AnnEvol - Evolution and phylogeny of Annelida based on phylogenomic data (i.e. EST libraries)

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Annelida is an ancient and very diverse animal taxon inhabiting diverse habitats from the deep sea to terrestrial soils. Being one of the three animal groups with segmentation, deciphering the evolution of Annelida is crucial to our understanding of the evolution of segmentation. Traditionally, Annelida comprised polychaetes (e.g., lugworms) and clitellates (e.g., earthworms and leeches). While the placement of Clitellata within polychaetes is well supported, their polychaete sistergroup is uncertain. It has been shown that the unsegmented animal “phyla” Sipuncula and Echiura as well as Myzostomida are part of the annelid radiation, but except for Echiura their annelid sistertaxa remain undetermined. Although more inclusive taxonomic units (Scolecida, Palpata, Canalipalpata, and Aciculata) have been put forward, resolving annelid relationships has been difficult using either morphological or molecular single or multiple gene data. Thus, the phylogeny of Annelida is still unresolved and any conclusions about the evolution of Annelida, like the form of the ancestral annelid either as burrowing or as crawling are contentious. This is calling into question the use of exemplar species as representatives of the ancestral annelid condition (e.g., Platynereis). On the other hand, preliminary data gathered by the two applicants show that substantially increasing the amount of molecular data per taxon using expressed sequence taqs (= EST) libraries results in an increase in both nodal support and congruence between analyses. Therefore, in this proposed project we want to resolve the phylogeny of Annelida using a phylogenomic approach based on EST libraries. EST libraries of several annelids shall be generated using 454 sequencing. This increases the amount of sequence information per taxon by three to four orders of a magnitude in comparison to the amplification of specific genes. We expect to robustly resolve the backbone of the annelid tree of life given our taxon sampling and thus to contribute to conclusions regarding the evolution of Annelida.