Oksanen T A, Jonsson P, Koskela E, Mappes T
Department of Biological and Environmental Science, University of Jyväskylä, Finland.
Proc Biol Sci. 2001 Mar 22;268(1467):661-6. doi: 10.1098/rspb.2000.1409.
The number of offspring attaining reproductive age is an important measure of an individual's fitness. However, reproductive success is generally constrained by a trade-off between offspring number and quality. We conducted a factorial experiment in order to study the effects of an artificial enlargement of offspring number and size on the reproductive success of female bank voles (Clethrionomys glareolus). We also studied the effects of the manipulations on growth, survival and reproductive success of the offspring. Potentially confounding effects of varying maternal quality were avoided by cross-fostering. Our results showed that the number of offspring alive in the next breeding season was higher in offspring number manipulation groups, despite their smaller body size at weaning. Offspring size manipulation had no effect on offspring growth or survival. Further, the first litter size of female offspring did not differ between treatments. In conclusion, females may be able to increase the number of offspring reaching reproductive age by producing larger litters, whereas increasing offspring size benefits neither the mother nor the offspring.
达到生殖年龄的后代数量是衡量个体适合度的一项重要指标。然而，繁殖成功率通常受到后代数量与质量之间权衡的限制。我们进行了一项析因实验，以研究人为增加后代数量和大小对雌性棕背䶄（Clethrionomys glareolus）繁殖成功率的影响。我们还研究了这些操作对后代生长、存活和繁殖成功率的影响。通过交叉寄养避免了母体质量变化可能产生的混杂效应。我们的结果表明，尽管后代数量操纵组的后代在断奶时体型较小，但在下一个繁殖季节存活的后代数量更多。后代大小操纵对后代生长或存活没有影响。此外，不同处理组雌性后代的第一窝产仔数没有差异。总之，雌性可能能够通过产更多的仔来增加达到生殖年龄的后代数量，而增加后代大小对母体和后代均无益处。
