Evolution and Phylogeny of Annelida

Project Title: Phylogeny of Annelida, phylogenetic position of interstitial polychaeta taxa of supposedly paedomorphic origin

Funding Source: University, DFG, USA NSF

Principle Investigator: Günter Purschke. This is a collaboration with Torsten H. Struck (Oslo), Cristoph Bleidorn (Göttingen) and Kenneth M. Halanych (Auburn)

Investigations on evolution, systematics, phylogeny and functional morphology are in the focus of interest. Currently these investigations are carried out on annelids, the segmented worms, and those taxa which are presumed to be closely related to them. Special emphasis is laid to the phylogenetic relationships within and validity of Lophotrochozoa.

During the past years great progress has been made unraveling the evolution and phylogenetic relationships within Annelida. However, many questions are still either being unresolved or controversially discussed. Clarifying the evolutionary history of this diverse and biologically important taxon will elucidate our understanding how their bauplan (segmentation) was capable for successful adaptation to various environmental conditions, and thus resulting in an extraordinary high diversity. For example, a variety of species inhabits the interstitial realm, the space between the sand grains, and it could be shown that those groups formerly regarded as archiannelids, and comparatively close to the annelid stem species, are nothing else but highly specialized and derived, secondarily simplified and belong to two different convergent lineages characterized by two different evolutionary pathways: Progenesis and Miniaturization.

Trilobodrilus axi and Saccocirruspapillocercus.