Munch Stephan B, Conover David O
Marine Sciences Research Center, State University of New York at Stony Brook, Stony Brook, New York 11794-5000, USA.
Evolution. 2003 Sep;57(9):2119-27. doi: 10.1111/j.0014-3820.2003.tb00389.x.
Several recent studies have demonstrated that rapid growth early in life leads to decreased physiological performance. Nearly all involved experiments over short time periods (<1 day) to control for potentially confounding effects of size. This approach, however, neglects the benefits an individual accrues by growing. The net effect of growth can only be evaluated over a longer interval in which rapidly growing individuals are allowed the time required to attain the expected benefits of large size. We used two populations of Menidia menidia with disparate intrinsic growth rates to address this issue. We compared growth and survivorship among populations subject to predation in mesocosms under ambient light and temperature conditions for a period of up to 30 days to address two questions: Do the growth rates of fish in these populations respond differently to the presence of predators? Is the previously demonstrated survival cost of growth counterbalanced by the benefits of increased size? We found that growth was insensitive to predation risk: neither population appeared to modify growth rates in response to predation levels. Moreover, the fast-growing population suffered significantly higher mortality throughout the trials despite being 40% larger than the slow-growing population at the experiment's end. These results confirm that the costs of rapid growth extend over prolonged intervals and are not ameliorated merely by the attainment of large size.
最近的几项研究表明，生命早期的快速生长会导致生理性能下降。几乎所有相关实验都在短时间内（<1天）进行，以控制体型可能产生的混杂效应。然而，这种方法忽略了个体生长所带来的益处。生长的净效应只能在更长的时间间隔内进行评估，在此期间，快速生长的个体有足够的时间获得预期的大体型带来的益处。我们使用了两个具有不同内在生长率的梅氏食蚊鱼种群来解决这个问题。我们比较了在环境光照和温度条件下，在中型生态箱中遭受捕食的种群之间的生长和存活率，为期长达30天，以解决两个问题：这些种群中的鱼类生长率对捕食者的存在是否有不同的反应？先前证明的生长生存成本是否会被体型增大带来的益处所抵消？我们发现生长对捕食风险不敏感：两个种群似乎都没有根据捕食水平改变生长率。此外，在整个试验过程中，快速生长的种群死亡率显著更高，尽管在实验结束时比生长缓慢的种群大40%。这些结果证实，快速生长的成本会持续较长时间，并且不会仅仅因为达到大体型而得到改善。
