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.

种子大小是决定幼苗建成时可利用贮藏物质多寡的关键生活史性状。目前学界已广泛观测到的种子大小分布格局包括：荫生生境中大种子物种的占比更高，以及种子大小与植株体型呈正相关。本研究以中欧植物区系为研究对象，分析了以埃伦贝格指示值（Ellenberg indicator values）、植株高度、生活型（life form）等植物功能性状（plant functional traits）所表征的实际生态位维度（realized niche dimensions）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（phylogenetic relatedness）信息，本研究不仅可考量当代生态学因素，还能纳入植物物种的演化历史。种子质量的演化速率较为缓慢，最适合用以生境或生活型为变量、带有多个适应峰（adaptive peaks）的选择-惯性模型（selection-inertia models）来解释。当模型以生境或生活型为最优值变量时，落叶林、盐水生境与海岸生境中的种子质量最优值最高，生活型分类下的高位芽植物（phanerophytes）亦是如此。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，能更好地解释种子质量的分布格局。本研究不仅印证了荫蔽环境与大种子之间的常见关联，还发现大种子与干旱环境之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，影响种子大小生态学特征的不仅有植株体型与光竞争，还有一系列复杂因素；对物种生态位的精准划分，能够加深我们对种子大小演化的理解。