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Long-read sequencing data, particularly those derived from the Oxford Nanopore sequencing platform, tend to exhibit high error rates. Here, we present NextDenovo, an efficient error correction and assembly tool for noisy long reads, which achieves a high level of accuracy in genome assembly. We apply NextDenovo to assemble 35 diverse human genomes from around the world using Nanopore long-read data. These genomes allow us to identify the landscape of segmental duplication and gene copy number variation in modern human populations. The use of NextDenovo should pave the way for population-scale long-read assembly using Nanopore long-read data.

The homing pigeon was selectively bred from the domestic pigeon for a homing ability over long distances, a very fascinating but complex behavioral trait. Here, we generate a total of 95 whole genomes from diverse pigeon breeds. Comparing the genomes from the homing pigeon population with those from other breeds identifies candidate positively selected genes, including many genes involved in the central nervous system, particularly spatial learning and memory such as LRP8. Expression profiling reveals many neuronal genes displaying differential expression in the hippocampus, which is the key organ for memory and navigation and exhibits significantly larger size in the homing pigeon. In addition, we uncover a candidate gene GSR (encoding glutathione-disulfide reductase) experiencing positive selection in the homing pigeon. Expression profiling finds that GSR is highly expressed in the wattle and visual pigment cell layer, and displays increased expression levels in the homing pigeon. In vitro, a magnetic field stimulates increases in calcium ion concentration in cells expressing pigeon GSR. These findings support the importance of the hippocampus (functioning in spatial memory and navigation) for homing ability, and the potential involvement of GSR in pigeon magnetoreception.

Elucidating the closest living relatives of extant primates is essential for fully understanding important biological processes related to the genomic and phenotypic evolution of primates, especially of humans. However, the phylogenetic placement of these primate relatives remains controversial, with three primary hypotheses currently espoused based on morphological and molecular evidence. In the present study, we used two algorithms to analyze differently partitioned genomic datasets consisting of 45.4 Mb of conserved non-coding elements and 393 kb of concatenated coding sequences to test these hypotheses. We assessed different genomic histories and compared with other molecular studies found solid support for colugos being the closest living relatives of primates. Our phylogeny showed Cercopithecinae to have low levels of nucleotide divergence, especially for Papionini, and gibbons to have a high rate of divergence. The MCMCtree comprehensively updated divergence dates of early evolution of Primatomorpha and Primates.

Comprehensive biodiversity assessment of moths in Nigeria rely greatly on accurate species identification. While most of the Nigerian moths are identified effortlessly using their morphological traits, some taxa are morphologically indistinguishable, which makes it difficult for taxon diagnosis. We investigated the efficiency of the DNA barcode, a fragment of the mitochondrial Cytochrome C oxidase subunit I, as a tool for the identification of Nigerian moths. We barcoded 152 individuals comprising 18 morphospecies collected from one of the remaining and threatened rainforest blocks of Nigeria – the Cross River National Park. Phenetic neighbor-joining tree and phylogenetic Maximum Likelihood approach were employed for the molecular-based species identification. Results showed that DNA barcodes enabled species-level identification of most of the individuals collected from the Park. Additionally, DNA barcoding unraveled the presence of at least six potential new and yet undescribed species—Amnemopsyche sp., Arctia sp., Deinypena sp., Hodebertia sp., Otroeda sp., and Palpita sp. The phylogenetic Maximum Likelihood using the combined dataset of all the newly assembled sequences from Nigeria showed that all species formed unique clades. The phylogenetic analyses provided evidence of population divergence in Euchromia lethe, Nyctemera leuconoe, and Deinypena lacista. This study thus illustrates the efficacy of DNA barcoding for species identification and discovery of potential new species, which demonstrates its relevance in biodiversity documentation of Nigerian moths. Future work should, therefore, extend to the creation of an exhaustive DNA barcode reference library comprising all species of moths from Nigeria to have a comprehensive insight on the diversity of moths in the country. Finally, we propose integrated taxonomic methods that would combine morphological, ecological, and molecular data in the identification and diversity studies of moths in Nigeria.

Guenons (tribe Cercopithecini) are the most widely distributed nonhuman primate in the tropical forest belt of Africa and show considerable phenotypic, taxonomic, and ecological diversity. However, genomic information for most species within this group is still lacking. Here, we present a high-quality de novo genome (total 2.90 Gb, contig N50 equal to 22.7 Mb) of the mona monkey (Cercopithecus mona), together with genome resequencing data of 13 individuals sampled across Nigeria. Our results showed differentiation between populations from East and West of the Niger River ∼84 ka and potential ancient introgression in the East population from other mona group species. The PTPRK, FRAS1, BNC2, and EDN3 genes related to pigmentation displayed signals of introgression in the East population. Genomic scans suggest that immunity genes such as AKT3 and IL13 (possibly involved in simian immunodeficiency virus defense), and G6PD, a gene involved in malaria resistance, are under positive natural selection. Our study gives insights into differentiation, natural selection, and introgression in guenons.

Accurate identification of species is a prerequisite for successful biodiversity management and further genetic studies. Species identification techniques often require both morphological diagnostics and molecular tools, such as DNA barcoding, for correct identification. In particular, the use of the subunit I of the mitochondrial cytochrome c oxidase (COI) gene for DNA barcoding has proven useful in species identification for insects. However, to date, no studies have been carried out on the DNA barcoding of Nigerian butterflies. We evaluated the utility of DNA barcoding applied for the first time to 735 butterfly specimens from southern Nigeria. In total, 699 DNA barcodes, resulting in a record of 116 species belonging to 57 genera, were generated. Our study sample comprised 807 DNA barcodes based on sequences generated from our current study and 108 others retrieved from BOLD. Different molecular analyses, including genetic distance-based evaluation (Neighbor-Joining, Maximum Likelihood and Bayesian trees) and species delimitation tests (TaxonDNA, Automated Barcode Gap Discovery, General Mixed Yule-Coalescent, and Bayesian Poisson Tree Processes) were performed to accurately identify and delineate species. The genetic distance-based analyses resulted in 163 well-separated clusters consisting of 147 described and 16 unidentified species. Our findings indicate that about 90.20% of the butterfly species were explicitly discriminated using DNA barcodes. Also, our field collections reported the first country records of ten butterfly species— Acraea serena , Amauris cf. dannfelti , Aterica galena extensa , Axione tjoane rubescens , Charaxes galleyanus , Papilio lormieri lormeri , Pentila alba , Precis actia , Precis tugela, and Tagiades flesus . Further, DNA barcodes revealed a high mitochondrial intraspecific divergence of more than 3% in Bicyclus vulgaris vulgaris and Colotis evagore . Furthermore, our result revealed an overall high haplotype (gene) diversity (0.9764), suggesting that DNA barcoding can provide information at a population level for Nigerian butterflies. The present study confirms the efficiency of DNA barcoding for identifying butterflies from Nigeria. To gain a better understanding of regional variation in DNA barcodes of this biogeographically complex area, future work should expand the DNA barcode reference library to include all butterfly species from Nigeria as well as surrounding countries. Also, further studies, involving relevant genetic and eco-morphological datasets, are required to understand processes governing mitochondrial intraspecific divergences reported in some species complexes.

Long read sequencing data, particularly those derived from the Oxford Nanopore (ONT) sequencing platform, tend to exhibit a high error rate. Here, we present NextDenovo, a highly efficient error correction and assembly tool for noisy long reads, which achieves a high level of accuracy in genome assembly. NextDenovo can rapidly correct reads; these corrected reads contain fewer errors than other comparable tools and are characterized by fewer chimeric alignments. We applied NextDenovo to the assembly of high quality reference genomes of 35 diverse humans from across the world using ONT Nanopore long read sequencing data. Based on these de novo genome assemblies, we were able to identify the landscape of segmental duplications and gene copy number variation in the modern human population. The use of the NextDenovo program should pave the way for population-scale long-read assembly, thereby facilitating the construction of human pan-genomes, using Nanopore long read sequencing data.Competing Interest StatementThe authors have declared no competing interest.Footnotes* https://github.com/Nextomics/NextDenovo