Collaborative Research: Interactive Effects of Stress and Nutrition on Reproduction in Birds

合作研究：压力和营养对鸟类繁殖的交互影响

• 批准号: 0346328
• 负责人: Stephan Schoech
• 金额: $ 43.7万
• 依托单位: University of Memphis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-15 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0346328&HistoricalAwards=false
• 关键词: Collaborative; Research; Interactive; Effects; Stress

Collaborative Research: Interactive Effects of Stress and Nutrition on Reproduction in BirdsStephan J. Schoech & Reed BowmanUniversity of Memphis & Archbold Biological StationCorrectly timing breeding is essential for animals to maximize their fitness. To produce young when conditions favor their survival, most organisms rely on a variety of environmental cues. The PIs have used a combination of observational and experimental studies to demonstrate that food quantity and quality influence timing of breeding. Florida Scrub-Jays (Aphelocoma coerulescens) in suburban habitats with access to ad libitum human-provided food always breed earlier than jays in wildland habitat at nearby Archbold Biological Station (ABS). In wildlands, supplementation with diets that differ in fat and protein content confirm that these nutrients act in synergy to advance breeding. Birds given high fat/high protein (HFHP) diets lay earlier than controls and jays supplemented with high fat/low protein diet, increase maternal allocation to eggs, and increase survival of offspring. Additionally, the PIs found a strong trend for increased over-winter survival of HFHP-supplemented adults relative to controls (even though birds are only supplemented from Jan-Mar). Importantly, both suburban and HFHP wildland jays also had lower levels of corticosterone (CORT), the avian stress hormone, than wildland controls. Because CORT can negatively affect the reproductive axis, the link between CORT and nutrition suggests a unique mechanism underlying the initiation of reproduction. The PIs have developed a novel model demonstrating how resources influence stress (CORT), which in turn influences timing of breeding. Unlike other models, this predicts both advanced timing of breeding and reduced between-year variation - consistent with empirical observations. Very early in the breeding season, birds may be stressed by reduced food availability. Although they may be "reproductively primed" by other cues, such as photoperiod, high levels of CORT inhibit reproduction. But as food become more predictable or of better quality, stress levels are reduced, releasing the inhibition, allowing breeding to occur. Field and captive studies will be used to test the hypothesis that stress associated with resource quality and/or predictability is the physiological mechanism by which environmental cues are translated into reproductive decisions. Suburban and HFHP-supplemented jays will be implanted with CORT to determine if it delays reproduction in females with access to ad libitum food. To learn whether the removal of CORT results in earlier activation of the reproductive axis and advanced laying, CORT will be blocked in unsupplemented jays at ABS. The PIs also will evaluate the ultimate effects of resource availability by examining the interactive effects of diet, stress, and time of breeding on egg size, offspring development, and short- and long-term survival. Using captive studies on Blue Jays, the PIs will examine further the interactions between diet and stress and reproduction. These studies allow serial sampling of endocrine responses to food treatments. The PIs will compare reproductive and stress hormones in jays that differ in the predictability in which food is provided. In addition, nocturnal light exposure in the suburbs may be stimulatory to the reproductive axis. This will be tested by comparing a suite of physiological parameters in jays that are exposed to low levels of light during the dark phase of the daily cycle with birds that are not. The interactions between stress, environmental resources, and reproduction have not been thoroughly investigated in free-living species and may be critical in how birds time reproduction. The suburban component underscores how rapid environmental change associated with global patterns of urbanization can influence naturally-selected systems, and illustrates the potential consequences. Florida Scrub-Jays are a declining species and may serve as an important model for an increasing number of other species from many taxa that are or will face similar challenges due to continued loss of habitat in the face of increasing human usage.This project will have benefits at multiple levels. First, Florida Scrub-Jays are a threatened species and this research may provide ways in which the decline in numbers may be slowed. Second, techniques and information gleaned may be used to ameliorate declines in other species. Third, stress has profound negative impacts upon many aspects of an organism's (humans included!) health, and this research (and associated projects) will consider links between stress, nutrition, reproduction, immune function, and survivorship: all of which have important cross-species implications.

协作研究：压力和营养对孟菲斯和大街生物站的Birdsstephan J. Schoech＆Reed Bowmanuniversity的互动效果对动物最大化其适应性是必不可少的。在条件有利于生存的情况下产生年轻人，大多数生物都依赖各种环境提示。 PI使用了观察性研究和实验研究的组合来证明食物数量和质量会影响育种的时机。郊区栖息地中的佛罗里达灌木jays（Aphelocoma coerulescens）在附近的Archbold生物站（ABS）的Wildland栖息地（ABS）的Jays中，可以随意提供人为提供的食物。在野外，补充脂肪和蛋白质含量不同的饮食证实，这些营养素在协同作用中起着提高繁殖的作用。高脂肪/高蛋白质（HFHP）饮食的鸟类比对照组和jays含量早，并补充了高脂肪/低蛋白质饮食，增加了母体对卵的分配，并增加了后代的存活率。此外，PIS发现，相对于对照组相对于对照组相对于HFHP的成年人的过冬存活增加的强烈趋势（即使鸟类仅补充了Jan-Mar）。重要的是，郊区和HFHP Wildland Jays的皮质酮（Cort）（Cort），禽流压力激素的水平也低于Wildland Controls。由于Cort可能会对生殖轴负面影响，因此Cort和营养之间的联系表明了繁殖开始的独特机制。 PI开发了一个新颖的模型，展示了资源如何影响压力（CORT），从而影响育种时机。与其他模型不同，这既可以预测繁殖的高级时机，又可以减少年之间的变化 - 与经验观察一致。在繁殖季节的早期，鸟类的供应量降低可能会强调鸟类。尽管它们可能被其他提示“生殖启动”，例如光周期，但高水平的Cort抑制了繁殖。但是，随着食物变得越来越可预测或质量更好，压力水平降低，释放抑制作用，从而允许繁殖。现场和圈养研究将用于检验以下假设：与资源质量和/或可预测性相关的压力是将环境线索转化为生殖决策的生理机制。郊区和补充HFHP的Jays将被植入Cort，以确定它是否会延迟获得征用征用食物的女性的繁殖。为了了解去除Cort是否会导致生殖轴和高级铺设的早期激活，Cort将在ABS处被封锁。 PI还将通过检查饮食，压力和繁殖时间对鸡蛋大小，后代发展以及短期和长期生存的互动效果来评估资源可用性的最终影响。使用对蓝鸟的圈养研究，PI将进一步研究饮食与压力与繁殖之间的相互作用。这些研究允许对食物治疗的内分泌反应序列采样。 PI将比较JAY中的生殖和应力激素，这些荷尔蒙在提供食物的可预测性方面有所不同。另外，郊区的夜间光线暴露可能是生殖轴的刺激性。这将通过比较Jays中的一组生理参数来测试，这些生理参数在日常循环的黑暗阶段与没有的鸟类相比，这些参数暴露于低水平的光线。压力，环境资源和繁殖之间的相互作用尚未在自由生活物种中进行彻底研究，对于鸟类的时间繁殖可能至关重要。郊区组件强调了与全球城市化模式相关的环境变化如何影响自然选择的系统，并说明了潜在的后果。佛罗里达州的磨砂jays是一个下降的物种，可以作为来自许多分类单元中越来越多的其他物种的重要模型，因为面对人类使用的增加，由于持续的栖息地而持续丧失了栖息地。首先，佛罗里达州的磨砂日是一个受威胁的物种，这项研究可能会提供数量下降的方法。其次，可以使用收集的技术和信息来改善其他物种的下降。第三，压力对生物体的许多方面（包括人类的健康！）具有深远的负面影响，这项研究（及相关项目）将考虑压力，营养，繁殖，免疫功能和生存之间的联系：所有这些都有重要的跨物种含义。