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Laetsch DR, Bisschop G, Martin SH, Aeschbacher S, Setter D, Lohse K. Demographically explicit scans for barriers to gene flow using gIMble. PLoS Genet 2023; 19:e1010999. [PMID: 37816069 PMCID: PMC10610087 DOI: 10.1371/journal.pgen.1010999] [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: 06/06/2023] [Revised: 10/27/2023] [Accepted: 09/25/2023] [Indexed: 10/12/2023] Open
Abstract
Identifying regions of the genome that act as barriers to gene flow between recently diverged taxa has remained challenging given the many evolutionary forces that generate variation in genetic diversity and divergence along the genome, and the stochastic nature of this variation. Progress has been impeded by a conceptual and methodological divide between analyses that infer the demographic history of speciation and genome scans aimed at identifying locally maladaptive alleles i.e. genomic barriers to gene flow. Here we implement genomewide IM blockwise likelihood estimation (gIMble), a composite likelihood approach for the quantification of barriers, that bridges this divide. This analytic framework captures background selection and selection against barriers in a model of isolation with migration (IM) as heterogeneity in effective population size (Ne) and effective migration rate (me), respectively. Variation in both effective demographic parameters is estimated in sliding windows via pre-computed likelihood grids. gIMble includes modules for pre-processing/filtering of genomic data and performing parametric bootstraps using coalescent simulations. To demonstrate the new approach, we analyse data from a well-studied pair of sister species of tropical butterflies with a known history of post-divergence gene flow: Heliconius melpomene and H. cydno. Our analyses uncover both large-effect barrier loci (including well-known wing-pattern genes) and a genome-wide signal of a polygenic barrier architecture.
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Affiliation(s)
- Dominik R. Laetsch
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Gertjan Bisschop
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Simon H. Martin
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Simon Aeschbacher
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Derek Setter
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Konrad Lohse
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, United Kingdom
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Hanly JJ, Loh LS, Mazo-Vargas A, Rivera-Miranda TS, Livraghi L, Tendolkar A, Day CR, Liutikaite N, Earls EA, Corning OBWH, D'Souza N, Hermina-Perez JJ, Mehta C, Ainsworth JA, Rossi M, Papa R, McMillan WO, Perry MW, Martin A. Frizzled2 receives WntA signaling during butterfly wing pattern formation. Development 2023; 150:dev201868. [PMID: 37602496 PMCID: PMC10560568 DOI: 10.1242/dev.201868] [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: 04/12/2023] [Accepted: 08/04/2023] [Indexed: 08/22/2023]
Abstract
Butterfly color patterns provide visible and biodiverse phenotypic readouts of the patterning processes. Although the secreted ligand WntA has been shown to instruct the color pattern formation in butterflies, its mode of reception remains elusive. Butterfly genomes encode four homologs of the Frizzled-family of Wnt receptors. Here, we show that CRISPR mosaic knockouts of frizzled2 (fz2) phenocopy the color pattern effects of WntA loss of function in multiple nymphalids. Whereas WntA mosaic clones result in intermediate patterns of reduced size, fz2 clones are cell-autonomous, consistent with a morphogen function. Shifts in expression of WntA and fz2 in WntA crispant pupae show that they are under positive and negative feedback, respectively. Fz1 is required for Wnt-independent planar cell polarity in the wing epithelium. Fz3 and Fz4 show phenotypes consistent with Wnt competitive-antagonist functions in vein formation (Fz3 and Fz4), wing margin specification (Fz3), and color patterning in the Discalis and Marginal Band Systems (Fz4). Overall, these data show that the WntA/Frizzled2 morphogen-receptor pair forms a signaling axis that instructs butterfly color patterning and shed light on the functional diversity of insect Frizzled receptors.
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Affiliation(s)
- Joseph J. Hanly
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
- Smithsonian Tropical Research Institute, Gamboa 0843-03092, Panama
| | - Ling S. Loh
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Anyi Mazo-Vargas
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | | | - Luca Livraghi
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
- Smithsonian Tropical Research Institute, Gamboa 0843-03092, Panama
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Amruta Tendolkar
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Christopher R. Day
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Durham, NC 27708, USA
| | - Neringa Liutikaite
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Emily A. Earls
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Olaf B. W. H. Corning
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Natalie D'Souza
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - José J. Hermina-Perez
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Caroline Mehta
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Julia A. Ainsworth
- Department of Cell and Developmental Biology, UC San Diego, La Jolla, CA, USA
| | - Matteo Rossi
- Division of Evolutionary Biology, Ludwig Maximilian University, Munich 80539, Germany
| | - Riccardo Papa
- Department of Biology, University of Puerto Rico at Río Piedras, San Juan 00931, Puerto Rico
- Molecular Sciences and Research Center, University of Puerto Rico, San Juan 00931, Puerto Rico
- Dipartimento di Scienze Chimiche della Vita e della Sostenibilità Ambientale, Università di Parma, Parma 43121, Italy
| | - W. Owen McMillan
- Smithsonian Tropical Research Institute, Gamboa 0843-03092, Panama
| | - Michael W. Perry
- Department of Cell and Developmental Biology, UC San Diego, La Jolla, CA, USA
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
- Smithsonian Tropical Research Institute, Gamboa 0843-03092, Panama
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Thulluru A, Saad L, Nagah Abdou Y, Martin A, Kee HL. CRISPR in butterflies: An undergraduate lab experience to inactivate wing patterning genes during development. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 50:605-619. [PMID: 36054482 DOI: 10.1002/bmb.21669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 06/13/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
CRISPR is a technique increasingly used in the laboratory for both fundamental and applied research. We designed and implemented a lab experience for undergraduates to carry out CRISPR technology in the lab, and knockout the wing patterning genes optix and WntA in Vanessa cardui butterflies. Students obtained spectacular phenotypic mutants of butterfly wings color and patterns, awakening curiosity about how genomes encode morphology. In addition, students successfully used molecular techniques to genotype and screen wild-type caterpillar larvae and butterflies for CRISPR edits in genes. Student feedback suggests that they experienced a meaningful process of scientific inquiry by carrying out the whole CRISPR workflow process, from the design and delivery of CRISPR components through microinjection of butterfly eggs, the rearing of live animals through their complete life cycle, and molecular and phenotypic analyses of the resulting mutants. We discuss our experience using CRISP genome editing experiments in butterflies to expose students to hands-on research experiences probing gene-to-phenotype relationships in a charismatic and live organism.
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Affiliation(s)
- Aamani Thulluru
- Department of Biology, Stetson University, DeLand, Florida, USA
| | - Luisa Saad
- Department of Biology, Stetson University, DeLand, Florida, USA
| | | | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia, USA
| | - Hooi Lynn Kee
- Department of Biology, Stetson University, DeLand, Florida, USA
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