Biogeography and connectivity of black and gold corals along the Mediterranean and North East Atlantic twilight zone

Internship position (12 ECTS)
The highly variable Pleistocene climatic variations, during which glacial/interglacial periods caused multiple range shifts have shaped the genetic structure and diversity of European biodiversity. Fingerprints have been left by these events on the current genetic diversity of species and the past influence can help to predict future consequences of further changes in climatic variables. The twilight or mesophotic zone (30-150 m depth) is amongst the least explored marine areas, particularly in temperate regions. Along the Mediterranean and North East Atlantic, two of the least studied habitat-forming species are the black (Anthiphatella subpinnata) and gold (Savalia savaglia) corals. They are a common component of the lower fringe of the circalittoral twilight environment, given availability of hard substrate. Their colonies create elevated and complex tertiary structures that represent important three-dimensional habitats. They host a rich associated fauna and attract numerous species of commercial interest. However, these corals are particularly vulnerable to direct damages (e.g., commercial fishing activities) because of their arborescent morphology and generally low growth rate. S. savaglia is a rare zoanthid inhabiting the Mediterranean and North Eastern Atlantic Ocean. Owing to its rarity, the species is included in the Annex II ASPIM (Barcelona Convention) and in the Annex II of the Berna Convention on the conservation of European wildlife and natural habitats. It is the unique zoanthids able to produce a rigid and thick skeleton. A. subpinnata is a large, branched, antipatharian with an Atlanto-Mediterranean distribution. It is unknown whether the species retain differentiated populations and hotspots of unique genetic diversity along their range, presumed to occur along long-term persistence zones. Objectives: The proposed project will cover three objectives: 1) To estimate the genetic diversity and differentiation within and between populations of Antipathella subpinnata and Savalia savaglia along their distributional range; 2) To identify barriers to gene flow and infer the likely past demographic causes of present genetic patterns; and 3) To identify conservation units in both species. Samples have been collected across most of the distributional ranges of both species to cover the Mediterranean and neighboring Atlantic zones. These will be genotyped and/or sequenced for multiple loci using high resolution nuclear and mitochondrial markers already available, to recover the ancient biogeographic/demographic history of the species. The tools involved will be focused on the use of molecular genetic techniques, microsatellites and mitochondrial DNA sequences and/or SNP markers obtained using NGS approaches for the study of the genetic structure and impact of changes in connectivity.
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Federica Costantini
Reference Number: RP-49051