1
|
Maier PA, Vandergast AG, Bohonak AJ. Yosemite toad (Anaxyrus canorus) transcriptome reveals interplay between speciation genes and adaptive introgression. Mol Ecol 2024; 33:e17317. [PMID: 38488670 DOI: 10.1111/mec.17317] [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: 05/11/2023] [Revised: 02/15/2024] [Accepted: 02/23/2024] [Indexed: 04/09/2024]
Abstract
Genomes are heterogeneous during the early stages of speciation, with small 'islands' of DNA appearing to reflect strong adaptive differences, surrounded by vast seas of relative homogeneity. As species diverge, secondary contact zones between them can act as an interface and selectively filter through advantageous alleles of hybrid origin. Such introgression is another important adaptive process, one that allows beneficial mosaics of recombinant DNA ('rivers') to flow from one species into another. Although genomic islands of divergence appear to be associated with reproductive isolation, and genomic rivers form by adaptive introgression, it is unknown whether islands and rivers tend to be the same or different loci. We examined three replicate secondary contact zones for the Yosemite toad (Anaxyrus canorus) using two genomic data sets and a morphometric data set to answer the questions: (1) How predictably different are islands and rivers, both in terms of genomic location and gene function? (2) Are the adaptive genetic trait loci underlying tadpole growth and development reliably islands, rivers or neither? We found that island and river loci have significant overlap within a contact zone, suggesting that some loci are first islands, and later are predictably converted into rivers. However, gene ontology enrichment analysis showed strong overlap in gene function unique to all island loci, suggesting predictability in overall gene pathways for islands. Genome-wide association study outliers for tadpole development included LPIN3, a lipid metabolism gene potentially involved in climate change adaptation, that is island-like for all three contact zones, but also appears to be introgressing (as a river) across one zone. Taken together, our results suggest that adaptive divergence and introgression may be more complementary forces than currently appreciated.
Collapse
Affiliation(s)
- Paul A Maier
- Department of Biology, San Diego State University, San Diego, California, USA
- Family TreeDNA, Gene by Gene, Houston, Texas, USA
| | - Amy G Vandergast
- Western Ecological Research Center, San Diego Field Station, U.S. Geological Survey, San Diego, California, USA
| | - Andrew J Bohonak
- Department of Biology, San Diego State University, San Diego, California, USA
| |
Collapse
|
2
|
Bohutínská M, Peichel CL. Divergence time shapes gene reuse during repeated adaptation. Trends Ecol Evol 2024; 39:396-407. [PMID: 38155043 DOI: 10.1016/j.tree.2023.11.007] [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: 08/10/2023] [Revised: 11/15/2023] [Accepted: 11/20/2023] [Indexed: 12/30/2023]
Abstract
When diverse lineages repeatedly adapt to similar environmental challenges, the extent to which the same genes are involved (gene reuse) varies across systems. We propose that divergence time among lineages is a key factor driving this variability: as lineages diverge, the extent of gene reuse should decrease due to reductions in allele sharing, functional differentiation among genes, and restructuring of genome architecture. Indeed, we show that many genomic studies of repeated adaptation find that more recently diverged lineages exhibit higher gene reuse during repeated adaptation, but the relationship becomes less clear at older divergence time scales. Thus, future research should explore the factors shaping gene reuse and their interplay across broad divergence time scales for a deeper understanding of evolutionary repeatability.
Collapse
Affiliation(s)
- Magdalena Bohutínská
- Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, Bern, 3012, Switzerland; Department of Botany, Faculty of Science, Charles University, Prague, 12800, Czech Republic.
| | - Catherine L Peichel
- Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, Bern, 3012, Switzerland
| |
Collapse
|
3
|
Rödelsperger C. Comparative Genomics of Sex, Chromosomes, and Sex Chromosomes in Caenorhabditis elegans and Other Nematodes. Methods Mol Biol 2024; 2802:455-472. [PMID: 38819568 DOI: 10.1007/978-1-0716-3838-5_15] [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] [Indexed: 06/01/2024]
Abstract
The nematode phylum has evolved a remarkable diversity of reproductive modes, including the repeated emergence of asexuality and hermaphroditism across divergent clades. The species-richness and small genome size of nematodes make them ideal systems for investigating the genome-wide causes and consequences of such major transitions. The availability of functional annotations for most Caenorhabditis elegans genes further allows the linking of patterns of gene content evolution with biological processes. Such gene-centric studies were recently complemented by investigations of chromosome evolution that made use of the first chromosome-scale genome assemblies outside the Caenorhabditis genus. This review highlights recent comparative genomic studies of reproductive mode evolution addressing the hybrid origin of asexuality and the parallel gene loss following the emergence of hermaphroditism. It further summarizes ongoing efforts to characterize ancient linkage blocks called Nigon elements, which form central units of chromosome evolution. Fusions between Nigon elements have been demonstrated to impact recombination and speciation. Finally, multiple recent fusions between autosomal and the sex-linked Nigon element reveal insights into the dynamic evolution of sex chromosomes across various timescales.
Collapse
Affiliation(s)
- Christian Rödelsperger
- Department for Integrative Evolutionary Biology, Max Planck Institute for Biology, Tübingen, Germany.
| |
Collapse
|
4
|
Ivanova M, Moss EG. Orthologs of the Caenorhabditis elegans heterochronic genes have divergent functions in Caenorhabditis briggsae. Genetics 2023; 225:iyad177. [PMID: 37788363 PMCID: PMC10697817 DOI: 10.1093/genetics/iyad177] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 05/22/2023] [Accepted: 09/14/2023] [Indexed: 10/05/2023] Open
Abstract
The heterochronic genes of Caenorhabditis elegans comprise the best-studied pathway controlling the timing of tissue and organ formation in an animal. To begin to understand the evolution of this pathway and the significance of the relationships among its components, we characterized 11 Caenorhabditis briggsae orthologs of C. elegans heterochronic genes. Using CRISPR/Cas9, we made a variety of alleles and found that several mutant phenotypes differ in significant ways from those of C. elegans. Although most mutant orthologs displayed defects in developmental timing, their phenotypes could differ in which stages were affected, the penetrance and expressivity of the phenotypes, or by having additional pleiotropies that were not obviously connected to developmental timing. However, when examining pairwise epistasis and synergistic relationships, we found those paralleled the known relationships between their C. elegans orthologs, suggesting that the arrangements of these genes in functional modules are conserved, but the modules' relationships to each other and/or to their targets has drifted since the time of the species' last common ancestor. Furthermore, our investigation has revealed a relationship between this pathway to other aspects of the animal's growth and development, including gonad development, which is relevant to both species.
Collapse
Affiliation(s)
- Maria Ivanova
- Department of Molecular Biology, Rowan-Virtua School of Translational Biomedical Engineering and Sciences, Rowan University, Stratford, NJ 08084, USA
| | - Eric G Moss
- Department of Molecular Biology, Rowan University, Stratford, NJ 08084, USA
| |
Collapse
|
5
|
Woodruff GC, Willis JH, Johnson E, Phillips PC. Widespread changes in gene expression accompany body size evolution in nematodes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.30.564729. [PMID: 37961435 PMCID: PMC10635002 DOI: 10.1101/2023.10.30.564729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Body size is a fundamental trait that drives multiple evolutionary and ecological patterns. Caenorhabditis inopinata is a fig-associated nematode that is exceptionally large relative to other members of the genus, including C. elegans. We previously showed that C. inopinata is large primarily due to postembryonic cell size expansion that occurs during the larval-to-adult transition. Here, we describe gene expression patterns in C. elegans and C. inopinata throughout this developmental period to understand the transcriptional basis of body size change. We performed RNA-seq in both species across the L3, L4, and adult stages. Most genes are differentially expressed across all developmental stages, consistent with C. inopinata's divergent ecology and morphology. We also used a model comparison approach to identify orthologs with divergent dynamics across this developmental period between the two species. This included genes connected to neurons, behavior, stress response, developmental timing, and small RNA/chromatin regulation. Multiple hypodermal collagens were also observed to harbor divergent developmental dynamics across this period, and genes important for molting and body morphology were also detected. Genes associated with TGF-β signaling revealed idiosyncratic and unexpected transcriptional patterns given their role in body size regulation in C. elegans. Widespread transcriptional divergence between these species is unexpected and may be a signature of the ecological and morphological divergence of C. inopinata. Alternatively, transcriptional turnover may be the rule in the Caenorhabditis genus, indicative of widespread developmental system drift among species. This work lays the foundation for future functional genetic studies interrogating the bases of body size evolution in this group.
Collapse
Affiliation(s)
- Gavin C Woodruff
- University of Oregon, Eugene, Oregon, USA
- Current institution: University of Oklahoma, Norman, Oklahoma, USA
| | | | | | | |
Collapse
|
6
|
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.
Collapse
Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
7
|
Functional genomic tools for emerging model species. Trends Ecol Evol 2022; 37:1104-1115. [PMID: 35914975 DOI: 10.1016/j.tree.2022.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 01/12/2023]
Abstract
Most studies in the field of ecology and evolution aiming to connect genotype to phenotype rarely validate identified loci using functional tools. Recent developments in RNA interference (RNAi) and clustered regularly interspaced palindromic repeats (CRISPR)-Cas genome editing have dramatically increased the feasibility of functional validation. However, these methods come with specific challenges when applied to emerging model organisms, including limited spatial control of gene silencing, low knock-in efficiencies, and low throughput of functional validation. Moreover, many functional studies to date do not recapitulate ecologically relevant variation, and this limits their scope for deeper insights into evolutionary processes. We therefore argue that increased use of gene editing by allelic replacement through homology-directed repair (HDR) would greatly benefit the field of ecology and evolution.
Collapse
|
8
|
Campos TL, Korhonen PK, Hofmann A, Gasser RB, Young ND. Harnessing model organism genomics to underpin the machine learning-based prediction of essential genes in eukaryotes - Biotechnological implications. Biotechnol Adv 2021; 54:107822. [PMID: 34461202 DOI: 10.1016/j.biotechadv.2021.107822] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/17/2021] [Accepted: 08/24/2021] [Indexed: 12/17/2022]
Abstract
The availability of high-quality genomes and advances in functional genomics have enabled large-scale studies of essential genes in model eukaryotes, including the 'elegant worm' (Caenorhabditis elegans; Nematoda) and the 'vinegar fly' (Drosophila melanogaster; Arthropoda). However, this is not the case for other, much less-studied organisms, such as socioeconomically important parasites, for which functional genomic platforms usually do not exist. Thus, there is a need to develop innovative techniques or approaches for the prediction, identification and investigation of essential genes. A key approach that could enable the prediction of such genes is machine learning (ML). Here, we undertake an historical review of experimental and computational approaches employed for the characterisation of essential genes in eukaryotes, with a particular focus on model ecdysozoans (C. elegans and D. melanogaster), and discuss the possible applicability of ML-approaches to organisms such as socioeconomically important parasites. We highlight some recent results showing that high-performance ML, combined with feature engineering, allows a reliable prediction of essential genes from extensive, publicly available 'omic data sets, with major potential to prioritise such genes (with statistical confidence) for subsequent functional genomic validation. These findings could 'open the door' to fundamental and applied research areas. Evidence of some commonality in the essential gene-complement between these two organisms indicates that an ML-engineering approach could find broader applicability to ecdysozoans such as parasitic nematodes or arthropods, provided that suitably large and informative data sets become/are available for proper feature engineering, and for the robust training and validation of algorithms. This area warrants detailed exploration to, for example, facilitate the identification and characterisation of essential molecules as novel targets for drugs and vaccines against parasitic diseases. This focus is particularly important, given the substantial impact that such diseases have worldwide, and the current challenges associated with their prevention and control and with drug resistance in parasite populations.
Collapse
Affiliation(s)
- Tulio L Campos
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia; Bioinformatics Core Facility, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz (IAM-Fiocruz), Recife, Pernambuco, Brazil
| | - Pasi K Korhonen
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andreas Hofmann
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Neil D Young
- Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia.
| |
Collapse
|
9
|
Manrubia S, Cuesta JA, Aguirre J, Ahnert SE, Altenberg L, Cano AV, Catalán P, Diaz-Uriarte R, Elena SF, García-Martín JA, Hogeweg P, Khatri BS, Krug J, Louis AA, Martin NS, Payne JL, Tarnowski MJ, Weiß M. From genotypes to organisms: State-of-the-art and perspectives of a cornerstone in evolutionary dynamics. Phys Life Rev 2021; 38:55-106. [PMID: 34088608 DOI: 10.1016/j.plrev.2021.03.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/01/2021] [Indexed: 12/21/2022]
Abstract
Understanding how genotypes map onto phenotypes, fitness, and eventually organisms is arguably the next major missing piece in a fully predictive theory of evolution. We refer to this generally as the problem of the genotype-phenotype map. Though we are still far from achieving a complete picture of these relationships, our current understanding of simpler questions, such as the structure induced in the space of genotypes by sequences mapped to molecular structures, has revealed important facts that deeply affect the dynamical description of evolutionary processes. Empirical evidence supporting the fundamental relevance of features such as phenotypic bias is mounting as well, while the synthesis of conceptual and experimental progress leads to questioning current assumptions on the nature of evolutionary dynamics-cancer progression models or synthetic biology approaches being notable examples. This work delves with a critical and constructive attitude into our current knowledge of how genotypes map onto molecular phenotypes and organismal functions, and discusses theoretical and empirical avenues to broaden and improve this comprehension. As a final goal, this community should aim at deriving an updated picture of evolutionary processes soundly relying on the structural properties of genotype spaces, as revealed by modern techniques of molecular and functional analysis.
Collapse
Affiliation(s)
- Susanna Manrubia
- Department of Systems Biology, Centro Nacional de Biotecnología (CSIC), Madrid, Spain; Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain.
| | - José A Cuesta
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain; Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain; Instituto de Biocomputación y Física de Sistemas Complejos (BiFi), Universidad de Zaragoza, Spain; UC3M-Santander Big Data Institute (IBiDat), Getafe, Madrid, Spain
| | - Jacobo Aguirre
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain; Centro de Astrobiología, CSIC-INTA, ctra. de Ajalvir km 4, 28850 Torrejón de Ardoz, Madrid, Spain
| | - Sebastian E Ahnert
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK; The Alan Turing Institute, British Library, 96 Euston Road, London NW1 2DB, UK
| | | | - Alejandro V Cano
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Pablo Catalán
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain; Departamento de Matemáticas, Universidad Carlos III de Madrid, Leganés, Spain
| | - Ramon Diaz-Uriarte
- Department of Biochemistry, Universidad Autónoma de Madrid, Madrid, Spain; Instituto de Investigaciones Biomédicas "Alberto Sols" (UAM-CSIC), Madrid, Spain
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas, I(2)SysBio (CSIC-UV), València, Spain; The Santa Fe Institute, Santa Fe, NM, USA
| | | | - Paulien Hogeweg
- Theoretical Biology and Bioinformatics Group, Utrecht University, the Netherlands
| | - Bhavin S Khatri
- The Francis Crick Institute, London, UK; Department of Life Sciences, Imperial College London, London, UK
| | - Joachim Krug
- Institute for Biological Physics, University of Cologne, Köln, Germany
| | - Ard A Louis
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford, UK
| | - Nora S Martin
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK; Sainsbury Laboratory, University of Cambridge, Cambridge, UK
| | - Joshua L Payne
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Marcel Weiß
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK; Sainsbury Laboratory, University of Cambridge, Cambridge, UK
| |
Collapse
|
10
|
Sánchez-Ramírez S, Weiss JG, Thomas CG, Cutter AD. Widespread misregulation of inter-species hybrid transcriptomes due to sex-specific and sex-chromosome regulatory evolution. PLoS Genet 2021; 17:e1009409. [PMID: 33667233 PMCID: PMC7968742 DOI: 10.1371/journal.pgen.1009409] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 03/17/2021] [Accepted: 02/09/2021] [Indexed: 01/04/2023] Open
Abstract
When gene regulatory networks diverge between species, their dysfunctional expression in inter-species hybrid individuals can create genetic incompatibilities that generate the developmental defects responsible for intrinsic post-zygotic reproductive isolation. Both cis- and trans-acting regulatory divergence can be hastened by directional selection through adaptation, sexual selection, and inter-sexual conflict, in addition to cryptic evolution under stabilizing selection. Dysfunctional sex-biased gene expression, in particular, may provide an important source of sexually-dimorphic genetic incompatibilities. Here, we characterize and compare male and female/hermaphrodite transcriptome profiles for sibling nematode species Caenorhabditis briggsae and C. nigoni, along with allele-specific expression in their F1 hybrids, to deconvolve features of expression divergence and regulatory dysfunction. Despite evidence of widespread stabilizing selection on gene expression, misexpression of sex-biased genes pervades F1 hybrids of both sexes. This finding implicates greater fragility of male genetic networks to produce dysfunctional organismal phenotypes. Spermatogenesis genes are especially prone to high divergence in both expression and coding sequences, consistent with a "faster male" model for Haldane's rule and elevated sterility of hybrid males. Moreover, underdominant expression pervades male-biased genes compared to female-biased and sex-neutral genes and an excess of cis-trans compensatory regulatory divergence for X-linked genes underscores a "large-X effect" for hybrid male expression dysfunction. Extensive regulatory divergence in sex determination pathway genes likely contributes to demasculinization of XX hybrids. The evolution of genetic incompatibilities due to regulatory versus coding sequence divergence, however, are expected to arise in an uncorrelated fashion. This study identifies important differences between the sexes in how regulatory networks diverge to contribute to sex-biases in how genetic incompatibilities manifest during the speciation process.
Collapse
Affiliation(s)
- Santiago Sánchez-Ramírez
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- * E-mail: (SSR); (ADC)
| | - Jörg G. Weiss
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Cristel G. Thomas
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Asher D. Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- * E-mail: (SSR); (ADC)
| |
Collapse
|
11
|
Coulcher JF, Roure A, Chowdhury R, Robert M, Lescat L, Bouin A, Carvajal Cadavid J, Nishida H, Darras S. Conservation of peripheral nervous system formation mechanisms in divergent ascidian embryos. eLife 2020; 9:e59157. [PMID: 33191918 PMCID: PMC7710358 DOI: 10.7554/elife.59157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/13/2020] [Indexed: 01/23/2023] Open
Abstract
Ascidians with very similar embryos but highly divergent genomes are thought to have undergone extensive developmental system drift. We compared, in four species (Ciona and Phallusia for Phlebobranchia, Molgula and Halocynthia for Stolidobranchia), gene expression and gene regulation for a network of six transcription factors regulating peripheral nervous system (PNS) formation in Ciona. All genes, but one in Molgula, were expressed in the PNS with some differences correlating with phylogenetic distance. Cross-species transgenesis indicated strong levels of conservation, except in Molgula, in gene regulation despite lack of sequence conservation of the enhancers. Developmental system drift in ascidians is thus higher for gene regulation than for gene expression and is impacted not only by phylogenetic distance, but also in a clade-specific manner and unevenly within a network. Finally, considering that Molgula is divergent in our analyses, this suggests deep conservation of developmental mechanisms in ascidians after 390 My of separate evolution.
Collapse
Affiliation(s)
- Joshua F Coulcher
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Agnès Roure
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Rafath Chowdhury
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Méryl Robert
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Laury Lescat
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Aurélie Bouin
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Juliana Carvajal Cadavid
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka UniversityToyonakaJapan
| | - Sébastien Darras
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM)Banyuls-sur-MerFrance
| |
Collapse
|
12
|
Satokangas I, Martin SH, Helanterä H, Saramäki J, Kulmuni J. Multi-locus interactions and the build-up of reproductive isolation. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190543. [PMID: 32654649 PMCID: PMC7423273 DOI: 10.1098/rstb.2019.0543] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2020] [Indexed: 12/15/2022] Open
Abstract
All genes interact with other genes, and their additive effects and epistatic interactions affect an organism's phenotype and fitness. Recent theoretical and empirical work has advanced our understanding of the role of multi-locus interactions in speciation. However, relating different models to one another and to empirical observations is challenging. This review focuses on multi-locus interactions that lead to reproductive isolation (RI) through reduced hybrid fitness. We first review theoretical approaches and show how recent work incorporating a mechanistic understanding of multi-locus interactions recapitulates earlier models, but also makes novel predictions concerning the build-up of RI. These include high variance in the build-up rate of RI among taxa, the emergence of strong incompatibilities producing localized barriers to introgression, and an effect of population size on the build-up of RI. We then review recent experimental approaches to detect multi-locus interactions underlying RI using genomic data. We argue that future studies would benefit from overlapping methods like ancestry disequilibrium scans, genome scans of differentiation and analyses of hybrid gene expression. Finally, we highlight a need for further overlap between theoretical and empirical work, and approaches that predict what kind of patterns multi-locus interactions resulting in incompatibilities will leave in genome-wide polymorphism data. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
Collapse
Affiliation(s)
- I. Satokangas
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1, PO Box 65, 00014 Helsinki, Finland
| | - S. H. Martin
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh EH9 3FL, UK
| | - H. Helanterä
- Ecology and Genetics research unit, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - J. Saramäki
- Department of Computer Science, Aalto University, PO Box 11000, 00076 Aalto, Espoo, Finland
| | - J. Kulmuni
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1, PO Box 65, 00014 Helsinki, Finland
- Tvärminne Zoological Station, University of Helsinki, J. A. Palménin tie 260, 10900 Hanko, Finland
| |
Collapse
|
13
|
Barrière A, Bertrand V. Neuronal specification in C. elegans: combining lineage inheritance with intercellular signaling. J Neurogenet 2020; 34:273-281. [PMID: 32603241 DOI: 10.1080/01677063.2020.1781850] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The nervous system is composed of a high diversity of neuronal types. How this diversity is generated during development is a key question in neurobiology. Addressing this question is one of the reasons that led Sydney Brenner to develop the nematode C. elegans as a model organism. While there was initially a debate on whether the neuronal specification follows a 'European' model (determined by ancestry) or an 'American' model (determined by intercellular communication), several decades of research have established that the truth lies somewhere in between. Neurons are specified by the combination of transcription factors inherited from the ancestor cells and signaling between neighboring cells (especially Wnt and Notch signaling). This converges to the activation in newly generated postmitotic neurons of a specific set of terminal selector transcription factors that initiate and maintain the differentiation of the neuron. In this review, we also discuss the evolution of these specification mechanisms in other nematodes and beyond.
Collapse
Affiliation(s)
- Antoine Barrière
- Aix Marseille University, CNRS, IBDM, Turing Center for Living Systems, Marseille, France
| | - Vincent Bertrand
- Aix Marseille University, CNRS, IBDM, Turing Center for Living Systems, Marseille, France
| |
Collapse
|
14
|
Ewe CK, Torres Cleuren YN, Rothman JH. Evolution and Developmental System Drift in the Endoderm Gene Regulatory Network of Caenorhabditis and Other Nematodes. Front Cell Dev Biol 2020; 8:170. [PMID: 32258041 PMCID: PMC7093329 DOI: 10.3389/fcell.2020.00170] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/02/2020] [Indexed: 01/17/2023] Open
Abstract
Developmental gene regulatory networks (GRNs) underpin metazoan embryogenesis and have undergone substantial modification to generate the tremendous variety of animal forms present on Earth today. The nematode Caenorhabditis elegans has been a central model for advancing many important discoveries in fundamental mechanistic biology and, more recently, has provided a strong base from which to explore the evolutionary diversification of GRN architecture and developmental processes in other species. In this short review, we will focus on evolutionary diversification of the GRN for the most ancient of the embryonic germ layers, the endoderm. Early embryogenesis diverges considerably across the phylum Nematoda. Notably, while some species deploy regulative development, more derived species, such as C. elegans, exhibit largely mosaic modes of embryogenesis. Despite the relatively similar morphology of the nematode gut across species, widespread variation has been observed in the signaling inputs that initiate the endoderm GRN, an exemplar of developmental system drift (DSD). We will explore how genetic variation in the endoderm GRN helps to drive DSD at both inter- and intraspecies levels, thereby resulting in a robust developmental system. Comparative studies using divergent nematodes promise to unveil the genetic mechanisms controlling developmental plasticity and provide a paradigm for the principles governing evolutionary modification of an embryonic GRN.
Collapse
Affiliation(s)
- Chee Kiang Ewe
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
| | | | - Joel H. Rothman
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| |
Collapse
|
15
|
Garrigues JM, Tsu BV, Daugherty MD, Pasquinelli AE. Diversification of the Caenorhabditis heat shock response by Helitron transposable elements. eLife 2019; 8:51139. [PMID: 31825311 PMCID: PMC6927752 DOI: 10.7554/elife.51139] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/10/2019] [Indexed: 12/15/2022] Open
Abstract
Heat Shock Factor 1 (HSF-1) is a key regulator of the heat shock response (HSR). Upon heat shock, HSF-1 binds well-conserved motifs, called Heat Shock Elements (HSEs), and drives expression of genes important for cellular protection during this stress. Remarkably, we found that substantial numbers of HSEs in multiple Caenorhabditis species reside within Helitrons, a type of DNA transposon. Consistent with Helitron-embedded HSEs being functional, upon heat shock they display increased HSF-1 and RNA polymerase II occupancy and up-regulation of nearby genes in C. elegans. Interestingly, we found that different genes appear to be incorporated into the HSR by species-specific Helitron insertions in C. elegans and C. briggsae and by strain-specific insertions among different wild isolates of C. elegans. Our studies uncover previously unidentified targets of HSF-1 and show that Helitron insertions are responsible for rewiring and diversifying the Caenorhabditis HSR.
Collapse
Affiliation(s)
- Jacob M Garrigues
- Division of Biology, University of California, San Diego, San Diego, United States
| | - Brian V Tsu
- Division of Biology, University of California, San Diego, San Diego, United States
| | - Matthew D Daugherty
- Division of Biology, University of California, San Diego, San Diego, United States
| | - Amy E Pasquinelli
- Division of Biology, University of California, San Diego, San Diego, United States
| |
Collapse
|
16
|
Rödelsperger C, Athanasouli M, Lenuzzi M, Theska T, Sun S, Dardiry M, Wighard S, Hu W, Sharma DR, Han Z. Crowdsourcing and the feasibility of manual gene annotation: A pilot study in the nematode Pristionchus pacificus. Sci Rep 2019; 9:18789. [PMID: 31827189 PMCID: PMC6906410 DOI: 10.1038/s41598-019-55359-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/20/2019] [Indexed: 01/15/2023] Open
Abstract
Nematodes such as Caenorhabditis elegans are powerful systems to study basically all aspects of biology. Their species richness together with tremendous genetic knowledge from C. elegans facilitate the evolutionary study of biological functions using reverse genetics. However, the ability to identify orthologs of candidate genes in other species can be hampered by erroneous gene annotations. To improve gene annotation in the nematode model organism Pristionchus pacificus, we performed a genome-wide screen for C. elegans genes with potentially incorrectly annotated P. pacificus orthologs. We initiated a community-based project to manually inspect more than two thousand candidate loci and to propose new gene models based on recently generated Iso-seq and RNA-seq data. In most cases, misannotation of C. elegans orthologs was due to artificially fused gene predictions and completely missing gene models. The community-based curation raised the gene count from 25,517 to 28,036 and increased the single copy ortholog completeness level from 86% to 97%. This pilot study demonstrates how even small-scale crowdsourcing can drastically improve gene annotations. In future, similar approaches can be used for other species, gene sets, and even larger communities thus making manual annotation of large parts of the genome feasible.
Collapse
Affiliation(s)
- Christian Rödelsperger
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany.
| | - Marina Athanasouli
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Maša Lenuzzi
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Tobias Theska
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Shuai Sun
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Mohannad Dardiry
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Sara Wighard
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Wen Hu
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Devansh Raj Sharma
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Ziduan Han
- Max Planck Institute for Developmental Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| |
Collapse
|
17
|
Interplay between Developmental Flexibility and Determinism in the Evolution of Mimetic Heliconius Wing Patterns. Curr Biol 2019; 29:3996-4009.e4. [DOI: 10.1016/j.cub.2019.10.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/26/2019] [Accepted: 10/08/2019] [Indexed: 11/20/2022]
|
18
|
Colgan W, Leanza A, Hwang A, DeBiasse MB, Llosa I, Rodrigues D, Adhikari H, Barreto Corona G, Bock S, Carillo-Perez A, Currie M, Darkoa-Larbi S, Dellal D, Gutow H, Hokama P, Kibby E, Linhart N, Moody S, Naganuma A, Nguyen D, Stanton R, Stark S, Tumey C, Velleca A, Ryan JF, Davidson B. Variable levels of drift in tunicate cardiopharyngeal gene regulatory elements. EvoDevo 2019; 10:24. [PMID: 31632631 PMCID: PMC6790052 DOI: 10.1186/s13227-019-0137-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/13/2019] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Mutations in gene regulatory networks often lead to genetic divergence without impacting gene expression or developmental patterning. The rules governing this process of developmental systems drift, including the variable impact of selective constraints on different nodes in a gene regulatory network, remain poorly delineated. RESULTS Here we examine developmental systems drift within the cardiopharyngeal gene regulatory networks of two tunicate species, Corella inflata and Ciona robusta. Cross-species analysis of regulatory elements suggests that trans-regulatory architecture is largely conserved between these highly divergent species. In contrast, cis-regulatory elements within this network exhibit distinct levels of conservation. In particular, while most of the regulatory elements we analyzed showed extensive rearrangements of functional binding sites, the enhancer for the cardiopharyngeal transcription factor FoxF is remarkably well-conserved. Even minor alterations in spacing between binding sites lead to loss of FoxF enhancer function, suggesting that bound trans-factors form position-dependent complexes. CONCLUSIONS Our findings reveal heterogeneous levels of divergence across cardiopharyngeal cis-regulatory elements. These distinct levels of divergence presumably reflect constraints that are not clearly associated with gene function or position within the regulatory network. Thus, levels of cis-regulatory divergence or drift appear to be governed by distinct structural constraints that will be difficult to predict based on network architecture.
Collapse
Affiliation(s)
| | - Alexis Leanza
- Thomas Jefferson University Sidney Kimmel Medical College, Philadelphia, USA
| | - Ariel Hwang
- University of North Carolina, Chapel Hill, USA
| | | | | | | | | | | | | | | | | | | | - Daniel Dellal
- Icahn School of Medicine at Mount Sinai, New York, USA
| | | | | | - Emily Kibby
- University of Colorado Boulder, Boulder, USA
| | | | | | | | | | | | - Sierra Stark
- University of California San Francisco, San Francisco, USA
| | | | | | - Joseph F. Ryan
- Whitney Laboratory for Marine Bioscience, St. Augustine, USA
| | | |
Collapse
|
19
|
Cutter AD, Garrett RH, Mark S, Wang W, Sun L. Molecular evolution across developmental time reveals rapid divergence in early embryogenesis. Evol Lett 2019; 3:359-373. [PMID: 31388446 PMCID: PMC6675142 DOI: 10.1002/evl3.122] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/30/2019] [Indexed: 12/16/2022] Open
Abstract
Ontogenetic development hinges on the changes in gene expression in time and space within an organism, suggesting that the demands of ontogenetic growth can impose or reveal predictable pattern in the molecular evolution of genes expressed dynamically across development. Here, we characterize coexpression modules of the Caenorhabditis elegans transcriptome, using a time series of 30 points from early embryo to adult. By capturing the functional form of expression profiles with quantitative metrics, we find fastest evolution in the distinctive set of genes with transcript abundance that declines through development from a peak in young embryos. These genes are highly enriched for oogenic function and transient early zygotic expression, are nonrandomly distributed in the genome, and correspond to a life stage especially prone to inviability in interspecies hybrids. These observations conflict with the "early conservation model" for the evolution of development, although expression-weighted sequence divergence analysis provides some support for the "hourglass model." Genes in coexpression modules that peak toward adulthood also evolve fast, being hyper-enriched for roles in spermatogenesis, implicating a history of sexual selection and relaxation of selection on sperm as key factors driving rapid change to ontogenetically distinguishable coexpression modules of genes. We propose that these predictable trends of molecular evolution for dynamically expressed genes across ontogeny predispose particular life stages, early embryogenesis in particular, to hybrid dysfunction in the speciation process.
Collapse
Affiliation(s)
- Asher D. Cutter
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONM6G1W3Canada
| | - Rose H. Garrett
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONM6G1W3Canada
- Division of Biostatistics, Dalla Lana School of Public HealthUniversity of TorontoTorontoONM6G1W3Canada
- Department of Statistical SciencesUniversity of TorontoTorontoONM6G1W3Canada
| | - Stephanie Mark
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONM6G1W3Canada
| | - Wei Wang
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONM6G1W3Canada
| | - Lei Sun
- Division of Biostatistics, Dalla Lana School of Public HealthUniversity of TorontoTorontoONM6G1W3Canada
- Department of Statistical SciencesUniversity of TorontoTorontoONM6G1W3Canada
| |
Collapse
|
20
|
Khatri BS, Goldstein RA. Biophysics and population size constrains speciation in an evolutionary model of developmental system drift. PLoS Comput Biol 2019; 15:e1007177. [PMID: 31335870 PMCID: PMC6677325 DOI: 10.1371/journal.pcbi.1007177] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 08/02/2019] [Accepted: 06/13/2019] [Indexed: 02/06/2023] Open
Abstract
Developmental system drift is a likely mechanism for the origin of hybrid incompatibilities between closely related species. We examine here the detailed mechanistic basis of hybrid incompatibilities between two allopatric lineages, for a genotype-phenotype map of developmental system drift under stabilising selection, where an organismal phenotype is conserved, but the underlying molecular phenotypes and genotype can drift. This leads to number of emergent phenomenon not obtainable by modelling genotype or phenotype alone. Our results show that: 1) speciation is more rapid at smaller population sizes with a characteristic, Orr-like, power law, but at large population sizes slow, characterised by a sub-diffusive growth law; 2) the molecular phenotypes under weakest selection contribute to the earliest incompatibilities; and 3) pair-wise incompatibilities dominate over higher order, contrary to previous predictions that the latter should dominate. The population size effect we find is consistent with previous results on allopatric divergence of transcription factor-DNA binding, where smaller populations have common ancestors with a larger drift load because genetic drift favours phenotypes which have a larger number of genotypes (higher sequence entropy) over more fit phenotypes which have far fewer genotypes; this means less substitutions are required in either lineage before incompatibilities arise. Overall, our results indicate that biophysics and population size provide a much stronger constraint to speciation than suggested by previous models, and point to a general mechanistic principle of how incompatibilities arise the under stabilising selection for an organismal phenotype. The process of speciation is of fundamental importance to the field of evolution as it is intimately connected to understanding the immense bio-diversity of life. There is still relatively little understanding of the underlying genetic mechanisms that give rise to hybrid incompatibilities with results suggesting that divergence in transcription factor DNA binding and gene expression play an important role. A key finding from the field of evo-devo is that organismal phenotypes show developmental system drift, where species maintain the same phenotype, but diverge in developmental pathways; this is an important potential source of hybrid incompatibilities. Here, we explore a theoretical framework to understand how incompatibilities arise due to developmental system drift, using a tractable biophysically inspired genotype-phenotype for spatial gene expression. Modelling the evolution of phenotypes in this way has the key advantage that it mirrors how selection works in nature, i.e. that selection acts on phenotypes, but variation (mutation) arise at the level of genotypes. This results, as we demonstrate, in a number of non-trivial and testable predictions concerning speciation due to developmental system drift, which would not be obtainable by modelling evolution of genotypes or phenotypes alone.
Collapse
Affiliation(s)
| | - Richard A. Goldstein
- Division of Infection & Immunity, University College London, London, United Kingdom
| |
Collapse
|
21
|
An Evaluation of Machine Learning Approaches for the Prediction of Essential Genes in Eukaryotes Using Protein Sequence-Derived Features. Comput Struct Biotechnol J 2019; 17:785-796. [PMID: 31312416 PMCID: PMC6607062 DOI: 10.1016/j.csbj.2019.05.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/23/2019] [Accepted: 05/26/2019] [Indexed: 12/23/2022] Open
Abstract
The availability of whole-genome sequences and associated multi-omics data sets, combined with advances in gene knockout and knockdown methods, has enabled large-scale annotation and exploration of gene and protein functions in eukaryotes. Knowing which genes are essential for the survival of eukaryotic organisms is paramount for an understanding of the basic mechanisms of life, and could assist in identifying intervention targets in eukaryotic pathogens and cancer. Here, we studied essential gene orthologs among selected species of eukaryotes, and then employed a systematic machine-learning approach, using protein sequence-derived features and selection procedures, to investigate essential gene predictions within and among species. We showed that the numbers of essential gene orthologs comprise small fractions when compared with the total number of orthologs among the eukaryotic species studied. In addition, we demonstrated that machine-learning models trained with subsets of essentiality-related data performed better than random guessing of gene essentiality for a particular species. Consistent with our gene ortholog analysis, the predictions of essential genes among multiple (including distantly-related) species is possible, yet challenging, suggesting that most essential genes are unique to a species. The present work provides a foundation for the expansion of genome-wide essentiality investigations in eukaryotes using machine learning approaches.
Collapse
Key Words
- CRISPR, Clustered regularly interspaced short palindromic repeats
- Essential genes
- Essentiality prediction
- Eukaryotes
- GBM, Gradient boosting method
- GI, Genetic interaction
- GLM, Generalised linear model
- GO, Gene ontology
- ML, Machine-learning
- Machine-learning
- NN, Artificial neural network
- OGEE, Online GEne essentiality database
- PPI, Protein-protein interaction
- PR-AUC, Area under the precision-recall curve
- RF, Random Forest
- RNAi, RNA interference
- ROC-AUC, Area under the receiver operating characteristic curve
- SPLS, Sparse partial least squares
- SVM, Support-Vector machine
Collapse
|
22
|
Memar N, Schiemann S, Hennig C, Findeis D, Conradt B, Schnabel R. Twenty million years of evolution: The embryogenesis of four Caenorhabditis species are indistinguishable despite extensive genome divergence. Dev Biol 2019; 447:182-199. [DOI: 10.1016/j.ydbio.2018.12.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 12/19/2022]
|
23
|
Haag ES, Fitch DHA, Delattre M. From "the Worm" to "the Worms" and Back Again: The Evolutionary Developmental Biology of Nematodes. Genetics 2018; 210:397-433. [PMID: 30287515 PMCID: PMC6216592 DOI: 10.1534/genetics.118.300243] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 08/03/2018] [Indexed: 12/13/2022] Open
Abstract
Since the earliest days of research on nematodes, scientists have noted the developmental and morphological variation that exists within and between species. As various cellular and developmental processes were revealed through intense focus on Caenorhabditis elegans, these comparative studies have expanded. Within the genus Caenorhabditis, they include characterization of intraspecific polymorphisms and comparisons of distinct species, all generally amenable to the same laboratory culture methods and supported by robust genomic and experimental tools. The C. elegans paradigm has also motivated studies with more distantly related nematodes and animals. Combined with improved phylogenies, this work has led to important insights about the evolution of nematode development. First, while many aspects of C. elegans development are representative of Caenorhabditis, and of terrestrial nematodes more generally, others vary in ways both obvious and cryptic. Second, the system has revealed several clear examples of developmental flexibility in achieving a particular trait. This includes developmental system drift, in which the developmental control of homologous traits has diverged in different lineages, and cases of convergent evolution. Overall, the wealth of information and experimental techniques developed in C. elegans is being leveraged to make nematodes a powerful system for evolutionary cellular and developmental biology.
Collapse
Affiliation(s)
- Eric S Haag
- Department of Biology, University of Maryland, College Park, Maryland 20742
| | | | - Marie Delattre
- Laboratoire de Biologie Moléculaire de la Cellule, CNRS, INSERM, Ecole Normale Supérieure de Lyon, 69007, France
| |
Collapse
|
24
|
Valfort AC, Launay C, Sémon M, Delattre M. Evolution of mitotic spindle behavior during the first asymmetric embryonic division of nematodes. PLoS Biol 2018; 16:e2005099. [PMID: 29357348 PMCID: PMC5794175 DOI: 10.1371/journal.pbio.2005099] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/01/2018] [Accepted: 01/03/2018] [Indexed: 01/08/2023] Open
Abstract
Asymmetric cell division is essential to generate cellular diversity. In many animal cells, the cleavage plane lies perpendicular to the mitotic spindle, and it is the spindle positioning that dictates the size of the daughter cells. Although some properties of spindle positioning are conserved between distantly related model species and different cell types, little is known of the evolutionary robustness of the mechanisms underlying this event. We recorded the first embryonic division of 42 species of nematodes closely related to Caenorhabditis elegans, which is an excellent model system to study the biophysical properties of asymmetric spindle positioning. Our recordings, corresponding to 128 strains from 27 Caenorhabditis and 15 non-Caenorhabditis species (accessible at http://www.ens-lyon.fr/LBMC/NematodeCell/videos/), constitute a powerful collection of subcellular phenotypes to study the evolution of various cellular processes across species. In the present work, we analyzed our collection to the study of asymmetric spindle positioning. Although all the strains underwent an asymmetric first cell division, they exhibited large intra- and inter-species variations in the degree of cell asymmetry and in several parameters controlling spindle movement, including spindle oscillation, elongation, and displacement. Notably, these parameters changed frequently during evolution with no apparent directionality in the species phylogeny, with the exception of spindle transverse oscillations, which were an evolutionary innovation at the base of the Caenorhabditis genus. These changes were also unrelated to evolutionary variations in embryo size. Importantly, spindle elongation, displacement, and oscillation each evolved independently. This finding contrasts starkly with expectations based on C. elegans studies and reveals previously unrecognized evolutionary changes in spindle mechanics. Collectively, these data demonstrate that, while the essential process of asymmetric cell division has been conserved over the course of nematode evolution, the underlying spindle movement parameters can combine in various ways. Like other developmental processes, asymmetric cell division is subject to system drift.
Collapse
Affiliation(s)
- Aurore-Cécile Valfort
- Department of Pharmacology & Physiology (Colin Flaveny lab), Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Caroline Launay
- UnivLyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
| | - Marie Sémon
- UnivLyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
| | - Marie Delattre
- UnivLyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
| |
Collapse
|
25
|
Abstract
Nematodes, such as Caenorhabditis elegans, form one of the most species-rich animal phyla. By now more than 30 nematode genomes have been published allowing for comparative genomic analyses at various different time-scales. The majority of a nematode's gene repertoire is represented by either duplicated or so-called orphan genes of unknown origin. This indicates the importance of mechanisms that generate new genes during the course of evolution. While it is certain that nematodes have acquired genes by horizontal gene transfer from various donors, this process only explains a small portion of the nematode gene content. As evolutionary genomic analyses strongly support that most orphan genes are indeed protein-coding, future studies will have to decide, whether they are result from extreme divergence or evolved de novo from previously noncoding sequences. In this contribution, I summarize several studies investigating gene loss and gain in nematodes and discuss the strengths and weaknesses of individual approaches and datasets. These approaches can be used to ask nematode-specific questions such as associated with the evolution of parasitism or with switches in mating systems, but also can complement studies in other animal phyla like vertebrates and insects to broaden our general view on genome evolution.
Collapse
Affiliation(s)
- Christian Rödelsperger
- Department for Evolutionary Biology, Max Planck Institute for Developmental Biology, Spemannstr. 35, 72076, Tübingen, Germany.
| |
Collapse
|
26
|
Buffry AD, Mendes CC, McGregor AP. The Functionality and Evolution of Eukaryotic Transcriptional Enhancers. ADVANCES IN GENETICS 2016; 96:143-206. [PMID: 27968730 DOI: 10.1016/bs.adgen.2016.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enhancers regulate precise spatial and temporal patterns of gene expression in eukaryotes and, moreover, evolutionary changes in these modular cis-regulatory elements may represent the predominant genetic basis for phenotypic evolution. Here, we review approaches to identify and functionally analyze enhancers and their transcription factor binding sites, including assay for transposable-accessible chromatin-sequencing (ATAC-Seq) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9, respectively. We also explore enhancer functionality, including how transcription factor binding sites combine to regulate transcription, as well as research on shadow and super enhancers, and how enhancers can act over great distances and even in trans. Finally, we discuss recent theoretical and empirical data on how transcription factor binding sites and enhancers evolve. This includes how the function of enhancers is maintained despite the turnover of transcription factor binding sites as well as reviewing studies where mutations in enhancers have been shown to underlie morphological change.
Collapse
Affiliation(s)
- A D Buffry
- Oxford Brookes University, Oxford, United Kingdom
| | - C C Mendes
- Oxford Brookes University, Oxford, United Kingdom
| | - A P McGregor
- Oxford Brookes University, Oxford, United Kingdom
| |
Collapse
|
27
|
Paaby AB, Gibson G. Cryptic Genetic Variation in Evolutionary Developmental Genetics. BIOLOGY 2016; 5:E28. [PMID: 27304973 PMCID: PMC4929542 DOI: 10.3390/biology5020028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/01/2016] [Accepted: 06/06/2016] [Indexed: 01/17/2023]
Abstract
Evolutionary developmental genetics has traditionally been conducted by two groups: Molecular evolutionists who emphasize divergence between species or higher taxa, and quantitative geneticists who study variation within species. Neither approach really comes to grips with the complexities of evolutionary transitions, particularly in light of the realization from genome-wide association studies that most complex traits fit an infinitesimal architecture, being influenced by thousands of loci. This paper discusses robustness, plasticity and lability, phenomena that we argue potentiate major evolutionary changes and provide a bridge between the conceptual treatments of macro- and micro-evolution. We offer cryptic genetic variation and conditional neutrality as mechanisms by which standing genetic variation can lead to developmental system drift and, sheltered within canalized processes, may facilitate developmental transitions and the evolution of novelty. Synthesis of the two dominant perspectives will require recognition that adaptation, divergence, drift and stability all depend on similar underlying quantitative genetic processes-processes that cannot be fully observed in continuously varying visible traits.
Collapse
Affiliation(s)
- Annalise B Paaby
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| | - Greg Gibson
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| |
Collapse
|
28
|
Plasticity in the Meiotic Epigenetic Landscape of Sex Chromosomes in Caenorhabditis Species. Genetics 2016; 203:1641-58. [PMID: 27280692 DOI: 10.1534/genetics.116.191130] [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: 04/30/2016] [Accepted: 06/06/2016] [Indexed: 01/19/2023] Open
Abstract
During meiosis in the heterogametic sex in some species, sex chromosomes undergo meiotic sex chromosome inactivation (MSCI), which results in acquisition of repressive chromatin and transcriptional silencing. In Caenorhabditis elegans, MSCI is mediated by MET-2 methyltransferase deposition of histone H3 lysine 9 dimethylation. Here we examined the meiotic chromatin landscape in germ lines of four Caenorhabditis species; C. remanei and C. brenneri represent ancestral gonochorism, while C. briggsae and C. elegans are two lineages that independently evolved hermaphroditism. While MSCI is conserved across all four species, repressive chromatin modifications are distinct and do not correlate with reproductive mode. In contrast to C. elegans and C. remanei germ cells where X chromosomes are enriched for histone H3 lysine 9 dimethylation, X chromosomes in C. briggsae and C. brenneri germ cells are enriched for histone H3 lysine 9 trimethylation. Inactivation of C. briggsae MET-2 resulted in germ-line X chromosome transcription and checkpoint activation. Further, both histone H3 lysine 9 di- and trimethylation were reduced in Cbr-met-2 mutant germ lines, suggesting that in contrast to C. elegans, H3 lysine 9 di- and trimethylation are interdependent. C. briggsae H3 lysine 9 trimethylation was redistributed in the presence of asynapsed chromosomes in a sex-specific manner in the related process of meiotic silencing of unsynapsed chromatin. However, these repressive marks did not influence X chromosome replication timing. Examination of additional Caenorhabditis species revealed diverse H3 lysine 9 methylation patterns on the X, suggesting that the sex chromosome epigenome evolves rapidly.
Collapse
|
29
|
Prabh N, Rödelsperger C. Are orphan genes protein-coding, prediction artifacts, or non-coding RNAs? BMC Bioinformatics 2016; 17:226. [PMID: 27245157 PMCID: PMC4888513 DOI: 10.1186/s12859-016-1102-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/24/2016] [Indexed: 12/26/2022] Open
Abstract
Background Current genome sequencing projects reveal substantial numbers of taxonomically restricted, so called orphan genes that lack homology with genes from other evolutionary lineages. However, it is not clear to what extent orphan genes are real, genomic artifacts, or represent non-coding RNAs. Results Here, we use a simple set of assumptions to test the nature of orphan genes. First, a sequence that is transcribed is considered a real biological entity. Second, every sequence that is supported by proteome data or shows a depletion of non-synonymous substitutions is a protein-coding gene. Using genomic, transcriptomic and proteomic data for the nematode Pristionchus pacificus, we show that between 4129–7997 (42–81 %) of predicted orphan genes are expressed and 3818–7545 (39–76 %) of orphan genes are under negative selection. In three cases that exhibited strong evolutionary constraint but lacked expression evidence in 14 RNA-seq samples, we could experimentally validate the predicted gene structures. Comparing different data sets to infer selection on orphan gene clusters, we find that the presence of a closely related genome provides the most powerful resource to robustly identify evidence of negative selection. However, even in the absence of other genomic data, the availability of paralogous sequences was enough to show negative selection in 8–10 % of orphan genes. Conclusions Our study shows that the great majority of previously identified orphan genes in P. pacificus are indeed protein-coding genes. Even though this work represents a case study on a single species, our approach can be transferred to genomic data of other non-model organisms in order to ascertain the protein-coding nature of orphan genes.
Collapse
Affiliation(s)
- Neel Prabh
- Department for Evolutionary Biology, Max-Planck-Institute for Developmental Biology, Spemannstrasse 35, 72076, Tübingen, Germany
| | - Christian Rödelsperger
- Department for Evolutionary Biology, Max-Planck-Institute for Developmental Biology, Spemannstrasse 35, 72076, Tübingen, Germany.
| |
Collapse
|
30
|
Martin E, Rocheleau-Leclair O, Jenna S. Novel Metrics to Characterize Embryonic Elongation of the Nematode Caenorhabditis elegans. J Vis Exp 2016:e53712. [PMID: 27077374 DOI: 10.3791/53712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Dissecting the signaling pathways that control the alteration of morphogenic processes during embryonic development requires robust and sensitive metrics. Embryonic elongation of the nematode Caenorhabditis elegans is a late developmental stage consisting of the elongation of the embryo along its longitudinal axis. This developmental stage is controlled by intercellular communication between hypodermal cells and underlying body-wall muscles. These signaling mechanisms control the morphology of hypodermal cells by remodeling the cytoskeleton and the cell-cell junctions. Measurement of embryonic lethality and developmental arrest at larval stages as well as alteration of cytoskeleton and cell-cell adhesion structures in hypodermal and muscle cells are classical phenotypes that have been used for more than 25 years to dissect these signaling pathways. Recent studies required the development of novel metrics specifically targeting either early or late elongation and characterizing morphogenic defects along the antero-posterior axis of the embryo. Here, we provide detailed protocols enabling the accurate measurement of the length and the width of the elongating embryos as well as the length of synchronized larvae. These methods constitute useful tools to identify genes controlling elongation, to assess whether these genes control both early and late phases of this stage and are required evenly along the antero-posterior axis of the embryo.
Collapse
Affiliation(s)
- Emmanuel Martin
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal
| | | | - Sarah Jenna
- Department of Chemistry, Pharmaqam, Université du Québec à Montréal;
| |
Collapse
|
31
|
Lightfoot JW, Chauhan VM, Aylott JW, Rödelsperger C. Comparative transcriptomics of the nematode gut identifies global shifts in feeding mode and pathogen susceptibility. BMC Res Notes 2016; 9:142. [PMID: 26944260 PMCID: PMC4779222 DOI: 10.1186/s13104-016-1886-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 01/25/2016] [Indexed: 12/20/2022] Open
Abstract
Background The nematode Pristionchus pacificus has been established as a model for comparative studies using the well known Caenorhabditis elegans as a reference. Despite their relatedness, previous studies have revealed highly divergent development and a number of morphological differences including the lack of a pharyngal structure, the grinder, used to physically lyse the ingested bacteria in C. elegans. Results To complement current knowledge about developmental and ecological differences with a better understanding of their feeding modes, we have sequenced the intestinal transcriptomes of both nematodes. In total, we found 464 intestine-enriched genes in P. pacificus and 724 in C. elegans, of which the majority (66 %) has been identified by previous studies. Interestingly, only 15 genes could be identified with shared intestinal enrichment in both species, of which three genes are Hedgehog signaling molecules supporting a highly conserved role of this pathway for intestinal development across all metazoa. At the level of gene families, we find similar divergent trends with only five families displaying significant intestinal enrichment in both species. We compared our data with transcriptomic responses to various pathogens. Strikingly, C. elegans intestine-enriched genes showed highly significant overlaps with pathogen response genes whereas this was not the case for P. pacificus, indicating shifts in pathogen susceptibility that might be explained by altered feeding modes. Conclusions Our study reveals first insights into the evolution of feeding systems and the associated changes in intestinal gene expression that might have facilitated nematodes of the P. pacificus lineage to colonize new environments. These findings deepen our understanding about how morphological and genomic diversity is created during the course of evolution. Electronic supplementary material The online version of this article (doi:10.1186/s13104-016-1886-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- James W Lightfoot
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstr. 35-39, Tübingen, Germany.
| | - Veeren M Chauhan
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Boots Science Building, Nottingham, UK.
| | - Jonathan W Aylott
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Boots Science Building, Nottingham, UK.
| | - Christian Rödelsperger
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstr. 35-39, Tübingen, Germany.
| |
Collapse
|
32
|
Fischer EK. Flexibility and Constraint in the Evolution of Gene Expression and Behavior. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:1-3. [PMID: 26771304 DOI: 10.1159/000442436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Eva K Fischer
- Department of Biology, Colorado State University, Fort Collins, Colo., USA
| |
Collapse
|
33
|
Gehrke AR, Shubin NH. Cis-regulatory programs in the development and evolution of vertebrate paired appendages. Semin Cell Dev Biol 2016; 57:31-39. [PMID: 26783722 DOI: 10.1016/j.semcdb.2016.01.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 02/02/2023]
Abstract
Differential gene expression is the core of development, mediating the genetic changes necessary for determining cell identity. The regulation of gene activity by cis-acting elements (e.g., enhancers) is a crucial mechanism for determining differential gene activity by precise control of gene expression in embryonic space and time. Modifications to regulatory regions can have profound impacts on phenotype, and therefore developmental and evolutionary biologists have increasingly focused on elucidating the transcriptional control of genes that build and pattern body plans. Here, we trace the evolutionary history of transcriptional control of three loci key to vertebrate appendage development (Fgf8, Shh, and HoxD/A). Within and across these regulatory modules, we find both complex and flexible regulation in contrast with more fixed enhancers that appear unchanged over vast timescales of vertebrate evolution. The transcriptional control of vertebrate appendage development was likely already incredibly complex in the common ancestor of fish, implying that subtle changes to regulatory networks were more likely responsible for alterations in phenotype rather than the de novo addition of whole regulatory domains. Finally, we discuss the dangers of relying on inter-species transgenesis when testing enhancer function, and call for more controlled regulatory swap experiments when inferring the evolutionary history of enhancer elements.
Collapse
Affiliation(s)
- Andrew R Gehrke
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL 60637, USA.
| | - Neil H Shubin
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL 60637, USA.
| |
Collapse
|
34
|
Filteau M, Hamel V, Pouliot MC, Gagnon-Arsenault I, Dubé AK, Landry CR. Evolutionary rescue by compensatory mutations is constrained by genomic and environmental backgrounds. Mol Syst Biol 2015; 11:832. [PMID: 26459777 PMCID: PMC4631203 DOI: 10.15252/msb.20156444] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Since deleterious mutations may be rescued by secondary mutations during evolution, compensatory evolution could identify genetic solutions leading to therapeutic targets. Here, we tested this hypothesis and examined whether these solutions would be universal or would need to be adapted to one's genetic and environmental makeups. We performed experimental evolutionary rescue in a yeast disease model for the Wiskott–Aldrich syndrome in two genetic backgrounds and carbon sources. We found that multiple aspects of the evolutionary rescue outcome depend on the genotype, the environment, or a combination thereof. Specifically, the compensatory mutation rate and type, the molecular rescue mechanism, the genetic target, and the associated fitness cost varied across contexts. The course of compensatory evolution is therefore highly contingent on the initial conditions in which the deleterious mutation occurs. In addition, these results reveal biologically favored therapeutic targets for the Wiskott–Aldrich syndrome, including the target of an unrelated clinically approved drug. Our results experimentally illustrate the importance of epistasis and environmental evolutionary constraints that shape the adaptive landscape and evolutionary rate of molecular networks.
Collapse
Affiliation(s)
- Marie Filteau
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| | - Véronique Hamel
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| | - Marie-Christine Pouliot
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| | - Isabelle Gagnon-Arsenault
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| | - Alexandre K Dubé
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| | - Christian R Landry
- Département de Biologie, PROTEO and Institut de Biologie Intégrative et des Systèmes (IBIS) Université Laval, Québec, Qc, Canada
| |
Collapse
|
35
|
Abstract
It is tempting to invoke organismal selection as perpetually optimizing the function of any given gene. However, natural selection can drive genic functional change without improvement of biochemical activity, even to the extinction of gene activity. Detrimental mutations can creep in owing to linkage with other selectively favored loci. Selection can promote functional degradation, irrespective of genetic drift, when adaptation occurs by loss of gene function. Even stabilizing selection on a trait can lead to divergence of the underlying molecular constituents. Selfish genetic elements can also proliferate independent of any functional benefits to the host genome. Here we review the logic and evidence for these diverse processes acting in genome evolution. This collection of distinct evolutionary phenomena - while operating through easily understandable mechanisms - all contribute to the seemingly counterintuitive notion that maintenance or improvement of a gene's biochemical function sometimes do not determine its evolutionary fate.
Collapse
Affiliation(s)
- Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Richard Jovelin
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
36
|
Paaby AB, White AG, Riccardi DD, Gunsalus KC, Piano F, Rockman MV. Wild worm embryogenesis harbors ubiquitous polygenic modifier variation. eLife 2015; 4. [PMID: 26297805 PMCID: PMC4569889 DOI: 10.7554/elife.09178] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/21/2015] [Indexed: 12/28/2022] Open
Abstract
Embryogenesis is an essential and stereotypic process that nevertheless evolves
among species. Its essentiality may favor the accumulation of cryptic genetic
variation (CGV) that has no effect in the wild-type but that enhances or
suppresses the effects of rare disruptions to gene function. Here, we adapted a
classical modifier screen to interrogate the alleles segregating in natural
populations of Caenorhabditis elegans: we induced gene
knockdowns and used quantitative genetic methodology to examine how segregating
variants modify the penetrance of embryonic lethality. Each perturbation
revealed CGV, indicating that wild-type genomes harbor myriad genetic modifiers
that may have little effect individually but which in aggregate can dramatically
influence penetrance. Phenotypes were mediated by many modifiers, indicating
high polygenicity, but the alleles tend to act very specifically, indicating low
pleiotropy. Our findings demonstrate the extent of conditional functionality in
complex trait architecture. DOI:http://dx.doi.org/10.7554/eLife.09178.001 Individuals of the same species have similar, but generally not identical, DNA
sequences. This ‘genetic variation’ is due to random changes in the DNA—known as
mutations—that occur among individuals. These mutations may be passed on to
these individuals' offspring, who in turn pass them on to their descendants.
Some of these mutations may have a positive or negative effect on the ability of
the organisms to survive and reproduce, but others may have no effect at
all. The process by which an embryo forms (which is called embryogenesis) follows a
precisely controlled series of events. Within the same species, there is genetic
variation in the DNA that programs embryogenesis, but it is not clear what
effect this variation has on how the embryo develops. Here, Paaby et al. adapted
a genetics technique called a ‘modifier screen’ to study how genetic variation
affects the development of a roundworm known as Caenorhabditis
elegans. The experiments show that populations of worms harbor a lot of genetic variation
that affects how they tolerate the loss of an important gene. One by one, Paaby
et al. interrupted the activity of specific genes that embryos need in order to
develop. How this affected the embryo, and whether or not it was able to
survive, was due in large part to the naturally-occurring genetic variation in
other genes in these worms. Paaby et al.'s findings serve as a reminder that the effect of a mutation depends
on other DNA sequences in the organism. In humans, for example, a gene that
causes a genetic disease may produce severe symptoms in one patient but mild
symptoms in another. Future experiments will reveal the details of how genetic
variation affects embryogenesis, which may also provide new insights into how
complex processes in animals evolve over time. DOI:http://dx.doi.org/10.7554/eLife.09178.002
Collapse
Affiliation(s)
- Annalise B Paaby
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| | - Amelia G White
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| | - David D Riccardi
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| | - Kristin C Gunsalus
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| | - Fabio Piano
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| | - Matthew V Rockman
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, United States
| |
Collapse
|
37
|
Moczek AP, Sears KE, Stollewerk A, Wittkopp PJ, Diggle P, Dworkin I, Ledon-Rettig C, Matus DQ, Roth S, Abouheif E, Brown FD, Chiu CH, Cohen CS, Tomaso AWD, Gilbert SF, Hall B, Love AC, Lyons DC, Sanger TJ, Smith J, Specht C, Vallejo-Marin M, Extavour CG. The significance and scope of evolutionary developmental biology: a vision for the 21st century. Evol Dev 2015; 17:198-219. [PMID: 25963198 DOI: 10.1111/ede.12125] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Evolutionary developmental biology (evo-devo) has undergone dramatic transformations since its emergence as a distinct discipline. This paper aims to highlight the scope, power, and future promise of evo-devo to transform and unify diverse aspects of biology. We articulate key questions at the core of eleven biological disciplines-from Evolution, Development, Paleontology, and Neurobiology to Cellular and Molecular Biology, Quantitative Genetics, Human Diseases, Ecology, Agriculture and Science Education, and lastly, Evolutionary Developmental Biology itself-and discuss why evo-devo is uniquely situated to substantially improve our ability to find meaningful answers to these fundamental questions. We posit that the tools, concepts, and ways of thinking developed by evo-devo have profound potential to advance, integrate, and unify biological sciences as well as inform policy decisions and illuminate science education. We look to the next generation of evolutionary developmental biologists to help shape this process as we confront the scientific challenges of the 21st century.
Collapse
Affiliation(s)
- Armin P Moczek
- Department of Biology, Indiana University, 915 East 3rd Street, Bloomington, IN 47405, USA
| | - Karen E Sears
- School of Integrative Biology and Institute for Genomic Biology, University of Illinois, 505 South Goodwin Avenue, Urbana, IL, 61801, USA
| | - Angelika Stollewerk
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS, UK
| | - Patricia J Wittkopp
- Department of Ecology and Evolutionary Biology, Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Pamela Diggle
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA
| | - Ian Dworkin
- Department of Biology, McMaster University, 1280 Main St. West Hamilton, Ontario, L8S 4K1, Canada
| | - Cristina Ledon-Rettig
- Department of Biology, Indiana University, 915 East 3rd Street, Bloomington, IN 47405, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, 412 Life Sciences Building, Stony Brook, NY, 11794-5215, USA
| | - Siegfried Roth
- University of Cologne, Institute of Developmental Biology, Biocenter, Zülpicher Straße 47b, D-50674, Cologne, Germany
| | - Ehab Abouheif
- Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montréal Québec, H3A 1B1, Canada
| | - Federico D Brown
- Departamento de Zoologia, Instituto Biociências, Universidade de São Paulo, Rua do Matão, Travessa 14, no. 101, 05508-090, São Paulo, Brazil
| | - Chi-Hua Chiu
- Department of Biological Sciences, Kent State University, OH, USA
| | - C Sarah Cohen
- Biology Department, Romberg Tiburon Center for Environmental Studies, San Francisco State University, 3150 Paradise Drive, Tiburon, CA, 94920, USA
| | | | - Scott F Gilbert
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania 19081, USA and Biotechnology Institute, University of Helsinki, 00014, Helsinki, Finland
| | - Brian Hall
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, CA, B3H 4R2, USA
| | - Alan C Love
- Department of Philosophy, Minnesota Center for Philosophy of Science, University of Minnesota, USA
| | - Deirdre C Lyons
- Department of Biology, Duke University, Box 90338, Durham, NC, 27708, USA
| | - Thomas J Sanger
- Department of Molecular Genetics and Microbiology, University of Florida, P.O. Box 103610, Gainesville, FL, 32610, USA
| | - Joel Smith
- Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Chelsea Specht
- Plant and Microbial Biology, Department of Integrative Biology, University and Jepson Herbaria, University of California, Berkeley, CA, USA
| | - Mario Vallejo-Marin
- Biological and Environmental Sciences, University of Stirling, FK9 4LA, Scotland, UK
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, BioLabs 4103, Cambridge, MA, 02138, USA
| |
Collapse
|
38
|
Bundus JD, Alaei R, Cutter AD. Gametic selection, developmental trajectories, and extrinsic heterogeneity in Haldane's rule. Evolution 2015; 69:2005-17. [PMID: 26102479 DOI: 10.1111/evo.12708] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/01/2015] [Indexed: 12/31/2022]
Abstract
Deciphering the genetic and developmental causes of the disproportionate rarity, inviability, and sterility of hybrid males, Haldane's rule, is important for understanding the evolution of reproductive isolation between species. Moreover, extrinsic and prezygotic factors can contribute to the magnitude of intrinsic isolation experienced between species with partial reproductive compatibility. Here, we use the nematodes Caenorhabditis briggsae and C. nigoni to quantify the sensitivity of hybrid male viability to extrinsic temperature and developmental timing, and test for a role of mito-nuclear incompatibility as a genetic cause. We demonstrate that hybrid male inviability manifests almost entirely as embryonic, not larval, arrest and is maximal at the lowest rearing temperatures, indicating an intrinsic-by-extrinsic interaction to hybrid inviability. Crosses using mitochondrial substitution strains that have reciprocally introgressed mitochondrial and nuclear genomes show that mito-nuclear incompatibility is not a dominant contributor to postzygotic isolation and does not drive Haldane's rule in this system. Crosses also reveal that competitive superiority of X-bearing sperm provides a novel means by which postmating prezygotic factors exacerbate the rarity of hybrid males. These findings highlight the important roles of gametic, developmental, and extrinsic factors in modulating the manifestation of Haldane's rule.
Collapse
Affiliation(s)
- Joanna D Bundus
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Ravin Alaei
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2.
| |
Collapse
|
39
|
Gordon KL, Arthur RK, Ruvinsky I. Phylum-Level Conservation of Regulatory Information in Nematodes despite Extensive Non-coding Sequence Divergence. PLoS Genet 2015; 11:e1005268. [PMID: 26020930 PMCID: PMC4447282 DOI: 10.1371/journal.pgen.1005268] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 05/09/2015] [Indexed: 11/28/2022] Open
Abstract
Gene regulatory information guides development and shapes the course of evolution. To test conservation of gene regulation within the phylum Nematoda, we compared the functions of putative cis-regulatory sequences of four sets of orthologs (unc-47, unc-25, mec-3 and elt-2) from distantly-related nematode species. These species, Caenorhabditis elegans, its congeneric C. briggsae, and three parasitic species Meloidogyne hapla, Brugia malayi, and Trichinella spiralis, represent four of the five major clades in the phylum Nematoda. Despite the great phylogenetic distances sampled and the extensive sequence divergence of nematode genomes, all but one of the regulatory elements we tested are able to drive at least a subset of the expected gene expression patterns. We show that functionally conserved cis-regulatory elements have no more extended sequence similarity to their C. elegans orthologs than would be expected by chance, but they do harbor motifs that are important for proper expression of the C. elegans genes. These motifs are too short to be distinguished from the background level of sequence similarity, and while identical in sequence they are not conserved in orientation or position. Functional tests reveal that some of these motifs contribute to proper expression. Our results suggest that conserved regulatory circuitry can persist despite considerable turnover within cis elements. To explore the phylogenetic limits of conservation of cis-regulatory elements, we used transgenesis to test the functions of enhancers of four genes from several species spanning the phylum Nematoda. While we found a striking degree of functional conservation among the examined cis elements, their DNA sequences lacked apparent conservation with the C. elegans orthologs. In fact, sequence similarity between C. elegans and the distantly related nematodes was no greater than would be expected by chance. Short motifs, similar to known regulatory sequences in C. elegans, can be detected in most of the cis elements. When tested, some of these sites appear to mediate regulatory function. However, they seem to have originated through motif turnover, rather than to have been preserved from a common ancestor. Our results suggest that gene regulatory networks are broadly conserved in the phylum Nematoda, but this conservation persists despite substantial reorganization of regulatory elements and could not be detected using naïve comparisons of sequence similarity.
Collapse
Affiliation(s)
- Kacy L. Gordon
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (KLG); (IR)
| | - Robert K. Arthur
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
| | - Ilya Ruvinsky
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (KLG); (IR)
| |
Collapse
|
40
|
Abstract
The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny nematode is one of the simplest and easiest organisms to handle. And its life outside the laboratory is beginning to be unveiled. Like other model organisms, C. elegans has a boom-and-bust lifestyle. It feasts on ephemeral bacterial blooms in decomposing fruits and stems. After resource depletion, its young larvae enter a migratory diapause stage, called the dauer. Organisms known to be associated with C. elegans include migration vectors (such as snails, slugs and isopods) and pathogens (such as microsporidia, fungi, bacteria and viruses). By deepening our understanding of the natural history of C. elegans, we establish a broader context and improved tools for studying its biology.
Collapse
Affiliation(s)
- Lise Frézal
- Institute of Biology of Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Paris, France
| | - Marie-Anne Félix
- Institute of Biology of Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Paris, France
| |
Collapse
|
41
|
Thomas CG, Wang W, Jovelin R, Ghosh R, Lomasko T, Trinh Q, Kruglyak L, Stein LD, Cutter AD. Full-genome evolutionary histories of selfing, splitting, and selection in Caenorhabditis. Genome Res 2015; 25:667-78. [PMID: 25783854 PMCID: PMC4417115 DOI: 10.1101/gr.187237.114] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 03/12/2015] [Indexed: 12/19/2022]
Abstract
The nematode Caenorhabditis briggsae is a model for comparative developmental evolution with C. elegans. Worldwide collections of C. briggsae have implicated an intriguing history of divergence among genetic groups separated by latitude, or by restricted geography, that is being exploited to dissect the genetic basis to adaptive evolution and reproductive incompatibility; yet, the genomic scope and timing of population divergence is unclear. We performed high-coverage whole-genome sequencing of 37 wild isolates of the nematode C. briggsae and applied a pairwise sequentially Markovian coalescent (PSMC) model to 703 combinations of genomic haplotypes to draw inferences about population history, the genomic scope of natural selection, and to compare with 40 wild isolates of C. elegans. We estimate that a diaspora of at least six distinct C. briggsae lineages separated from one another approximately 200,000 generations ago, including the “Temperate” and “Tropical” phylogeographic groups that dominate most samples worldwide. Moreover, an ancient population split in its history approximately 2 million generations ago, coupled with only rare gene flow among lineage groups, validates this system as a model for incipient speciation. Low versus high recombination regions of the genome give distinct signatures of population size change through time, indicative of widespread effects of selection on highly linked portions of the genome owing to extreme inbreeding by self-fertilization. Analysis of functional mutations indicates that genomic context, owing to selection that acts on long linkage blocks, is a more important driver of population variation than are the functional attributes of the individually encoded genes.
Collapse
Affiliation(s)
- Cristel G Thomas
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Wei Wang
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Richard Jovelin
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Rajarshi Ghosh
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA; Department of Pediatrics-Oncology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Tatiana Lomasko
- Informatics and Bio-Computing, Ontario Institute for Cancer Research, Toronto, Ontario, Canada, M5G 0A3
| | - Quang Trinh
- Informatics and Bio-Computing, Ontario Institute for Cancer Research, Toronto, Ontario, Canada, M5G 0A3
| | - Leonid Kruglyak
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA; Departments of Human Genetics and Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, California 90095, USA; Howard Hughes Medical Institute, UCLA, Los Angeles, California 90095, USA
| | - Lincoln D Stein
- Informatics and Bio-Computing, Ontario Institute for Cancer Research, Toronto, Ontario, Canada, M5G 0A3; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 3B2; Bioinformatics and Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2; Center for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| |
Collapse
|
42
|
Antonacci S, Forand D, Wolf M, Tyus C, Barney J, Kellogg L, Simon MA, Kerr G, Wells KL, Younes S, Mortimer NT, Olesnicky EC, Killian DJ. Conserved RNA-binding proteins required for dendrite morphogenesis in Caenorhabditis elegans sensory neurons. G3 (BETHESDA, MD.) 2015; 5:639-53. [PMID: 25673135 PMCID: PMC4390579 DOI: 10.1534/g3.115.017327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/09/2015] [Indexed: 01/22/2023]
Abstract
The regulation of dendritic branching is critical for sensory reception, cell-cell communication within the nervous system, learning, memory, and behavior. Defects in dendrite morphology are associated with several neurologic disorders; thus, an understanding of the molecular mechanisms that govern dendrite morphogenesis is important. Recent investigations of dendrite morphogenesis have highlighted the importance of gene regulation at the posttranscriptional level. Because RNA-binding proteins mediate many posttranscriptional mechanisms, we decided to investigate the extent to which conserved RNA-binding proteins contribute to dendrite morphogenesis across phyla. Here we identify a core set of RNA-binding proteins that are important for dendrite morphogenesis in the PVD multidendritic sensory neuron in Caenorhabditis elegans. Homologs of each of these genes were previously identified as important in the Drosophila melanogaster dendritic arborization sensory neurons. Our results suggest that RNA processing, mRNA localization, mRNA stability, and translational control are all important mechanisms that contribute to dendrite morphogenesis, and we present a conserved set of RNA-binding proteins that regulate these processes in diverse animal species. Furthermore, homologs of these genes are expressed in the human brain, suggesting that these RNA-binding proteins are candidate regulators of dendrite development in humans.
Collapse
Affiliation(s)
- Simona Antonacci
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Daniel Forand
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918
| | - Margaret Wolf
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Courtney Tyus
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Julia Barney
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Leah Kellogg
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Margo A Simon
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Genevieve Kerr
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Kristen L Wells
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| | - Serena Younes
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918
| | - Nathan T Mortimer
- Department of Biological Sciences, University of Denver, Denver, Colorado 80208
| | - Eugenia C Olesnicky
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado 80918
| | - Darrell J Killian
- Department of Molecular Biology, Colorado College, Colorado Springs, Colorado 80903
| |
Collapse
|
43
|
Evolutionary innovation and conservation in the embryonic derivation of the vertebrate skull. Nat Commun 2014; 5:5661. [PMID: 25434971 PMCID: PMC4251486 DOI: 10.1038/ncomms6661] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 10/24/2014] [Indexed: 01/07/2023] Open
Abstract
Development of the vertebrate skull has been studied intensively for more than 150 years, yet many essential features remain unresolved. One such feature is the extent to which embryonic derivation of individual bones is evolutionarily conserved or labile. We perform long-term fate mapping using GFP-transgenic axolotl and Xenopus laevis to document the contribution of individual cranial neural crest streams to the osteocranium in these amphibians. Here we show that the axolotl pattern is strikingly similar to that in amniotes; it likely represents the ancestral condition for tetrapods. Unexpectedly, the pattern in Xenopus is much different; it may constitute a unique condition that evolved after anurans diverged from other amphibians. Such changes reveal an unappreciated relation between life history evolution and cranial development and exemplify ‘developmental system drift’, in which interspecific divergence in developmental processes that underlie homologous characters occurs with little or no concomitant change in the adult phenotype. It is unclear whether the embryonic origin of skull bones is evolutionarily conserved. Here, the authors show that the pattern of cranial development of the Mexican axolotl is similar to that reported for other vertebrates, but the pattern in the African clawed frog, another amphibian, is unique.
Collapse
|
44
|
Stolfi A, Lowe EK, Racioppi C, Ristoratore F, Brown CT, Swalla BJ, Christiaen L. Divergent mechanisms regulate conserved cardiopharyngeal development and gene expression in distantly related ascidians. eLife 2014; 3:e03728. [PMID: 25209999 PMCID: PMC4356046 DOI: 10.7554/elife.03728] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/05/2014] [Indexed: 12/13/2022] Open
Abstract
Ascidians present a striking dichotomy between conserved phenotypes and divergent genomes: embryonic cell lineages and gene expression patterns are conserved between distantly related species. Much research has focused on Ciona or Halocynthia spp. but development in other ascidians remains poorly characterized. In this study, we surveyed the multipotent myogenic B7.5 lineage in Molgula spp. Comparisons to the homologous lineage in Ciona revealed identical cell division and fate specification events that result in segregation of larval, cardiac, and pharyngeal muscle progenitors. Moreover, the expression patterns of key regulators are conserved, but cross-species transgenic assays uncovered incompatibility, or ‘unintelligibility’, of orthologous cis-regulatory sequences between Molgula and Ciona. These sequences drive identical expression patterns that are not recapitulated in cross-species assays. We show that this unintelligibility is likely due to changes in both cis- and trans-acting elements, hinting at widespread and frequent turnover of regulatory mechanisms underlying otherwise conserved aspects of ascidian embryogenesis. DOI:http://dx.doi.org/10.7554/eLife.03728.001 When two species have features that look similar, this may be because the features arise by the same processes during development. Other features may look similar yet develop by different mechanisms. ‘Developmental system drift’ refers to the process where a physical feature remains unaltered during evolution, but the underlying pathway that controls its development is changed. However, to date, there have been only a few experimental studies that support this idea. Ascidians—also commonly known as sea squirts—are vase-like marine creatures, which start off as tadpole-like larvae that swim around until they find a place to settle down and attach themselves. Once attached, the sea squirts lose the ability to swim and start feeding, typically by filtering material out of the seawater. Sea squirts and their close relatives are the invertebrates (animals without backbones) that are most closely related to all vertebrates (animals with backbones), including humans. Furthermore, although different species of sea squirt have almost identical embryos, their genomes are very different. Stolfi et al. have now studied whether developmental system drift may have occurred during the evolution of ascidians, by analyzing different species of sea squirt named Molgula and Ciona. Stolfi et al. compared the genomes of Molgula and Ciona and studied the expression of genes in the cells that give rise to the heart and the muscles of the head. As an embryo develops, specific genes are switched on or off, and these patterns of gene activation were broadly identical in the two species of sea squirt examined. Enhancers are sequences of DNA that control when and how a gene is switched on. Given the similarities between the development of heart and head muscle cells in the different sea squirts, Stolfi et al. looked to see if the mechanisms of gene expression, and therefore the enhancers, were also conserved. Unexpectedly, this was not the case. When enhancers from Molgula were introduced into Ciona (and vice versa), these sequences were unable to switch on gene expression—thus enhancers from one sea squirt species could not function in the other. Stolfi et al. conclude that the developmental systems may have drifted considerably during evolution of the sea squirts, in spite of their nearly identical embryos. This reinforces the view that different paths can lead to the formation of similar physical features. DOI:http://dx.doi.org/10.7554/eLife.03728.002
Collapse
Affiliation(s)
- Alberto Stolfi
- Center for Developmental Genetics, Department of Biology, New York University, New York, United States
| | - Elijah K Lowe
- Department of Computer Science and Engineering, Michigan State University, East Lansing, United States
| | - Claudia Racioppi
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Filomena Ristoratore
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - C Titus Brown
- Department of Computer Science and Engineering, Michigan State University, East Lansing, United States
| | - Billie J Swalla
- Department of Biology, University of Washington, Seattle, United States
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, United States
| |
Collapse
|
45
|
Abstract
Studies of X chromosome evolution in various organisms have indicated that sex-biased genes are nonrandomly distributed between the X and autosomes. Here, to extend these studies to nematodes, we annotated and analyzed X chromosome gene content in four Caenorhabditis species and in Pristionchus pacificus. Our gene expression analyses comparing young adult male and female mRNA-seq data indicate that, in general, nematode X chromosomes are enriched for genes with high female-biased expression and depleted of genes with high male-biased expression. Genes with low sex-biased expression do not show the same trend of X chromosome enrichment and depletion. Combined with the observation that highly sex-biased genes are primarily expressed in the gonad, differential distribution of sex-biased genes reflects differences in evolutionary pressures linked to tissue-specific regulation of X chromosome transcription. Our data also indicate that X dosage imbalance between males (XO) and females (XX) is influential in shaping both expression and gene content of the X chromosome. Predicted upregulation of the single male X to match autosomal transcription (Ohno's hypothesis) is supported by our observation that overall transcript levels from the X and autosomes are similar for highly expressed genes. However, comparison of differentially located one-to-one orthologs between C. elegans and P. pacificus indicates lower expression of X-linked orthologs, arguing against X upregulation. These contradicting observations may be reconciled if X upregulation is not a global mechanism but instead acts locally on a subset of tissues and X-linked genes that are dosage sensitive.
Collapse
|
46
|
Affiliation(s)
- Eric S. Haag
- Department of Biology, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
| |
Collapse
|