Reznick D, Buckwalter G, Groff J, Elder D
Department of Biology, University of California, Riverside, CA 92521, USA.
Exp Gerontol. 2001 Apr;36(4-6):791-812. doi: 10.1016/s0531-5565(00)00241-2.
Model organisms like Drosophila melanogaster or Caenorhabditis elegans have revealed genes that influence senescence and the evolvability of senescence. We are interested instead in evaluating why and how senescence evolves in natural populations. To do so, we are taking the ecological geneticist's perspective of comparing natural populations that differ in factors that are predicted to influence the evolution of senescence and are evaluating whether senescence has evolved in the predicted fashion. We are also manipulating the environment to evaluate more directly the evolution of senescence. Guppies (Poecilia reticulata) are found in streams throughout the Northern Range mountains of Trinidad. Natural populations experience large differences in mortality rate as a consequence of the predators with which they co-occur. We have already shown, both with comparative studies and manipulations of the distribution of guppies and their predators, that the early life history evolves very rapidly in response to these differences in mortality. For example, high adult mortality rates select for individuals that develop more rapidly, produce their first litter of young at an earlier age, and devote more of their available resources to reproduction for the remainder of their lives. These changes were predicted by independently derived theory. Aspects of this same theory also predict how the late life history and senescence should evolve. Specifically, theory predicts that the populations that experience low mortality rates should also experience delayed senescence and longer life spans relative to those that experience high mortality rates. We are currently evaluating these predictions with representatives from two high-predation and two low-predation environments. Our presentation will focus on our pilot study, which evaluated life span, lifetime reproduction, and the patterns of aging in our laboratory populations. We will also report on the progress in our ongoing comparative studies of senescence in natural populations.
像黑腹果蝇或秀丽隐杆线虫这样的模式生物已经揭示了影响衰老和衰老进化能力的基因。相反，我们感兴趣的是评估衰老在自然种群中为何以及如何进化。为此，我们采用生态遗传学家的视角，比较在预计会影响衰老进化的因素上存在差异的自然种群，并评估衰老是否以预测的方式进化。我们还在操纵环境，以更直接地评估衰老的进化。孔雀鱼（孔雀鱼）分布在特立尼达北部山脉的溪流中。由于与其共生的捕食者，自然种群的死亡率存在很大差异。我们已经通过比较研究以及对孔雀鱼及其捕食者分布的操纵表明，早期生活史会因这些死亡率差异而非常迅速地进化。例如，高成年死亡率会选择那些发育更快、更早产下第一窝幼崽，并在余生中将更多可用资源投入繁殖的个体。这些变化是由独立推导的理论预测的。同一理论的各个方面也预测了晚年生活史和衰老应该如何进化。具体来说，理论预测，与高死亡率种群相比，低死亡率种群也应该经历延迟衰老和更长的寿命。我们目前正在用来自两个高捕食环境和两个低捕食环境的代表来评估这些预测。我们的报告将重点关注我们的试点研究，该研究评估了我们实验室种群的寿命、终生繁殖和衰老模式。我们还将报告我们正在进行的自然种群衰老比较研究的进展情况。
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