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.

合作研究：压力和营养对鸟类繁殖的相互影响孟菲斯大学阿赫博尔德生物站斯蒂芬J。为了在有利生存的条件下繁殖后代，大多数生物都依赖于各种环境线索。PI使用了观察和实验研究相结合的方法来证明食物的数量和质量会影响繁殖的时间。在附近的阿赫博尔德生物站（ABS），生活在郊区栖息地的佛罗里达灌丛松鸦（Aphelocoma coerulescens）可以随意获得人类提供的食物，它们的繁殖总是比生活在荒地栖息地的松鸦早。在荒地，补充不同脂肪和蛋白质含量的饮食证实了这些营养素协同作用，以促进育种。给予高脂肪/高蛋白（HFHP）饮食的鸟类比对照组和补充高脂肪/低蛋白饮食的松鸦更早产蛋，增加母体对蛋的分配，并增加后代的存活率。此外，PI发现，相对于对照组，HFHP补充成年鸟的越冬存活率有明显增加的趋势（即使鸟类仅在1月至3月补充HFHP）。重要的是，郊区和HFHP荒地松鸦的皮质酮（CORT）水平也低于荒地对照组。由于CORT可以对生殖轴产生负面影响，因此CORT和营养之间的联系表明生殖启动的独特机制。PI开发了一个新的模型，展示了资源如何影响压力（CORT），这反过来又影响了育种的时机。与其他模型不同，这预测了提前的繁殖时间和减少的年间变化-与经验观察一致。在繁殖季节的早期，鸟类可能会因食物供应减少而感到压力。虽然它们可能被其他线索（如光周期）“生殖启动”，但高水平的CORT抑制生殖。但随着食物变得更可预测或质量更好，压力水平降低，释放抑制，允许繁殖发生。现场和圈养的研究将被用来测试的假设，与资源质量和/或可预测性的压力是生理机制，环境线索转化为生殖决策。郊区和HFHP补充的松鸦将植入CORT，以确定它是否会延迟自由进食的雌性繁殖。为了了解CORT的去除是否会导致生殖轴的早期激活和提前产蛋，将在ABS处阻断未补充CORT的松鸦。PI还将通过检查饮食，压力和繁殖时间对鸡蛋大小，后代发育以及短期和长期生存的相互作用来评估资源可用性的最终影响。通过对蓝鸟的圈养研究，PI将进一步研究饮食与压力和繁殖之间的相互作用。这些研究允许对食物处理的内分泌反应进行连续采样。PI将比较松鸦的生殖激素和应激激素，这些激素在提供食物的可预测性方面不同。此外，夜间暴露在郊区的光线可能会刺激生殖轴。这将通过比较在日常周期的黑暗阶段暴露于低水平光照的松鸦与不暴露于低水平光照的鸟类的一套生理参数来进行测试。压力，环境资源和繁殖之间的相互作用尚未在自由生活的物种进行彻底研究，可能是鸟类繁殖时间的关键。郊区部分强调了与全球城市化模式相关的快速环境变化如何影响自然选择的系统，并说明了潜在的后果。佛罗里达灌丛松鸦是一个下降的物种，并可能作为一个重要的模式，为越来越多的其他物种从许多类群，是或将面临类似的挑战，由于不断失去栖息地，在面对越来越多的人类使用。首先，佛罗里达灌丛鸦是一种受威胁的物种，这项研究可能会提供减缓数量下降的方法。第二，收集到的技术和信息可以用来改善其他物种的减少。第三，压力对生物体（包括人类）的许多方面都有深远的负面影响。这项研究（和相关项目）将考虑压力，营养，生殖，免疫功能和生存之间的联系：所有这些都具有重要的跨物种影响。