Data from: Ecological niche and phylogeny explain distribution of seed mass in the Central European flora

Seed size is a crucial life-history trait determining the amount of reserves that are available to establishing seedlings. The most frequently observed patterns in seed size distribution are a higher frequency of large-seeded species in shaded habitats and a positive correlation of seed size with plant size. We analysed to what extent realised niche dimensions, as expressed by Ellenberg indicator values and plant functional traits such as plant height and life form, explained seed mass variation in the Central European flora. By including information on phylogenetic relatedness of the species, not only contemporary ecology but also the evolutionary history of plant species could be taken into account. Seed mass evolution was slow and was best explained by selection-inertia models with multiple adaptive peaks as a function of either habitat or life form. The highest seed mass optima were observed in the deciduous forest and saltwater and seashore habitats, and in phanerophytes in case of models with optima as a function of life form. The analyses showed that Ellenberg values were more important than habitat and life form in explaining seed mass distribution in the Central European flora. The often observed relation between shade and large seeds was also evident in our study, but we found an equally important relation between large seeds and drought and a positive relation between seed mass and salinity. Our results indicate that not only plant size and competition for light but a complex set of factors influence the ecology of seed size, and that a more precise delineation of species' niches improves the understanding of seed size evolution.

种子大小是决定定植幼苗可利用储藏物质总量的关键生活史性状。在种子大小分布格局中，最常被观测到的规律为：阴生生境中大种子物种的出现频率更高，且种子大小与植株体型呈正相关。本研究针对中欧植物区系，分析了以埃伦贝格指示值（Ellenberg indicator values）、植株高度与生活型等植物功能性状所表征的现实生态位维度，在多大程度上解释了种子质量的变异。通过纳入物种的系统发育亲缘关系信息，本研究不仅可考量当代生态因子，还能兼顾植物物种的演化历史。种子质量的演化进程较为缓慢，最适合用选择惯性模型（selection-inertia models）解释，该模型包含多个随生境或生活型变化的适应峰。当以生境或生活型为变量设置适应峰时，种子质量最优值最高的类群分别见于落叶林、盐水与滨海生境，以及高位芽植物（phanerophytes）类群。分析结果表明，在中欧植物区系中，埃伦贝格指示值相较于生境与生活型，对种子大小分布的解释力更强。本研究既验证了阴生与大种子的常见关联，也发现大种子与干旱胁迫间存在同等重要的关联，且种子质量与盐度呈正相关。本研究结果显示，影响种子大小生态格局的不仅有植株体型与光竞争，还包括一系列复杂因子；同时，对物种生态位的精准界定有助于深化对种子大小演化的认知。