My current focus is on sourcing samples, both Barracuda (BRC) and Bottlenose Dolphin (BND). My hunt for BND samples is going smoother, but only slightly. Fortunately, two ex-PhD students of my supervisor, Dr Ada Natoli & Dr Stefania Gaspari, have been very kind in allowing me to take sub-samples from their own personal archive of BND samples. Dr Ada Natoli has a substantial collection of BND samples stored here at Durham within the School of Biological & Biomedical Sciences. This archive covers samples from across Europe and contains 20 from the Italian region.
By Italian region I am referring to any samples coming from the Adriatic, Ligurian, Tyrrhenian and Ionian seas. Most of these 20 samples are from Northern Italy and not the area around Sicily that is of most interest to my project. This is not to say that Northern Italy samples are without value, far from it as I require samples that area to allow me to determine the steepness and exact position of the genetic transition between populations. The Adriatic is also of interest owing to its strong environmental North-South gradients in variables such as salinity and depth. This is important as it will allow us to ask just how concise a habitat change needs to be in order to influence population structure.
Dr Stefania Gaspari’s archive of BND samples is housed at the University of Lincoln under the care of Dr André Moura. I spent time last week at the Joseph Banks Laboratories, University of Lincoln, measuring DNA concentration of samples within the archive. This then allowed me to compile a list of useable samples from the Italian region based on the requirements that taking the 250ng of DNA needed for RADseq library preparation would not compromise the archive coverage. After identifying 58 suitable samples Dr Gaspari kindly allowed me to take my required volume of sample. Much like Dr Natoli’s archive the geographic distribution of samples acquired from Lincoln showed considerable sparsity around Southern Italy and Sicily. This is something that we may have to address in time.
The collection of BRC samples has brought with it plenty of different obstacles. Selecting Yellowmouth Barracuda as our comparative fish species has been the first challenge. The requirements for this position stipulated that the fish be a large, high trophic level species that shows regional residency and some evidence of population differentiation across the Siculo-Tunisian Front (STF). Tuna species show evidence of genetic differentiation across the STF (Carlsson et al 2004) but often travel long distances within the Mediterranean and beyond ( Davies et al 2011; De Metrio et al 2002) and so do not meet the regional residency requirement. Many other fish such as the Tortonese’s Goby, Chub Mackerel and Mackerel and others all exhibit genetic differentiation across the STF (Mejri et al 2009; Zardoya et al 2004) but are not high trophic level predators. Quickly the Yellowmouth Barracuda became a firm focus. It feeds at a high trophic level (Barreiros et al 2002), has shown hints of genetic differentiation across the STF (Milana et al 2014) and some evidence of being regionally resident (Barreiros et al 2002).
I then began to start investigating how I could acquire BRC samples and through communication with native Italian researchers and very helpful fishing enthusiasts on the online fishing forum Mercatino Della Pesce it has become apparent that I cannot simply collect samples from Italian fish markets as they are seen there infrequently. So far I have one sample of BRC, kindly donated to me by Salvatore Papasergi from Palermo, Sicily. Where the rest of my samples will come from remains to be seen…
Barreiros, J. P., Santos, R. S., & Borba, A. E. S. D. (2002). Food habits, schooling and predatory behaviour of the Yellowmouth Barracuda, Sphyraena viridensis Cuvier, 1829 (Perciformes: Sphyraenidae) in the Azores.
Carlsson, J., McDowell, J. A.N., Díaz‐Jaimes, Píndar. O., Carlsson, J. E., Boles, S. B., Gold, J. R., & Graves, J. E. (2004). Microsatellite and mitochondrial DNA analyses of Atlantic bluefin tuna (Thunnus thynnus thynnus) population structure in the Mediterranean Sea. Molecular Ecology, 13(11), 3345-3356.
Davies, C. A., Gosling, E. M., Was, A., Brophy, D., & Tysklind, N. (2011). Microsatellite analysis of albacore tuna (Thunnus alalunga): population genetic structure in the North-East Atlantic Ocean and Mediterranean Sea. Marine biology, 158(12), 2727-2740.
De Metrio, G., Arnold, G. P., Block, B. A., De la Serna, J. M., Deflorio, M., Cataldo, M., … & Seitz, A. (2002). Behaviour of post-spawning Atlantic bluefin tuna tagged with pop-up satellite tags in the Mediterranean and eastern Atlantic. ICCAT Col. Vol. Sci. Pap, 54(2), 415-424.
Mejri, R., Lo Brutto, S., Hassine, O. K. B., & Arculeo, M. (2009). A study on Pomatoschistus tortonesei Miller 1968 (Perciformes, Gobiidae) reveals the Siculo-Tunisian Strait (STS) as a breakpoint to gene flow in the Mediterranean basin. Molecular Phylogenetics and Evolution, 53(2), 596-601.
Milana, V., Ciampoli, M., & Sola, L. (2014). mtDNA sequences of Sphyraena viridensis (Perciformes: Sphyraenidae) from Italy: insights into historical events and the phylogeny of the genus. Biological Journal of the Linnean Society, 113(2), 635-641.
Zardoya, R., Castilho, R., Grande, C., Favre‐Krey, L., Caetano, S., Marcato, S., … & Patarnello, T. (2004). Differential population structuring of two closely related fish species, the mackerel (Scomber scombrus) and the chub mackerel (Scomber japonicus), in the Mediterranean Sea. Molecular Ecology, 13(7), 1785-1798.