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.