A new theory of clutch size evolution: Consequences of morphology at fledging on mobility and survival interacting with parental energy expenditure (FMR)

窝数进化的新理论：雏鸟形态对活动性和生存的影响与父母能量消耗（FMR）相互作用

• 批准号: 1349178
• 负责人: Thomas Martin
• 金额: $ 53.65万
• 依托单位: University of Montana
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-15 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349178&HistoricalAwards=false
• 关键词: new; theory; clutch; size; evolution

How hard should parents work to raise offspring, and how does this work effort influence the number and survival of offspring that parents attempt to raise? These are questions that have intrigued scientists for more than a century, and have major implications for population dynamics of wild animals. These questions have been highlighted among songbirds because species vary extensively in the number of young that parents attempt to raise. Even among species that breed in the same habitat, such as high elevation riparian habitat in Arizona where work will be conducted, species vary extensively in the number of offspring they attempt to raise. For example, a green-tailed towhee in that habitat typically lays 3 or 4 eggs, a red-faced warbler lays 4 or 5 eggs, while a mountain chickadee may lay 8 eggs. A new theory to explain this variation based on risk of mortality to offspring and parents is proposed and this grant will fund tests of the new theory. Species differ in the risk of their young being eaten by predators, with the open cup nests of the towhee or warbler experiencing high predation, while the cavity nests of chickadees experience very low risk of predation. These differences in predation risk affect how long the young stay in the nest; species like the towhee and warbler leave their risky nest 8 to 11 days after hatch, while chickadees do not leave their safe cavity nest until 20 to 22 days after hatch. As a result, the towhee and warbler young cannot fly when they leave their nest, while the chickadees are fully flight capable when they leave. These differences in developmental state of the young when they leave the nest also potentially affect how quickly they start feeding themselves, with the chickadees potentially feeding themselves within a few days after leaving the nest, while the towhee may take 3 weeks to develop this ability. Potentially, towhee parents must work much harder for each young to provide all their food compared with the chickadee where young almost immediately start obtaining some of their own food and can follow parents to reduce their travel. The extent to which parents are willing to work differs among species depending on their risk of mortality over their annual cycle. Taken together, these effects may explain why species differ in the number of young they attempt to raise, and has critical consequences for population dynamics of species. The proposed work will use observational and experimental approaches to testing these hypotheses.The fledgling period (after offspring leave the nest) is a critical period for demography, but interspecific variation in survival is unknown and documentation will aid understanding of population vulnerabilities to changing environmental conditions. Given the documented economic and aesthetic importance of birding to society, this conservation knowledge is important. Three graduate students whose thesis research will be supported by this project will be trained. Each year, 1 technician and 6 undergraduates will be trained in field techniques and the conduct of science, as well as 8 undergraduates from across disciplines (in and outside of biology) to transcribe videos of parental behaviors. The latter provides outreach to engage diverse students in scientific principles. Students will be educated through discussion sessions that will be used to teach the scientific principles for the work being conducted. To identify possible recruits, we will use broad advertising approaches to further enhance the diversity of social and cultural groups from which we can recruit. Finally, nests provide a rich source of video opportunities to demonstrate differences among species in social interactions, as well as intriguing videos of predation events. The researcher started obtaining short, high definition videos to develop an educational series on parental and offspring behaviors and predation events to put on YouTube for public outreach. PBS Nature is filming a documentary on nest architecture and avian family life that will include footage at the focal field site to further increase public outreach.

父母应该付出多大的努力来抚养后代，这项工作对父母试图抚养的后代的数量和存活率有何影响？这些问题引起了科学家一个多世纪的兴趣，并对野生动物的种群动态具有重大影响。这些问题在鸣禽中得到了强调，因为在父母试图抚养的幼鸟数量上，物种的差异很大。即使在同一栖息地繁殖的物种，比如将进行研究的亚利桑那州高海拔河岸栖息地，物种在试图饲养的后代数量上也存在很大差异。例如，在那个栖息地，一只绿尾山雀通常产3到4个蛋，一只红脸林莺产4到5个蛋，而一只山雀可能产8个蛋。根据后代和父母的死亡风险，提出了一种解释这种变异的新理论，这笔拨款将用于测试这一新理论。不同物种的幼崽被捕食者吃掉的风险不同，趾头或林莺的开放杯状巢经历了高度的捕食，而山雀的洞穴巢经历了非常低的捕食风险。捕食风险的这些差异会影响幼鸟在巢中停留的时间；像趾头和莺这样的物种在孵化后8到11天就离开了危险的巢，而山雀直到孵化后20到22天才离开安全的洞穴。因此，小山雀和林莺在离开鸟巢时不能飞行，而山雀离开鸟巢时完全有飞行能力。幼鸟在离开鸟巢时发育状态的这些差异也可能影响它们开始自己进食的速度，山雀可能会在离开鸟巢后的几天内自己进食，而山雀可能需要3周的时间才能发展这种能力。潜在地，双胞胎父母必须更加努力地为每一只幼鸟提供所有的食物，而不是山雀，因为在山雀中，幼崽几乎立即开始获取自己的一些食物，并且可以跟随父母减少旅行。父母愿意工作的程度因物种的不同而不同，这取决于它们在年度周期中的死亡风险。总而言之，这些效应可能解释了为什么物种在试图饲养的幼虫数量上存在差异，并对物种的种群动态产生关键影响。这项拟议的工作将使用观察和实验的方法来验证这些假说。羽化期(后代离开巢后)是人口学的关键时期，但生存的种间差异是未知的，记录将有助于理解种群对不断变化的环境条件的脆弱性。考虑到观鸟对社会的经济和美学重要性，这种保护知识是重要的。将培训三名研究生，他们的论文研究将得到该项目的支持。每年，将有1名技术员和6名本科生接受现场技术和科学行为方面的培训，以及来自不同学科(生物学内外)的8名本科生转录父母行为的视频。后者提供外展，让不同的学生参与到科学原理中来。学生将通过讨论来教育学生，这些讨论将被用来教授正在进行的工作的科学原则。为了寻找可能的招聘人员，我们将使用广泛的广告方法，进一步增加我们可以招聘的社会和文化群体的多样性。最后，鸟巢提供了丰富的视频资源来展示不同物种在社会互动中的差异，以及有趣的捕食事件视频。这位研究人员开始获取短小的高清视频，以开发一系列关于父母和后代行为以及捕食事件的教育系列，并将其发布到YouTube上，用于公共宣传。PBS自然正在拍摄一部关于鸟巢建筑和鸟类家庭生活的纪录片，其中将包括在焦点现场的镜头，以进一步扩大公众宣传。