The Evolutionary Significance of Seed Germinability in an Alpine Meadow on The Eastern Qinghai-Tibet Plateau

Abstract

In this study, we created a database of 633 species collected from alpine meadows on the eastern Qinghai-Tibet Plateau, and considered the correlation of interspecific seed germinability variation with ecological, life-history, and phylogenetic background. We found that taxonomic membership accounted for the majority of the weighted germination index (WGI) variation (71%). The strong taxonomic effect suggests that WGI variation within taxonomic membership is constrained, and a large proportion of WGI variation is explained by life-history traits also correlated with taxonomic membership. The overlap does not negate the adaptive significance of the relationship between these life-history traits and germinability. In addition, the altitudes and habitats when considered first had no significant effect on seed germinability variation, but we found that there were significant interactions between altitudes (or habitats) and some phylogenetic groups. Although their interactions were all less than the main effects of phylogenetic groups, they could explain that the effect of phylogenetic constraint on seed germination was also impacted by environmental factors. Thus, we could not exclude the effect of longtime selection by environmental factors on seed germination, and we think interspecific seed germinability variation was affected by phylogenetic, life-history, and ecological factors together.