Abstract: Diversity and membership of species in a biological community result from the interplay between evolutionary and ecological processes. Plant ecologists often rely on family-level phylogenies to address various issues of community assembly because phylogenies resolved at the species or genus level are generally not available. Here, we present an updated time-calibrated family-level phylogeny that includes all families of extant seed plants (i.e., angiosperms and gymnosperms) in the world, and use the phylogeny to show patterns of genus and species richness and life forms of all seed plant families in the world across the phylogeny. In addition, we use the phylogeny to examine whether life forms (woody vs. herbaceous) of seed plant families in the world are non-randomly distributed across the phylogeny. Our study shows that life forms exhibit significant phylogenetic signal across the phylogeny of seed plants.

Key words: angiosperm, community ecology, gymnosperm, life form, phylogenetic signal.