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Ramos E, Selleghin-Veiga G, Magpali L, Daros B, Silva F, Picorelli A, Freitas L, Nery MF. Molecular Footprints on Osmoregulation-Related Genes Associated with Freshwater Colonization by Cetaceans and Sirenians. J Mol Evol 2023; 91:865-881. [PMID: 38010516 DOI: 10.1007/s00239-023-10141-0] [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: 02/04/2023] [Accepted: 10/29/2023] [Indexed: 11/29/2023]
Abstract
The genetic basis underlying adaptive physiological mechanisms has been extensively explored in mammals after colonizing the seas. However, independent lineages of aquatic mammals exhibit complex patterns of secondary colonization in freshwater environments. This change in habitat represents new osmotic challenges, and additional changes in key systems, such as the osmoregulatory system, are expected. Here, we studied the selective regime on coding and regulatory regions of 20 genes related to the osmoregulation system in strict aquatic mammals from independent evolutionary lineages, cetaceans, and sirenians, with representatives in marine and freshwater aquatic environments. We identified positive selection signals in genes encoding the protein vasopressin (AVP) in mammalian lineages with secondary colonization in the fluvial environment and in aquaporins for lineages inhabiting the marine and fluvial environments. A greater number of sites with positive selection signals were found for the dolphin species compared to the Amazonian manatee. Only the AQP5 and AVP genes showed selection signals in more than one independent lineage of these mammals. Furthermore, the vasopressin gene tree indicates greater similarity in river dolphin sequences despite the independence of their lineages based on the species tree. Patterns of distribution and enrichment of Transcription Factors in the promoter regions of target genes were analyzed and appear to be phylogenetically conserved among sister species. We found accelerated evolution signs in genes ACE, AQP1, AQP5, AQP7, AVP, NPP4, and NPR1 for the fluvial mammals. Together, these results allow a greater understanding of the molecular bases of the evolution of genes responsible for osmotic control in aquatic mammals.
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Affiliation(s)
- Elisa Ramos
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Giovanna Selleghin-Veiga
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Letícia Magpali
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Beatriz Daros
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Felipe Silva
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Agnello Picorelli
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Lucas Freitas
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil
| | - Mariana F Nery
- Laboratório de Genômica Evolutiva., Departamento de Genética, Evolução, Microbiologia e Imunologia, Universidade Estadual de Campinas, Cidade Universitária, Campinas, SP, 13083970, Brazil.
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Roberts WR, Ruck EC, Downey KM, Pinseel E, Alverson AJ. Resolving Marine-Freshwater Transitions by Diatoms Through a Fog of Gene Tree Discordance. Syst Biol 2023; 72:984-997. [PMID: 37335140 DOI: 10.1093/sysbio/syad038] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 06/02/2023] [Accepted: 06/16/2023] [Indexed: 06/21/2023] Open
Abstract
Despite the obstacles facing marine colonists, most lineages of aquatic organisms have colonized and diversified in freshwaters repeatedly. These transitions can trigger rapid morphological or physiological change and, on longer timescales, lead to increased rates of speciation and extinction. Diatoms are a lineage of ancestrally marine microalgae that have diversified throughout freshwater habitats worldwide. We generated a phylogenomic data set of genomes and transcriptomes for 59 diatom taxa to resolve freshwater transitions in one lineage, the Thalassiosirales. Although most parts of the species tree were consistently resolved with strong support, we had difficulties resolving a Paleocene radiation, which affected the placement of one freshwater lineage. This and other parts of the tree were characterized by high levels of gene tree discordance caused by incomplete lineage sorting and low phylogenetic signal. Despite differences in species trees inferred from concatenation versus summary methods and codons versus amino acids, traditional methods of ancestral state reconstruction supported six transitions into freshwaters, two of which led to subsequent species diversification. Evidence from gene trees, protein alignments, and diatom life history together suggest that habitat transitions were largely the product of homoplasy rather than hemiplasy, a condition where transitions occur on branches in gene trees not shared with the species tree. Nevertheless, we identified a set of putatively hemiplasious genes, many of which have been associated with shifts to low salinity, indicating that hemiplasy played a small but potentially important role in freshwater adaptation. Accounting for differences in evolutionary outcomes, in which some taxa became locked into freshwaters while others were able to return to the ocean or become salinity generalists, might help further distinguish different sources of adaptive mutation in freshwater diatoms.
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Affiliation(s)
- Wade R Roberts
- Department of Biological Sciences, University of Arkansas, 1 University of Arkansas, Fayetteville, AR, 72701, USA
| | - Elizabeth C Ruck
- Department of Biological Sciences, University of Arkansas, 1 University of Arkansas, Fayetteville, AR, 72701, USA
| | - Kala M Downey
- Department of Biological Sciences, University of Arkansas, 1 University of Arkansas, Fayetteville, AR, 72701, USA
| | - Eveline Pinseel
- Department of Biological Sciences, University of Arkansas, 1 University of Arkansas, Fayetteville, AR, 72701, USA
| | - Andrew J Alverson
- Department of Biological Sciences, University of Arkansas, 1 University of Arkansas, Fayetteville, AR, 72701, USA
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Youssef N, Susko E, Roger AJ, Bielawski JP. Evolution of amino acid propensities under stability-mediated epistasis. Mol Biol Evol 2022; 39:6522130. [PMID: 35134997 PMCID: PMC8896634 DOI: 10.1093/molbev/msac030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Site-specific amino acid preferences are influenced by the genetic background of the protein. The preferences for resident amino acids are expected to, on average, increase over time because of replacements at other sites - a nonadaptive phenomenon referred to as the 'evolutionary Stokes shift'. Alternatively, decreases in resident amino acid propensity have recently been viewed as evidence of adaptations to external environmental changes. Using population genetics theory and thermodynamic stability-constraints, we show that nonadaptive evolution can lead to both positive and negative shifts in propensities following the fixation of an amino acid, emphasizing that the detection of negative shifts is not conclusive evidence of adaptation. Considering shifts in propensities over windows between substitutions at a focal site, we find that following ≈ 50% of substitutions the propensity for the new resident amino acid decreases over time, and both positive and negative shifts were comparable in magnitude. Preferences were often conserved via a significant negative autocorrelation in propensity changes-increases in propensities often followed by decreases, and vice versa. Lastly, we explore the underlying mechanisms that lead propensities to fluctuate. We observe that stabilizing replacements increase the mutational tolerance at a site and in doing so decrease the propensity for the resident amino acid. In contrast, destabilizing substitutions result in more rugged fitness landscapes that tend to favor the resident amino acid. In summary, our results characterize propensity trajectories under nonadaptive stability-constrained evolution against which evidence of adaptations should be calibrated.
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Affiliation(s)
- Noor Youssef
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Edward Susko
- Department of Mathematics and Statistics, Dalhousie University, Halifax, NS, Canada
| | - Andrew J Roger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Joseph P Bielawski
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, Canada
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Youssef N, Susko E, Roger AJ, Bielawski JP. Shifts in amino acid preferences as proteins evolve: A synthesis of experimental and theoretical work. Protein Sci 2021; 30:2009-2028. [PMID: 34322924 PMCID: PMC8442975 DOI: 10.1002/pro.4161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 11/08/2022]
Abstract
Amino acid preferences vary across sites and time. While variation across sites is widely accepted, the extent and frequency of temporal shifts are contentious. Our understanding of the drivers of amino acid preference change is incomplete: To what extent are temporal shifts driven by adaptive versus nonadaptive evolutionary processes? We review phenomena that cause preferences to vary (e.g., evolutionary Stokes shift, contingency, and entrenchment) and clarify how they differ. To determine the extent and prevalence of shifted preferences, we review experimental and theoretical studies. Analyses of natural sequence alignments often detect decreases in homoplasy (convergence and reversions) rates, and variation in replacement rates with time-signals that are consistent with temporally changing preferences. While approaches inferring shifts in preferences from patterns in natural alignments are valuable, they are indirect since multiple mechanisms (both adaptive and nonadaptive) could lead to the observed signal. Alternatively, site-directed mutagenesis experiments allow for a more direct assessment of shifted preferences. They corroborate evidence from multiple sequence alignments, revealing that the preference for an amino acid at a site varies depending on the background sequence. However, shifts in preferences are usually minor in magnitude and sites with significantly shifted preferences are low in frequency. The small yet consistent perturbations in preferences could, nevertheless, jeopardize the accuracy of inference procedures, which assume constant preferences. We conclude by discussing if and how such shifts in preferences might influence widely used time-homogenous inference procedures and potential ways to mitigate such effects.
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Affiliation(s)
- Noor Youssef
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Edward Susko
- Department of Mathematics and StatisticsDalhousie UniversityHalifaxNova ScotiaCanada
| | - Andrew J. Roger
- Department of Biochemistry and Molecular BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Joseph P. Bielawski
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
- Department of Mathematics and StatisticsDalhousie UniversityHalifaxNova ScotiaCanada
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