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.