Botanical Studies (2007) 48: 97-116.
Corresponding author: E-mail: email@example.com.
Taiwan is situated at the junction of the Ryukyu and
the Luzon Arcs, and is separated from Fujian Province,
China by the 150 km wide Taiwan Strait (Figure 1). When
the overall flora of this region became explored in the
century, it became clear that the flora of Taiwan
mainly originated from continental China (Wilson, 1920;
Masamune, 1934; Kanehira, 1936; Li,
1958) and the elements from the Philippines were limited
and restricted to the very south (Merrill, 1926; Li and
Keng, 1950; Li, 1953); while the flora of the Ryukyus (up
to the Amami group) was considered as an extension of the
flora of Taiwan,
separated from the flora of Japan (Kyushu
Island and to the north) (Masamune, 1934; Sonohara et
al., 1952; Hosokawa, 1958). These earlier viewpoints on
the floristic affinities have been supported by later floristic
analyses (Liu and Teruya, 1980; Hsieh et al., 1994; Shen,
1997; Hsieh, 2002). A well accepted explanation based
on geological/geographical information is that the Taiwan
Strait is mostly only 60-80 m deep and served as a bridge
connecting continental China and Taiwan several times
during the Pleistocene glacial episodes, whereas the Bashi
Strait between Taiwan and Luzon Island is deeper than
2,000 m and these islands have never been connected
(Shen, 1996). Our comparison on the native genera of
the Ryukyus listed in the "Flora of the Ryukyus, South of
Amami Island" (Hatusima and Amano, 1994) also reveals
that 96% (650 out of 672) of its native genera are also
native to Taiwan.
Phylogeny and taxonomy of Eurya (Ternstroemiaceae)
from Taiwan, as inferred from ITS sequence data
Chi-Chih WU, Zhi-Fu HSU, and Chih-Hua TSOU*
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, R.O.C.
(Received May, 19 2006; Accepted August 24, 2006)
ABSTRACT. Eurya is the largest genus in the Ternstroemiaceae. The 13 Eurya species in Taiwan constitute
an important element in various habitats from low to high elevated forests in the island. In an attempt to
understand the interspecies relationships and geographical history of these 13 species, we sequenced 123
samples representing 32 Eurya species from Taiwan, the Ryukyus, continental China, and Southeast Asia
at the nuclear ITS region. Sixteen species of five other genera of Ternstroemiaceae were also incorporated.
Molecular phylogenetic trees show that the Eurya species studied form a monophyletic group, organized into
five clades with geographical correlations. All the 17 Eurya species from Taiwan and the Ryukyus studied,
except E. loquaiana, together constitute two coherent, but distantly related clades: one clade stands at a basal
and isolated position, with four out of its five species endemic to these two regions; they are probably Tertiary
elements of northern China or their direct descendants. The other clade is much more advanced and has strong
affinity to the Eurya in southeast China, which suggests that the members were probably originated from the
Quaternary flora of southeast China. Ecological partitioning is thought to be the major mechanism for the
speciation of four Taiwan-endemic species from E. chinensis.
Keywords: Eurya; ITS; Ternstroemiaceae; Phylogeny; Taiwan; The Ryukyus.
Figure 1. Map of SE Asia and E Asia.