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1.
RAPD analysis of genetic variation and dispersal of the moss Bryum argenteum in Ross Island and Victoria Land, Antarctica 总被引:1,自引:0,他引:1
The Random Amplified Polymorphic DNA technique was used to assess the level of genetic diversity in Bryum argenteum from Ross Island and southern Victoria Land, Antarctica. Samples were collected from three separate transects, and from other
geographically distinct populations within 150 km of Ross Island. Moss growth in two transects, sampled down small exposed
meltstream channels at Cape Royds and Cape Chocolate, was very sparse with no other moss colonies found within 0.4 or 4 km,
respectively. However, samples from these channels showed similar levels of genetic variation to those from a transect at
Granite Harbour, where moss colonies were large, luxuriant and turf-like between boulders. In all transects, high levels of
genetic diversity were apparent both within and between colonies, and some spatial relationships were observed down the length
of the channels, with more extensive variation at the top than the bottom of two transects. Samples from other sites in the
region showed varying but high levels of genetic diversity; overall, the majority showed some clustering according to site
of collection, with short-distance dispersal of propagules by water and transmission between sites presumably by wind. The
extensive genetic diversity observed appears mainly due to somatic mutation within colonies, with some contribution by immigration
of propagules from elsewhere into established colonies.
Accepted: 10 January 1999 相似文献
2.
Genetic diversity in the moss Hennediella heimii in Miers Valley, southern Victoria Land, Antarctica 总被引:3,自引:0,他引:3
The moss Hennediella heimii constitutes a significant proportion of the terrestrial flora of East Antarctica, especially in the McMurdo Dry Valleys region
of southern Victoria Land. This is the first investigation of the extent of genetic variation within a population of H. heimii. Random Amplified Polymorphic DNA has been used to study both genetic diversity and dispersal of this moss in Miers Valley,
southern Victoria Land. The results showed that genetic variation does occur in H. heimii (possibly due to increased exposure to UV-B irradiation), even between shoots within single colonies, and that colonies collected
from three transects along meltstreams within the valley constitute a single large population. However, comparison with samples
of the same species from nearby valleys and sites up to 500 km distant showed that the Miers Valley population is distinct
from these other populations. The results also indicate that wind plays a major role in dispersal of H. heimii in this region of Antarctica.
Accepted: 2 September 1998 相似文献
3.
RAPD profiling of genetic diversity in two populations of the moss Ceratodon purpureus in Victoria Land, Antarctica 总被引:2,自引:0,他引:2
Isolates of the moss Ceratodon purpureus were collected down a channel formed by a meltstream waterfall at Granite Harbour in Southern Victoria Land, Antarctica.
The RAPD technique was used to analyse the extent of genetic variation within clumps, between clumps, and between this population
and specimens of the same species from two other areas in Antarctica (one a few hundred metres away, the other at Edmonson
Point, 300 km further north) and from Sydney, Australia. Genetic variation was detected within and among clumps, with some
spatial structure to the population within the channel. Isolates from the nearby location were quite closely related, whereas
those from Edmonson Point formed an outgroup on a phylogenetic tree of relatedness.
Received: 10 June 1997 / Accepted: 30 September 1997 相似文献
4.
Yongshuang Xiao Yan Zhang Tianxiang Gao Takashi Yanagimoto Mamoru Yabe Yasunori Sakurai 《Environmental Biology of Fishes》2009,85(4):303-314
The genetic diversity and population genetic structure of the small yellow croaker (Larimichthys polyactis) were investigated. One hundred and fourteen individuals were sampled from 8 localities of the Yellow Sea and the northern
East China Sea. Genetic variation in DNA sequences were examined from the first hypervariable region (HVR-1) of the mitochondrial
DNA control region. High levels of haplotype diversity (h = 0.98 ± 0.87%) in the HVR-1 region were detected, indicating a high level of genetic diverstiy. A total of 84 polymorphic
sites were found, and 87 haplotypes were defined. The pairwise nucleotide differences between samples ranged from 3.83 ± 2.19
to 6.56 ± 3.25. The demographic history of L. polyactis was examined by using neutrality tests and mismatch distribution analysis, which indicated a Pleistocene population expansion
at about 49,300–197,000 years. The star burst structure of the minimum spanning tree also suggestted a very recent origin
for most haplotypes. Hierarchical molecular variance analysis (AMOVA) and conventional population Fst comparisons revealed no significant genetic structure throughout the examined range, which is inconsistent with previous findings based on the morphological and ecological studies. Long-term dispersal and high
gene flow likely have contributed to the genetically homogeneous population structure of the species. The knowledge on genetic
diversity and genetic structure will be crucial to establish appropriate fishery management stocks for the species. 相似文献
5.
Local genetic differentiation in Proteopsis argentea (Asteraceae), a perennial herb endemic in Brazil 总被引:1,自引:1,他引:0
F. F. Jesus V. N. Solferini J. Semir P. I. Prado 《Plant Systematics and Evolution》2001,226(1-2):59-68
Proteopsis argentea (Asteraceae, Vernonieae) is a perennial herb endemic to the “campos rupestres” of the Espinha?o Range in Minas Gerais, Brazil,
with fragmented populational distribution. Eleven populations were sampled, throughout the entire distribution of the species,
and assayed for isozyme variation. Low intra-population genetic diversity was found (P = 19.2; A = 1.30; He = 0.058) whereas
species level diversity was higher (P = 55.5, A = 2.0, He = 0.093). The most geographically isolated population showed exclusive
alleles at two loci, whereas two populations less than 2 km apart from each other showed inverted frequencies for two alleles.
Mean genetic identity was high (I = 0.974), but the large Fst (0.30) indicates that the species could lose an important part
of its genetic variation with the extinction of a single population. Our findings indicate that geographic isolation alone
cannot explain population differentiation: localized pollinator behaviour and selection, for example, may be contributing
to the patterns observed.
Received February 18, 2000 Accepted November 1, 2000 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.
Genetic diversity and dispersal of the moss Sarconeurum glaciale on Ross Island, East Antarctica 总被引:1,自引:0,他引:1
The extent of genetic variation and dispersal mechanisms were investigated over short distances of 1–100 m, and up to 3 km, by the random amplified polymorphic DNA (RAPD) technique, for the moss Sarconeurum glaciale , at three locations on Ross Island, Antarctica. At Arrival Heights, genetic variation occurred within single colonies, and the relationships between clumps indicated that they were dispersed down small, meltwater drainage channels by water. The genetic similarities between the colonies from Arrival Heights and others from Scott Base and Crater Hill, a few km away, together with the prevailing wind direction and absence of this moss in the intervening snow-covered area, suggested longer-distance dispersal by wind. Overall, the Ross Island samples appeared to form a single, polymorphic population that was distinct from another population at Canada Glacier, 110 km distant. Somatic mutation, rather than immigration of genetically different propagules from elsewhere, appeared to be the most probable cause of genetic variability in these haploid, vegetatively reproducing Antarctic moss populations. Initiation of recolonization of S. glaciale across a dirt track at Arrival Heights was also investigated by RAPDs, to investigate how regrowth of mosses in disturbed areas occurred in the extreme environment of Antarctica. 相似文献
8.
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
9.
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
10.
Satu Lampila Laura Kvist Ralf Wistbacka Markku Orell 《European Journal of Wildlife Research》2009,55(4):397-406
Siberian flying squirrel (Pteromys volans) has declined in Finland and it is considered an endangered species. We studied microsatellite variation in four flying squirrel
populations in a fragmented landscape in Finland to determine the amount of gene flow and genetic diversity in the populations.
Demographic data from these areas suggest that the populations are declining. All the populations are significantly differentiated
(F
ST = 0.23). The most notable result is the high degree of differentiation between two adjacent populations (F
ST = 0.11) and low genetic variability (number of alleles 3.0) in one of the populations. These findings suggest problems in
dispersal and possible fragmentation effects in the landscape where only 10–20% of habitat favorable for the flying squirrel
is left. Conservation ensuring dispersal should be urgently considered. Future studies should concentrate on the modeling
of the population viability and on the effects of inbreeding in these small populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
High levels of genetic divergence and inbreeding in populations of cupuassu (Theobroma grandiflorum)
Rafael M. Alves Alexandre M. Sebbenn Angela S. Artero Charles Clement Antonio Figueira 《Tree Genetics & Genomes》2007,3(4):289-298
Theobroma grandiflorum (cupuassu) is an important fruit tree native to the Brazilian Amazon. Establishing the genetic diversity and structure of
populations is critical to define long-term strategies for cupuassu conservation presently threatened by rapid deforestation.
Three natural populations collected at the putative center of diversity, three groups of accessions established at a germplasm
collection, and one derived from commercial plantings were analyzed. The genetic diversity was assessed using 21 polymorphic
microsatellite loci originally developed for Theobroma cacao, disclosing a total of 113 alleles. The estimated genetic diversity parameters averaged over cupuassu populations (A = 3.53 alleles per locus; H
e = 0.426; H
o = 0.346) were lower than the values reported for other Neotropical tree species. The three natural populations presented
a positive and significant fixation index (f), ranging from 0.133 to 0.234. Cupuassu apparently adhered to a general pattern of genetic diversity structure of some Neotropical
tree species occurring at low densities, with a low intrapopulation genetic diversity and important levels of endogamy, possibly
due to biparental inbreeding derived from the presence of spatial genetic structure in the populations. A high level of genetic
divergence was detected among the natural populations (θ
p = 0.301), a strong differentiation caused by limited gene flow, and suggesting that human interference in spreading and/or
stimulating plantings might have had a smaller effect than expected. The approximate location of the T. grandiflorum center of diversity could not be confirmed by analyzing natural populations from the putative region. 相似文献
12.
The Cape buffalo (Syncerus caffer caffer) is one of the dominant and most widespread herbivores in sub‐Saharan Africa. High levels of genetic diversity and exceptionally low levels of population differentiation have been found in the Cape buffalo compared to other African savannah ungulates. Patterns of genetic variation reveal large effective population sizes and indicate that Cape buffalos have historically been interbreeding across considerable distances. Throughout much of its range, the Cape buffalo is now largely confined to protected areas due to habitat fragmentation and increasing human population densities, possibly resulting in genetic erosion. Ten buffalo populations in Kenya and Uganda were examined using seventeen microsatellite markers to assess the regional genetic structure and the effect of protected area size on measures of genetic diversity. Two nested levels of genetic structure were identified: a higher level partitioning populations into two clusters separated by the Victoria Nile and a lower level distinguishing seven genetic clusters, each defined by one or two study populations. Although relatively small geographic distances separate most of the study populations, the level of genetic differentiation found here is comparable to that among pan‐African populations. Overall, correlations between conservancy area and indices of genetic diversity suggest buffalo populations inhabiting small parks are showing signs of genetic erosion, stressing the need for more active management of such populations. Our findings raise concerns about the future of other African savannah ungulates with lower population sizes and inferior dispersal capabilities compared with the buffalo. 相似文献
13.
P. M. Selkirk M. Skotnicki K. D. Adam M. B. Connett T. Dale T. W. Joe J. Armstrong 《Polar Biology》1997,18(5):344-350
Sixty-six isolates of the moss Sarconeurum glaciale were collected from sites in continental Antarctica at Ross Island, southern Victoria Land and the Vestfold Hills. Genetic
variation within and among the populations was estimated using isozymes and random amplified polymorphic DNA (RAPD) technology.
Isozyme results only reproducibly showed variation between the populations with one enzyme; RAPDs indicated significantly
higher levels of genetic variability within and among the Vestfold Hills samples than in the Ross Sea region samples. A dendrogram
produced from the RAPD bands suggested that the Ross Island and southern Victoria Land samples form one population, and those
from the Vestfold Hills form a separate and more variable population, possibly resulting from separate colonisation events
on the continent.
Received: 15 March 1996 / Accepted: 1 May 1997 相似文献
14.
Luciana Ines Oklander Martin M. Kowalewski Daniel Corach 《International journal of primatology》2010,31(5):813-832
Human-induced habitat fragmentation might seriously affect behavioural patterns and the survival of species whose ecological
requirements strongly depend on specific environmental conditions. We compared the genetic structure and dispersal patterns
of 2 populations of Alouatta caraya (Plathyrrhini, Atelidae) to understand how habitat reduction and fragmentation affect gene flow in this species. We sampled
individuals from 7 groups living in continuous forest (CF, n = 46, 22 males and 24 females), and 11 groups that inhabit a fragmented forest (FF, n = 50, 24 males and 26 females). FST values based on 11 microsatellite loci showed a recent genetic differentiation among
groups in the FF. In contrast, the CF showed no differentiation among groups. Further, FST values between sexes, as well as
kinship relationships, also exhibited differences between habitats. In the CF, both males and females disperse, leading to
nondifferentiated groups composed of adults that are not close relatives. Conversely, in the FF, some groups are differentiated,
males disperse more than females, and groups are composed of closely related adult females. Our results suggest that habitat
fragmentation modifies the dispersal patterns of black-and-gold howlers. These differences between habitats may reflect a
reduced gene flow, providing genetic evidence that suggests that habitat fragmentation severely limits the howler’s ability
to disperse. An increasing level of isolation due to uncontrolled deforestation may cause similar loss of genetic diversity
on other arboreal primates, and nonprimates that depend on forest continuity to disperse, reducing their abilities to cope
with environmental changes. 相似文献
15.
Rym Zitari-Chatti Noureddine Chatti Domenico Fulgione Immacolata Caiazza Gennaro Aprea Ali Elouaer Khaled Said Teresa Capriglione 《Genetica》2009,136(3):439-447
In this study we analysed mitochondrial DNA variation in Penaeus kerathurus prawns collected from seven locations along a transect across the Siculo–Tunisian region in order to verify if any population
structuring exists over a limited geographical scale and to delineate the putative transition zone with sufficient accuracy.
Partial DNA sequences of COI and 16S genes were analysed. In contrast to the highly conservative 16S gene, the COI sequences
exhibited sufficient diversity for population analysis. The COI gene revealed low levels of haplotype and nucleotide diversities.
The size of the annual landings of this commercial species suggests large population sizes. Hence, the low genetic diversity
detected in this study could indicate a possible reduction in effective population sizes in the past. We detected significant
genetic differentiation between eastern and western populations likely due to restricted gene flow across the Siculo–Tunisian
boundary. We discuss the different evolutionary forces that may have shaped the genetic variation and suggest that the genetic
divide is probably maintained by present-day dispersal limitation.
R. Zitari-Chatti and N. Chatti are contributed equally to the work. 相似文献
16.
The random amplified polymorphic DNA (RAPD) technique, and DNA sequencing of the conserved nuclear ribosomal DNA internal transcribed spacer region (ITS1-5.8S-ITS2), have been used to assess levels of genetic diversity in the moss Ceratodon purpureus from several locations in Australasia, subantarctic Heard and Macquarie Islands, and continental Antarctica. Populations from Heard and Macquarie Islands and from Antarctica maintain high levels of genetic variation. Both within- and among-colony variation were observed at these locations. DNA sequence analysis showed that samples from the Ross Sea region of Antarctica were most closely related to colonies from Casey and Macquarie Island, and that one colony from Heard Island was most closely related to one from Europe. DNA sequence data separated two Australian populations from the Antarctic and subantarctic group on a dendrogram. Detailed RAPD analysis of a single colony from continental Antarctica demonstrated that mutation probably causes the high variability observed in this moss. DNA sequencing and RAPD analysis are complementary techniques for genetic investigation of Antarctic moss populations.Jenny Ninham was an integral part of this research team for several years. Unfortunately she did not live to see these results published. 相似文献
17.
Changkyun Kim Jongduk Jung Hye Ryun Na Suk Weon Kim Wei Li Yasuro Kadono Hyunchur Shin Hong-Keun Choi 《Journal of Plant Biology》2012,55(1):81-91
Genetic variation of nuclear ribosomal ITS (nrITS) and chloroplast DNA (cpDNA) regions was investigated in Brasenia schreberi (Cabombaceae) to assess the population structure and to infer the evolutionary relationship among 12 populations distributed
in South Korea. The combined sequence of the two regions was aligned to 2,069 bp, of which 28 sites were variable. In total,
20 genotypes were identified from 240 individuals of B. schreberi. Genotype diversity (Gd) and nucleotide diversity (Pi) on Jeju Island (Gd = 0.2511, Pi = 0.00012) were higher than those
of the mainland of South Korea (Gd = 0.1358, Pi = 0.00005). The relatively low level of genetic variation of the mainland
populations is associated with its higher genetic differentiation (G
ST = 0.095 on mainland and 0.039 on Jeju Island) and human activities. Minimum spanning network analysis demonstrated that the
investigated populations of B. schreberi were subdivided into two geographical groups: the mainland of South Korea and Jeju Island. In addition, analysis of molecular
variation showed that a large proportion (73.55%) of genetic differentiation existed between the two regions. These results
strongly suggest the presence of significant barriers to gene flow between regions. Thus, the management unit for B. schreberi should be carefully designed to avoid the potential risk that can results from the admixture of individuals from the mainland
and Jeju Island regions. 相似文献
18.
Jinliang Zhao Yang Cao Sifa Li Jiale Li Yanfei Deng Guoqing Lu 《Environmental Biology of Fishes》2011,90(1):85-93
Ample studies have been conducted to investigate the population genetic structure of grass carp Ctenopharyngodon idella in the Yangtze River, China. However, samples from the upper reaches were not included. In this study, we collected samples
from the entire river, including three locations in the upper reaches: Yibin, Banan and Yunyang, two locations in the middle
reaches: Shishou and Ruichang and one location in the lower reaches: Hanjiang, and sequenced three mitochondrial coding genes
(ND5, ND6 and Cytb) and one control region (i.e., the D-loop). Nineteen haplotypes were observed in grass carp of the Yangtze River through
the analysis of combined sequence data sets (around 4428 bp). Haplotype diversity indices (0.6000 ∼ 0.9333) and nucleotide
diversity indices (0.0002 ∼ 0.0020) demonstrated low genetic diversity in the Yangtze grass carp. The analysis of molecular
variance and the fixation index (F
ST = 0.0202) revealed insignificant genetic difference between samples from different reaches. Two monophyletic lineages of
haplotypes were identified, with the lineage A experiencing potential expansion events. Along with previous findings, this
study provides a better understanding of genetic diversity and variation of grass carp in the Yangtze River and will be served
as an important baseline to evaluate the long-term impact of the Three Gorges Dam and other hydroelectric facilities on fish
biodiversity. 相似文献
19.
Rosane G. Collevatti Raquel Estolano Silmara F. Garcia John D. Hay 《Tree Genetics & Genomes》2009,6(4):555-564
We investigated pollen dispersal and breeding structure in the tropical tree species Caryocar brasiliense Camb. (Caryocaraceae), using genetic data from ten microsatellite loci. All adult trees (101) within a patch of 8.3 ha were
sampled, and from these adults 18 open-pollinated maternal progeny arrays were analyzed (280 seeds from 265 fruits). Most
fruits presented only one seed (median equal to 1.000) and mean number of ripened seeds per fruit was 1.053 (SD = 0.828).
Our results showed that C. brasiliense presents a mixed-mating system, with 11.4% of self-pollination, multilocus outcrossing rate of t
m = 0.891 ± 0.025, and high probability of full-sibship within progeny arrays (r
p = 0.135 ± 0.032). Outcrossing rate and self-pollination varied significantly among mother trees. We could detect a maximum
pollen dispersal distance of ∼500 m and a mean pollen dispersal distance of ∼132 m. However, most pollination events (80%)
occurred at distances less than 200 m. Our results also indicated that pollen dispersal is restricted to a neighborhood of
5.4 ha with rare events of immigration (∼1% N
e
m = 0.35). C. brasiliense also presents a significant but weak spatial genetic structure (Sp = 0.0116), and extension of pollen dispersal distance was greater than seed dispersal (N
b = 86.20 m). These results are most likely due to the foraging behavior of pollinators that may have limited flight range.
The highly within-population synchronous flowering, high population density, and clumped distribution reinforce pollinator
behavior and affect residence time leading to a short-distance pollen dispersal. 相似文献
20.
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