Life-history optimisation in response to climate change

应对气候变化的生活史优化

• 批准号: 2440361
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440361
• 关键词: Life; history; optimisation; response; climate

Predicting how climate change will affect populations is one of the major issues facing us today. In many ecosystems, the phenology of one species will influence the optimum timing of life-history events for species at higher trophic levels. In seasonal environments, consumers are selected to time energetically demanding activities, for instance reproduction, to coincide with a short period of favorable conditions, such as the peak in prey availability1,2. However, differential responses to environmental change may lead to phenological mismatches between species and potentially impact on individual fitness (e.g. offspring number) and population demography (e.g. population size)3,4,5. Therefore, determining the optimal annual timing of key life-history events in the context of environmental variation and understanding how closely individuals can track this are crucial for projecting population trends under climate change.The correct timing of an event relies on the optimal sequence of behavioral decisions preceding it, while considering the associated costs and benefits at each step. The trade-offs between different decisions are influenced by the individual's state, their previous actions as well as the environmental conditions they are faced with6. For instance, woodland passerines, such as tits in the Paridae family, maximize their reproductive success when the provisioning of young coincides with the peak in caterpillar abundance7,8. The optimal timing of the nestling stage is preceded by decisions about reproductive timing and effort including (1) the laying date, (2) the clutch size and (3) the incubation period. These traits are intricately linked through trade-offs and are cued by environmental factors9.10. For instance, in years with higher spring temperatures, females may respond plastically to (1) advance lay date and/or (2) reduce clutch size and/or (3) begin incubation before the last egg is laid in anticipation of an earlier caterpillar peak11,12,13. In this example, the quantity of offspring (smaller clutch size) may be traded for their quality (increased synchrony with resource).There is substantial variation between individuals in the extent to which they can adjust different aspects of their breeding cycle, thought to be linked to individual condition14,15. A large body of research has explored immune function-related costs of reproductive behavior as a mechanism mediating life-history trade-offs16, though these physiological traits are often difficult to measure and underpinned by complex pathways. On the other hand, plumage quality may be a more easily quantifiable currency underlying the trade-offs between, for instance, reproductive timing and moult rate17,18. Specifically, the insulating capacity of feathers has been suggested to drive the negative impacts of delayed breeding on overwinter survival and future reproductive success19. However, we need to better understand (1) the relationship between feather quality and its insulating properties, and (2) how plumage condition may mediate the effects of both reproductive timing (e.g. lay date) and reproductive investment (e.g. clutch size) on fitness (i.e. future survival and reproduction) during each stage of the breeding cycle.

预测气候变化将如何影响人口是我们今天面临的主要问题之一。在许多生态系统中，一个物种的物候会影响处于较高营养级的物种的生活史事件的最佳时间。在季节性环境中，消费者被选择为时间精力充沛的活动，例如繁殖，以符合短期的有利条件，如在猎物availability 1，2的高峰。然而，对环境变化的不同反应可能导致物种之间的物候不匹配，并可能影响个体适应度（例如后代数量）和种群人口统计学（例如种群规模）3，4，5。因此，在环境变化的背景下，确定关键生命史事件的最佳年度时间，并了解个体如何密切跟踪这一点，对于预测气候变化下的人口趋势至关重要。事件的正确时间取决于之前的行为决策的最佳顺序，同时考虑每个步骤的相关成本和收益。不同决定之间的权衡受到个人状态、他们以前的行为以及他们所面临的环境条件的影响。例如，林地雀形目，如山雀科家庭，最大限度地提高其繁殖成功时，供应的年轻人在毛虫丰度的高峰期相吻合7，8。雏鸟阶段的最佳时间是在决定繁殖时间和努力之前，包括（1）产蛋日期，（2）窝卵数和（3）孵化期。这些特征通过权衡而错综复杂地联系在一起，并受到环境因素的影响。例如，在春季温度较高的年份，雌性可能会对（1）提前产蛋日期和/或（2）减少窝卵数和/或（3）在最后一个蛋产下之前开始孵化，以期待更早的毛虫高峰11，12，13做出可塑性反应。在这个例子中，后代的数量（较小的窝卵数）可以用来换取它们的质量（增加与资源的同步性）。个体之间在调整繁殖周期的不同方面的程度上存在很大差异，这被认为与个体状况有关14，15。大量的研究已经探索了生殖行为的免疫功能相关成本，作为介导生命史权衡的机制16，尽管这些生理特征通常难以测量，并且由复杂的途径支撑。另一方面，羽毛质量可能是一个更容易量化的货币之间的权衡，例如，生殖时间和换羽率17，18。具体来说，羽毛的绝缘能力被认为是推迟繁殖对越冬生存和未来繁殖成功的负面影响。然而，我们需要更好地理解（1）羽毛质量与其绝缘性能之间的关系，以及（2）在繁殖周期的每个阶段，羽毛状况如何介导生殖时间（例如产蛋日期）和生殖投资（例如窝卵数）对适合度（即未来生存和繁殖）的影响。