Asymmetric contributions of seed and pollen to gene dispersal in the marsh orchid Dactylorhiza umbrosa in Asia Minor

Orchids differ from other plants in their extremely small and partly air-filled seeds that can be transported long distances by wind. Seed dispersal in orchids is expected to contribute strongly to overall gene flow, and orchids generally express low levels of genetic differentiation between populations and low pollen to seed flow ratios. However, studies in orchids distributed in northern Europe have often found a poor geographic structuring of genetic variation. Here, we studied geographic differentiation in the marsh orchid Dactylorhiza umbrosa, which is widely distributed in upland regions from Asia Minor to Central Asia. These areas were less affected by Pleistocene ice ages than northern Europe and the orchid should have been able to survive the last ice age in local refugia. In the plastid genome, which is dispersed by seeds, populations at close distance were clearly divergent, but the differentiation still increased with geographic distance, and a significant phylogeographic st...

兰科植物与其他植物的核心差异在于其种子体型极小且部分内部充有空气，可借助风力实现长距离传播。兰花的种子传播被认为对整体基因流具有显著贡献，且兰花种群间普遍呈现较低水平的遗传分化，同时花粉流与种子流的比值偏低。然而，针对北欧分布兰花的相关研究往往发现，其遗传变异的地理结构并不显著。本研究以沼生红门兰（Dactylorhiza umbrosa）为对象，探究其地理分化模式；该物种广泛分布于从小亚细亚至中亚的山地高原区域。相较于北欧，这些区域受更新世冰期的影响更小，该兰花可在当地冰期避难所中顺利度过末次冰期。在由种子传播的质体基因组（plastid genome）层面，近距离种群间已呈现出明显的遗传分化，但分化程度仍随地理距离增加而升高，且存在显著的系统地理学（phylogeographic）……