Dr. Davide Pisani from the University of Bristol spoke today about his work using molecular phylogenetics in order to resolve the earliest branches on the Animal tree of life.
His talk was based on a recent paper in PNAS from his research group in Bristol and collaborators.
The main thrust of this argument is that a traditional placement of sponges (Porifera) as the earliest division of the animals is supported by molecular data and good phylogenetic methods, while an alternative placement of Ctenophores as the sister-group of the rest of the animals is not well-supported. Additionally, the placement of the Ctenophores as the sister-group requires two additional ad hoc hypotheses - that Ctenophores independently evolved a nervous system and that Sponges became secondarily simplified.
The talk was, as usual, very animated and presented with gusto, was well-received by the audience and provided us with lots of stimulating conversations afterwards.