Efficient algorithms for the reconciliation problem with gene duplication, horizontal transfer and loss

Motivation: Gene family evolution is driven by evolutionary events such as speciation, gene duplication, horizontal gene transfer and gene loss, and inferring these events in the evolutionary history of a given gene family is a fundamental problem in comparative and evolutionary genomics with numerous important applications. Solving this problem requires the use of a reconciliation framework, where the input consists of a gene family phylogeny and the corresponding species phylogeny, and the goal is to reconcile the two by postulating speciation, gene duplication, horizontal gene transfer and gene loss events. This reconciliation problem is referred to as duplication-transfer-loss (DTL) reconciliation and has been extensively studied in the literature. Yet, even the fastest existing algorithms for DTL reconciliation are too slow for reconciling large gene families and for use in more sophisticated applications such as gene tree or species tree reconstruction

Efficient inference of bacterial strain trees from genome-scale multilocus data

Motivation: In bacterial evolution, inferring a strain tree, which is the evolutionary history of different strains of the same bacterium, plays a major role in analyzing and understanding the evolution of strongly isolated populations, population divergence and various evolutionary events, such as horizontal gene transfer and homologous recombination. Inferring a strain tree from multilocus data of these strains is exceptionally hard since, at this scale of evolution, processes such as homologous recombination result in a very high degree of gene tree incongruence

New methods ring changes for the tree of life

Relationships among prokaryotes and the origin of eukaryotes have both proven controversial, with results depending upon the gene sequences and methods used. Extensive horizontal gene transfer is one possible reason why inferring such deep phylogenetic relationships is difficult. In two recent papers, Lake and Rivera introduce new methods that can be used to reconstruct the genomic tree in the presence of horizontal gene transfers, but which suggest that a ring rather than a tree is a better representation of some parts of the history of life on Earth

New methods ring changes for the tree of life

Relationships among prokaryotes and the origin of eukaryotes have both proven controversial, with results depending upon the gene sequences and methods used. Extensive horizontal gene transfer is one possible reason why inferring such deep phylogenetic relationships is difficult. In two recent papers, Lake and Rivera introduce new methods that can be used to reconstruct the genomic tree in the presence of horizontal gene transfers, but which suggest that a ring rather than a tree is a better representation of some parts of the history of life on Earth

Inferring explicit weighted consensus networks to represent alternative evolutionary histories

Background: The advent of molecular biology techniques and constant increase in availability of genetic material have triggered the development of many phylogenetic tree inference methods. However, several reticulate evolution processes, such as horizontal gene transfer and hybridization, have been shown to blur the species\ud evolutionary history by causing discordance among phylogenies inferred from different genes.\ud Methods: To tackle this problem, we hereby describe a new method for inferring and representing alternative(reticulate) evolutionary histories of species as an explicit weighted consensus network which can be constructed from a collection of gene trees with or without prior knowledge of the species phylogeny.\ud Results: We provide a way of building a weighted phylogenetic network for each of the following reticulation\ud mechanisms: diploid hybridization, intragenic recombination and complete or partial horizontal gene transfer. We successfully tested our method on some synthetic and real datasets to infer the above-mentioned evolutionary events which may have influenced the evolution of many species.\ud Conclusions: Our weighted consensus network inference method allows one to infer, visualize and validate statistically major conflicting signals induced by the mechanisms of reticulate evolution. The results provided by the new method can be used to represent the inferred conflicting signals by means of explicit and easy-to-interpret phylogenetic networks

Relative time constraints improve molecular dating

Dating the tree of life is central to understanding the evolution of life on Earth. Molecular clocks calibrated with fossils represent the state of the art for inferring the ages of major groups. Yet, other information on the timing of species diversification can be used to date the tree of life. This is the case for instance for horizontal gene transfer events and ancient coevolutionary relationships such as (endo)symbioses, which can imply temporal relationships between two nodes in a phylogeny (Davín et al. 2018). This can be particularly helpful when the geological record is sparse, e.g. for microorganisms, which represent the vast majority of extant and extinct biodiversity