Fox C W, Bush M L, Roff D A, Wallin W G
Department of Entomology, S-225 Agricultural Science Center North, University of Kentucky, Lexington, KY 40546-0091, USA.
Heredity (Edinb). 2004 Mar;92(3):170-81. doi: 10.1038/sj.hdy.6800383.
The age at which individuals die varies substantially within and between species, but we still have little understanding of why there is such variation in life expectancy. We examined sex-specific and genetic variation in adult lifespan and the shape of mortality curves both within and between two populations of the seed beetle, Callosobruchus maculatus, that differ in a suite of life history characters associated with adaptation to different host species. Mean adult lifespan and the shape of the logistic mortality curves differed substantially between males and females (males had lower initial mortality rates, but a faster increase in the rate of mortality with increasing age) and between populations (they differed in the rate of increase in mortality with age). Larger individuals lived longer than smaller individuals, both because they had lower initial mortality rates and a slower increase in the rate of mortality with increasing age. However, differences in body size were not adequate to explain the differences in mortality between the sexes or populations. Both lifespan and mortality rates were genetically variable within populations and genetic variance/covariance matrices for lifespan differed between the populations and sexes. This study thus demonstrated substantial genetic variation in lifespan and mortality rates within and between populations of C. maculatus.
个体死亡的年龄在物种内部和物种之间都有很大差异，但我们对预期寿命为何存在这种差异仍知之甚少。我们研究了成年寿命的性别特异性和遗传变异，以及两种绿豆象（Callosobruchus maculatus）种群内部和之间死亡率曲线的形状，这两种绿豆象在一系列与适应不同寄主物种相关的生活史特征上存在差异。成年寿命的平均值和逻辑斯蒂死亡率曲线的形状在雄性和雌性之间（雄性的初始死亡率较低，但随着年龄增长死亡率上升得更快）以及种群之间（它们在死亡率随年龄增长的上升速率上存在差异）有很大不同。体型较大的个体比体型较小的个体寿命更长，这既是因为它们的初始死亡率较低，也是因为随着年龄增长死亡率上升得较慢。然而，体型差异不足以解释性别或种群之间的死亡率差异。寿命和死亡率在种群内部都是遗传可变的，并且寿命的遗传方差/协方差矩阵在种群和性别之间有所不同。因此，这项研究证明了绿豆象种群内部和之间在寿命和死亡率方面存在大量遗传变异。
