Probabilistic gene-species tree reconciliation with lateral transfers

by Joel Sjöstrand (KTH)

Wednesday 27 May 2009, 16:00 → 17:00 Europe/Stockholm

RB35 (RB35)

While gene duplication and loss are generally acknowledged as major evolutionary forces, there is a growing awareness of the importance of lateral (horizontal) gene transfers, LGTs, for gene family evolution in particularly single-celled species. However, phylogenetic characterization of families where LGT events are prevalent is notoriously cumbersome due to the inherent incongruence between a family and its species tree.

We present ongoing work on DTLRS, a novel generative model where a gene family evolves embedded in a species tree by means of duplications, losses, and more interestingly, LGTs, in a birth-death process-like manner. The model has been applied in a Bayesian MCMC framework, enabling us to perform probabilistic orthology analysis, taking the species tree into account alongside sequence evolution with a relaxed molecular clock.

This opens up the possibility of gene tree inference even in LGT-prone cases, and may provide estimates on LGT rates and counts as opposed to duplications. Some initial results on synthetically generated data, verifying the soundness of our implementation, is presented, together with a discussion of what lies ahead.