An investigation of the possible causes for the loss of productivity in genetically improved farmed tilapia strain in Fiji: inbreeding versus wild stock introgression     

Elise M McKinna  Satya Nandlal  Peter B Mather  David A Hurwood 《Aquaculture Research》2010,41(11):e730-e742

Four microsatellite markers and a mitochondrial DNA (mtDNA) fragment were used to investigate two possible explanations for a reported decline in productivity of genetically improved farmed tilapia (GIFT) in Fiji: (i) a decline in genetic diversity (GD) and (ii) genetic introgression from feral tilapia populations. Genetic diversity was estimated using θ and allelic richness, while Bayesian clustering was used to assign individuals to genetic groups (K=2 or 3) to test for introgression. Differentiation among groups was estimated using F_ST analysis. Results indicate that genetic diversity had declined compared with a GIFT reference stock from WorldFish Centre, while there was little evidence for introgression from feral tilapia populations. Loss of genetic diversity most probably resulted from practices that have not actively managed genetic resources in the hatchery. While GIFT is considered to be an improved line of Nile tilapia (Oreochromis niloticus), mtDNA analysis here revealed haplotypes assigned previously to three discrete Oreochromis species (O. niloticus, Oreochromis mossambicus and Oreochromis aureus) in both the Fijian strain and the WorldFish Centre strain. Possible sources for the three divergent lineages are discussed. Results have implications for the management and future expansion of the tilapia culture industry in Fiji as well as in other Pacific island nations.  相似文献   

Genetic diversity and population structure of burbot Lota lota in Germany: Implications for conservation and management     

Maj Wetjen  Thomas Schmidt  Anne Schrimpf  Ralf Schulz 《Fisheries Management and Ecology》2020,27(2):170-184

The genetic structure of the gadiform fish species, burbot Lota lota L., was investigated across Germany to derive management options for facilitating the preservation of genetic diversity. Sequence analysis of the mitochondrial control region (n = 244) and microsatellite analysis (n = 861) of specimens from 20 sites revealed genetic structuring between major river basins, and particularly between lake and river habitats. The admixture zone between the Eurasian and West European phylogenetic clades in Lake Constance was confirmed and expanded to include the drainage basins of the rivers Rhine and Schlei/Trave. Haplotype distribution and private haplotypes in single river basins indicated population differentiation and imply that German burbot constituted an important part of the entire species' diversity. The derived genetic structuring has implications for future stocking programmes and the preservation of the adaptive potential of burbot, a guiding species for oligotrophic lakes in Europe.  相似文献   

Can genetic diversity be maintained during mass selection of the Chinese mitten crab,Eriocheir sinensis?          下载免费PDF全文

Jie He  Qing Liu  Yongxu Cheng 《Aquaculture Research》2018,49(4):1606-1615

The Chinese mitten crab (Eriocheir sinensis) is an important aquaculture species and food source in Eastern Asia. This study assesses the changes in genetic diversity in successive generations of early‐ and late‐maturing strains of E. sinensis using 30 microsatellite markers with high polymorphism. The mean average number of alleles (N) in the founder population (G0), first generation (G1), second generation (G2) and third generation (G3) of the early‐maturing strain were 18.367, 14.800, 16.400 and 16.533, respectively; while in late‐maturing strain the values were 18.500, 16.267, 14.367 and 16.533 respectively. Likewise, there was a slight decline in average allelic richness (R_s) in the three successive generations. In both strains, the mean observed heterozygosity (H_o) remained relatively constant for the early‐maturing strain and the values were 0.655, 0.667, 0.685 and 0.705, respectively; and for the late‐maturing strain these were 0.665, 0.672, 0.688 and 0.702 respectively. Similarly, the expected heterozygosity (H_e) remained constant, ranging from 0.823 to 0.854. There was a decrease in effective population sizes (N_e) of the early‐maturing strain with successive generations: values were 492.2, 35.0, 134.7 and 193.2, respectively; while the values in the late‐maturing strain were 1268.5, 75.6, 111.5 and 97.2 respectively. All pairwise population distances were very close in both strains. In conclusion, these results suggest that mass selection of E. sinensis did not significantly diminish genetic diversity although there was a decline for the N_e. Therefore, it is important to maintain sufficient broodstock numbers and a large effective population when following a selective breeding programme.  相似文献   

Population structure,genetic diversity,and sexual state of the rice brown spot pathogen Bipolaris oryzae from three Asian countries          下载免费PDF全文

A. Ahmadpour  C. Castell‐Miller  M. Javan‐Nikkhah  M. R. Naghavi  F. P. Dehkaei  Y. Leng  K. D. Puri  S. Zhong 《Plant pathology》2018,67(1):181-192

Bipolaris oryzae causes brown spot in rice (Oryza sativa) inflicting substantial grain yield losses worldwide. Knowledge of the population structure, genetic diversity and sexual recombination of the fungal pathogen can help to implement effective disease management strategies. In this study, B. oryzae isolates sampled from Iran, the Philippines and Japan were analysed with 12 simple‐sequence repeat (SSR) markers, newly developed from the genome sequence of the fungus. Among the 288 B. oryzae isolates genotyped, 278 unique haplotypes were identified. High genotype numbers (richness) with even distribution (evenness) were found within the collection sites. Both mating types, MAT1‐1 and MAT1‐2, were present in each collection area, and the sexual state was induced under controlled conditions with production of viable ascospores. However, the tests of linkage disequilibrium rejected of the hypothesis of random mating. Discriminant analysis of principal components (DAPC) revealed that the B. oryzae collection formed three clusters, each consisting of isolates from different collection sites. Analysis of molecular variance (amova ) showed that genetic variation among clusters was 18.7%, with the rest of the variation distributed within clusters (R_ST = 0.187, P < 0.001). Statistically significant pairwise genetic differentiation was found between the clusters. These results show that Asian B. oryzae isolates are genetically diverse, and, overall, distributed in three groups. These findings will be helpful in managing the disease and guide the use of representative isolates needed for selection of resistant rice varieties.  相似文献   

Genetic diversity of Puccinia striiformis from cereals in Alberta,Canada     

M. D. Holtz  K. Kumar  J. L. Zantinge  K. Xi 《Plant pathology》2014,63(2):415-424

Stripe rust of wheat caused by Puccinia striiformis f. sp. tritici has recently become a production problem on wheat in Alberta, Canada, and stripe rust of barley caused by P. striiformis f. sp. hordei occurs regularly. A total of 261 isolates of P. striiformis were collected from wheat, barley, Hordeum jubatum and triticale plants in Alberta, Canada from 2007 to 2012, and compared to isolates from other provinces and the USA. The genetic diversity of the pathogen was assessed using 11 simple sequence repeat (SSR) markers and by examining a length polymorphism in the ribosomal DNA (rDNA) intergenic spacer 1 (IGS1) region. A total of 28 SSR genotypes were detected within Alberta. The 13 genotypes common on wheat (P. striiformis f. sp. tritici) were distinct from the 15 genotypes common on barley (P. striiformis f. sp. hordei). Four SSR genotypes, two within each forma specialis, represented 85% of the isolates recovered. Genotypic diversity was low, population genetic analysis indicated a clonal structure, and the genotypes were widely dispersed. In both formae speciales, the dominant genotype varied between years. The second most common P. striiformis f. sp. hordei genotype was found to be more closely related to older P. striiformis f. sp. tritici genotypes from the USA than to other P. striiformis f. sp. hordei genotypes.  相似文献   

Diversity of Phytophthora infestans from Poland     

M. Chmielarz  S. Sobkowiak  K. Dębski  D. E. L. Cooke  M. B. Brurberg  J. Śliwka 《Plant pathology》2014,63(1):203-211

A collection of 96 Polish isolates of Phytophthora infestans sampled in the years 2006, 2008 and 2009 were analysed using phenotypic and genotypic markers. Mating type, virulence, resistance to metalaxyl, mitochondrial haplotype and polymorphism at 12 simple sequence repeat (SSR) loci were determined. The majority of isolates were of the A1 mating type, mitochondrial haplotype Ia and sensitive to metalaxyl. Virulence factors against potato R genes R1, R3, R4, R7, R10 and R11 were present in most isolates. Genotyping using SSR markers revealed high genetic diversity within the Polish P. infestans population. Amongst the 96 isolates 66 unique genotypes were identified, 49 of which were observed only in single isolates. Eight isolates of the genotype 13_A2 lineage that has been reported in other parts of Europe were also found in Poland. The implications of these results are discussed.  相似文献   

Development and characterization of a new set of 164 polymorphic EST‐SSR markers for diversity and breeding studies in rubber tree (Hevea brasiliensis Müll. Arg.)     

Philippe Cubry  Valérie Pujade‐Renaud  Dominique Garcia  Sandra Espeout  Vincent Le Guen  Françoise Granet  Marc Seguin 《Plant Breeding》2014,133(3):419-426

Despite its economic importance and recent genome release, the need for molecular tools for Hevea brasiliensis is high. In the frame of a disease resistance study, EST sequences were retrieved from public database or generated by sequencing SSH libraries. Sequences were trimmed and microsatellite motifs searched using an ad hoc bioinformatic pipeline, and pairs of primers for the amplification of candidate markers were generated. We found a total of 10 499 unigenes from both sources of sequences, and 673 microsatellites motifs were detected using the default parameters of the pipeline. Two hundred sixty‐four primer pairs were tested and 226 (85.6%) successfully amplified. Out of the amplified candidate markers, 164 exhibited polymorphism. Relationships based on dendrograms using simple matching index and diversity statistics based on EST‐SSRs were compared with Genomic SSRs, showing the potentialities of EST‐derived microsatellites for resistance studies but also for population genetics approaches.  相似文献   

Estimates of Heritability of Larval and Early Juvenile Growth Traits in Red Drum (Sciaenops ocellatus)     

Liang Ma  Delbert M. Gatlin III  John R. Gold 《Journal Of Applied Aquaculture》2013,25(2):134-147

ABSTRACT

Eighteen to 29 families of red drum were generated via spontaneous spawning of multiple sets of three dams?×?two sires. In 2002, offspring from spawning events were grown in separate larval ponds to a mean TL of 30.4 mm. In 2003, offspring from spawning events were individually passive integrated transponder (PIT)-tagged and grown in “common-garden” tanks from 121.9 to 166.6 mm. Offspring in both experiments were assigned to parents based on genotypes at four microsatellite loci. Heritability estimates were 0.24?±?0.06 (larval TL) and 0.48?±?0.16 (juvenile-specific growth rate in length) and indicate a significant genetic component for both traits.  相似文献   

Triploid Induction in Atlantic Cod (Gadus morhua L.) by the Use of Different Pressure Levels     

Albert K. D. Imsland  Trine Haugen  Susanne Håvardstun  Anders Mangor-Jensen 《Journal Of Applied Aquaculture》2013,25(3):252-262

Different levels of pressure were investigated to see if it was possible to induce triploidy at a lower pressure than previously used (600 bar) for Atlantic cod (Gadus morhua). Newly fertilized eggs were exposed to different levels of pressure: 400, 500, and 600 bar, and one control group (no pressure). Induction of triploidy occurred at each pressure level used in this experiment. Mean weight and length at the termination of the trial period was significantly lower, in the 400 bar group, compared to the other treatment groups. Microsatellite loci analysis revealed over 90% triploid outcome in each experimental group. Lower incidence of deformities was seen in the 400 bar group compared to the 500 and 600 bar groups. Overall this study demonstrated successful triploid induction at both low (400 bar) and medium (500 bar) pressures.  相似文献   

Characterization and genomic annotation of polymorphic EST‐SSR loci in Litopenaeus vannamei shrimp     

Camilla A Santos  Bruno C Rossini  Carla G Marques  Pedro M Galetti Jr  Patrícia D Freitas 《Aquaculture Research》2012,43(10):1567-1570

In the present work, EST‐SSR (expressed sequence tag‐simple sequence repeat) loci were obtained by screening 45 000 ESTs from the Pacific white shrimp Litopenaeus vannamei, which was available in a database of the ShEST (Shrimp EST Genome Project) consortium. Fifty‐two of 600 EST‐SSR loci were selected. From this total, 21 EST‐SSRs were polymorphic among 40 individuals and had their gene products ascribed. Two to 20 alleles per locus were detected and the observed heterozygosity ranged from 0.15 to 0.86. Eight loci presented a significant heterozygote deficit after the Bonferroni correction, which was attributed to null alleles. Seven loci were able to have their protein products, molecular functions and biological processes determined. Our results are promising for future studies that relate the levels of these gene polymorphisms with different biological responses to stress in aquaculture.  相似文献