Data from: Slow development as an evolutionary cost of long life

Life-history theory predicts a trade-off between early-life fitness and
life span. While the focus traditionally has been on the fecundity-life
span trade-off, there are strong reasons to expect trade-offs with growth
rate and/or development time. We investigated the roles of growth rate and
development time in the evolution of life span in two independent
selection experiments in the outcrossing nematode Caenorhabditis remanei.
First, we found that selection under heat-shock leads to the evolution of
increased life span without fecundity costs, but at the cost of slower
development. Thereafter, the putative evolutionary links between
development time, growth rate, fecundity, heat-shock resistance and life
span were independently assessed in the second experiment by directly
selecting for fast or slow development. This experiment confirmed our
initial findings, since selection for slow development resulted in the
evolution of long life span and increased heat-shock resistance. Because
there were no consistent trade-offs with growth rate or fecundity, our
results highlight the key role of development rate – differentiation of
the somatic cells per unit of time – in the evolution of life span. Since
development time is under strong selection in nature, reduced somatic
maintenance resulting in shorter life span may be a widespread cost of
rapid development.

生活史理论预测早期生活适合度与寿命之间存在权衡。传统上研究焦点多集中于繁殖力与寿命的权衡，但有充分理由推测生长速率和/或发育时间也可能存在此类权衡。我们通过在异交线虫Caenorhabditis remanei中开展两项独立选择实验，探究了生长速率和发育时间在寿命进化中的作用。首先，我们发现热休克选择下，线虫寿命延长且无繁殖力代价，但需以发育减缓为代价。随后，在第二项实验中，我们通过直接选择快发育或慢发育线虫，独立评估了发育时间、生长速率、繁殖力、热休克抗性与寿命之间的推定进化关联。该实验验证了我们的初步发现：选择慢发育线虫会使其寿命延长且热休克抗性增强。由于未观察到生长速率或繁殖力与寿命之间存在一致的权衡关系，我们的结果凸显了发育速率——即单位时间内体细胞的分化速率——在寿命进化中的关键作用。鉴于自然界中发育时间受到强烈选择，体细胞维持能力下降导致寿命缩短可能是快速发育的普遍代价。