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Ohadi M, Arabfard M, Khamse S, Alizadeh S, Vafadar S, Bayat H, Tajeddin N, Maddi AMA, Delbari A, Khorram Khorshid HR. Novel crossover and recombination hotspots massively spread across primate genomes. Biol Direct 2024; 19:70. [PMID: 39169390 PMCID: PMC11340189 DOI: 10.1186/s13062-024-00508-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 07/29/2024] [Indexed: 08/23/2024] Open
Abstract
BACKGROUND The recombination landscape and subsequent natural selection have vast consequences forevolution and speciation. However, most of the crossover and recombination hotspots are yet to be discovered. We previously reported the relevance of C and G trinucleotide two-repeat units (CG-TTUs) in crossovers and recombination. METHODS On a genome-wide scale, here we mapped all combinations of A and T trinucleotide two-repeat units (AT-TTUs) in human, consisting of AATAAT, ATAATA, ATTATT, TTATTA, TATTAT, and TAATAA. We also compared a number of the colonies formed by the AT-TTUs (distance between consecutive AT-TTUs < 500 bp) in several other primates and mouse. RESULTS We found that the majority of the AT-TTUs (> 96%) resided in approximately 1.4 million colonies, spread throughout the human genome. In comparison to the CG-TTU colonies, the AT-TTU colonies were significantly more abundant and larger in size. Pure units and overlapping units of the pure units were readily detectable in the same colonies, signifying that the units were the sites of unequal crossover. We discovered dynamic sharedness of several of the colonies across the primate species studied, which mainly reached maximum complexity and size in human. CONCLUSIONS We report novel crossover and recombination hotspots of the finest molecular resolution, massively spread and shared across the genomes of human and several other primates. With respect to crossovers and recombination, these genomes are far more dynamic than previously envisioned.
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Affiliation(s)
- Mina Ohadi
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
| | - Masoud Arabfard
- Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Safoura Khamse
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Samira Alizadeh
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Sara Vafadar
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hadi Bayat
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
- Biochemical Neuroendocrinology, Montreal Clinical and Research Institute (IRCM, affiliated to the McGill University, Montreal, QC, H2W 1R7, Canada
| | - Nahid Tajeddin
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
- Department of Biology, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Ali M A Maddi
- Laboratory of Complex Biological Systems and Bioinformatics (CBB), Department of Bioinformatics, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - Ahmad Delbari
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hamid R Khorram Khorshid
- Personalized Medicine and Genometabolomics Research Center, Hope Generation Foundation, Tehran, Iran
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Parée T, Noble L, Ferreira Gonçalves J, Teotónio H. rec-1 loss of function increases recombination in the central gene clusters at the expense of autosomal pairing centers. Genetics 2024; 226:iyad205. [PMID: 38001364 DOI: 10.1093/genetics/iyad205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/03/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
Meiotic control of crossover (CO) number and position is critical for homologous chromosome segregation and organismal fertility, recombination of parental genotypes, and the generation of novel genetic combinations. We here characterize the recombination rate landscape of a rec-1 loss of function modifier of CO position in Caenorhabditis elegans, one of the first ever modifiers discovered. By averaging CO position across hermaphrodite and male meioses and by genotyping 203 single-nucleotide variants covering about 95% of the genome, we find that the characteristic chromosomal arm-center recombination rate domain structure is lost in the loss of function rec-1 mutant. The rec-1 loss of function mutant smooths the recombination rate landscape but is insufficient to eliminate the nonuniform position of CO. Lower recombination rates in the rec-1 mutant are particularly found in the autosomal arm domains containing the pairing centers. We further find that the rec-1 mutant is of little consequence for organismal fertility and egg viability and thus for rates of autosomal nondisjunction. It nonetheless increases X chromosome nondisjunction rates and thus male appearance. Our findings question the maintenance of recombination rate heritability and genetic diversity among C. elegans natural populations, and they further suggest that manipulating genetic modifiers of CO position will help find quantitative trait loci located in low-recombining genomic regions normally refractory to discovery.
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Affiliation(s)
- Tom Parée
- Institut de Biologie de l'École Normale Supérieure, CNRS UMR, 8197, Inserm U1024, PSL Research University, Paris F-75005, France
| | - Luke Noble
- Institut de Biologie de l'École Normale Supérieure, CNRS UMR, 8197, Inserm U1024, PSL Research University, Paris F-75005, France
- EnviroDNA, 95 Albert St., Brunswick, Victoria 3065, Australia
| | - João Ferreira Gonçalves
- Institut de Biologie de l'École Normale Supérieure, CNRS UMR, 8197, Inserm U1024, PSL Research University, Paris F-75005, France
| | - Henrique Teotónio
- Institut de Biologie de l'École Normale Supérieure, CNRS UMR, 8197, Inserm U1024, PSL Research University, Paris F-75005, France
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3
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Falcon F, Tanaka EM, Rodriguez-Terrones D. Transposon waves at the water-to-land transition. Curr Opin Genet Dev 2023; 81:102059. [PMID: 37343338 DOI: 10.1016/j.gde.2023.102059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023]
Abstract
The major transitions in vertebrate evolution are associated with significant genomic reorganizations. In contrast to the evolutionary processes that occurred at the origin of vertebrates or prior to the radiation of teleost fishes, no whole-genome duplication events occurred during the water-to-land transition, and it remains an open question how did genome dynamics contribute to this prominent evolutionary event. Indeed, the recent sequencing of sarcopterygian and amphibian genomes has revealed that the extant lineages immediately preceding and succeeding this transition harbor an exceptional number of transposable elements and it is tempting to speculate that these sequences might have catalyzed the adaptations that enabled vertebrates to venture into land. Here, we review the genome dynamics associated with the major transitions in vertebrate evolution and discuss how the highly repetitive genomic landscapes revealed by recent efforts to characterize the genomes of amphibians and sarcopterygians argue for turbulent genome dynamics occurring before the water-to-land transition and possibly enabling it.
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Affiliation(s)
- Francisco Falcon
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria. https://twitter.com/@FcoJFalcon
| | - Elly M Tanaka
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria.
| | - Diego Rodriguez-Terrones
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria.
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4
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Zhao P, Peng C, Fang L, Wang Z, Liu GE. Taming transposable elements in livestock and poultry: a review of their roles and applications. Genet Sel Evol 2023; 55:50. [PMID: 37479995 PMCID: PMC10362595 DOI: 10.1186/s12711-023-00821-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 06/30/2023] [Indexed: 07/23/2023] Open
Abstract
Livestock and poultry play a significant role in human nutrition by converting agricultural by-products into high-quality proteins. To meet the growing demand for safe animal protein, genetic improvement of livestock must be done sustainably while minimizing negative environmental impacts. Transposable elements (TE) are important components of livestock and poultry genomes, contributing to their genetic diversity, chromatin states, gene regulatory networks, and complex traits of economic value. However, compared to other species, research on TE in livestock and poultry is still in its early stages. In this review, we analyze 72 studies published in the past 20 years, summarize the TE composition in livestock and poultry genomes, and focus on their potential roles in functional genomics. We also discuss bioinformatic tools and strategies for integrating multi-omics data with TE, and explore future directions, feasibility, and challenges of TE research in livestock and poultry. In addition, we suggest strategies to apply TE in basic biological research and animal breeding. Our goal is to provide a new perspective on the importance of TE in livestock and poultry genomes.
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Affiliation(s)
- Pengju Zhao
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Chen Peng
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Lingzhao Fang
- Center for Quantitative Genetics and Genomics, Aarhus University, 8000, Aarhus, Denmark.
| | - Zhengguang Wang
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China.
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China.
| | - George E Liu
- Animal Genomics and Improvement Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD, 20705, USA.
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5
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van Dijk A, Guabiraba R, Bailleul G, Schouler C, Haagsman HP, Lalmanach AC. Evolutionary diversification of defensins and cathelicidins in birds and primates. Mol Immunol 2023; 157:53-69. [PMID: 36996595 DOI: 10.1016/j.molimm.2023.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/09/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023]
Abstract
Divergent evolution for more than 310 million years has resulted in an avian immune system that is complex and more compact than that of primates, sharing much of its structure and functions. Not surprisingly, well conserved ancient host defense molecules, such as defensins and cathelicidins, have diversified over time. In this review, we describe how evolution influenced the host defense peptides repertoire, its distribution, and the relationship between structure and biological functions. Marked features of primate and avian HDPs are linked to species-specific characteristics, biological requirements, and environmental challenge.
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6
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Wang J, Yuan L, Tang J, Liu J, Sun C, Itgen MW, Chen G, Sessions SK, Zhang G, Mueller RL. Transposable element and host silencing activity in gigantic genomes. Front Cell Dev Biol 2023; 11:1124374. [PMID: 36910142 PMCID: PMC9998948 DOI: 10.3389/fcell.2023.1124374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/09/2023] [Indexed: 02/26/2023] Open
Abstract
Transposable elements (TEs) and the silencing machinery of their hosts are engaged in a germline arms-race dynamic that shapes TE accumulation and, therefore, genome size. In animal species with extremely large genomes (>10 Gb), TE accumulation has been pushed to the extreme, prompting the question of whether TE silencing also deviates from typical conditions. To address this question, we characterize TE silencing via two pathways-the piRNA pathway and KRAB-ZFP transcriptional repression-in the male and female gonads of Ranodon sibiricus, a salamander species with a ∼21 Gb genome. We quantify 1) genomic TE diversity, 2) TE expression, and 3) small RNA expression and find a significant relationship between the expression of piRNAs and TEs they target for silencing in both ovaries and testes. We also quantified TE silencing pathway gene expression in R. sibiricus and 14 other vertebrates with genome sizes ranging from 1 to 130 Gb and find no association between pathway expression and genome size. Taken together, our results reveal that the gigantic R. sibiricus genome includes at least 19 putatively active TE superfamilies, all of which are targeted by the piRNA pathway in proportion to their expression levels, suggesting comprehensive piRNA-mediated silencing. Testes have higher TE expression than ovaries, suggesting that they may contribute more to the species' high genomic TE load. We posit that apparently conflicting interpretations of TE silencing and genomic gigantism in the literature, as well as the absence of a correlation between TE silencing pathway gene expression and genome size, can be reconciled by considering whether the TE community or the host is currently "on the attack" in the arms race dynamic.
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Affiliation(s)
- Jie Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Liang Yuan
- School of Life Sciences, Xinjiang Normal University, Urumqi, China
| | - Jiaxing Tang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.,College of Life Sciences, Sichuan Normal University, Chengdu, China
| | - Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Cheng Sun
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Michael W Itgen
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | - Guiying Chen
- College of Life Sciences, Sichuan Normal University, Chengdu, China
| | | | - Guangpu Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.,College of Life Sciences, Sichuan Normal University, Chengdu, China
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7
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Shi Y, Chen B, Kong S, Zeng Q, Li L, Liu B, Pu F, Xu P. Comparative genomics analysis and genome assembly integration with the recombination landscape contribute to Takifugu bimaculatus assembly refinement. Gene 2022; 849:146910. [PMID: 36167181 DOI: 10.1016/j.gene.2022.146910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 09/13/2022] [Accepted: 09/19/2022] [Indexed: 11/28/2022]
Abstract
Takifugu genus has been brought to the fore in scientific and practical research due to its compact genome, explosive speciation progress and economic value. Here we updated the chromosome-level genome of Takifugu bimaculatus by an ultra-high-density linkage map, a classic and accurate way of chromosome assembly. The map constituted a robust assembly frame, with 92.2% (372.77 Mb) of the draft genome cumulatively placed. With intraspecies and interspecies comparative genomic analysis, we developed a criterion to quantify the differences between assemblies and established a novel way to integrate information from multiple assemblies. The integrated assembly rectified potential mis-assemblies, greatly improving the genome contiguity and correctness. Our results rendered profound information on the genetic recombination of T. bimaculatus and provided new insights into effective genome assembly. The consolidated assembly will be a contributory tool of T. bimaculatus and broadly across the Takifugu by providing a convincing reference for genomic research.
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Affiliation(s)
- Yue Shi
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Baohua Chen
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Shengnan Kong
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Qingmin Zeng
- Fisheries Research Institute of Fujian, Xiamen 361000, China
| | - Leibin Li
- Fisheries Research Institute of Fujian, Xiamen 361000, China
| | - Bo Liu
- Fisheries Research Institute of Fujian, Xiamen 361000, China
| | - Fei Pu
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Peng Xu
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Genetics and Breeding of Marine Organisms, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.
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8
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Jakt LM, Dubin A, Johansen SD. Intron size minimisation in teleosts. BMC Genomics 2022; 23:628. [PMID: 36050638 PMCID: PMC9438311 DOI: 10.1186/s12864-022-08760-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/13/2022] [Indexed: 11/17/2022] Open
Abstract
Background Spliceosomal introns are parts of primary transcripts that are removed by RNA splicing. Although introns apparently do not contribute to the function of the mature transcript, in vertebrates they comprise the majority of the transcribed region increasing the metabolic cost of transcription. The persistence of long introns across evolutionary time suggests functional roles that can offset this metabolic cost. The teleosts comprise one of the largest vertebrate clades. They have unusually compact and variable genome sizes and provide a suitable system for analysing intron evolution. Results We have analysed intron lengths in 172 vertebrate genomes and show that teleost intron lengths are relatively short, highly variable and bimodally distributed. Introns that were long in teleosts were also found to be long in mammals and were more likely to be found in regulatory genes and to contain conserved sequences. Our results argue that intron length has decreased in parallel in a non-random manner throughout teleost evolution and represent a deviation from the ancestral state. Conclusion Our observations indicate an accelerated rate of intron size evolution in the teleosts and that teleost introns can be divided into two classes by their length. Teleost intron sizes have evolved primarily as a side-effect of genome size evolution and small genomes are dominated by short introns (<256 base pairs). However, a non-random subset of introns has resisted this process across the teleosts and these are more likely have functional roles in all vertebrate clades. Supplementary Information The online version contains supplementary material available at (10.1186/s12864-022-08760-w).
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Affiliation(s)
- Lars Martin Jakt
- Faculty for bioscience and aquaculture, Nord University, Universitetsalléen 11, Bodoe, 8026, Norway.
| | - Arseny Dubin
- Faculty for bioscience and aquaculture, Nord University, Universitetsalléen 11, Bodoe, 8026, Norway.,Currently at: Parental Investment and Immune Dynamics, GEOMAR Helmholtz Centre for Ocean Research, Düsternbrookerweg 20, Kiel, D-24105, Germany
| | - Steinar Daae Johansen
- Faculty for bioscience and aquaculture, Nord University, Universitetsalléen 11, Bodoe, 8026, Norway
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9
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Brazier T, Glémin S. Diversity and determinants of recombination landscapes in flowering plants. PLoS Genet 2022; 18:e1010141. [PMID: 36040927 PMCID: PMC9467342 DOI: 10.1371/journal.pgen.1010141] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 09/12/2022] [Accepted: 08/05/2022] [Indexed: 11/19/2022] Open
Abstract
During meiosis, crossover rates are not randomly distributed along the chromosome and their location may have a strong impact on the functioning and evolution of the genome. To date, the broad diversity of recombination landscapes among plants has rarely been investigated and a formal comparative genomic approach is still needed to characterize and assess the determinants of recombination landscapes among species and chromosomes. We gathered genetic maps and genomes for 57 flowering plant species, corresponding to 665 chromosomes, for which we estimated large-scale recombination landscapes. We found that the number of crossover per chromosome spans a limited range (between one to five/six) whatever the genome size, and that there is no single relationship across species between genetic map length and chromosome size. Instead, we found a general relationship between the relative size of chromosomes and recombination rate, while the absolute length constrains the basal recombination rate for each species. At the chromosome level, we identified two main patterns (with a few exceptions) and we proposed a conceptual model explaining the broad-scale distribution of crossovers where both telomeres and centromeres play a role. These patterns correspond globally to the underlying gene distribution, which affects how efficiently genes are shuffled at meiosis. These results raised new questions not only on the evolution of recombination rates but also on their distribution along chromosomes.
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Affiliation(s)
- Thomas Brazier
- University of Rennes, CNRS, ECOBIO (Ecosystems, Biodiversity, Evolution), Rennes, France
| | - Sylvain Glémin
- University of Rennes, CNRS, ECOBIO (Ecosystems, Biodiversity, Evolution), Rennes, France
- Department of Ecology and Genetics, Evolutionary Biology Center and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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10
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Shaikhutdinov N, Gusev O. Chironomid midges (Diptera) provide insights into genome evolution in extreme environments. CURRENT OPINION IN INSECT SCIENCE 2022; 49:101-107. [PMID: 34990872 DOI: 10.1016/j.cois.2021.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/11/2021] [Accepted: 12/29/2021] [Indexed: 06/14/2023]
Abstract
Extremophiles often undergo marked changes in genomic architecture, likely as a result of adaptation to the harsh environments they inhabit. These changes can involve gene duplications that affect subsequent gene evolution and the regulation of gene expression. Excellent examples of this are provided by two non-biting chironomid midges (Diptera, Chironomidae): Polypedilum vanderplanki, which in its larval form can withstand almost complete water loss, and Belgica antarctica, which exhibits freeze tolerance. This review presents recent studies on the molecular adaptations and evolutionary features of these and other extremophile chironomid genomes, as well as biotechnological applications of a cell line derived from P. vanderplanki that can survive air-drying. We highlight the importance of genomics in identifying molecular pathways and genomic modifications associated with adaptation to extreme environmental conditions.
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Affiliation(s)
- Nurislam Shaikhutdinov
- Extreme Biology Laboratory, Regulatory Genomics Research Center, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, 420012, Russia; Center of Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205, Russia
| | - Oleg Gusev
- Extreme Biology Laboratory, Regulatory Genomics Research Center, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, 420012, Russia; Graduate School of Medicine, Juntendo University, Tokyo, 113-8421, Japan; RIKEN Center for Integrative Medical Sciences, RIKEN, Yokohama, 230-004, Japan.
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11
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Lehmann R, Kovařík A, Ocalewicz K, Kirtiklis L, Zuccolo A, Tegner JN, Wanzenböck J, Bernatchez L, Lamatsch DK, Symonová R. DNA Transposon Expansion is Associated with Genome Size Increase in Mudminnows. Genome Biol Evol 2021; 13:6380143. [PMID: 34599322 PMCID: PMC8557787 DOI: 10.1093/gbe/evab228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2021] [Indexed: 12/20/2022] Open
Abstract
Genome sizes of eukaryotic organisms vary substantially, with whole-genome duplications (WGD) and transposable element expansion acting as main drivers for rapid genome size increase. The two North American mudminnows, Umbra limi and Umbra pygmaea, feature genomes about twice the size of their sister lineage Esocidae (e.g., pikes and pickerels). However, it is unknown whether all Umbra species share this genome expansion and which causal mechanisms drive this expansion. Using flow cytometry, we find that the genome of the European mudminnow is expanded similarly to both North American species, ranging between 4.5 and 5.4 pg per diploid nucleus. Observed blocks of interstitially located telomeric repeats in U. limi suggest frequent Robertsonian rearrangements in its history. Comparative analyses of transcriptome and genome assemblies show that the genome expansion in Umbra is driven by the expansion of DNA transposon and unclassified repeat sequences without WGD. Furthermore, we find a substantial ongoing expansion of repeat sequences in the Alaska blackfish Dallia pectoralis, the closest relative to the family Umbridae, which might mark the beginning of a similar genome expansion. Our study suggests that the genome expansion in mudminnows, driven mainly by transposon expansion, but not WGD, occurred before the separation into the American and European lineage.
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Affiliation(s)
- Robert Lehmann
- Division of Biological and Environmental Sciences & Engineering, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Aleš Kovařík
- Laboratory of Molecular Epigenetics, Institute of Biophysics, Czech Academy of Science, Brno, Czech Republic
| | - Konrad Ocalewicz
- Department of Marine Biology and Ecology, Institute of Oceanography, Faculty of Oceanography and Geography, University of Gdansk, Gdansk, Poland
| | - Lech Kirtiklis
- Department of Zoology, Faculty of Biology and Biotechnology, University of Warmia and Mazury, Olsztyn, Poland
| | - Andrea Zuccolo
- Center for Desert Agriculture, Biological and Environmental Sciences & Engineering Division (BESE), King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Jesper N Tegner
- Division of Biological and Environmental Sciences & Engineering, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Josef Wanzenböck
- Research Department for Limnology Mondsee, University of Innsbruck, Mondsee, Austria
| | - Louis Bernatchez
- Department of Biology, IBIS (Institut de Biologie Intégrative et des Systèmes), Université Laval, Québec, QC, Canada
| | - Dunja K Lamatsch
- Research Department for Limnology Mondsee, University of Innsbruck, Mondsee, Austria
| | - Radka Symonová
- Department of Bioinformatics, Wissenschaftzentrum Weihenstephan, Technische Universität München, Freising, Germany.,Department of Biology, Faculty of Biology, University of Hradec Kralove, Czech Republic
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12
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Almojil D, Bourgeois Y, Falis M, Hariyani I, Wilcox J, Boissinot S. The Structural, Functional and Evolutionary Impact of Transposable Elements in Eukaryotes. Genes (Basel) 2021; 12:genes12060918. [PMID: 34203645 PMCID: PMC8232201 DOI: 10.3390/genes12060918] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/22/2022] Open
Abstract
Transposable elements (TEs) are nearly ubiquitous in eukaryotes. The increase in genomic data, as well as progress in genome annotation and molecular biology techniques, have revealed the vast number of ways mobile elements have impacted the evolution of eukaryotes. In addition to being the main cause of difference in haploid genome size, TEs have affected the overall organization of genomes by accumulating preferentially in some genomic regions, by causing structural rearrangements or by modifying the recombination rate. Although the vast majority of insertions is neutral or deleterious, TEs have been an important source of evolutionary novelties and have played a determinant role in the evolution of fundamental biological processes. TEs have been recruited in the regulation of host genes and are implicated in the evolution of regulatory networks. They have also served as a source of protein-coding sequences or even entire genes. The impact of TEs on eukaryotic evolution is only now being fully appreciated and the role they may play in a number of biological processes, such as speciation and adaptation, remains to be deciphered.
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Affiliation(s)
- Dareen Almojil
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates; (D.A.); (M.F.); (I.H.); (J.W.)
| | - Yann Bourgeois
- School of Biological Sciences, University of Portsmouth, Portsmouth, UK;
| | - Marcin Falis
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates; (D.A.); (M.F.); (I.H.); (J.W.)
| | - Imtiyaz Hariyani
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates; (D.A.); (M.F.); (I.H.); (J.W.)
| | - Justin Wilcox
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates; (D.A.); (M.F.); (I.H.); (J.W.)
- Center for Genomics and Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates
| | - Stéphane Boissinot
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates; (D.A.); (M.F.); (I.H.); (J.W.)
- Center for Genomics and Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi P.O. Box 129188, United Arab Emirates
- Correspondence:
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Lamichhaney S, Catullo R, Keogh JS, Clulow S, Edwards SV, Ezaz T. A bird-like genome from a frog: Mechanisms of genome size reduction in the ornate burrowing frog, Platyplectrum ornatum. Proc Natl Acad Sci U S A 2021; 118:e2011649118. [PMID: 33836564 PMCID: PMC7980411 DOI: 10.1073/pnas.2011649118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The diversity of genome sizes across the tree of life is of key interest in evolutionary biology. Various correlates of variation in genome size, such as accumulation of transposable elements (TEs) or rate of DNA gain and loss, are well known, but the underlying molecular mechanisms driving or constraining genome size are poorly understood. Here, we study one of the smallest genomes among frogs characterized thus far, that of the ornate burrowing frog (Platyplectrum ornatum) from Australia, and compare it to other published frog and vertebrate genomes to examine the forces driving reduction in genome size. At ∼1.06 gigabases (Gb), the P. ornatum genome is like that of birds, revealing four major mechanisms underlying TE dynamics: reduced abundance of all major classes of TEs; increased net deletion bias in TEs; drastic reduction in intron lengths; and expansion via gene duplication of the repertoire of TE-suppressing Piwi genes, accompanied by increased expression of Piwi-interacting RNA (piRNA)-based TE-silencing pathway genes in germline cells. Transcriptomes from multiple tissues in both sexes corroborate these results and provide insight into sex-differentiation pathways in Platyplectrum Genome skimming of two closely related frog species (Lechriodus fletcheri and Limnodynastes fletcheri) confirms a reduction in TEs as a major driver of genome reduction in Platyplectrum and supports a macroevolutionary scenario of small genome size in frogs driven by convergence in life history, especially rapid tadpole development and tadpole diet. The P. ornatum genome offers a model for future comparative studies on mechanisms of genome size reduction in amphibians and vertebrates generally.
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Affiliation(s)
- Sangeet Lamichhaney
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Renee Catullo
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Acton, ACT, Australia 2601
- Australian National Insect Collection and Future Science Platform Environomics, Commonwealth Scientific and Industrial Research Organization, Acton, ACT, Australia 2601
| | - J Scott Keogh
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Acton, ACT, Australia 2601
| | - Simon Clulow
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia 2109
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138;
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138
| | - Tariq Ezaz
- Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, ACT, Australia 2617
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Borůvková V, Howell WM, Matoulek D, Symonová R. Quantitative Approach to Fish Cytogenetics in the Context of Vertebrate Genome Evolution. Genes (Basel) 2021; 12:genes12020312. [PMID: 33671814 PMCID: PMC7926999 DOI: 10.3390/genes12020312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/01/2021] [Accepted: 02/17/2021] [Indexed: 01/14/2023] Open
Abstract
Our novel Python-based tool EVANGELIST allows the visualization of GC and repeats percentages along chromosomes in sequenced genomes and has enabled us to perform quantitative large-scale analyses on the chromosome level in fish and other vertebrates. This is a different approach from the prevailing analyses, i.e., analyses of GC% in the coding sequences that make up not more than 2% in human. We identified GC content (GC%) elevations in microchromosomes in ancient fish lineages similar to avian microchromosomes and a large variability in the relationship between the chromosome size and their GC% across fish lineages. This raises the question as to what extent does the chromosome size drive GC% as posited by the currently accepted explanation based on the recombination rate. We ascribe the differences found across fishes to varying GC% of repetitive sequences. Generally, our results suggest that the GC% of repeats and proportion of repeats are independent of the chromosome size. This leaves an open space for another mechanism driving the GC evolution in vertebrates.
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Affiliation(s)
- Veronika Borůvková
- Faculty of Science, University of Hradec Kralove, 500 03 Hradec Kralove, Czech Republic; (V.B.); (D.M.)
| | - W. Mike Howell
- Department of Biological and Environmental Sciences, Samford University, Birmingham, AL 35226, USA;
| | - Dominik Matoulek
- Faculty of Science, University of Hradec Kralove, 500 03 Hradec Kralove, Czech Republic; (V.B.); (D.M.)
| | - Radka Symonová
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, 85354 Freising, Germany
- Correspondence:
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15
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Bourgeois Y, Ruggiero RP, Hariyani I, Boissinot S. Disentangling the determinants of transposable elements dynamics in vertebrate genomes using empirical evidences and simulations. PLoS Genet 2020; 16:e1009082. [PMID: 33017388 PMCID: PMC7561263 DOI: 10.1371/journal.pgen.1009082] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/15/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022] Open
Abstract
The interactions between transposable elements (TEs) and their hosts constitute one of the most profound co-evolutionary processes found in nature. The population dynamics of TEs depends on factors specific to each TE families, such as the rate of transposition and insertional preference, the demographic history of the host and the genomic landscape. How these factors interact has yet to be investigated holistically. Here we are addressing this question in the green anole (Anolis carolinensis) whose genome contains an extraordinary diversity of TEs (including non-LTR retrotransposons, SINEs, LTR-retrotransposons and DNA transposons). We observed a positive correlation between recombination rate and frequency of TEs and densities for LINEs, SINEs and DNA transposons. For these elements, there was a clear impact of demography on TE frequency and abundance, with a loss of polymorphic elements and skewed frequency spectra in recently expanded populations. On the other hand, some LTR-retrotransposons displayed patterns consistent with a very recent phase of intense amplification. To determine how demography, genomic features and intrinsic properties of TEs interact we ran simulations using SLiM3. We determined that i) short TE insertions are not strongly counter-selected, but long ones are, ii) neutral demographic processes, linked selection and preferential insertion may explain positive correlations between average TE frequency and recombination, iii) TE insertions are unlikely to have been massively recruited in recent adaptation. We demonstrate that deterministic and stochastic processes have different effects on categories of TEs and that a combination of empirical analyses and simulations can disentangle these mechanisms.
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Affiliation(s)
- Yann Bourgeois
- School of Biological Sciences, University of Portsmouth, Portsmouth, United Kingdom
- New York University Abu Dhabi, Saadiyat Island Campus, Abu Dhabi, United Arab Emirates
- * E-mail: (YB); (SB)
| | - Robert P. Ruggiero
- New York University Abu Dhabi, Saadiyat Island Campus, Abu Dhabi, United Arab Emirates
- Department of Biology, Southeast Missouri State University, Cape Girardeau, MO, United States of America
| | - Imtiyaz Hariyani
- New York University Abu Dhabi, Saadiyat Island Campus, Abu Dhabi, United Arab Emirates
| | - Stéphane Boissinot
- New York University Abu Dhabi, Saadiyat Island Campus, Abu Dhabi, United Arab Emirates
- * E-mail: (YB); (SB)
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16
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Blommaert J. Genome size evolution: towards new model systems for old questions. Proc Biol Sci 2020; 287:20201441. [PMID: 32842932 PMCID: PMC7482279 DOI: 10.1098/rspb.2020.1441] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022] Open
Abstract
Genome size (GS) variation is a fundamental biological characteristic; however, its evolutionary causes and consequences are the topic of ongoing debate. Whether GS is a neutral trait or one subject to selective pressures, and how strong these selective pressures are, may remain open questions. Fundamentally, the genomic sequences responsible for this variation directly impact the potential evolutionary outcomes and, equally, are the targets of different evolutionary pressures. For example, duplications and deletions of genic regions (large or small) can have immediate and drastic phenotypic effects, while an expansion or contraction of non-coding DNA is less likely to cause catastrophic phenotypic effects. However, in the long term, the accumulation or deletion of ncDNA is likely to have larger effects. Modern sequencing technologies are allowing for the dissection of these proximate causes, but a combination of these new technologies with more traditional evolutionary experiments and approaches could revolutionize this debate and potentially resolve many of these arguments. Here, I discuss an ambitious way forward for GS research, putting it in context of historical debates, theories and sometimes contradictory evidence, and highlighting the promise of combining new sequencing technologies and analytical developments with more traditional experimental evolution approaches.
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Affiliation(s)
- Julie Blommaert
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
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17
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Barton HJ, Zeng K. The Impact of Natural Selection on Short Insertion and Deletion Variation in the Great Tit Genome. Genome Biol Evol 2019; 11:1514-1524. [PMID: 30924871 PMCID: PMC6543879 DOI: 10.1093/gbe/evz068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2019] [Indexed: 12/11/2022] Open
Abstract
Insertions and deletions (INDELs) remain understudied, despite being the most common form of genetic variation after single nucleotide polymorphisms. This stems partly from the challenge of correctly identifying the ancestral state of an INDEL and thus identifying it as an insertion or a deletion. Erroneously assigned ancestral states can skew the site frequency spectrum, leading to artificial signals of selection. Consequently, the selective pressures acting on INDELs are, at present, poorly resolved. To tackle this issue, we have recently published a maximum likelihood approach to estimate the mutation rate and the distribution of fitness effects for INDELs. Our approach estimates and controls for the rate of ancestral state misidentification, overcoming issues plaguing previous INDEL studies. Here, we apply the method to INDEL polymorphism data from ten high coverage (∼44×) European great tit (Parus major) genomes. We demonstrate that coding INDELs are under strong purifying selection with a small proportion making it into the population (∼4%). However, among fixed coding INDELs, 71% of insertions and 86% of deletions are fixed by positive selection. In noncoding regions, we estimate ∼80% of insertions and ∼52% of deletions are effectively neutral, the remainder show signatures of purifying selection. Additionally, we see evidence of linked selection reducing INDEL diversity below background levels, both in proximity to exons and in areas of low recombination.
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Affiliation(s)
- Henry J Barton
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
| | - Kai Zeng
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
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18
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Lertzman-Lepofsky G, Mooers AØ, Greenberg DA. Ecological constraints associated with genome size across salamander lineages. Proc Biol Sci 2019; 286:20191780. [PMID: 31530144 DOI: 10.1098/rspb.2019.1780] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Salamanders have some of the largest, and most variable, genome sizes among the vertebrates. Larger genomes have been associated with larger cell sizes, lower metabolic rates, and longer embryonic and larval durations in many different taxonomic groups. These life-history traits are often important for dictating fitness under different environmental conditions, suggesting that a species' genome size may have the potential to constrain its ecological distribution. We test how genome size varies with the ephemerality of larval habitat across the salamanders, predicting that species with larger genomes will be constrained to more permanent habitats that permit slower development, while species with smaller genomes will be more broadly distributed across the gradient of habitat ephemerality. We found that salamanders with larger genomes are almost exclusively associated with permanent aquatic habitats. In addition, the evolutionary transition rate between permanent and ephemeral larval habitats is much higher in salamander lineages with smaller genome sizes. These patterns suggest that genome size may act as an evolutionary constraint on the ecological habitats of salamanders, restricting those species with large genomes and slower development to habitats with permanent sources of water.
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Affiliation(s)
- Gavia Lertzman-Lepofsky
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Arne Ø Mooers
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - Dan A Greenberg
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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19
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Bourgeois Y, Boissinot S. On the Population Dynamics of Junk: A Review on the Population Genomics of Transposable Elements. Genes (Basel) 2019; 10:genes10060419. [PMID: 31151307 PMCID: PMC6627506 DOI: 10.3390/genes10060419] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/05/2019] [Accepted: 05/21/2019] [Indexed: 01/18/2023] Open
Abstract
Transposable elements (TEs) play an important role in shaping genomic organization and structure, and may cause dramatic changes in phenotypes. Despite the genetic load they may impose on their host and their importance in microevolutionary processes such as adaptation and speciation, the number of population genetics studies focused on TEs has been rather limited so far compared to single nucleotide polymorphisms (SNPs). Here, we review the current knowledge about the dynamics of transposable elements at recent evolutionary time scales, and discuss the mechanisms that condition their abundance and frequency. We first discuss non-adaptive mechanisms such as purifying selection and the variable rates of transposition and elimination, and then focus on positive and balancing selection, to finally conclude on the potential role of TEs in causing genomic incompatibilities and eventually speciation. We also suggest possible ways to better model TEs dynamics in a population genomics context by incorporating recent advances in TEs into the rich information provided by SNPs about the demography, selection, and intrinsic properties of genomes.
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Affiliation(s)
- Yann Bourgeois
- New York University Abu Dhabi, P.O. 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates.
| | - Stéphane Boissinot
- New York University Abu Dhabi, P.O. 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates.
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20
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Manthey JD, Moyle RG, Boissinot S. Multiple and Independent Phases of Transposable Element Amplification in the Genomes of Piciformes (Woodpeckers and Allies). Genome Biol Evol 2018; 10:1445-1456. [PMID: 29850797 PMCID: PMC6007501 DOI: 10.1093/gbe/evy105] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2018] [Indexed: 12/15/2022] Open
Abstract
The small and conserved genomes of birds are likely a result of flight-related metabolic constraints. Recombination-driven deletions and minimal transposable element (TE) expansions have led to continually shrinking genomes during evolution of many lineages of volant birds. Despite constraints of genome size in birds, we identified multiple waves of amplification of TEs in Piciformes (woodpeckers, honeyguides, toucans, and barbets). Relative to other bird species’ genomic TE abundance (< 10% of genome), we found ∼17–30% TE content in multiple clades within Piciformes. Several families of the retrotransposon superfamily chicken repeat 1 (CR1) expanded in at least three different waves of activity. The most recent CR1 expansions (∼4–7% of genome) preceded bursts of diversification in the woodpecker clade and in the American barbets + toucans clade. Additionally, we identified several thousand polymorphic CR1 insertions (hundreds per individual) in three closely related woodpecker species. Woodpecker CR1 insertion polymorphisms are maintained at lower frequencies than single nucleotide polymorphisms indicating that purifying selection is acting against additional CR1 copies and that these elements impose a fitness cost on their host. These findings provide evidence of large scale and ongoing TE activity in avian genomes despite continual constraint on genome size.
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Affiliation(s)
- Joseph D Manthey
- New York University Abu Dhabi, UAE.,Department of Biological Sciences, Texas Tech University
| | - Robert G Moyle
- Department of Ecology and Evolutionary Biology, Biodiversity Institute, University of Kansas
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21
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Roesti M. Varied Genomic Responses to Maladaptive Gene Flow and Their Evidence. Genes (Basel) 2018; 9:E298. [PMID: 29899287 PMCID: PMC6027369 DOI: 10.3390/genes9060298] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/17/2018] [Accepted: 05/30/2018] [Indexed: 12/02/2022] Open
Abstract
Adaptation to a local environment often occurs in the face of maladaptive gene flow. In this perspective, I discuss several ideas on how a genome may respond to maladaptive gene flow during adaptation. On the one hand, selection can build clusters of locally adaptive alleles at fortuitously co-localized loci within a genome, thereby facilitating local adaptation with gene flow ('allele-only clustering'). On the other hand, the selective pressure to link adaptive alleles may drive co-localization of the actual loci relevant for local adaptation within a genome through structural genome changes or an evolving intra-genomic crossover rate ('locus clustering'). While the expected outcome is, in both cases, a higher frequency of locally adaptive alleles in some genome regions than others, the molecular units evolving in response to gene flow differ (i.e., alleles versus loci). I argue that, although making this distinction is important, we commonly lack the critical empirical evidence to do so. This is mainly because many current approaches are biased towards detecting local adaptation in genome regions with low crossover rates. The importance of low-crossover genome regions for adaptation with gene flow, such as in co-localizing relevant loci within a genome, thus remains unclear. Future empirical investigations should address these questions by making use of comparative genomics, where multiple de novo genome assemblies from species evolved under different degrees of genetic exchange are compared. This research promises to advance our understanding of how a genome adapts to maladaptive gene flow, thereby promoting adaptive divergence and reproductive isolation.
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Affiliation(s)
- Marius Roesti
- Biodiversity Research Centre and Zoology Department, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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22
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Stapley J, Feulner PGD, Johnston SE, Santure AW, Smadja CM. Variation in recombination frequency and distribution across eukaryotes: patterns and processes. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0455. [PMID: 29109219 PMCID: PMC5698618 DOI: 10.1098/rstb.2016.0455] [Citation(s) in RCA: 212] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2017] [Indexed: 01/04/2023] Open
Abstract
Recombination, the exchange of DNA between maternal and paternal chromosomes during meiosis, is an essential feature of sexual reproduction in nearly all multicellular organisms. While the role of recombination in the evolution of sex has received theoretical and empirical attention, less is known about how recombination rate itself evolves and what influence this has on evolutionary processes within sexually reproducing organisms. Here, we explore the patterns of, and processes governing recombination in eukaryotes. We summarize patterns of variation, integrating current knowledge with an analysis of linkage map data in 353 organisms. We then discuss proximate and ultimate processes governing recombination rate variation and consider how these influence evolutionary processes. Genome-wide recombination rates (cM/Mb) can vary more than tenfold across eukaryotes, and there is large variation in the distribution of recombination events across closely related taxa, populations and individuals. We discuss how variation in rate and distribution relates to genome architecture, genetic and epigenetic mechanisms, sex, environmental perturbations and variable selective pressures. There has been great progress in determining the molecular mechanisms governing recombination, and with the continued development of new modelling and empirical approaches, there is now also great opportunity to further our understanding of how and why recombination rate varies.This article is part of the themed issue 'Evolutionary causes and consequences of recombination rate variation in sexual organisms'.
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Affiliation(s)
- Jessica Stapley
- Centre for Adaptation to a Changing Environment, IBZ, ETH Zürich, 8092 Zürich, Switzerland
| | - Philine G D Feulner
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland.,Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JY, UK
| | - Anna W Santure
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Carole M Smadja
- Institut des Sciences de l'Evolution UMR 5554, CNRS, IRD, EPHE, Université de Montpellier, 3095 Montpellier cedex 05, France
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23
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Haenel Q, Laurentino TG, Roesti M, Berner D. Meta-analysis of chromosome-scale crossover rate variation in eukaryotes and its significance to evolutionary genomics. Mol Ecol 2018; 27:2477-2497. [PMID: 29676042 DOI: 10.1111/mec.14699] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 01/02/2023]
Abstract
Understanding the distribution of crossovers along chromosomes is crucial to evolutionary genomics because the crossover rate determines how strongly a genome region is influenced by natural selection on linked sites. Nevertheless, generalities in the chromosome-scale distribution of crossovers have not been investigated formally. We fill this gap by synthesizing joint information on genetic and physical maps across 62 animal, plant and fungal species. Our quantitative analysis reveals a strong and taxonomically widespread reduction of the crossover rate in the centre of chromosomes relative to their peripheries. We demonstrate that this pattern is poorly explained by the position of the centromere, but find that the magnitude of the relative reduction in the crossover rate in chromosome centres increases with chromosome length. That is, long chromosomes often display a dramatically low crossover rate in their centre, whereas short chromosomes exhibit a relatively homogeneous crossover rate. This observation is compatible with a model in which crossover is initiated from the chromosome tips, an idea with preliminary support from mechanistic investigations of meiotic recombination. Consequently, we show that organisms achieve a higher genome-wide crossover rate by evolving smaller chromosomes. Summarizing theory and providing empirical examples, we finally highlight that taxonomically widespread and systematic heterogeneity in crossover rate along chromosomes generates predictable broad-scale trends in genetic diversity and population differentiation by modifying the impact of natural selection among regions within a genome. We conclude by emphasizing that chromosome-scale heterogeneity in crossover rate should urgently be incorporated into analytical tools in evolutionary genomics, and in the interpretation of resulting patterns.
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Affiliation(s)
- Quiterie Haenel
- Zoological Institute, University of Basel, Basel, Switzerland
| | | | - Marius Roesti
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Daniel Berner
- Zoological Institute, University of Basel, Basel, Switzerland
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24
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Buckley RM, Kortschak RD, Adelson DL. Divergent genome evolution caused by regional variation in DNA gain and loss between human and mouse. PLoS Comput Biol 2018; 14:e1006091. [PMID: 29677183 PMCID: PMC5931693 DOI: 10.1371/journal.pcbi.1006091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 05/02/2018] [Accepted: 03/15/2018] [Indexed: 12/31/2022] Open
Abstract
The forces driving the accumulation and removal of non-coding DNA and ultimately the evolution of genome size in complex organisms are intimately linked to genome structure and organisation. Our analysis provides a novel method for capturing the regional variation of lineage-specific DNA gain and loss events in their respective genomic contexts. To further understand this connection we used comparative genomics to identify genome-wide individual DNA gain and loss events in the human and mouse genomes. Focusing on the distribution of DNA gains and losses, relationships to important structural features and potential impact on biological processes, we found that in autosomes, DNA gains and losses both followed separate lineage-specific accumulation patterns. However, in both species chromosome X was particularly enriched for DNA gain, consistent with its high L1 retrotransposon content required for X inactivation. We found that DNA loss was associated with gene-rich open chromatin regions and DNA gain events with gene-poor closed chromatin regions. Additionally, we found that DNA loss events tended to be smaller than DNA gain events suggesting that they were able to accumulate in gene-rich open chromatin regions due to their reduced capacity to interrupt gene regulatory architecture. GO term enrichment showed that mouse loss hotspots were strongly enriched for terms related to developmental processes. However, these genes were also located in regions with a high density of conserved elements, suggesting that despite high levels of DNA loss, gene regulatory architecture remained conserved. This is consistent with a model in which DNA gain and loss results in turnover or "churning" in regulatory element dense regions of open chromatin, where interruption of regulatory elements is selected against.
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Affiliation(s)
- Reuben M. Buckley
- Department of Genetics and Evolution, The University of Adelaide, North Tce, Adelaide, Australia
| | - R. Daniel Kortschak
- Department of Genetics and Evolution, The University of Adelaide, North Tce, Adelaide, Australia
| | - David L. Adelson
- Department of Genetics and Evolution, The University of Adelaide, North Tce, Adelaide, Australia
- * E-mail:
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25
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Sookdeo A, Hepp CM, Boissinot S. Contrasted patterns of evolution of the LINE-1 retrotransposon in perissodactyls: the history of a LINE-1 extinction. Mob DNA 2018; 9:12. [PMID: 29610583 PMCID: PMC5872511 DOI: 10.1186/s13100-018-0117-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/22/2018] [Indexed: 12/30/2022] Open
Abstract
Background LINE-1 (L1) is the dominant autonomously replicating non-LTR retrotransposon in mammals. Although our knowledge of L1 evolution across the tree of life has considerably improved in recent years, what we know of L1 evolution in mammals is biased and comes mostly from studies in primates (mostly human) and rodents (mostly mouse). It is unclear if patterns of evolution that are shared between those two groups apply to other mammalian orders. Here we performed a detailed study on the evolution of L1 in perissodactyls by making use of the complete genome of the domestic horse and of the white rhinoceros. This mammalian order offers an excellent model to study the extinction of L1 since the rhinoceros is one of the few mammalian species to have lost active L1. Results We found that multiple L1 lineages, carrying different 5’UTRs, have been simultaneously active during the evolution of perissodactyls. We also found that L1 has continuously amplified and diversified in horse. In rhinoceros, L1 was very prolific early on. Two successful families were simultaneously active until ~20my ago but became extinct suddenly at exactly the same time. Conclusions The general pattern of L1 evolution in perissodactyls is very similar to what was previously described in mouse and human, suggesting some commonalities in the way mammalian genomes interact with L1. We confirmed the extinction of L1 in rhinoceros and we discuss several possible mechanisms. Electronic supplementary material The online version of this article (10.1186/s13100-018-0117-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Akash Sookdeo
- 1Department of Biology, New York University, New York, NY USA
| | - Crystal M Hepp
- 2School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ USA
| | - Stéphane Boissinot
- 3New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
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Zhai Y, Alexandre BC. A Poissonian Model of Indel Rate Variation for Phylogenetic Tree Inference. Syst Biol 2018; 66:698-714. [PMID: 28204784 DOI: 10.1093/sysbio/syx033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 01/27/2017] [Indexed: 01/22/2023] Open
Abstract
While indel rate variation has been observed and analyzed in detail, it is not taken into account by current indel-aware phylogenetic reconstruction methods. In this work, we introduce a continuous time stochastic process, the geometric Poisson indel process, that generalizes the Poisson indel process by allowing insertion and deletion rates to vary across sites. We design an efficient algorithm for computing the probability of a given multiple sequence alignment based on our new indel model. We describe a method to construct phylogeny estimates from a fixed alignment using neighbor joining. Using simulation studies, we show that ignoring indel rate variation may have a detrimental effect on the accuracy of the inferred phylogenies, and that our proposed method can sidestep this issue by inferring latent indel rate categories. We also show that our phylogenetic inference method may be more stable to taxa subsampling than methods that either ignore indels or indel rate variation. [evolutionary stochastic process; indel rate variation; Poisson indel process; TKF91.].
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Affiliation(s)
- Yongliang Zhai
- Department of Statistics, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Bouchard-Côté Alexandre
- Department of Statistics, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
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27
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Burri R. Interpreting differentiation landscapes in the light of long-term linked selection. Evol Lett 2017. [DOI: 10.1002/evl3.14] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Reto Burri
- Department of Population Ecology; Friedrich Schiller University Jena; Dornburger Strasse 159 D-07743 Jena Germany
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28
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Du YP, Bi Y, Zhang MF, Yang FP, Jia GX, Zhang XH. Genome Size Diversity in Lilium (Liliaceae) Is Correlated with Karyotype and Environmental Traits. FRONTIERS IN PLANT SCIENCE 2017; 8:1303. [PMID: 28798759 PMCID: PMC5526928 DOI: 10.3389/fpls.2017.01303] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/11/2017] [Indexed: 05/25/2023]
Abstract
Genome size (GS) diversity is of fundamental biological importance. The occurrence of giant genomes in angiosperms is restricted to just a few lineages in the analyzed genome size of plant species so far. It is still an open question whether GS diversity is shaped by neutral or natural selection. The genus Lilium, with giant genomes, is phylogenetically and horticulturally important and is distributed throughout the northern hemisphere. GS diversity in Lilium and the underlying evolutionary mechanisms are poorly understood. We performed a comprehensive study involving phylogenetically independent analysis on 71 species to explore the diversity and evolution of GS and its correlation with karyological and environmental traits within Lilium (including Nomocharis). The strong phylogenetic signal detected for GS in the genus provides evidence consistent with that the repetitive DNA may be the primary contributors to the GS diversity, while the significant positive relationships detected between GS and the haploid chromosome length (HCL) provide insights into patterns of genome evolution. The relationships between GS and karyotypes indicate that ancestral karyotypes of Lilium are likely to have exhibited small genomes, low diversity in centromeric index (CVCI) values and relatively high relative variation in chromosome length (CVCL) values. Significant relationships identified between GS and annual temperature and between GS and annual precipitation suggest that adaptation to habitat strongly influences GS diversity. We conclude that GS in Lilium is shaped by both neutral (genetic drift) and adaptive evolution. These findings will have important consequences for understanding the evolution of giant plant genomes, and exploring the role of repetitive DNA fraction and chromosome changes in a plant group with large genomes and conservation of chromosome number.
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Affiliation(s)
- Yun-peng Du
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry SciencesBeijing, China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Engineering Technology Research Center of Functional FloricultureBeijing, China
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry UniversityBeijing, China
| | - Yu Bi
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry SciencesBeijing, China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Engineering Technology Research Center of Functional FloricultureBeijing, China
| | - Ming-fang Zhang
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry SciencesBeijing, China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Engineering Technology Research Center of Functional FloricultureBeijing, China
| | - Feng-ping Yang
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry SciencesBeijing, China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Engineering Technology Research Center of Functional FloricultureBeijing, China
| | - Gui-xia Jia
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture and College of Landscape Architecture, Beijing Forestry UniversityBeijing, China
| | - Xiu-hai Zhang
- Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry SciencesBeijing, China
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Engineering Technology Research Center of Functional FloricultureBeijing, China
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29
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Abstract
Genome size in mammals and birds shows remarkably little interspecific variation compared with other taxa. However, genome sequencing has revealed that many mammal and bird lineages have experienced differential rates of transposable element (TE) accumulation, which would be predicted to cause substantial variation in genome size between species. Thus, we hypothesize that there has been covariation between the amount of DNA gained by transposition and lost by deletion during mammal and avian evolution, resulting in genome size equilibrium. To test this model, we develop computational methods to quantify the amount of DNA gained by TE expansion and lost by deletion over the last 100 My in the lineages of 10 species of eutherian mammals and 24 species of birds. The results reveal extensive variation in the amount of DNA gained via lineage-specific transposition, but that DNA loss counteracted this expansion to various extents across lineages. Our analysis of the rate and size spectrum of deletion events implies that DNA removal in both mammals and birds has proceeded mostly through large segmental deletions (>10 kb). These findings support a unified "accordion" model of genome size evolution in eukaryotes whereby DNA loss counteracting TE expansion is a major determinant of genome size. Furthermore, we propose that extensive DNA loss, and not necessarily a dearth of TE activity, has been the primary force maintaining the greater genomic compaction of flying birds and bats relative to their flightless relatives.
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30
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Gion JM, Hudson CJ, Lesur I, Vaillancourt RE, Potts BM, Freeman JS. Genome-wide variation in recombination rate in Eucalyptus. BMC Genomics 2016; 17:590. [PMID: 27507140 PMCID: PMC4979139 DOI: 10.1186/s12864-016-2884-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Accepted: 07/06/2016] [Indexed: 11/25/2022] Open
Abstract
Background Meiotic recombination is a fundamental evolutionary process. It not only generates diversity, but influences the efficacy of natural selection and genome evolution. There can be significant heterogeneity in recombination rates within and between species, however this variation is not well understood outside of a few model taxa, particularly in forest trees. Eucalypts are forest trees of global economic importance, and dominate many Australian ecosystems. We studied recombination rate in Eucalyptus globulus using genetic linkage maps constructed in 10 unrelated individuals, and markers anchored to the Eucalyptus reference genome. This experimental design provided the replication to study whether recombination rate varied between individuals and chromosomes, and allowed us to study the genomic attributes and population genetic parameters correlated with this variation. Results Recombination rate varied significantly between individuals (range = 2.71 to 3.51 centimorgans/megabase [cM/Mb]), but was not significantly influenced by sex or cross type (F1 vs. F2). Significant differences in recombination rate between chromosomes were also evident (range = 1.98 to 3.81 cM/Mb), beyond those which were due to variation in chromosome size. Variation in chromosomal recombination rate was significantly correlated with gene density (r = 0.94), GC content (r = 0.90), and the number of tandem duplicated genes (r = −0.72) per chromosome. Notably, chromosome level recombination rate was also negatively correlated with the average genetic diversity across six species from an independent set of samples (r = −0.75). Conclusions The correlations with genomic attributes are consistent with findings in other taxa, however, the direction of the correlation between diversity and recombination rate is opposite to that commonly observed. We argue this is likely to reflect the interaction of selection and specific genome architecture of Eucalyptus. Interestingly, the differences amongst chromosomes in recombination rates appear stable across Eucalyptus species. Together with the strong correlations between recombination rate and features of the Eucalyptus reference genome, we maintain these findings provide further evidence for a broad conservation of genome architecture across the globally significant lineages of Eucalyptus.
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Affiliation(s)
| | - Corey J Hudson
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia.,Present address: Tasmanian Alkaloids, P.O. Box 130, Westbury, TAS, 7303, Australia
| | | | - René E Vaillancourt
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
| | - Brad M Potts
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
| | - Jules S Freeman
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia.
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31
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Ji Y, DeWoody JA. Genomic Landscape of Long Terminal Repeat Retrotransposons (LTR-RTs) and Solo LTRs as Shaped by Ectopic Recombination in Chicken and Zebra Finch. J Mol Evol 2016; 82:251-63. [PMID: 27154235 DOI: 10.1007/s00239-016-9741-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 04/26/2016] [Indexed: 11/25/2022]
Abstract
Transposable elements (TEs) are nearly ubiquitous among eukaryotic genomes, but TE contents vary dramatically among phylogenetic lineages. Several mechanisms have been proposed as drivers of TE dynamics in genomes, including the fixation/loss of a particular TE insertion by selection or drift as well as structural changes in the genome due to mutation (e.g., recombination). In particular, recombination can have a significant and directional effect on the genomic TE landscape. For example, ectopic recombination removes internal regions of long terminal repeat retrotransposons (LTR-RTs) as well as one long terminal repeat (LTR), resulting in a solo LTR. In this study, we focus on the intra-species dynamics of LTR-RTs and solo LTRs in bird genomes. The distribution of LTR-RTs and solo LTRs in birds is intriguing because avian recombination rates vary widely within a given genome. We used published linkage maps and whole genome assemblies to study the relationship between recombination rates and LTR-removal events in the chicken and zebra finch. We hypothesized that regions with low recombination rates would harbor more full-length LTR-RTs (and fewer solo LTRs) than regions with high recombination rates. We tested this hypothesis by comparing the ratio of full-length LTR-RTs and solo LTRs across chromosomes, across non-overlapping megabase windows, and across physical features (i.e., centromeres and telomeres). The chicken data statistically supported the hypothesis that recombination rates are inversely correlated with the ratio of full-length to solo LTRs at both the chromosome level and in 1-Mb non-overlapping windows. We also found that the ratio of full-length to solo LTRs near chicken telomeres was significantly lower than those ratios near centromeres. Our results suggest a potential role of ectopic recombination in shaping the chicken LTR-RT genomic landscape.
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Affiliation(s)
- Yanzhu Ji
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA.
| | - J Andrew DeWoody
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA.,Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
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32
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Recombination hotspots: Models and tools for detection. DNA Repair (Amst) 2016; 40:47-56. [PMID: 26991854 DOI: 10.1016/j.dnarep.2016.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 02/09/2016] [Indexed: 11/22/2022]
Abstract
Recombination hotspots are the regions within the genome where the rate, and the frequency of recombination are optimum with a size varying from 1 to 2kb. The recombination event is mediated by the double-stranded break formation, guided by the combined enzymatic action of DNA topoisomerase and Spo 11 endonuclease. These regions are distributed non-uniformly throughout the human genome and cause distortions in the genetic map. Numerous lines of evidence suggest that the number of hotspots known in humans has increased manifold in recent years. A few facts about the hotspot evolutions were also put forward, indicating the differences in the hotspot position between chimpanzees and humans. In mice, recombination hot spots were found to be clustered within the major histocompatibility complex (MHC) region. Several models, that help explain meiotic recombination has been proposed. Moreover, scientists also developed some computational tools to locate the hotspot position and estimate their recombination rate in humans is of great interest to population and medical geneticists. Here we reviewed the molecular mechanisms, models and in silico prediction techniques of hot spot residues.
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33
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Davey JW, Chouteau M, Barker SL, Maroja L, Baxter SW, Simpson F, Merrill RM, Joron M, Mallet J, Dasmahapatra KK, Jiggins CD. Major Improvements to the Heliconius melpomene Genome Assembly Used to Confirm 10 Chromosome Fusion Events in 6 Million Years of Butterfly Evolution. G3 (BETHESDA, MD.) 2016; 6:695-708. [PMID: 26772750 PMCID: PMC4777131 DOI: 10.1534/g3.115.023655] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/06/2016] [Indexed: 12/30/2022]
Abstract
The Heliconius butterflies are a widely studied adaptive radiation of 46 species spread across Central and South America, several of which are known to hybridize in the wild. Here, we present a substantially improved assembly of the Heliconius melpomene genome, developed using novel methods that should be applicable to improving other genome assemblies produced using short read sequencing. First, we whole-genome-sequenced a pedigree to produce a linkage map incorporating 99% of the genome. Second, we incorporated haplotype scaffolds extensively to produce a more complete haploid version of the draft genome. Third, we incorporated ∼20x coverage of Pacific Biosciences sequencing, and scaffolded the haploid genome using an assembly of this long-read sequence. These improvements result in a genome of 795 scaffolds, 275 Mb in length, with an N50 length of 2.1 Mb, an N50 number of 34, and with 99% of the genome placed, and 84% anchored on chromosomes. We use the new genome assembly to confirm that the Heliconius genome underwent 10 chromosome fusions since the split with its sister genus Eueides, over a period of about 6 million yr.
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Affiliation(s)
- John W Davey
- Department of Zoology, University of Cambridge, CB2 3EJ, United Kingdom
| | - Mathieu Chouteau
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS - EPHE - Université de Montpellier - Université Paul Valéry, 34293 Montpellier 5, France
| | - Sarah L Barker
- Department of Zoology, University of Cambridge, CB2 3EJ, United Kingdom
| | - Luana Maroja
- Department of Biology, Williams College, Williamstown, Massachusetts, 01267
| | - Simon W Baxter
- School of Biological Sciences, University of Adelaide, SA 5005 Australia
| | - Fraser Simpson
- Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, WC1E 6BT, United Kingdom
| | | | - Mathieu Joron
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS - EPHE - Université de Montpellier - Université Paul Valéry, 34293 Montpellier 5, France
| | - James Mallet
- Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, WC1E 6BT, United Kingdom
| | - Kanchon K Dasmahapatra
- Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, WC1E 6BT, United Kingdom
| | - Chris D Jiggins
- Department of Zoology, University of Cambridge, CB2 3EJ, United Kingdom
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34
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Vu GTH, Schmutzer T, Bull F, Cao HX, Fuchs J, Tran TD, Jovtchev G, Pistrick K, Stein N, Pecinka A, Neumann P, Novak P, Macas J, Dear PH, Blattner FR, Scholz U, Schubert I. Comparative Genome Analysis Reveals Divergent Genome Size Evolution in a Carnivorous Plant Genus. THE PLANT GENOME 2015; 8:eplantgenome2015.04.0021. [PMID: 33228273 DOI: 10.3835/plantgenome2015.04.0021] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/19/2015] [Indexed: 06/11/2023]
Abstract
The C-value paradox remains incompletely resolved after >40 yr and is exemplified by 2,350-fold variation in genome sizes of flowering plants. The carnivorous Lentibulariaceae genus Genlisea, displaying a 25-fold range of genome sizes, is a promising subject to study mechanisms and consequences of evolutionary genome size variation. Applying genomic, phylogenetic, and cytogenetic approaches, we uncovered bidirectional genome size evolution within the genus Genlisea. The Genlisea nigrocaulis Steyerm. genome (86 Mbp) has probably shrunk by retroelement silencing and deletion-biased double-strand break (DSB) repair, from an ancestral size of 400 to 800 Mbp to become one of the smallest among flowering plants. The G. hispidula Stapf genome has expanded by whole-genome duplication (WGD) and retrotransposition to 1550 Mbp. Genlisea hispidula became allotetraploid after the split from the G. nigrocaulis clade ∼29 Ma. Genlisea pygmaea A. St.-Hil. (179 Mbp), a close relative of G. nigrocaulis, proved to be a recent (auto)tetraploid. Our analyses suggest a common ancestor of the genus Genlisea with an intermediate 1C value (400-800 Mbp) and subsequent rapid genome size evolution in opposite directions. Many abundant repeats of the larger genome are absent in the smaller, casting doubt on their functionality for the organism, while recurrent WGD seems to safeguard against the loss of essential elements in the face of genome shrinkage. We cannot identify any consistent differences in habitat or life strategy that correlate with genome size changes, raising the possibility that these changes may be selectively neutral.
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Affiliation(s)
- Giang T H Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Max Planck Institute for Plant Breeding Research (MPIPZ), Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Thomas Schmutzer
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Fabian Bull
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Hieu X Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Jörg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Trung D Tran
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Gabriele Jovtchev
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Institute for Biodiversity and Ecosystem Research, 2 Yurii Gagarin Street, Sofia, 1113, Bulgaria
| | - Klaus Pistrick
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Ales Pecinka
- Max Planck Institute for Plant Breeding Research (MPIPZ), Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Pavel Neumann
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Petr Novak
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Jiri Macas
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Paul H Dear
- MRC Lab. of Molecular Biology, Francis Crick Ave., Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Frank R Blattner
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany
| | - Uwe Scholz
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Faculty of Science and Central European Institute of Technology, Masaryk Univ., 61137, Brno, Czech Republic
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35
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Hara Y. Tempo and mode of genomic mutations unveil human evolutionary history. Genes Genet Syst 2015; 90:123-31. [PMID: 26510567 DOI: 10.1266/ggs.90.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mutations that have occurred in human genomes provide insight into various aspects of evolutionary history such as speciation events and degrees of natural selection. Comparing genome sequences between human and great apes or among humans is a feasible approach for inferring human evolutionary history. Recent advances in high-throughput or so-called 'next-generation' DNA sequencing technologies have enabled the sequencing of thousands of individual human genomes, as well as a variety of reference genomes of hominids, many of which are publicly available. These sequence data can help to unveil the detailed demographic history of the lineage leading to humans as well as the explosion of modern human population size in the last several thousand years. In addition, high-throughput sequencing illustrates the tempo and mode of de novo mutations, which are producing human genetic variation at this moment. Pedigree-based human genome sequencing has shown that mutation rates vary significantly across the human genome. These studies have also provided an improved timescale of human evolution, because the mutation rate estimated from pedigree analysis is half that estimated from traditional analyses based on molecular phylogeny. Because of the dramatic reduction in sequencing cost, sequencing on-demand samples designed for specific studies is now also becoming popular. To produce data of sufficient quality to meet the requirements of the study, it is necessary to set an explicit sequencing plan that includes the choice of sample collection methods, sequencing platforms, and number of sequence reads.
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Affiliation(s)
- Yuichiro Hara
- Phyloinformatics Unit, RIKEN Center for Life Science Technologies
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36
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Kelly LJ, Renny‐Byfield S, Pellicer J, Macas J, Novák P, Neumann P, Lysak MA, Day PD, Berger M, Fay MF, Nichols RA, Leitch AR, Leitch IJ. Analysis of the giant genomes of Fritillaria (Liliaceae) indicates that a lack of DNA removal characterizes extreme expansions in genome size. THE NEW PHYTOLOGIST 2015; 208:596-607. [PMID: 26061193 PMCID: PMC4744688 DOI: 10.1111/nph.13471] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 04/20/2015] [Indexed: 05/18/2023]
Abstract
Plants exhibit an extraordinary range of genome sizes, varying by > 2000-fold between the smallest and largest recorded values. In the absence of polyploidy, changes in the amount of repetitive DNA (transposable elements and tandem repeats) are primarily responsible for genome size differences between species. However, there is ongoing debate regarding the relative importance of amplification of repetitive DNA versus its deletion in governing genome size. Using data from 454 sequencing, we analysed the most repetitive fraction of some of the largest known genomes for diploid plant species, from members of Fritillaria. We revealed that genomic expansion has not resulted from the recent massive amplification of just a handful of repeat families, as shown in species with smaller genomes. Instead, the bulk of these immense genomes is composed of highly heterogeneous, relatively low-abundance repeat-derived DNA, supporting a scenario where amplified repeats continually accumulate due to infrequent DNA removal. Our results indicate that a lack of deletion and low turnover of repetitive DNA are major contributors to the evolution of extremely large genomes and show that their size cannot simply be accounted for by the activity of a small number of high-abundance repeat families.
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Affiliation(s)
- Laura J. Kelly
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
| | - Simon Renny‐Byfield
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
- Department of Plant SciencesUniversity of California DavisDavisCA95616USA
| | - Jaume Pellicer
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
| | - Jiří Macas
- Biology Centre CASInstitute of Plant Molecular BiologyCZ‐37005České BudějoviceCzech Republic
| | - Petr Novák
- Biology Centre CASInstitute of Plant Molecular BiologyCZ‐37005České BudějoviceCzech Republic
| | - Pavel Neumann
- Biology Centre CASInstitute of Plant Molecular BiologyCZ‐37005České BudějoviceCzech Republic
| | - Martin A. Lysak
- Plant Cytogenomics Research GroupCEITEC – Central European Institute of TechnologyMasaryk UniversityKamenice 5CZ‐62500BrnoCzech Republic
| | - Peter D. Day
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
| | - Madeleine Berger
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
- School of Biological and Biomedical SciencesDurham UniversitySouth RoadDurhamDH1 3LEUK
- Rothamsted ResearchWest CommonHarpendenHertfordshireAL5 2JQUK
| | - Michael F. Fay
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
| | - Richard A. Nichols
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
| | - Andrew R. Leitch
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonE1 4NSUK
| | - Ilia J. Leitch
- Jodrell LaboratoryRoyal Botanic GardensKewRichmondTW9 3DSUK
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Schmid M, Smith J, Burt DW, Aken BL, Antin PB, Archibald AL, Ashwell C, Blackshear PJ, Boschiero C, Brown CT, Burgess SC, Cheng HH, Chow W, Coble DJ, Cooksey A, Crooijmans RPMA, Damas J, Davis RVN, de Koning DJ, Delany ME, Derrien T, Desta TT, Dunn IC, Dunn M, Ellegren H, Eöry L, Erb I, Farré M, Fasold M, Fleming D, Flicek P, Fowler KE, Frésard L, Froman DP, Garceau V, Gardner PP, Gheyas AA, Griffin DK, Groenen MAM, Haaf T, Hanotte O, Hart A, Häsler J, Hedges SB, Hertel J, Howe K, Hubbard A, Hume DA, Kaiser P, Kedra D, Kemp SJ, Klopp C, Kniel KE, Kuo R, Lagarrigue S, Lamont SJ, Larkin DM, Lawal RA, Markland SM, McCarthy F, McCormack HA, McPherson MC, Motegi A, Muljo SA, Münsterberg A, Nag R, Nanda I, Neuberger M, Nitsche A, Notredame C, Noyes H, O'Connor R, O'Hare EA, Oler AJ, Ommeh SC, Pais H, Persia M, Pitel F, Preeyanon L, Prieto Barja P, Pritchett EM, Rhoads DD, Robinson CM, Romanov MN, Rothschild M, Roux PF, Schmidt CJ, Schneider AS, Schwartz MG, Searle SM, Skinner MA, Smith CA, Stadler PF, Steeves TE, Steinlein C, Sun L, Takata M, Ulitsky I, Wang Q, Wang Y, Warren WC, Wood JMD, Wragg D, Zhou H. Third Report on Chicken Genes and Chromosomes 2015. Cytogenet Genome Res 2015; 145:78-179. [PMID: 26282327 PMCID: PMC5120589 DOI: 10.1159/000430927] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Michael Schmid
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
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Xiao B, Cui LQ, Chen TM, Lian B. Stochastic effects in adaptive reconstruction of body damage: implied the creativity of natural selection. J Cell Mol Med 2015; 19:2521-9. [PMID: 26153081 PMCID: PMC4627558 DOI: 10.1111/jcmm.12647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 06/02/2015] [Indexed: 12/28/2022] Open
Abstract
After an injury occurs, mechanical/biochemical loads on muscles influence the composition and structure of recovering muscles; this effect likely occurs in other tissues, cells and biological molecules as well owing to the similarity, interassociation and interaction among biochemical reactions and molecules. The 'damage and reconstruction' model provides an explanation for how an ideal cytoarchitecture is created by reducing components not suitable for bearing loads; in this model, adaptive changes are induced by promoting the stochasticity of biochemical reactions. Biochemical and mechanical loads can direct the stochasticity of biochemical reactions, which can in turn induce cellular changes. Thus, mechanical and biochemical loads, under natural selection pressure, modify the direction of cell- and tissue-level changes and guide the formation of new structures and traits, thereby influencing microevolution. In summary, the 'damage and reconstruction' model accounts for the role of natural selection in the formation of new organisms, helps explain punctuated equilibrium, and illustrates how macroevolution arises from microevolution.
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Affiliation(s)
- Bo Xiao
- Key Laboratory for Ecology and Pollution Control of Coastal Wetlands, School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, China
| | - Li-Qiang Cui
- Key Laboratory for Ecology and Pollution Control of Coastal Wetlands, School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, China
| | - Tian-Ming Chen
- Key Laboratory for Ecology and Pollution Control of Coastal Wetlands, School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, China
| | - Bin Lian
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Key Lab for Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, China
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Gossmann TI, Santure AW, Sheldon BC, Slate J, Zeng K. Highly variable recombinational landscape modulates efficacy of natural selection in birds. Genome Biol Evol 2015; 6:2061-75. [PMID: 25062920 PMCID: PMC4231635 DOI: 10.1093/gbe/evu157] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Determining the rate of protein evolution and identifying the causes of its variation across the genome are powerful ways to understand forces that are important for genome evolution. By using a multitissue transcriptome data set from great tit (Parus major), we analyzed patterns of molecular evolution between two passerine birds, great tit and zebra finch (Taeniopygia guttata), using the chicken genome (Gallus gallus) as an outgroup. We investigated whether a special feature of avian genomes, the highly variable recombinational landscape, modulates the efficacy of natural selection through the effects of Hill-Robertson interference, which predicts that selection should be more effective in removing deleterious mutations and incorporating beneficial mutations in high-recombination regions than in low-recombination regions. In agreement with these predictions, genes located in low-recombination regions tend to have a high proportion of neutrally evolving sites and relaxed selective constraint on sites subject to purifying selection, whereas genes that show strong support for past episodes of positive selection appear disproportionally in high-recombination regions. There is also evidence that genes located in high-recombination regions tend to have higher gene expression specificity than those located in low-recombination regions. Furthermore, more compact genes (i.e., those with fewer/shorter introns or shorter proteins) evolve faster than less compact ones. In sum, our results demonstrate that transcriptome sequencing is a powerful method to answer fundamental questions about genome evolution in nonmodel organisms.
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Affiliation(s)
- Toni I Gossmann
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
| | - Anna W Santure
- Department of Animal and Plant Sciences, University of Sheffield, United KingdomSchool of Biological Sciences, University of Auckland, New Zealand
| | - Ben C Sheldon
- Edward Grey Institute, Department of Zoology, University of Oxford, United Kingdom
| | - Jon Slate
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
| | - Kai Zeng
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
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40
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Sun C, Mueller RL. Hellbender genome sequences shed light on genomic expansion at the base of crown salamanders. Genome Biol Evol 2015; 6:1818-29. [PMID: 25115007 PMCID: PMC4122941 DOI: 10.1093/gbe/evu143] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Among animals, genome sizes range from 20 Mb to 130 Gb, with 380-fold variation across vertebrates. Most of the largest vertebrate genomes are found in salamanders, an amphibian clade of 660 species. Thus, salamanders are an important system for studying causes and consequences of genomic gigantism. Previously, we showed that plethodontid salamander genomes accumulate higher levels of long terminal repeat (LTR) retrotransposons than do other vertebrates, although the evolutionary origins of such sequences remained unexplored. We also showed that some salamanders in the family Plethodontidae have relatively slow rates of DNA loss through small insertions and deletions. Here, we present new data from Cryptobranchus alleganiensis, the hellbender. Cryptobranchus and Plethodontidae span the basal phylogenetic split within salamanders; thus, analyses incorporating these taxa can shed light on the genome of the ancestral crown salamander lineage, which underwent expansion. We show that high levels of LTR retrotransposons likely characterize all crown salamanders, suggesting that disproportionate expansion of this transposable element (TE) class contributed to genomic expansion. Phylogenetic and age distribution analyses of salamander LTR retrotransposons indicate that salamanders' high TE levels reflect persistence and diversification of ancestral TEs rather than horizontal transfer events. Finally, we show that relatively slow DNA loss rates through small indels likely characterize all crown salamanders, suggesting that a decreased DNA loss rate contributed to genomic expansion at the clade's base. Our identification of shared genomic features across phylogenetically distant salamanders is a first step toward identifying the evolutionary processes underlying accumulation and persistence of high levels of repetitive sequence in salamander genomes.
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41
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Ågren JA, Greiner S, Johnson MTJ, Wright SI. No evidence that sex and transposable elements drive genome size variation in evening primroses. Evolution 2015; 69:1053-62. [PMID: 25690700 DOI: 10.1111/evo.12627] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 01/13/2015] [Indexed: 01/05/2023]
Abstract
Genome size varies dramatically across species, but despite an abundance of attention there is little agreement on the relative contributions of selective and neutral processes in governing this variation. The rate of sex can potentially play an important role in genome size evolution because of its effect on the efficacy of selection and transmission of transposable elements (TEs). Here, we used a phylogenetic comparative approach and whole genome sequencing to investigate the contribution of sex and TE content to genome size variation in the evening primrose (Oenothera) genus. We determined genome size using flow cytometry for 30 species that vary in genetic system and find that variation in sexual/asexual reproduction cannot explain the almost twofold variation in genome size. Moreover, using whole genome sequences of three species of varying genome sizes and reproductive system, we found that genome size was not associated with TE abundance; instead the larger genomes had a higher abundance of simple sequence repeats. Although it has long been clear that sexual reproduction may affect various aspects of genome evolution in general and TE evolution in particular, it does not appear to have played a major role in genome size evolution in the evening primroses.
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Affiliation(s)
- J Arvid Ågren
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada.
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42
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Tennessen JA, Théron A, Marine M, Yeh JY, Rognon A, Blouin MS. Hyperdiverse gene cluster in snail host conveys resistance to human schistosome parasites. PLoS Genet 2015; 11:e1005067. [PMID: 25775214 PMCID: PMC4361660 DOI: 10.1371/journal.pgen.1005067] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/10/2015] [Indexed: 01/07/2023] Open
Abstract
Schistosomiasis, a neglected global pandemic, may be curtailed by blocking transmission of the parasite via its intermediate hosts, aquatic snails. Elucidating the genetic basis of snail-schistosome interaction is a key to this strategy. Here we map a natural parasite-resistance polymorphism from a Caribbean population of the snail Biomphalaria glabrata. In independent experimental evolution lines, RAD genotyping shows that the same genomic region responds to selection for resistance to the parasite Schistosoma mansoni. A dominant allele in this region conveys an 8-fold decrease in the odds of infection. Fine-mapping and RNA-Seq characterization reveal a <1Mb region, the Guadeloupe Resistance Complex (GRC), with 15 coding genes. Seven genes are single-pass transmembrane proteins with putative immunological roles, most of which show strikingly high nonsynonymous divergence (5-10%) among alleles. High linkage disequilibrium among three intermediate-frequency (>25%) haplotypes across the GRC, a significantly non-neutral pattern, suggests that balancing selection maintains diversity at the GRC. Thus, the GRC resembles immune gene complexes seen in other taxa and is likely involved in parasite recognition. The GRC is a potential target for controlling transmission of schistosomiasis, including via genetic manipulation of snails. Schistosomes are water-borne blood-flukes that are transmitted by snail vectors. They infect over 200 million people in more than 70 countries and cause severe and chronic disability. Snails naturally vary in resistance to this parasite even within species, so bolstering snail resistance in the wild would block transmission. We artificially selected snails for resistance and observed a rapid evolutionary response, with the greatest change occurring in the same genomic region in two independent trials. We subsequently confirmed that the selected haplotype conveys resistance to infection by schistosomes. The extraordinarily high sequence divergence among haplotypes in this region appears to be elevated due to ongoing natural selection, likely via host-parasite co-evolution. We observed the highest variation in genes encoding putative parasite recognition proteins, suggesting that these control the resistance phenotype in a manner reminiscent of immune gene complexes in other taxa. Thus, this gene cluster presents a potential new target to interfere with parasite transmission at the vector stage.
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Affiliation(s)
- Jacob A. Tennessen
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - André Théron
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Perpignan, France
| | - Melanie Marine
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jan-Ying Yeh
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Anne Rognon
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Perpignan, France
| | - Michael S. Blouin
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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43
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Frahry MB, Sun C, Chong RA, Mueller RL. Low levels of LTR retrotransposon deletion by ectopic recombination in the gigantic genomes of salamanders. J Mol Evol 2015; 80:120-9. [PMID: 25608479 DOI: 10.1007/s00239-014-9663-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/30/2014] [Indexed: 11/25/2022]
Abstract
Across the tree of life, species vary dramatically in nuclear genome size. Mutations that add or remove sequences from genomes-insertions or deletions, or indels-are the ultimate source of this variation. Differences in the tempo and mode of insertion and deletion across taxa have been proposed to contribute to evolutionary diversity in genome size. Among vertebrates, most of the largest genomes are found within the salamanders, an amphibian clade with genome sizes ranging from ~14 to ~120 Gb. Salamander genomes have been shown to experience slower rates of DNA loss through small (i.e., <30 bp) deletions than do other vertebrate genomes. However, no studies have addressed DNA loss from salamander genomes resulting from larger deletions. Here, we focus on one type of large deletion-ectopic-recombination-mediated removal of LTR retrotransposon sequences. In ectopic recombination, double-strand breaks are repaired using a "wrong" (i.e., ectopic, or non-allelic) template sequence-typically another locus of similar sequence. When breaks occur within the LTR portions of LTR retrotransposons, ectopic-recombination-mediated repair can produce deletions that remove the internal transposon sequence and the equivalent of one of the two LTR sequences. These deletions leave a signature in the genome-a solo LTR sequence. We compared levels of solo LTRs in the genomes of four salamander species with levels present in five vertebrates with smaller genomes. Our results demonstrate that salamanders have low levels of solo LTRs, suggesting that ectopic-recombination-mediated deletion of LTR retrotransposons occurs more slowly than in other vertebrates with smaller genomes.
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Affiliation(s)
- Matthew Blake Frahry
- Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
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Smeds L, Kawakami T, Burri R, Bolivar P, Husby A, Qvarnström A, Uebbing S, Ellegren H. Genomic identification and characterization of the pseudoautosomal region in highly differentiated avian sex chromosomes. Nat Commun 2014; 5:5448. [PMID: 25378102 PMCID: PMC4272252 DOI: 10.1038/ncomms6448] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 09/30/2014] [Indexed: 02/07/2023] Open
Abstract
The molecular characteristics of the pseudoautosomal region (PAR) of sex chromosomes
remain elusive. Despite significant genome-sequencing efforts, the PAR of highly
differentiated avian sex chromosomes remains to be identified. Here we use linkage
analysis together with whole-genome re-sequencing to uncover the 630-kb PAR of an
ecological model species, the collared flycatcher. The PAR contains 22 protein-coding
genes and is GC rich. The genetic length is 64 cM in female meiosis, consistent
with an obligate crossing-over event. Recombination is concentrated to a hotspot region,
with an extreme rate of >700 cM/Mb in a 67-kb segment. We find no signatures
of sexual antagonism and propose that sexual antagonism may have limited influence on
PAR sequences when sex chromosomes are nearly fully differentiated and when a
recombination hotspot region is located close to the PAR boundary. Our results
demonstrate that a very small PAR suffices to ensure homologous recombination and proper
segregation of sex chromosomes during meiosis. The genetic basis of sex chromosome pseudoautosomal regions (PAR) in
organisms with female heterogamety is largely unknown. Smeds et al. provide the
first molecular characterization of the PAR in birds with differentiated sex chromosomes
and show a potential recombination hotspot and no evidence for strong sexual antagonism in
this region.
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Affiliation(s)
- Linnéa Smeds
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Takeshi Kawakami
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Reto Burri
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Paulina Bolivar
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Arild Husby
- 1] Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden [2] Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Anna Qvarnström
- Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Severin Uebbing
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Hans Ellegren
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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45
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Metcalfe CJ, Casane D. Accommodating the load: The transposable element content of very large genomes. Mob Genet Elements 2014; 3:e24775. [PMID: 24616835 PMCID: PMC3943481 DOI: 10.4161/mge.24775] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/20/2013] [Accepted: 04/22/2013] [Indexed: 01/31/2023] Open
Abstract
Very large genomes, that is, those above 20 Gb, are rare but widely distributed throughout the eukaryotes. They are found within the diatoms, dinoflagellates, metazoans and green plants, but so far have not been found in the excavates. There is a known positive correlation between genome size and the proportion of the genome composed of transposable elements (TEs). Very large genomes may therefore be expected to be almost entirely composed of TEs. Of the large genomes examined, in the angiosperms, gymnosperms and the dinoflagellates only a small portion of the genome was identified as TEs, most of these genomes were unidentified and may be novel or diverse TEs. In the salamanders and lungfish, 25 to 47% of the genome were identifiable retrotransposons, that is, TEs that copy themselves before insertion. However, the predominant class of TEs found in the lungfish was not the same as that found in the salamanders. The little data we have at the moment suggests therefore that the diversity and abundance of TEs is variable between taxa with large genomes, similar to patterns found in taxa with smaller genomes. Based on results from the human genome, we suggest that the ‘missing’ portion of the lungfish and salamander genomes are old, highly divergent, and therefore inactive copies of TEs. The data available indicate that, unlike plants with large genomes, neither the lungfish nor the salamanders show an increased risk of extinction. Based on a slow rate of DNA loss in salamanders it has been suggested that the large salamander genome is the result of run-away genome expansion involving genome size increases via TE proliferation associated with reduced recombination rate. We know of no studies on DNA loss or recombination rates in lungfish genomes, however a similar scenario could describe the process of genome expansion in the lungfish. A series of waves of TE transposition and sequence decay would describe the pattern of TE content seen in both the lungfish and the salamanders. The lungfish and salamanders, therefore, may accommodate their large load of TEs because these TEs have accumulated gradually over a long period of time and have been subject to inactivation and decay.
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Affiliation(s)
- Cushla J Metcalfe
- Instituto de Biociências; Universidade de São Paulo; Cidade Universitária; São Paulo, Brazil
| | - Didier Casane
- Laboratoire Evolution Génomes et Spéciation; UPR9034 CNRS; Gif-sur-Yvette, France ; Université Paris Diderot; Sorbonne Paris Cité, France
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Pellicer J, Kelly LJ, Leitch IJ, Zomlefer WB, Fay MF. A universe of dwarfs and giants: genome size and chromosome evolution in the monocot family Melanthiaceae. THE NEW PHYTOLOGIST 2014; 201:1484-1497. [PMID: 24299166 DOI: 10.1111/nph.12617] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 10/30/2013] [Indexed: 05/22/2023]
Abstract
• Since the occurrence of giant genomes in angiosperms is restricted to just a few lineages, identifying where shifts towards genome obesity have occurred is essential for understanding the evolutionary mechanisms triggering this process. • Genome sizes were assessed using flow cytometry in 79 species and new chromosome numbers were obtained. Phylogenetically based statistical methods were applied to infer ancestral character reconstructions of chromosome numbers and nuclear DNA contents. • Melanthiaceae are the most diverse family in terms of genome size, with C-values ranging more than 230-fold. Our data confirmed that giant genomes are restricted to tribe Parideae, with most extant species in the family characterized by small genomes. Ancestral genome size reconstruction revealed that the most recent common ancestor (MRCA) for the family had a relatively small genome (1C = 5.37 pg). Chromosome losses and polyploidy are recovered as the main evolutionary mechanisms generating chromosome number change. • Genome evolution in Melanthiaceae has been characterized by a trend towards genome size reduction, with just one episode of dramatic DNA accumulation in Parideae. Such extreme contrasting profiles of genome size evolution illustrate the key role of transposable elements and chromosome rearrangements in driving the evolution of plant genomes.
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Affiliation(s)
- Jaume Pellicer
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
| | - Laura J Kelly
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK
| | - Ilia J Leitch
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
| | - Wendy B Zomlefer
- Department of Plant Biology, 2502 Plant Sciences, University of Georgia, Athens, GA, 30602-7271, USA
| | - Michael F Fay
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, UK
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Weber CC, Boussau B, Romiguier J, Jarvis ED, Ellegren H. Evidence for GC-biased gene conversion as a driver of between-lineage differences in avian base composition. Genome Biol 2014; 15:549. [PMID: 25496599 PMCID: PMC4290106 DOI: 10.1186/s13059-014-0549-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 11/19/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND While effective population size (Ne) and life history traits such as generation time are known to impact substitution rates, their potential effects on base composition evolution are less well understood. GC content increases with decreasing body mass in mammals, consistent with recombination-associated GC biased gene conversion (gBGC) more strongly impacting these lineages. However, shifts in chromosomal architecture and recombination landscapes between species may complicate the interpretation of these results. In birds, interchromosomal rearrangements are rare and the recombination landscape is conserved, suggesting that this group is well suited to assess the impact of life history on base composition. RESULTS Employing data from 45 newly and 3 previously sequenced avian genomes covering a broad range of taxa, we found that lineages with large populations and short generations exhibit higher GC content. The effect extends to both coding and non-coding sites, indicating that it is not due to selection on codon usage. Consistent with recombination driving base composition, GC content and heterogeneity were positively correlated with the rate of recombination. Moreover, we observed ongoing increases in GC in the majority of lineages. CONCLUSIONS Our results provide evidence that gBGC may drive patterns of nucleotide composition in avian genomes and are consistent with more effective gBGC in large populations and a greater number of meioses per unit time; that is, a shorter generation time. Thus, in accord with theoretical predictions, base composition evolution is substantially modulated by species life history.
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Affiliation(s)
- Claudia C Weber
- />Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Bastien Boussau
- />Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR5558 Villeurbanne, France
| | | | - Erich D Jarvis
- />Department of Neurobiology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC USA
| | - Hans Ellegren
- />Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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48
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Kvikstad EM, Duret L. Strong heterogeneity in mutation rate causes misleading hallmarks of natural selection on indel mutations in the human genome. Mol Biol Evol 2013; 31:23-36. [PMID: 24113537 PMCID: PMC3879449 DOI: 10.1093/molbev/mst185] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Elucidating the mechanisms of mutation accumulation and fixation is critical to understand the nature of genetic variation and its contribution to genome evolution. Of particular interest is the effect of insertions and deletions (indels) on the evolution of genome landscapes. Recent population-scaled sequencing efforts provide unprecedented data for analyzing the relative impact of selection versus nonadaptive forces operating on indels. Here, we combined McDonald-Kreitman tests with the analysis of derived allele frequency spectra to investigate the dynamics of allele fixation of short (1-50 bp) indels in the human genome. Our analyses revealed apparently higher fixation probabilities for insertions than deletions. However, this fixation bias is not consistent with either selection or biased gene conversion and varies with local mutation rate, being particularly pronounced at indel hotspots. Furthermore, we identified an unprecedented number of loci with evidence for multiple indel events in the primate phylogeny. Even in nonrepetitive sequence contexts (a priori not prone to indel mutations), such loci are 60-fold more frequent than expected according to a model of uniform indel mutation rate. This provides evidence of as yet unidentified cryptic indel hotspots. We propose that indel homoplasy, at known and cryptic hotspots, produces systematic errors in determination of ancestral alleles via parsimony and advise caution interpreting classic selection tests given the strong heterogeneity in indel rates across the genome. These results will have great impact on studies seeking to infer evolutionary forces operating on indels observed in closely related species, because such mutations are traditionally presumed homoplasy-free.
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Affiliation(s)
- Erika M Kvikstad
- Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, CNRS, Université Lyon 1, Villeurbanne, France
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Targeted sequence capture provides insight into genome structure and genetics of male sterility in a gynodioecious diploid strawberry, Fragaria vesca ssp. bracteata (Rosaceae). G3-GENES GENOMES GENETICS 2013; 3:1341-51. [PMID: 23749450 PMCID: PMC3737174 DOI: 10.1534/g3.113.006288] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Gynodioecy is a sexual system wherein females coexist with hermaphrodites. It is of interest not only because male-sterile plants are advantageous in plant breeding but also because it can be a crucial step in the evolutionary transition to entirely separate sexes (dioecy) from a hermaphroditic ancestor. The gynodioecious diploid wild strawberry, Fragaria vesca ssp. bracteata (Rosaceae), is a member of a clade with both dioecious and cultivated species, making it an ideal model in which to study the genetics of male sterility. To create a genetic map of F. v. ssp. bracteata, we identified informative polymorphisms from genomic sequencing (3−5x coverage) of two outbred plants from the same population. Using targeted enrichment, we sequenced 200 bp surrounding each of 6575 polymorphisms in 48 F1 offspring, yielding genotypes at 98% of targeted sites with mean coverage >100x, plus more than 600-kb high-coverage nontargeted sequence. With the resulting linkage map of 7802 stringently filtered markers (5417 targeted), we assessed recombination rates and genomic incongruities. Consistent with past work in strawberries, male sterility is dominant, segregates 1:1, and maps to a single location in the female. Further mapping an additional 55 offspring places male sterility in a gene-dense, 338-kb region of chromosome 4. The region is not syntenic with the sex-determining regions in the closely related octoploids, F. chiloensis and F. virginiana, suggesting either independent origins or translocation. The 57 genes in this region do not include protein families known to control male sterility and thus suggest alternate mechanisms for the suppression of male function.
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Díez CM, Gaut BS, Meca E, Scheinvar E, Montes-Hernandez S, Eguiarte LE, Tenaillon MI. Genome size variation in wild and cultivated maize along altitudinal gradients. THE NEW PHYTOLOGIST 2013; 199:264-276. [PMID: 23550586 PMCID: PMC4119021 DOI: 10.1111/nph.12247] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 02/20/2013] [Indexed: 05/18/2023]
Abstract
It is still an open question as to whether genome size (GS) variation is shaped by natural selection. One approach to address this question is a population-level survey that assesses both the variation in GS and the relationship of GS to ecological variants. We assessed GS in Zea mays, a species that includes the cultivated crop, maize, and its closest wild relatives, the teosintes. We measured GS in five plants of each of 22 maize landraces and 21 teosinte populations from Mexico sampled from parallel altitudinal gradients. GS was significantly smaller in landraces than in teosintes, but the largest component of GS variation was among landraces and among populations. In maize, GS correlated negatively with altitude; more generally, the best GS predictors were linked to geography. By contrast, GS variation in teosintes was best explained by temperature and precipitation. Overall, our results further document the size flexibility of the Zea genome, but also point to a drastic shift in patterns of GS variation since domestication. We argue that such patterns may reflect the indirect action of selection on GS, through a multiplicity of phenotypes and life-history traits.
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Affiliation(s)
- Concepción M Díez
- Department of Ecology and Evolutionary Biology, UC Irvine, Irvine, CA, 92697, USA
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, UC Irvine, Irvine, CA, 92697, USA
| | - Esteban Meca
- Department of Mathematics, UC Irvine, Irvine, CA, 92607, USA
| | - Enrique Scheinvar
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, CP 04510, Mexico City, Mexico
| | - Salvador Montes-Hernandez
- Campo Experimental Bajío, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, CP 38110, Celaya, Guanajuato, Mexico
| | - Luis E Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, CP 04510, Mexico City, Mexico
| | - Maud I Tenaillon
- CNRS, UMR de Génétique Végétale, INRA/CNRS/Univ Paris-Sud/AgroParisTech, Ferme du Moulon, Gif-sur-Yvette, France
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