scholarly journals Whole Genome Linkage Disequilibrium and Effective Population Size in a Coho Salmon (Oncorhynchus kisutch) Breeding Population Using a High-Density SNP Array

2019 ◽  
Vol 10 ◽  
Author(s):  
Agustín Barría ◽  
Kris A. Christensen ◽  
Grazyella Yoshida ◽  
Ana Jedlicki ◽  
Jong S. Leong ◽  
...  
2018 ◽  
Author(s):  
Agustín Barría ◽  
Kris A. Christensen ◽  
Grazyella Yoshida ◽  
Ana Jedlicki ◽  
Jean P. Lhorente ◽  
...  

AbstractThe estimation of linkage disequilibrium between molecular markers within a population is critical when establishing the minimum number of markers required for association studies, genomic selection and for inferring historical events influencing different populations. This work aimed to evaluate the extent and decay of linkage disequilibrium in a coho salmon breeding population using ddRAD genomic markers.Linkage disequilibrium was estimated between a total of 7,505 SNPs found in 62 individuals (33 dams and 29 sires) from the breeding population. The makers encompass all 30 coho salmon chromosomes and comprise 1,655.19 Mb of the genome. The average density of markers per chromosome ranged from 3.45 to 6.11 per 1 Mbp. The minor allele frequency averaged 0.20 (with a range from 0.08 to 0.50). The overall average linkage disequilibrium among SNPs pairs measured as r2 was 0.054. The Average r2 value decreased with increasing physical distance, with values ranging from 0.37 to 0.054 at distances lower than 1 kb and up to 10 Mb, respectively. An r2 threshold of 0.1 was reached at distance of approximately 1.3 Mb. Chromosomes Okis05, Okis15 and Okis28 showed high levels of linkage disequilibrium (> 0.20 at distances lower than 1 Mb). Average r2 values were lower than 0.1 for all chromosomes at distances greater than 4 Mb. Linkage disequilibrium values suggest that whole genome association and selection studies could be performed using about 75,000 SNPs in aquaculture populations (depending on the trait under investigation). From the identified SNPs, an effective population size of 100 was estimated for the population 10 generation ago, and 1,000, for 139 generations ago.Based on the extent of r2 decay, we suggest that at least 75,000 SNPs would be necessary for an association mapping study. Over 100,000 SNPs would be necessary for a high power study, in the current coho salmon population.


Aquaculture ◽  
2014 ◽  
Vol 420-421 ◽  
pp. S15-S19 ◽  
Author(s):  
José M. Yáñez ◽  
Liane N. Bassini ◽  
Michael Filp ◽  
Jean P. Lhorente ◽  
Raúl W. Ponzoni ◽  
...  

BMC Genetics ◽  
2017 ◽  
Vol 18 (1) ◽  
Author(s):  
Vincent Prieur ◽  
Shannon M. Clarke ◽  
Luiz F. Brito ◽  
John C. McEwan ◽  
Michael A. Lee ◽  
...  

Animals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 361 ◽  
Author(s):  
Shuqi Diao ◽  
Shuwen Huang ◽  
Zhiting Xu ◽  
Shaopan Ye ◽  
Xiaolong Yuan ◽  
...  

To investigate the genetic diversity, population structure, extent of linkage disequilibrium (LD), effective population size (Ne), and selection signatures in indigenous pigs from Guangdong and Guangxi in China, 226 pigs belonging to ten diverse populations were genotyped using single nucleotide polymorphism (SNP) chips. The genetic divergence between Chinese and Western pigs was determined based on the SNP chip data. Low genetic diversity of Dahuabai (DHB), Luchuan (LC), Lantang (LT), and Meihua (MH) pigs, and introgression of Western pigs into Longlin (LL), MH, and Yuedonghei (YDH) pigs were detected. Analysis of the extent of LD showed that indigenous pigs had low LD when pairwise SNP distance was short and high LD when pairwise SNP distance was long. Effective population size analysis showed a rapid decrease for Chinese indigenous pigs, and some pig populations had a relatively small Ne. This result indicated the loss of genetic diversity in indigenous pigs, and introgression from Western commercial pigs. Selection signatures detected in this study overlapped with meat quality traits, such as drip loss, intramuscular fat content, meat color b*, and average backfat thickness. Our study deepened understanding of the conservation status and domestication of Chinese indigenous pigs.


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