Individual variation in parental tradeoffs between the number and size of offspring at the pre- and post-natal stages
Individual variation in parental tradeoffs between the number and size of offspring at the pre- and post-natal stages
复制标题
产前和产后阶段父母在后代数量和大小之间权衡的个体差异
作者：
Li, Jian-Chuan;Gao, Li-Fang;Du, Bo
生活史理论预测，父母参考他们拥有的资源来决定他们的繁殖策略。在多育雏物种中，据推测，单育雏父母产生更大的离合器和提高后代的育雏生存策略，而多育雏父母只有在良好的繁殖条件下才这样做。在恶劣的条件下，他们生产更小的离合器和提高后代与育雏减少战略。我们测试了这一假设在褐颊笑画眉Trochalopteron henrici，这可以在青藏高原上繁殖一年两次，通过调查的生活史特征和供应行为的单，双育雏父母。单窝父母奠定了更大的离合器较小的鸡蛋，并产生更多和更大的雏鸟比双窝父母在他们的第一窝。双育雏父母产生较小的离合器较大的鸡蛋，但羽翼较大的雏鸟在他们的第一窝比在他们的第二窝。由于单窝父母一年只需要养育一窝，那么生产和养育尽可能多的后代（即在大窝中的育雏生存策略）可以最大限度地提高他们的繁殖成功率。对于双窝父母，在第一窝中生产和养育较少的后代（即在小窝中的窝生存策略）可以确保他们在短繁殖周期内成功筑巢。此外，生产更多的后代，但提高较大的雏鸟在第二次育雏（即育雏减少策略，在一个大的育雏）可以选择更高质量的后代在育雏。我们的研究结果表明，不同的权衡之间的单，双育雏父母在产卵和育雏可能是一种适应的季节变化的环境条件。
Life-history theory predicts that parents refer to the resources they hold to determine their breeding strategy. In multi-brooded species, it is hypothesized that single-brooded parents produce larger clutches and raise offspring with a brood survival strategy, whereas multi-brooded parents only do this under good breeding conditions. Under poor conditions, they produce smaller clutches and raise offspring with a brood reduction strategy. We tested this hypothesis in the Brown-cheeked Laughing ThrushTrochalopteron henrici, which can breed twice a year on the Tibetan Plateau, by investigating the life-history traits and provisioning behaviours of single- and double-brooded parents. Single-brooded parents laid larger clutches of smaller eggs and produced more and larger fledglings than double-brooded parents in their first brood. Double-brooded parents produced smaller clutches of larger eggs but fledged larger nestlings in their first brood than in their second brood. As single-brooded parents only need to raise one brood a year, then producing and raising as many offspring as possible (i.e. the brood survival strategy in a large brood) can maximize their reproductive success. For double-brooded parents, producing and raising fewer offspring in the first brood (i.e. the brood survival strategy in a small brood) can ensure their nesting success during a short breeding cycle. Additionally, producing more offspring but raising larger nestlings in the second brood (i.e. the brood reduction strategy in a large brood) can select for offspring of higher quality within the brood. Our findings indicate that different tradeoffs between single- and double-brooded parents in egg-laying and nestling-raising may be an adaptation to the seasonal variation in environmental conditions.