Biodemography and senescence in long-lived painted turtles

描述(申请人提供)：为什么我们会衰老？这个问题引起了许多人的兴趣，也许是从我们人类诞生以来。值得注意的是，最近对海龟的研究没有发现人口老龄化的证据，即没有死亡和生殖老化。理论预测了衰老应该在什么情况下进化，这意味着这种衰老可能在进化上是不稳定的，它的发生依赖于背景。虽然理论上的预测已经在受控条件下的短寿命生物中得到了证实，但我们对野生长寿命生物衰老的生态学和进化缺乏了解，因为野生生物是在那里进化的。此外，进化上保守的分子网络是广泛的动物分类群(果蝇、老鼠、线虫)衰老的基础。在实验室模型之外，这种遗传和细胞机制是否以及如何导致死亡和生殖衰老尚不清楚。在特殊类群中量化衰老和这种衰老的进化、生态和生理决定因素将对衰老的进化和持久性及其与其他生活史特征的共同调节产生有价值的见解。我们将调查野生彩龟种群衰老的进化、生态学和遗传学的关键方面，自1988年以来一直被详细研究。我们将回答以下问题。1)这些毛虫是否表现出与年龄相关的生殖下降和死亡率上升，这是衰老的证据？2)性别之间是否存在差异，以及早年经历对晚年死亡率和生育轨迹是否存在长期影响？3)性别差异和早年对生育率的影响是否取决于背景？4)后代寿命是否与母亲的年龄或母方和父方的基因呈正相关，从而表明寿命的遗传？5)特定年龄的生理特征(特别是基因表达和线粒体能量学)是否类似于哺乳动物和模式遗传生物的死亡率和繁殖轨迹？我们将通过协调一致的实验和分析方法来解决这些问题。过去24年积累的现有信息学和基于收藏的资源，包括TurtleBase--一个包含与数百只海龟和鸟巢相对应的综合生态、环境、进化和遗传信息的数据库--将为建立老龄化生物人口学模型的分析管道提供投入。重要的是，我们地面上的海龟种群中有已知年龄的个体，从幼龟到最长寿命(大约25岁)。这些个体的样本与我们存档的组织和DNA库结合在一起，将使我们能够独特地测试这些重要的问题。

DESCRIPTION (provided by applicant): Why do we senesce? This question has intrigued many, perhaps since the dawn of our species. Remarkably, recent work on turtles has detected no evidence of demographic senescence, i.e. - no mortality and reproductive aging. Theory predicts the circumstances under which aging should evolve, implying that such senescence may be evolutionarily labile and its occurrence context-dependent. While predictions from theory have been borne out in short-lived organisms under controlled conditions, our understanding of the ecology and evolution of senescence in long-lived organisms in the wild, where it evolved, is lacking. Moreover, evolutionarily conserved molecular networks underlie aging in a wide array of animal taxa (fruit flies, mice, nematode worms). Whether and how such genetic and cellular mechanisms underlie mortality and reproductive senescence outside of the realm of laboratory models remains unknown. Quantifying aging and the evolutionary, ecological, and physiological determinants of such senescence in exceptional taxa will yield valuable insights into the evolution and persistence of senescence, and its co-regulation with other life-history traits. We will investigate key aspects of the evolution, ecology and genetics of aging in a wild population of painted turtles (Chrysemys picta), which has been studied in detail since 1988. We will answer the following questions. 1) Do these C. picta exhibit age-related declines in reproduction and increases in mortality, which is evidence for senescence? 2) Are there differences between the sexes and are there long-lasting impacts of early- age experiences on late-life mortality and fertility trajectories? 3) Are sex differences and early-life impacts on aing rates context dependent? 4) Is offspring lifespan positively related to maternal age or maternal and paternal genotype, thereby suggesting the inheritance of lifespan? 5) Do age-specific physiological profiles (specifically, gene-expression and mitochondrial energetics) underlie mortality and reproduction trajectories similar to mammals and model genetic organisms? We will address these questions with coordinated experimental and analytical approaches. Existing informatics and collections-based resources accumulated over the past 24 yrs., including TurtleBase - a database comprising integrated ecological, environmental, evolutionary, and genetic information corresponding to hundreds of turtles and nests - will provide the input to an analytical pipeline for modeling the biodemography of aging. Importantly, our on-the-ground turtle population has individuals of known age ranging from hatchling to maximum lifespan (ca. 25 yrs.). Samples of these individuals combined with our archived tissue and DNA bank will be leveraged to render us uniquely able to test these important questions.