scholarly journals Conservation genomic analysis reveals ancient introgression and declining levels of genetic diversity in Madagascar’s hibernating dwarf lemurs

2019 ◽  
Author(s):  
Rachel C. Williams ◽  
Marina B. Blanco ◽  
Jelmer W. Poelstra ◽  
Kelsie E. Hunnicutt ◽  
Aaron A. Comeault ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genomic Analysis ◽  
Population Level ◽  
Comparative Genomic ◽  
Effective Population ◽  
High Coverage ◽  
Genome Wide ◽  
Conservation Concern ◽  
Genomic Regions ◽  
Dwarf Lemur

AbstractMadagascar’s biodiversity is notoriously threatened by deforestation and climate change. Many of these organisms are rare, cryptic, and severely threatened, making population-level sampling unrealistic. Such is the case with Madagascar’s dwarf lemurs (genus Cheirogaleus), the only obligate hibernating primate. We here apply comparative genomic approaches to generate the first genome-wide estimates of genetic diversity within dwarf lemurs. We generate a reference genome for the fat-tailed dwarf lemur, Cheirogaleus medius, and use this resource to facilitate analyses of high-coverage (~30x) genome sequences for wild-caught individuals representing species: C. sp. cf. medius, C. major, C. crossleyi and C. sibreei. This study represents the largest contribution to date of novel genomic resources for Madagascar’s lemurs. We find concordant phylogenetic relationships among the four lineages of Cheirogaleus across most of the genome, and yet detect a number of discordant genomic regions consistent with ancient admixture. We hypothesized that these regions could have resulted from adaptive introgression related to hibernation, indeed finding that genes associated with hibernation are present, though most significantly, that gene ontology categories relating to transcription are over-represented. We estimate levels of heterozygosity and find particularly low levels in an individual sampled from an isolated population of C. medius that we refer to as C. sp. cf. medius. Results are consistent with a recent decline in effective population size, which is evident across species. Our study highlights the power of comparative genomic analysis for identifying species and populations of conservation concern, as well as for illuminating possible mechanisms of adaptive phenotypic evolution.

scholarly journals Comparative Genomic Analysis Confirms Five Genetic Populations of the Select Agent, Rathayibacter toxicus

2020 ◽  
Vol 8 (3) ◽  
pp. 366
Author(s):  
Jarred Yasuhara-Bell ◽  
Mohammad Arif ◽  
Grethel Y. Busot ◽  
Rachel Mann ◽  
Brendan Rodoni ◽  
...  
Keyword(s):  
Genomic Analysis ◽  
The United States ◽  
Grass Species ◽  
Comparative Genomic ◽  
Underrepresented Populations ◽  
System A ◽  
Genome Wide ◽  
The Family ◽  
Study Support ◽  
Genomic Regions

Rathayibacter toxicus is a Gram-positive, nematode-vectored bacterium that infects several grass species in the family Poaceae. Unique in its genus, R. toxicus has the smallest genome, possesses a complete CRISPR-Cas system, a vancomycin-resistance cassette, produces tunicamycin, a corynetoxin responsible for livestock deaths in Australia, and is designated a Select Agent in the United States. In-depth, genome-wide analyses performed in this study support the previously designated five genetic populations, with a core genome comprising approximately 80% of the genome for all populations. Results varied as a function of the type of analysis and when using different bioinformatics tools for the same analysis; e.g., some programs failed to identify specific genomic regions that were actually present. The software variance highlights the need to verify bioinformatics results by additional methods; e.g., PCR, mapping genes to genomes, use of multiple algorithms). These analyses suggest the following relationships among populations: RT-IV ↔ RT-I ↔ RT-II ↔ RT-III ↔ RT-V, with RT-IV and RT-V being the most unrelated. This is the most comprehensive analysis of R. toxicus that included populations RT-I and RT-V. Future studies require underrepresented populations and more recent isolates from varied hosts and geographic locations.

scholarly journals Comparative Genomic Analysis Provides Insights into the Evolution and Genetic Diversity of Community-Genotype Sequence Type 72 Staphylococcus aureus Isolates

mSystems ◽  
2021 ◽  
Author(s):  
Wangxiao Zhou ◽  
Ye Jin ◽  
Yanzi Zhou ◽  
Yuan Wang ◽  
Luying Xiong ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Staphylococcus Aureus ◽  
Genomic Analysis ◽  
Comparative Genomic Analysis ◽  
Sequence Type ◽  
Comparative Genomic ◽  
Health Issues ◽  
Content Type ◽  
Genome Wide Analysis ◽  
Genome Wide

Understanding the evolution and dissemination of community-genotype ST72 Staphylococcus aureus isolates is important, as isolates of this lineage have rapidly spread into hospital settings and caused serious health issues. In this study, we first carried out genome-wide analysis of 107 global ST72 isolates to characterize the evolution and genetic diversity of the ST72 lineage.

scholarly journals Genome-wide increased copy number is associated with emergence of super-fit clones of the Irish potato famine pathogen Phytophthora infestans

2019 ◽  
Author(s):  
Brian J. Knaus ◽  
Javier F. Tabima ◽  
Shankar K. Shakya ◽  
Howard S. Judelson ◽  
Niklaus J. Grünwald
Keyword(s):  
Phytophthora Infestans ◽  
Copy Number ◽  
Genomic Analysis ◽  
Irish Potato ◽  
Comparative Genomic ◽  
High Coverage ◽  
Center Of Origin ◽  
Genome Wide ◽  
Potato Famine ◽  
Irish Potato Famine

AbstractThe plant pathogen that caused the Irish potato famine, Phytophthora infestans, continues to reemerge globally. These modern epidemics are caused by clonally reproducing lineages. In contrast, a sexual mode of reproduction is observed at its center of origin in Mexico. We conducted a comparative genomic analysis of 47 high coverage genomes to infer changes in genic copy number. We included samples from sexual populations at the center of origin as well as several dominant clonal lineages sampled worldwide. We conclude that sexual populations at the center of origin are diploid as was the lineage that caused the famine, while modern clonal lineages showed increased copy number (3x). Copy number variation (CNV) was found genome-wide and did not to adhere to the two-speed genome hypothesis. Although previously reported, tetraploidy was not found in any of the genomes evaluated. We propose a model of super-fit clone emergence supported by the epidemiological record (e.g., EU_13_A2, US-11, US-23) whereby higher copy number provides fitness leading to replacement of prior clonal lineages.

scholarly journals Genome assembly of the JD17 soybean provides a new reference genome for Comparative genomics

2021 ◽  
Author(s):  
Xinxin Yi ◽  
Jing Liu ◽  
Shengcai Chen ◽  
Hao Wu ◽  
Min Liu ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Genome Assembly ◽  
Reference Genome ◽  
De Novo ◽  
Genomic Analysis ◽  
Comparative Genomic ◽  
High Quality ◽  
Genome Wide ◽  
A Genome ◽  
Cultivated Soybean

Cultivated soybean (Glycine max) is an important source for protein and oil. Many elite cultivars with different traits have been developed for different conditions. Each soybean strain has its own genetic diversity, and the availability of more high-quality soybean genomes can enhance comparative genomic analysis for identifying genetic underpinnings for its unique traits. In this study, we constructed a high-quality de novo assembly of an elite soybean cultivar Jidou 17 (JD17) with chromsome contiguity and high accuracy. We annotated 52,840 gene models and reconstructed 74,054 high-quality full-length transcripts. We performed a genome-wide comparative analysis based on the reference genome of JD17 with three published soybeans (WM82, ZH13 and W05) , which identified five large inversions and two large translocations specific to JD17, 20,984 - 46,912 PAVs spanning 13.1 - 46.9 Mb in size, and 5 - 53 large PAV clusters larger than 500kb. 1,695,741 - 3,664,629 SNPs and 446,689 - 800,489 Indels were identified and annotated between JD17 and them. Symbiotic nitrogen fixation (SNF) genes were identified and the effects from these variants were further evaluated. It was found that the coding sequences of 9 nitrogen fixation-related genes were greatly affected. The high-quality genome assembly of JD17 can serve as a valuable reference for soybean functional genomics research.

scholarly journals Horizontal Gene Transfer Clarifies Taxonomic Confusion and Promotes the Genetic Diversity and Pathogenicity of Plesiomonas shigelloides

mSystems ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Zhiqiu Yin ◽  
Si Zhang ◽  
Yi Wei ◽  
Meng Wang ◽  
Shuangshuang Ma ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Evolutionary Dynamics ◽  
Genomic Analysis ◽  
Comparative Genomic ◽  
Content Type ◽  
Pan Genome ◽  
Long Time ◽  
Taxonomic Confusion

The taxonomic position of P. shigelloides has been the subject of debate for a long time, and until now, the evolutionary dynamics and pathogenesis of P. shigelloides were unclear. In this study, pan-genome analysis indicated extensive genetic diversity and the presence of large and variable gene repertoires. Our results revealed that horizontal gene transfer was the focal driving force for the genetic diversity of the P. shigelloides pan-genome and might have contributed to the emergence of novel properties. Vibrionaceae and Aeromonadaceae were found to be the predominant donor taxa for horizontal genes, which might have caused the taxonomic confusion historically. Comparative genomic analysis revealed the potential of P. shigelloides to cause intestinal and invasive diseases. Our results could advance the understanding of the evolution and pathogenesis of P. shigelloides, particularly in elucidating the role of horizontal gene transfer and investigating virulence-related elements.

scholarly journals Genome-Wide Runs of Homozygosity, Effective Population Size, and Detection of Positive Selection Signatures in Six Chinese Goat Breeds

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 938 ◽  
Author(s):  
Islam ◽  
Li ◽  
Liu ◽  
Berihulay ◽  
Abied ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Positive Selection ◽  
Candidate Genes ◽  
Runs Of Homozygosity ◽  
Selection Signatures ◽  
Effective Population ◽  
Signature Of Selection ◽  
Genomic Regions ◽  
Insight Into

: Detection of selection footprints provides insight into the evolution process and the underlying mechanisms controlling the phenotypic diversity of traits that have been exposed to selection. Selection focused on certain characters, mapping certain genomic regions often shows a loss of genetic diversity with an increased level of homozygosity. Therefore, the runs of homozygosity (ROHs), homozygosity by descent (HBD), and effective population size (Ne) are effective tools for exploring the genetic diversity, understanding the demographic history, foretelling the signature of directional selection, and improving the breeding strategies to use and conserve genetic resources. We characterized the ROH, HBD, Ne, and signature of selection of six Chinese goat populations using single nucleotide polymorphism (SNP) 50K Illumina beadchips. Our results show an inverse relationship between the length and frequency of ROH. A long ROH length, higher level of inbreeding, long HBD segment, and smaller Ne in Guangfeng (GF) goats suggested intensive selection pressure and recent inbreeding in this breed. We identified six reproduction-related genes within the genomic regions with a high ROH frequency, of which two genes overlapped with a putative selection signature. The estimated pair-wise genetic differentiation (FST) among the populations is 9.60% and the inter- and intra-population molecular variations are 9.68% and 89.6%, respectively, indicating low to moderate genetic differentiation. Our selection signatures analysis revealed 54 loci harboring 86 putative candidate genes, with a strong signature of selection. Further analysis showed that several candidate genes, including MARF1, SYCP2, TMEM200C, SF1, ADCY1, and BMP5, are involved in goat fecundity. We identified 11 candidate genes by using cross-population extended haplotype homozygosity (XP-EHH) estimates, of which MARF1 and SF1 are under strong positive selection, as they are differentiated in high and low reproduction groups according to the three approaches used. Gene ontology enrichment analysis revealed that different biological pathways could be involved in the variation of fecundity in female goats. This study provides a new insight into the ROHs patterns for maintenance of within breed diversity and suggests a role of positive selection for genetic variation influencing fecundity in Chinese goat.

scholarly journals Discovery and comparative genomic analysis of elk circovirus (ElkCV), a novel circovirus species and the first reported from a cervid host

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mathew Fisher ◽  
Thomas M. R. Harrison ◽  
Michelle Nebroski ◽  
Peter Kruczkiewicz ◽  
Jamie L. Rothenburger ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Genomic Analysis ◽  
Rocky Mountain ◽  
International Committee ◽  
Comparative Genomic Analysis ◽  
Nucleotide Identity ◽  
Comparative Genomic ◽  
Stem Loop ◽  
Genome Wide ◽  
Replication Region

Abstract The complete genome sequence of a novel circovirus (elk circovirus (ElkCV) Banff/2019) was determined via high throughput sequencing of liver tissue from a euthanized Rocky Mountain elk (Cervus canadensis nelsoni) from Alberta, Canada. The genome is circular and 1,787 nucleotides long, with two major ORFs encoding predicted proteins. Comparative genomic analysis to 4,164 publicly available complete and near complete circovirus genomes showed that ElkCV shares approximately 65% pairwise genome-wide nucleotide identity with the most closely related circovirus species, porcine circoviruses (PCV) 1 and 2 and bat-associated circovirus (BatACV) 11. ElkCV features a stem-loop within the origin of replication region characteristic of circoviruses. However, it differs from those found in PCV1, PCV2 and BatACV11 since it has a longer stem and contains hexamer repeats that overlap the stem in opposing orientations. Interestingly, stem-loop structures of similar length featuring repeats in a similar position and orientation are also seen in some avian circoviruses. Based on the demarcation threshold established by the International Committee on Taxonomy of Viruses (ICTV) for members of Circoviridae (80% pairwise genome-wide nucleotide identity), ElkCV represents a novel species and is the first complete circovirus genome reported from a cervid host.

scholarly journals Associative Overdominance and Negative Epistasis Shape Genome-Wide Ancestry Landscape in Supplemented Fish Populations

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 524
Author(s):  
Maeva Leitwein ◽  
Hugo Cayuela ◽  
Louis Bernatchez
Keyword(s):  
Genetic Diversity ◽  
Genetic Drift ◽  
Recombination Rate ◽  
Management Strategies ◽  
Population Level ◽  
Negative Effects ◽  
Isolated Populations ◽  
Positive Effects ◽  
Genome Wide ◽  
Negative Epistasis

The interplay between recombination rate, genetic drift and selection modulates variation in genome-wide ancestry. Understanding the selective processes at play is of prime importance toward predicting potential beneficial or negative effects of supplementation with domestic strains (i.e., human-introduced strains). In a system of lacustrine populations supplemented with a single domestic strain, we documented how population genetic diversity and stocking intensity produced lake-specific patterns of domestic ancestry by taking the species’ local recombination rate into consideration. We used 552 Brook Charr (Salvelinus fontinalis) from 22 small lacustrine populations, genotyped at ~32,400 mapped SNPs. We observed highly variable patterns of domestic ancestry between each of the 22 populations without any consistency in introgression patterns of the domestic ancestry. Our results suggest that such lake-specific ancestry patterns were mainly due to variable associative overdominance (AOD) effects among populations (i.e., potential positive effects due to the masking of possible deleterious alleles in low recombining regions). Signatures of AOD effects were also emphasized by highly variable patterns of genetic diversity among and within lakes, potentially driven by predominant genetic drift in those small isolated populations. Local negative effects such as negative epistasis (i.e., potential genetic incompatibilities between the native and the introduced population) potentially reflecting precursory signs of outbreeding depression were also observed at a chromosomal scale. Consequently, in order to improve conservation practices and management strategies, it became necessary to assess the consequences of supplementation at the population level by taking into account both genetic diversity and stocking intensity when available.

scholarly journals Linkage disequilibrium and within-breed genetic diversity in Iranian Zandi sheep

2019 ◽  
Vol 62 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Seyed Mohammad Ghoreishifar ◽  
Hossein Moradi-Shahrbabak ◽  
Nahid Parna ◽  
Pourya Davoudi ◽  
Majid Khansefid
Keyword(s):  
Genetic Diversity ◽  
Linkage Disequilibrium ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
Effective Population ◽  
High Genetic Diversity ◽  
Single Nucleotide ◽  
Genome Wide ◽  
Snp Panel ◽  
Zandi Sheep

Abstract. This research aimed to measure the extent of linkage disequilibrium (LD), effective population size (Ne), and runs of homozygosity (ROHs) in one of the major Iranian sheep breeds (Zandi) using 96 samples genotyped with Illumina Ovine SNP50 BeadChip. The amount of LD (r2) for single-nucleotide polymorphism (SNP) pairs in short distances (10–20 kb) was 0.21±0.25 but rapidly decreased to 0.10±0.16 by increasing the distance between SNP pairs (40–60 kb). The Ne of Zandi sheep in past (approximately 3500 generations ago) and recent (five generations ago) populations was estimated to be 6475 and 122, respectively. The ROH-based inbreeding was 0.023. We found 558 ROH regions, of which 37 % were relatively long (> 10 Mb). Compared with the rate of LD reduction in other species (e.g., cattle and pigs), in Zandi, it was reduced more rapidly by increasing the distance between SNP pairs. According to the LD pattern and high genetic diversity of Zandi sheep, we need to use an SNP panel with a higher density than Illumina Ovine SNP50 BeadChip for genomic selection and genome-wide association studies in this breed.

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