Supertrees join the mainstream of phylogenetics

School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
Trends in Ecology & Evolution (Impact Factor: 16.2). 12/2008; 24(1):1-3. DOI: 10.1016/j.tree.2008.08.006
Source: PubMed


Supertree methods are fairly widely used to build comprehensive phylogenies for particular groups, but concerns remain over the adequacy of existing approaches. Steel and Rodrigo recently introduced a statistical model of incongruence between trees, allowing maximum-likelihood supertree inference. This approach to supertree construction will enable hypothesis-testing and model-choice methods that are now routine in sequence phylogenetics to be applied in this setting, and might form an important part of future phylogenetic inference from genomic data.

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Available from: James A Cotton, Apr 19, 2015
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    • "Likewise, the subtree prune-regraft (SPR) distance (Beiko and Hamilton 2006) has been used in an exponential model of phylogenetic recombination, where the penalty is against trees in adjacent alignment segments that can only be reconciled through several recombination events, as estimated by the SPR distance between them (de Oliveira Martins et al. 2008; de Oliveira Martins and Kishino 2010). Probabilistic supertree approaches like ML supertrees have a lot of potential, as they can leverage statistical sophistication with computational tractability, being able to deal with several processes of incongruence at once (Cotton and Wilkinson 2009). In this work, we further extended the ML supertree approach in several notable ways, creating a hierarchical Bayesian supertree model. "
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    ABSTRACT: Current phylogenomic data sets highlight the need for species tree methods able to deal with several sources of gene tree/species tree incongruence. At the same time, we need to make most use of all available data. Most species tree methods deal with single processes of phylogenetic discordance, namely, gene duplication and loss, incomplete lineage sorting or horizontal gene transfer. In this manuscript we address the problem of species tree inference from multilocus, genome-wide data sets regardless of the presence of gene duplication and loss and incomplete lineage sorting, therefore without the need to identify orthologs or to use a single individual per species. We do this by extending the idea of Maximum Likelihood supertrees to a hierarchical Bayesian model where several sources of gene tree/species tree disagreement can be accounted for in a modular manner. We implemented this model in a computer program called guenomu whose inputs are posterior distributions of unrooted gene tree topologies for multiple gene families, and whose output is the posterior distribution of rooted species tree topologies. We conducted extensive simulations in order to evaluate the performance of our approach in comparison with other species tree approaches able to deal with more than one leaf from the same species. Our method ranked best under simulated data sets, in spite of ignoring branch lengths, and performed well on empirical data, as well as being fast enough to analyze relatively large data sets. Our Bayesian supertree method was also very successful in obtaining better estimates of gene trees, by reducing the uncertainty in their distributions. In addition, our results show that under complex simulation scenarios, gene tree parsimony is also a competitive approach once we consider its speed, in contrast to more sophisticated models.
    Preview · Article · Oct 2014 · Systematic Biology
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    • "Supertree approaches are appealing in that they only require source trees to share some (but not all) taxa. One can immediately see its utility, particularly with large, disparate datasets of extinct and extant taxa (Cotton and Wilkinson, 2009). This approach may elevate the incorporation of multiple lines of ecological and historical evidence into a resolved phylogeny that, in turn, provides a baseline for hypothesis testing. "
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    ABSTRACT: Species are the currency of biodiversity and an accurate recognition of their status is a scientific necessity, particularly given the onset of the Anthropocene (the most recent biodiversity crisis). Yet, concept-based species approaches are contentious whereas those more deterministic work against the fluidity of speciation itself. This conceptual gap can be bridged through a comprehensive assessment of the nine subspecies comprising the historically enigmatic Western Rattlesnake (Crotalus viridis) complex, one that employs three disparate datasets. First, mitochondrial DNA (mtDNA) sequence data were used to derive a Bayesian phylogenetic hypothesis that revealed two well- supported lineages, each with subspecies as distinct clades. Second, morphological data relating to head shape were analyzed using Geometric Morphometric (GM) methodology to again reveal two distinct lineages, each composed of subspecies that differ significantly in shape, yet with confounding factors that obscure evolutionary relationships. Finally, GIS-based macroecological variables gathered from museum specimens again demonstrated significant subspecific niches, suggesting the potential for ecological speciation within the complex. The three datasets (molecular, morphological, and ecological) were coalesced using supertree methodology to derive a single hypothesis that supported two distinct lineages but with obscured subspecific relationships. They were also utilized in crosshair classification tests that quantified ‘historical’ and ‘recent’ non-exchangeability among lineages and subspecies (i.e., if these entities were distinct amongst themselves and worthy of taxonomic recognition). In this regard, sufficient genetic, ecological and morphological non-exchangeability exists between lineages and among subspecies to warrant species designations for six II of 9 Western Rattlesnake subspecies, with the remaining three retained at subspecific status. These efforts thus represent a comprehensive and contemporary perspective of Western Rattlesnake biodiversity, and shed light on a group that has proven elusive across two centuries of scientific inquiry.
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    ABSTRACT: dans lesquelles les rétrotransposons jouent un rôle moteur. Dans ce cadre, nous nous sommes fixé trois objectifs de travail : 1) améliorer notre connaissance des relations phylogénétiques au sein du genre Lupinus (Fabaceae) par l'utilisation de nouveaux marqueurs nucléaires (ARNr-ETS et SymRK), 2) évaluer par amplification et par hybridation in situ la diversité, l'abondance et le rôle des rétrotransposons Ty1/copia et Ty3/gypsy dans les variations de taille de génome des lupins, et 3) séquencer, annoter et comparer une première région génomique disponible pour un lupin avec les régions homologues d'autres fabacées. La phylogénie obtenu améliore notre compréhension de l'histoire évolutive des lupins, etmet en évidence des schémas de variation de taille de génome différents d'une lignée à l'autre. Les analyses de rétrotransposons révèlent que les éléments copia et gypsy contribuent de façon plus significative aux différences de taille de génome chez les lupins méditerranéens que chez les lupins africains et suggèrent différents modes et mécanismes d'évolution de la taille des génomes au sein du genre. À l'échelle locale (région du gène SymRK), nous confirmons la forte implication de ces éléments qui représentent 25% de la région analysée chez Lupinus angustifolius.
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