Department of Structural and Functional Biology, University of Naples Federico II, complesso Universitario MSA, I-80126 Naples, Italy.
Am Nat. 2010 Jan;175(1):98-105. doi: 10.1086/648555.
The ultimate causes of evolution of highly specialized pollination systems are little understood. We investigated the relationship between specialization and pollination efficiency, defined as the proportion of pollinated flowers relative to those that experienced pollen removal, using orchids with different pollination strategies as a model system. Rewarding orchids showed the highest pollination efficiency. Sexually deceptive orchids had comparably high pollination efficiency, but food-deceptive orchids had significantly lower efficiency. Values for pollinator sharing (a measure of the degree of generalization in pollination systems) showed the reverse pattern, in that groups with high pollination efficiency had low values of pollinator sharing. Low pollinator sharing may thus be the basis for efficient pollination. Population genetic data indicated that both food- and sexually deceptive species have higher degrees of among-population gene flow than do rewarding orchids. Thus, the shift from food to sexual deception may be driven by selection for more efficient pollination, without compromising the high levels of gene flow that are characteristic of deceptive species.
高度特化的授粉系统进化的根本原因还不太清楚。我们以具有不同授粉策略的兰花为模型系统，研究了专业化与授粉效率（即相对于经历花粉去除的花朵而言，授粉花朵的比例）之间的关系。有回报的兰花表现出最高的授粉效率。性欺骗兰花具有相当高的授粉效率，但食欺骗兰花的效率显著较低。传粉者共享（衡量授粉系统概括程度的一个指标）的值呈现相反的模式，即授粉效率高的组具有低的传粉者共享值。因此，低的传粉者共享可能是高效授粉的基础。种群遗传数据表明，食欺骗和性欺骗物种的种群间基因流程度都高于有回报的兰花。因此，从食欺骗到性欺骗的转变可能是由更高效授粉的选择驱动的，而不会损害欺骗物种的高水平基因流。
