Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.
Botanischer Garten und Botanisches Museum Berlin (BGBM), Freie Universität Berlin, Berlin, Germany.
Sci Rep. 2024 May 18;14(1):11392. doi: 10.1038/s41598-024-62065-4.
Uniparental reproduction is advantageous when lack of mates limits outcrossing opportunities in plants. Baker's law predicts an enrichment of uniparental reproduction in habitats colonized via long-distance dispersal, such as volcanic islands. To test it, we analyzed reproductive traits at multiple hierarchical levels and compared seed-set after selfing and crossing experiments in both island and mainland populations of Limonium lobatum, a widespread species that Baker assumed to be self-incompatible because it had been described as pollen-stigma dimorphic, i.e., characterized by floral morphs differing in pollen-surface morphology and stigma-papillae shape that are typically self-incompatible. We discovered new types and combinations of pollen and stigma traits hitherto unknown in the literature on pollen-stigma dimorphism and a lack of correspondence between such combinations and pollen compatibility. Contrary to previous reports, we conclude that Limonium lobatum comprises both self-compatible and self-incompatible plants characterized by both known and previously undescribed combinations of reproductive traits. Most importantly, plants with novel combinations are overrepresented on islands, selfed seed-set is higher in islands than the mainland, and insular plants with novel pollen-stigma trait-combinations disproportionally contribute to uniparental reproduction on islands. Our results thus support Baker's law, connecting research on reproductive and island biology.
当缺乏配偶限制植物的异交机会时，单亲繁殖是有利的。贝克定律预测，在通过远距离扩散（如火山岛）殖民的栖息地中，单亲繁殖会增加。为了验证这一点，我们分析了 Limonium lobatum 的多个层次的繁殖特征，并比较了自交和杂交实验后的种子设置，Limonium lobatum 是一种广泛分布的物种，贝克假设它是自交不亲和的，因为它被描述为花粉柱头二态性，即具有花粉表面形态和柱头乳突形状不同的花型，通常是自交不亲和的。我们发现了以前文献中未知的花粉和柱头特征的新类型和组合，以及这些组合与花粉亲和性之间缺乏对应关系。与以前的报道相反，我们得出结论，Limonium lobatum 包括自交亲和和自交不亲和的植物，它们具有已知和以前未描述的繁殖特征组合。最重要的是，具有新组合的植物在岛屿上的比例过高，岛屿上的自交种子设置高于大陆，具有新花粉柱头特征组合的岛屿植物不成比例地促进了岛屿上的单亲繁殖。因此，我们的研究结果支持了贝克定律，将生殖和岛屿生物学的研究联系起来。
