scholarly journals “Theory, practice, and conservation in the age of genomics: the Galápagos giant tortoise as a case study”

2017 ◽  
Author(s):  
Stephen J Gaughran ◽  
Maud C Quinzin ◽  
Joshua M Miller ◽  
Ryan C Garrick ◽  
Danielle L Edwards ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Differentiation ◽  
Sampling Design ◽  
Natural Populations ◽  
Molecular Techniques ◽  
Model Organisms ◽  
Strong Impact ◽  
Nucleotide Polymorphisms ◽  
Distinct Structure ◽  
Snp Data

AbstractHigh-throughput DNA sequencing allows efficient discovery of thousands of single nucleotide polymorphisms (SNPs) in non-model species. Population genetic theory predicts that this large number of independent markers should provide detailed insights into population structure, even when only a few individuals are sampled. Still, sampling design can have a strong impact on such inferences. Here, we use simulations and empirical SNP data to investigate the impacts of sampling design on estimating genetic differentiation among populations that represent three species of Galápagos giant tortoises (Chelonoidisspp.). Though microsatellite and mitochondrial DNA analyses have supported the distinctiveness of these species, a recent study called into question how well these markers matched with data from genomic SNPs, thereby questioning decades of studies in non-model organisms. Using >20,000 genome-wide SNPs from 30 individuals from three Galápagos giant tortoise species, we find distinct structure that matches the relationships described by the traditional genetic markers. Furthermore, we confirm that accurate estimates of genetic differentiation in highly structured natural populations can be obtained using thousands of SNPs and 2-5 individuals, or hundreds of SNPs and 10 individuals, but only if the units of analysis are delineated in a way that is consistent with evolutionary history. We show that the lack of structure in the recent SNP-based study was likely due to unnatural grouping of individuals and erroneous genotype filtering. Our study demonstrates that genomic data enable patterns of genetic differentiation among populations to be elucidated even with few samples per population, and underscores the importance of sampling design. These results have specific implications for studies of population structure in endangered species and subsequent management decisions.“Modern molecular techniques provide unprecedented power to understand genetic variation in natural populations. Nevertheless, application of this information requires sound understanding of population genetics theory.”- Fred Allendorf (2017, p. 420)

scholarly journals Population Genetics and Evolution Analysis Reveal Diversity and Origin of Ammopiptanthus in China.

2021 ◽  
Author(s):  
Guai-qiang Chai ◽  
Yizhong Duan ◽  
Peipei Jiao ◽  
Zhongyu Du ◽  
Furen Kang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Association Studies ◽  
Natural Populations ◽  
Principal Component ◽  
Nucleotide Polymorphisms ◽  
Future Design ◽  
Ammopiptanthus Nanus ◽  
Genome Wide

Abstract Background：Elucidating and revealing the population genetic structure, genetic diversity and recombination is essential for understanding the evolution and adaptation of species. Ammopiptanthus, which is an endangered survivor from the Tethys in the Tertiary Period, is the only evergreen broadleaf shrub grown in Northwest of China. However, little is known about its genetic diversity and underlying adaptation mechanisms. Results：Here, 111 Ammopiptanthus individuals collected from fifteen natural populations in estern China were analyzed by means of the specific locus amplified fragment sequencing (SLAF-seq). Based on the single nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) detected by SLAF-seq, genetic diversity and markers associated with climate and geographical distribution variables were identified. The results of genetic diversity and genetic differentiation revealed that all fifteen populations showed medium genetic diversity, with PIC values ranging from 0.1648 to 0.3081. AMOVA and Fst indicated that a low genetic differentiation existed among populations. Phylogenetic analysis showed that NX-BG and NMG-DQH of fifteen populations have the highest homology，while the genetic structure analysis revealed that these Ammopiptanthus germplasm accessions were structured primarily along the basis of their geographic collection, and that an extensive admixture occurred in each group. In addition, the genome-wide linkage disequilibrium (LD) and principal component analysis showed that Ammopiptanthus nanus had a more diverse genomic background, and all genetic populations were clearly distinguished, although different degrees of introgression were detected in these groups. Conclusion：Our study could provide guidance to the future design of association studies and the systematic utilization and protection of the genetic variation characterizing the Ammopiptanthus.

scholarly journals RAD sequencing resolves fine-scale population structure in a benthic invertebrate: implications for understanding phenotypic plasticity

2017 ◽  
Vol 4 (2) ◽  
pp. 160548 ◽  
Author(s):  
David L. J. Vendrami ◽  
Luca Telesca ◽  
Hannah Weigand ◽  
Martina Weiss ◽  
Katie Fawcett ◽  
...  
Keyword(s):  
Population Structure ◽  
Phenotypic Plasticity ◽  
Molecular Ecology ◽  
Natural Populations ◽  
Benthic Invertebrate ◽  
Shell Shape ◽  
Rad Sequencing ◽  
Fine Scale ◽  
Nucleotide Polymorphisms ◽  
Scale Population

The field of molecular ecology is transitioning from the use of small panels of classical genetic markers such as microsatellites to much larger panels of single nucleotide polymorphisms (SNPs) generated by approaches like RAD sequencing. However, few empirical studies have directly compared the ability of these methods to resolve population structure. This could have implications for understanding phenotypic plasticity, as many previous studies of natural populations may have lacked the power to detect genetic differences, especially over micro-geographic scales. We therefore compared the ability of microsatellites and RAD sequencing to resolve fine-scale population structure in a commercially important benthic invertebrate by genotyping great scallops ( Pecten maximus ) from nine populations around Northern Ireland at 13 microsatellites and 10 539 SNPs. The shells were then subjected to morphometric and colour analysis in order to compare patterns of phenotypic and genetic variation. We found that RAD sequencing was superior at resolving population structure, yielding higher F st values and support for two distinct genetic clusters, whereas only one cluster could be detected in a Bayesian analysis of the microsatellite dataset. Furthermore, appreciable phenotypic variation was observed in size-independent shell shape and coloration, including among localities that could not be distinguished from one another genetically, providing support for the notion that these traits are phenotypically plastic. Taken together, our results suggest that RAD sequencing is a powerful approach for studying population structure and phenotypic plasticity in natural populations.

scholarly journals Enhanced genetic differentiation of Japanese chum salmon identified from a meta-analysis of allele frequencies

2019 ◽  
Author(s):  
Shuichi Kitada ◽  
Hirohisa Kishino
Keyword(s):  
Population Structure ◽  
Genetic Differentiation ◽  
Chum Salmon ◽  
Meta Analysis ◽  
Distribution Range ◽  
Allele Frequencies ◽  
Geographical Information ◽  
Data Sets ◽  
Nucleotide Polymorphisms ◽  
Athletic Ability

AbstractThe number of individuals returning to Japan, the location of the world’s largest chum salmon hatchery program, has declined substantially over two decades. To find the genetic cause of this severe decline never previously experienced, we analyzed published genetic data sets for adult chum salmon, namely, 10 microsatellites, 53 single nucleotide polymorphisms (SNPs) and a combined mitochondrial DNA locus (mtDNA3), and three isozymes, from 576 locations in the distribution range (n = 76,363). The SNPs were selected for stock identification to achieve high accuracy, were highly differentiated in the distribution range and included important genes related to reproduction, growth and immune responses. By contrasting the genetic differentiation of these genes with the population structure estimated from the neutral microsatellite markers, we identified genes that distort the neutral population structure. We matched the sampling locations of SNPs and isozymes with those of microsatellites based on geographical information, and performed regression analyses of SNP and isozyme allele frequencies of matched locations on the population structure. TreeMix analysis indicated two admixture events, from Japan/Korea to Russia and the Alaskan Peninsula. Meta-analysis of allele frequencies identified three outliers, mtDNA3 (control region and NADH-3), GnRH373 (gonadotropin-releasing hormone) and U502241 (unknown), which showed enhanced differentiation in Japanese/Korean populations compared with the others. GnRH improves stream odor discrimination and has increased expression in adult chum salmon brains during homing migration, suggesting that the current admixture was caused by GnRH373 differentiation. mtDNA plays a key role in endurance exercise training, energy metabolism and oxygen consumption, suggesting that the significant reduction in mtDNA3 allele frequencies reduced aerobic athletic ability, as observed in YouTube videos. Our analyses relied on limited data sets, though they were the best available. Clearly, genome-wide data will be needed to fully address this issue.

scholarly journals Genetic Diversity Assessed by Genotyping by Sequencing (GBS) in Watermelon Germplasm

Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 822 ◽  
Author(s):  
Kyung Jun Lee ◽  
Jung-Ro Lee ◽  
Raveendar Sebastin ◽  
Myoung-Jae Shin ◽  
Seong-Hoon Kim ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Discriminant Analysis ◽  
Single Nucleotide Polymorphisms ◽  
Genetic Differentiation ◽  
Principal Components ◽  
Genotyping By Sequencing ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Breeding Programs

Watermelon is an economically important vegetable fruit worldwide. The objective of this study was to conduct a genetic diversity of 68 watermelon accessions using single nucleotide polymorphisms (SNPs). Genotyping by sequencing (GBS) was used to discover SNPs and assess genetic diversity and population structure using STRUCTURE and discriminant analysis of principal components (DAPC) in watermelon accessions. Two groups of watermelons were used: 1) highly utilized 41 watermelon accessions at the National Agrobiodiversity Center (NAC) at the Rural Development Administration in South Korea; and 2) 27 Korean commercial watermelons. Results revealed the presence of four clusters within the populations differentiated principally based on seed companies. In addition, there was higher genetic differentiation among commercial watermelons of each company. It is hypothesized that the results obtained from this study would contribute towards the expansion of this crop as well as providing data about genetic diversity, which would be useful for the preservation of genetic resources or for future breeding programs.

scholarly journals Genome-wide assessment of genetic diversity and population structure in Magnolia odoratissima based on SLAF-Seq

2021 ◽  
Author(s):  
Tao Zhang ◽  
Xue Li ◽  
Shuilian He
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Natural Populations ◽  
Environmental Parameters ◽  
Candidate Snps ◽  
Small Populations ◽  
Nucleotide Polymorphisms ◽  
High Genetic Diversity ◽  
Genome Wide

Abstract Magnolia odoratissima is a highly threatened species with small populations and scattered distribution due to habitat fragmentation and human activity. The species is recognized as a Plant Species with Extremely Small Populations (PSESP) and is endemic to China. In the current study, the population structure and levels of genetic diversity of M. odoratissima in the five remaining natural populations and three cultivated populations were evaluated using single nucleotide polymorphisms (SNPs) derived from Specific-Locus Amplified Fragment Sequencing (SLAF-seq). A total of 180,650 SNP loci were found in seventy M. odoratissima individuals. The genome-wide Nei’s and Shannon’s nucleotide diversity indexes of the total M. odoratissima population were 0.3035 and 0.4695, respectively. The observed heterozygosity (Ho) and expected heterozygosity (He) were 0.1122 and 0.3011. Our results suggest that M. odoratissima has relatively high genetic diversity at the genomic level. FST and AMOVA indicated that high genetic differentiation existed among populations. A phylogenetic neighbor-joining tree, Bayesian model–based clustering and principal components analysis (PCA) all divided the studied M. odoratissima individuals into three distinct clusters. The Treemix analysis showed that there was low gene flow among the natural populations and a certain gene flow from the wild populations to the cultivated population (LS to KIB, and GN to JD). In addition, a total of 36 unique SNPs were detected as being significantly associated with environmental parameters (altitude, temperature and precipitation). These candidate SNPs were found to be involved in multiple pathways including several molecular functions and biological process, suggesting they may play key roles in environmental adaptation. Our results suggested that three distinct evolutionary significant units (ESUs) should be set up to conserve this critically endangered species.

scholarly journals Genetic diversity of Indigofera kirilowii Maxim. ex Palibin using AFLP makers

2019 ◽  
Vol 48 (4) ◽  
pp. 1237-1241
Author(s):  
Qikui Wu ◽  
Limin Sun ◽  
Xiaojing Liu ◽  
Xuan Wang ◽  
Xia Sun ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Length Polymorphism ◽  
North China ◽  
Fragment Length Polymorphism ◽  
Natural Populations ◽  
Geographic Location ◽  
High Genetic Diversity

The present studies were conducted to assess the genetic diversity and to infer population structure of 220 individuals of Indigofera kirilowii from 8 natural populations of Shandong province, north China, using amplified fragment length polymorphism (AFLP) markers. A total of 1589 AFLP bands were produced, of which 99.87% were polymorphic. High genetic diversity was considered (H = 0.1401; I = 0.2346), with high genetic differentiation (GST = 0.1058), while estimates of gene flow (Nm) were high in all analysis. No correlations were observed between geographic location and genetic diversity (r = –0.0901; p = 0.3293). Based on the results, here a strategy for the conservation of I. kirilowii germplasm was proposed.

Analysis of Inter-Chromosomal Distribution of Disease-Related Genes in Human Genome

2020 ◽  
Vol 21 (11) ◽  
pp. 1068-1077
Author(s):  
Xiaochao Sun ◽  
Bin Yang ◽  
Qunye Zhang
Keyword(s):  
Spatial Distribution ◽  
Model Organisms ◽  
Nucleotide Polymorphisms ◽  
Chromosomal Distribution ◽  
Single Nucleotide ◽  
Protein Coding ◽  
Single Chromosome ◽  
Deletion Mutations ◽  
Protein Coding Genes ◽  
Disease Related Genes

: Many studies have shown that the spatial distribution of genes within a single chromosome exhibits distinct patterns. However, little is known about the characteristics of inter-chromosomal distribution of genes (including protein-coding genes, processed transcripts and pseudogenes) in different genomes. In this study, we explored these issues using the available genomic data of both human and model organisms. Moreover, we also analyzed the distribution pattern of protein-coding genes that have been associated with 14 common diseases and the insert/deletion mutations and single nucleotide polymorphisms detected by whole genome sequencing in an acute promyelocyte leukemia patient. We obtained the following novel findings. Firstly, inter-chromosomal distribution of genes displays a nonstochastic pattern and the gene densities in different chromosomes are heterogeneous. This kind of heterogeneity is observed in genomes of both lower and higher species. Secondly, protein-coding genes involved in certain biological processes tend to be enriched in one or a few chromosomes. Our findings have added new insights into our understanding of the spatial distribution of genome and disease- related genes across chromosomes. These results could be useful in improving the efficiency of disease-associated gene screening studies by targeting specific chromosomes.

Genome-Wide Single Nucleotide Polymorphisms are Robust in Resolving Fine-Scale Population Genetic Structure of the Small Brown Planthopper, Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae)

2019 ◽  
Vol 112 (5) ◽  
pp. 2362-2368
Author(s):  
Yan Liu ◽  
Lei Chen ◽  
Xing-Zhi Duan ◽  
Dian-Shu Zhao ◽  
Jing-Tao Sun ◽  
...  
Keyword(s):  
Population Structure ◽  
Discriminant Analysis ◽  
Genetic Structure ◽  
Population Genetic ◽  
Brown Planthopper ◽  
Fine Scale ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Small Brown Planthopper ◽  
Scale Population

Abstract Deciphering genetic structure and inferring migration routes of insects with high migratory ability have been challenging, due to weak genetic differentiation and limited resolution offered by traditional genotyping methods. Here, we tested the ability of double digest restriction-site associated DNA sequencing (ddRADseq)-based single nucleotide polymorphisms (SNPs) in revealing the population structure relative to 13 microsatellite markers by using four small brown planthopper populations as subjects. Using ddRADseq, we identified 230,000 RAD loci and 5,535 SNP sites, which were present in at least 80% of individuals across the four populations with a minimum sequencing depth of 10. Our results show that this large SNP panel is more powerful than traditional microsatellite markers in revealing fine-scale population structure among the small brown planthopper populations. In contrast to the mixed population structure suggested by microsatellites, discriminant analysis of principal components (DAPC) of the SNP dataset clearly separated the individuals into four geographic populations. Our results also suggest the DAPC analysis is more powerful than the principal component analysis (PCA) in resolving population genetic structure of high migratory taxa, probably due to the advantages of DAPC in using more genetic variation and the discriminant analysis function. Together, these results point to ddRADseq being a promising approach for population genetic and migration studies of small brown planthopper.

scholarly journals Genome-wide SNPs redefines species boundaries and conservation units in the freshwater mussel genus Cyprogenia of North America

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyung Seok Kim ◽  
Kevin J. Roe
Keyword(s):  
Phylogenetic Analyses ◽  
Freshwater Mussel ◽  
Conservation Strategies ◽  
Nucleotide Polymorphisms ◽  
Conservation Units ◽  
Genetic Structuring ◽  
The North ◽  
Snp Data ◽  
Genome Wide ◽  
Significant Difference

AbstractDetailed information on species delineation and population genetic structure is a prerequisite for designing effective restoration and conservation strategies for imperiled organisms. Phylogenomic and population genomic analyses based on genome-wide double digest restriction-site associated DNA sequencing (ddRAD-Seq) data has identified three allopatric lineages in the North American freshwater mussel genus Cyprogenia. Cyprogenia stegaria is restricted to the Eastern Highlands and displays little genetic structuring within this region. However, two allopatric lineages of C. aberti in the Ozark and Ouachita highlands exhibit substantial levels (mean uncorrected FST = 0.368) of genetic differentiation and each warrants recognition as a distinct evolutionary lineage. Lineages of Cyprogenia in the Ouachita and Ozark highlands are further subdivided reflecting structuring at the level of river systems. Species tree inference and species delimitation in a Bayesian framework using single nucleotide polymorphisms (SNP) data supported results from phylogenetic analyses, and supports three species of Cyprogenia over the currently recognized two species. A comparison of SNPs generated from both destructively and non-destructively collected samples revealed no significant difference in the SNP error rate, quality and amount of ddRAD sequence reads, indicating that nondestructive or trace samples can be effectively utilized to generate SNP data for organisms for which destructive sampling is not permitted.

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