Phylogeography of Juniperus Species (Cupressaceae) with a Disjunct Distribution in the Island Areas of Japan

概要

Poster
Poster 5

Phylogeography of Juniperus Species (Cupressaceae)
with a Disjunct Distribution in the Island Areas of Japan
Hiroya TAGUCHI1, Daiki TAKAHASHI1, Takuro ITO2, Shuichiro TAGANE3,
Ryota SUGAWARA4,5, Emiko OGURI5, Harue ABE6 and Yoshihisa SUYAMA1
1

Grad. Sch. Agr. Sci., Tohoku Univ.
2
Bot. Gardens., Tohoku Univ.
3
Kagoshima Univ. Museum
4
Tokyo Metropolitan Univ.
5
Tokyo Gakugei Univ.
6
Sado Isl. Ctr. Ecol. Sustainabil., Niigata Univ.

A coastal conifer, Juniperus taxifolia var. lutchuensis (Cupressaceae) is distributed in the Ryukyu Islands, Izu Islands, and a part of
the Izu peninsula. This species is treated as a variety of J. taxifolia var. taxifolia which is endemic to the Bonin (Ogasawara) Islands.
Since these three Island groups are separated by more than 1,000 km away, it is interesting where this species originated and how it
expanded its distribution. On the other hand, J. conferta is distributed in Hokkaido, Honshu, and Kyushu Islands. This species grows
in a coastal environment like J. taxifolia var. lutchuensis and the two taxa are distinguished by the traits of their leaves. In areas where
distributions of these two species overlap, morphologically intermediate individuals have been reported; however, their phylogenetic
relationships are unclear.
In this study, we collected 267 samples of 7 Juniperus species including 27 populations of J. taxifolia and J. conferta from Japan
and Taiwan Island in order to reveal the phylogeographic relationship among these three taxa. We extracted DNA from leaves by the
CTAB method and obtained genome-wide SNPs by the MIG-seq analysis. Based on MIG-seq data, we conducted phylogenetic and
population genetic analyses.
The result of the phylogenetic analysis indicated that J. taxifolia var. lutchuensis didn’t form a monophyletic clade with var.
taxifolia but with J. conferta. Moreover, J. taxifolia var. taxifolia was monophyletic with J. formosana which is endemic to Taiwan
Island and southeast of mainland China. The results of the population genetic analyses indicated that J. taxifolia var. lutchuensis from
Izu Islands is genetically different from the Ryukyu Islands population and is closely related to J. conferta from Honshu Island. These
results suggest that J. taxifolia var. taxifolia originated from Taiwan or mainland China and that J. taxifolia var. lutchuensis has the
same origin as J. conferta with some genetic differentiation by expanding its distribution along the coast.

Photo. Juniperus taxifolia var. ...

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