Allozyme Variation in Six Flowering Plant Species Characterizing Ullung Island, Korea

7 Pages·1998·0.44 MB·English

by  Hye Gi Chung

植物研究雑誌
J. Jpn. Bot.
Originals 73: 241-247 (1998)
Allozyme Variation in Six Flowering Plant Species
，
Characterizing Ullung IslandKorea
Hye Gi CHUNG，Ja e l\lin CHUNG and Myong Gi CHUNG
Department ofBiology，G yeongsang National University，Ch i吋u，660-701 KOREA
(Received on February 18，1 998)
A preliminyallozyme study on six populations of Fagus multinervis (endemic to
訂
the Ullung Island)，Pi nus parviflora，He patica maxima (endmic to the Island)，Ca mpanula
takesimana (endemic to the Island)，T im・ellapolyphylla，a nd Thymus quinquecostatus
var. japonicus on the Ullung Island from Korea was made. Populations of F. multinervis
and P. parviflora maintain moderate levels of allozyme variation (mean expected
heterozygosity ofO.253 in F. multinervis and 0.149 in P. parviflora)，wh ereas those of H.
maxima (0.032)，仁 takesimana(0.021)，T. polyphylla (0.016)，a nd T. quinquecostatus
var.japonicus (0.066) maintain low levels of allozyme diversity within populations. For
the latter four taxa，fa ctors such as founder effect，g enetic drift associated with small
population size，an d probable inbreeding contributed to their situation.
2
The Ullung Island，7 5.4 kmarea，is 10- (Yim 1993).
catedat 1300Ea nd 370N，ca .141 kmeastofthe Estimates of levels and distribution of ge-
Korean Peninsula. The Island had been formed netic diversity within and among rare 'and
by volcanic activities from the late Tertiary to endangered species could be useful to provide
the Quaternary. The flora on the Island has ab asis on which to build sound programs for
been ofbotanical interest because several sub- the conservation of genetic diversity of these
tropical plants grow on the Island owing to a plants (Soule 1986). In addition，ge netic diver-
warm current，th ough the Island is located in sity routinely from allozyme markers can be
the northern temperate region. About 500 vas- used as ay ardstick to measure the effective
同
cular plants grow on the Island (Oh 1978)，an d ness of in situ and ex situ conservation pro-
among them ca. 40 species are endemics. Re- grams (Hamrick et al. 1991). Despite the im-
cently，th e number ofvisitors to the Island has portance of knowl edge concerning genetic
been rapidly increased (several thousands in var、iation for providing information for con-
summer season) because several express pas- serrationpurposes，li ttle is known of the ge-
senger boats are available. In addition，se veral netic variation in plants native to the Island.
roads on hillsides have been recently enlarged Island plantpopulations generally harborfewer
and newly constructed. These activities could polymorphic loci and fewer alleles per locus
severel ya ffect the flora and natural habi tats on than mainland populations because they are
the Island. For these reasons，th e Korean gov- probably descended from one or af ew found-
ernment has designated six sites of natural ers (Hamrick et al. 1979).
forests as Na tural Monuments to protect rare As ap art of studies to preserve plant diver-
and endemic plants from human disturbances sity on the Island，th e objective ofthis prelimi-
241-
一
242 植物研究雑誌第73巻第5号 平成10年10月
nary study is to explore patterns of genetic subshrub，g rows on limestone and andesite
variations in six plant taxa on the Island. Fa gus regions in Japan (Hokkaido，H onshu and
multinervis Na kai (Fagaceae)，an endemic plant Kyushu)，th e northern China，M ongolia，a nd
to the Island，is an element of cool-temperate China (Kitamura and Murata 1986). Only one
forests in East Asia. It is al arge，lo ng-lived， population (3，226 m2) at the Nari Basin is
monoecious tree，a nd its wind-bome pollen known on the Ullung Island and has been
and potentially animal-dispersed seeds may designated as the Na tural Monument in Korea
allow fairly long-distance gene dispersal on and is now surrounded by aw ire fence because
the Island. Pinus parviflora Siebold & Zucc. of its rarity in South Korea. Flowering indi-
(Pinaceae) is distributed in Jap an (westem viduals of T. quinquecostatus var. japonicus
Honshu，S hikoku and Kyushu) and Ullung are visited by bees (M. Chung pers. obsよ
Island. Pinus parviflora is also ac omponent of
cool-temperate forests in the region. On the Materials and Methods
Ullung Island，o nly af ew natural stands in A total of 300 leaf samples was randomly
田
cluding one Na tural Monument stand are collected from six populations of the six taxa
known (Ahn 1971)，a nd the number of indi- on the Ullung Island. Mature leaves (or nee-
viduals in each stand are less than hundreds dles) were collected from 50 individuals per
(M. Chung pers. obs.). Like other conifers， population. For Fagus multinervis and Pinus
Pinus parviflora is al arge，lo ng-lived，w ind- parviflora，in dividuals (30-60 years old) were
pollinated monoecious tree. The seeds are collected from area covered ca. 5，000 m2.L eaf
1.5 cm long，0. 8 cm wide with 4m mw ing samples of Hepatica maxima，C ampanula
(Ahn 1971). Hepatica maxima Nakai takesimana，an d Tiarella polyphylla were col-
(Ranunculaceae)，a h erbaceous perennial，is lected from areas covered ca. 500 m2.L eaf
endemic to the Island. White flowers (1.5 cm samples，w rapped with aw et paper towel，
wide) are visited by bees (Chung pers. obs.). placed in plastic bags and stored on ice during
The achene is 5m mlo ng. Local populations of transport from the Island to the laboratory.
H.mαxima are found in patches，an d isolated Samples were then stored at 40Cu ntil proteins
from each other under hillside forests on the were extracted.
Island. Campαnula takesimana Na kai Leaf samples were cut finely and crushed
(Campanulaceae)，a n endemic of the Island， with am ortar and pestle. Ap hosphate-polyvi
国
grows on the forest margin near coastal areas. nylpyolidoneextraction buffer (Mitton et al.
町
Whitish pu中leflowers (3-5 cm long) are 1979) was added to leaf samples to facilitate
visited by bees and each capsule contains crushing and to aid enzyme stabilization. En-
hundreds of seeds. In Korea，T iarella zyme extracts were absorbed onto 4x6 mm
polyphylla D.Don (Saxifragaceae) only oc- wicks cut from Whatman 3m mc hromatogra-
curs under oak forests near the summit of the phy paper，w hich were stored at -70oCu ntil
Ullung Island，bu t the species widely distrib- needed. Electrophoresis was performed using
utes inJapan (Hokkaido，Ho nshu and Shikoku)， 10.5% starch gels to resolve scorable loci for
Taiwan，C hina and Himalaya (Kitamura and 13 enzyme systems: acid phosphatase (ACP)，
Murata 1987). Small white flowers are visited triosephosphate isomerase (TPI) ，ph osphoglu-
by bees (M. Chung pers. obs.)，an d each cap- comutase (PGM)，fl uorescent esterase (FE) ，
sule contains several small seeds (1.2-1.4 mm peroxidase (PER) ，a lcohol dehydrogenase
long). Thymus quinquecostatus Celak. var. (ADH)，m enadione reductase (MNR)，
japonicus H.Hara (Lamiaceae)，a d eciduous phosphoglucoisomerase (PGI)，d iaphorase
October 1998 Journal of Japanese Botany Vol. 73 No. 5 243
(DIA) ，is ocitrate dehydrogenase (IDH)，rn alate dures for DIA followed the rnethod described
dehydrogenase (MDH)，6 -phosphogluconate by Cheliak and Pitel (1984). All other stain
dehydrogenase (PGD)，an d skirnate dehydro- recipes were identical to those described by
genase (SKDH). Buffer systerns and putative Soltis et al. (1983). Putative loci were desig-
loci are listed in Table 1. The staining proce- nated sequentially，w ith the rnost anodally
Table 1. List ofbuffer systerns and resolvable enzyrne loci. FM，Fa gus multinervis; PP，Pi nus
P卯α門川iμfllorα，
and TQ，T hymus quinquecostαtus v japonicus: M indicates ar nonornorphic locus，P
， 訂.
indicates ap olyrnorphic locus，X i ndicates that the locus was poorly resolved could not be
scored. For TQ，d iaphorase (DIA) and 6-phosphogluconate dehydrogenase (PGD) were
resolved on ar norpholine citrate buffer systern
Buffer systern Loci FM PP HM CT TP TQ
Acph-1 X P M M 乱4 P
Acph-2 M
Acph・3 M
Acph-4 P
Tpi-1 M M M M M M
Tpi-2 M M M M
Tpi・3 M M
Pgm-1 M p P X M M
Pgm-2 p P
Fe-1 P p M M M M
Fe-2 M
Per M M M M M 島f
A rnodification Adh-1 孔f M M M M 乱f
(Hauf1er 1985) Adh-2 M M
of Soltis et al. Adh-3 M
(1983) systern 6 Mnr・-1 p P M X P M
Mnr-2 p M M M
Mnr-3 M
Pgi-1 M M M M M M
Pgi・2 p P P M M M
Dia-1 M M P M M
Dia-2 M M M
Dia-3 M

Idh-1 P M M M M M
A rnodification Idh-2 M M M M
(Chung and Kang Mdh-1 恥f P M M M
1994) of Soltis Mdh-2 p M M M
etal. (1983) Mdh-3 M M
Systern 11 Pgd-1 p M M M M M
Pgd-2 p 乱4 M M

Ab(aがnttunfd日m6.u町nYRut-e.uhvdlノbaO剖Hvdk旬mmCパいch9 tvdT也、ψiBFらゐ30、)rl&・・もvst戸し SSkkddhh--12 xx 孔f 恥Mf X M
244 植物研究雑誌 第73巻 第5号 平成10年10月
migrating isozyme designated ‘1'，t he next 0.253) (Table 2)，t hough the species is only
‘2'，a nd so on. Likewise，al leles were desig- restricted to the Ullung Island. Av ery similar
nated sequentially with the most anodally mi- result was reported within 14 populations of F.
grating allele designated ‘a'. All isozymes crenata in the Hokkaido and Honshu regions
resolved by the methods，e xpressed pheno- of northeastern Jap an: mean percentage of
types that were consistent in subunit structure polymorphic loci，th e number of alleles per
and genetic interpretation with most isozyme locus，m ean effective number of alleles per
studies in plants，as documented by Weeden locus，a nd the expected heterozygosity were
and Wendel (1989). 58%，2 .62，1 .34，a nd 0.202，r espectively
Levels of allozyme variation within (Takahashi et al. 1994). When we compare
populations were estimated for individual levels of allozyme variation observed in F.
populations with ac omputer program devel- crenata with those of F. multinervis，it could
oped by M D. Loveless and A. Schnabel (pers. be said that populations of F. multinervis on
comm.): percent polymo叩hicloci (P)，a ver- the Ullung Island are not genetically
age number of alleles per locus (A)，ef fective depauperate.
number of alleles per locus (Ae)，o bserved Pinus parviflora at the Ullung Island popu-
heterozygosity (Ho) and expected heterozy- lation also maintains moderate levels of
= =
gosity (He). allozyme variation (P 33 %， A 1.48; Ae =
Wright' s(1 922) fixation indices (め were 1.30; andHe =0 .149) (Table 2)，co mparable to
calculated for each polymorphic locus and for mean values of gymnosperms，av eraging 53 %
each population to reveal significant devia- of P，1. 83 of A，1. 20 of Ae，a nd 0.151 of He
tions in genotype frequencies from expecta- (Hamrick et al. 1992). Like other conifers，
tions under Hardy-Weinberg (H-W) equilib- factors such as longevity and outcrossing-
rium (Li and Horvitz 1953). These indices wind pollination might contribute to harbor a
were tested for deviations from 0b y aχ2 moderate level of allozyme variation within a
statistic following Li and Horvitz (1953). population of P. parv伊ora.
Although 1ca lculated at each of one popu-
Results and Discussion lation of Fagus multinervis and Pinus
Fa gus multinervis maintains higher levels parviflora，in breeding coefficients showed that
of genetic variation within ap opulation (He = significant deficiencies of heterozygotes exist
Table 2. Summary of allozyme variation within populations of FM，F agus multinervis; PP，
Pinus parviflora; HM，He patica mαxima; CT，C ampanula takesimana; TP，Ti arella
polyphyllα; and TQ，T hymus quinquecostatus var. japonicus: NL( PL)，N umber of loci
scored (number of polymorphic loci); P，pe rcentage of polymorphic loci; A，m ean number
of alleles per locus; Ae，m ean effective number of alleles per locus; Ho，m ean observed
heterozygosity; and He，m ean expected heterozygosity
Taxon NL (PL) P A Ae Ho( SE) He (SE)
FM 14 (8) 57.14 1.93 1.57 0.211 (0.048) 0.253 (0.068)
PP 11 (7) 33.33 1.48 1.30 0.107 (0.036) 0.149 (0.050)
HM 23 (2) 8.70 1.08 1.05 0.021 (0.017) 0.032 (0.023)
2
CT 4 (1) 7.14 1.07 1.03 0.014 (0.004) 0.021 (0.021)
1
TP 25 (1) 4.00 1.04 1.03 0.011 (0.013) 0.016 (0.016)
TQ 18 (3) 16.67 1.17 1.11 0.044 (0.025) 0.066 (0.036)
October 1998 Journal of Japanese Botany Vo .173 No. 5 245
for two (Mnr-l，0. 736，P < 0 .001 and Pgd-l， stricted ecological distribution，g rowing only
0.446，P < 0 .01) ofthe eight loci，wi th am ean in deciduous and conifer forests on the Ullung
Fo f 0.168，an d five (Pgm-l ，0. 598，P < 0 .001; Island (Nevo et al. 1984). Although Tiarella
Pgm-2，0. 326，P < 0 .01; Fe，0. 507，P < 0 .001; polyphylla has ab roader distributional range
Pgι2，0.374，P < 0 .01; andMdh-l，0. 340，P < in East Asia，t he population on the Ullung
0.01) ofthe seven loci，wi th ameanFo fO.336. Island is allozymically depauperate. Only one
Although F. multinervis is monoecious，th e locus (Mnr-l) of 25 loci investigated was
significant heterozygote deficiencies at two polymorphic. Again，t he population of Thy-
loci indicate that consanguineous matings mus quinquecostatus var. japonicus on the
might occur within ap opulation. Wec ollected Ullung Island also reveals the paucity of
samples within a 100x50 m area，s everal allozymic variability，t hough this taxon also
patches might be included in the electrophoretic distributed in East Asia. Only three (Acph-l，
analysis. This may create aW ahlund effect Acph-4，an d Pgm-2) of 18 loci examined were
causing heterozygote deficiencies. Higher lev- polymorphic. A very similar result was ob-
els ofheterozygote deficiencies compared with served in Lactoris fernandeziana Phil.
most conifers were observed at one population (Lactoridaceae) on the Juan Fernandez Island.
of Pinus parviflora. This in part may be due to The species revealed no variation at 22 loci
logging activities during the past several hun- (Crawford et al. 1993). The authors suggested
dreds and as mall number of individuals per that factors such as founder effect，g enetic
extant stand (less than hundreds). drift associated with small population sizes，
Each of one population of Hepatica maxima and as elfing breeding system contributed to
and Campanula takesimana maintains low the lack of allozyme variation in Lactoris
levels of allozyme variation: Po f 8.7 % and fernandeziana. As Tiarella polyphylla and
7.1 %;Ao f 1.08 and 1.07;Ae of 1.05 and 1.03， Thymus quinquecostatus var.japonicus do not
andHeofO.032andO.021，respectively. These occur in mainland Korea，b ut grow in the
estimates were lower than those of the other Jap anese Archipelago and the Ullung Island
mainland Hepatica and Campanula species in had connected to the Jap anese Archipelago
Korea and Jap an. For example，K orean (Oh 1978)，it is highly probable that the pro-
populations of H. asiatica Na kai (four genitor populations of these two taxa had mi-
populations) and H. insularis Nakai (six grated from the northern Jap an into the Ullung
populations) revealed meanp ercentage of poly- Island during the IceA ge (the glacial “Wurm").
morphic loci (P) of 79 % and 54 ，% mean The population size of thse two taxa on the
number of alleles per locus (A) of 2.76 and Ullung Island (Chung pers. obs.) is small.
2.31，a nd mean expected heterozygosity (He) After the last IceA ge，th e remnants of these
ofO.248 and 0.212，re spectively (Kima ndLee two taxa have been isolated to the Island with
1994). Seventeen Japanese populations of little opportunity forreceiving propagules (e.g.，
Campanula punctatαLam. harbor moderate pollen and seeds) from the Japanese Archi-
，
levels of allozyme variation (He =0 .123 from pelago. Nos pecial seed dispersal mechanism
seven mainland populations and 0.088 from is known to these two taxa. In addition，th e two
ten populations of the Izu Islands) (lnoue and taxa on the Ullung Island grow only af ew
Kawahara 1990). The low levels in populations location (Tiarella polyphylla) and only one
of H. maxima and C. takesimana may be location (Thymus quinquecostαtus var.
attributable to relatively small，i solated japonicus)，i ndicating restricted ecological
populations，e ndemism to an island，a nd re distribution. These information and allozyme
回
246 植物研究雑誌第73巻第5号 平成10年10月
data suggest that founder effect，e specially 一一一ーヲLinhartY. B. and Mitton J. B. 1979. Relation-
ships between life history characteristics and
genetic drift，a nd probable inbreeding may be
electrophoretically detectable genetic variation in
responsible for the considerably low levels of
plants. Annu. Rev. Ecol. Syst. 10: 173-200.
allozyme variation within populations of these Haufler C. H. 1985. Enzyme variability and modes of
two taxa. For af uture study，it would be good evolution in Bommeria (Pteridaceae). Syst. Bot. 10:
to examine diversity in mainland populations 92-104.
Kim J. H. and Lee N. S. 1994. Allozyme variation in
of the non-endemic taxa (e.g.，T iarella
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24: 79-93 (in Korean).
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Hoikusha Publ. Co.，O saka.
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一一一一-and一一一一 1987.Colored Illustrations of
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鄭孝基，鄭載E民，鄭明基:酵素多型を用い
た韓国欝陵島産植物 6種の遺伝的多様性に関する
研究 ハマソウ，タケシマホタルブクロ)，韓国では穆陵
韓国欝陵島固有の 3種(タケシマブナ，オオス 島のみに産する2種(ヒメコマツ，ズダヤクシュ)，
October 1998 Journal of Japanese Botany Vo .l73 No. 5 247
および韓国内の産地が限られているイブキジャコ 度の比較的高い遺伝的多様度を有することがわ
ウソウの計6種の植物について，保全生態学的見 かったが，他の 4種では集団内の遺伝的多様度は
地から島内の集団の遺伝的多様性を酵素多型によ 低かった.後者の理由としては，創始者効果，個体
り調査した.その結果 タケシマブナとヒメコマ 群サイズが小さいことによる遺伝的浮動，内交配
ツでは他地域で報告されている同属の植物と同程 等が考えられる(慶尚大学校生物学科)