Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies.However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China. We conducted a spatial phylogenetic analysis of the Chinese angiosperm flora at the generic level to identify centers of neo-and paleoendemism. Our results indicate that:(i) themajority of grid cells in China with significantly high phylogenetic endemism(PE) were located in the mountainous regions;(ii) four of the nine centers of endemism recognized, located in northern and western China, were recognized for the first time;(iii) arid and semiarid regions in Northwest China were commonly linked to significant PE, consistent with other spatial phylogenetic studies worldwide;and(iv) six highpriority conservation gaps were detected by overlaying the boundaries of China’s nature reserves on all significant PE cells. Overall, we conclude that the mountains of southern and northern China contain both paleo-endemics(ancient relictual lineages) and neo-endemics(recently diverged lineages). The areas we highlight as conservation priorities are important for broad-scale planning, especially in the context of evolutionary history preservation.

Origin and differentiation of endemism in the flora of China

The present paper analyzed 239 endemic genera in 67 families in the flora of seed plants in China.The results showed that there are five families containing more than ten endemic genera,namely,Gesneriaceae(27),which hereafter refers to the number of endemic genera in China,Composite(20),Labiatae(12),Cruciferae(11),and Umbelliferae(10),15 families with two endemic genera,and another 30 families with only one endemic genus.Four monotypic families(Ginkgoaceae,Davidiaceae,Eucommiaceae and Acanthochlamydaceae)are the most ancient,relict and characteristic in the flora of seed plants in China.Based on integrative data of systematics,fossil history,and morphological and molecular evidence of these genera,their origin,evolution and relationships were discussed.In gymnosperms,all endemic genera are relicts of the Arctic-Tertiary flora,having earlier evolutionary history,and can be traced back to the Cretaceous or to the Jurassic and even earlier.In angiosperms,the endemic genera are mostly relicts,and are represented in all lineages in the“Eight-Class System of Classification of Angiosperms”,and endemism can be found in almost every evolutionary stage of extant angiosperms.The relict genera once occupied huge areas in the northern hemisphere in the Tertiary or the late Cretaceous,while neo-endemism mostly originated in the late Tertiary.They came from Arctic-Tertiary,Paleo-tropical-Tertiary and Tethys-Tertiary florisitic elements,and the blend of the three elements with many genera of autochthonous origin.The endemism was formed when some dispersal routes such as the North Atlantic Land Bridge,and the Bering Bridge became discontinuous during the Tertiary,as well as the climate change and glaciations in the late Tertiary and the Quaternary.Therefore,the late Tertiary is the starting point of extant endemism of the flora in China.