Geographic patterns and environmental correlates of taxonomic and phylogenetic diversity of aquatic plants in China

Abstract

Studies on large‐scale geographic patterns of aquatic plant diversity can promote research on the generality of macroecological patterns in different ecosystems. Here, we compiled a checklist of 889 aquatic angiosperms in China, including 738 helophytes (emergent and marshy plants) and 151 hydrophytes (submerged, free‐floating, and floating‐leaved plants). We explore the geographic patterns and environmental correlates of aquatic plant diversity based on six metrics including species richness (SR), weighted endemism (WE), phylogenetic diversity (PD), phylogenetic endemism (PE), the standardized effect size of phylogenetic diversity (PDses), and the standardized effect size of mean phylogenetic distance (MPDses). Our results show that the diversity of aquatic plants in China is extremely uneven, with high diversity in southeastern China and low diversity in northwestern China, and the geographic patterns of taxonomic and PD are generally consistent. The pattern of helophytes differs from that of hydrophytes. Notably, the wavy‐shaped pattern of aquatic plant diversity (especially SR and PD for hydrophytes) across the latitude observed in this study is not consistent with those previously observed for aquatic plants in other continents. Climatic variables and water environmental variables are the main drivers of aquatic plant diversity in China; however, the effects of individual variables differ between helophytes and hydrophytes. Water environmental variables have a greater impact on PDses and MPDses of hydrophytes than those of helophytes. Overall, our work provides insight into understanding the large‐scale patterns of aquatic plant diversity and is a critical addition to previous studies on the macroecological pattern of terrestrial organisms.

Large-scale geographic patterns and environmental and anthropogenic drivers of wetland plant diversity in the Qinghai-Tibet Plateau

“…Based on the checklist of endemic seed plant species in the QTP reported by Yu et al [58], we selected from the checklist of wetland plants in the QTP, resulting in a total of 395 endemic wetland plants in the QTP. Weighted endemism of wetland plants was calculated for each grid cell, using an arbitrary region or range size threshold to define what constitutes a species [59,60]. Phylogenetic endemism is the total phylogenetic branch length encompassed by wetland plant species in the QTP, where the phylogeny is modified so that each branch length is divided by the global range size of its descendant clade [61].…”