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

9701209 Tessier衰老，通过动物随着年龄的增长而生理恶化来衡量，是当前许多研究的主题。 为什么衰老会发生，以及与衰老相关的潜在遗传机制也是大量研究的主题。 传统的实验室遗传学工作已经证实了许多理论工作。 然而，相对较少的科学家研究了野生种群中衰老的遗传变异，或者这种变异存在的生态环境。 拟议的研究将通过生命表实验和自然死亡率来源的详细描述来填补我们知识中的这些空白。 水蚤是一种常见的淡水甲壳类动物，将对其进行研究，因为它的生态学众所周知，而且它会克隆繁殖。 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，自然人口的老龄化率可以估计没有外来死亡率的干扰。 老龄化率可以与死亡率的实地估计数据进行比较。 死亡率的来源（例如，捕食，疾病，栖息地季节性），然后可以用来检查内在寿命（和其他老化指标）和预期的野生寿命之间的关系。 该研究还将测试理论预测，即快速衰老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），并寻找与衰老速度的权衡。 只有在生命早期存在相关优势（如加速生长）的情况下，高老龄化率才是可持续的。 相反，生命早期的不良繁殖或生长只有在动物寿命延长时才能持续。

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.