COMPARISON OF PHENOTYPES AND CHLOROPLAST DNA HAPLOTYPES
We compared the phenotypically classified groups based on the results of
growth surveys with the previously reported phylogenetic analysis of
chloroplast DNA haplotypes [8].
First, in Tsushima, six types of haplotypes were distributed and
classified into three groups according to sequence variation.
Haplotypes revealed that H1 (Haplotype group 1), H2, and H3-H6 are
widely distributed in southern, eastern, and northern southern and
northern, respectively.
On the other hand, the phenotypes were classified into 2 groups by
growth survey in 20 populations on Tsushima out of 57 populations in
western Kyushu, and there was no tendency in the geographical
distribution of each group.
Therefore, since the association between haplotypes and phenotypic
groups in Tsushima was low and there were different phenotypic groups
among populations with common haplotypes, it was considered that each
natural population acquired various phenotypes by adapting to various
natural environments after colonizing in the southern and expanding its
distribution toward the northern.
Subsequently, nine haplotypes were distributed in the Goto Islands,
which revealed a relatively high level of genetic diversity [9].
Populations with H 12, H 16, and H 21 showed the phenotype of group C,
and groups of common phenotypes within populations showing common
haplotypes.
However, these haplotypes belonged to different subgroups within the
group of the Goto Islands in the phylogenetic tree and haplotype
network, suggesting a low correlation between the timing of distribution
formation and the phenotype.
These results suggest that in the Goto Islands, as in the Tsushima,
various phenotypes have been acquired through the progress of adaptive
differentiation to each natural environment after isolation to each
population.
On the other hand, the above populations showing common haplotypes were
classified into a group of common phenotypes, suggesting that similar
environmental factors might have caused differentiation into similar
phenotypes in these populations, and that populations showing the same
haplotypes that had been connected or had seed exchange until recently
might have been divided, showing the present geographical distribution.
In Nagasaki mainland, 6 haplotypes are distributed and classified into 3
groups based on sequence variation, with H7 to H 10 found in the
southern part of Hiradojima Island in the northwest and around Nagasaki
City in the southern part, H 13 in the northern part of Hiradojima
Island, Shiradake (C 82) and Matoyama-oshima (C 109), and H 22 in the
central part of Nagasaki mainland (C 83).
The population in the central part of Nagasaki mainland (C83) with H22
from the Goto Islands, showed the phenotype of group D common to the
population with H22 distributed in the Nakadori Islands of the Goto
Islands.
On the other hand, populations with H 13, which was considered to be
derived from Kyushu mainland and shared with the Koshikijima Islands,
and populations showing H7, which was considered to be an ancestral
haplotype that settled in this region after being separated from the
Goto Islands, tended to show the phenotype of group C.
These results suggest that geographical variations in the Nagasaki
mainland were caused by differences in natural environments between the
southern and northwestern parts of the island, rather than differences
in the timing of distribution formation with haplotypes, resulting in
different phenotypes in plant height and earliness of flowering.
In the Koshikijima Islands, 3 haplotypes were distributed, and it is
considered that ancestral populations with H 13, which is common to the
northwest of the Nagasaki mainland, expanded its distribution to
Shimokoshikijima after moving from the Kyushu mainland to
Kamikoshikijima.
In terms of phenotypes, the population in Kamikoshiki Island (C106)
showed the phenotype of group C distributed in the Goto Islands and the
Nagasaki mainland, and the other 4 populations showed the phenotype of
group E that were greatly different from those in other regions in terms
of floral organs and flower cluster sizes.
Since the former population is located along the road where slope
machining work was carried out, it was considered that the population
was formed by the planting brought in from Nagasaki mainland or the Goto
Islands.