Reproductive behaviours in a risky world: are mothers trading-off offspring safety for future fitness?

行为是一种高度灵活的特征。它在不同个人之间以及在不同环境条件和不同生命阶段的个人内部都是不同的。在所有这些水平上，捕食风险是行为变化的主要决定因素。然而，个人不仅必须吃而不被吃，他们还必须在死亡风险和对生殖的投资之间取得平衡。一些被捕食的动物在捕食风险下减少了它们的父母行为和投资，如歌鸟所示。这种模式是否可以推广到其他有大量生殖投资的类群，还有待研究。此外，动物如何同时平衡自身生存、当前的生殖投资和未来的生殖投资，还知之甚少。小型啮齿动物是研究生殖和反捕食行为之间权衡的一个非常合适的研究系统。它们被高度掠夺，拥有灵活的交配系统(即可以单次交配或繁衍)，并有可能同时投资于雏鸟(当前投资)和怀孕(未来投资)。这在照顾现在的后代和暂时留下后代等待交配之间产生了冲突，以便能够投资于未来的后代。小型啮齿动物同时处于妊娠和哺乳的过程中，可以通过实验分离生命周期不同阶段的捕食风险对当前生殖投资(守巢)和未来生殖投资(交配行为)之间权衡的影响。本研究旨在通过实验研究不同生命阶段啮齿动物生殖行为应对捕食风险的灵活性和约束性：1)雏鸟的杀婴风险(当前生殖投资)对母亲择偶投资(未来生殖投资)的影响；2)母亲在寻找配偶方面的投资的捕食风险(未来的生殖投资)和3)母亲在其交配策略上的捕食风险(涉及投资的遗传多样性变化的单雄或多雄)。在所有实验中，将监测个体在时间分配、生理反应、空间使用和交配成功方面的变化，从而量化行为和健康的后果。实验将在不同的空间和时间尺度上进行：实验室中的行为观测和半自然围栏中的自动遥测观测。实验结果将对生殖行为的一般灵活性给出新的估计，并首次衡量在半自然环境中个体的生殖和死亡风险的生活史权衡。在第二个筹资阶段，可以研究在危险世界中生殖行为的适应对捕食者-猎物动态的潜在贡献。

Behaviour is a highly flexible trait. It varies among individuals as well as within individuals with environmental conditions and among life stages. Predation risk is a major determinant of behavioural variation at all of these levels. However, individuals do not only have to eat without been eaten, they also have to balance the risk of mortality with their investment into reproduction. Some prey animals reduce their parental behaviour and investment under predation risk, as shown for song birds. Whether this pattern can be generalized to other taxa with intense reproductive investment remains to be investigated. Moreover, little is known how animals can balance own survival, current reproductive investment, and future reproductive investment at the same time. Small rodents are a highly suitable study system for studying trade-offs between reproductive and anti-predatory behaviours. They are highly depredated, have flexible mating system (i.e. can mate singly or multiply), and can potentially simultaneously invest into nestling litters (current investment) and pregnancy (future investment). This produces a conflict between caring for the current offspring, and leaving the offspring temporally behind for mating in order to be able to invest into future offspring. With their concurrent and sequential pregnancy and lactation, small rodents are suitable study system to experimentally separate the effects of predation risk on different stages in the life cycle on the trade-off between current reproductive investment (nest guarding) and future reproductive investment (mating behaviour).Here I want to experimentally study the flexibility and constraints of rodent reproductive behaviour in response to predation risk at various life stages: 1) infanticide risk for nestlings (current reproductive investment) on mothers investment into mate search (future reproductive investment);2) predation risk for the mother on her investment into mate search (future reproductive investment) and 3) predation risk for the mother on her mating strategy (monandric or polyandric involving variation in genetic diversity of investment). In all experiments, individual variation in time allocation, physiological responses, space use and mating success will be monitored allowing quantifying both behavioural and fitness consequences. Experiments will be conducted in different spatial and temporal scales: behavioural observations in the laboratory and automated telemetry observations in semi-natural enclosures. Results of the experiments will give novel estimates of the general flexibility of reproductive behaviour and for the first time measure life-history trade-offs of reproduction and mortality risk for individuals in semi-natural settings. A potential contribution of adaptations of reproductive behaviour in a risky world to predator-prey dynamics can be investigated in a second funding phase..