Olga V. Nakonechnaya,

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POPULATION-GENETIC STRUCTURE OF A RARE PLANT
ARISTOLOCHIA CONTORTA BUNGE (ARISTOLOCHIACEAE)
Olga V. Nakonechnaya, Olga G. Koren, Alla B.
Kholina, Yuri N. Zhuravlev
Institute of Biology and Soil Science, FEB RAS,
Vladivostok
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Aristolochia contorta Bunge
A. contorta Bunge is a unique herbaceous liana of
the Russian Far East, where this plant is
represented by a few small fragmented and badly
exhausted populations in the southwest part of
the Primorsky Krai and in the Jewish Autonomous
Region only. In Russia, the species is listed in
the Red Book of the Primorsky Krai as a
vulnerable species. This plant is uncommon in
nature through its sensitivity to destructive
changes of habitats.
Primorsky Krai
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In addition, A. contorta is a valuable medicine
plant and its collection for a herbal remedy
contributes to reduction of its natural
populations. Now these populations need in
protection and restoring. It would be specially
important for the saving not only this species,
but also for the closely connected with A.
contorta relict butterfly Sericinus montela Gray,
for which this plant is the single feed source.
Sericinus montela Gray
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In this work we try to estimate genetic variation
and differentiation of the Russian populations of
A. contorta using allozyme markers. The
following tasks were formulated 1. To estimate
the main parameters of genetic variation for four
natural populations of A. contorta from Petrovka,
Sukhodol and Razdolnaya rivers basins in
Primorsky krai. 2. To estimate variation and
differentiation degree among the populations.
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Razdolnaya river
Petrovka river
Sukhodol river
Fig. 1. The map of Aristolochia contorta area in
Primorsky Krai
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Fig. 1. Schematic representation of
electrophoretic patterns of enzymes (EST, FE,
PGM, GPT, IDH, GPI, SKDH, ADH, LAP, AAT, 6-PGD,
ACP, ME, MDH) studied in Aristolochia contorta
liaves.
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Table 1. Polymorphism parameters in Aristolochia
contorta compared to corresponding mean
parameters for different plant groups
Plants PS AS ?O ?E GST (FST) References
Aristolochia contorta 21.74 1.35 0.09 (0.019) 0.09 (0.022) 0.1617 Our data
Rare 36.7 (4.9) 1.94 (0.208) 0.219 (0.022) 0.206 (0.040) (Gitzendanner, Soltis, 2000)
Endemic 42.5 (7.6) 1.82 (0.15) 0.263 (0.023) 0.078 (0.016) 0.248 (0.037) (Hamrick et al., 1992)
Note PS the per cent of polymorphic loci at
the species level AS the number of alleles per
locus at the species level ?O observed
heterozygosity at the species level ?E
expected heterozygosity at the species level GST
(FST) the parameter of subdivision. The values
of standard mistakes are written in brackets
In the populations of A. contorta the level of
polymorphism is lower than in average for rare
and endemic plants.
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Table 2. Parameters of genetic variation in
natural populations of Aristolochia contorta
Populations H? H? n? A P95, P99,
Romanovka 0.08 0.10 1.11 1.26 21.74 21.74
Bolshoi Kamen 0.08 0.06 1.06 1.22 13.04 17.39
Ussuriiskii region 0.12 0.10 1.11 1.30 21.74 21.74
Oktiabrskii region 0.09 0.11 1.12 1.35 21.74 21.74
The average 0.09 (0.019) 0.09 (0.022) 1.10 1.28 19.57 20.65
Parameters of genetic diversity in four
populations studied were different. The highest
level of the genetic variation was revealed in
the population of the Oktiabrskii region,
whereas the lowest one was found in the Bolshoi
Kamen population. This fact may be explained by
the most anthropogenic pressure on this
territory.
Bolshoi Kamen 0.08 0.06 1.06 1.22 13.04 17.39
Oktiabrskii region 0.09 0.11 1.12 1.35 21.74 21.74
HO observed heterozygosity, HE the expected
heterozygosity n? - the effective number of
alleles per locus, A the number of alleles per
locus P95, P99, , polymorphism at the 95 and
99 criterion
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Fig. 2. The distribution of allele frequencies
of three polymorphic loci in Aristolochia
contorta populations.
Test for heterogeneity among all loci ?2109.58
df15 ?lt0.01.
Aat-1 (claret red and orange sectors of circuses
correspond to allele frequencies 1 and 2),
6-Pgd-2 (green and yellow), Fe-1 (blue and
yellow), Fe-2 (dark blue, cyan and white), Lap
(orange, yellow, green and cyan).
Additionaly some differences in allele set of Lap
locus between all localities studied were found.
Differences in allele frequencies among
populations were statistically significant over
all loci.
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Table 3. F-statistics analysis of the
Aristolochia contorta populations
Nem1.29
Loci FIS FIT FST
Aat 0.1316 0.3501 0.2515
6-Pgd-2 0.0225 0.0990 0.0782
Lap -0.5940 -0.4835 0.0693
Fe-1 0.0520 0.2547 0.2139
Fe-2 0.5808 0.6658 0.2027
Whole species -0.0023 0.1599 0.1617
FIS, inbreeding coefficient of individual
respecting a population FIT, inbreeding
coefficient of individual respecting the whole
species FST, the indicator of differentiation of
populations.
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We estimated the genetic relationships among
populations by Nei distances. Low differentiation
of the localities evidences common gene pull
among all populations and recent time of its
separation. Populations isolation period,
calculated by the formula of molecular clock is
about 11.5 thousands years ago and corresponds to
the beginning of Holocene when significant
warming of climate occurred. We suppose that
population of the Oktiabrskii region, located on
the southwest part of the Primorsky Krai, which
avoided the glaciations in Quaternary period, was
a refugium for A. contorta. After climate warming
the species spread along Razdolnaya river and
some its feeders, forming new populations.
Obviously, environmental changing and possibly,
economic development of this territory contribute
to the weakening of the gene flow and increase of
the population differ.
DN0.0229
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The conclusion
Thus, this study showed a low level of genetic
diversity and high level of genetic
differentiation between Russian A. contorta
populations. The data supposed that all the
populations of A. contorta in Primorsky Krai have
common gene pool. Today genetic drift is
contributing the main input to the population
genetic structure of the A. contorta. The
enhancing of genetic drift is connected with
reduction of reproductive and effective
population sizes under increasing of
anthropogenic pressure.
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