## Hybridisation between species
+_C. intestinalis_ and _C. savignyi_ can cross-fertilise after removal of the
+vitelline enveloppe ([[Byrd and Lambert, 2000|biblio/10602281]]).
+
_Ciona robusta_'s sperm can efficiently fertilise _C. intestinalis_ eggs, but
the fertilisation rates are much lower in the reciprocal crosses ([[Suzuki,
Nishikawa and Bird, 2005|biblio/16205978]], [[Caputi and coll.,
analysis of wild animals of ([[Bouchemousse and coll., 2016|biblio/27662427]])
were F1 and of _C. int_ maternal origin.
-_C. intestinalis_ and _C. savignyi_ can cross-fertilise after removal of the
-vitelline enveloppe ([[Byrd and Lambert, 2000|biblio/10602281]]).
+_C. roulei_ can cross-hybridise easily with _C. intestinalis_, suggesting
+that they are the same species ([[Malfant, Darras and Viart, 2018|biblio/29367599]]).
## Detailed evidence for speciation