ENVIRONMENT, BEHAVIOR, AND REPRODUCTION

拟议研究的总体目标是制定一个更加 啮齿动物季节性繁殖调控的综合模型。 更具体地说，本提案的目标有两个方面：（1） 更精确地识别单独或协同作用的外部线索 以光周期调节季节性繁殖的雄性鹿鼠和草原 田鼠，（2）确定季节性的相对成本和效益 生殖静止期提出了一些析因实验， 研究四个环境因素（光周期， 温度、食物质量和食物量）对生殖功能的影响。 以往关于控制啮齿动物季节性繁殖的研究主要有 着重于光周期（日长）对育种的影响 在保持在温和的实验室环境温度下的动物中， 自由获取食物和水。然而，有相当一部分鹿 老鼠和草原田鼠对抑制性光周期没有反应， 动物在野外表现出季节性的繁殖模式。数据从这些 和其它农业害虫种类（例如，、褐腹田鼠M. pinetorum）支持日长线索可能不足的论点 或在调节季节性繁殖方面意义甚微， 小而投机的繁殖者一些鹿鼠个体抑制 繁殖时，环境温度低，而其他小鼠 只有当食物摄入量减少时才会受到影响。冬季繁殖的啮齿动物 似乎比处于繁殖静止期的动物更有优势， 可能的繁殖成功。维持这种关系必须付出代价， 生殖系统在冬季提出了几个实验， 评估小型啮齿动物冬季繁殖的成本和收益。 外在和社会因素对代谢率的影响， 将评估体温调节行为。拟议的研究将 提供数据，以更全面地了解监管的层次结构 外在线索 这些研究将提供新的概念视角的季节性 繁殖啮齿动物使用自然选择的啮齿动物种群， 而不是高度近亲繁殖的物种， 环境因素，而不是传统的一个或两个，应该允许 新的，生态相关的声明，关于控制季节性 生殖

The general goal of the proposed studies is to develop a more comprehensive model of the regulation of seasonal breeding in rodents. More specifically, the goals of this proposal are two-fold: (1) to identity more precisely the external cues that act alone or in concert with photoperiod to regulate seasonal breeding male deer mice and prairie voles, and (2) to ascertain the relative costs and benefits of seasonal reproductive quiescence. A number of factorial experiments are proposed to study the interactive effects of four environmental factors (photoperiod, temperature, food quality, and food quantity) on reproductive function. Previous studies on the control of rodent seasonal breeding have primarily focused upon the role of photoperiod (day length) influences upon breeding in animals maintained in mild laboratory ambient temperatures with ad libitum access to food and water. However, a substantial minority of deer mice and prairie voles fail to respond to inhibitory photoperiods; these animals display seasonal breeding patterns in the field. Data from these and other agricultural pest species (e.g., Microtus ochrogaster, M. pinetorum) support the contention that day length cues may be insufficient or of minimal significance in the regulation of seasonal reproduction in small, opportunistic breeders. Some individual deer mice inhibit reproduction when ambient temperatures are low, whereas other mice are affected only if food intake is reduced. Winter breeding rodents would appear to have an advantage over reproductively quiescent animals in terms of possible breeding successes. There must be costs to maintaining the reproductive system during the winter. Several experiments are proposed to evaluate the costs and benefits of winter reproduction in small rodents. The effects of extrinsic and social factors on metabolic rates and thermoregulatory behavior will be assessed. The proposed studies will provide data to understand more completely the hierarchy of regulatory extrinsic cues. These studies will provide new conceptual perspectives of seasonally breeding rodents. The use of naturally selected populations of rodents, rather than highly inbred species and the manipulation of several environmental factors, instead of the traditional one or two, should allow new, ecologically relevant statements about the control of seasonal reproduction.