Despite the functional and phyletic ubiquity of highly polymorphic genetic recognition systems, the evolution and maintenance of these remarkable loci remain an empirical and theoretical puzzle. Many clonal invertebrates use polymorphic genetic recognition systems to discriminate kin from unrelated individuals during behavioral interactions that mediate competition for space. Space competition ...

Numerous colonies of the invasive colonial ascidian Didemnum vexillum Kott, 2002 have been found in the Lagoon of Venice (Italy) in 2012, overgrowing fouling organisms on maritime structures such as docks, pilings, and pontoons. This is the first record for the Mediterranean Sea. A survey conducted in July 2012 revealed that D. vexillum is present in the euhaline and tidally well flushed zones ...

We explored the usefulness of mtDNA data in assessing phylogenetic relationships within the Ascidiacea. Although ascidians are a crucial group in studies of deuterostome evolution and the origin of chordates, little molecular work has been done to ascertain the evolutionary relationships within the class, and in the studies performed to date the key group Aplousobranchiata has not been adequate...

During the implementation of a large project aimed to investigate the benthic community structures of the Sea of Marmara, specimens of the invasive ascidian species Styela clava were collected on natural substrata (rocks) at 10 m depth at one locality (Karamürsel) in İzmit Bay. The specimens were mature, containing gametes, indicating that the species had become established in the area. The Sea...

In many bilaterian embryos, nuclear β-catenin (nβ-catenin) promotes mesendoderm over ectoderm lineages. Although this is likely to represent an evolutionary ancient developmental process, the regulatory architecture of nβ-catenin-induced mesendoderm remains elusive in the majority of animals. Here, we show that, in ascidian embryos, three nβ-catenin transcriptional targets, Foxa.a, Foxd and Fgf...

BACKGROUND Ascidians play a key role in the ecology and biodiversity of marine ecosystem. Ascidians can be transported in ship ballast water and while attached to ship and boat hulls. Heavy traffic by domestic and international ships as well as cargo vessels between the major and minor ports warrants continuous monitoring for new introductions of ascidians. The Mandapam coast is situated in the...

Ascidian species (Tunicata: Ascidiacea) usually have tailed, hatching tadpole larvae. In several lineages, species have evolved larvae that completely lack any tail tissues and are unable to disperse actively. Some tailless species hatch, but some do not hatch before going through metamorphosis. We show here that ascidian species with the highest speciation rates are those with the largest rang...