Community-wide germination strategies in an alpine meadow on the eastern Qinghai-Tibet plateau: phylogenetic and life-history correlates

In this study, we built up a database of 633 species (48 families, 205 genera) from an alpine meadow on the eastern Qinghai-Tibet plateau. Our objective was to assess the effects of phylogenetic and life-history (life form, perenniality, seed size, dispersal strategy and period) background on the community-wide germination strategies. We found that the seeds of shrubs, perennials, and well-dispersed plants, and the smaller seeds germinated more and comparatively earlier. In one-way ANOVAs, phylogenetic groups explained 12% of the variance in GT (mean germination time for all seeds germinated of each species); life-history attributes, such as seed size, dispersal strategy, perenniality and life form explained 10%, 7%, 5%, and 1% respectively, and dispersal period had no significant effect on GT. Multifactorial ANOVAs revealed that the three major factors contributing to differences in GT were phylogenetic relatedness, seed size and dispersal strategy (explained 4%, 5% and 4% of the interspecific variation independently, respectively). Thus, seeds germination strategies were significantly correlated with phylogenetic and life-history relatedness. In addition, phylogenetic relatedness had close associations and interactions with seed size and dispersal strategy. Then, we think phylogeny and life-history attributes could not be considered mutual exclusively. Seed germination, like any other trait, is shaped by the natural history of the species and by the evolutionary history of the lineage. And a large percentage of the variance remained unexplained by our model, which suggested important selective factors or parameters may have been left out of this analysis.