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1.
Identifying factors that cause genetic differentiation in plant populations and the spatial scale at which genetic structuring can be detected will help to understand plant population dynamics and identify conservation units. In this study, we determined the genetic structure and diversity of Pterocarpus officinalis, a widespread tropical wetland tree, at three spatial scales: (1) drainage basin “watershed” (<10 km), (2) within Puerto Rico (<100 km), and (3) Caribbean-wide (>1000 km) using AFLP. At all three spatial scales, most of the genetic variation occurred within populations, but as the spatial scale increased from the watershed to the Caribbean region, there was an increase in the among population variation (ΦST=0.19 to ΦST=0.53). At the watershed scale, there was no significant differentiation (P=0.77) among populations in the different watersheds, although there was some evidence that montane and coastal populations differed (P<0.01). At the island scale, there was significant differentiation (P<0.001) among four populations in Puerto Rico. At the regional scale (>1000 km), we found significant differentiation (P<0.001) between island and continental populations in the Caribbean region, which we attributed to factors associated with the colonization history of P. officinalis in the Neotropics. Given that genetic structure can occur from local to regional spatial scales, it is critical that conservation recommendations be based on genetic information collected at the appropriate spatial scale. 相似文献
2.
?těpánka ?í?anová Josef Bryja Jean-Fran?ois Cosson Csongor Gedeon Luká? Choleva Michal Ambros Franti?ek Sedlá?ek 《Conservation Genetics》2011,12(4):1115-1129
Habitat fragmentation may influence the genetic make-up and adaptability of endangered populations. To facilitate genetic
monitoring of the endangered European ground squirrel (EGS), we analyzed 382 individuals from 16 populations in Central Europe,
covering almost half of its natural range. We tested how fragmentation affects the genetic architecture of presumably selectively
neutral (12 microsatellites) and non-neutral (the major histocompatibility class II DRB gene) loci. Spatial genetic analyses
defined two groups of populations, “western” and “eastern”, with a significantly higher level of habitat fragmentation in
the former group. The highly fragmented western populations had significantly lower genetic diversity in both types of markers.
Only one allele of the DRB gene predominated in populations of the western group, while four alleles were evenly distributed
across the eastern populations. Coefficient of inbreeding values (F
IS) calculated from microsatellites were significantly higher in the western (0.27–0.79) than in eastern populations (−0.060–0.119).
Inter-population differentiation was very high, but similar in both groups (western F
ST = 0.23, eastern F
ST = 0.25). The test of isolation by distance was significant for the whole dataset, as well as for the two groups analyzed
separately. Comparison of genetic variability and structure on microsatellites and the DRB gene does not provide any evidence
for contemporary selection on MHC genes. We suggest that genetic drift in small bottlenecked and fragmented populations may
overact the role of balancing selection. Based on the resulting risk of inbreeding depression in the western populations,
we support population management by crossbreeding between the western and eastern populations. 相似文献
3.
We assessed genetic variation in a total of 22 populations of the tree species Cordia africana Lam. in Ethiopia and analyzed the country-wide impact of population history, forest disturbance and alteration of land use
on extant intraspecific diversity. Amplified Fragment Length Polymorphisms (AFLPs) and chloroplast microsatellite markers
were investigated. The analyses of the AFLP data revealed high diversity in all investigated populations: the percentage of
polymorphic loci (PPL) ranged from 62.2% to 92.2% and Nei's gene diversity from 0.220 to 0.320 within the populations. The
mean PPL and the mean diversity within populations were 85.7% and 0.287, respectively. The analysis of molecular variance
revealed a moderate level of differentiation (ΦST = 0.07, p < 0.001) among the populations. The Mantel test proved a significant but low correlation (r = 0.31, p < 0.001) between the geographic distance and the genetic differentiation matrices. Only three different cpDNA haplotypes
were observed; no more than two haplotypes were found in any population. The dominant haplotype with an overall frequency
of 81% was observed in all populations. The level of differentiation among the populations was comparatively low at chloroplast
DNA (G
ST = 0.18, R
ST, N
ST = 0.22). The observed patterns and levels of genetic variation within and among the populations indicate that efficient gene
flow via pollen and seed is likely to be the main factor contributing to the maintenance of genetic diversity in natural and
disturbed conditions. 相似文献
4.
Yoshiaki Tsuda Haruo Sawada Takafumi Ohsawa Katsuhiro Nakao Hiroki Nishikawa Yuji Ide 《Tree Genetics & Genomes》2010,6(3):377-387
We evaluated the genetic structure of 16 Betula maximowicziana populations in the Chichibu mountain range, central Japan, located within a 25-km radius; all but two populations were at
altitudes of 1,100–1,400 m. The results indicate the effects of geographic topology on the landscape genetic structure of
the populations and should facilitate the development of local-scale strategies to conserve and manage them. Analyses involving
11 nuclear simple sequence repeat loci showed that most populations had similar intrapopulation genetic diversity parameters.
Population differentiation (F
ST = 0.021, G′ST = 0.033) parameters for the populations examined were low but were relatively high compared to those obtained in a previous
study covering populations in a much larger area with a radius of approximately 1,000 km (F
ST = 0.062, G′ST = 0.102). Three populations (Iriyama, Kanayamasawa, and Nishizawa) were differentiated from the other populations by Monmonier’s
and spatial analysis of molecular variance algorithms or by STRUCTURE analysis. Since a high mountain ridge (nearly 2,000 m)
separates the Kanayamasawa and Nishizawa populations from the other 14 populations and the Kanayamasawa and Nishizawa populations
are themselves separated by another mountain ridge, the genetic structure appears to be partly due to mountain ridges acting
as genetic barriers and restricting gene flow. However, the Iriyama population is genetically different but not separated
by any clear geographic barrier. These results show that the landscape genetic structure is complex in the mountain range
and we need to pay attention, within landscape genetic studies and conservation programs, to geographic barriers and local
population differentiation. 相似文献
5.
P. Marchelli C. Baier C. Mengel B. Ziegenhagen L. A. Gallo 《Conservation Genetics》2010,11(3):951-963
Fragmentation of the habitat due to glaciations, fires and human activities affected the distribution range of Araucaria araucana in southern South America. On the borders of the Argentinean Patagonian steppe, the species is restricted to isolated patches
without natural regeneration. Our objective is to test the hypothesis that these populations are relicts of pre-Pleistocene
origin. A total of 224 individuals from 16 populations were sampled. Twenty chloroplast microsatellites, 19 non-coding chloroplast
DNA regions and eight mitochondrial DNA fragments were screened for polymorphisms. A low transferability rate of universal
primers from Pinaceae and also a low variation were detected for this ancient species. Only one non-coding region of the chloroplast
DNA showed polymorphism allowing the identification of five haplotypes. A low genetic differentiation (G
ST
= 0.11; G′
ST
= 0.267) and lack of geographic structure was found. Allelic richness was lower and genetic differentiation higher among
the eastern isolated populations, suggesting a long lasting persistence. Conservation guidelines are given for these relictual
populations, which are located outside the limits of the National Parks. 相似文献
6.
Mao-feng Yue Ren-chao Zhou Ye-lin Huang Guo-rong Xin Su-hua Shi Li Feng 《Journal of Plant Biology》2010,53(2):165-171
High levels of genetic variation enable species to adapt to changing environments and provide plant breeders with the raw
materials necessary for artificial selection. In the present study, six AFLP primer pairs were used to assess the genetic
diversity of Desmodium triflorum (L.) DC. from 12 populations in South China. A high percentage of polymorphic loci (P = 76.16%) and high total gene diversity (H
T = 0.310) were found, indicating that the genetic diversity of D. triflorum is high at the species level. Genetic diversity was also relatively high at the population level (P = 55.85%, H
e = 0.230). The coefficient of gene differentiation among populations (G
ST) was 0.255, indicating that while most genetic diversity resided within populations, there was also considerable differentiation
among populations. AMOVA also indicated 24.29% of the total variation to be partitioned among populations (ΦST = 0.243). UPGMA clustering analysis based on genetic distances showed that the 12 populations could be separated into three
subgroups: an eastern, a western, and a central-southern subgroup. However, a Mantel test revealed no significant correlation
(r = 0.286, p = 0.983) between the geographical distances and genetic distances separating these populations; mountain barriers to gene
flow and human disturbance may have confounded these correlations. The present study has provided some fundamental genetic
data that will be of use in the exploitation of D. triflorum. 相似文献
7.
Kenichi Ohara Momoko Hotta Daisuke Takahashi Takashi Asahida Hitoshi Ida Tetsuya Umino 《Ichthyological Research》2009,56(4):373-379
The genetic diversity and relationship among four morphotypes of Rhinogobius sp. OR, Gobiidae (“Tōshoku,” “Shinjiko,” “Gi-tōshoku,” and “Shimahire”) were investigated with seven microsatellite DNA loci,
and amphidromy of these morphotypes was verified by strontium (Sr) and calcium (Ca) deposition in the otolith. Samples of
“Tōshoku,” “Shinjiko,” “Gi-tōshoku,” and “Shimahire” were collected from, respectively, three, three, two, and four locations
in Japan. Microsatellite analysis detected high genetic diversity (based on the number of alleles, allelic richness, and average
observed heterozygosity) in the “Tōshoku” and “Shinjiko” morphotypes relative to the “Shimahire” morphotype; the “Gi-tōshoku”
morphotype had an intermediate level of variation. Almost all pairwise F
ST values were significantly different from zero (P < 0.001), except between two populations of “Tōshoku.” Clear genetic independence was observed between the “Shinjiko” and
“Shimahire” morphotypes in the Maruyama River. A principle component analysis based on microsatellite data indicated that
the “Tōshoku,” “Shinjiko,” and “Gi-tōshoku” morphotypes were genetically similar. Furthermore, the three populations of “Tōshoku”
were closely related each other, and two of those collected from the Lake Biwa system were a single population. There was,
however, a high degree of genetic differentiation between “Shimahire” and the other morphotypes; moreover, there was high
genetic divergence among four populations of the “Shimahire” morphotype. Amphidromous migratory histories were indicated by
Sr:Ca ratios in two of three populations of the “Shinjiko” morphotype and in one of two “Gi-tōshoku” morphotypes, whereas
all populations of the “Shimahire” morphotype were freshwater residents. The large genetic divergence and low genetic diversity
in “Shimahire” are likely related to migration history. 相似文献
8.
N. N. Timoshkina A. E. Barmintseva A. V. Usatov N. S. Mugue 《Russian Journal of Genetics》2009,45(9):1098-1106
Three populations (Azov, Caspian, and Black Sea) of Russian sturgeon Acipenser queldenstaedtii were tested for polymorphism at nuclear (RAPD and microsatellites) and mitochondrial (PCR identification of two mitotypes)
markers. In addition, morphometric analysis of he representatives of Azov population was carried out. According to the morphological
characters, the Black Sea population occupied an intermediate position between the Caspian and Azov populations, reflecting
the phylogeography of this species. In agreement with the morphometric data, genetic distances (the data of STR analysis)
also placed the Black Sea population between the Caspian and Azov populations (F
ST = 0.058 and 0.043). The genetic distance between the Azov and Caspian population was somewhat higher (F
ST = 0.070). The highest allelic polymorphism at four microsatellite loci was found observed in Caspian population, while the
lowest polymorphism was in the Sea of Azov. RAPD analysis distinguished high polymorphism within the populations, although
it was not feasible for interpopulation analysis. Using the method differentiating the “baerii-like” and typical “gueldenstaedtii”
mitotypes, the absence of the “baerii-like” marker in the Black Sea population was demonstrated. The frequency of this marker
in Caspian and Azov populations constituted 31.1 and 1.8%, respectively. Possible evolutionary reasons for the interpopulation
differences observed are discussed. 相似文献
9.
The Risso’s dolphin (Grampus griseus) has a worldwide distribution, but little is known about their population genetic structure. Local coastal populations are
never known to be abundant, and are sometimes under anthropogenic impact. Therefore the question of regional differentiation
by genetic drift and overall diversity levels is of conservation interest. Here we present preliminary data that clearly indicate
genetic differentiation and lower genetic diversity of a population sampled in UK waters (primarily from the Western Isles,
Scotland) compared to a Mediterranean sample. Significant differentiation was found in comparison with a sample from the Mediterranean
for both microsatellite DNA markers (F
ST = 0.0296) and mtDNA sequence data (F
ST = 0.260; ϕ
ST = 0.542). Allelic diversity was lower in the UK for nearly all loci. 相似文献
10.
Climatic oscillations during the Quaternary strongly affected the distribution of warm-temperate tree species, which experienced
local restrictions into ice-free areas and posterior expansions. To evaluate the impact of these range movements on the genetic
structure of populations, we performed a phylogeographical analysis of the species Nothofagus obliqua with chloroplast DNA markers. A total of 27 populations covering the whole natural distribution range were analyzed using
polymerase chain reaction-restriction fragment length polymorphism. Diversity (h
T, h
S), allelic richness (r
g), and differentiation among populations for unordered (G
ST) and ordered alleles (N
ST) were calculated. The relationships among haplotypes were evaluated by the construction of a minimum spanning network. The
spatial distribution of the genetic variation was analyzed through a Mantel test and with a nested analysis of molecular variance
to differentiate between geographic regions. The screening of 11 non-coding regions allowed the identification of 14 haplotypes.
A high genetic differentiation was detected (N
ST = 0.875 and G
ST = 0.824) with the existence of phylogeographic structure (p < 0.05). The distribution of the genetic variation was partially explained by the topography of the region when the populations
were divided longitudinally into Coastal Mountains, Central Valley, and Andes Mountains (ϕ
RT = 0.093, p = 0.001). In agreement with pollen records, our results support the hypothesis of Coastal refuges since the region harbors
high diversity together with older and private haplotypes. Long-lasting persistence of some Coastal populations without contribution
to re-colonization is proposed. Additional refuges are also postulated along the Andes and Longitudinal Valley. Survival in
multiple glacial refuges is discussed together with the possible migratory routes. 相似文献
11.
The genetic diversity and population structure of the vulnerable Chinese Egret (Egretta eulophotes) were surveyed in the present study from three archipelagoes that cover the most southerly to the very northerly parts of
the Chinese distribution range of this species, using a 433-bp fragment of the mitochondrial control region (CR). Among 90
individual samples, 31 different haplotypes were defined by 30 polymorphic sites. Overall haplotype diversity, nucleotide
diversity and mean sequence divergence (p-distance) of this egret were 0.920, 0.0088 and 1.11%, respectively. NJ tree and
parsimony network for the CR haplotypes of the Chinese Egret showed little genetic structure, and analysis of molecular variance
indicated low but significant genetic differentiation (haplotype-based ΦST = 0.03267, P < 0.05 and distance-based ΦST = 0.04194, P < 0.05) among populations. The significant Fu’s F
S
tests (Fu’s F
S
= −16.946, P < 0.01) and mismatch distribution analysis (τ = 4.463, SSD = 0.0081, P = 0.12) suggested that the low genetic differentiation and little geographical structure of the genetic differentiation might
be explained by the population expansion. The Mantel test (haplotype-based F
ST, r = 0.639, P = 0.34 and distance-based F
ST, r = 0.947, P = 0.15) suggest that the significant genetic differentiation among populations was likely due to isolation by distance. 相似文献
12.
Emily K. Latch Guha Dharmarajan Jeffrey C. Glaubitz Olin E. Rhodes Jr. 《Conservation Genetics》2006,7(2):295-302
Traditional methods for characterizing genetic differentiation among populations rely on a priori grouping of individuals. Bayesian clustering methods avoid this limitation by using linkage and Hardy–Weinberg disequilibrium to decompose a sample of individuals into genetically distinct groups. There are several software programs available for Bayesian clustering analyses, all of which describe a decrease in the ability to detect distinct clusters as levels of genetic differentiation among populations decrease. However, no study has yet compared the performance of such methods at low levels of population differentiation, which may be common in species where populations have experienced recent separation or high levels of gene flow. We used simulated data to evaluate the performance of three Bayesian clustering software programs, PARTITION, STRUCTURE, and BAPS, at levels of population differentiation below F
ST=0.1. PARTITION was unable to correctly identify the number of subpopulations until levels of F
ST reached around 0.09. Both STRUCTURE and BAPS performed very well at low levels of population differentiation, and were able to correctly identify the number of subpopulations at F
ST around 0.03. The average proportion of an individual’s genome assigned to its true population of origin increased with increasing F
ST for both programs, reaching over 92% at an F
ST of 0.05. The average number of misassignments (assignments to the incorrect subpopulation) continued to decrease as F
ST increased, and when F
ST was 0.05, fewer than 3% of individuals were misassigned using either program. Both STRUCTURE and BAPS worked extremely well for inferring the number of clusters when clusters were not well-differentiated (F
ST=0.02–0.03), but our results suggest that F
ST must be at least 0.05 to reach an assignment accuracy of greater than 97%. 相似文献
13.
Tomomi Dan Hajime Ikeda Yuki Mitsui Yuji Isagi Hiroaki Setoguchi 《Conservation Genetics》2009,10(4):859-867
Continental island systems harbour relict biota and populations that might have migrated during glacial periods due to the
formation of landbridges. Here we analysed the genetic structure of relict populations of the temperate plant Shortia rotundifolia on the subtropical island of Iriomotejima, Japan. This plant, which inhabits riparian environments, is designated “near threatened”.
Only five extant populations have been found on the island. Our analyses of 10 nuclear microsatellite loci detected genetic
diversity of H
E = 0.488 and H
O = 0.358 for all populations of S. rotundifolia on the island. A high inbreeding coefficient for all populations together (F
IS = 0.316) and each population separately (F
IS = 0.258–0.497) might be attributable to crossing among closely related descendants within a population, an idea that is supported
by the relatedness coefficient. These results and an examination of the populations’ demographic histories suggest that the
extant populations on Iriomotejima have not experienced a recent population bottleneck. The five extant populations were genetically
differentiated (F
ST = 0.283; P < 0.001), suggesting low seed dispersal by gravity and/or low pollen flow via pollinators in the riparian environment. In
addition, population differentiation was not related to genetic distance, implying that at one time, ancestral populations
might have been distributed over a wider area of the island. However, population fragmentation and range contraction might
have occurred at random during the postglacial period. 相似文献
14.
L.-z. Gao S. G. De-y. Hong 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(3):494-502
In order to determine the genetic diversity and genetic structure of populations in common wild rice Oryza rufipogon, an endangered species, allozyme diversity was analyzed using 22 loci in 607 individuals of 21 natural populations from the
Guangxi, Guangdong, Hainan, Yunnan, Hunan, Jiangxi and Fujian provinces in China. The populations studied showed a moderate
allozyme variability (A=1.33, P=22.7%, Ho=0.033 and He=0.068), which was relatively high for the genus Oryza. The levels of genetic diversity for Guangxi and Guangdong were significantly higher than those for the other regions, and
thus South China appeared to be the center of genetic diversity of O. rufipogon in China. A moderate genetic differentiation (FST=0.310, I=0.964) was found among the populations studied. Interestingly, the pattern of population differentiation does not
correspond to geographic distance. An estimate of the outcrossing rate (t=0.324) suggests that the species has a typical mixed-mating
system. The deficit of heterozygotes (F=0.511) indicates that some inbreeding may have taken place in outcrossing asexual
populations because of intra-clone outcrossing events and ”isolation by distance” as a result of human disturbance. In order
to predict the long-term genetic survival of fragmented populations, further studies on gene flow among the remaining populations
and the genetic effects of fragmentation are proposed. Finally, some implications for the conservation of endangered species
are suggested.
Received: 22 June 1999 / Accepted: 20 December 1999 相似文献
15.
Cedrus libani of Lebanon is a valuable natural resource and the dominant species in its natural ecosystem. Intense and diverse anthropogenic
pressures over historical times raised concerns about its genetic vigor and continued survival. Our investigation of the genetic
diversity included samples from all remnant natural populations. Assessment of the genetic diversity using random amplified
polymorphic DNA markers revealed the persistence of considerable variation distributed within populations with low population
differentiation corroborated by Bayesian and analysis of molecular variance estimates (G
ST = 0.07, Φ
ST = 0.09). Individual assignment tests were carried out to investigate measures of gene flow. Inferences concluded that this
natural heritage is not currently threatened by inbreeding or by random genetic drift. Correlation studies investigated possible
effects of spatial distribution and environmental conditions on genetic structure. A climatic trend corresponding to a temperature–humidity
gradient correlated significantly with the level of genetic diversity, while the edaphic variation did not. 相似文献
16.
Lan Q Shen M Garcia-Rossi D Chanock S Zheng T Berndt SI Puri V Li G He X Welch R Zahm SH Zhang L Zhang Y Smith M Wang SS Chiu BC Linet M Hayes R Rothman N Yeager M 《Immunogenetics》2007,59(11):839-852
Selection and genetic drift can create genetic differences between populations. Cytokines and chemokines play an important
role in both hematopoietic development and the inflammatory response. We compared the genotype frequencies of 45 SNPs in 30
cytokine and chemokine genes in two healthy Chinese populations and one Caucasian population. Several SNPs in IL4 had substantial genetic differentiation between the Chinese and Caucasian populations (F
ST ~0.40), and displayed a strikingly different haplotype distribution. To further characterize common genetic variation in
worldwide populations at the IL4 locus, we genotyped 9 SNPs at the IL4 gene in the Human Diversity Panel’s (N = 1056) individuals from 52 world geographic regions. We observed low haplotype diversity, yet strikingly different haplotype
frequencies between non-African populations, which may indicate different selective pressures on the IL4 gene in different parts of the world. SNPs in CSF2, IL6, IL10, CTLA4, and CX3CR1 showed moderate genetic differentiation between the Chinese and Caucasian populations (0.15 < F
ST < 0.25). These results suggest that there is substantial genetic diversity in immune genes and exploration of SNP associations
with immune-related diseases that vary in incidence across these two populations may be warranted. 相似文献
17.
Variation of DNA methylation is thought to play an important role for rapid adjustments of plant populations to dynamic environmental conditions, thus compensating for the relatively slow response time of genetic adaptations. However, genetic and epigenetic variation of wild plant populations has not yet been directly compared in fast changing environments. Here, we surveyed populations of Viola elatior from two adjacent habitat types along a successional gradient characterized by strong differences in light availability. Using amplified fragment length polymorphisms (AFLP) and methylation‐sensitive amplification polymorphisms (MSAP) analyses, we found relatively low levels of genetic (H′gen = 0.19) and epigenetic (H′epi = 0.23) diversity and high genetic (?ST = 0.72) and epigenetic (?ST = 0.51) population differentiation. Diversity and differentiation were significantly correlated, suggesting that epigenetic variation partly depends on the same driving forces as genetic variation. Correlation‐based genome scans detected comparable levels of genetic (17.0%) and epigenetic (14.2%) outlier markers associated with site specific light availability. However, as revealed by separate differentiation‐based genome scans for AFLP, only few genetic markers seemed to be actually under positive selection (0–4.5%). Moreover, principal coordinates analyses and Mantel tests showed that overall epigenetic variation was more closely related to habitat conditions, indicating that environmentally induced methylation changes may lead to convergence of populations experiencing similar habitat conditions and thus may play a major role for the transient and/or heritable adjustment to changing environments. Additionally, using a new MSAP‐scoring approach, we found that mainly the unmethylated (?ST = 0.60) and CG‐methylated states (?ST = 0.46) of epiloci contributed to population differentiation and putative habitat‐related adaptation, whereas CHG‐hemimethylated states (?ST = 0.21) only played a marginal role. 相似文献
18.
Warangkana Prakoon Suriyan Tunkijjanukij Thuy T. T. Nguyen Uthairat Na-Nakorn 《Marine biotechnology (New York, N.Y.)》2010,12(5):506-515
The culture of green mussel (Perna viridis) in the Gulf of Thailand depends on natural spat which are believed to come from spawning grounds adjacent to major river
mouths. In the present paper, genetic diversity of spatial and temporal populations of green mussel in the Gulf of Thailand
was investigated using five microsatellite loci. The results showed moderate genetic variation of all 11 populations (averaged
number of alleles per locus, A = 10.4–12.2; effective number of alleles per locus, A
e = 5.36–6.59; mean allelic richness, A
r = 10.23–12.06; observed heterozygosity, H
o = 0.52–0.63, and expected heterozygosity, H
e = 0.66–0.73) without significant differences among populations. No sign of bottleneck or genetic disequilibrium was observed.
Genetic differentiation among spatial populations was low (F
ST = 0.0046, CI0.95 = 0.0020–0.0083 for the samples collected in January, 2007, and F
ST = 0.0088, CI0.95 = 0.0010–0.0162 for the samples collected in July, 2007) while temporal variation was significant as revealed by the analysis
of molecular variance. Multidimensional scaling separated temporal population groups with minor exception. The assignment
test revealed that most of the recruits were from other populations. 相似文献
19.
Brandt’s vole (Lasiopodomys brandtii) distribution is discontinuous in Inner Mongolia with some populations isolated from others. Recently, some isolated populations
have suffered extinction, and the factors responsible remain elusive. Genetic drift is one of the processes affecting population
genetic differentiation, and can play a substantial role in the divergence of small, isolated populations. Using seven microsatellite
markers, we genotyped four geographically isolated populations of Brandt’s vole, all of which exhibit episodic fluctuations
in population density. The results showed a strong genetic differentiation among the geographically distinct populations (total
F
ST = 0.124) and in particular, one population (Zhengxiangbaiqi) was isolated from all others (F
ST values were greatest between Zhengxiangbaiqi and other populations). Furthermore, high levels of inbreeding (F
IS values ranged from 0.205 to 0.290) within each distinct population suggest that inbreeding has and is likely occurring in
Brandt’s vole populations. These processes can decrease average individual fitness and consequently increase the risk of extinction
of the species. 相似文献
20.
Susumu Goto Yoshiaki Tsuda Yukihiro Koike Chunlan Lian Yuji Ide 《Ecological Research》2009,24(6):1267-1277
To evaluate the effects of landscape and demographic history on genetic variation in Picea glehnii at a regional scale we have investigated the genetic diversity and genetic differentiation of P. glehnii populations in the Furano region, central Hokkaido, Japan, using seven simple sequence repeat (SSR) markers. We found significant
correlations between elevation and genetic diversity parameters. The value of A
[46] increased and the value of F
IS decreased with increasing elevation, while F
IS values were not significantly different from 0 in any of the populations. Significant recent bottlenecks were detected for
isolated populations at low-elevation sites and for relatively large populations at moderate- and high-elevation sites. Evolutionary
events pre-dating the Holocene should be taken into consideration, as elevational gradients should be with respect to locally
adapted traits such as flowering phenology, However, the palynological data from the Holocene in this region suggest that
the distribution pattern of genetic diversity of P. glehnii detected here may have been influenced by past demographic history related to the elevation shifts in this species’ distribution
associated with climate change during this period. Population differentiation was low, with F
ST and G′ST values of 0.022 and 0.065, respectively. However, genetic boundaries were detected around one swamp population (C13). Therefore,
significant isolation by distance (IBD) was not detected when all populations were considered, but there was significant IBD
when the C13 population was excluded. Information on genetic diversity and genetic differentiation at the regional scale may
be useful for selecting seed sources for afforestation programs for P. glehnii. 相似文献