ALTERNATIVE REPRODUCTIVE STRATEGIES IN MICROTUS

哺乳动物必须明智地将其可用的能量分配给 生殖需求和非生殖需求的竞争。 我们对 这种分配过程的性质，无论是代谢还是 神经内分泌学的 本提案的目的是了解更多 通过利用一种独特的自然发生的 野生啮齿类动物的变异。 一些温带种群 啮齿类动物包含基因不同的个体， 明显不同的生殖策略;一些个体依赖于 光周期来确定它们的年度生殖周期，而其他在 同样的种群忽略了这一线索，而是机会主义地繁殖， 有时甚至在冬天。 这是一项旨在阐明 遗传、行为、代谢和神经内分泌基础 替代策略使用田鼠属田鼠作为模型。 的 特别值得关注的是， 机会主义者在冬季既要生存又要繁殖。 首先，野生诱捕的田鼠将受到选择， 动物的不同遗传系，一种是繁殖光敏的， 一个是无响应/机会主义者。 第二，这两种反应 基因系的两个充满活力的挑战，冬季，粮食短缺， 温度低，会比较。 日长也是一个变量， 这些实验。 这里的核心问题是潜在的差异， 田鼠的生存能力和维持繁殖能力。 然而，其中包括各种具体的利益， 能量相关的行为和代谢适应，以及整个身体 能量平衡 第三，生殖重要性 两个遗传系对食物短缺和低水平的神经内分泌反应 温度会比较。 这项研究的结果之一将是一套坚实的原则， 在代谢过程中，吸收的能量被分配给 生殖需求和非生殖需求的竞争。 第二个结果将是 一套无与伦比的遗传工具， 了解这个重要的过程。

A mammal must judiciously partition its available energy among many competing reproductive and non-reproductive needs. We know little about the nature of this partitioning process, either metabolically or neuroendocrinologically. It is the intent of this proposal to learn much more about this process by exploiting a unique kind of naturally-occurring variation that occurs in wild rodents. Some temperate zone populations of rodents contain a mixture of genetically-different individuals that use markedly different reproductive strategies; some individuals rely on photoperiod to time their annual reproductive cycle while others in the same population ignore this cue, breeding opportunistically instead, sometimes even during the winter. This is a proposal to elucidate the genetic, behavioral, metabolic and neuroendocrine bases of these alternative strategies using voles of the genus Microtus as a model. Of particular concern will be the kinds of energetic adaptations that allow opportunists both to survive and reproduce during the winter. First, wild-trapped voles will be subjected to selection to develop two distinct genetic lines of animals, one reproductively-photoresponsive and one non-responsive/opportunistic. Second, the reactions of these two genetic lines to the two energetic challenges of winter, food shortage and low temperature, will be compared. Daylength will also be a variable in these experiments. Of core concern here are potential differences in the voles ability to survive and maintain their capacity to reproduce. Incorporated therein, however, are interests in a variety of specific energy-related behavioral and metabolic adaptations, as well as whole body energy balance. Third, the reproductively important neuroendocrine reactions of the two genetic lines to food shortage and low temperature will be compared. One result of this research will be a solid set of principles that pertain to the metabolic process wherein assimilated energy is allocated to competing reproductive and non-reproductive needs. A second result will be an unparalleled set of genetic tools with which to develop still greater understanding of this important process.