Unlocking the evolutionary history of the mighty Bluefin Tuna using novel paleogenetic techniques and ancient tuna remains

Mediterranean civilizations and the Atlantic bluefin tuna (Thunnus thynnus) have shared a dramatic history spanning millennia. Today, traditional fishing techniques are fading into the past and industrial fisheries command the seas. Analyzing tuna bones recovered from archeological excavations throughout Europe, we aim to reconstruct the species’ adaptive responses to fisheries pressure and climate change. Using novel molecular techniques, DNA has been extracted from bluefin tuna vertebrae excavated from late iron age and ancient roman settlements in coastal Iberia (4th-­-2nd century BC) and Byzantine-­-era Constantinople (4th-­-15th century AD), as well as vertebrae from the Massimo Sella archive located at the University of Bologna (Ionian, Tyrrhenian and Adriatic Seas, early 20th century). The species identity of all samples has been verified using newly developed mini-­- barcodes targeting mitochondrial and nuclear markers. Samples have been quantified and analyzed using multiple technique (qPCR, Agilent BioAnalyzer), in order to correlate Atlantic bluefin tuna DNA content with samples’ age and diagenetic processes. Suitable samples were selected for subsequent high-­- throughput sequencing on Ion Torrent platform to assess temporal genomic changes induced by environmental and natural history drivers. All historical samples, along with modern ones collected from the same geographic areas, have been genotyped with a dedicated SNP panel, which is composed of 76 SNPs with high similarity to a wide variety of annotated genes and additional 20 SNPs that provide significant discrimination between modern populations. These efforts will provide new insights into the spatial dynamics, population structure and genetic evolution of the species over the past 2000 years