Ricklefs Robert E, Cadena Carlos Daniel
Department of Biology, University of Missouri-St Louis, 8001 Natural Bridge Road, St Louis, MO 63121-4499, USA.
Ecol Lett. 2007 Oct;10(10):867-72. doi: 10.1111/j.1461-0248.2007.01085.x.
We examined the relationship between number of offspring produced to a certain age and subsequent longevity in captive zoo populations of 18 species of mammal and 12 species of bird. The age cut-offs in each analysis were set to include 50%, 75% and 90% of the offspring produced in each of the population samples. Only one of 68 regressions was significant, and its slope was positive. In addition, we examined the relationship between age at first reproduction up to a certain age and longevity after that age, generally 5 years (3-8), among 17 species of mammal and 12 species of bird. Only one of these regressions had a significantly positive slope, indicating that early reproduction rarely reduces lifespan. Overall, we found no evidence that producing offspring in a zoo environment influences the age at death. Thus, although trade-offs might apply in natural populations under resource limitation, neither pregnancy, growth of the foetus and lactation in mammals, nor egg production in birds, reduces lifespan in the absence of such stress. If genetically based or other intrinsic antagonistic pleiotropy underlies the evolution of senescence, it was not evident in our analyses.
我们研究了18种哺乳动物和12种鸟类的圈养动物园种群中，活到一定年龄所生育的后代数量与随后寿命之间的关系。每次分析中的年龄截止点设定为纳入每个种群样本中所生育后代的50%、75%和90%。68次回归分析中只有一次显著，且其斜率为正。此外，我们还研究了17种哺乳动物和12种鸟类中，到一定年龄时的首次繁殖年龄与此后（通常为5年，范围3 - 8年）的寿命之间的关系。这些回归分析中只有一次斜率显著为正，表明早期繁殖很少会缩短寿命。总体而言，我们没有发现证据表明在动物园环境中生育后代会影响死亡年龄。因此，尽管在资源有限的自然种群中可能存在权衡，但在没有此类压力的情况下，无论是哺乳动物的怀孕、胎儿生长和哺乳，还是鸟类的产卵，都不会缩短寿命。如果基于基因或其他内在拮抗多效性是衰老进化的基础，在我们的分析中并不明显。
