Universidad Rey Juan Carlos, Tulipán s/n, Móstoles, Madrid, Spain.
Oecologia. 2013 Sep;173(1):73-81. doi: 10.1007/s00442-013-2609-8. Epub 2013 Feb 13.
Large floral displays receive more pollinator visits but involve higher production and maintenance costs. This can result in indirect costs which may negatively affect functions like reproductive output. In this study, we explored the relationship between floral display and indirect costs in two pairs of coflowering sympatric Mediterranean Cistus of contrasting flower size. We hypothesized that: (1) corolla production entails direct costs in dry mass, N and P, (2) corollas entail significant indirect costs in terms of fruit set and seed production, (3) indirect costs increase with floral display, (4) indirect costs are greater in larger-flowered sympatric species, and (5) local climatic conditions influence indirect costs. We compared fruit set and seed production of petal-removed flowers and unmanipulated control flowers and evaluated the influence of mean flower number and mean flower size on relative fruit and seed gain of petal-removed and control flowers. Fruit set and seed production were significantly higher in petal-removed flowers in all the studied species. A positive relationship was found between relative fruit gain and mean individual flower size within species. In one pair of species, fruit gain was higher in the large-flowered species, as was the correlation between fruit gain and mean number of open flowers. In the other pair, the correlation between fruit gain and mean flower size was also higher in the large-flowered species. These results reveal that Mediterranean environments impose significant constraints on floral display, counteracting advantages of large flowers from the pollination point of view with increased indirect costs of such flowers.
大型花卉展示会吸引更多的传粉者访问，但涉及更高的生产成本和维护成本。这可能导致间接成本，从而对生殖产量等功能产生负面影响。在这项研究中，我们探索了两种具有对比花大小的共开花地中海石南属植物之间的花展示与间接成本之间的关系。我们假设：（1）花瓣生产需要在干质量、氮和磷方面付出直接成本，（2）花瓣会在果实结实和种子生产方面产生重大的间接成本，（3）间接成本随花展示而增加，（4）在较大花的共生物种中，间接成本更大，（5）当地的气候条件会影响间接成本。我们比较了花瓣去除花朵和未处理对照花朵的结实率和种子产量，并评估了平均花朵数量和平均花朵大小对花瓣去除和对照花朵的相对果实和种子增益的影响。在所有研究的物种中，去除花瓣的花朵的结实率和种子产量都明显更高。在物种内，相对果实增益与个体花的平均大小之间存在正相关关系。在一对物种中，大花种的果实增益更高，果实增益与开放花朵数量之间的相关性也更高。在另一对物种中，大花种的果实增益与平均花大小之间的相关性也更高。这些结果表明，地中海环境对花展示施加了重大限制，通过增加此类花的间接成本，抵消了从授粉角度来看大花的优势。
