scholarly journals “Ghost Introgression” As a Cause of Deep Mitochondrial Divergence in a Bird Species Complex

2019 ◽  
Vol 36 (11) ◽  
pp. 2375-2386 ◽  
Author(s):  
Dezhi Zhang ◽  
Linfang Tang ◽  
Yalin Cheng ◽  
Yan Hao ◽  
Ying Xiong ◽  
...  
Keyword(s):  
Bird Species ◽  
Nuclear Genome ◽  
Distinct Species ◽  
Comparative Genomic ◽  
Genetic Introgression ◽  
Effective Population ◽  
Westward Expansion ◽  
Whole Genomes ◽  
Linked Selection ◽  
Two Populations

Abstract In the absence of nuclear-genomic differentiation between two populations, deep mitochondrial divergence (DMD) is a form of mito-nuclear discordance. Such instances of DMD are rare and might variably be explained by unusual cases of female-linked selection, by male-biased dispersal, by “speciation reversal” or by mitochondrial capture through genetic introgression. Here, we analyze DMD in an Asian Phylloscopus leaf warbler (Aves: Phylloscopidae) complex. Bioacoustic, morphological, and genomic data demonstrate close similarity between the taxa affinis and occisinensis, even though DMD previously led to their classification as two distinct species. Using population genomic and comparative genomic methods on 45 whole genomes, including historical reconstructions of effective population size, genomic peaks of differentiation and genomic linkage, we infer that the form affinis is likely the product of a westward expansion in which it replaced a now-extinct congener that was the donor of its mtDNA and small portions of its nuclear genome. This study provides strong evidence of “ghost introgression” as the cause of DMD, and we suggest that “ghost introgression” may be a widely overlooked phenomenon in nature.

scholarly journals Ancient Hybridization with an Unknown Population Facilitated High-Altitude Adaptation of Canids

2020 ◽  
Vol 37 (9) ◽  
pp. 2616-2629 ◽  
Author(s):  
Ming-Shan Wang ◽  
Sheng Wang ◽  
Yan Li ◽  
Yadvendradev Jhala ◽  
Mukesh Thakur ◽  
...  
Keyword(s):  
High Altitude ◽  
Evolutionary History ◽  
Nuclear Genome ◽  
Genetic Introgression ◽  
Data Set ◽  
Whole Genomes ◽  
Ancient Lineage ◽  
History Of ◽  
Evolutionary Trajectories ◽  
Altitude Adaptation

Abstract Genetic introgression not only provides material for adaptive evolution but also confounds our understanding of evolutionary history. This is particularly true for canids, a species complex in which genome sequencing and analysis has revealed a complex history of admixture and introgression. Here, we sequence 19 new whole genomes from high-altitude Tibetan and Himalayan wolves and dogs and combine these into a larger data set of 166 whole canid genomes. Using these data, we explore the evolutionary history and adaptation of these and other canid lineages. We find that Tibetan and Himalayan wolves are closely related to each other, and that ∼39% of their nuclear genome is derived from an as-yet-unrecognized wolf-like lineage that is deeply diverged from living Holarctic wolves and dogs. The EPAS1 haplotype, which is present at high frequencies in Tibetan dog breeds and wolves and confers an adaptive advantage to animals living at high altitudes, was probably derived from this ancient lineage. Our study underscores the complexity of canid evolution and demonstrates how admixture and introgression can shape the evolutionary trajectories of species.

scholarly journals Genomic architecture controls spatial structuring in Amazonian birds

2021 ◽  
Author(s):  
Gregory Thom ◽  
Lucas Rocha Moreira ◽  
Romina Batista ◽  
Marcelo Gehara ◽  
Alexandre Aleixo ◽  
...  
Keyword(s):  
Gene Flow ◽  
Life Histories ◽  
Demographic History ◽  
Bird Species ◽  
Comparative Genomic ◽  
Genomic Architecture ◽  
Branching Model ◽  
Whole Genomes ◽  
Genomic Approach ◽  
Neutral Models

Large rivers are ubiquitously invoked to explain the distributional limits and speciation of the Amazon Basin's mega-diversity. However, inferences on the spatial and temporal origins of Amazonian species have narrowly focused on evolutionary neutral models, ignoring the potential role of natural selection and intrinsic genomic processes known to produce heterogeneity in differentiation across the genome. To test how these factors may influence evolutionary inferences across multiple taxa, we sequenced whole genomes of populations for three bird species that co-occur in southeastern Amazonian and exhibit different life histories linked to their propensity to maintain gene flow across the landscape. We found that phylogenetic relationships within species and demographic parameters varied across the genome in predictable ways. Genetic diversity was positively associated with recombination rate and negatively associated with the species tree topology weight. Gene flow was less pervasive in regions of low recombination, making these windows more suitable for commonly used phylogenetic methods that assume a bifurcating-branching model. To corroborate that these associations were attributable to selection, we modeled the signature of adaptive alleles across the genome taking demographic history into account, and found that on average 31.6 percent of the genome showed high probability for patterns consistent with selective sweeps and linked selection directly affecting the estimation of evolutionary parameters. By implementing a comparative genomic approach we were able to disentangle the effects of intrinsic genomic characteristics and selection from the neutral processes and show how speciation hypotheses are sensitive to genomic architecture.

scholarly journals Similar efficacies of selection shape mitochondrial and nuclear genes in Drosophila melanogaster and Homo sapiens

2014 ◽  
Author(s):  
Brandon S. Cooper ◽  
Chad Burrus ◽  
Chao Ji ◽  
Matthew W. Hahn ◽  
Kristi L. Montooth
Keyword(s):  
Drosophila Melanogaster ◽  
Homo Sapiens ◽  
Nuclear Genome ◽  
Nuclear Data ◽  
Nuclear Genes ◽  
Small Samples ◽  
Published Data ◽  
Effective Population ◽  
Synonymous Polymorphism ◽  
Linked Selection

Deleterious mutations contribute to polymorphism even when selection effectively prevents their fixation. The efficacy of selection in removing deleterious mitochondrial mutations from populations depends on the effective population size (Ne) of the mtDNA, and the degree to which a lack of recombination magnifies the effects of linked selection. Using complete mitochondrial genomes from Drosophila melanogaster and nuclear data available from the same samples, we re-examine the hypothesis that non-recombining animal mtDNA harbor an excess of deleterious polymorphisms relative to the nuclear genome. We find no evidence of recombination in the mitochondrial genome, and the much-reduced level of mitochondrial synonymous polymorphism relative to nuclear genes is consistent with a reduction in Ne. Nevertheless, we find that the neutrality index (NI), a measure of the excess of nonsynonymous polymorphism relative to the neutral expectation, is not significantly different between mitochondrial and nuclear loci. Reanalysis of published data from Homo sapiens reveals the same lack of a difference between the two genomes, though small samples in previous studies had suggested a strong difference in both species. Thus, despite a smaller Ne, mitochondrial loci of both flies and humans appear to experience similar efficacies of selection as do loci in the recombining nuclear genome.

scholarly journals Low Nucleotide Diversity in Chimpanzees and Bonobos

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1511-1518 ◽  
Author(s):  
Ning Yu ◽  
Michael I Jensen-Seaman ◽  
Leona Chemnick ◽  
Judith R Kidd ◽  
Amos S Deinard ◽  
...  
Keyword(s):  
Nucleotide Diversity ◽  
Nuclear Dna ◽  
Demographic History ◽  
Nuclear Genome ◽  
Limited Data ◽  
Effective Population ◽  
East Central ◽  
Dna Diversity ◽  
History Of ◽  
Mtdna Diversity

Abstract Comparison of the levels of nucleotide diversity in humans and apes may provide much insight into the mechanisms of maintenance of DNA polymorphism and the demographic history of these organisms. In the past, abundant mitochondrial DNA (mtDNA) polymorphism data indicated that nucleotide diversity (π) is more than threefold higher in chimpanzees than in humans. Furthermore, it has recently been claimed, on the basis of limited data, that this is also true for nuclear DNA. In this study we sequenced 50 noncoding, nonrepetitive DNA segments randomly chosen from the nuclear genome in 9 bonobos and 17 chimpanzees. Surprisingly, the π value for bonobos is only 0.078%, even somewhat lower than that (0.088%) for humans for the same 50 segments. The π values are 0.092, 0.130, and 0.082% for East, Central, and West African chimpanzees, respectively, and 0.132% for all chimpanzees. These values are similar to or at most only 1.5 times higher than that for humans. The much larger difference in mtDNA diversity than in nuclear DNA diversity between humans and chimpanzees is puzzling. We speculate that it is due mainly to a reduction in effective population size (Ne) in the human lineage after the human-chimpanzee divergence, because a reduction in Ne has a stronger effect on mtDNA diversity than on nuclear DNA diversity.

scholarly journals Low genetic diversity in the endangered Taxus yunnanensis following a population bottleneck, a low effective population size and increased inbreeding

2016 ◽  
Vol 65 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Y. C. Miao ◽  
Z. J. Zhang ◽  
J. R. Su
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Effective Population Size ◽  
Spatial Genetic Structure ◽  
Population Bottleneck ◽  
Effective Population ◽  
Taxus Yunnanensis ◽  
Low Genetic Diversity ◽  
Two Populations

Abstract Taxus yunnanensis, which is an endangered tree that is considered valuable because it contains the effective natural anticancer metabolite taxol and heteropolysaccharides, has long suffered from severe habitat fragmentation. In this study, the levels of genetic diversity in two populations of 136 individuals were analyzed based on eleven polymorphic microsatellite loci. Our results suggested that these two populations were characterized by low genetic diversity (NE = 2.303/2.557; HO = 0.168/0.142; HE = 0.453/0.517), a population bottleneck, a low effective population size (Ne = 7/9), a high level of inbreeding (FIS = 0.596/0.702), and a weak, but significant spatial genetic structure (Sp = 0.001, b = −0.001*). Habitat fragmentation, seed shadow overlap and limited seed and pollen dispersal and potential selfing may have contributed to the observed gene tic structure. The results of the present study will enable development of practical conservation measures to effectively conserve the valuable genetic resources of this endangered plant.

scholarly journals The genomic landscape of recombination rate variation in Chlamydomonas reinhardtii reveals a pronounced effect of linked selection

2018 ◽  
Author(s):  
Ahmed R. Hasan ◽  
Rob W. Ness
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Recombination Rate ◽  
Natural Populations ◽  
Gc Content ◽  
Sexual Cycle ◽  
Rate Variation ◽  
Effective Population ◽  
Entire Genome ◽  
Recombination Rate Variation ◽  
Linked Selection

AbstractRecombination confers a major evolutionary advantage by breaking up linkage disequilibrium (LD) between harmful and beneficial mutations and facilitating selection. Here, we use genome-wide patterns of LD to infer fine-scale recombination rate variation in the genome of the model green alga Chlamydomonas reinhardtii and estimate rates of LD decay across the entire genome. We observe recombination rate variation of up to two orders of magnitude, finding evidence of recombination hotspots playing a role in the genome. Recombination rate is highest just upstream of genic regions, suggesting the preferential targeting of recombination breakpoints in promoter regions. Furthermore, we observe a positive correlation between GC content and recombination rate, suggesting a role for GC-biased gene conversion or selection on base composition within the GC-rich genome of C. reinhardtii. We also find a positive relationship between nucleotide diversity and recombination, consistent with widespread influence of linked selection in the genome. Finally, we use estimates of the effective rate of recombination to calculate the rate of sex that occurs in natural populations of this important model microbe, estimating a sexual cycle roughly every 770 generations. We argue that the relatively infrequent rate of sex and large effective population size creates an population genetic environment that increases the influence of linked selection on the genome.

scholarly journals ddRAD Sequencing Sheds Light on Low Interspecific and High Intraspecific mtDNA Divergences in Two Groups of Caddisflies

2021 ◽  
Vol 5 (5) ◽  
Author(s):  
Juha Salokannel ◽  
Kyung Min Lee ◽  
Aki Rinne ◽  
Marko Mutanen
Keyword(s):  
Dna Barcoding ◽  
Large Scale ◽  
Dna Barcode ◽  
Nuclear Genome ◽  
Distinct Species ◽  
Present Species ◽  
Cryptic Diversity ◽  
Weak Support ◽  
Genomic Scale ◽  
Group Species

Abstract Large-scale global efforts on DNA barcoding have repeatedly revealed unexpected patterns of variability in mtDNA, including deep intraspecific divergences and haplotype sharing between species. Understanding the evolutionary causes behind these patterns calls for insights from the nuclear genome. While building a near-complete DNA barcode library of Finnish caddisflies, a case of barcode-sharing and some cases of deep intraspecific divergences were observed. In this study, the Apatania zonella (Zetterstedt, 1840) group and three Limnephilus Leach, 1815 species were studied using double digest RAD sequencing (ddRAD-seq), morphology, and DNA barcoding. The results support the present species boundaries in the A. zonella group species. A morphologically distinct but mitogenetically nondistinct taxon related to parthenogenetic Apatania hispida (Forsslund, 1930) got only weak support for its validity as a distinct species. The morphology and genomic-scale data do not indicate cryptic diversity in any of the three Limnephilus species despite the observed deep intraspecific divergences in DNA barcodes. This demonstrates that polymorphism in mtDNA may not reflect cryptic diversity, but mitonuclear discordance due to other evolutionary causes.

scholarly journals Eusociality Shapes Convergent Patterns of Molecular Evolution across Mitochondrial Genomes of Snapping Shrimps

2020 ◽  
Author(s):  
Solomon T C Chak ◽  
Juan Antonio Baeza ◽  
Phillip Barden
Keyword(s):  
Molecular Evolution ◽  
Genome Evolution ◽  
Purifying Selection ◽  
Synonymous Substitution ◽  
Mitochondrial Genomes ◽  
Comparative Genomic ◽  
Effective Population ◽  
Protein Coding ◽  
Marine Realm ◽  
Snapping Shrimps

Abstract Eusociality is a highly conspicuous and ecologically impactful behavioral syndrome that has evolved independently across multiple animal lineages. So far, comparative genomic analyses of advanced sociality have been mostly limited to insects. Here, we study the only clade of animals known to exhibit eusociality in the marine realm—lineages of socially diverse snapping shrimps in the genus Synalpheus. To investigate the molecular impact of sociality, we assembled the mitochondrial genomes of eight Synalpheus species that represent three independent origins of eusociality and analyzed patterns of molecular evolution in protein-coding genes. Synonymous substitution rates are lower and potential signals of relaxed purifying selection are higher in eusocial relative to noneusocial taxa. Our results suggest that mitochondrial genome evolution was shaped by eusociality-linked traits—extended generation times and reduced effective population sizes that are hallmarks of advanced animal societies. This is the first direct evidence of eusociality impacting genome evolution in marine taxa. Our results also strongly support the idea that eusociality can shape genome evolution through profound changes in life history and demography.

scholarly journals Divergent selection and genetic introgression shape the genome landscape of heterosis in hybrid rice

2020 ◽  
Vol 117 (9) ◽  
pp. 4623-4631 ◽  
Author(s):  
Zechuan Lin ◽  
Peng Qin ◽  
Xuanwen Zhang ◽  
Chenjian Fu ◽  
Hanchao Deng ◽  
...  
Keyword(s):  
Hybrid Rice ◽  
Field Trials ◽  
Hybrid Breeding ◽  
Genetic Introgression ◽  
Rice Varieties ◽  
Rice Landraces ◽  
Rice Hybrid ◽  
Negative Effect ◽  
Two Populations ◽  
Positive Effect

The successful application of heterosis in hybrid rice has dramatically improved rice productivity, but the genetic mechanism for heterosis in the hybrid rice remains unclear. In this study, we generated two populations of rice F1hybrids with present-day commercial hybrid parents, genotyped the parents with 50k SNP chip and genome resequencing, and recorded the phenotype of ∼2,000 hybrids at three field trials. By integrating these data with the collected genotypes of ∼4,200 rice landraces and improved varieties that were reported previously, we found that the male and female parents have different levels of genome introgressions from other rice subpopulations, includingindica,aus, andjaponica, therefore shaping heterotic loci in the hybrids. Among the introgressed exogenous genome, we found that heterotic loci, includingGhd8/DTH8,Gn1a, andIPA1existed in wild rice, but were significantly divergently selected among the rice subpopulations, suggesting these loci were subject to environmental adaptation. During modern rice hybrid breeding, heterotic loci were further selected by removing loci with negative effect and fixing loci with positive effect and pyramid breeding. Our results provide insight into the genetic basis underlying the heterosis of elite hybrid rice varieties, which could facilitate a better understanding of heterosis and rice hybrid breeding.

Sign in / Sign up

Export Citation Format

Share Document