Khazaeli A A, Xiu L, Curtsinger J W
Department of Egology, Evolution and Behavior, University of Minnesota, St. Paul 55108, USA.
Genetica. 1996 Jul;98(1):21-31. doi: 10.1007/BF00120215.
Age-specific mortality rates were studied at two adult density levels in four inbred lines of Drosophila melanogaster. In experimental populations, adult densities were maintained at constant levels throughout the experiment by replacing dead flies with live, marked mutants. In control populations, densities declined naturally as the cohorts aged. For all experimental populations the best mortality model is the two-stage Gompertz model, with slower mortality acceleration at older ages. Flies in the experimental populations generally lived longer than flies in control populations, regardless of sex, genotype, or initial density level. The data demonstrate that deceleration of age-specific mortality rates at older ages is not caused by declining cohort densities. Mortality deceleration is a real phenomenon that raises serious questions about the evolution of senescence.
在四种黑腹果蝇近交系中，研究了两个成虫密度水平下的年龄特异性死亡率。在实验种群中，在整个实验过程中，通过用有标记的活突变体替代死亡果蝇，将成虫密度维持在恒定水平。在对照种群中，随着群体变老，密度自然下降。对于所有实验种群，最佳死亡率模型是两阶段冈珀茨模型，在老年时死亡率加速较慢。无论性别、基因型或初始密度水平如何，实验种群中的果蝇通常比对照种群中的果蝇寿命更长。数据表明，老年时年龄特异性死亡率的减速并非由群体密度下降所致。死亡率减速是一个真实现象，这对衰老的进化提出了严重问题。
