smaller workers had higher survival, but larger workers returned with more resources per day. The largest workers ...

1. 繁殖过程中的体型-数量权衡现象在自然界中普遍存在。熊蜂（Bombus spp.）蜂群所产生的工蜂体型差异显著，这一现象表明蜂群在培育工蜂时，可能面临体型与数量之间的权衡取舍。
2. 本研究以野外捕获的蜂王培育的沃氏熊蜂（Bombus vosnesenskii）蜂群为实验材料，估算了不同体型工蜂的生命率参数。我们通过标记-重捕法，以体型为自变量估算工蜂的存活率；同时借助射频识别（radio-frequency identification, RFID）系统，采集工蜂的花粉与花蜜携载量、觅食行程等数据，以体型为自变量估算其每日资源带回量。随后整合存活率与每日资源带回量，估算工蜂一生的总资源采集量，并基于工蜂体型对应的培育成本对该估算值进行校正。
3. 研究发现不同体型的工蜂间存在基于体型的权衡关系：体型较小的工蜂存活率更高，而体型较大的工蜂每日带回的资源量更多。体型最大的工蜂……