Adaptive Significance of Circadian Timing Systems in Wild, Free-Living Chipmunks

DeCoursey昼夜节律起搏器被认为对生物体的生存和遗传适应性具有高度适应性，因为它们在几乎所有动物的多种日常生理和行为功能中发挥作用。 然而，由于技术上的困难，目前还没有直接的测试来评估生物节律起搏器在野生物种中的生存价值。 本项目的目的是利用一个良好的啮齿动物昼夜节律模型来测试哺乳动物的主要昼夜节律起搏器，视交叉上核（SCN）的重要性。 该研究的基本原理是通过SCN损伤手术创建无时钟的野生种群的动物队列，然后比较和控制无时钟组。 研究对象是弗吉尼亚州彭布罗克市山湖生物研究站阿巴拉契亚南部荒野种群中的花栗鼠。 一项为期一年的试点研究已经证明了对野生捕获的个体的SCN进行损伤的可行性，将它们重新引入洞穴，然后通过定期诱捕普查、每日目视观察和跟踪无线电发射器项圈动物来记录选定的健身措施。 在拟议的研究中，所有4公顷网格的金花鼠将被永久性耳标和彩色珠子项链标记，以便目视观察。 然后将20只SCN损伤、20只假损伤和24只完整对照动物戴上放射性项圈，并进行为期两年的密切随访;健康指标将包括日常活动模式、死亡率、喂养成功率（通过体重、巢穴和核心领地防御证明）、繁殖成功率和冬眠行为。 与这些自由生活的个体平行，5只对照金花鼠和5只SCN损伤的金花鼠将在11月至4月的冬季在室外Hibernaculum设施中通过无线电遥测进行监测，以获得有关冬眠的额外信息，在此期间，野生金花鼠在地下基本上不活动，难以监测。

9603878 DeCoursey Circadian pacemakers are presumed to be highly adaptive for survival and for genetic fitness of organisms since they play a role in diverse daily physiological and behavioral functions of nearly all animals. No direct test has been made, however, to assess the survival value of circadian pacemakers in wild species, primarily due to the technical difficulties involved. The object of this project is to use a favorable rodent circadian model to test the importance of the primary mammalian circadian pacemaker, the suprachiasmatic nuclei (SCN). The rationale of the research is to surgically create clockless, arrhythmic cohorts of a wild population by SCN lesioning, then compare and control and clockless groups. The study system will be the chipmunks of a southern Appalachian wilderness population at Mountain Lake Biological Research Station, Pembroke, Virginia. A year-long pilot study has demonstrated the feasibility of lesioning the SCN of wild-caught individuals, reintroducing them back into their burrows, and then documenting selected measures of fitness by periodic trapping censuses, daily visual observations, and tracking of radiotransmitter-collared animals. In the proposed study, all chipmunks of a 4-hectare grid will be marked by permanent ear tags and colored bead necklaces for visual observation. Twenty SCN-lesioned, 20 sham-lesioned, and 24 intact control animals will then be radiocollared and followed intensely for a two-year period; measures of fitness will include daily activity patterns, mortality, feeding success as evidenced by body weight, den and core territory defense, reproductive success, and hibernation behavior. In parallel with these free-living individuals, 5 control chipmunks and 5 SCN-lesioned chipmunkds will be monitored by radiotelemetry during the winter months from November to April in an outdoor Hibernaculum facility to obtain additional information on hibernation during the time that wild chipmunks are largely inactive underground and di fficult to monitor.