MOLECULAR EVIDENCE OF EARLY ANIMAL EVOLUTION: ARE WE MAKING ANY PROGRESS?

Genomic data are now available for a large number of taxa including a moltitude of non bilaterian metazoan, and a diversity of studies have been published in the last few years addressing early animal evolution, their implications for our understanding of Ediacaran and Canbrian paleoecology, and the origin of complex morphological traits. Similarly, the importance of molecular data to date the root of the animal tree has increased. While a general pattern seemed to have emerged where the sponges were seen as the sister group to all the other animals (Philippe et al. 2009; Sperling et al. 2009) and the gap between the molecular and the fossil records was descreasing (Erwin et al. 2011), recent studies challanged these views, suggesting instead that the animals had deep Mesoproterozoic origins (Battistuzzi et al. 2015) and and that the ctenophores, not the sponges, should be considered the sister group of all the other animals (Ryan et al. 2013; Moroz et al. 2014; Whelan et al. 2015). Here I will present new phylogenetic and molecular clock results illustrating how both views are unsupported and results from the application of poorly performing molecular clock and phylogenetic methods. Sponges are still the most likely sister group of the other animals, while a Mesoproterozoic origin of the animals is to be considered rejected in full.