Mol Phylogenet Evol. 2010 Aug;56(2):718-26. doi:10.1016/j.ympev.2010.03.042

Nydam ML and Harrison RG

Polymorphism and divergence within the ascidian genus Ciona.

Sequencing of nuclear genes show intragenic recombination in C. robusta and C. intestinalis, buy supports monophyly of these two species. The data also supports paraphyly of C. intestinalis with respcet to Ciona roulei.