NTNU, Museum of Natural History and Archaeology, Trondheim, Norway.
Oecologia. 2011 Oct;167(2):461-8. doi: 10.1007/s00442-011-2006-0. Epub 2011 May 10.
A cost of reproduction in terms of reduced future performance underlies all life-history models, yet costs have been difficult to detect in short-term experiments with long-lived plants. The likelihood of detecting costs should depend on the range of variation in reproductive effort that can be induced, and also on the shape of the cost function across this range, which should be affected by resource availability. Here, we experimentally examined the effects of both reduced and increased fruit production in two populations of the long-lived orchid Gymnadenia conopsea located at sites that differ in length of the growing season. Plants that were prevented from fruiting produced more flowers in the population with a longer growing season, had higher survival in the other population, and grew larger compared to control plants in both populations. Fruit production was pollen-limited in both populations, and increased reproductive investment after supplemental hand-pollination was associated with reduced fecundity the following year. The results demonstrate that the shape of the cost function varies among fitness components, and that costs can be differentially expressed in different populations. They are consistent with the hypothesis that differences in temporal overlap between allocation to reproduction and other functions will induce among-population variation in reproductive costs.
生殖成本是所有生活史模型的基础，即降低未来的表现，然而在对长寿植物进行的短期实验中，成本一直难以被发现。检测成本的可能性应该取决于可以诱导的生殖努力的变化范围，也取决于跨此范围的成本函数的形状，而这又应该受到资源可用性的影响。在这里，我们在两个位于生长季节长短不同的地点的长寿命兰花 Gymnadenia conopsea 种群中，实验性地检查了减少和增加果实产量的影响。在生长季节较长的种群中，阻止结实的植物会产生更多的花，在另一个种群中，植物的存活率更高，与两个种群中的对照植物相比，植物的生长也更大。在两个种群中，果实的产生都受到花粉的限制，在补充人工授粉后增加生殖投资，与第二年繁殖力降低有关。研究结果表明，成本函数的形状在不同的适应度成分之间存在差异，并且在不同的种群中可能会有不同的表现形式。这与假设一致，即生殖分配与其他功能之间的时间重叠差异将在种群之间诱导生殖成本的变化。
