Ascidian Identification, Phylogeny and Systematics

Ascidians (Phylum: Chordata, Class: Ascidiacea), or sea squirts, are the largest and most diverse class of the sub-phylum Tunicata (also known as Urochordata). Recent phylogenomic studies place the tunicates as the sister group to the vertebrates suggesting they are our closest relatives among the invertebrates and providing a fertile ground for evolutionary and developmental studies. During the past two decades enormous progress has been achieved in the fields of development, evolution, immunology, natural products and ecology of ascidians.

Despite the enormous progress that has been achieved in the field of ascidian research worldwide, only a few studies have focused on the ascidians of the Red Sea and the Eastern Mediterranean. ­­­­During my graduate work with Professor Yossi Loya, Tel-Aviv University, I studied ecological aspects of the ascidian fauna along the coasts of Israel. I began training as an ascidian taxonomist and established a museum collection of this group at the National Collections of Natural History at Tel Aviv University. This collection is unique because it enables future molecular studies on material preserved in Ethanol together with classic taxonomic studies on the matching species. My collaboration with the Smithsonian Barcoding of Life project resulted in the sequencing of the cytochrome c oxidase subunit I from all specimens in my collection.

I continue to apply and enhance my approach of combining molecular tools with classic morphological observations through my post-doc research at the Biology Department, University of Washington. This perspective assisted in resolving a long term debate regarding cases of synonymy in Molgulid ascidian, and in revealing a possible novel vector for transport of marine species through the Northwest Passage. In addition I published a description of a new species from the coral reefs of Eilat, Israel. As a co-editor of the Ascidiacea and Hemichordata taxa in the World Register of Marine Species database, I have initiated a taxonomic database for each group, combining accurate systematic classification with molecular data , In that capacity we (a group of editors) are compiling a large scale review of global marine biodiversity. I recently submitted a review article on the global distribution of the class Ascidiacea to a special collection of the magazine PLoS One. This review is the first to provide a global perspective of the current systematic and geographic knowledge of this class. A large component of my post-doc work involved molecular research in which I used nuclear genes exhibiting a molecular-clock like behavior to settle unresolved questions in deutrostome evolution, and ascidian development in particular. This data is currently in the stage of final analysis.