Multigene Family Evolution: Patterns and processes of gene gain and loss. Dr. Julio Rozas Universitat de Barcelona.

Título: Multigene Family Evolution: Patterns and processes of gene gain and loss

Ponente: Julio Rozas. Catedrático de Genética. Universitat de Barcelona

Presentado por: Rafael Zardoya, Dpto. Biodiversidad y Biología Evolutiva, MNCN-CSIC

Resumen:

The chemosensory system is essential for the survival and reproduction of organisms. In insects, it allows the detection of food and predators, as well as the discrimination of soluble stimulants that elicit feeding behaviours and initiate innate sexual and reproductive responses. The first steps of the chemosensory process are mediated by extracellular ligand-binding (OBP and CSP) and membrane receptor (OR, GR and IR) proteins, which are encoded in moderately-sized multigene families. Here, I examine the mechanisms determining the origin, maintenance and evolutionary fate of the chemosensory gene families at different levels.

We inferred that the chemosensory families, as most gene families, are highly dynamic with high turnover rates and evolve under the birth-and-death process. Currently, several stochastic birth-and-death models and programs have been developed to analyze gene family dynamics. Nevertheless, these programs have some drawbacks, including unrealistic assumptions about gene family evolution, or the inability to specify branch models. We have developed BadiRate, a likelihood-based method that implements five different stochastic population models to estimate family turnover rates (birth, gain, death, innovation), as well as the most likely ancestral gene family size. Moreover, the method allows detecting expanding/contracting gene families and phylogenetic lineages with extreme turnover rates. These families and lineages are good candidates to further analyse the evolutionary processes shaping gene copy number variation.

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