Salamanders represent the most endangered Order of amphibians worldwide, underscoring the critical importance of understanding their behaviour and ecological significance for effective conservation efforts. This thesis is dedicated to investigating the dietary habits of the golden Alpine salamander, a small urodele subspecies endemic to a limited geographical area bordering the Province of Trento and Veneto, classified as Endangered (EN) by the Italian IUCN Red List Committee due to its restricted range and degradation of its habitat. This study uses COI metabarcoding to analyse stomach contents providing the first insight into the diet of this species with three primary objectives: firstly, to develop a protocol that ensures DNA preservation and prevents contamination throughout the sampling and analysis process; secondly, to characterise the feeding habits of this urodele and its role in the trophic chain; and finally, to compare the results of the traditional morphological analysis with the COI metabarcoding approach. The study was conducted for the S. a. aurorae population located in the municipality of Levico Terme, Trentino-Alto Adige/Südtirol, Italy. Individual animals were collected during a survey of 31 plots (20 m x 20 m) over a three-day period in late July 2022. In total, 53 salamanders were captured, stomach contents were collected using flushing (a non-lethal method), and subsequently released where captured. Stomach contents were analysed in the Platform for Animal, Environmental and Antique DNA at the Fondazione E. Mach. The results obtained validate the efficacy of the developed protocol and underscore the pivotal role of high-throughput sequencing techniques like COI metabarcoding in environmental sample analysis. COI metabarcoding revealed the importance of dipterans, myriapods, and spiders as primary trophic sources in the diet of the Golden Alpine salamander, offering detailed insights into the genera, families, and orders comprising its dietary preferences. Interestingly, no discernible food preferences were observed between sexes or between pregnant and non-pregnant females. The thesis highlights the Golden Alpine salamander's role as a key predator in maintaining the equilibrium of soil mesofauna communities within its habitat, emphasizing the species' importance in local ecosystems. Finally, the molecular method demonstrates a significantly higher taxonomic resolution then morphological analysis, identifying 129 prey taxa, including the remarkable number of 97 Genera.
Gli urodeli rappresentano l'ordine di anfibi più minacciato a livello globale, evidenziando l'urgente necessità di intraprendere efficaci azioni di conservazione. Questa tesi si è concentrata sull'indagine delle abitudini alimentari della salamandra di Aurora, una sottospecie endemica italiana, il cui areale è limitato a circa 26 chilometri quadrati situati al confine tra le province di Trento e Vicenza. A causa del progressivo degrado dell'habitat e della limitata estensione territoriale, il Comitato Italiano delle Liste Rosse IUCN ha classificato la salamandra di Aurora come specie in pericolo (EN). Questo studio presenta la prima analisi dei campioni stomacali della salamandra di Aurora, con tre obiettivi principali: sviluppare un nuovo protocollo per garantire la preservazione del DNA ed evitare la contaminazione durante il campionamento e le fasi di analisi; caratterizzare la dieta e comprendere il suo ruolo all'interno della rete trofica; confrontare il metodo morfologico con quello del COI metabarcoding. Alla fine di luglio 2022, sono stati condotti tre surveys nel sito di presenza della salamandra, situato nel comune di Levito Terme, Trentino-Alto Adige/Südtirol, comprendendo un'area di circa 12 chilometri quadrati divisa in 31 plot (20 m x 20 m). In totale sono state catturate 53 salamandre adulte, campionate attraverso lo stomach flushing (una tecnica non letale) e poi rilasciate. Il contenuto stomacale è stato analizzato prima con il metodo morfologico presso il MUSE e poi con il metodo di COI metabarcoding presso la Piattaforma per il DNA animale, ambientale e antico della Fondazione E. Mach. I risultati ottenuti hanno confermato l'efficacia del protocollo e sottolineato il ruolo centrale delle tecnologie di sequenziamento ad alto rendimento (HTS) nell'analisi dei campioni ambientali. Grazie al COI metabarcoding, è stato possibile scoprire che i ditteri, i miriapodi e i ragni costituiscono la principale fonte trofica della salamandra di Aurora. In totale sono stati identificati 129 taxa a livello tassonomico di Ordine, Genere e Famiglia. Non sono emerse evidenti differenze di preferenza alimentare né tra i sessi né tra le femmine gravide e non gravide. I risultati indicano che la salamandra di Aurora è un predatore generalista e potrebbe svolgere un ruolo di primaria importanza nel mantenere l'equilibrio della comunità di invertebrati del suolo. Infine, il metodo molecolare ha dimostrato una risoluzione tassonomica significativamente più elevata rispetto all'analisi morfologica, identificando 129 prede, tra cui un interessante numero di 97 Generi.
Diet characterisation of the endemic Golden Alpine salamander Salamandra atra aurorae (Caudata: Salamandridae) using DNA metabarcoding of stomach contents
POLLI, FEDERICO
2023/2024
Abstract
Salamanders represent the most endangered Order of amphibians worldwide, underscoring the critical importance of understanding their behaviour and ecological significance for effective conservation efforts. This thesis is dedicated to investigating the dietary habits of the golden Alpine salamander, a small urodele subspecies endemic to a limited geographical area bordering the Province of Trento and Veneto, classified as Endangered (EN) by the Italian IUCN Red List Committee due to its restricted range and degradation of its habitat. This study uses COI metabarcoding to analyse stomach contents providing the first insight into the diet of this species with three primary objectives: firstly, to develop a protocol that ensures DNA preservation and prevents contamination throughout the sampling and analysis process; secondly, to characterise the feeding habits of this urodele and its role in the trophic chain; and finally, to compare the results of the traditional morphological analysis with the COI metabarcoding approach. The study was conducted for the S. a. aurorae population located in the municipality of Levico Terme, Trentino-Alto Adige/Südtirol, Italy. Individual animals were collected during a survey of 31 plots (20 m x 20 m) over a three-day period in late July 2022. In total, 53 salamanders were captured, stomach contents were collected using flushing (a non-lethal method), and subsequently released where captured. Stomach contents were analysed in the Platform for Animal, Environmental and Antique DNA at the Fondazione E. Mach. The results obtained validate the efficacy of the developed protocol and underscore the pivotal role of high-throughput sequencing techniques like COI metabarcoding in environmental sample analysis. COI metabarcoding revealed the importance of dipterans, myriapods, and spiders as primary trophic sources in the diet of the Golden Alpine salamander, offering detailed insights into the genera, families, and orders comprising its dietary preferences. Interestingly, no discernible food preferences were observed between sexes or between pregnant and non-pregnant females. The thesis highlights the Golden Alpine salamander's role as a key predator in maintaining the equilibrium of soil mesofauna communities within its habitat, emphasizing the species' importance in local ecosystems. Finally, the molecular method demonstrates a significantly higher taxonomic resolution then morphological analysis, identifying 129 prey taxa, including the remarkable number of 97 Genera.The text of this website © Università degli studi di Padova. Full Text are published under a non-exclusive license. Metadata are under a CC0 License
https://hdl.handle.net/20.500.12608/62208