1
|
Glasenapp MR, Pogson GH. Selection Shapes the Genomic Landscape of Introgressed Ancestry in a Pair of Sympatric Sea Urchin Species. Genome Biol Evol 2024; 16:evae124. [PMID: 38874390 PMCID: PMC11212366 DOI: 10.1093/gbe/evae124] [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: 12/06/2023] [Revised: 05/10/2024] [Accepted: 06/07/2024] [Indexed: 06/15/2024] Open
Abstract
A growing number of recent studies have demonstrated that introgression is common across the tree of life. However, we still have a limited understanding of the fate and fitness consequence of introgressed variation at the whole-genome scale across diverse taxonomic groups. Here, we implemented a phylogenetic hidden Markov model to identify and characterize introgressed genomic regions in a pair of well-diverged, nonsister sea urchin species: Strongylocentrotus pallidus and Strongylocentrotus droebachiensis. Despite the old age of introgression, a sizable fraction of the genome (1% to 5%) exhibited introgressed ancestry, including numerous genes showing signals of historical positive selection that may represent cases of adaptive introgression. One striking result was the overrepresentation of hyalin genes in the identified introgressed regions despite observing considerable overall evidence of selection against introgression. There was a negative correlation between introgression and chromosome gene density, and two chromosomes were observed with considerably reduced introgression. Relative to the nonintrogressed genome-wide background, introgressed regions had significantly reduced nucleotide divergence (dXY) and overlapped fewer protein-coding genes, coding bases, and genes with a history of positive selection. Additionally, genes residing within introgressed regions showed slower rates of evolution (dN, dS, dN/dS) than random samples of genes without introgressed ancestry. Overall, our findings are consistent with widespread selection against introgressed ancestry across the genome and suggest that slowly evolving, low-divergence genomic regions are more likely to move between species and avoid negative selection following hybridization and introgression.
Collapse
Affiliation(s)
- Matthew R Glasenapp
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, USA
| | - Grant H Pogson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, USA
| |
Collapse
|
2
|
Gert KRB, Panser K, Surm J, Steinmetz BS, Schleiffer A, Jovine L, Moran Y, Kondrashov F, Pauli A. Divergent molecular signatures in fish Bouncer proteins define cross-fertilization boundaries. Nat Commun 2023; 14:3506. [PMID: 37316475 DOI: 10.1038/s41467-023-39317-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 06/05/2023] [Indexed: 06/16/2023] Open
Abstract
Molecular compatibility between gametes is a prerequisite for successful fertilization. As long as a sperm and egg can recognize and bind each other via their surface proteins, gamete fusion may occur even between members of separate species, resulting in hybrids that can impact speciation. The egg membrane protein Bouncer confers species specificity to gamete interactions between medaka and zebrafish, preventing their cross-fertilization. Here, we leverage this specificity to uncover distinct amino acid residues and N-glycosylation patterns that differentially influence the function of medaka and zebrafish Bouncer and contribute to cross-species incompatibility. Curiously, in contrast to the specificity observed for medaka and zebrafish Bouncer, seahorse and fugu Bouncer are compatible with both zebrafish and medaka sperm, in line with the pervasive purifying selection that dominates Bouncer's evolution. The Bouncer-sperm interaction is therefore the product of seemingly opposing evolutionary forces that, for some species, restrict fertilization to closely related fish, and for others, allow broad gamete compatibility that enables hybridization.
Collapse
Affiliation(s)
- Krista R B Gert
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030, Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030, Vienna, Austria
| | - Karin Panser
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030, Vienna, Austria
| | - Joachim Surm
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Benjamin S Steinmetz
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030, Vienna, Austria
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, 8093, Zürich, Switzerland
| | - Alexander Schleiffer
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030, Vienna, Austria
| | - Luca Jovine
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel
| | - Fyodor Kondrashov
- Institute of Science and Technology Austria, Klosterneuburg, Austria
- Evolutionary and Synthetic Biology Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Andrea Pauli
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Campus-Vienna-Biocenter 1, 1030, Vienna, Austria.
| |
Collapse
|
3
|
Weber AAT, Hugall AF, O’Hara TD. Convergent Evolution and Structural Adaptation to the Deep Ocean in the Protein-Folding Chaperonin CCTα. Genome Biol Evol 2020; 12:1929-1942. [PMID: 32780796 PMCID: PMC7643608 DOI: 10.1093/gbe/evaa167] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2020] [Indexed: 12/14/2022] Open
Abstract
The deep ocean is the largest biome on Earth and yet it is among the least studied environments of our planet. Life at great depths requires several specific adaptations; however, their molecular mechanisms remain understudied. We examined patterns of positive selection in 416 genes from four brittle star (Ophiuroidea) families displaying replicated events of deep-sea colonization (288 individuals from 216 species). We found consistent signatures of molecular convergence in functions related to protein biogenesis, including protein folding and translation. Five genes were recurrently positively selected, including chaperonin-containing TCP-1 subunit α (CCTα), which is essential for protein folding. Molecular convergence was detected at the functional and gene levels but not at the amino-acid level. Pressure-adapted proteins are expected to display higher stability to counteract the effects of denaturation. We thus examined in silico local protein stability of CCTα across the ophiuroid tree of life (967 individuals from 725 species) in a phylogenetically corrected context and found that deep-sea-adapted proteins display higher stability within and next to the substrate-binding region, which was confirmed by in silico global protein stability analyses. This suggests that CCTα displays not only structural but also functional adaptations to deep-water conditions. The CCT complex is involved in the folding of ∼10% of newly synthesized proteins and has previously been categorized as a "cold-shock" protein in numerous eukaryotes. We thus propose that adaptation mechanisms to cold and deep-sea environments may be linked and highlight that efficient protein biogenesis, including protein folding and translation, is a key metabolic deep-sea adaptation.
Collapse
Affiliation(s)
- Alexandra A -T Weber
- Sciences, Museums Victoria, Melbourne, Victoria, Australia
- Centre de Bretagne, REM/EEP, Ifremer, Laboratoire Environnement Profond, Plouzané, France
- Zoological Institute, University of Basel, Switzerland
| | | | | |
Collapse
|
4
|
Wang H, Zhao H, Sun K, Huang X, Jin L, Feng J. Evolutionary Basis of High-Frequency Hearing in the Cochleae of Echolocators Revealed by Comparative Genomics. Genome Biol Evol 2020; 12:3740-3753. [PMID: 31730196 PMCID: PMC7145703 DOI: 10.1093/gbe/evz250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2019] [Indexed: 12/25/2022] Open
Abstract
High-frequency hearing is important for the survival of both echolocating bats and whales, but our understanding of its genetic basis is scattered and segmented. In this study, we combined RNA-Seq and comparative genomic analyses to obtain insights into the comprehensive gene expression profile of the cochlea and the adaptive evolution of hearing-related genes. A total of 144 genes were found to have been under positive selection in various species of echolocating bats and toothed whales, 34 of which were identified to be related to hearing behavior or auditory processes. Subsequently, multiple physiological processes associated with those genes were found to have adaptively evolved in echolocating bats and toothed whales, including cochlear bony development, antioxidant activity, ion balance, and homeostatic processes, along with signal transduction. In addition, abundant convergent/parallel genes and sites were detected between different pairs of echolocator species; however, no specific hearing-related physiological pathways were enriched by them and almost all of the convergent/parallel signals were selectively neutral, as previously reported. Notably, two adaptive parallel evolved sites in TECPR2 were shown to have been under positive selection, indicating their functional importance for the evolution of echolocation and high-frequency hearing in laryngeal echolocating bats. This study deepens our understanding of the genetic bases underlying high-frequency hearing in the cochlea of echolocating bats and toothed whales.
Collapse
Affiliation(s)
- Hui Wang
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Life Science, Jilin Agricultural University, Changchun, China
| | - Hanbo Zhao
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Keping Sun
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Xiaobin Huang
- Vector Laboratory for Zoonosis Control and Prevention, Dali University, China
| | - Longru Jin
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Life Science, Jilin Agricultural University, Changchun, China
| |
Collapse
|
5
|
Morgan CC, Hart MW. Molecular evolution of mammalian genes with epistatic interactions in fertilization. BMC Evol Biol 2019; 19:154. [PMID: 31345177 PMCID: PMC6659299 DOI: 10.1186/s12862-019-1480-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/16/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Genes that encode proteins associated with sperm competition, fertilization, and sexual conflicts of interest are often among the most rapidly evolving parts of animal genomes. One family of sperm-expressed genes (Zp3r, C4bpa) in the mammalian gene cluster called the regulator of complement activation (RCA) encodes proteins that bind eggs and mediate reproductive success, and are therefore expected to show high relative rates of nonsynonymous nucleotide substitution in response to sexual selection in comparison to other genes not involved in gamete binding at fertilization. We tested that working hypothesis by using phylogenetic models of codon evolution to identify episodes of diversifying positive selection. We used a comparative approach to quantify the evidence for episodic diversifying selection acting on RCA genes with known functions in fertilization (and sensitivity to sexual selection), and contrast them with other RCA genes in the same gene family that function in innate immunity (and are not sensitive to sexual selection). RESULTS We expected but did not find evidence for more episodes of positive selection on Zp3r in Glires (the rodents and lagomorphs) or on C4BPA in Primates, in comparison to other paralogous RCA genes in the same taxon, or in comparison to the same orthologous RCA gene in the other taxon. That result was not unique to RCA genes: we also found little evidence for more episodes of diversifying selection on genes that encode selective sperm-binding molecules in the egg coat or zona pellucida (Zp2, Zp3) in comparison to members of the same gene family that encode structural elements of the egg coat (Zp1, Zp4). Similarly, we found little evidence for episodic diversifying selection acting on two other recently discovered genes (Juno, Izumo1) that encode essential molecules for sperm-egg fusion. CONCLUSIONS These negative results help to illustrate the importance of a comparative context for this type of codon model analysis. The results may also point to other phylogenetic contexts in which the effects of selection acting on these fertilization proteins might be more readily discovered and documented in mammals and other taxa.
Collapse
Affiliation(s)
- Claire C. Morgan
- Department of Medicine, Imperial College London, London, W12 0NN UK
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Michael W. Hart
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada
| |
Collapse
|
6
|
Saarman NP, Kober KM, Simison WB, Pogson GH. Sequence-Based Analysis of Thermal Adaptation and Protein Energy Landscapes in an Invasive Blue Mussel (Mytilus galloprovincialis). Genome Biol Evol 2018; 9:2739-2751. [PMID: 28985307 PMCID: PMC5647807 DOI: 10.1093/gbe/evx190] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2017] [Indexed: 12/12/2022] Open
Abstract
Adaptive responses to thermal stress in poikilotherms plays an important role in determining competitive ability and species distributions. Amino acid substitutions that affect protein stability and modify the thermal optima of orthologous proteins may be particularly important in this context. Here, we examine a set of 2,770 protein-coding genes to determine if proteins in a highly invasive heat tolerant blue mussel (Mytilus galloprovincialis) contain signals of adaptive increases in protein stability relative to orthologs in a more cold tolerant M. trossulus. Such thermal adaptations might help to explain, mechanistically, the success with which the invasive marine mussel M. galloprovincialis has displaced native species in contact zones in the eastern (California) and western (Japan) Pacific. We tested for stabilizing amino acid substitutions in warm tolerant M. galloprovincialis relative to cold tolerant M. trossulus with a generalized linear model that compares in silico estimates of recent changes in protein stability among closely related congeners. Fixed substitutions in M. galloprovincialis were 3,180.0 calories per mol per substitution more stabilizing at genes with both elevated dN/dS ratios and transcriptional responses to heat stress, and 705.8 calories per mol per substitution more stabilizing across all 2,770 loci investigated. Amino acid substitutions concentrated in a small number of genes were more stabilizing in M. galloprovincialis compared with cold tolerant M. trossulus. We also tested for, but did not find, enrichment of a priori GO terms in genes with elevated dN/dS ratios in M. galloprovincialis. This might indicate that selection for thermodynamic stability is generic across all lineages, and suggests that the high change in estimated protein stability that we observed in M. galloprovincialis is driven by selection for extra stabilizing substitutions, rather than by higher incidence of selection in a greater number of genes in this lineage. Nonetheless, our finding of more stabilizing amino acid changes in the warm adapted lineage is important because it suggests that adaption for thermal stability has contributed to M. galloprovincialis’ superior tolerance to heat stress, and that pairing tests for positive selection and tests for transcriptional response to heat stress can identify candidates of protein stability adaptation.
Collapse
Affiliation(s)
- Norah P Saarman
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz.,Department of Ecology and Evolutionary Biology, Yale University
| | - Kord M Kober
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz.,Department of Physiological Nursing, University of California, San Francisco.,Institute for Computational Health Sciences, University of California, San Francisco
| | - W Brian Simison
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, California
| | - Grant H Pogson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz
| |
Collapse
|
7
|
Buckley KM, Rast JP. An Organismal Model for Gene Regulatory Networks in the Gut-Associated Immune Response. Front Immunol 2017; 8:1297. [PMID: 29109720 PMCID: PMC5660111 DOI: 10.3389/fimmu.2017.01297] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/27/2017] [Indexed: 12/27/2022] Open
Abstract
The gut epithelium is an ancient site of complex communication between the animal immune system and the microbial world. While elements of self-non-self receptors and effector mechanisms differ greatly among animal phyla, some aspects of recognition, regulation, and response are broadly conserved. A gene regulatory network (GRN) approach provides a means to investigate the nature of this conservation and divergence even as more peripheral functional details remain incompletely understood. The sea urchin embryo is an unparalleled experimental model for detangling the GRNs that govern embryonic development. By applying this theoretical framework to the free swimming, feeding larval stage of the purple sea urchin, it is possible to delineate the conserved regulatory circuitry that regulates the gut-associated immune response. This model provides a morphologically simple system in which to efficiently unravel regulatory connections that are phylogenetically relevant to immunity in vertebrates. Here, we review the organism-wide cellular and transcriptional immune response of the sea urchin larva. A large set of transcription factors and signal systems, including epithelial expression of interleukin 17 (IL17), are important mediators in the activation of the early gut-associated response. Many of these have homologs that are active in vertebrate immunity, while others are ancient in animals but absent in vertebrates or specific to echinoderms. This larval model provides a means to experimentally characterize immune function encoded in the sea urchin genome and the regulatory interconnections that control immune response and resolution across the tissues of the organism.
Collapse
Affiliation(s)
- Katherine M Buckley
- Department of Biological Sciences, The George Washington University, Washington, DC, United States
| | - Jonathan P Rast
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.,Department of Immunology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|