Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
Institute of Botany, Czech Academy of Sciences, Průhonice, Czech Republic.
Plant Biol (Stuttg). 2020 May;22(3):522-532. doi: 10.1111/plb.13099. Epub 2020 Mar 12.
Species with vast production of dust-like windborne seeds, such as orchids, should not be limited by seed dispersal. This paradigm, however, does not fit recent studies showing that many sites suitable for orchids are unoccupied and most seeds land close to their maternal plant. To explore this issue, we studied seed dispersal and gene flow of two forest orchid species, Epipactis atrorubens and Cephalanthera rubra, growing in a fragmented landscape of forested limestone hills in southwest Bohemia, Czech Republic. We used a combination of seed trapping and plant genotyping methods (microsatellite DNA markers) to quantify short- and long-distance dispersal, respectively. In addition, seed production of both species was estimated. We found that most seeds landed very close to maternal plants (95% of captured seeds were within 7.2 m) in both species, and dispersal distance was influenced by forest type in E. atrorubens. In addition, C. rubra showed clonal reproduction (20% of plants were of clonal origin) and very low fruiting success (only 1.6% of plants were fruiting) in comparison with E. atrorubens (25.7%). Gene flow was frequent up to 2 km in C. rubra and up to 125 km in E. atrorubens, and we detected a relatively high dispersal rate among regions in both species. Although both species occupy similar habitats and have similar seed dispersal abilities, C. rubra is notably rarer in the study area. Considerably low fruiting success in this species likely limits its gene flow to longer distances and designates it more sensitive to habitat loss and fragmentation.
产生大量粉状风传种子的物种，如兰花，不应受到种子传播的限制。然而，这一范式并不适用于最近的研究结果，这些研究表明，许多适合兰花生长的地点尚未被占据，而且大多数种子都降落在离母体植物较近的地方。为了探讨这个问题，我们研究了两种森林兰花物种，即暗紫红色的蝴蝶兰和红顶兰，它们生长在捷克共和国西南部森林石灰岩丘陵的破碎景观中。我们结合使用种子诱捕和植物基因型分析（微卫星 DNA 标记）来分别量化短距离和长距离的扩散。此外，我们还估计了这两个物种的种子产量。我们发现，在这两个物种中，大多数种子都降落在离母体植物非常近的地方（95%的捕获种子都在 7.2 米以内），并且在 E. atrorubens 中，扩散距离受到森林类型的影响。此外，与 E. atrorubens（25.7%）相比，C. rubra 表现出克隆繁殖（20%的植物是克隆起源）和极低的结实成功率（只有 1.6%的植物结实）。在 C. rubra 中，基因流在 2 公里以内很频繁，在 E. atrorubens 中可以达到 125 公里，并且在这两个物种中，我们都检测到了相对较高的区域间扩散率。尽管这两个物种占据相似的栖息地，并且具有相似的种子扩散能力，但 C. rubra 在研究区域中明显更为罕见。在这个物种中，相当低的结实成功率可能限制了其基因流的距离，并使其对栖息地的丧失和破碎更加敏感。
