Functional traits but not environmental gradients explain seed weight in Mongolian plant species

Seed weight varies by several orders of magnitude among vascular plant species. However, the importance of potential drivers such as environmental conditions and plant functional traits have rarely been assessed for a larger taxonomic sample. We collected seeds of 148 species from 237 sites spread across Mongolia and compared their weight among the major zonal vegetation types, taxonomic groups and a set of functional traits (growth form, dispersal mode, fruit type, storage organs and palatability). Seed weight strongly varied among all functional traits and taxonomic groups, but no differences among vegetation zones were detected. These results suggest a low impact of environmental conditions on the evolution of seed weight, contrasting the strong phylogenetic signal.