Dataset Information

Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model.

ABSTRACT: The reconstruction of the Tree of Life has relied almost entirely on concatenation methods, which do not accommodate gene tree heterogeneity, a property that simulations and theory have identified as a likely cause of incongruent phylogenies. However, this incongruence has not yet been demonstrated in empirical studies. Several key relationships among eutherian mammals remain controversial and conflicting among previous studies, including the root of eutherian tree and the relationships within Euarchontoglires and Laurasiatheria. Both bayesian and maximum-likelihood analysis of genome-wide data of 447 nuclear genes from 37 species show that concatenation methods indeed yield strong incongruence in the phylogeny of eutherian mammals, as revealed by subsampling analyses of loci and taxa, which produced strongly conflicting topologies. In contrast, the coalescent methods, which accommodate gene tree heterogeneity, yield a phylogeny that is robust to variable gene and taxon sampling and is congruent with geographic data. The data also demonstrate that incomplete lineage sorting, a major source of gene tree heterogeneity, is relevant to deep-level phylogenies, such as those among eutherian mammals. Our results firmly place the eutherian root between Atlantogenata and Boreoeutheria and support ungulate polyphyly and a sister-group relationship between Scandentia and Primates. This study demonstrates that the incongruence introduced by concatenation methods is a major cause of long-standing uncertainty in the phylogeny of eutherian mammals, and the same may apply to other clades. Our analyses suggest that such incongruence can be resolved using phylogenomic data and coalescent methods that deal explicitly with gene tree heterogeneity.

SUBMITTER: Song S

PROVIDER: S-EPMC3443116 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model.

Song Sen S Liu Liang L Edwards Scott V SV Wu Shaoyuan S

Proceedings of the National Academy of Sciences of the United States of America 20120828 37

The reconstruction of the Tree of Life has relied almost entirely on concatenation methods, which do not accommodate gene tree heterogeneity, a property that simulations and theory have identified as a likely cause of incongruent phylogenies. However, this incongruence has not yet been demonstrated in empirical studies. Several key relationships among eutherian mammals remain controversial and conflicting among previous studies, including the root of eutherian tree and the relationships within E ...[more]

PMID: 22930817

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Project description:BACKGROUND:The Fusarium oxysporum species complex (FOSC) is a ubiquitous group of fungal species readily isolated from agroecosystem and natural ecosystem soils which includes important plant and human pathogens. Genetic relatedness within the complex has been studied by sequencing either the genes or the barcoding gene regions within those genes. Phylogenetic analyses have demonstrated a great deal of diversity which is reflected in the differing number of clades identified: three, five and eight. Genetic limitation within the species in the complex has been studied through Genealogical Concordance Phylogenetic Species Recognition (GCPSR) analyses with varying number of phylogenetic 'species' identified ranging from two to 21. Such differing views have continued to confuse users of these taxonomies. RESULTS:The phylogenetic relationships between Australian F. oxysporum isolates from both natural and agricultural ecosystems were determined using three datasets: whole genome, nuclear genes, and mitochondrial genome sequences. The phylogenies were concordant except for three isolates. There were three concordant clades from all the phylogenies suggesting similar evolutionary history for mitochondrial genome and nuclear genes for the isolates in these three clades. Applying a multispecies coalescent (MSC) model on the eight single copy nuclear protein coding genes from the nuclear gene dataset concluded that the three concordant clades correspond to three phylogenetic species within the FOSC. There was 100% posterior probability support for the formation of three species within the FOSC. This is the first report of using the MSC model to estimate species within the F. oxysporum species complex. The findings from this study were compared with previously published phylogenetics and species delimitation studies. CONCLUSION:Phylogenetic analyses using three different gene datasets from Australian F. oxysporum isolates have all supported the formation of three major clades which delineated into three species. Species 2 (Clade 3) may be called F. oxysporum as it contains the neotype for F. oxysporum.

Project description:A statistical framework of model comparison and model validation is essential to resolving the debates over concatenation and coalescent models in phylogenomic data analysis. A set of statistical tests are here applied and developed to evaluate and compare the adequacy of substitution, concatenation, and multispecies coalescent (MSC) models across 47 phylogenomic data sets collected across tree of life. Tests for substitution models and the concatenation assumption of topologically congruent gene trees suggest that a poor fit of substitution models, rejected by 44% of loci, and concatenation models, rejected by 38% of loci, is widespread. Logistic regression shows that the proportions of GC content and informative sites are both negatively correlated with the fit of substitution models across loci. Moreover, a substantial violation of the concatenation assumption of congruent gene trees is consistently observed across six major groups (birds, mammals, fish, insects, reptiles, and others, including other invertebrates). In contrast, among those loci adequately described by a given substitution model, the proportion of loci rejecting the MSC model is 11%, significantly lower than those rejecting the substitution and concatenation models. Although conducted on reduced data sets due to computational constraints, Bayesian model validation and comparison both strongly favor the MSC over concatenation across all data sets; the concatenation assumption of congruent gene trees rarely holds for phylogenomic data sets with more than 10 loci. Thus, for large phylogenomic data sets, model comparisons are expected to consistently and more strongly favor the coalescent model over the concatenation model. We also found that loci rejecting the MSC have little effect on species tree estimation. Our study reveals the value of model validation and comparison in phylogenomic data analysis, as well as the need for further improvements of multilocus models and computational tools for phylogenetic inference. [Bayes factor; Bayesian model validation; coalescent prior; congruent gene trees; independent prior; Metazoa; posterior predictive simulation.].

Dataset Information

Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model.

Publications

Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model.

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