Large-scale patterns of biodiversity and the underlying mechanisms that
regulate these patterns are central topics in biogeography and
macroecology. The Qinghai-Tibetan Plateau (QTP) is a natural laboratory
for studying these issues. However, most previous studies have focused
on the entire QTP, and the independent physical geographical subunits in
the region are not well understood. We studied the current plant
diversity on the Kunlun Mountains, an independent physical geographical
subunit located in northwest China, on the northern edge of the QTP. We
integrated measures of species distribution, geological history, and
phylogeography, and analyzed the taxonomic richness, origin time, and
community phylogenetic structure of the plants present in the area. The
distribution patterns of 1,911 seed plants highlighted that species were
located mainly in the eastern regions of the Kunlun Mountains. Chinese
endemic species of seed plants accounted for 29.8% of the total species
on the Kunlun Mountains. The biodiversity patterns and mean divergence
times (MDT) indicated that the eastern region of the Kunlun Mountains
was the center for biodiversity conservation, particularly in the
southeastern region, which has served as a museum for plant diversity on
the Kunlun Mountains. According to the MDT, the origin time of the
Kunlun Mountains’ flora (KMF) was early Miocene (19.40 Ma), and the KMF
is ancient. The biogeographical roles of the Kunlun Mountains were
corridor and sink, and the corresponding key processes were species
immigration and extinction. The extant biodiversity on the Kunlun
Mountains has occurred through species recolonization after climatic
fluctuations and glaciations during the Quaternary. The Kunlun Mountains
also formed a barrier, representing a boundary among multiple floras,
and converted the QTP into a closed physical geographical unit. The
nearest taxon index indicated that habitat filtering may have played an
important role in biodiversity patterns.
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