Data from: Should we sync? Seascape-level genetic and ecological factors determine seagrass flowering patterns

Spatial and temporal heterogeneity in flowering occur in many plant species with abiotic pollination and may confer fitness advantages through mechanisms such as predator satiation or pollination efficiency. Environmental factors such as light quality or quantity and temperature play an important role in inducing synchronisation on wide geographic scales. On a smaller geographic scale, external factors such as resource availability and herbivory are theorised to trigger flowering, while genetic factors may also play an important role. In this study, we assessed the importance of ecological and genetic factors in shaping seascape-level spatial heterogeneity in flowering of the seagrass Posidonia oceanica. By investigating spatially close sites (<20 km) with similar seascape configurations and depth, we assume that major environmental drivers (temperature and light) were equivalent. We assessed four ecological factors (productivity, leaf nitrogen and carbon content and herbivory) and three genetic factors (heterozygosity, relatedness and clonality) to assess three hypotheses for synchronised flowering in P. oceanica: (1) clone synchronisation (internal clock hypothesis), (2) variation in nutrient availability, potentially caused by spatial heterogeneity in herbivory rates or nutrient translocation via clonal integration (resource budget hypothesis) or (3) kin selection and sibling synchronisation. Internal relatedness and heterozygosity had a significant positive effect on the abundance of flowers. Moreover, productivity and genotypic richness (clonality) were negatively associated with flower density, although at a lower level of significance. In addition we found that clones were almost exclusively shared among mass-flowering patches and patches without mass-flowering, respectively. Synthesis. The results shed new light on seagrass flowering patterns and on the mechanisms of flower synchronisation at the patch level within a wider spatial scale. We found support for the kin selection hypothesis and indirect evidence for the resource budget hypothesis. Thus a combination of mainly genetic but also ecological factors causes the observed heterogeneous flowering patterns in Posidonia oceanica seascapes. In addition, we found a strong positive relationship between the number of flowers and heterozygosity, adding evidence to the controversial association between heterozygosity and fitness when a limited number of loci are used. To our knowledge, this study is the first to link both ecological and genetic factors with flower abundance in a species with a presumed masting strategy.

许多依靠非生物传粉（abiotic pollination）的植物类群均存在开花的时空异质性，该特性可通过捕食者饱和效应（predator satiation）或提升传粉效率等途径赋予种群适合度优势。在大地理尺度上，光照质与量、温度等环境因子在诱导开花同步性方面发挥关键调控作用。而在较小地理尺度下，资源可获得性、植食作用（herbivory）等外部因子被认为可触发开花，遗传因子同样可能发挥重要作用。

本研究旨在明确生态与遗传因子在塑造波西多尼亚海草（Posidonia oceanica）海洋景观尺度开花空间异质性中的重要性。通过调研空间距离相近（<20千米）、海草床景观构型与水深均相似的样地，本研究假设主要环境驱动因子（温度与光照）的作用效果趋于一致。本研究测定了四类生态因子（生产力、叶片氮碳含量与植食压力）与三类遗传因子（杂合性（heterozygosity）、亲缘关系（relatedness）与克隆性（clonality）），以此验证波西多尼亚海草开花同步性的三类假说：（1）克隆同步性假说（内部生物钟假说）；（2）养分可获得性变异假说——该变异可能由植食速率的空间异质性或通过克隆整合进行的养分转运所引发（资源预算假说）；（3）亲缘选择与同胞同步性假说。

分析结果显示，亲缘关系与杂合性对开花数量存在显著正向影响。此外，生产力与基因型丰富度（即克隆性）与开花密度呈负相关关系，但该关联的显著性水平较低。我们还发现，克隆株系几乎仅分别共享于盛开花斑块与无花斑块的内部，两类斑块间几乎不存在共享的克隆株系。

结论：本研究结果为海草开花模式以及更大空间尺度下斑块级开花同步性的调控机制提供了全新的认知视角。本研究验证了亲缘选择假说，并为资源预算假说提供了间接证据。由此可见，遗传因子与生态因子的共同作用造就了波西多尼亚海草海洋景观中观测到的开花异质性分布模式。

此外，本研究发现开花数量与杂合性之间存在显著的正相关关系，这为'当使用有限数量的基因座时，杂合性与适合度之间存在争议性关联'的观点补充了新的实证依据。据我们所知，本研究首次针对具有疑似同步开花结实策略（masting strategy）的物种，将生态与遗传因子与开花数量关联起来。