Blarer A, Doebeli M, Stearns S C
Institute of Zoology, University of Basel, Switzerland.
Proc Biol Sci. 1995 Dec 22;262(1365):305-12. doi: 10.1098/rspb.1995.0210.
Based on the predictions of two theories for the evolution of senescence, the 'antagonistic pleiotropy' and the 'mutation accumulation' theory, an age-specific increase in mortality and a decrease in fecundity are widely used criteria to diagnose senescence in natural, and laboratory populations. In this study we question the reliability of these criteria. Using a simple model we show that similar phenotypic patterns result from optimal life histories without senescence. With a tradeoff between reproduction and period survival, optimal life histories produce patterns of increasing mortality and decreasing fecundity as organisms age, even if the tradeoff does not deteriorate with age, so that we are not forced to invoke genetic effects such as antagonistic pleiotropy or accumulation of deleterious mutations to explain such patterns. Furthermore, if optimal life history theory is applied to senescent organisms, phenotypic patterns can result that are usually not associated with senescence. We conclude that the reliability of a diagnosis of senescence based on phenotypic patterns and the comprehension of the phenomenon senescence depends critically on understanding to what extent tradeoffs are determined by the effects of segregating genes.
基于衰老进化的两种理论——“拮抗多效性”理论和“突变积累”理论的预测，死亡率随年龄增长以及繁殖力下降是在自然种群和实验室种群中诊断衰老时广泛使用的标准。在本研究中，我们质疑这些标准的可靠性。通过一个简单的模型，我们表明，在没有衰老的最优生活史中也会产生类似的表型模式。在繁殖和时期存活之间存在权衡的情况下，最优生活史会随着生物体年龄增长产生死亡率增加和繁殖力下降的模式，即使这种权衡不会随年龄恶化，因此我们无需借助拮抗多效性或有害突变积累等遗传效应来解释此类模式。此外，如果将最优生活史理论应用于衰老生物体，可能会产生通常与衰老无关的表型模式。我们得出结论，基于表型模式诊断衰老的可靠性以及对衰老现象的理解，关键取决于理解权衡在多大程度上由分离基因的效应所决定。
