Tempo-spatial evolution of seed plant endemism in Taiwan island

Aim: In Taiwan island, dispersal through recent land-bridge and
oversea after the appearance of proto-Taiwan (<6.5 Ma) is
responsible for its biodiversity assembly. While radiations have also been
widely reported in mountain systems. So, the tempo-spatial route to the
floral hotspot was determined through a meta-analysis of
evolution of endemic plants. Location: Taiwan island and adjacent
Asian regions. Taxon: Seed plants. Methods: Published
dated phylogenies were compiled, and the stem ages were considered as
origin times. Ancestral range shift pattern and/or
distribution of sister lineage/species were used to determine the
speciation mode, in situ origin or dispersal. The distributions
of sister taxa were assigned to ten different biogeographical regions.
Histograms quantifying the number of different origin mode events within
0.5 Ma bins were constructed. Possibility of long-distance dispersal
(LDD) was evaluated. Results: The 125 sampled endemic plants
originated between the late Eocene and late Pleistocene, with 111 species
(88.8%) originating after the emergence of proto-Taiwan and 14 species
(11.2%) before. Spatially, in situ speciation contributed more to the
formation of endemism than dispersal (56.8% vs 43.2%). The mean
ages of in situ origin species (1.83 Ma) are significantly
younger than that of dispersal (6.34 Ma). The main regions from
which dispersal occurred were south-central (n=29) and southeast China
(n=28) (referred to as south China), followed by Japan
(n=14). High ratio (60.8%) of LDD ability is found. Main
conclusions: Spatially, recent land-bridge and
oversea dispersal from the adjacent flora of Asia is supported and
southwest and southeast China are the most important sources. In
situ speciation that may be correlated with mountain
uplift, monsoon intensification and Pleistocene climatic fluctuations
exert greater contributions. Temporally, floral endemism is predominantly
origin after the emergence of proto-Taiwan. Additional investigations with
more sophisticated sampling and genetic data are needed in the future.