共查询到20条相似文献,搜索用时 31 毫秒
1.
Kouichi Kawamura Masashi Kubota Miki Furukawa Yasushi Harada 《Conservation Genetics》2007,8(5):1163-1176
The amago salmon, Oncorhynchus masou ishikawae, is an endemic subspecies of O. masou in Japan. Owing to the extensive stocking of hatchery fish throughout Japan, indigenous populations of O. m. ishikawae are now on the verge of extinction. We examined the genetic effects of stocking hatchery fish on wild populations in the
River Koza, Japan, using microsatellite and mitochondrial DNA (mtDNA) markers. For mtDNA, haplotype mt1, which is common in
wild populations, was present exclusively in isolated wild populations assumed to be unaffected by previous stocking, while
it was never observed in hatchery fish. Genetic diversity was much higher in wild populations in the stocked area, which shared
many mtDNA haplotypes with hatchery fish, than in isolated wild populations with haplotype mt1. Pairwise F
ST estimates based on microsatellites showed significant differentiation among the isolated populations with many microsatellite
loci monomorphic. Significant deviation from Hardy–Weinberg equilibrium was observed in wild populations in the area subject
to stocking, where a Bayesian-based assignment test showed a high level of introgression with hatchery fish. These results
suggest that wild populations with haplotype mt1, which became isolated through anthropogenic environmental change in the
1950–1960s, represent indigenous populations of O. m. ishikawae in the River Koza. They have low genetic diversity, most likely caused by genetic bottlenecks following damming and environmental
deterioration, while stocking of hatchery fish over the past 30 years apparently had a large impact on the genetic structure
of wild populations in the main channel of the River Koza. 相似文献
2.
In order to clarify the origin and genetic diversity of indigenous cattle breeds in China, we carried out phylogenetic analysis
of representatives of those breeds by employing mitochondrial gene polymorphism. Complete cyt b gene sequences, 1140 bp in length, were determined for a total of 136 individuals from 18 different breeds and these sequences
were clustered into two distinct genetic lineages: taurine (Bos taurus) and zebu (Bos indicus). In analysis of the cyt b gene diversity, Chinese cattle showed higher nucleotide (0.00923) and haplotype diversity (0.848) than the reports from other
studies, and the animals from the taurine lineage indicated higher nucleotide diversity (0.00330) and haplotype diversity
(0.746) than the ones from the zebu lineage (0.00136; 0.661). The zebu mtDNA dominated in the southern breeds (63.3–100%),
while the taurine dominated in the northern breeds (81.8–100%). Six cattle breeds from the central area of China exhibited
intermediate frequencies of zebu mtDNA (25–71.4%). This polymorphism revealed a declining south-to-north gradient of female
zebu introgression and a geographical hybrid zone of Bos taurus and Bos indicus in China. 相似文献
3.
Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered tree in eastern China. Habitat destruction has resulted in fragmentation of remnant populations
and extinction of local populations. AFLP and cpDNA markers were used to determine the population structure of remnant populations
of B. wilsonii var. pubipetiolata. Moderate nuclear genomic diversity was found within each of the four remnant populations (H
S = 0.141–0.172), while the cpDNA haplotype diversity in each population ranged from 0.356 to 0.681. Six haplotypes were identified
by a combined cpRFLP and cpSSR analysis in a total of 89 individuals. AMOVA revealed significantly AFLP genetic differentiation
within and between regions (ΦSC = 0.196, ΦCT = 0.396, respectively), and a high cpDNA haplotype differentiation between regions (ΦCT = 0.849). The results suggest low gene flow between populations of B. wilsonii var. pubipetiolata. Strong genetic divergence between two regional populations as revealed by both AFLP and cpDNA markers provided convincing
evidence that two distinct evolutionary lineages existed, and should be recognized as ‘evolutionary significant units’ (ESUs)
for conservation concerns. 相似文献
4.
5.
Of the only known two Lagoon populations of Irrawaddy dolphins (Orcaella) in the world, one is residing in the Chilika Lagoon in Orissa state, India. In addition to accidental deaths in gill net
fishery and mechanized boat operations, there has been exploitation of the species for their oil. Extreme patchy distribution
and vulnerability to becoming entangled in fishing gear has made it a focus of conservation concern. Information on genetic
diversity of populations has considerable potential for informing conservation plans. The present paper reports the first
genetic study of O. brevirostris from Chilika Lagoon based on mtDNA sequencing and PCR-based sex identification from 11 individuals. Control region sequence
comparison showed two haplotypes and cytochrome b a single haplotype in the Chilika population of the species. Phylogenetic analysis indicated distinct clades within the Asian
samples, with the Indian population showing closest genetic proximity to the haplotypes from Thailand. Sex of the animal was
determined by PCR-based method. It is important to continue to examine the population discreteness and genetic variation of
Irrawaddy dolphin in Chilika Lagoon vis-à-vis its global geographic distribution for formulating the conservation plans of
the species. 相似文献
6.
B. A. Malyarchuk M. V. Derenko D. I. Berman T. Grzybowski N. A. Bulakhova A. P. Kryukov A. N. Lejrikh 《Molecular Biology》2009,43(1):47-54
The nucleotide sequence variation of the mitochondrial cytochrome b gene was studied in Schrenck newt Salamandrella schrenckii (Strauch, 1870) from populations of Primorye and the Khabarovsk region. Phylogenetic analysis revealed two haplotype clusters, southern cluster 1 and northern cluster 2, with a divergence of 3%. Analysis of the mtDNA and cytochrome b amino acid sequence variations made it possible to assume that the modern range of Schrenck newt was colonized from south Primorye northwards. In contrast to the southern cluster, the northern one demonstrated all the signs of demographic expansion (a unimodal distribution of pairwise nucleotide differences, specific results of tests for selective neutrality of mtDNA variation, and a good correspondence of genetic parameters to those expected from demographic expansion models). 相似文献
7.
Marjan Khalili Mahani Nobuyuki Inomata Alireza Saboori Baraldin Ebrahim Sayed Tabatabaei Hiroko Ishiyama Ardeshir Ariana Alfred E. Szmidt 《Experimental & applied acarology》2009,48(4):273-289
Allothrombium
pulvinum Ewing is a common natural enemy of aphids and some other arthropods. So far, there are no studies that have addressed genetic
variation of this predatory mite. We investigated genetic variation of A. pulvinum across its whole known range in Iran. A 410 bp portion of the mitochondrial cytochrome c oxidase subunit I gene (coxI) and 797–802 bp portion of the internal transcribed spacer 2 of rDNA (ITS2) were sequenced for 55 individuals from 11 populations, resulting in 12 and 26 haplotypes, respectively. In the coxI region, haplotype and nucleotide diversities varied among populations from 0.00 to 0.90 and from 0.0000 to 0.0110, respectively.
In the ITS2 region they varied from 0.20 to 0.91 and from 0.0006 to 0.0023, respectively. For both gene regions the highest haplotype
and nucleotide diversities were detected in population Mahmoud Abad from northern Iran. Statistically significant population
differentiation (F
ST) was detected in most pair-wise population comparisons. The results of population differentiation for both gene regions were
generally congruent indicating that A. pulvinum from Iran consists of genetically different populations. This suggests that A. pulvinum comprises at least two geographically distinct populations or even more than one species. This study is an initial step towards
understanding genetic variation of A. pulvinum, a taxon for which little molecular information is available. More intensive sampling and analysis of additional DNA regions
are necessary for more detailed classification of this taxon. 相似文献
8.
Two small cyprinid fishes, Hemigrammocypris rasborella and Pseudorasbora pumila subsp. (sensu Nakamura 1963), inhabit similar habitats and often occur sympatrically in the Ise Bay basin, central Honshu
Island, Japan. Their genetic population structures were revealed, using sequence data from the mitochondrial cytochrome b gene, and then compared. Hemigrammocypris rasborella populations in the Ise Bay area formed a monophyletic group that has been isolated from eastern (Tenryu River) and western
(Lake Biwa–Yodo River) populations at least for several hundred thousand years. Pseudorasbora pumila subsp., endemic to the Ise Bay area, was estimated to have become isolated from its sister subspecies, P. p. pumila, about 5 million years ago. Both H. rasborella and P. pumila subsp. had centers of genetic diversity around the Okazaki Plain in the eastern part of the basin and showed trans-bay distribution
of haplotypes or haplotype groups. Their common population structure was explained by geological features in the Ise Bay area,
in which a large paleo-river system developed in regression periods, suggesting gene flow among populations of each species
in the mid to lower reaches of the paleo-river. Based on the estimated expansion or divergence time, however, not all populations
experienced gene flow during the Last Glacial. In contrast to the maintenance of high genetic diversity in H. rasborella, almost all populations of P. pumila subsp. have lost mitochondrial DNA genetic diversity. This implies that effective population size of P. pumila subsp. tended to be smaller, probably because of differences in reproductive ecology, even though the two species have been
exposed to similar environmental changes. For conservation of the two species, genetic and adaptive differentiation among
local populations should be considered, and attention should be paid to inbreeding depression, especially in P. pumila subsp.
An erratum to this article can be found at 相似文献
9.
The rapidly declining Golden-winged Warbler (Vermivora chrysoptera) is of conservation concern owing in part to hybridization with the closely related Blue-winged Warbler (V. pinus). These species hybridize extensively in eastern North America and over the past century the Blue-winged Warbler has displaced
the Golden-winged Warbler from substantial regions of its historic breeding range. A previous study suggested that these genetic
interactions result in rapid and asymmetric introgression of Blue-winged Warbler mitochondrial DNA (mtDNA) into Golden-winged
phenotype populations within the zones of contact, but more recent and extensive surveys have documented a more complex pattern
of genetic interchange between these taxa. We surveyed mtDNA/phenotype associations in 104 individuals of known phenotype
drawn from two locations with different histories of contact and found substantial variation between sites in the extent of
introgression. Where both species have co-existed for more than a century, we found evidence of bi-directional introgression
and the long-term persistence of Golden-winged mtDNA haplotypes. At the leading edge of the northward expansion of Blue-winged
Warblers, we found predominantly Golden-winged Warbler mtDNA haplotypes in both Golden-winged and hybrid-phenotype individuals.
Across both sites, genetic swamping does not appear to be occurring via the early immigration of Blue-winged Warbler females
into populations dominated by Golden-winged Warbler phenotypes. Instead, the differing patterns of mitochondrial introgression
may be driven by the relative local population sizes of the parental species coupled with subtle between-species differences
in mate choice and habitat preferences. 相似文献
10.
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
11.
Cupressus chenggiana S. Y. Hu (Cupressaceae) is an endemic and endangered conifer species in southwest China. In order to study the population
genetics and design the effective conservation methods, we aimed to develop microsatellite primers for this species in the
present study. We developed eight new microsatellite loci for this species through biotin capture method. Polymorphism of
each locus was further assessed in 18 individuals from three geographically distant populations. The number of alleles per
locus ranged from 6 to 11 with an average of 8.13. The observed and expected heterozygosities ranged from 0.219 to 0.296 and
from 0.374 to 0.470, with averages of 0.254 and 0.417, respectively. We further found that three of nine microsatellite loci
developed previously for another congeneric species showed polymorphic banding patters. We performed primer-crossing tests
of these loci in the other two congeneric species which are closely related to C. chenggiana (C. gigantea and C. duclouxiana). These microsatellite markers would be effective for analyzing genetic diversity and population genetic structure of this
species and its morphological differentiation with the close relatives. 相似文献
12.
Eastern and Western Gambusia (i.e., Gambusia holbrooki and G. affinis, respectively) are considered together here because these two fish species are very closely related, similar in appearance,
similar in biology and often confused. Widely divergent attitudes have developed with regard to these fish with some viewing
them as being highly beneficial to humans through controlling mosquitoes and the diseases they harbor, and others expressing
concern about the negative impacts that these fish may have on other species with which they interact. Because of the widespread
distribution, high levels of abundance, ease of capture and captive maintenance, and divergent attitudes, a very large and
diffuse literature has developed with regard to these species. In fact, few fish species have been studied as much as or more
than these two species combined. There has, however, been no comprehensive review of their biology published to date. As it
is not possible to provide a comprehensive review of Gambusia biology in one reasonably sized document, I provide here a review of aspects of their biology at the level of species and
individual. In another review I focused instead on the levels of population and species communities and consider the impacts
that these fish have on mosquitoes and other organisms (Pyke, unpublished). As would be expected of such widespread and abundant
species, Gambusia affinis and G. holbrooki are clearly very tolerant, adaptable and variable in their biology, at both an individual and population level. Both individuals
and populations can tolerate, and often thrive within, a wide range of conditions and the abilities of individuals to do this
are enhanced if they have time to acclimate to any changes. Populations can adapt through genetic or evolutionary changes
in response to conditions that vary in space or time, and there is significant genetic variation within and between populations. 相似文献
13.
Guillermo Velo-Antón Mario García-París Adolfo Cordero Rivera 《Conservation Genetics》2008,9(5):1263-1274
The European pond turtle (Emys orbicularis) is threatened and in decline in several regions of its natural range, due to habitat loss combined with population fragmentation.
In this work, we have focused our efforts on studying the genetic diversity and structure of Iberian populations with a fine-scale
sampling (254 turtles in 10 populations) and a representation from North Africa and Balearic island populations. Using both
nuclear and mitochondrial markers (seven microsatellites, ∼1048 bp nDNA and ∼1500 bp mtDNA) we have carried out phylogenetic
and demographic analyses. Our results show low values of genetic diversity at the mitochondrial level although our microsatellite
dataset revealed relatively high levels of genetic variability with a latitudinal genetic trend decreasing from southern to
northern populations. A moderate degree of genetic differentiation was estimated for Iberian populations (genetic distances,
F
ST
values and clusters in the Bayesian analysis). The results in this study combining mtDNA and nDNA, provide the most comprehensive
population genetic data for E. orbicularis in the Iberian Peninsula. Our results suggest that Iberian populations within the Iberian–Moroccan lineage should be considered
as a single subspecies with five management units, and emphasize the importance of habitat management rather than population
reinforcement (i.e. captive breeding and reintroduction) in this long-lived species. 相似文献
14.
The small group of resurrection plants is a unique model which could help us in further understanding of abiotic stress tolerance. The most frequently used approach for investigations on gene functions in plant systems is genetic transformation. In this respect, the establishment of in vitro systems for regeneration and micro propagation is necessary. On the other hand, in vitro cultures of such rare plants could preserve their natural populations. Here, we present our procedure for in vitro regeneration and propagation of Haberlea rhodopensis – a resurrection plant species, endemic for the Balkan region. 相似文献
15.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
16.
Bryophytes seem particularly suitable to investigate genetic diversity in relation to habitat disturbance due to their large
employment as bioindicators and to the recent application of molecular markers to moss population studies. Genetic variation
and structure were analysed in seven urban, extraurban and remote populations of Leptodon smithii, an epiphytic moss of Quercus ilex, a phanerogamic species of Mediterranean climax vegetation. A total of 210 individual shoots were DNA extracted and amplified
with internal simple sequence repeat (ISSR) primers, and 54 haplotypes were identified. An uneven distribution of haplotype
number and frequencies was observed among sites, with a higher number of haplotypes and more homogeneous haplotype frequencies
in the extraurban/remote populations. Molecular diversity indices were overall higher in the extraurban sites than in the
urban ones. Multilocus linkage disequilibrium values were in line with the occurrence of sexual/asexual reproduction in the
seven populations. The isolation-by-distance model was not supported by Mantel test among sites; however, within-population
fixation index (FST) highlighted a clear relation between genetic and physic distances among trees, suggesting a limited dispersal range for
L. smithii’s spores. The genetic structure was mainly affected by population size, wood structure and extent, and genetic drift consequent
to habitat fragmentation and human-induced disturbance. 相似文献
17.
A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan 相似文献
18.
19.
Takaaki Shimizu 《Ichthyological Research》2008,55(2):101-111
Mitochondrial DNA divergence among populations of the Japanese spinous loach Cobitis shikokuensis, endemic to Shikoku Island, was investigated by restricted fragment length polymorphism analysis. A total of 68 restriction
sites on DNA fragments from the cytochrome b to D-loop regions and from the 12S rRNA to 16S rRNA regions, amplified by PCR, were analyzed. A total of 12 haplotypes (plus
6 in outgroups) were detected in 268 specimens collected from 19 localities in seven rivers (and 41 specimens from four localities
in three rivers in outgroups). Three of the seven river populations of C. shikokuensis were shown to have unique haplotypes, and four of the seven river populations were monomorphic. The nested structure of the
haplotype network for populations of C. shikokuensis exhibited two large clades corresponding to (1) populations from the Shimanto River and its neighbors and (2) two genetically
divergent populations in the Shigenobu and Iwamatsu Rivers. The population from the Shimanto River, the largest river inhabited
by C. shikokuensis, maintains great haplotype diversity as well as the allozyme diversity previously reported. On the other hand, populations
from the Hiji River, the second largest river, which exhibited the highest allozyme diversity, were monomorphic in their mtDNA.
The nested clade analysis (NCA) revealed that past fragmentation between the above two clades could occur in the initial distribution
process of C. shikokuensis. The large genetic divergence of two river populations from the Shigenobu and Iwamatsu Rivers was inferred to be caused by
a process of long distance colonization and fragmentation. MtDNA introgression into the Hiji River population from southern
river populations was suggested. Taking genetic divergence into consideration, each river population of C. shikokuensis should be conserved separately as like a distinct species, and conservation programs for the small populations showing less
genetic variability should be invoked as soon as possible. 相似文献
20.
Li Yan Dengqiang Wang Yaoling Fang Shaoping Liu Xinbing Duan Yonghua Chang Daqing Chen 《Environmental Biology of Fishes》2008,82(1):35-40
The bronze gudgeon, Coreius heterodon (Bleeker), is an economically important species, which only inhabits the Yangtze River. The stock declined drastically in
recent years due to dam construction, over-fishing, and pollution. Little is known about its population genetic structure.
In this study, the sequences of the mitochondrial DNA (mtDNA) control regions of natural bronze gudgeon was determined for
fish collected from four sites in the Yangtze River (n = 102). The molecular data were used to estimate the genetic diversity and differentiation of the bronze gudgeon. The results
showed that 28 haplotypes and 22 variable sites were found, and the haplotype diversity (π) and nucleotide diversity (h) were 0.849 and 0.00257, respectively. A low level of genetic diversity exists in the bronze gudgeon. Analysis of molecular
variance (AMOVA) suggests that 98.8% of the genetic variability occurred within the populations; the site of collection had
little influence on diversity. Future research should focus on investigating the genetic divergence of populations in different
tributaries and using additional polymorphic markers, such as microsatellite DNA, to verify the results and improve interpretation. 相似文献