1
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Pliota P, Marvanova H, Koreshova A, Kaufman Y, Tikanova P, Krogull D, Hagmüller A, Widen SA, Handler D, Gokcezade J, Duchek P, Brennecke J, Ben-David E, Burga A. Selfish conflict underlies RNA-mediated parent-of-origin effects. Nature 2024; 628:122-129. [PMID: 38448590 PMCID: PMC10990930 DOI: 10.1038/s41586-024-07155-z] [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: 11/21/2022] [Accepted: 02/02/2024] [Indexed: 03/08/2024]
Abstract
Genomic imprinting-the non-equivalence of maternal and paternal genomes-is a critical process that has evolved independently in many plant and mammalian species1,2. According to kinship theory, imprinting is the inevitable consequence of conflictive selective forces acting on differentially expressed parental alleles3,4. Yet, how these epigenetic differences evolve in the first place is poorly understood3,5,6. Here we report the identification and molecular dissection of a parent-of-origin effect on gene expression that might help to clarify this fundamental question. Toxin-antidote elements (TAs) are selfish elements that spread in populations by poisoning non-carrier individuals7-9. In reciprocal crosses between two Caenorhabditis tropicalis wild isolates, we found that the slow-1/grow-1 TA is specifically inactive when paternally inherited. This parent-of-origin effect stems from transcriptional repression of the slow-1 toxin by the PIWI-interacting RNA (piRNA) host defence pathway. The repression requires PIWI Argonaute and SET-32 histone methyltransferase activities and is transgenerationally inherited via small RNAs. Remarkably, when slow-1/grow-1 is maternally inherited, slow-1 repression is halted by a translation-independent role of its maternal mRNA. That is, slow-1 transcripts loaded into eggs-but not SLOW-1 protein-are necessary and sufficient to counteract piRNA-mediated repression. Our findings show that parent-of-origin effects can evolve by co-option of the piRNA pathway and hinder the spread of selfish genes that require sex for their propagation.
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Affiliation(s)
- Pinelopi Pliota
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Hana Marvanova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Alevtina Koreshova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Yotam Kaufman
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Polina Tikanova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Daniel Krogull
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Andreas Hagmüller
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Sonya A Widen
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Dominik Handler
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Joseph Gokcezade
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Peter Duchek
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Julius Brennecke
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Eyal Ben-David
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
- Illumina Artificial Intelligence Laboratory, Illumina, San Diego, CA, USA
| | - Alejandro Burga
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria.
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2
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Delmore K, Justen H, Kay KM, Kitano J, Moyle LC, Stelkens R, Streisfeld MA, Yamasaki YY, Ross J. Genomic Approaches Are Improving Taxonomic Representation in Genetic Studies of Speciation. Cold Spring Harb Perspect Biol 2024; 16:a041438. [PMID: 37848243 PMCID: PMC10835617 DOI: 10.1101/cshperspect.a041438] [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] [Indexed: 10/19/2023]
Abstract
Until recently, our understanding of the genetics of speciation was limited to a narrow group of model species with a specific set of characteristics that made genetic analysis feasible. Rapidly advancing genomic technologies are eliminating many of the distinctions between laboratory and natural systems. In light of these genomic developments, we review the history of speciation genetics, advances that have been gleaned from model and non-model organisms, the current state of the field, and prospects for broadening the diversity of taxa included in future studies. Responses to a survey of speciation scientists across the world reveal the ongoing division between the types of questions that are addressed in model and non-model organisms. To bridge this gap, we suggest integrating genetic studies from model systems that can be reared in the laboratory or greenhouse with genomic studies in related non-models where extensive ecological knowledge exists.
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Affiliation(s)
- Kira Delmore
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Hannah Justen
- Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, California 95060, USA
| | - Jun Kitano
- Ecological Genetics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Leonie C Moyle
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Rike Stelkens
- Division of Population Genetics, Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
| | - Matthew A Streisfeld
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403, USA
| | - Yo Y Yamasaki
- Ecological Genetics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Joseph Ross
- Department of Biology, California State University, Fresno, California 93740, USA
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3
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Woodruff GC, Willis JH, Phillips PC. Patterns of Genomic Diversity in a Fig-Associated Close Relative of Caenorhabditis elegans. Genome Biol Evol 2024; 16:evae020. [PMID: 38302111 PMCID: PMC10883733 DOI: 10.1093/gbe/evae020] [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: 08/22/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/03/2024] Open
Abstract
The evolution of reproductive mode is expected to have profound impacts on the genetic composition of populations. At the same time, ecological interactions can generate close associations among species, which can in turn generate a high degree of overlap in their spatial distributions. Caenorhabditis elegans is a hermaphroditic nematode that has enabled extensive advances in developmental genetics. Caenorhabditis inopinata, the sister species of C. elegans, is a gonochoristic nematode that thrives in figs and obligately disperses on fig wasps. Here, we describe patterns of genomic diversity in C. inopinata. We performed RAD-seq on individual worms isolated from the field across three Okinawan island populations. C. inopinata is about five times more diverse than C. elegans. Additionally, C. inopinata harbors greater differences in diversity among functional genomic regions (such as between genic and intergenic sequences) than C. elegans. Conversely, C. elegans harbors greater differences in diversity between high-recombining chromosome arms and low-recombining chromosome centers than C. inopinata. FST is low among island population pairs, and clear population structure could not be easily detected among islands, suggesting frequent migration of wasps between islands. These patterns of population differentiation appear comparable with those previously reported in its fig wasp vector. These results confirm many theoretical population genetic predictions regarding the evolution of reproductive mode and suggest C. inopinata population dynamics may be driven by wasp dispersal. This work sets the stage for future evolutionary genomic studies aimed at understanding the evolution of sex as well as the evolution of ecological interactions.
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Affiliation(s)
- Gavin C Woodruff
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
- Present address: Department of Biology, University of Oklahoma, Norman, OK 73019, USA
| | - John H Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
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4
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Crombie TA, McKeown R, Moya ND, Evans K, Widmayer S, LaGrassa V, Roman N, Tursunova O, Zhang G, Gibson S, Buchanan C, Roberto N, Vieira R, Tanny R, Andersen E. CaeNDR, the Caenorhabditis Natural Diversity Resource. Nucleic Acids Res 2024; 52:D850-D858. [PMID: 37855690 PMCID: PMC10767927 DOI: 10.1093/nar/gkad887] [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: 08/23/2023] [Revised: 09/30/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023] Open
Abstract
Studies of model organisms have provided important insights into how natural genetic differences shape trait variation. These discoveries are driven by the growing availability of genomes and the expansive experimental toolkits afforded to researchers using these species. For example, Caenorhabditis elegans is increasingly being used to identify and measure the effects of natural genetic variants on traits using quantitative genetics. Since 2016, the C. elegans Natural Diversity Resource (CeNDR) has facilitated many of these studies by providing an archive of wild strains, genome-wide sequence and variant data for each strain, and a genome-wide association (GWA) mapping portal for the C. elegans community. Here, we present an updated platform, the Caenorhabditis Natural Diversity Resource (CaeNDR), that enables quantitative genetics and genomics studies across the three Caenorhabditis species: C. elegans, C. briggsae and C. tropicalis. The CaeNDR platform hosts several databases that are continually updated by the addition of new strains, whole-genome sequence data and annotated variants. Additionally, CaeNDR provides new interactive tools to explore natural variation and enable GWA mappings. All CaeNDR data and tools are accessible through a freely available web portal located at caendr.org.
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Affiliation(s)
- Timothy A Crombie
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, USA
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Ryan McKeown
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - Nicolas D Moya
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
- Cell, Molecular, Developmental biology, and Biophysics Graduate Program, ohns Hopkins University, Baltimore, MD, USA
| | - Kathryn S Evans
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Samuel J Widmayer
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Vincent LaGrassa
- Northwestern University Information Technology, Media and Technology Innovation, Northwestern University, Evanston, IL USA
| | - Natalie Roman
- Northwestern University Information Technology, Media and Technology Innovation, Northwestern University, Evanston, IL USA
| | - Orzu Tursunova
- Northwestern University Information Technology, Media and Technology Innovation, Northwestern University, Evanston, IL USA
| | - Gaotian Zhang
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Sophia B Gibson
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Claire M Buchanan
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Nicole M Roberto
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Rodolfo Vieira
- Northwestern University Information Technology, Media and Technology Innovation, Northwestern University, Evanston, IL USA
| | - Robyn E Tanny
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Erik C Andersen
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
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5
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Stevens L, Martínez-Ugalde I, King E, Wagah M, Absolon D, Bancroft R, Gonzalez de la Rosa P, Hall JL, Kieninger M, Kloch A, Pelan S, Robertson E, Pedersen AB, Abreu-Goodger C, Buck AH, Blaxter M. Ancient diversity in host-parasite interaction genes in a model parasitic nematode. Nat Commun 2023; 14:7776. [PMID: 38012132 PMCID: PMC10682056 DOI: 10.1038/s41467-023-43556-w] [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: 05/26/2023] [Accepted: 11/13/2023] [Indexed: 11/29/2023] Open
Abstract
Host-parasite interactions exert strong selection pressures on the genomes of both host and parasite. These interactions can lead to negative frequency-dependent selection, a form of balancing selection that is hypothesised to explain the high levels of polymorphism seen in many host immune and parasite antigen loci. Here, we sequence the genomes of several individuals of Heligmosomoides bakeri, a model parasite of house mice, and Heligmosomoides polygyrus, a closely related parasite of wood mice. Although H. bakeri is commonly referred to as H. polygyrus in the literature, their genomes show levels of divergence that are consistent with at least a million years of independent evolution. The genomes of both species contain hyper-divergent haplotypes that are enriched for proteins that interact with the host immune response. Many of these haplotypes originated prior to the divergence between H. bakeri and H. polygyrus, suggesting that they have been maintained by long-term balancing selection. Together, our results suggest that the selection pressures exerted by the host immune response have played a key role in shaping patterns of genetic diversity in the genomes of parasitic nematodes.
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Affiliation(s)
- Lewis Stevens
- Tree of Life, Wellcome Sanger Institute, Hinxton, UK.
| | - Isaac Martínez-Ugalde
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Erna King
- Tree of Life, Wellcome Sanger Institute, Hinxton, UK
| | - Martin Wagah
- Tree of Life, Wellcome Sanger Institute, Hinxton, UK
| | | | - Rowan Bancroft
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | | | - Jessica L Hall
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | | | | | - Sarah Pelan
- Tree of Life, Wellcome Sanger Institute, Hinxton, UK
| | - Elaine Robertson
- Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Amy B Pedersen
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Cei Abreu-Goodger
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Amy H Buck
- Institute of Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Mark Blaxter
- Tree of Life, Wellcome Sanger Institute, Hinxton, UK.
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6
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You S, Zhao Z, Yu X, Zhu S, Wang J, Lei D, Zhou J, Li J, Chen H, Xiao Y, Chen W, Wang Q, Lu J, Chen K, Zhou C, Zhang X, Cheng Z, Guo X, Ren Y, Zheng X, Liu S, Liu X, Tian Y, Jiang L, Tao D, Wu C, Wan J. A toxin-antidote system contributes to interspecific reproductive isolation in rice. Nat Commun 2023; 14:7528. [PMID: 37980335 PMCID: PMC10657391 DOI: 10.1038/s41467-023-43015-6] [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: 12/06/2022] [Accepted: 09/18/2023] [Indexed: 11/20/2023] Open
Abstract
Breakdown of reproductive isolation facilitates flow of useful trait genes into crop plants from their wild relatives. Hybrid sterility, a major form of reproductive isolation exists between cultivated rice (Oryza sativa) and wild rice (O. meridionalis, Mer). Here, we report the cloning of qHMS1, a quantitative trait locus controlling hybrid male sterility between these two species. Like qHMS7, another locus we cloned previously, qHMS1 encodes a toxin-antidote system, but differs in the encoded proteins, their evolutionary origin, and action time point during pollen development. In plants heterozygous at qHMS1, ~ 50% of pollens carrying qHMS1-D (an allele from cultivated rice) are selectively killed. In plants heterozygous at both qHMS1 and qHMS7, ~ 75% pollens without co-presence of qHMS1-Mer and qHMS7-D are selectively killed, indicating that the antidotes function in a toxin-dependent manner. Our results indicate that different toxin-antidote systems provide stacked reproductive isolation for maintaining species identity and shed light on breakdown of hybrid male sterility.
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Affiliation(s)
- Shimin You
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Zhigang Zhao
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Xiaowen Yu
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Shanshan Zhu
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Jian Wang
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Dekun Lei
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Jiawu Zhou
- Yunnan Seed Laboratory/Yunnan Key Laboratory for Rice Genetic Improvement, Food Crops Research Institute, Yunnan Academy of Agricultural Sciences (YAAS), Kunming, 650200, P. R. China
| | - Jing Li
- Yunnan Seed Laboratory/Yunnan Key Laboratory for Rice Genetic Improvement, Food Crops Research Institute, Yunnan Academy of Agricultural Sciences (YAAS), Kunming, 650200, P. R. China
| | - Haiyuan Chen
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Yanjia Xiao
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Weiwei Chen
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Qiming Wang
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Jiayu Lu
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Keyi Chen
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Chunlei Zhou
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Xin Zhang
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Zhijun Cheng
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Xiuping Guo
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Yulong Ren
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Xiaoming Zheng
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China
| | - Shijia Liu
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Xi Liu
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Yunlu Tian
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Ling Jiang
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China
| | - Dayun Tao
- Yunnan Seed Laboratory/Yunnan Key Laboratory for Rice Genetic Improvement, Food Crops Research Institute, Yunnan Academy of Agricultural Sciences (YAAS), Kunming, 650200, P. R. China.
| | - Chuanyin Wu
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China.
| | - Jianmin Wan
- State Key Laboratory for Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing, 210095, China.
- State Key Laboratory of Crop Gene Resources and Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, 100081, China.
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7
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Unckless RL. Meiotic drive, postzygotic isolation, and the Snowball Effect. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567107. [PMID: 38014228 PMCID: PMC10680770 DOI: 10.1101/2023.11.14.567107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
As populations diverge, they accumulate incompatibilities which reduce gene flow and facilitate the formation of new species. Simple models suggest that the genes that cause Dobzhansky-Muller incompatibilities should accumulate at least as fast as the square of the number of substitutions between taxa, the so-called snowball effect. We show, however, that in the special- but possibly common- case in which hybrid sterility is due primarily to cryptic meiotic (gametic) drive, the number of genes that cause postzygotic isolation may increase nearly linearly with the number of substitutions between species.
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Affiliation(s)
- Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045
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8
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Bobinski M, Pilgrim D. A dominant dpy-10 co-transformation marker using CRISPR/Cas9 and a linear repair template in Caenorhabditis tropicalis. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000900. [PMID: 38021174 PMCID: PMC10656624 DOI: 10.17912/micropub.biology.000900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 09/10/2023] [Accepted: 10/31/2023] [Indexed: 12/01/2023]
Abstract
Caenorhabditis elegans is an excellent genetic model system with a large arsenal of forward and reverse genetic techniques. However, not all approaches are easily ported to related Caenorhabditis species (which are useful for gene conservation and gene pathway evolution studies). For CRISPR/Cas9 genetic editing, an easily screenable and dominant co-transformation marker is required - a secondary mutation that won't impact the phenotype of a desired mutation but is capable of being screened for in heterozygous mutants. We describe here the adaptation of a dominant dumpy/roller CRISPR/Cas9-induced mutation in the C. tropicalis dpy-10 orthologue.
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Affiliation(s)
- Montana Bobinski
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - David Pilgrim
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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9
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Long L, Xu W, Valencia F, Paaby AB, McGrath PT. A toxin-antidote selfish element increases fitness of its host. eLife 2023; 12:e81640. [PMID: 37874324 PMCID: PMC10629817 DOI: 10.7554/elife.81640] [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: 07/05/2022] [Accepted: 10/23/2023] [Indexed: 10/25/2023] Open
Abstract
Selfish genetic elements can promote their transmission at the expense of individual survival, creating conflict between the element and the rest of the genome. Recently, a large number of toxin-antidote (TA) post-segregation distorters have been identified in non-obligate outcrossing nematodes. Their origin and the evolutionary forces that keep them at intermediate population frequencies are poorly understood. Here, we study a TA element in Caenorhabditis elegans called zeel-1;peel-1. Two major haplotypes of this locus, with and without the selfish element, segregate in C. elegans. We evaluate the fitness consequences of the zeel-1;peel-1 element outside of its role in gene drive in non-outcrossing animals and demonstrate that loss of the toxin peel-1 decreased fitness of hermaphrodites and resulted in reductions in fecundity and body size. These findings suggest a biological role for peel-1 beyond toxin lethality. This work demonstrates that a TA element can provide a fitness benefit to its hosts either during their initial evolution or by being co-opted by the animals following their selfish spread. These findings guide our understanding on how TA elements can remain in a population where gene drive is minimized, helping resolve the mystery of prevalent TA elements in selfing animals.
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Affiliation(s)
- Lijiang Long
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
- Interdisciplinary Graduate Program in Quantitative Biosciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Wen Xu
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Francisco Valencia
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Annalise B Paaby
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Patrick T McGrath
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
- School of Physics, Georgia Institute of TechnologyAtlantaUnited States
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10
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Cutter AD. Speciation and development. Evol Dev 2023; 25:289-327. [PMID: 37545126 DOI: 10.1111/ede.12454] [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: 03/07/2023] [Revised: 06/13/2023] [Accepted: 07/20/2023] [Indexed: 08/08/2023]
Abstract
Understanding general principles about the origin of species remains one of the foundational challenges in evolutionary biology. The genomic divergence between groups of individuals can spawn hybrid inviability and hybrid sterility, which presents a tantalizing developmental problem. Divergent developmental programs may yield either conserved or divergent phenotypes relative to ancestral traits, both of which can be responsible for reproductive isolation during the speciation process. The genetic mechanisms of developmental evolution involve cis- and trans-acting gene regulatory change, protein-protein interactions, genetic network structures, dosage, and epigenetic regulation, all of which also have roots in population genetic and molecular evolutionary processes. Toward the goal of demystifying Darwin's "mystery of mysteries," this review integrates microevolutionary concepts of genetic change with principles of organismal development, establishing explicit links between population genetic process and developmental mechanisms in the production of macroevolutionary pattern. This integration aims to establish a more unified view of speciation that binds process and mechanism.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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11
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Widen SA, Bes IC, Koreshova A, Pliota P, Krogull D, Burga A. Virus-like transposons cross the species barrier and drive the evolution of genetic incompatibilities. Science 2023; 380:eade0705. [PMID: 37384706 DOI: 10.1126/science.ade0705] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 05/17/2023] [Indexed: 07/01/2023]
Abstract
Horizontal gene transfer, the movement of genetic material between species, has been reported across all major eukaryotic lineages. However, the underlying mechanisms of transfer and their impact on genome evolution are still poorly understood. While studying the evolutionary origin of a selfish element in the nematode Caenorhabditis briggsae, we discovered that Mavericks, ancient virus-like transposons related to giant viruses and virophages, are one of the long-sought vectors of horizontal gene transfer. We found that Mavericks gained a novel herpesvirus-like fusogen in nematodes, leading to the widespread exchange of cargo genes between extremely divergent species, bypassing sexual and genetic barriers spanning hundreds of millions of years. Our results show how the union between viruses and transposons causes horizontal gene transfer and ultimately genetic incompatibilities in natural populations.
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Affiliation(s)
- Sonya A Widen
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Israel Campo Bes
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Alevtina Koreshova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Pinelopi Pliota
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Daniel Krogull
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Alejandro Burga
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
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12
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Fausett SR, Sandjak A, Billard B, Braendle C. Higher-order epistasis shapes natural variation in germ stem cell niche activity. Nat Commun 2023; 14:2824. [PMID: 37198172 DOI: 10.1038/s41467-023-38527-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 05/05/2023] [Indexed: 05/19/2023] Open
Abstract
To study how natural allelic variation explains quantitative developmental system variation, we characterized natural differences in germ stem cell niche activity, measured as progenitor zone (PZ) size, between two Caenorhabditis elegans isolates. Linkage mapping yielded candidate loci on chromosomes II and V, and we found that the isolate with a smaller PZ size harbours a 148 bp promoter deletion in the Notch ligand, lag-2/Delta, a central signal promoting germ stem cell fate. As predicted, introducing this deletion into the isolate with a large PZ resulted in a smaller PZ size. Unexpectedly, restoring the deleted ancestral sequence in the isolate with a smaller PZ did not increase-but instead further reduced-PZ size. These seemingly contradictory phenotypic effects are explained by epistatic interactions between the lag-2/Delta promoter, the chromosome II locus, and additional background loci. These results provide first insights into the quantitative genetic architecture regulating an animal stem cell system.
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Affiliation(s)
- Sarah R Fausett
- Université Côte d'Azur, CNRS, Inserm, IBV, Nice, France.
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA.
| | - Asma Sandjak
- Université Côte d'Azur, CNRS, Inserm, IBV, Nice, France
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13
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Huang Y, Lo YH, Hsu JC, Le TS, Yang FJ, Chang T, Braendle C, Wang J. Widespread sex ratio polymorphism in Caenorhabditis nematodes. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221636. [PMID: 36938539 PMCID: PMC10014251 DOI: 10.1098/rsos.221636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Although equal sex ratio is ubiquitous and represents an equilibrium in evolutionary theory, biased sex ratios are predicted for certain local conditions. Cases of sex ratio bias have been mostly reported for single species, but little is known about its evolution above the species level. Here, we surveyed progeny sex ratios in 23 species of the nematode genus Caenorhabditis, including 19 for which we tested multiple strains. For the species with multiple strains, five species had female-biased and two had non-biased sex ratios in all strains, respectively. The other 12 species showed polymorphic sex ratios across strains. Female-biased sex ratios could be due to sperm competition whereby X-bearing sperm outcompete nullo-X sperm during fertilization. In this model, when sperm are limited allowing all sperm to be used, sex ratios are expected to be equal. However, in assays limiting mating to a few hours, most strains showed similarly biased sex ratios compared with unlimited mating experiments, except that one C. becei strain showed significantly reduced female bias compared with unlimited mating. Our study shows frequent polymorphism in sex ratios within Caenorhabditis species and that sperm competition alone cannot explain the sex ratio bias.
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Affiliation(s)
- Yun Huang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yun-Hua Lo
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Jung-Chen Hsu
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Tho Son Le
- Department of Molecular Genetics and Gene Technology, College of Forestry Biotechnology, Vietnam National University of Forestry, Hanoi, Vietnam
| | - Fang-Jung Yang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Tiffany Chang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | | | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
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14
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Velazco-Cruz L, Ross JA. Genetic architecture and temporal analysis of Caenorhabditis briggsae hybrid developmental delay. PLoS One 2022; 17:e0272843. [PMID: 35951524 PMCID: PMC9371335 DOI: 10.1371/journal.pone.0272843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/27/2022] [Indexed: 11/18/2022] Open
Abstract
Identifying the alleles that reduce hybrid fitness is a major goal in the study of speciation genetics. It is rare to identify systems in which hybrid incompatibilities with minor phenotypic effects are segregating in genetically diverse populations of the same biological species. Such traits do not themselves cause reproductive isolation but might initiate the process. In the nematode Caenorhabditis briggsae, a small percent of F2 generation hybrids between two natural populations suffer from developmental delay, in which adulthood is reached after approximately 33% more time than their wild-type siblings. Prior efforts to identify the genetic basis for this hybrid incompatibility assessed linkage using one or two genetic markers on chromosome III and suggested that delay is caused by a toxin-antidote element. Here, we have genotyped F2 hybrids using multiple chromosome III markers to refine the developmental delay locus. Also, to better define the developmental delay phenotype, we measured the development rate of 66 F2 hybrids and found that delay is not restricted to a particular larval developmental stage. Deviation of the developmental delay frequency from hypothetical expectations for a toxin-antidote element adds support to the assertion that the epistatic interaction is not fully penetrant. Our mapping and refinement of the delay phenotype motivates future efforts to study the genetic architecture of hybrid dysfunction between genetically distinct populations of one species by identifying the underlying loci.
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Affiliation(s)
- Leonardo Velazco-Cruz
- Department of Biology, California State University, Fresno, California, United States of America
| | - Joseph A. Ross
- Department of Biology, California State University, Fresno, California, United States of America
- * E-mail:
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15
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Tafreshi AG, Otto SP, Chapuisat M. Unbalanced selection: the challenge of maintaining a social polymorphism when a supergene is selfish. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210197. [PMID: 35694754 PMCID: PMC9189496 DOI: 10.1098/rstb.2021.0197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Supergenes often have multiple phenotypic effects, including unexpected detrimental ones, because recombination suppression maintains associations among co-adapted alleles but also allows the accumulation of recessive deleterious mutations and selfish genetic elements. Yet, supergenes often persist over long evolutionary periods. How are such polymorphisms maintained in the face of selection, drive and drift? We present a population genetic model that investigates the conditions necessary for a stable polymorphic equilibrium when one of the supergene haplotypes is a selfish genetic element. The model fits the characteristics of the Alpine silver ant, Formica selysi, in which a large supergene underlies colony social organization, and one haplotype distorts Mendelian transmission by killing progeny that did not inherit it. The model shows that such maternal-effect killing strongly limits the maintenance of social polymorphism. Under random mating, transmission ratio distortion prevents rare single-queen colonies from invading populations of multiple-queen colonies, regardless of the fitness of each genotype. A stable polymorphic equilibrium can, however, be reached when high rates of assortative mating are combined with large fitness differences among supergene genotypes. The model reveals that the persistence of the social polymorphism is non-trivial and expected to occur only under restrictive conditions that deserve further empirical investigation. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Alireza G Tafreshi
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Sarah P Otto
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
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16
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Stevens L, Moya ND, Tanny RE, Gibson SB, Tracey A, Na H, Chitrakar R, Dekker J, Walhout AJ, Baugh LR, Andersen EC. Chromosome-level reference genomes for two strains of Caenorhabditis briggsae: an improved platform for comparative genomics. Genome Biol Evol 2022; 14:6554914. [PMID: 35348662 PMCID: PMC9011032 DOI: 10.1093/gbe/evac042] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
The publication of the Caenorhabditis briggsae reference genome in 2003 enabled the first comparative genomics studies between C. elegans and C. briggsae, shedding light on the evolution of genome content and structure in the Caenorhabditis genus. However, despite being widely used, the currently available C. briggsae reference genome is substantially less complete and structurally accurate than the C. elegans reference genome. Here, we used high-coverage Oxford Nanopore long-read and chromosome conformation capture data to generate chromosome-level reference genomes for two C. briggsae strains: QX1410, a new reference strain closely related to the laboratory AF16 strain, and VX34, a highly divergent strain isolated in China. We also sequenced 99 recombinant inbred lines (RILs) generated from reciprocal crosses between QX1410 and VX34 to create a recombination map and identify chromosomal domains. Additionally, we used both short- and long-read RNA sequencing (RNA-seq) data to generate high-quality gene annotations. By comparing these new reference genomes to the current reference, we reveal that hyper-divergent haplotypes cover large portions of the C. briggsae genome, similar to recent reports in C. elegans and C. tropicalis. We also show that the genomes of selfing Caenorhabditis species have undergone more rearrangement than their outcrossing relatives, which has biased previous estimates of rearrangement rate in Caenorhabditis. These new genomes provide a substantially improved platform for comparative genomics in Caenorhabditis and narrow the gap between the quality of genomic resources available for C. elegans and C. briggsae.
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Affiliation(s)
- Lewis Stevens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Nicolas D. Moya
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA
| | - Robyn E. Tanny
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Sophia B. Gibson
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Alan Tracey
- Tree of Life, Wellcome Sanger Institute, Cambridge, UK
| | - Huimin Na
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | | | - Job Dekker
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Albertha J.M. Walhout
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - L. Ryan Baugh
- Department of Biology, Duke University, Durham, NC, USA
- Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | - Erik C. Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
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17
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Adams PE, Crist AB, Young EM, Willis JH, Phillips PC, Fierst JL. Slow Recovery from Inbreeding Depression Generated by the Complex Genetic Architecture of Segregating Deleterious Mutations. Mol Biol Evol 2022; 39:msab330. [PMID: 34791426 PMCID: PMC8789292 DOI: 10.1093/molbev/msab330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The deleterious effects of inbreeding have been of extreme importance to evolutionary biology, but it has been difficult to characterize the complex interactions between genetic constraints and selection that lead to fitness loss and recovery after inbreeding. Haploid organisms and selfing organisms like the nematode Caenorhabditis elegans are capable of rapid recovery from the fixation of novel deleterious mutation; however, the potential for recovery and genomic consequences of inbreeding in diploid, outcrossing organisms are not well understood. We sought to answer two questions: 1) Can a diploid, outcrossing population recover from inbreeding via standing genetic variation and new mutation? and 2) How does allelic diversity change during recovery? We inbred C. remanei, an outcrossing relative of C. elegans, through brother-sister mating for 30 generations followed by recovery at large population size. Inbreeding reduced fitness but, surprisingly, recovery from inbreeding at large populations sizes generated only very moderate fitness recovery after 300 generations. We found that 65% of ancestral single nucleotide polymorphisms (SNPs) were fixed in the inbred population, far fewer than the theoretical expectation of ∼99%. Under recovery, 36 SNPs across 30 genes involved in alimentary, muscular, nervous, and reproductive systems changed reproducibly across replicates, indicating that strong selection for fitness recovery does exist. Our results indicate that recovery from inbreeding depression via standing genetic variation and mutation is likely to be constrained by the large number of segregating deleterious variants present in natural populations, limiting the capacity for recovery of small populations.
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Affiliation(s)
- Paula E Adams
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Anna B Crist
- Department of Genomes and Genetics, Institut Pasteur, Paris, France
| | - Ellen M Young
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - John H Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Janna L Fierst
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
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18
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Andersen EC, Rockman MV. Natural genetic variation as a tool for discovery in Caenorhabditis nematodes. Genetics 2022; 220:iyab156. [PMID: 35134197 PMCID: PMC8733454 DOI: 10.1093/genetics/iyab156] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 09/11/2021] [Indexed: 11/12/2022] Open
Abstract
Over the last 20 years, studies of Caenorhabditis elegans natural diversity have demonstrated the power of quantitative genetic approaches to reveal the evolutionary, ecological, and genetic factors that shape traits. These studies complement the use of the laboratory-adapted strain N2 and enable additional discoveries not possible using only one genetic background. In this chapter, we describe how to perform quantitative genetic studies in Caenorhabditis, with an emphasis on C. elegans. These approaches use correlations between genotype and phenotype across populations of genetically diverse individuals to discover the genetic causes of phenotypic variation. We present methods that use linkage, near-isogenic lines, association, and bulk-segregant mapping, and we describe the advantages and disadvantages of each approach. The power of C. elegans quantitative genetic mapping is best shown in the ability to connect phenotypic differences to specific genes and variants. We will present methods to narrow genomic regions to candidate genes and then tests to identify the gene or variant involved in a quantitative trait. The same features that make C. elegans a preeminent experimental model animal contribute to its exceptional value as a tool to understand natural phenotypic variation.
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Affiliation(s)
- Erik C Andersen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60201, USA
| | - Matthew V Rockman
- Department of Biology and Center for Genomics & Systems Biology, New York University, New York, NY 10003, USA
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19
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Félix MA. Evolution: Drivers in a Traffic Jam. Curr Biol 2021; 31:R257-R260. [PMID: 33689727 DOI: 10.1016/j.cub.2021.01.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Genetic loci coding for a toxin and its antidote behave like selfish elements. Two new studies find an accumulation of such elements in one species.
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Affiliation(s)
- Marie-Anne Félix
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS, Inserm, Paris, France.
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20
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Noble LM, Yuen J, Stevens L, Moya N, Persaud R, Moscatelli M, Jackson JL, Zhang G, Chitrakar R, Baugh LR, Braendle C, Andersen EC, Seidel HS, Rockman MV. Selfing is the safest sex for Caenorhabditis tropicalis. eLife 2021; 10:e62587. [PMID: 33427200 PMCID: PMC7853720 DOI: 10.7554/elife.62587] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 12/30/2022] Open
Abstract
Mating systems have profound effects on genetic diversity and compatibility. The convergent evolution of self-fertilization in three Caenorhabditis species provides a powerful lens to examine causes and consequences of mating system transitions. Among the selfers, Caenorhabditis tropicalis is the least genetically diverse and most afflicted by outbreeding depression. We generated a chromosomal-scale genome for C. tropicalis and surveyed global diversity. Population structure is very strong, and islands of extreme divergence punctuate a genomic background that is highly homogeneous around the globe. Outbreeding depression in the laboratory is caused largely by multiple Medea-like elements, genetically consistent with maternal toxin/zygotic antidote systems. Loci with Medea activity harbor novel and duplicated genes, and their activity is modified by mito-nuclear background. Segregating Medea elements dramatically reduce fitness, and simulations show that selfing limits their spread. Frequent selfing in C. tropicalis may therefore be a strategy to avoid Medea-mediated outbreeding depression.
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Affiliation(s)
- Luke M Noble
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
- Institute de Biologie, École Normale Supérieure, CNRS, InsermParisFrance
| | - John Yuen
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | - Lewis Stevens
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Nicolas Moya
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Riaad Persaud
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | - Marc Moscatelli
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | - Jacqueline L Jackson
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | - Gaotian Zhang
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | | | - L Ryan Baugh
- Department of Biology, Duke UniversityDurhamUnited States
| | - Christian Braendle
- Institut de Biologie Valrose, Université Côte d’Azur, CNRS, InsermNiceFrance
| | - Erik C Andersen
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Hannah S Seidel
- Department of Biology, Eastern Michigan UniversityYpsilantiUnited States
| | - Matthew V Rockman
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
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