Dissertation Research: A Phylogenetic Approach to the Evolution of Senescence in Natural Populations

9701209特西尔衰老是目前许多研究的主题，它是通过动物随着年龄的增长而产生的生理退化来衡量的。衰老发生的原因以及与衰老相关的潜在遗传机制也是相当多的研究课题。传统的实验室基因研究已经证实了大部分理论工作。然而，相对较少的科学家研究了野生种群衰老的遗传变异，或这种变异存在的生态背景。拟议的研究将通过生命表实验和对自然死亡来源的详细描述来解决我们知识中的这些差距。水蚤是一种常见的淡水甲壳类动物，由于其生态已为人所知，并将进行克隆繁殖，因此将被研究。这种繁殖模式允许在实验室中对自然遗传变异进行采样，在实验室中可以在受控条件下构建生命表。因此，可以在不受外部死亡率干扰的情况下估计自然人口的老龄化速度。老龄化速度可以与现场估计的死亡率数据进行比较。死亡来源(如捕食、疾病、栖息地季节性)可用来研究固有寿命(和其他老龄化指标)与预期野生寿命之间的关系。这项研究还将检验理论预测，即快速老龄化在某些生态环境中可能间接有利。研究人员将描述早期生活史特征(例如，生长、成熟)，并寻找与老龄化速度的权衡。只有在生命早期存在相关优势的情况下，高老龄化才应该是可持续的，比如加速增长。相反，生命早期的不良繁殖或生长只有在动物通过更长的寿命受益的情况下才是可持续的。

9701209 Tessier Aging, as measured by the physiological deterioration of animals as they grow older, is the subject of much current research. Why aging occurs and what underlying genetic mechanisms are associated with aging are also topics of considerable research. Traditional laboratory genetic work has confirmed much of the theoretical work. However, relatively few scientists have examined genetic variation of aging in wild populations, or the ecological context in which this variation exists. The proposed research will address these gaps in our knowledge through life table experiments and detailed descriptions od sources of natural mortality. Daphnia, a common freshwater crustacean, will be studied because its ecology is well known and it will reproduce clonally. This mode of reproduction allows sampling of the natural genetic variation in the lab, where life tables can be constructed under controlled conditions. Thus, rates of aging for natural populations can be estimated without interference from extrinsic mortality. Aging rates can be compared to data from field estimates of mortality rates. Sources of mortality (e.g., predation, disease, habitat seasonality) can then be used to examine the relationship between intrinsic lifespan (and other aging indicators) and the expected wild lifespan. The research will also test theoretical predictions that rapid aging could be indirectly advantageous in certain ecological contexts. The investigators will characterize early life history traits (e.g. growth, maturation) and look for tradeoffs with rates of aging. A high rate of aging should be sustainable only if there are correlated advantages early in life, such as accelerated growth. Conversely, poor reproduction or growth early in life should be sustainable only if it benefits an animal through longer life.