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1.
Conserving endangered wild rice species requires a thorough understanding of their population genetic structure and appropriate approaches. We applied six and seven microsatellite loci to study the genetic structure of six populations throughout the range of Chinese Oryza rufipogon and Oryza officinalis, respectively. The results showed that O. rufipogon possesses higher levels of genetic diversity but lower differentiation (RS = 3.2713, P = 100.0%, HO = 0.1401, HS = 0.5800, FST = 0.271) than O. officinalis (RS = 2.0545, P = 57.14%, HO = 0.0470, HS = 0.2830, FST = 0.554). Mean population FIS was slightly larger for O. officinalis (FIS = 0.844) than that for O. rufipogon (FIS = 0.755), indicating that O. officinalis has slightly higher departures from Hardy–Weinberg expectations and heterozygosity deficits than O. rufipogon. In addition to different origins and evolutionary histories, O. officinalis has restricted gene flow, high inbreeding, isolated small populations and fewer opportunities of hybridization with other taxa, which may determine major differences in population genetic structure from O. rufipogon. Our results suggest the adoption of a plan of involving fewer populations but more individuals within populations for O. rufipogon, while both the number of populations and the individuals for a sampled population should be almost equally considered for O. officinalis. The known high degree of inbreeding in the populations of both species implies that conservation and restoration genetics should particularly focus on the maintenance of historically significant processes such as high levels of outbreeding, gene flow and large effective population sizes. We finally proposed to further estimate the role of rice gene flow in the conservation of O. rufipogon, and to perform detailed analysis of mating systems in both species for better conservation perspectives of their ecological and evolutionary processes. 相似文献
2.
Cypripedium macranthos var. rebunense is an endangered plant endemic to Rebun Island, Japan. A proper understanding of genetic diversity is needed when conducting
conservation programs for rare and endangered species. We therefore examined the genetic diversity of C. macranthos var. rebunense using allozyme markers with a view to future conservation. Our study revealed that C. macranthos var. rebunense has relatively high genetic diversity (P was 0.62, n
a and n
e were 1.85 and 1.28 respectively, and H
o and H
e were 0.163 and 0.187, respectively) when compared with other plant taxa. The natural habitats of C. macranthos var. rebunense are geographically separated into northern and the southern populations. Disappearance of alleles and increase in homozygosity
expected as a result of the bottleneck effect were observed, particularly in the southern populations composed of a small
number of plants. As additional negative effects (inbreeding depression and further genetic drift) due to fragmentation are
predicted in these populations, the southern populations may show deterioration of genetic diversity in the near future. 相似文献
3.
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
4.
Patrícia J. Faria Neiva M. R. Guedes Carlos Yamashita Paulo Martuscelli Cristina Y. Miyaki 《Biodiversity and Conservation》2008,17(4):765-779
The Hyacinth Macaw (Anodorhynchus hyacinthinus) is one of 14 endangered species in the family Psittacidae occurring in Brazil, with an estimated total population of 6,500
specimens. We used nuclear molecular markers (single locus minisatellites and microsatellites) and 472 bp of the mitochondrial
DNA control region to characterize levels of genetic variability in this species and to assess the degree of gene flow among
three nesting sites in Brazil (Pantanal do Abobral, Pantanal de Miranda and Piauí). The origin of five apprehended specimens
was also investigated. The results suggest that, in comparison to other species of parrots, Hyacinth Macaws possess relatively
lower genetic variation and that individuals from two different localities within the Pantanal (Abobral and Miranda) belong
to a unique interbreeding population and are genetically distinct at nuclear level from birds from the state of Piauí. The
analyses of the five apprehended birds suggest that the Pantanal is not the source of birds for illegal trade, but their precise
origin could not be assigned. The low genetic variability detected in the Hyacinth Macaw does not seem to pose a threat to
the survival of this species. Nevertheless, habitat destruction and nest poaching are the most important factors negatively
affecting their populations in the wild. The observed genetic structure emphasizes the need of protection of Hyacinth Macaws
from different regions in order to maintain the genetic diversity of this species. 相似文献
5.
Heparan sulfate proteoglycans play a vital role in signaling of various growth factors in both Drosophila and vertebrates. In Drosophila, mutations in the tout
velu (ttv) gene, a homolog of the mammalian EXT1 tumor suppressor gene, leads to abrogation of glycosaminoglycan (GAG) biosynthesis. This impairs distribution and signaling
activities of various morphogens such as Hedgehog (Hh), Wingless (Wg), and Decapentaplegic (Dpp). Mutations in members of
the exostosin (EXT) gene family lead to hereditary multiple exostosis in humans leading to bone outgrowths and tumors. In this study, we provide
genetic and biochemical evidence that the human EXT1 (hEXT1) gene is conserved through species and can functionally complement the ttv mutation in Drosophila. The hEXT1 gene was able to rescue a ttv null mutant to adulthood and restore GAG biosynthesis. 相似文献
6.
We examined the genetic population structure of Lefua echigonia (Japanese name, hotoke-dojo) using polymerase chain reaction restriction-fragment length polymorphisms (PCR-RFLPs) of the mitochondrial cytochrome b gene and two allozymic loci. The phylogenetic relationships of L. echigonia and those among L. echigonia, Lefua sp. (nagare hotoke-dojo), and L. nikkonis (ezo hotoke-dojo) were also investigated based on the nucleotide sequences of the cytochrome b gene. PCR-RFLP analysis revealed 18 mitotypes in L. echigonia, 2 in Lefua sp., and 1 in L. nikkonis. Phylogenetic trees based on the cytochrome b sequences indicated that the 18 mitotypes in L. echigonia were divided into five distinct groups (South-Kanto, North-Kanto, Tohoku, Echigo, and Tokai-Kinki clades) that differed by 8.5–15.3%, reflecting region-specific geographic distributions. The distributions of alleles in two allozymic loci roughly corresponded to those of the mitotype groups. The divergence times of the five groups were estimated to be about 3.4–7.7 million years ago by applying a general rate for mitochondrial DNA, suggesting that the divergence among them might have occurred in the late Tertiary. It can be inferred that the regional differentiation of each group was mainly due to geographic isolation and that this has been maintained, because the boundaries among the groups corresponded to geological features. The trees also supported the existence of three taxa, L. echigonia, Lefua sp., and L. nikkonis. We concluded that Lefua sp. was distinguished from other species in Lefua by morphological and ecological characters and also by genetic divergences of the cytochrome b gene. Our study also demonstrated the superior efficacy and simplicity of PCR-RFLP analysis as a method for detecting genetic variation in L. echigonia. 相似文献
7.
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
8.
The microtubule-binding protein tau has been investigated for its contribution to various neurodegenerative disorders. However,
the findings from transgenic studies, using the same tau transgene, vary widely among different laboratories. Here, we have investigated the potential mechanisms underlying tauopathies
by comparing Drosophila (d-tau) and human (h-tau) tau in a Drosophila model. Overexpression of a single copy of either tau isoform in the retina results in a similar rough eye phenotype. However, co-expression of Par-1 with d-tau leads to lethality, whereas co-expression of Par-1 with h-tau has little effect on the rough eye phenotype. We have found analogous results by comparing larval proteomes. Through genetic
screening and proteomic analysis, we have identified some important potential modifiers and tau-associated proteins. These
results suggest that the two tau genes differ significantly. This comparison between species-specific isoforms may help to clarify whether the homologous
tau genes are conserved.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
This study was supported by the National Science Foundation of China (30270341; 30630028), the Multidisciplinary Program (Brain
and Mind) of the Chinese Academy of Sciences, the Major State Basic Research Program (“973 program”; G2000077800; G2006CB806600;
2006CB911003), the Precedent Project of Important Intersectional Disciplines in the Knowledge Innovation Engineering of the
Chinese Academy of Sciences (KJCX1-09-03). 相似文献
9.
Most of our current understanding of comparative population structure has been come from studies of parasite–host systems,
whereas the genetic comparison of gallnut-aphids and their host-plants remain poorly documented. Here, we examined the population
genetic structure of the Chinese sumac aphid Schlechtendalia chinensis and its unique primary host-plant Rhus chinensis in a mountainous province in western China using inter-simple sequence repeat (ISSR) markers. Despite being sampled from
a mountainous geographic range, analysis of molecular variance (AMOVA) showed that the majority of genetic variation occurred
among individuals within populations of both the aphid and its host. The aphid populations were found to be structured similarly
to their primary host populations (F
ST values were 0.239 for the aphid and 0.209 for its host), suggesting that there are similar patterns of gene flow between
the populations of the aphid and between populations of its host-plant. The genetic distances (F
ST/1 − F
ST) between the aphid populations and between its host-plant populations were uncorrelated, indicating that sites with genetically
similar host-plant populations may not always have genetically similar aphid populations. The lack of relationships between
genetic and geographical distance matrices suggested that isolation by distance (IBD) played a negligible role at this level.
This may be mainly attributed to the founder effect, genetic drift and the relative small spatial scale between populations.
Zhumei Ren and Bin Zhu contributed equally to this work. 相似文献
10.
11.
Vesna Milankov Gunilla Ståhls Jelena Stamenković Ante Vujić 《Conservation Genetics》2008,9(5):1125-1137
The genetic structure of 10 populations of the Merodon aureus group from the Balkan Peninsula was examined through allozyme electrophoresis and mitochondrial DNA sequencing of the cytochrome
c oxidase subunit I (COI). Six diagnosable cryptic taxa were identified within the morphologically defined species M. aureus Fabricius, 1805 and M. cinereus (Fabricius, 1794), with clear separation of the populations (((M. aureus A + M. aureus B) + cinereus complex) + M. aureus C). The parsimony analysis of COI sequence data of the aureus–cinereus complex using Merodon avidus A species as an outgroup resulted in two main clades, (M. aureus A + M. aureus B) and ((M. aureus C + M. cinereus B + M. cinereus C) + M. cinereus A), which differed on average by 5.7%. The observed spatial distribution of the taxonomic diversity of the group suggested
that these taxa originated from a common ancestral population in the Mediterranean. Identification of genetic uniqueness and
genetic endemism emphasizes the importance of molecular markers and estimation of genetic diversity in recognition of conservation
units. The primary goals of the conservation measures that we propose are the protection of phylogenetic lineages within the
highly diverse M. aureus group taxa and conservation of the genetic variation through management of important areas. 相似文献
12.
Biological invasions offer excellent systems to study the evolutionary processes involved in introductions of species to new
ranges. Molecular markers can reveal invasion histories and the effects of introductions on amounts and structuring of genetic
variation. We used five polymorphic microsatellite loci to elucidate genetic diversity and population structure between native
range and introduced range populations of a prominent North American rangeland weed, Centaurea diffusa (Asteraceae). We found that the total number of alleles and the number of private alleles was slightly higher in the native
Eurasian range, and that allelic richness did not differ between the ranges, indicating overall levels of diversity were similar
in Eurasia and North America. It therefore seems unlikely that this invasion has been affected by genetic bottlenecks or founder
effects. Indeed, results of assignment tests suggest that multiple introductions have contributed to North America’s C. diffusa invasion. Additionally, assignment tests show that both Eurasian and North American sites had a strong pattern of mixed genetic
ancestry. This mixed assignment corresponded to a lack of geographic population structure among Eurasian samples. The lack
of population structure in the native range conflicts with general expectations and findings to date for invasion genetics,
and cautions that even species’ native ranges may show signs of recent ecological upheaval. Despite the mixed assignments,
North American samples showed strong population structure, suggesting that the invasion has been characterized by long-range
dispersal of genetically distinct propagules across the introduced range. 相似文献
13.
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
14.
15.
Yoshiaki Tsuda Madoka Kimura Shuri Kato Toshio Katsuki Yuzuru Mukai Yoshihiko Tsumura 《Journal of plant research》2009,122(4):367-375
The genetic resources of a particular species of flowering cherry, Cerasus jamasakura, have high conservation priority because of its cultural, ecological and economic value in Japan. Therefore, the genetic
structures of 12 natural populations of C. jamasakura were assessed using ten nuclear SSR loci. The population differentiation was relatively low (F
ST, 0.043), reflecting long-distance dispersal of seeds by animals and historical human activities. However, a neighbor-joining
tree derived from the acquired data, spatial analysis of molecular variance and STRUCTURE analysis revealed that the populations
could be divided into two groups: one located on Kyusyu Island and one on Honshu Island. Genetic diversity parameters such
as allelic richness and gene diversity were significantly lower in the Kyushu group than the Honshu group. Furthermore, STRUCTURE
analysis revealed that the two lineages were admixed in the western part of Honshu Island. Thus, although the phylogeographical
structure of the species and hybridization dynamics among related species need to be evaluated in detail using several marker
systems, the Kyusyu Island and Honshu Island populations should be considered as different conservation units, and the islands
should be regarded as distinct seed transfer zones for C. jamasakura, especially when rapid assessments are required. 相似文献
16.
Na Chen Yan-Zhuo Yang Xiao-li Yang Xing-xu Zhang Chun-jie Li 《Conservation Genetics》2008,9(4):961-963
Microsatellites are often highly variable and abundant in most complex genomes, therefore are widely used in population genetic
studies. In this study, twelve polymorphic microsatellite loci were isolated and characterized for the Achnatherum inebrians, a plant abundant in grasslands of Northwest China. Characterization of 24 A. inebrians individuals form four geographically distant populations (Gansu, Qinghai, Xinjiang and Inner Mongolia provinces) showed moderate
to high allelic diversity ranging from 3 to 13 alleles per locus, and the expected heterozygosity ranging from 0.41 to 0.67.
No evidence of linkage disequilibrium was found for any locus pairwise comparisons. The markers described here will be useful
for investigating the genetic diversity, genetic structure and gene flow of this species.
Na Chen and Yan-Zhuo Yang contributed equally to this work. 相似文献
17.
Rauquírio Marinho da Costa Luci Cajueiro Carneiro Pereira Felipe Fernández 《Hydrobiologia》2008,605(1):55-63
Coenagrionid damselflies are in general decline in the British Isles. Numerous factors have been implicated in the loss of
these species including recent speculation that hybridisation between congeners may result in species decline. Here we use
a panel of 12 microsatellite loci to examine levels of genetic divergence and the likely occurrence of hybridisation in five
populations of Coenagrion puella and C. pulchellum using samples from four sites in south-east England. Coenagrion puella and C. pulchellum were highly genetically divergent, and there was no evidence of hybridisation between any of the populations examined, even
where C. puella and C. pulchellum were sympatric. There was some suggestion that C. pulchellum was less genetically diverse than C. puella, though this may have been a result of ascertainment bias associated with cross-species application of microsatellite markers.
We conclude that there is no evidence that hybridisation between C. puella/pulchellum could be responsible for the on-going demographic decline in C. pulchellum. Nevertheless, further genetic studies such as this one are likely to provide estimates of diversity, population structure
and dispersal capacity that will be invaluable in future conservation management strategies for coenagrionid damselflies.
Handling editor: S. Wellekens 相似文献
18.
In vitro propagation of Rhododendron ponticum L. subsp. baeticum, an endangered species present in limited and vulnerable populations as a Tertiary relict in the southern Iberian Peninsula, was attained. Several cytokinin:IAA ratios and a range of zeatin concentrations were evaluated for their effect on shoot multiplication from apical shoots and nodal segments. The type of cytokinin and the origin of the explant were the most important factors affecting shoot multiplication. The highest shoot multiplication rate was obtained from single-nodal explants on medium supplemented with zeatin. Increasing zeatin concentration promotes shoot multiplication independently of explant type, although this effect tends to decrease with higher zeatin concentration. Shoot growth was higher in apical shoots and it was not stimulated by the presence of auxin. A number of experiments were conducted to identify suitable procedures for rooting of in vitro produced shoots. The best results in terms of in vitro rooting were obtained with Andersons modified medium with macrosalts reduced to one-half, regardless of the auxin or its concentration in the medium. Although rooting frequency rose to 97% by basal immersion of shoots in auxin concentrated solution followed by in vitro culture on an auxin-free medium, the survival of the plants after 6 months of acclimatization was poor (50%). Best results (100% rooting and survival) were observed for ex vitro rooting. The micropropagated plants from this study were successfully reintroduced into their natural habitat (87% of survival after 8 months). 相似文献
19.
Seishi Kimura Daniel Golani Yukio Iwatsuki Motohiko Tabuchi Tetsuo Yoshino 《Ichthyological Research》2007,54(2):145-159
The Indo-Pacific marine atherinid fishes Atherinomorus forskalii (Rüppell, 1838), Atherinomorus lacunosus (Forster, 1801), and Atherinomorus pinguis (Lacepède, 1803) are redescribed as valid species based on the types and non-type specimens collected throughout the Indo-Pacific.
They are similar to each other chiefly in having a wide midlateral band (almost the same or greater than the midlateral scale
width), large mouth (posterior tip of upper jaw reaching to or beyond a vertical through anterior margin of pupil), and no
distinct tubercle at the posterior end of the dentary. All three species are distinguishable from congeners by those characters.
The three species have long been confused with each other or synonymized erroneously as a single species. Atherinomorus forskalii, known from the Red Sea and eastern Mediterranean, differs from Atherinomorus lacunosus and Atherinomorus pinguis in having conspicuous, large endopterygoid teeth, forming obvious tooth ridges. Atherinomorus lacunosus, widely distributed in almost the entire Indo-Pacific, from East Africa to Tonga, north to southern Japan, and south to northern
Australia, differs from Atherinomorus pinguis in having a wider midlateral band (the lower margin reaching to almost the center of the fourth scale row at level of the
anal fin origin vs. the lower margin reaching to the ventral end of the third scale row in Atherinomorus pinguis) and more numerous midlateral scales (40–44 vs. 38–41 in Atherinomorus pinguis). Atherina morrisi Jordan and Starks, 1906, Hepsetia pinguis mineri Nichols and Roemhild, 1951, Pranesus capricornensis Woodland, 1961, Pranesus maculatus Taylor, 1964, and Pranesus pinguis ruppelli Smith, 1965, are regarded as junior synonyms of Atherinomorus lacunosus. Atherinomorus pinguis is also widely distributed in the Indo-West Pacific, from East Africa to northern Australia and north to southern Japan.
Atherina pectoralis Valenciennes, 1835, is considered a junior synonym of Atherinomorus pinguis.
Supplementary material to this paper is available in electronic format at 相似文献
20.
Ghaiet M. Hajji F. Charfi-Cheikrouha Rita Lorenzini Jean-Denis Vigne Günther B. Hartl Frank E. Zachos 《Biodiversity and Conservation》2008,17(3):659-673
Red deer (n = 149) from eight geographical locations, including the endangered endemic populations from the Tyrrhenian islands (Sardinia and Corsica), were analysed at eight polymorphic microsatellite loci. Two questions were addressed: (1) Is there a founder effect in the Corsican population, which was reintroduced to the island using Sardinian deer after the species’ extinction on Corsica? (2) What is the origin of the Tyrrhenian or Corsican red deer (Cervus elaphus corsicanus)? Our results showed signs of a founder effect for the red deer on Corsica in that these deer showed differentiation from the Sardinian population as measured by FST values, assignment tests (with and without a priori definition of populations) and individual-based dendrograms. Genetic variability, however, did not differ significantly between the two populations. With respect to the phylogeography of C. e. corsicanus we found that both deer from North-Africa and Mesola on the Italian mainland were genetically close to the Corsican red deer, but phylogenetic trees based on genetic distances were only poorly supported statistically. Among all populations studied the Mesola red deer showed the lowest distance values from Corsican red deer and yielded allele frequencies that were more similar to those of C. e. corsicanus than were those of North-African red deer. These results are in line with recent palaeontological and archaeozoological findings which suggest that the Corsican red deer is derived from small Italian red deer introduced from the mainland to Sardinia and Corsica during the Late Neolithic and just before the beginning of Classical Antiquity, respectively. They also suggest a possible recent introduction of Tyrrhenian red deer to North-Africa (rather than the other way around), thus accounting for the close genetic relationship (especially based on mitochondrial DNA) that has repeatedly been found between C. e. corsicanus and C. e. barbarus. 相似文献