3 resultados para Molecular Marker

em AMS Tesi di Laurea - Alm@DL - Università di Bologna


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A total of 352 specimens were analyzed to achieve the different aims of this thesis. 255 central-northern Adriatic specimens of S. solea and S. aegyptiaca were molecularly analysed using microsatellite locus Sos(AC)40 and 205 also morphologically due to evaluate the abundance and the distribution of the cryptic species S. aegyptiaca and to confirm morphologic analyses. Morphological and molecular analyses comparated show a correspondence of 96%. A combined morphologic approach could be proposed to apply multiple criteria on the analyzed external morphological keys. The Adriatic Egyptian soles may lives in shallow waters (up 30 m) and in brackish lagoon. 127 samples of Adriatic common sole added to 326 samples of previous studies showed, using mitochondrial marker (CytB), that the Adriatic Sea as contact zone between Tyrrhenian and Aegean Sea, the divergence within the Adriatic Sea is low but significant between central-north and south, with a longitudinal strong gene flow in central-northern side. It’s also showed as in the Adriatic Sea two near-panmictic populations of common sole exist.

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In this study the population structure and connectivity of the Mediterranean and Atlantic Raja clavata (L., 1758) were investigated by analyzing the genetic variation of six population samples (N = 144) at seven nuclear microsatellite loci. The genetic dataset was generated by selecting population samples available in the tissue databases of the GenoDREAM laboratory (University of Bologna) and of the Department of Life Sciences and Environment (University of Cagliari), all collected during past scientific surveys (MEDITS, GRUND) from different geographical locations in the Mediterranean basin and North-east Atlantic sea, as North Sea, Sardinian coasts, Tuscany coasts and Cyprus Island. This thesis deals with to estimate the genetic diversity and differentiation among 6 geographical samples, in particular, to assess the presence of any barrier (geographic, hydrogeological or biological) to gene flow evaluating both the genetic diversity (nucleotide diversity, observed and expected heterozygosity, Hardy- Weinberg equilibrium analysis) and population differentiation (Fst estimates, population structure analysis). In addition to molecular analysis, quantitative representation and statistical analysis of morphological individuals shape are performed using geometric morphometrics methods and statistical tests. Geometric coordinates call landmarks are fixed in 158 individuals belonging to two population samples of Raja clavata and in population samples of closely related species, Raja straeleni (cryptic sibling) and Raja asterias, to assess significant morphological differences at multiple taxonomic levels. The results obtained from the analysis of the microsatellite dataset suggested a geographic and genetic separation between populations from Central-Western and Eastern Mediterranean basins. Furthermore, the analysis also showed that there was no separation between geographic samples from North Atlantic Ocean and central-Western Mediterranean, grouping them to a panmictic population. The Landmark-based geometric morphometry method results showed significant differences of body shape able to discriminate taxa at tested levels (from species to populations).

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With the discovery that DNA can be successfully recovered from museum collections, a new source of genetic information has been provided to extend our comprehension of the evolutionary history of species. However, historical specimens are often mislabeled or report incorrect information of origin, thus accurate identification of specimens is essential. Due to the highly damaged nature of ancient DNA many pitfalls exist and particular precautions need to be considered in order to perform genetic analysis. In this study we analyze 208 historical remains of pelagic fishes collected in the beginning of the 20th century. Through the adaptation of existing protocols, usually applied to human remains, we manage to successfully retrieve valuable genetic material from almost all of the examined samples using a guanidine and silica column-based approach. The combined use of two mitochondrial markers cytochrome-oxidase-1(mtDNA COI) and Control Region (mtDNA CR), and the nuclear marker first internal transcriber space (ITS1) allowed us to identify the majority of the examined specimens using traditional PCR and Sanger sequencing techniques. The creation of primers capable of amplifying heavily degraded DNA have great potential for future uses, both in ancient and in modern investigation. The methodologies developed in this study can in fact be applied for other ancient fish specimens as well as cooked or canned samples.