CNRS UMR 7625, Laboratoire Écologie & Évolution, École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France.
Evolution. 2011 Oct;65(10):3013-20. doi: 10.1111/j.1558-5646.2011.01347.x. Epub 2011 Jul 14.
Postreproductive life span remains a puzzle for evolutionary biologists. The explanation of increased inclusive fitness through parental care after reproduction that applies for humans is unrealistic for many species. We propose a new selective mechanism, independent of parental care, which relies on the hypothesis that postreproductive life span can evolve as an insurance against indeterminacy: longer life expectancy reduces the risk of dying by chance before the cessation of reproductive activity. We demonstrate numerically that the duration of evolved postreproductive life span is indeed expected to increase with variability in life span duration. An unprecedented assay of 11 strains of the collembola Folsomia candida shows the existence of (1) postreproductive life span in the absence of parental care; (2) genetic variability in mean postreproductive life span and postreproductive life span variability itself; (3) strong genetic correlation between latter traits. This new explanation brings along the novel idea that loose canalization of a trait (here, somatic life span) can itself act as a selective pressure on other traits.
生殖后寿命仍然是进化生物学家的一个谜。对于人类来说，通过繁殖后的亲代照顾来解释包容性适合度的增加是不现实的，对于许多物种来说都是如此。我们提出了一种新的选择机制，与亲代照顾无关，该机制依赖于这样一种假设，即生殖后寿命可以作为一种抵御不确定性的保险而进化：更长的预期寿命降低了在生殖活动停止之前因偶然因素而死亡的风险。我们通过数值证明，进化后的生殖后寿命的持续时间确实预计会随着寿命持续时间的可变性而增加。对 11 个球甲科 Folsomia candida 品系进行的一项前所未有的测定表明，存在以下特征：（1）在没有亲代照顾的情况下存在生殖后寿命；（2）生殖后寿命平均值和生殖后寿命可变性的遗传变异性；（3）后两种特征之间存在强烈的遗传相关性。这个新的解释带来了一个新的想法，即一个特征（这里是体细胞寿命）的松散的 canalization 本身可以作为对其他特征的选择压力。
