Global hotspots of endemicity, rarity and speciation of aquatic macrophytes

Abstract

Context Most aquatic macrophytes are ecozone-endemic species, and approximately two-thirds of them have rare occurrence at global scale. These small-range plants are seriously under-studied at macroecological scale, despite their marked vulnerability to extinction through habitat loss and climate change. Aims To identify global hotspots of endemism and rarity of aquatic macrophytes and examine the factors that resulted in speciation hotspots of macrophytes in some areas of the planet. Methods We analysed a database of 3499 macrophyte species to locate speciation hotspots and assess the biogeographic and environmental drivers that maintain ecozone-endemic, and globally rare species within their current limited global areas of occupancy. Key results Ecozone-endemic and globally rare macrophyte species hotspots across the planet showed similar occurrence patterns and drivers among ecozones. Ecozone environmental conditions, particularly harsh environments, influenced macrophyte phylogenetic diversity and structure. Most macrophyte species diversification is recent (<10 million years ago). A negative association with bird-mediated zoochory was seen for endemicity and rarity hotspots. Conclusions This study identified hotspots of endemicity and rarity, and potential cradle and museum speciation areas. Implications Our findings could inform global action to conserve the macrophyte diversity of wetlands, and other inland aquatic habitats, across the world.