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1.
RAPD analysis of genetic diversity and population genetic structure of Stipa krylovii reshov. in Inner Mongolia steppe 总被引:1,自引:0,他引:1
J. L. Wang N. X. Zhao Y. B. Gai F. Lin A. Z. Ren W. B. Ruan L. Chen 《Russian Journal of Genetics》2006,42(5):468-475
Random amplified polymorphic DNA (RAPD) analysis was used to characterize the genetic diversity and population genetic structure
of Stipa krylovii populations in Inner Mongolia steppe of North China. Thirteen 10-bp oligonucleotide primers, which generated 237 RAPD bands,
were used to analyze 90 plants of five populations from three regions, meadow steppe, typical steppe and desert steppe, from
the east to the west. The genetic diversity of Stipa krylovii that was revealed by observed number of alleles (na), expected number of alleles (ne), Nei’s diversity index (h), Shannon’s diversity index (H), amplificated loci, polymorphic loci and the percentage of polymorphic loci (PPB) increased from the east to the west. The Pearson’s correlation analysis between genetic diversity parameters and ecological
parameters indicated that the genetic diversity of Stipa krylovii was associated with precipitation and cumulative temperature variations along the longitude (humidity were calculated by
precipitation and cumulative temperature). Dendrogram based on Jaccard’s genetic distance showed that the individuals from
the same population formed a single subgroup. Although most variation (56.85%) was within populations, there was high genetic
differentiation among populations of Stipa krylovii, high differentiation within and between regions by AMOVA analysis. Either Nei’s unbiased genetic distance (G
ST) or gene flow (Nm) among pairwise populations was not correlated with geographical distance by Mantel’s test (P > 0.05), suggesting that there was no consistency with the isolation by distance model in these populations. Natural selection
may have played a role in affecting the genetic diversity and population structure, but habitat destruction and degradation
in northem grassland in China may be the main factor responsible for high genetic differentiation among populations, within
and among regions.
The text was submitted by the authors in English. 相似文献
2.
Sandra Joaquim Jorge Pereira Alexandra Leitão Domitília Matias Raquel Chaves Henrique Guedes-Pinto Luís Chícharo Miguel Gaspar 《Helgoland Marine Research》2010,64(4):289-295
The pullet carpet shell Venerupis senegalensis (=V. pullastra) is a commercially important species in Portugal, Spain, France, and Italy. In Portugal, this species was once abundant in
the Ria Formosa (southern Portugal). However, in the early 1980s, its abundance declined dramatically due to overfishing.
In order to reverse this negative trend, the genetic sustainable management of the wild stocks of V. senegalensis should be performed by promoting successful restocking actions and the development of an aquaculture commercial production
program of this species. In order to find the best broodstock for aquaculture purposes and therefore minimize the deleterious
effects of hatchery practices, we analyzed the genetic diversity of the natural population to be restocked (Ria Formosa) but
also of another potential genetically close population (Ria de Aveiro) by RAPD. Similar and substantive percentage of polymorphic
loci, effective number of alleles, Nei’s gene diversity, and Shannon’s diversity index was found within both populations. This
high genetic variability within populations suggests that they might have a gene pool with sufficient genetic plasticity to
support changes in the environmental conditions. Analyses of population genetic structure also revealed a small genetic differentiation
between the two populations. The high genetic variability of the natural population to be restocked makes it the preferential
broodstock for aquaculture purposes. However, the Ria de Aveiro population could also be a viable alternative, due to its
genetic plasticity and the genetic similarity of both populations. The results of this study can be useful to the sustainable
management of wild stocks as well as in promoting successful restocking actions based on aquaculture production. 相似文献
3.
Genetic variability in random amplified polymorphic DNA (RAPD) was studied in 90 individuals of Caragana microphylla, an outcrossing perennial shrub species, from five natural populations sampled in Inner Mongolia steppe of China on a small
scale. Nineteen selected primers were used to amplify DNA samples, and totally 225 bands were detected. The percentage of
polymorphic bands within populations ranged form 58.22% to 63.56%, with an average of 60% at the population level and 71.11%
at the species level, indicating relatively high genetic variations in C. microphylla species. Shannon’s information index (l) and Nei’s gene diversity (h) showed the similar trend with each other. According to the analysis of Nei’s gene diversity, the percentage of genetic variation
among populations was 7.13%, indicating a low level of genetic differentiation among populations. There existed a strong gene
flow (N
m
= 3.26) among populations. Although AMOVA analysis also revealed most variation was within populations (ΦST = 4.1%), a significant proportion was observed among populations (P < 0.001) in the present study, suggesting genetic differentiation occurred among populations at a certain extent. Based on
Mantel’s tests and the results of previous studies, the genetic structure pattern of C. microphylla accorded with the isolation-by-distance model on a very large scale, however, on a small scale, the significant genetic differentiation
among populations might be enhanced by the micro-environmental divergence among the sampling sites, rather than by geographic
factors. Analysis of the genetic variations of C. microphylla populations provided useful information for the adaptive strategy of Caragana species. 相似文献
4.
Tamarix chinensis, with its important ecological significance, is a vital dominant plant in the Yellow River Delta of China. To understand
its genetic structure and population dynamics, five populations of T. chinensis, consisting of 140 individuals, were analyzed in this study using inter simple sequence repeat markers. Seventy-eight polymerase
chain reaction fragments were scored, of which 62 were polymorphic. The mean percentage of polymorphic loci (P), the mean Nei’s gene diversity (h), and the mean Shannon’s information index (I) were 79.5%, 0.239, and 0.363, respectively. These indexes indicated that a moderate level of genetic diversity existed in
T. chinensis populations of the Yellow River Delta. Both analysis of molecular variance (AMOVA) (Φ
st = 0.169) and Popgene (G
st = 0.159) analyses revealed the low level of genetic differences among the five populations of T. chinensis. The results implied that relatively frequent gene flow existed among populations. However, slightly uneven genetic diversity
was also found among populations. Unweighted pair group method with arithmetic mean and principal component analysis showed
that populations with similar soil salinity had a close relationship, rather than populations with closer geographical distance.
A significant negative correlation between genetic diversity and soil salinity of the five populations (r = −0.958, p < 0.01) showed that soil salinity played an important role in shaping the population genetic structure of T. chinensis in the Yellow River Delta, China. 相似文献
5.
Xiao-Li Peng Chang-Ming Zhao Gui-Li Wu Jian-Quan Liu 《Trees - Structure and Function》2007,21(4):457-464
Repeated cycles of retreat and recolonization during the Quaternary ice ages are thought to have greatly influenced current
species distributions and their genetic diversity. It remains unclear how this climatic oscillation has affected the distribution
of genetic diversity between populations of wind-pollinated conifers in the Qinghai-Tibetan region. In this study, we investigated
the within-species genetic diversity and phylogenetic relationships of Picea likiangensis, a dominant forest species in this region using polymorphic DNA (RAPD) markers. Our results suggest that this species has
high overall genetic diversity, with 85.42% of loci being polymorphic and an average expected heterozygosity (H
E) of 0.239. However, there were relatively low levels of polymorphism at population levels and the differences between populations
were not significant, with percentages of polymorphic bands (PPB) ranging from 46.88 to 69.76%, Nei’s gene diversity (H
E) from 0.179 to 0.289 and Shannon’s indices (Hpop) from 0.267 to 0.421. In accordance with our proposed hypothesis, a high level of genetic differentiation among populations
was detected based on Nei’s genetic diversity (G
ST = 0.256) and AMOVA analysis (Phi
st = 0.236). Gene flow between populations was found to be limited (Nm = 1.4532) and far lower than reported for other conifer species with wide distribution ranges from other regions. No clusters
corresponding to three morphological varieties found in the south, north and west, respectively, were detected in either UPGMA
or PCO analyses. Our results suggest that this species may have had different refugia during the glacial stages in the southern
region and that the northern variety may have multiple origins from these different refugia. 相似文献
6.
Genetic variation of four populations of Sargassum thunbergii (Mert.) O. Kuntze and one outgroup of S. fusiforme (Harv.) Setchell from Shandong peninsula of China was studied with random amplified polymorphic DNA (RAPD) and inter-simple
sequence repeat (ISSR) markers. A total of 28 RAPD primers and 19 ISSR primers were amplified, showing 174 loci and 125 loci,
respectively. Calculation of genetic diversity with different indicators (P%, percentage of polymorphic loci; H, the expected heterozygosity; I, Shannon’s information index) revealed low or moderate levels of genetic variations within each S. thunbergii population. High genetic differentiations were determined with pairwise Nei’s unbiased genetic distance (D) and fixation index (F
ST
) between the populations. The Mantel test showed that two types of matrices of D and F
ST
were highly correlated, whether from RAPD or ISSR data, r = 0.9310 (P = 0.008) and 0.9313 (P = 0.009) respectively. Analysis of molecular variance (AMOVA) was used to apportion the variations between and within the
S. thunbergii populations. It indicated that the variations among populations were higher than those within populations, being 57.57% versus
42.43% by RAPD and 59.52% versus 40.08% by ISSR, respectively. Furthermore, the Mantel test suggested that the genetic differentiations
between the four populations were related to the geographical distances (r > 0.5), i.e., they conformed to the IBD (isolation by distance) model, as expected from UPGMA (unweighted pair group method
with arithmetic averages) cluster analysis. As a whole, the high genetic structuring between the four S. thunbergii populations along distant locations was clearly indicated in the RAPD and ISSR analyses (r > 0.8) in our study. 相似文献
7.
M. K. Das R. Dhamodharan S. L. Hoti A. P. Dash 《World journal of microbiology & biotechnology》2011,27(6):1525-1530
Wuchereria bancrofti, a nematode parasite, is responsible for causing 90% of lymphatic filariasis infection in the world. In India, W. bancrofti exists in two physiological forms, nocturnally periodic in the main land and diurnally sub-periodic in Car Nicobar group
of islands. Differentiation of these two parasitic forms by conventional microscopic methods difficult requiring good skill
and hence tedious. Therefore, we developed a simple and rapid Random Amplified Polymorphic DNA (RAPD) assay to differentiate
these parasitic forms. Also, the phylogenetic relationship between periodic and sub-periodic W. bancrofti and also Brugia malayi populations was analyzed using RAPD profile generated. Distinct RAPD profiles were observed among the three parasites with
the formation of three distinct clusters in the phylogenetic tree. Substantial genetic diversity (Nei’s genetic diversity
H) was observed among periodic (H = 0.0577) and sub-periodic (H = 0.1415) W. bancrofti populations. 相似文献
8.
Molecular genetic fingerprints of nine Curcuma species from Northeast India were developed using PCR-based markers. The aim involves elucidating there intra- and inter-specific
genetic diversity important for utilization, management, and conservation. Twelve random amplified polymorphic DNA (RAPD),
19 Inter simple sequence repeats (ISSRs), and four amplified fragment length polymorphism (AFLP) primers produced 266 polymorphic
fragments. ISSR confirmed maximum polymorphism of 98.55% whereas RAPD and AFLP showed 93.22 and 97.27%, respectively. Marker
index and polymorphic information content varied in the range of 8.64–48.1, 19.75–48.14, and 25–28 and 0.17–0.48, 0.19–0.48,
and 0.25–0.29 for RAPD, ISSR, and AFLP markers, respectively. The average value of number of observed alleles, number of effective
alleles, mean Nei’s gene diversity, and Shannon’s information index were 1.93–1.98, 1.37–1.62, 0.23–0.36, and 0.38–0.50, respectively,
for three DNA markers used. Dendrograms based on three molecular data using unweighted pair group method with arithmetic mean
(UPGMA) was congruent and classified the Curcuma species into two major clusters. Cophenetic correlation coefficient between dendrogram and original similarity matrix were
significant for RAPD (r = 0.96), ISSR (r = 0.94), and AFLP (r = 0.97). Clustering was further supported by principle coordinate analysis. High genetic polymorphism documented is significant
for conservation and further improvement of Curcuma species. 相似文献
9.
Bingqing Hao Wang Li Mu Linchun Yao Li Zhang Rui Tang Mingxia Bao Weikai 《Biochemical genetics》2006,44(1-2):29-43
ISSR markers were used to analyze the genetic diversity and genetic structure of eight natural populations of Cupressus chengiana in China. ISSR analysis using 10 primers was carried out on 92 different samples. At the species level, 136 polymorphic loci were detected. The percentage of polymorphic bands (PPB) was 99%. Genetic diversity (H e) was 0.3120, effective number of alleles (A e) was 1.5236, and Shannon’s information index (I) was 0.4740. At the population level, PPB = 48%, A e=1.2774, H e=0.1631, and I=0.2452. Genetic differentiation (G st) detected by Nei’s genetic diversity analysis suggested 48% occurred among populations. The partitioning of molecular variance by AMOVA analysis indicated significant genetic differentiation within populations (54%) and among populations (46%; P < 0.0003). The average number of individuals exchanged between populations per generation (N
m
) was 0.5436. Samples from the same population clustered in the same population-specific cluster, and two groups of Sichuan and Gansu populations were distinguishable. A significantly positive correlation between genetic and geographic distance was detected (r=0.6701). Human impacts were considered one of the main factors to cause the rarity of C. chengiana, and conservation strategies are suggested based on the genetic characters and field investigation, e.g., protection of wild populations, reestablishment of germplasm bank, and reintroduction of more genetic diversity. 相似文献
10.
Allozyme variations in six natural populations of scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis>) in Turkey 总被引:3,自引:0,他引:3
Genetic variation in six natural populations of Scots pine (Pinus sylvestris L.) was determined with isoenzyme analyses. For this purpose, haploid female gametophytes of seeds and horizontal starch
gel electrophoresis technique were used. A total of 17 loci and 58 alleles were observed in studying 10 enzyme systems. The
average proportion of polymorphic loci for populations ranged from 58.8% to 70.6%. The average number of alleles per locus
per population was 2.65. The mean estimated expected heterozygosity (He) of populations was 0.294. A rather high proportion
of genetic diversity (96.4%) was due to within-population variation and the remaining (3.6%) was due to variation among populations.
The level of gene flow (Nem) was found to be 6.69 per generation. Nei’s genetic distance coefficient ranged from 0.006 to 0.027 (mean 0.017) among all
possible population pairs. The mean value of Nei’s genetic distance is similar to the values reported for other European Scots
pine populations. The low mean value of Nei’s genetic distance among populations is enough to explain low interpopulation
variation. According to genetic variation parameters, three out of six populations (Akdagmadeni-Yozgat, Refahiye-Erzincan
and Vezirkopru-Samsun) appear to be preferable populations for genetic conservation and forest tree breeding programs. 相似文献
11.
Fengjuan Zhao Fuli Liu Jidong Liu Put O. AngJr. Delin Duan 《Journal of applied phycology》2008,20(2):191-198
Sargassum muticum is important in maintaining the structure and function of littoral ecosystems, and is used in aquaculture and alginate production,
however, little is known about its population genetic attributes. In this study, random amplified polymorphic DNA (RAPD) and
inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure of four populations of S. muticum and one outgroup of S. fusiforme (Harv.) Setchell from Shandong peninsula of China. The selected 24 RAPD primers and 19 ISSR primers amplified 164 loci and
122 loci, respectively. Estimates of genetic diversity with different indicators (P%, percentage of polymorphic loci; H, the expected heterozygosity; I, Shannon’s information index) revealed low or moderate level of genetic variations within each S. muticum population, and a high level of genetic differentiations were determined with pairwise unbiased genetic distance (D) and fixation index (F
ST
) among the populations. The Mantel test showed that two types of matrices of D and F
ST
were highly correlated whether from RAPD (r = 0.9706, P = 0.009) or ISSR data (r = 0.9161, P = 0.009). Analysis of molecular
variance (AMOVA) was conducted to apportion the variations among and within the S. muticum populations. It indicated that variations among populations were higher than those within populations, being 55.82% verse
44.18% by RAPD and 55.21% verse 44.79% by ISSR, respectively. Furthermore, the Mantel test suggested that genetic differentiations
among populations were related to the geographical distances (r > 0.6), namely, conformed to the IBD (isolation by distance)
model, as expected from UPGMA (unweighted pair group method with arithmetic averages) cluster analysis. On the whole, the
high genetic structuring among the four S. muticum populations along the distant locations was clearly indicated in RAPD and ISSR analyses (r > 0.9, P < 0.05) in our study. 相似文献
12.
Random amplified polymorphic DNA (RAPD) markers were used to estimate the population structure and phylogenetic relationships
among samples of the Salmo trutta complex that inhabit the Balkan Peninsula. Five random oligodecamers were selected to amplify DNA from 140 fish from seven
populations. Using these primers, 55 discernible DNA fragments were generated, of which 50 (90.91%) were polymorphic. The
statistical results indicated that there was low genetic diversity within populations (with an average percentage of polymorphic
bands (P) of 11.69% and a Nei’s genetic diversity index (h) of 0.035), but at the same time high genetic differentiation among populations (F
ST = 0.89). The distribution of genetic diversity among Balkan trout may result from their evolutionary history and reflects
genetic drift coupled with bottleneck phenomena. Overall, RAPDs proved valuable tools for quick and reliable stock discrimination
and provided information that might be useful regarding conservation and management of trout. 相似文献
13.
Pramual P Gomontean B Buasay V Srikhamwiang N Suebkar P Niamlek C Donsinphoem Y Chalat-Chieo K 《Genetica》2009,135(1):51-57
The objectives of this study were to explore cytogenetic variation and the role of chromosomal change on local adaptation
and genetic differentiation of Chironomus circumdatus Kieffer from Thailand. A total of 1,505 larvae from 24 populations were examined cytologically. Twelve chromosomal inversions
were found and most of these (9 of 12) were rare inversions. All populations were in Hardy–Weinberg equilibrium. Significant
association (P < 0.001) between the A2 and B5 inversions was detected in one population. Population genetic structure analysis indicated significant genetic differentiation
between populations (F
ST = 0.037, P < 0.001). Geographic distance was the principal factor limiting gene flow between populations. Nei’s modified genetic distance
(D
A) between populations ranged from 0.001 to 0.011 with an average of 0.003. An UPGMA population phenogram depicting relationship
between populations based on D
A values revealed three groups of populations, group I, II and III each characterized by different inversions/inversion frequencies.
Significant correlation of inversion C3 and water temperature suggested that this inversion might have a role to play on adaptation to high temperature habitat.
However, if detection of significant population subdivision and relationship between genetic and geographic distance are taken
into account, relationship between C3 and water temperature will also be due to the effect of migration/drift alone without the effect of selection. 相似文献
14.
Melinda D. Peters Qiu-Yun Xiang David T. Thomas Jon Stucky Noah K. Whiteman 《Conservation Genetics》2009,10(1):1-14
Echinacea laevigata (Boynton and Beadle) Blake is a federally endangered flowering plant species restricted to four states in the southeastern
United States. To determine the population structure and outcrossing rate across the range of the species, we conducted AFLP
analysis using four primer combinations for 22 populations. The genetic diversity of this species was high based on the level
of polymorphic loci (200 of 210 loci; 95.24%) and Nei’s gene diversity (ranging from 0.1398 to 0.2606; overall 0.2611). There
was significant population genetic differentiation (GST = 0.294; ӨII = 0.218 from the Bayesian f = 0 model). Results from the AMOVA analysis suggest that a majority of the genetic variance is attributed to variation within
populations (70.26%), which is also evident from the PCoA. However, 82% of individuals were assigned back to the original
population based on the results of the assignment test. An isolation by distance analysis indicated that genetic differentiation
among populations was a function of geographic distance, although long-distance gene dispersal between some populations was
suggested from an analysis of relatedness between populations using the neighbor-joining method. An estimate of the outcrossing
rate based on genotypes of progenies from six of the 22 populations using the multilocus method from the program MLTR ranged
from 0.780 to 0.912, suggesting that the species is predominantly outcrossing. These results are encouraging for conservation,
signifying that populations may persist due to continued genetic exchange sustained by the outcrossing mating system of the
species. 相似文献
15.
Peter O. Aikpokpodion Juan C. Motamayor Victor O. Adetimirin Yaw Adu-Ampomah Ivan Ingelbrecht Albertus B. Eskes Raymond J. Schnell Maria Kolesnikova-Allen 《Tree Genetics & Genomes》2009,5(4):699-711
Knowledge of genebank and on-farm genetic diversity, particularly in an introduced crop species, is crucial to the management
and utilization of the genetic resources available. Microsatellite markers were used to determine genetic diversity in 574
accessions of cacao, Theobroma cacao L., representing eight groups covering parental populations in West Africa, genebank, and farmers’ populations in Nigeria.
From the 12 microsatellite markers used, a total of 144 alleles were detected with a mean allelic richness of 4.39 alleles/locus.
The largest genetic diversity was found in the Upper Amazon parent population (H
nb
= 0.730), followed by the 1944 Posnette’s Introduction (H
nb
= 0.704), and was lowest in the Local parent population (H
nb
= 0.471). Gene diversity was appreciably high in the farmers’ populations (H
nb
= 0.563–0.624); however, the effective number of alleles was lower than that found in the genebank’s Posnette’s population.
Fixation index estimates indicated deficiency of heterozygotes in the Upper Amazon and the Local parent populations (F
is
= 0.209 and 0.160, respectively), and excess of heterozygotes in the Trinitario parent population (F
is
= −0.341). The presence of inbreeding in the Local parent populations and substructure (Wahlund effect) in the Upper Amazon
were suggested for the deficiency of heterozygotes observed. Non-significant genetic differentiation observed between the
genebank’s and farmers’ populations indicated significant impact of national breeding programs on varieties grown in farmers’
plantations. From this study, we showed that appreciable genetic diversity was present in on-farm and field genebank collections
of cacao that can be exploited for crop improvement in West Africa. Suggestions for future conservation of on-farm genetic
diversity and local landraces are further discussed. 相似文献
16.
Genetic diversity and differentiation were analyzed in 11 populations of Magnolia stellata (Sieb. and Zucc.) Maxim. (Magnoliaceae) in the Tokai district, Japan. Variation at four nuclear microsatellite (nSSR) loci
was examined, three chloroplast microsatellite (cpSSR) markers were developed and 13 haplotypes identified. The 11 populations
were divided into three groups (A, B and C). Each population within the group was separated less than 40 km. Group B harbored
the highest gene diversity (H) and allelic richness (Ar) for nSSR (H=0.74 and Ar=8.02). Group C had the highest diversity of chloroplast haplotypes (H=0.79 and Ar=6.8): 2.5 times more haplotypes than the other groups. Each population contributed differently to the total diversity, with
respect to nSSR and cpSSR. AMOVA revealed that 58% of haplotypic and 15% of nSSR variation was partitioned among populations
within groups. A Mantel test revealed significant correlations between population pairwise geographic ln(distance) and FST/(1−FST) for both nSSR (r=0.479; P=0.001) and cpSSR (r=0.230; P=0.040). Dendrograms of populations for nSSR, based on Nei’s genetic distance, were constructed using UPGMA and the neighbor-joining
method. These results suggest that populations in group C have diverged from the other populations, while those in group B
are similar to each other. For group B, fragmentation between populations should be avoided in order to maintain gene flow.
For group C, the uniqueness of each population should be given the highest priority when planning genetic conservation measures
for the species. 相似文献
17.
Commiphora wightii is a medicinally important endangered species endemic to the Thar Desert of Rajasthan, India and adjoining areas of Pakistan.
The populations of this species are declining sharply because of its extensive use as a natural herb. Random amplified polymorphic
DNA analysis was conducted to find the genetic variation among 7 populations of C. wightii. Of the 100 random primers screened, 44 primers yielded 220 loci. Statistical analysis indicated low genetic diversity (H
pop = 0.0958; I = 0.1498; mean polymorphic loci = 14.28%), and high genetic differentiation among the populations (G
ST = 0.3990; AMOVA Φ
ST of 0.3390; Bayesian θ
(II) = 0.3002). The low genetic diversity may be due to geographic isolation and restricted gene flow (N
m = 0.7533) between the fragmented populations. Unsustainable utilization of the plant has fragmented the population continuum
which served the purpose of genetic exchange between populations. Mantel’s test was performed which revealed a highly significant
positive correlation between genetic and geographic distance (r
2 = 0.614, P = 0.023) among the populations studied. Low variation can also be attributed to poor seed setting and the slow growth pattern
of the species, which is also an apomict. In UPGMA dendrogram the Commiphora wightii samples were divided into two major and one minor cluster. These findings can serve as a guide to preserving the genetic
resources of this medicinal plant species. 相似文献
18.
Andrew J. Gregory Robb S. A. Kaler Thomas J. Prebyl Brett K. Sandercock Samantha M. Wisely 《Conservation Genetics》2012,13(2):465-474
Island populations and populations established by reintroductions are prone to extinction, in part because they are vulnerable
to deterministic and stochastic phenomena associated with geographic isolation and small population size. As population size
declines, reduced genetic diversity can result in decreased fitness and reduced adaptive potential, which may hinder short-
or long-term population viability. We used 32 microsatellite markers to investigate the conservation genetics of a newly established
population of Evermann’s Rock Ptarmigan (Lagopus muta evermanni) at Agattu Island, in the western Aleutian Archipelago, Alaska. We found low genetic diversity (observed heterozygosity = 0.41,
allelic richness = 2.2) and a small effective population size (N
e
= 28.6), but a relatively large N
e
/N ratio = 0.55, which was attributed to multiple paternity in 80% of the broods and low reproductive skew among males (λ = 0.29).
Moreover, successful breeding pairs were less related to each other than random male–female pairs. For conservation efforts
based on reintroductions, a mating system with high rates of multiple paternity may facilitate retention of genetic diversity,
thereby reducing the potential for inbreeding in small or isolated populations. Our results underscore the importance of quantifying
genetic diversity and understanding the breeding behavior of translocated populations. 相似文献
19.
Dysosma pleiantha, an important threatened medicinal plant species, is restricted in distribution to southeastern China. The species is capable
of reproducing both sexually and asexually. In this study, inter-simple sequence repeat marker data were obtained and analyzed
with respect to genetic variation and genetic structure. The extent of clonality, together with the clonal and sexual reproductive
strategies, varied among sites, and the populations under harsh ecological conditions tended to have large clones with relatively
low clonal diversity caused by vegetative reproduction. The ramets sharing the same genotype show a clumped distribution.
Across all populations surveyed, average within-population diversity was remarkably low (e.g., 0.111 for Nei’s gene diversity),
with populations from the nature reserves maintaining relatively high amounts of genetic diversity. Among all populations,
high genetic differentiation (AMOVA: ΦST = 0.500; Nei’s genetic diversity: G
ST = 0.465, Bayesian analysis: ΦB = 0.436) was detected, together with an isolation-by-distance pattern. Low seedling recruitment due to inbreeding, restricted
gene flow, and genetic drift are proposed as determinant factors responsible for the low genetic diversity and high genetic
differentiation observed. 相似文献
20.
Genetic diversity and structure in Fagus crenata were studied by analyzing 14 nuclear microsatellite loci in 23 populations distributed throughout the species’ range. Although
population differentiation was very low (F
ST = 0.027; R
ST = 0.041), both neighbor-joining tree and Bayesian clustering analyses provided clear evidence of genetic divergence between
populations along the Japan Sea (Japan Sea lineage) and Pacific (Pacific lineage) sides of Japan, indicating that physical
barriers to migration and gene flow, notably the mountain ranges separating the populations along the Japan Sea and Pacific
sides, have promoted genetic divergence between these populations. The two lineages of the nuclear genome are generally consistent
with those of the chloroplast genome detected in a previous study, with several discrepancies between the two genomes. Within-population
genetic diversity was generally very high (average H
E = 0.839), but decreased in a clinal fashion from southwest to northeast, largely among populations of the Japan Sea lineage.
This geographical gradient may have resulted from the late-glacial and postglacial recolonization to the northeast, which
led to a loss of within-population genetic diversity due to cumulative founder effects. 相似文献