ALTERNATIVE REPRODUCTIVE STRATEGIES IN MICROTUS

哺乳动物必须明智地将其可用能量分配给许多 相互竞争的生殖和非生殖需求。我们对此知之甚少 这种分割过程的性质，无论是新陈代谢还是 神经内分泌学。这项建议的目的是要学到很多东西。 通过利用一种独特的自然发生的 发生在野生啮齿动物身上的变异。一些温带种群 啮齿动物包含一群遗传上不同的个体，它们使用 明显不同的生殖策略；一些个体依赖于 光周期对它们的年度生殖周期进行计时，而其他在 同样的种群忽视了这一暗示，转而机会主义地繁殖， 有时甚至在冬天也是如此。这是一项旨在澄清 它们的遗传、行为、代谢和神经内分泌基础 以田鼠属田鼠为模型的替代策略。的 特别关注的将是那种能量适应，从而允许 机会主义者在冬季既能生存又能繁殖。 首先，将对野生诱捕的田鼠进行选择，以培育出两只 不同的动物遗传系，一种繁殖能力强，对光敏感和 一个没有反应的/机会主义的。第二，这两个人的反应 遗传系应对冬季的两个能源挑战，粮食短缺和 低温，将进行比较。白昼长度也将是 这些实验。这里的核心问题是 田鼠生存和维持繁殖能力的能力。 然而，其中包含的是各种具体的 与能量相关的行为和代谢适应，以及全身适应 能量平衡。第三，生殖方面的重要性 两个基因系对食物短缺和低摄入量的神经内分泌反应 温度将被比较。 这项研究的结果之一将是一套坚实的原则， 代谢过程中吸收的能量分配给 相互竞争的生殖和非生殖需求。第二个结果将是 一套无与伦比的遗传工具，用来发展更大的 了解这一重要过程。

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.