LOCAL POPULATIONS WITH HIGH CONSERVATION PRIORITY
Based on the phenotypes and haplotypes of C. incana revealed in previous study and the current status of its environment, we discuss the endangered local populations and their range listed in the Ministry of the Environment’s Red List Category, which is considered to be of high conservation priority [7].
First, populations in Tsushima were classified into two groups when compared with the whole of western Kyushu and five groups when compared with the inside of Tsushima based on the phenotype, and there were no relation with their geographical distributions.
On the other hand, the haplotypes were classified into three groups, and there were trends in their geographical distribution, but no association with phenotypic groups.
Therefore, it is difficult to define a large range of local populations taking into account both phenotypic and haplotype characteristics.
As for the present conditions, the disappearance of the natural population and the decrease in the population were confirmed for 7 years from 2007 to 2014, but the large population with numbers of individuals tended to be many in Tsushima than in other areas [8].
These results suggest that the risk of extinction in Tsushima is lower than that in other areas, and that there were no phenotypic or haplotype groups composed only of endangered populations, suggesting that conservation is not very urgent.
Subsequently, in Nagasaki mainland, the natural populations distributed in Hirado-jima and surrounding areas in the northwest showed a common phenotypic group, but different haplotypes were found between the northern and southern populations of Hirado-jima.
Among the populations reported by Ito and Kawasato [6], many of those assumed to have disappeared were distributed in the Nagasaki mainland, confirming that they were recently affected by human activities.
On the other hand, number of individuals in the natural populations which distributed in the northwest tended to be larger than that of the southern population, and they were found in exposed rocky areas at high altitudes, which were considered to be less affected by human activities.
Therefore, the conservation areas in Nagasaki mainland were classified into three groups, the group with H7 in the southern part of Hirado-jima, the group with H 13 in the northern part of Hirado-jima and its surroundings, the population in the central coastal area (C83), and the group with H 8 ~ H10 in the southern part.
In particular, number of individuals the southern group tended to be low, suggesting a high conservation priority.
In the Goto Islands, 4 populations out of 5 populations distributed in southern Fukue Island and its northeastern part, Kuga Island, were considered to be populations with high conservation priority, because number of individuals in their populations was less than 20, and especially, C 88 and C 102 distributed in the western and southern parts of Fukue Island showed haplotypes close to the ancestral population established early in the Goto Islands and were classified into different phenotypic groups.
No phenotypic or haplotype groups composed only of small populations with less than 20 individuals were found in the central part, Narushima and its northeast part, Nakatsushima Island, suggesting that conservation is not very urgent.
In the Koshikijima Islands, there are considered to be a high conservation priority area because they show characteristic phenotypes among the Japanese natural population.
In particular, populations distributed in Kamikoshikijima Island and Nakakoshikijima Island (C 103 to C 105) are considered to be conservation priority populations because of their small population size.
Haplotypes were also different between natural populations in Nagasaki mainland and the Goto Islands, which showed the same phenotypic group, suggesting that they should be conserved as separate local populations to maintain genetic diversity in all natural populations in Japan.
In addition, the low seed-dispersing ability of C. incana and its ecology as a lithophyte suggest that even within regions with the same haplotype, if phenotypic groups differ among populations, they should be preserved as finely divided as possible.
The delay in response of plant species to anthropogenic environmental changes suggests that the potential extinction crisis is more advanced than the present natural state [9,10]
These results of this study suggest that local populations and their ranges of high conservation priority should be set not only among regions but also within regions, and prompt actions should be taken.