MONOPHYLY AND PHYLOGENETIC PLACEMENT OF OSTRACODA BASED ON NEXT-GENERATION SEQUENCING DATA (Invited Presentation)

An ambitious, yet fundamental goal for comparative biology is to understand the evolutionary relationships for all of life. Yet many important taxonomic groups have remained recalcitrant to inclusion into broader scale studies. Here, we focus on collection of 9 new 454 transcriptome data sets from Ostracoda, a group that is often under-sampled in broader studies. We combine the new transcriptomes with a new morphological matrix (including fossils) and existing Expressed Sequence Tag (EST), mitochondrial genome, nuclear genome and rDNA data, which leads to new insights into ostracod and pancrustacean phylogeny. We obtained support for three epic pancrustacean clades that likely originated in the Cambrian: Oligostraca (Ostracoda, Mystacocarida, Branchiura, Pentastomida); Multicrustacea (Copepoda, Malacostraca, Thecostraca); and a clade we refer to as Allotriocarida (Hexapoda, Remipedia, Cephalocarida, Branchiopoda). Our support of Allotriocarida is counter to the Vericrustacea hypothesis that puts Branchiopoda with Multicrustacea. Looking within the Oligostraca clade, our results support the unresolved question of ostracod monophyly. Within Multicrustacea, we find support for Thecostraca plus Copepoda, for which we suggest the name Hexanauplia. Within Allotriocarida, some analyses support the hypothesis that Remipedia is the sister taxon to Hexapoda, but others support Brachiopoda+Cephalocarida as the sister group of hexapods. Across hypotheses, we sometimes see better support for equivocal nodes using slow-evolving genes or when excluding distant outgroups, highlighting the increased importance of conditional data combination in this age of abundant, often anonymous data. By concatenating molecular and morphological data, we place pancrustacean fossils in the phylogeny, which can be used for studies of divergence times in Pancrustacea, Arthropoda, or Metazoa. Our results and new data will allow for attributes of Ostracoda, such as its amazing fossil record and diverse biology, to be leveraged in broader scale comparative studies. Further, we illustrate how adding extensive next-generation sequence data from understudied groups can yield important new phylogenetic insights into long-standing questions, especially when carefully analyzed in combination with other data.