DETERMINANTS OF EXTREME LONGEVITY IN A PLANT SPECIES

项目7：植物极端长寿的决定因素 衰老在人口统计学上被定义为生殖成熟后死亡率的增加。我们目前对死亡率模式的理解可能受到限制，因为大多数研究都是在实验室条件下使用寿命短的模式生物进行的。该项目使用了一种新的模型系统，具有相对较长的寿命和独特的生长和繁殖轨迹。这个项目的基础是一个30,000人的多年生植物物种Plantago lanceolata。早期研究的结果表明，成熟后的持续生长可能会使这个物种最大限度地减少，甚至逃避衰老过程。这一初步项目表明，死亡率有许多决定因素， 这个物种包括外在环境因素，空间位置，遗传，繁殖，队列历史，最重要的是个体的大小。这个新项目将把这种分析扩展到另一个群体和以后的几年。它将检验尺寸的重要性和年龄的最小重要性是否会持续到最新的年龄。将收集数据以测试我们的协变量回归模型中的一些假设，我们已经编写了该模型以探索该物种的年龄特异性死亡率。我们还有一个已经建立的披针叶松种群，它在温室的受控条件下已经生长了五年多。在自然环境中，很少有个体能活到这么晚，但在这些受保护的条件下，大多数种群都存活了下来，并开始显示出死亡率的上升。 这个受保护的种群提供了一个独特的机会来研究一个物种在极晚期的死亡率动态，它将检验这样一个假设，即衰老模式只在比个体在自然环境中生存的年龄晚得多的年龄才明显。

Project 7: Determinants of Extreme Longevity in a Plant Species Senescence is defined demographically as an increase in mortality after reproductive maturity. Our current understanding of mortality patterns may be limited by the fact that most studies have been made with short-lived model organisms under laboratory conditions. This project uses a new model system, with a relatively long lifespan and unique trajectories of growth and reproduction with age. At the foundation of this project is a population of 30,000 individuals of Plantago lanceolata, a perennial plant species. Results from an earlier study suggest that continued growth after maturity might allow this species to minimize, or even escape, the aging process. This preliminary project showed that there are many determinants of mortality in this species including extrinsic environmental factors, spatial location, genetics, reproduction, cohort history, and most importantly size of an individual. This new project will expand this analysis to another population and to later years. It will test whether the importance of size, and the minimal importance of age, will continue to the latest ages. Data will be collected to test some of the assumptions in our covariate regression model that we have written to explore age-specific mortality in this species. We also have an established population of P. lanceolata that has been growing for over five years under the controlled conditions of the greenhouse. Few individuals, in the natural environment, live to this late age but under these protected conditions, the majority of the population has survived and is beginning to show an increase in mortality. This protected population offers a unique opportunity to study the mortality dynamics of a species at extremely late ages and it will test the hypothesis that patterns of senescence are only apparent at ages that are much later than individuals would survive in their natural environment.