The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Eugene V Koonin - One of the best experts on this subject based on the ideXlab platform.
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Homoplasy in genome-wide analysis of rare amino acid replacements: the molecular-evolutionary basis for Vavilov's law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected. Results We provide a direct estimate of the level of homoplasy caused by parallel changes and reversals among the RGC_CAMs using 462 alignments of orthologous genes from 19 eukaryotic species. It is shown that the impact of parallel changes and reversals on the results of phylogenetic inference using RGC_CAMs cannot explain the observed support for the Coelomata clade. In contrast, the evidence in support of the Ecdysozoa clade, in large part, can be attributed to parallel changes. It is demonstrated that parallel changes are significantly more common in internal branches of different subtrees that are separated from the respective common ancestor by relatively short times than in terminal branches separated by longer time intervals. A similar but much weaker trend was detected for reversals. The observed evolutionary trend of parallel changes is explained in terms of the covarion model of molecular evolution. As the overlap between the covarion sets in orthologous genes from different lineages decreases with time after divergence, the likelihood of parallel changes decreases as well. Conclusion The level of homoplasy observed here appears to be low enough to justify the utility of RGC_CAMs and other types of RGCs for resolution of hard problems in phylogeny. Parallel changes, one of the major classes of events leading to homoplasy, occur much more often in relatively recently diverged lineages than in those separated from their last common ancestor by longer time intervals of time. This pattern seems to provide the molecular-evolutionary underpinning of Vavilov's law of homologous series and is readily interpreted within the framework of the covarion model of molecular evolution. Reviewers This article was reviewed by Alex Kondrashov, Nicolas Galtier, and Maximilian Telford and Robert Lanfear (nominated by Laurence Hurst).
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homoplasy in genome wide analysis of rare amino acid replacements the molecular evolutionary basis for vavilov s law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected.
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analysis of rare amino acid replacements supports the Coelomata clade
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:The recent analysis of a novel class of rare genomic changes, RGC_CAMs (after conserved amino acids-multiple substitutions), supported the Coelomata clade of animals as opposed to the Ecdysozoa clade (Rogozin et al. 2007). A subsequent reanalysis, with the sequences from the sea anemone Nematostella vectensis included in the set of outgroup species, suggested that this result was an artifact caused by reverse amino replacements and claimed support for Ecdysozoa (Irimia et al. 2007). We show that the internal branch connecting the sea anemone to the bilaterian animals is extremely short, resulting in a weak statistical support for the Coelomata clade. Direct estimation of the level of homoplasy, combined with taxon sampling with different sets of outgroup species, reinforces the support for Coelomata, whereas the effect of reversals is shown to be relatively minor.
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support for the Coelomata clade of animals from a rigorous analysis of the pattern of intron conservation
Molecular Biology and Evolution, 2007Co-Authors: Jie Zheng, Igor B Rogozin, Eugene V Koonin, Teresa M PrzytyckaAbstract:Many intron positions are conserved in varying subsets of eukaryotic genomes and, consequently, comprise a potentially informative class of phylogenetic characters. Roy and Gilbert developed a method of phylogenetic reconstruction using the patterns of intron presence-absence in eukaryotic genes and, applying this method to the analysis of animal phylogeny, obtained support for an Ecdysozoa clade (Roy SW, Gilbert W. 2005. Resolution of a deep animal divergence by the pattern of intron conservation. Proc Natl Acad Sci USA. 102:4403-4408). The critical assumption in the method was the independence of intron loss in different branches of the phylogenetic tree. Here, this assumption is refuted by showing that the branch-specific intron loss rates are strongly correlated. We show that different tree topologies are obtained, in each case with a significant statistical support, when different subsets of intron positions are analyzed. The analysis of the conserved intron positions supports the Coelomata topology, that is, a clade comprised of arthropods and chordates, whereas the analysis of more variable intron positions favors the Ecdysozoa topology, that is, a clade of arthropods and nematodes. We show, however, that the support for Ecdysozoa is fully explained by parallel loss of introns in nematodes and arthropods, a factor that does not contribute to the analysis of the conserved introns. The developed procedure for the identification and analysis of conserved introns and other characters with minimal or no homoplasy is expected to be useful for resolving many hard phylogenetic problems.
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a rigorous analysis of the pattern of intron conservation supports the Coelomata clade of animals
Research in Computational Molecular Biology, 2007Co-Authors: Jie Zheng, Igor B Rogozin, Eugene V Koonin, Teresa M PrzytyckaAbstract:Many intron positions are conserved in varying subsets of eukaryotic genomes and, consequently, comprise a potentially informative class of phylogenetic characters. Roy and Gilbert developed a method of phylogenetic reconstruction using the patterns of intron presence-absence in eukaryotic genes and, applying this method to the analysis of animal phylogeny, obtained support for an Ecdysozoa clade ([1]). The critical assumption in the method was the independence of the rates of intron loss in different branches of the phylogenetic. Here, this assumption is refuted by showing that the branch-specific intron loss rates are strongly correlated. We show that different tree topologies are obtained, in each case with a significant statistical support, when different subsets of intron positions are analyzed. The analysis of the conserved intron positions supports the Coelomata topology, i.e., a clade comprised of arthropods and chordates, whereas the analysis of more variable intron positions favors the Ecdysozoa topology, i.e., a clade of arthropods and nematodes. We show, however, that the support for Ecdysozoa is fully explained by parallel loss of introns in nematodes and arthropods, a factor that does not contribute to the analysis of the conserved introns. The developed procedure for the identification and analysis of conserved introns and other characters with minimal or no homoplasy is expected to be useful for resolving many hard phylogenetic problems.
Igor B Rogozin - One of the best experts on this subject based on the ideXlab platform.
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Homoplasy in genome-wide analysis of rare amino acid replacements: the molecular-evolutionary basis for Vavilov's law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected. Results We provide a direct estimate of the level of homoplasy caused by parallel changes and reversals among the RGC_CAMs using 462 alignments of orthologous genes from 19 eukaryotic species. It is shown that the impact of parallel changes and reversals on the results of phylogenetic inference using RGC_CAMs cannot explain the observed support for the Coelomata clade. In contrast, the evidence in support of the Ecdysozoa clade, in large part, can be attributed to parallel changes. It is demonstrated that parallel changes are significantly more common in internal branches of different subtrees that are separated from the respective common ancestor by relatively short times than in terminal branches separated by longer time intervals. A similar but much weaker trend was detected for reversals. The observed evolutionary trend of parallel changes is explained in terms of the covarion model of molecular evolution. As the overlap between the covarion sets in orthologous genes from different lineages decreases with time after divergence, the likelihood of parallel changes decreases as well. Conclusion The level of homoplasy observed here appears to be low enough to justify the utility of RGC_CAMs and other types of RGCs for resolution of hard problems in phylogeny. Parallel changes, one of the major classes of events leading to homoplasy, occur much more often in relatively recently diverged lineages than in those separated from their last common ancestor by longer time intervals of time. This pattern seems to provide the molecular-evolutionary underpinning of Vavilov's law of homologous series and is readily interpreted within the framework of the covarion model of molecular evolution. Reviewers This article was reviewed by Alex Kondrashov, Nicolas Galtier, and Maximilian Telford and Robert Lanfear (nominated by Laurence Hurst).
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homoplasy in genome wide analysis of rare amino acid replacements the molecular evolutionary basis for vavilov s law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected.
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analysis of rare amino acid replacements supports the Coelomata clade
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:The recent analysis of a novel class of rare genomic changes, RGC_CAMs (after conserved amino acids-multiple substitutions), supported the Coelomata clade of animals as opposed to the Ecdysozoa clade (Rogozin et al. 2007). A subsequent reanalysis, with the sequences from the sea anemone Nematostella vectensis included in the set of outgroup species, suggested that this result was an artifact caused by reverse amino replacements and claimed support for Ecdysozoa (Irimia et al. 2007). We show that the internal branch connecting the sea anemone to the bilaterian animals is extremely short, resulting in a weak statistical support for the Coelomata clade. Direct estimation of the level of homoplasy, combined with taxon sampling with different sets of outgroup species, reinforces the support for Coelomata, whereas the effect of reversals is shown to be relatively minor.
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support for the Coelomata clade of animals from a rigorous analysis of the pattern of intron conservation
Molecular Biology and Evolution, 2007Co-Authors: Jie Zheng, Igor B Rogozin, Eugene V Koonin, Teresa M PrzytyckaAbstract:Many intron positions are conserved in varying subsets of eukaryotic genomes and, consequently, comprise a potentially informative class of phylogenetic characters. Roy and Gilbert developed a method of phylogenetic reconstruction using the patterns of intron presence-absence in eukaryotic genes and, applying this method to the analysis of animal phylogeny, obtained support for an Ecdysozoa clade (Roy SW, Gilbert W. 2005. Resolution of a deep animal divergence by the pattern of intron conservation. Proc Natl Acad Sci USA. 102:4403-4408). The critical assumption in the method was the independence of intron loss in different branches of the phylogenetic tree. Here, this assumption is refuted by showing that the branch-specific intron loss rates are strongly correlated. We show that different tree topologies are obtained, in each case with a significant statistical support, when different subsets of intron positions are analyzed. The analysis of the conserved intron positions supports the Coelomata topology, that is, a clade comprised of arthropods and chordates, whereas the analysis of more variable intron positions favors the Ecdysozoa topology, that is, a clade of arthropods and nematodes. We show, however, that the support for Ecdysozoa is fully explained by parallel loss of introns in nematodes and arthropods, a factor that does not contribute to the analysis of the conserved introns. The developed procedure for the identification and analysis of conserved introns and other characters with minimal or no homoplasy is expected to be useful for resolving many hard phylogenetic problems.
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a rigorous analysis of the pattern of intron conservation supports the Coelomata clade of animals
Research in Computational Molecular Biology, 2007Co-Authors: Jie Zheng, Igor B Rogozin, Eugene V Koonin, Teresa M PrzytyckaAbstract:Many intron positions are conserved in varying subsets of eukaryotic genomes and, consequently, comprise a potentially informative class of phylogenetic characters. Roy and Gilbert developed a method of phylogenetic reconstruction using the patterns of intron presence-absence in eukaryotic genes and, applying this method to the analysis of animal phylogeny, obtained support for an Ecdysozoa clade ([1]). The critical assumption in the method was the independence of the rates of intron loss in different branches of the phylogenetic. Here, this assumption is refuted by showing that the branch-specific intron loss rates are strongly correlated. We show that different tree topologies are obtained, in each case with a significant statistical support, when different subsets of intron positions are analyzed. The analysis of the conserved intron positions supports the Coelomata topology, i.e., a clade comprised of arthropods and chordates, whereas the analysis of more variable intron positions favors the Ecdysozoa topology, i.e., a clade of arthropods and nematodes. We show, however, that the support for Ecdysozoa is fully explained by parallel loss of introns in nematodes and arthropods, a factor that does not contribute to the analysis of the conserved introns. The developed procedure for the identification and analysis of conserved introns and other characters with minimal or no homoplasy is expected to be useful for resolving many hard phylogenetic problems.
Liran Carmel - One of the best experts on this subject based on the ideXlab platform.
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Homoplasy in genome-wide analysis of rare amino acid replacements: the molecular-evolutionary basis for Vavilov's law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected. Results We provide a direct estimate of the level of homoplasy caused by parallel changes and reversals among the RGC_CAMs using 462 alignments of orthologous genes from 19 eukaryotic species. It is shown that the impact of parallel changes and reversals on the results of phylogenetic inference using RGC_CAMs cannot explain the observed support for the Coelomata clade. In contrast, the evidence in support of the Ecdysozoa clade, in large part, can be attributed to parallel changes. It is demonstrated that parallel changes are significantly more common in internal branches of different subtrees that are separated from the respective common ancestor by relatively short times than in terminal branches separated by longer time intervals. A similar but much weaker trend was detected for reversals. The observed evolutionary trend of parallel changes is explained in terms of the covarion model of molecular evolution. As the overlap between the covarion sets in orthologous genes from different lineages decreases with time after divergence, the likelihood of parallel changes decreases as well. Conclusion The level of homoplasy observed here appears to be low enough to justify the utility of RGC_CAMs and other types of RGCs for resolution of hard problems in phylogeny. Parallel changes, one of the major classes of events leading to homoplasy, occur much more often in relatively recently diverged lineages than in those separated from their last common ancestor by longer time intervals of time. This pattern seems to provide the molecular-evolutionary underpinning of Vavilov's law of homologous series and is readily interpreted within the framework of the covarion model of molecular evolution. Reviewers This article was reviewed by Alex Kondrashov, Nicolas Galtier, and Maximilian Telford and Robert Lanfear (nominated by Laurence Hurst).
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homoplasy in genome wide analysis of rare amino acid replacements the molecular evolutionary basis for vavilov s law of homologous series
Biology Direct, 2008Co-Authors: Igor B Rogozin, Liran Carmel, Karen Thomson, Miklós Csürös, Eugene V KooninAbstract:Background Rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are becoming an increasingly important class of markers in genome-wide phylogenetic studies. Recently, we proposed a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions) that were inferred using genome-wide identification of amino acid replacements that were: i) located in unambiguously aligned regions of orthologous genes, ii) shared by two or more taxa in positions that contain a different, conserved amino acid in a much broader range of taxa, and iii) require two or three nucleotide substitutions. When applied to animal phylogeny, the RGC_CAM approach supported the coelomate clade that unites deuterostomes with arthropods as opposed to the ecdysozoan (molting animals) clade. However, a non-negligible level of homoplasy was detected.
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analysis of rare amino acid replacements supports the Coelomata clade
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:The recent analysis of a novel class of rare genomic changes, RGC_CAMs (after conserved amino acids-multiple substitutions), supported the Coelomata clade of animals as opposed to the Ecdysozoa clade (Rogozin et al. 2007). A subsequent reanalysis, with the sequences from the sea anemone Nematostella vectensis included in the set of outgroup species, suggested that this result was an artifact caused by reverse amino replacements and claimed support for Ecdysozoa (Irimia et al. 2007). We show that the internal branch connecting the sea anemone to the bilaterian animals is extremely short, resulting in a weak statistical support for the Coelomata clade. Direct estimation of the level of homoplasy, combined with taxon sampling with different sets of outgroup species, reinforces the support for Coelomata, whereas the effect of reversals is shown to be relatively minor.
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Ecdysozoan clade rejected by genome-wide analysis of rare amino acid replacements
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:As the number of sequenced genomes from diverse walks of life rapidly increases, phylogenetic analysis is entering a new era: reconstruction of the evolutionary history of organisms on the basis of full-scale comparison of their genomes. In addition to brute force, genome-wide analysis of alignments, rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are increasingly used in genome-wide phylogenetic studies. We propose a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions), which are inferred using a genome-scale analysis of protein and underlying nucleotide sequence alignments. The RGC_CAM approach utilizes amino acid residues conserved in major eukaryotic lineages, with the exception of a few species comprising a putative clade, and selects for phylogenetic inference only those amino acid replacements that require 2 or 3 nucleotide substitutions, in order to reduce homoplasy. The RGC_CAM analysis was combined with a procedure for rigorous statistical testing of competing phylogenetic hypotheses. The RGC_CAM method is shown to be robust to branch length differences and taxon sampling. When applied to animal phylogeny, the RGC_CAM approach strongly supports the coelomate clade that unites chordates with arthropods as opposed to the ecdysozoan (molting animals) clade. This conclusion runs against the view of animal evolution that is currently prevailing in the evo-devo community. The final solution to the coelomate-ecdysozoa controversy will require a much larger set of complete genome sequences representing diverse animal taxa. It is expected that RGC_CAM and other RGC-based methods will be crucial for these future, definitive phylogenetic studies.
Yuri I Wolf - One of the best experts on this subject based on the ideXlab platform.
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analysis of rare amino acid replacements supports the Coelomata clade
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:The recent analysis of a novel class of rare genomic changes, RGC_CAMs (after conserved amino acids-multiple substitutions), supported the Coelomata clade of animals as opposed to the Ecdysozoa clade (Rogozin et al. 2007). A subsequent reanalysis, with the sequences from the sea anemone Nematostella vectensis included in the set of outgroup species, suggested that this result was an artifact caused by reverse amino replacements and claimed support for Ecdysozoa (Irimia et al. 2007). We show that the internal branch connecting the sea anemone to the bilaterian animals is extremely short, resulting in a weak statistical support for the Coelomata clade. Direct estimation of the level of homoplasy, combined with taxon sampling with different sets of outgroup species, reinforces the support for Coelomata, whereas the effect of reversals is shown to be relatively minor.
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Ecdysozoan clade rejected by genome-wide analysis of rare amino acid replacements
Molecular Biology and Evolution, 2007Co-Authors: Igor B Rogozin, Liran Carmel, Yuri I Wolf, Eugene V KooninAbstract:As the number of sequenced genomes from diverse walks of life rapidly increases, phylogenetic analysis is entering a new era: reconstruction of the evolutionary history of organisms on the basis of full-scale comparison of their genomes. In addition to brute force, genome-wide analysis of alignments, rare genomic changes (RGCs) that are thought to comprise derived shared characters of individual clades are increasingly used in genome-wide phylogenetic studies. We propose a new type of RGCs designated RGC_CAMs (after Conserved Amino acids-Multiple substitutions), which are inferred using a genome-scale analysis of protein and underlying nucleotide sequence alignments. The RGC_CAM approach utilizes amino acid residues conserved in major eukaryotic lineages, with the exception of a few species comprising a putative clade, and selects for phylogenetic inference only those amino acid replacements that require 2 or 3 nucleotide substitutions, in order to reduce homoplasy. The RGC_CAM analysis was combined with a procedure for rigorous statistical testing of competing phylogenetic hypotheses. The RGC_CAM method is shown to be robust to branch length differences and taxon sampling. When applied to animal phylogeny, the RGC_CAM approach strongly supports the coelomate clade that unites chordates with arthropods as opposed to the ecdysozoan (molting animals) clade. This conclusion runs against the view of animal evolution that is currently prevailing in the evo-devo community. The final solution to the coelomate-ecdysozoa controversy will require a much larger set of complete genome sequences representing diverse animal taxa. It is expected that RGC_CAM and other RGC-based methods will be crucial for these future, definitive phylogenetic studies.
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Coelomata and not ecdysozoa evidence from genome wide phylogenetic analysis
Genome Research, 2003Co-Authors: Yuri I Wolf, Igor B Rogozin, Eugene V KooninAbstract:Relative positions of nematodes, arthropods, and chordates in animal phylogeny remain uncertain. The traditional tree topology joins arthropods with chordates in a coelomate clade, whereas nematodes, which lack a coelome, occupy a basal position. However, the current leading hypothesis, based on phylogenetic trees for 18S ribosomal RNA and several proteins, joins nematodes with arthropods in a clade of molting animals, Ecdysozoa. We performed a phylogenetic analysis of over 500 sets of orthologous proteins, which are represented in plants, animals, and fungi, using maximum likelihood, maximum parsimony, and distance methods. Additionally, to increase the statistical power of topology tests, the same methods were applied to concatenated alignments of subunits of eight conserved macromolecular complexes. The majority of the methods, when applied to most of the orthologous clusters, both concatenated and individual, grouped the fly with humans to the exclusion of the nematode, in support of the coelomate phylogeny. Trees were also constructed using information on insertions and deletions in orthologous proteins, combinations of domains in multidomain proteins, and presence-absence of species in clusters of orthologs. All of these approaches supported the coelomate clade and showed concordance between evolution of protein sequences and higher-level evolutionary events, such as domain fusion or gene loss.
Manuel Irimia - One of the best experts on this subject based on the ideXlab platform.
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rare genomic characters do not support Coelomata intron loss gain
Molecular Biology and Evolution, 2008Co-Authors: Manuel IrimiaAbstract:Recently, a new phylogenetic method employing intron position sharing across species was proposed and support for a Coelomate clade reported (Zheng et al. 2007. A rigorous analysis of the pattern of intron conservation supports the Coelomata clade of animals. Mol Biol Evol. 24:2583-2592.). Here, we show that the previous analysis depends on: 1) an idiosyncratic definition of "conserved" introns, 2) exclusion of all phylogenetically informative introns present in outgroups, 3) incorrect inference of change along the critical branch, and 4) lack of variation in rates across branches. The method thus seems unlikely to give accurate results. In addition, we address differences in rates of loss across intron sites, which Zheng et al. claimed invalidates our previous analysis that supported Ecdysozoa (Roy and Gilbert. 2005a. Resolution of a deep animal divergence by the pattern of intron conservation. Proc Natl Acad Sci USA. 102:4403-4408.). Instead, we show that our conclusions are likely to be robust to such concerns.
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Rare Genomic Characters Do Not Support Coelomata: RGC_CAMs
Journal of Molecular Evolution, 2008Co-Authors: Manuel IrimiaAbstract:Recently there has been a lively debate about a new class of rare genomic characters, RGC_CAMs, and their implications for deep bilaterian phylogeny. Most recently, nine bilaterian species were analyzed along with subsets of six outgroups (Rogozin et al. 2007b ), and support for a coelomate clade reported. The authors suggested that our previously reported support for an ecdysozoan clade (Irimia et al. 2007 ) reflected (i) one outgroup, Nematostella vectensis , being too closely related to bilaterians and (ii) lack of “rigorous statistical analysis.” Here, we report further studies of these characters. First, we discuss general issues of outgroup choice. Second, we point out that an argument used by Rogozin et al. against backmutation is not statistically significant. Third, we point out that the statistical method of Rogozin et al. fails to incorporate backmutations, leading to systematic placement of the long-branch taxon as the outgroup. A simple modification of the method yields very different results: 51 of 63 outgroup combinations favor Ecdysozoa, inlcuding 51 of 52 with at least eight phylogenetically informative characters, and all 19 with statistically significant signal. These results indicate that the Coelomata signal is a long-branch artifact.
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Rare Genomic Characters Do Not Support Coelomata: Intron Loss/Gain
Molecular Biology and Evolution, 2008Co-Authors: Manuel IrimiaAbstract:Recently, a new phylogenetic method employing intron position sharing across species was proposed and support for a Coelomate clade reported (Zheng et al. 2007. A rigorous analysis of the pattern of intron conservation supports the Coelomata clade of animals. Mol Biol Evol. 24:2583-2592.). Here, we show that the previous analysis depends on: 1) an idiosyncratic definition of "conserved" introns, 2) exclusion of all phylogenetically informative introns present in outgroups, 3) incorrect inference of change along the critical branch, and 4) lack of variation in rates across branches. The method thus seems unlikely to give accurate results. In addition, we address differences in rates of loss across intron sites, which Zheng et al. claimed invalidates our previous analysis that supported Ecdysozoa (Roy and Gilbert. 2005a. Resolution of a deep animal divergence by the pattern of intron conservation. Proc Natl Acad Sci USA. 102:4403-4408.). Instead, we show that our conclusions are likely to be robust to such concerns.
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rare coding sequence changes are consistent with ecdysozoa not Coelomata
Molecular Biology and Evolution, 2007Co-Authors: Manuel Irimia, Ignacio Maeso, David Penny, Jordi GarciafernandezAbstract:: There is growing interest in the use of alternative, more slowly-evolving RGCs (rare genomic changes). Recently, Rogozin and coauthors (Rogozin et al. 2007) proposed a novel phylogenetic method employing rare amino acid changes, RGC-CAMs (rare genomic changes-conserved amino acids-multiple substitutions). They applied their method to 694 sets of eukaryotic orthologs in order to distinguish the relationship between nematodes, arthropods and deuterostomes. They concluded that such rare amino acid changes were consistent with the Coelomata hypothesis, which groups arthropods and deuterostomes to the exclusion of nematodes. Here we use newly available genomic sequences from Nematostella vectensis, a basal metazoan, and from Brugia malayi, an additional nematode. We show that the apparent support for Coelomata is likely to be the result of the rapid rate of evolution leading to Caenorhabditis nematodes. Including the additional species paints a very different picture, with 13 remaining characters consistent with Ecdysozoa versus only 1 consistent with Coelomata.