1
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Khurana MP, Scheidwasser-Clow N, Penn MJ, Bhatt S, Duchêne DA. The Limits of the Constant-rate Birth-Death Prior for Phylogenetic Tree Topology Inference. Syst Biol 2024; 73:235-246. [PMID: 38153910 PMCID: PMC11129600 DOI: 10.1093/sysbio/syad075] [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: 02/06/2023] [Revised: 12/20/2023] [Accepted: 12/27/2023] [Indexed: 12/30/2023] Open
Abstract
Birth-death models are stochastic processes describing speciation and extinction through time and across taxa and are widely used in biology for inference of evolutionary timescales. Previous research has highlighted how the expected trees under the constant-rate birth-death (crBD) model tend to differ from empirical trees, for example, with respect to the amount of phylogenetic imbalance. However, our understanding of how trees differ between the crBD model and the signal in empirical data remains incomplete. In this Point of View, we aim to expose the degree to which the crBD model differs from empirically inferred phylogenies and test the limits of the model in practice. Using a wide range of topology indices to compare crBD expectations against a comprehensive dataset of 1189 empirically estimated trees, we confirm that crBD model trees frequently differ topologically compared with empirical trees. To place this in the context of standard practice in the field, we conducted a meta-analysis for a subset of the empirical studies. When comparing studies that used Bayesian methods and crBD priors with those that used other non-crBD priors and non-Bayesian methods (i.e., maximum likelihood methods), we do not find any significant differences in tree topology inferences. To scrutinize this finding for the case of highly imbalanced trees, we selected the 100 trees with the greatest imbalance from our dataset, simulated sequence data for these tree topologies under various evolutionary rates, and re-inferred the trees under maximum likelihood and using the crBD model in a Bayesian setting. We find that when the substitution rate is low, the crBD prior results in overly balanced trees, but the tendency is negligible when substitution rates are sufficiently high. Overall, our findings demonstrate the general robustness of crBD priors across a broad range of phylogenetic inference scenarios but also highlight that empirically observed phylogenetic imbalance is highly improbable under the crBD model, leading to systematic bias in data sets with limited information content.
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Affiliation(s)
- Mark P Khurana
- Section of Epidemiology, Department of Public Health, University of Copenhagen, 1352 Copenhagen, Denmark
| | - Neil Scheidwasser-Clow
- Section of Epidemiology, Department of Public Health, University of Copenhagen, 1352 Copenhagen, Denmark
| | - Matthew J Penn
- Department of Statistics, University of Oxford, OX1 3LB, Oxford, UK
| | - Samir Bhatt
- Section of Epidemiology, Department of Public Health, University of Copenhagen, 1352 Copenhagen, Denmark
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, SW7 2AZ, London, UK
| | - David A Duchêne
- Centre for Evolutionary Hologenomics, University of Copenhagen, 1352 Copenhagen, Denmark
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2
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Duchêne DA, Mather N, Van Der Wal C, Ho SYW. Excluding loci with substitution saturation improves inferences from phylogenomic data. Syst Biol 2021; 71:676-689. [PMID: 34508605 PMCID: PMC9016599 DOI: 10.1093/sysbio/syab075] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 09/07/2021] [Indexed: 11/21/2022] Open
Abstract
The historical signal in nucleotide sequences becomes eroded over time by substitutions occurring repeatedly at the same sites. This phenomenon, known as substitution saturation, is recognized as one of the primary obstacles to deep-time phylogenetic inference using genome-scale data sets. We present a new test of substitution saturation and demonstrate its performance in simulated and empirical data. For some of the 36 empirical phylogenomic data sets that we examined, we detect substitution saturation in around 50% of loci. We found that saturation tends to be flagged as problematic in loci with highly discordant phylogenetic signals across sites. Within each data set, the loci with smaller numbers of informative sites are more likely to be flagged as containing problematic levels of saturation. The entropy saturation test proposed here is sensitive to high evolutionary rates relative to the evolutionary timeframe, while also being sensitive to several factors known to mislead phylogenetic inference, including short internal branches relative to external branches, short nucleotide sequences, and tree imbalance. Our study demonstrates that excluding loci with substitution saturation can be an effective means of mitigating the negative impact of multiple substitutions on phylogenetic inferences. [Phylogenetic model performance; phylogenomics; substitution model; substitution saturation; test statistics.]
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Affiliation(s)
- David A Duchêne
- Centre for Evolutionary Hologenomics, University of Copenhagen, 1352 Copenhagen, Denmark
| | - Niklas Mather
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Cara Van Der Wal
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Simon Y W Ho
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
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3
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Seo TK, Gascuel O, Thorne JL. Measuring Phylogenetic Information of Incomplete Sequence Data. Syst Biol 2021; 71:630-648. [PMID: 34469581 DOI: 10.1093/sysbio/syab073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
Widely used approaches for extracting phylogenetic information from aligned sets of molecular sequences rely upon probabilistic models of nucleotide substitution or amino-acid replacement. The phylogenetic information that can be extracted depends on the number of columns in the sequence alignment and will be decreased when the alignment contains gaps due to insertion or deletion events. Motivated by the measurement of information loss, we suggest assessment of the Effective Sequence Length (ESL) of an aligned data set. The ESL can differ from the actual number of columns in a sequence alignment because of the presence of alignment gaps. Furthermore, the estimation of phylogenetic information is affected by model misspecification. Inevitably, the actual process of molecular evolution differs from the probabilistic models employed to describe this process. This disparity means the amount of phylogenetic information in an actual sequence alignment will differ from the amount in a simulated data set of equal size, which motivated us to develop a new test for model adequacy. Via theory and empirical data analysis, we show how to disentangle the effects of gaps and model misspecification. By comparing the Fisher information of actual and simulated sequences, we identify which alignment sites and tree branches are most affected by gaps and model misspecification.
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Affiliation(s)
- Tae-Kun Seo
- Department of Biological Sciences, Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, Republic of Korea.,Unit Bioinformatique Evolutive, C3BI USR 3756, Institut Pasteur and CNRS, Paris, France [Sabbatical affiliation of T-K S]
| | - Olivier Gascuel
- Unit Bioinformatique Evolutive, C3BI USR 3756, Institut Pasteur and CNRS, Paris, France [Sabbatical affiliation of T-K S].,Institut de Systmatique, Evolution Biodiversit, (ISYEB - UMR 7205, CNRS, Musum National d'Histoire Naturel, SU, EPHE, UA), Paris, France [Current affiliation of O.G.]
| | - Jeffrey L Thorne
- Departments of Biological Sciences and Statistics, North Carolina State University, Raleigh NC 27695-7566 U.S.A
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4
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Vankan M, Ho SYW, Duchêne DA. Evolutionary Rate Variation Among Lineages in Gene Trees has a Negative Impact on Species-Tree Inference. Syst Biol 2021; 71:490-500. [PMID: 34255084 PMCID: PMC8830059 DOI: 10.1093/sysbio/syab051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/18/2021] [Indexed: 11/12/2022] Open
Abstract
Phylogenetic analyses of genomic data provide a powerful means of reconstructing the evolutionary relationships among organisms, yet such analyses are often hindered by conflicting phylogenetic signals among loci. Identifying the signals that are most influential to species-tree estimation can help to inform the choice of data for phylogenomic analysis. We investigated this in an analysis of 30 phylogenomic data sets. For each data set, we examined the association between several branch-length characteristics of gene trees and the distance between these gene trees and the corresponding species trees. We found that the distance of each gene tree to the species tree inferred from the full data set was positively associated with variation in root-to-tip distances and negatively associated with mean branch support. However, no such associations were found for gene-tree length, a measure of the overall substitution rate at each locus. We further explored the usefulness of the best-performing branch-based characteristics for selecting loci for phylogenomic analyses. We found that loci that yield gene trees with high variation in root-to-tip distances have a disproportionately distant signal of tree topology compared with the complete data sets. These results suggest that rate variation across lineages should be taken into consideration when exploring and even selecting loci for phylogenomic analysis.[Branch support; data filtering; nucleotide substitution model; phylogenomics; substitution rate; summary coalescent methods.]
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Affiliation(s)
- Mezzalina Vankan
- School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia.,Research School of Biology, Australian National University, ACT 2601, Australia
| | - Simon Y W Ho
- School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia
| | - David A Duchêne
- Research School of Biology, Australian National University, ACT 2601, Australia.,Centre for Evolutionary Hologenomics, University of Copenhagen, Copenhagen 1352, Denmark
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Kulkarni S, Kallal RJ, Wood H, Dimitrov D, Giribet G, Hormiga G. Interrogating Genomic-Scale Data to Resolve Recalcitrant Nodes in the Spider Tree of Life. Mol Biol Evol 2021; 38:891-903. [PMID: 32986823 PMCID: PMC7947752 DOI: 10.1093/molbev/msaa251] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Genome-scale data sets are converging on robust, stable phylogenetic hypotheses for many lineages; however, some nodes have shown disagreement across classes of data. We use spiders (Araneae) as a system to identify the causes of incongruence in phylogenetic signal between three classes of data: exons (as in phylotranscriptomics), noncoding regions (included in ultraconserved elements [UCE] analyses), and a combination of both (as in UCE analyses). Gene orthologs, coded as amino acids and nucleotides (with and without third codon positions), were generated by querying published transcriptomes for UCEs, recovering 1,931 UCE loci (codingUCEs). We expected that congeners represented in the codingUCE and UCEs data would form clades in the presence of phylogenetic signal. Noncoding regions derived from UCE sequences were recovered to test the stability of relationships. Phylogenetic relationships resulting from all analyses were largely congruent. All nucleotide data sets from transcriptomes, UCEs, or a combination of both recovered similar topologies in contrast with results from transcriptomes analyzed as amino acids. Most relationships inferred from low-occupancy data sets, containing several hundreds of loci, were congruent across Araneae, as opposed to high occupancy data matrices with fewer loci, which showed more variation. Furthermore, we found that low-occupancy data sets analyzed as nucleotides (as is typical of UCE data sets) can result in more congruent relationships than high occupancy data sets analyzed as amino acids (as in phylotranscriptomics). Thus, omitting data, through amino acid translation or via retention of only high occupancy loci, may have a deleterious effect in phylogenetic reconstruction.
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Affiliation(s)
- Siddharth Kulkarni
- Department of Biological Sciences, The George Washington University, Washington, DC
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC
| | - Robert J Kallal
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC
| | - Hannah Wood
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC
| | - Dimitar Dimitrov
- Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway
| | - Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA
| | - Gustavo Hormiga
- Department of Biological Sciences, The George Washington University, Washington, DC
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Walker JF, Walker-Hale N, Vargas OM, Larson DA, Stull GW. Characterizing gene tree conflict in plastome-inferred phylogenies. PeerJ 2019; 7:e7747. [PMID: 31579615 PMCID: PMC6764362 DOI: 10.7717/peerj.7747] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/25/2019] [Indexed: 11/20/2022] Open
Abstract
Evolutionary relationships among plants have been inferred primarily using chloroplast data. To date, no study has comprehensively examined the plastome for gene tree conflict. Using a broad sampling of angiosperm plastomes, we characterize gene tree conflict among plastid genes at various time scales and explore correlates to conflict (e.g., evolutionary rate, gene length, molecule type). We uncover notable gene tree conflict against a backdrop of largely uninformative genes. We find alignment length and tree length are strong predictors of concordance, and that nucleotides outperform amino acids. Of the most commonly used markers, matK, greatly outperforms rbcL; however, the rarely used gene rpoC2 is the top-performing gene in every analysis. We find that rpoC2 reconstructs angiosperm phylogeny as well as the entire concatenated set of protein-coding chloroplast genes. Our results suggest that longer genes are superior for phylogeny reconstruction. The alleviation of some conflict through the use of nucleotides suggests that stochastic and systematic error is likely the root of most of the observed conflict, but further research on biological conflict within plastome is warranted given documented cases of heteroplasmic recombination. We suggest that researchers should filter genes for topological concordance when performing downstream comparative analyses on phylogenetic data, even when using chloroplast genomes.
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Affiliation(s)
- Joseph F. Walker
- Sainsbury Laboratory (SLCU), University of Cambridge, Cambridge, United Kingdom
| | - Nathanael Walker-Hale
- Department of Plant Sciences, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Oscar M. Vargas
- University of California, Santa Cruz, Santa Cruz, United States of America
| | - Drew A. Larson
- University of Michigan—Ann Arbor, Ann Arbor, MI, United States of America
| | - Gregory W. Stull
- Department of Botany, Smithsonian Institution, Washington, United States of America
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7
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Abstract
It has long been appreciated that analyses of genomic data (e.g., whole genome sequencing or sequence capture) have the potential to reveal the tree of life, but it remains challenging to move from sequence data to a clear understanding of evolutionary history, in part due to the computational challenges of phylogenetic estimation using genome-scale data. Supertree methods solve that challenge because they facilitate a divide-and-conquer approach for large-scale phylogeny inference by integrating smaller subtrees in a computationally efficient manner. Here, we combined information from sequence capture and whole-genome phylogenies using supertree methods. However, the available phylogenomic trees had limited overlap so we used taxon-rich (but not phylogenomic) megaphylogenies to weave them together. This allowed us to construct a phylogenomic supertree, with support values, that included 707 bird species (~7% of avian species diversity). We estimated branch lengths using mitochondrial sequence data and we used these branch lengths to estimate divergence times. Our time-calibrated supertree supports radiation of all three major avian clades (Palaeognathae, Galloanseres, and Neoaves) near the Cretaceous-Paleogene (K-Pg) boundary. The approach we used will permit the continued addition of taxa to this supertree as new phylogenomic data are published, and it could be applied to other taxa as well.
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8
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Six Impossible Things before Breakfast: Assumptions, Models, and Belief in Molecular Dating. Trends Ecol Evol 2019; 34:474-486. [PMID: 30904189 DOI: 10.1016/j.tree.2019.01.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 01/16/2023]
Abstract
Confidence in molecular dating analyses has grown with the increasing sophistication of the methods. Some problematic cases where molecular dates disagreed with paleontological estimates appear to have been resolved with a growing agreement between molecules and fossils. But we cannot relax just yet. The growing analytical sophistication of many molecular dating methods relies on an increasingly large number of assumptions about evolutionary history and processes. Many of these assumptions are based on statistical tractability rather than being informed by improved understanding of molecular evolution, yet changing the assumptions can influence molecular dates. How can we tell if the answers we get are driven more by the assumptions we make than by the molecular data being analyzed?
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9
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Walker JF, Walker-Hale N, Vargas OM, Larson DA, Stull GW. Characterizing gene tree conflict in plastome-inferred phylogenies. PeerJ 2019. [PMID: 31579615 DOI: 10.1101/512079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
Evolutionary relationships among plants have been inferred primarily using chloroplast data. To date, no study has comprehensively examined the plastome for gene tree conflict. Using a broad sampling of angiosperm plastomes, we characterize gene tree conflict among plastid genes at various time scales and explore correlates to conflict (e.g., evolutionary rate, gene length, molecule type). We uncover notable gene tree conflict against a backdrop of largely uninformative genes. We find alignment length and tree length are strong predictors of concordance, and that nucleotides outperform amino acids. Of the most commonly used markers, matK, greatly outperforms rbcL; however, the rarely used gene rpoC2 is the top-performing gene in every analysis. We find that rpoC2 reconstructs angiosperm phylogeny as well as the entire concatenated set of protein-coding chloroplast genes. Our results suggest that longer genes are superior for phylogeny reconstruction. The alleviation of some conflict through the use of nucleotides suggests that stochastic and systematic error is likely the root of most of the observed conflict, but further research on biological conflict within plastome is warranted given documented cases of heteroplasmic recombination. We suggest that researchers should filter genes for topological concordance when performing downstream comparative analyses on phylogenetic data, even when using chloroplast genomes.
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Affiliation(s)
- Joseph F Walker
- Sainsbury Laboratory (SLCU), University of Cambridge, Cambridge, United Kingdom
| | - Nathanael Walker-Hale
- Department of Plant Sciences, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Oscar M Vargas
- University of California, Santa Cruz, Santa Cruz, United States of America
| | - Drew A Larson
- University of Michigan-Ann Arbor, Ann Arbor, MI, United States of America
| | - Gregory W Stull
- Department of Botany, Smithsonian Institution, Washington, United States of America
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