scholarly journals Testing for population decline using maximal linkage disequilibrium blocks

2019 ◽  
Author(s):  
Elise Kerdoncuff ◽  
Amaury Lambert ◽  
Guillaume Achaz
Keyword(s):  
Linkage Disequilibrium ◽  
Population Genomics ◽  
Conservation Status ◽  
Population Decline ◽  
Species Conservation ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Wide Range ◽  
Large Populations ◽  
Species Population

AbstractOnly 6% of known species have a conservation status. Methods that assess conservation statuses are often based on individual counts and are thus too laborious to be generalized to all species. Population genomics methods that infer past variations in population size are easy to use but limited to the relatively distant past. Here we propose a population genomics approach that tests for recent population decline and may be used to assess species conservation statuses. More specifically, we study Maximal Recombination Free (MRF) blocks, that are segments of a sequence alignment inherited from a common ancestor without recombination. MRF blocks are relatively longer in small than in large populations. We use the distribution of MRF block lengths rescaled by their mean to test for recent population decline. However, because MRF blocks are difficult to detect, we also consider Maximal Linkage Disequilibrium (MLD) blocks, which are runs of single nucleotide polymorphisms compatible with a single tree. We develop a new method capable of inferring a very recent decline (e.g. with a detection power of 50% for populations which size was halved to N, 0.05 ×N generations ago) from rescaled MLD block lengths. Our framework could serve as a basis for quantitative tools to assess conservation status in a wide range of species.

Protein Variation in ADH and ADH-RELATED in Drosophila pseudoobscura: Linkage Disequilibrium Between Single Nucleotide Polymorphisms and Protein Alleles

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 673-687
Author(s):  
Stephen W Schaeffer ◽  
C Scott Walthour ◽  
Donna M Toleno ◽  
Anna T Olek ◽  
Ellen L Miller
Keyword(s):  
Linkage Disequilibrium ◽  
Single Nucleotide Polymorphisms ◽  
Drosophila Pseudoobscura ◽  
Linkage Disequilibrium Mapping ◽  
Nucleotide Polymorphisms ◽  
Neutral Model ◽  
Significant Linkage Disequilibrium ◽  
Single Nucleotide ◽  
Synonymous Sites ◽  
Significant Linkage

Abstract A 3.5-kb segment of the alcohol dehydrogenase (Adh) region that includes the Adh and Adh-related genes was sequenced in 139 Drosophila pseudoobscura strains collected from 13 populations. The Adh gene encodes four protein alleles and rejects a neutral model of protein evolution with the McDonald-Kreitman test, although the number of segregating synonymous sites is too high to conclude that adaptive selection has operated. The Adh-related gene encodes 18 protein haplotypes and fails to reject an equilibrium neutral model. The populations fail to show significant geographic differentiation of the Adh-related haplotypes. Eight of 404 single nucleotide polymorphisms (SNPs) in the Adh region were in significant linkage disequilibrium with three ADHR protein alleles. Coalescent simulations with and without recombination were used to derive the expected levels of significant linkage disequilibrium between SNPs and 18 protein haplotypes. Maximum levels of linkage disequilibrium are expected for protein alleles at moderate frequencies. In coalescent models without recombination, linkage disequilibrium decays between SNPs and high frequency haplotypes because common alleles mutate to haplotypes that are rare or that reach moderate frequency. The implication of this study is that linkage disequilibrium mapping has the highest probability of success with disease-causing alleles at frequencies of 10%.

scholarly journals Genome-Wide Patterns of Homozygosity Reveal the Conservation Status in Five Italian Goat Populations

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1510
Author(s):  
Salvatore Mastrangelo ◽  
Rosalia Di Gerlando ◽  
Maria Teresa Sardina ◽  
Anna Maria Sutera ◽  
Angelo Moscarelli ◽  
...  
Keyword(s):  
Conservation Status ◽  
Phenotypic Traits ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Local Populations ◽  
Genomic Technologies ◽  
Fitness Traits ◽  
Genome Wide ◽  
Breeding Schemes ◽  
Genomic Inbreeding

The application of genomic technologies has facilitated the assessment of genomic inbreeding based on single nucleotide polymorphisms (SNPs). In this study, we computed several runs of homozygosity (ROH) parameters to investigate the patterns of homozygosity using Illumina Goat SNP50 in five Italian local populations: Argentata dell’Etna (N = 48), Derivata di Siria (N = 32), Girgentana (N = 59), Maltese (N = 16) and Messinese (N = 22). The ROH results showed well-defined differences among the populations. A total of 3687 ROH segments >2 Mb were detected in the whole sample. The Argentata dell’Etna and Messinese were the populations with the lowest mean number of ROH and inbreeding coefficient values, which reflect admixture and gene flow. In the Girgentana, we identified an ROH pattern related with recent inbreeding that can endanger the viability of the breed due to reduced population size. The genomes of Derivata di Siria and Maltese breeds showed the presence of long ROH (>16 Mb) that could seriously impact the overall biological fitness of these breeds. Moreover, the results confirmed that ROH parameters are in agreement with the known demography of these populations and highlighted the different selection histories and breeding schemes of these goat populations. In the analysis of ROH islands, we detected harbored genes involved with important traits, such as for milk yield, reproduction, and immune response, and are consistent with the phenotypic traits of the studied goat populations. Finally, the results of this study can be used for implementing conservation programs for these local populations in order to avoid further loss of genetic diversity and to preserve the production and fitness traits. In view of this, the availability of genomic data is a fundamental resource.

scholarly journals Differences in mate pairings of hatchery and natural origin coho salmon inferred from offspring genotypes

2021 ◽  
Author(s):  
H L Auld ◽  
D P Jacobson ◽  
A C Rhodes ◽  
M A Banks
Keyword(s):  
Mate Choice ◽  
Captive Breeding ◽  
Population Genomics ◽  
Coho Salmon ◽  
Genotyping By Sequencing ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Natural Origin ◽  
In Captivity ◽  
Genetic Level

Abstract Captive breeding can affect how sexual selection acts on subsequent generations. One context where this is important is in fish hatcheries. In many salmon hatcheries, spawning is controlled artificially and offspring are reared in captivity before release into the wild. While previous studies have suggested that hatchery and natural origin fish may make different mate choice decisions, it remains to be determined how hatchery fish may be making different mate choice decisions compared to natural origin fish at a genetic level. Using genotyping-by-sequencing (GBS), we identify single nucleotide polymorphisms (SNPs) associated with variation in mate pairings from a natural context involving hatchery and natural origin coho salmon (Oncorhynchus kisutch). In both natural origin and hatchery mate pairs, we observed more SNPs with negative assortment, than positive assortment. However, only 3% of the negative assortment SNPs were shared between the two mating groups, and 1% of the positive assortment SNPs were shared between the two mating groups, indicating divergence in mating cues between wild and hatchery raised salmon. These findings shed light on mate choice in general and may have important implications in the conservation management of species as well as for improving other captive breeding scenarios. There remains much to discover about mate choice in salmon and research described here reflects our intent to test the potential of ongoing advances in population genomics to develop new hatchery practices that may improve the performance of hatchery offspring, lessening the differences and thus potential impacts upon wild stocks.

The effect of linkage disequilibrium on the estimates of Single Nucleotide Polymorphic effects

2009 ◽  
Vol 2009 ◽  
pp. 44-44
Author(s):  
K Moore ◽  
J Gibson ◽  
D Johnston
Keyword(s):  
Linkage Disequilibrium ◽  
Single Nucleotide Polymorphisms ◽  
Genetic Improvement ◽  
Dairy Herd ◽  
Physical Distance ◽  
Causative Mutation ◽  
Nucleotide Polymorphisms ◽  
Production Traits ◽  
Single Nucleotide Polymorphic ◽  
Single Nucleotide

The identification and exploitation of single nucleotide polymorphisms (SNP) associated with production traits present new opportunities for livestock genetic improvement. Often the identified SNP is not the causative mutation but rather is in some degree of linkage disequilibrium (LD). LD markers within 5cM can be considered as direct markers for the causative mutation because they are located close to the causative mutation (Dekkers, 2004). In a dairy herd, Farnir et al., (2000) estimated that the average LD, measured as D′ was 0.5 for loci pairs positioned within 5cM. Goddard et al., (2006) estimated that LD measured as r2 decreased rapidly as the physical distance between loci increased; at a separating distance of 0.5Mb the LD (r2) was only approximately 0.2. The aim of this work was to use stochastic simulation to investigate the effect that the distance between the SNP and causative mutation had on the accuracy of estimating additive and dominance effects of the causative mutation.

scholarly journals simuG: a general-purpose genome simulator

2019 ◽  
Vol 35 (21) ◽  
pp. 4442-4444 ◽  
Author(s):  
Jia-Xing Yue ◽  
Gianni Liti
Keyword(s):  
Copy Number Variants ◽  
General Purpose ◽  
Supplementary Information ◽  
Nucleotide Polymorphisms ◽  
Bioinformatics Analyses ◽  
Full Spectrum ◽  
Single Nucleotide ◽  
Genomic Variants ◽  
Wide Range ◽  
Simulation Based

Abstract Summary Simulated genomes with pre-defined and random genomic variants can be very useful for benchmarking genomic and bioinformatics analyses. Here we introduce simuG, a lightweight tool for simulating the full-spectrum of genomic variants (single nucleotide polymorphisms, Insertions/Deletions, copy number variants, inversions and translocations) for any organisms (including human). The simplicity and versatility of simuG make it a unique general-purpose genome simulator for a wide-range of simulation-based applications. Availability and implementation Code in Perl along with user manual and testing data is available at https://github.com/yjx1217/simuG. This software is free for use under the MIT license. Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals Identification of tag single-nucleotide polymorphisms in regions with varying linkage disequilibrium

BMC Genetics ◽  
2005 ◽  
Vol 6 (Suppl 1) ◽  
pp. S73 ◽  
Author(s):  
Priya Duggal ◽  
Elizabeth M Gillanders ◽  
Rasika A Mathias ◽  
Grace P Ibay ◽  
Alison P Klein ◽  
...  
Keyword(s):  
Linkage Disequilibrium ◽  
Single Nucleotide Polymorphisms ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide

Functional nonsynonymous single nucleotide polymorphisms from the TGF-β protein interaction network

2007 ◽  
Vol 29 (2) ◽  
pp. 109-117 ◽  
Author(s):  
Sevtap Savas ◽  
Ian W. Taylor ◽  
Jeff L. Wrana ◽  
Hilmi Ozcelik
Keyword(s):  
Single Nucleotide Polymorphisms ◽  
Protein Interactions ◽  
Transforming Growth Factor ◽  
Conservation Status ◽  
Genetic Variations ◽  
Phosphorylation Sites ◽  
Nucleotide Polymorphisms ◽  
Protein Protein Interactions ◽  
Single Nucleotide ◽  
Putative Protein

Protein complexes mediated by protein-protein interactions are essential for many cellular functions. Transforming growth factor (TGF)-β signaling involves a cascade of protein-protein interactions and malfunctioning of this pathway has been implicated in human diseases. Using an in silico approach, we analyzed the naturally occurring human genetic variations from the proteins involved in the TGF-β signaling (10 TGF-β proteins and 242 other proteins interacting with them) to identify the ones that have potential biological consequences. All proteins were searched in the dbSNP database for the presence of nonsynonymous single nucleotide polymorphisms (nsSNPs). A total of 118 validated nsSNPs from 63 proteins were retrieved and analyzed in terms of 1) evolutionary conservation status, 2) being located in a functional protein domain or motif, and 3) altering putative protein motif or phosphorylation sites. Our results indicated the presence of 31 nsSNPs that occurred at evolutionarily conserved residues, 37 nsSNPs were located in protein domains, motifs, or repeats, and 46 nsSNPs were predicted to either create or abolish putative protein motifs or phosphorylation sites. We undertook this study to analyze the human genetic variations that can affect the protein function and the TGF-β signaling. The nsSNPs reported in here can be characterized by experimental approaches to elucidate their exact biological roles and whether they are related to human disease.

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