Applied Ecology, North Carolina State University, Raleigh, NC, United States of America.
PeerJ. 2022 Aug 2;10:e13859. doi: 10.7717/peerj.13859. eCollection 2022.
Honey bee males (drones) exhibit life histories that enable a high potential for pre- or post-copulatory sperm competition. With a numerical sex ratio of ∼11,000 drones for every queen, they patrol flyways and congregate aerially to mate on the wing. However, colonies and in fact drones themselves may benefit from a relative lack of competition, as queens are highly polyandrous, and colonies have an adaptive advantage when headed by queens that are multiply mated. Previous research has shown that larger drones are more likely to be found at drone congregation areas, more likely to mate successfully, and obtain a higher paternity share. However, the reproductive quality and size of drones varies widely within and among colonies, suggesting adaptive maintenance of drone quality variation at different levels of selection.
We collected drones from six colony sources over the course of five days. We paint marked and individually tagged drones after taking body measurements at emergence and then placed the drones in one of two foster colonies. Using an entrance cage, we collected drones daily as they attempted flight. We collected 2,420 drones live or dead, analyzed 1,891 for attempted flight, collected emergence data on 207 drones, and dissected 565 upon capture to assess reproductive maturity. We measured drone body mass, head width, and thorax width at emergence, and upon dissection we further measured thorax mass, seminal vesicle length, mucus gland length, sperm count, and sperm viability from the seminal vesicles.
We found that drones that were more massive at emergence were larger and more fecund upon capture, suggesting that they are of higher reproductive quality and therefore do not exhibit a trade-off between size and fecundity. However, smaller drones tended to attempt initial flight at a younger age, which suggests a size trade-off not with fecundity but rather developmental maturation. We conclude that smaller drones may take more mating flights, each individually with a lower chance of success but thereby increasing their overall fitness. In doing so, the temporal spread of mating attempts of a single generation of drones within a given colony increases colony-level chances of mating with nearby queens, suggesting an adaptive rationale for high variation among drone reproductive quality within colonies.
雄蜂（雄蜂）表现出的生活史使它们具有很高的潜在预交配或交配后精子竞争能力。在与蜂王的数量比约为 11000:1 的情况下，它们在飞行通道上巡逻并在空中聚集交配。然而，由于蜂王高度多配偶制，而且当由多次交配的蜂王领导时，殖民地实际上可能从相对缺乏竞争中受益，殖民地和雄蜂本身可能受益于相对缺乏竞争。以前的研究表明，较大的雄蜂更有可能在雄蜂聚集区被发现，更有可能成功交配，并获得更高的父权份额。然而，在不同的选择水平上，雄蜂的生殖质量和大小在殖民地内部和之间差异很大，这表明对雄蜂质量变异的适应性维持。
我们在五天的时间里从六个殖民地来源收集了雄蜂。我们在出现时对雄蜂进行身体测量，然后对其进行油漆标记和单独标记，然后将雄蜂放入两个寄养殖民地中的一个中。我们使用入口笼，每天在它们试图飞行时收集雄蜂。我们共收集了 2420 只活或死的雄蜂，对 1891 只进行了飞行尝试的雄蜂进行了分析，收集了 207 只雄蜂的出现数据，并在捕获时对 565 只雄蜂进行了解剖，以评估生殖成熟度。我们在出现时测量了雄蜂的体重、头宽和胸宽，在解剖时进一步测量了胸重、精囊长度、粘液腺长度、精子计数和精囊中的精子活力。
我们发现，在出现时体重较大的雄蜂在捕获时体型较大，繁殖力较强，这表明它们的生殖质量较高，因此不会在体型和繁殖力之间存在权衡。然而，较小的雄蜂往往在更年轻的时候开始首次飞行，这表明它们在体型上的权衡不是与繁殖力，而是与发育成熟度有关。我们得出的结论是，较小的雄蜂可能会进行更多的交配飞行，每次单独的成功机会较低，但这会增加它们的整体适应度。通过这种方式，给定殖民地中同一代雄蜂的交配尝试的时间传播增加了与附近蜂王交配的机会，这表明了在殖民地内部，雄蜂生殖质量的高度变异具有适应性的理由。
