Gorgonia mariae and Antillogorgia bipinnata populations inferred from compensatory base change analysis of the internal transcribed spacer 2

- The phylogeny shows two principal clades (Gorgonia and Antillogorgia).
- It is possible to distinguish groups according to population origin.
- Gorgonia clade remains paraphyletic due a specimen from Puerto Rico.
- Compensatory base changes are present between principal clades.
- Hemi-CBCs are present between species and populations.

The systematics within some families of octocorals (Class Anthozoa: Sub-class Octocorallia) remains uncertain in terms of morphological variability and unresolved molecular phylogenies. Elucidating the phylogenetic relationships among octocorals can help for understanding the origin of its huge biodiversity and optimizing conservation plans. The phylogenetic relationships within Gorgoniidae family remain highly polyphyletic. This research explores Gorgonia mariae and Antillogorgia bipinnata populations from several study sites in the Caribbean sea using for the first time the compensatory base changes (CBCs) analysis of the internal transcribed spacer 2 (ITS2) as a molecular tool to elucidate the phylogenetic relationships within the gorgonians. In addition, the mitochondrial gene mtMutS was sequenced in order to complement the nuclear information. This research shows that the presence of CBCs and hemi-CBCs is useful as a complementary tool for providing insights between octocoral species and populations, as well as an approach to figure out the origin of the octocorals biodiversity.

The topology is derived from the sequence-structure synchronous alignment of the ITS2, and the common secondary structures of Gorgonia and Antillogorgia species.189