Meeting Abstract
Ecdysozoa represent one of the three main lineages of bilaterally symmetrical animals. The oldest, confirmed, fossil evidence of bilateral animal activity is represented by the ~541 million of years old feeding traces of an ecdysozoan (the priapulid worm like animal – Treptichnus pedum), and since then ecdysozoans have consistently dominated the phanerozoic ecosystems. To date, ecdysozoans constitute the largest majority of animal biodiversity (with the phylum Arthropoda), and animal body mass (with the phylum Nematoda). Ecdysozoans are of fundamental scientific importance as this lineage include the genetic and development model systems (the fly D. Melanogaster and the worm C. elegans), from which most of our knowledge of phenotype-genotype mapping stems. Understanding ecdysozoan evolution is fundamental to clarify the origin and evolution of extant animal biodiversity. However, to be able to correctly answers fundamental questions in ecdysozoan evolution, e.g. was the last common ecdysozoan ancestor segmented? We first need to clarify ecdysozoan relationships. Here, I shall summarise currently knowledge in ecdysozoan phylogenetics and present new results bearing on our understanding of the relationships and divergence times among the ecdysozoan phyla. I shall contend that while in most cases there is agreement between scholars, the relationships of some fundamental ecdysozoan phyla (like the Tardigrada – water bears) are still unclear, and will need further investigations.
