Molecular systematics of the Southwestern Atlantic Octocorallia (Cnidaria: Anthozoa), with emphasis on deep-sea species

Abstract

The Southwestern Atlantic (SWA) hosts one of the most poorly known octocoral faunas (Cnidaria: Anthozoa: Octocorallia) in the world. In deep sea (>50 m), where more than 75% of those species occur, that group is the main builder of coral gardens. These habitats host the highest diversities of metazoans in continental shelves and slopes. However, due to the paucity of studies, most part of the systematics of the group is based on groupings considered as unnatural. Several of the phylogenetically inconsistent groups are well represented of Brazil, Uruguay and Argentina. That makes the SWA fauna particularly important to solve problems in the systematics of the suborder. Besides that, lack of knowledge on population connectivity and reproductive strategies compromise management and conservation plans for deep-sea coral ecosystems in that region, which have been exposed to several anthropogenic impacts. In this context, information at ecological and molecular levels is fundamental in order to understand: i) species complexes; ii) phylogenetically artificial groups; iii) reproductive strategies; iv) and biogeographic relationships within that fauna. Aiming to clarify these questions, the present proposal will: a) perform a biodiversity assessment of the octocoral fauna in the SWA, based on both morphological and molecular evidence (barcoding); b) to assess connectivity between SWA populations, using molecular markers; c) to assess gametogenesis in some key-species; d) to propose rearrangements in the systematics of the group, based on molecular phylogenetic reconstructions; and e) to propose identification keys for species occurring in the study area.