Tesi di dottorato di ricerca
Migratory behaviour and genetic variation in Western populations of the Stone curlew Burhinus oedicnemus (Charadriiformes, Burhinidae)
Settore scientifico disciplinare
Corso di studi
SCIENZE BIOLOGICHE E MOLECOLARI
tutor Prof. Baldaccini, Natale Emilio
relatore Dott. Giunchi, Dimitri
relatore Dott. Giunchi, Dimitri
- GPS dataloggers
- Mediterranean biodiversity
- population genetic
Data inizio appello
Data di rilascio
The Mediterranean region is considered a hotspot of biodiversity and consequently, a priority area for conservation worldwide in terms of both animal and plant species richness. Due to the uniqueness of habitats and the peculiar features of transitional zone, Mediterranean region's fauna and flora (often endemisms) are highly sensitive to environmental and climate changes.<br>Steppic birds are one of the group mainly suffering from environmental changes and human disturbance. In Europe the mechanization and intensification of agriculture and the change in the land use led to a severe decline of many steppic species. This situation is often worsened by the fact that many steppe bird species have small resident populations isolated in small remnants of suitable habitat, which are often distantly located from each other with limited dispersal opportunities. In order to delineate appropriate conservation plans, understanding of the current population structure of a given species of conservation concern and delineating the exchanges among different populations, as well as their interaction with the habitat, are crucial. In particular for migratory species, the identification of year-round geographical ranges and the quantification of the degree of migratory connectivity are fundamental to exactly define the range where the conservation efforts should be addressed.<br>This PhD project was focused on Stone curlew Burhinus oedicnemus. The Stone curlew is a steppic bird species of conservation concern in Europe whose genetic structure, ecology and spatial behaviour are relatively poorly investigated. The aims of this project were several.<br>Firstly, the level of genetic diversity and rate of exchanges were investigated by means of mitochondrial and nuclear markers among different populations representing the four subspecies inhabiting the western part of the species' distribution range. In particular continental and insular populations were analysed in order to evaluate the genetic structure and the congruence between morphological subspecies and geographic samples. Furthermore, we tested for sex-biased dispersal, comparing patterns of genetic differentiation estimated separately for the sexes by nuclear markers (microsatellites) and comparing the differently inherited markers.<br>Both markers support significant differentiation of the Canary Island populations from those sampled in the Mediterranean basin. Besides, inside Mediterranean basin a relevant level of nuclear genetic diversity was found, with the distinction of several population groups, in particular insular populations, as well as in the Canary Islands. Consequently the four subspecies were confirmed. Microsatellites resulted more efficient than mtDNA markers to detect the differentiation between populations and subspecies, and although sex biased dispersal was not revealed by the specific tests applied to sexed individuals, the different marker performances suggest a probable low dispersal rate, biased in favour of females.<br>Secondly, the wintering areas and migration strategy of a Stone-curlew population breeding in the Taro River Regional Park (Parma, northern Italy) were studied by integrating the information obtained by geolocation and satellite telemetry. Results indicate that tagged Stone-curlews did not leave the Mediterranean basin throughout the year and passed the winter in Sardinia or in Tunisia. Furthermore, GPS loggers resulted useful tools in order to accurately track the birds movements and describe in details the spatial movements of tagged individuals. Although preliminary, the results obtained by the satellite telemetry represent the first evidences of the migration strategy and wintering behaviour of Stone curlew. Both geolocators and GPS loggers results prove the great potential of the use of tracking devices to provide information about migration and non-breeding sites for an elusive species, such as Stone curlew, for which mark-recapture/re-sighting techniques revealed profound limitations.<br>In conclusion, the results presented in this PhD thesis reveal high intraspecific genetic variability in the Western Palaearctic Stone curlews and enlighten a crucial role of islands, both as reservoir of genetic diversity and favourable sites for the species during the whole year. In fact the recorded wintering sites coincided with areas where breeding, possible resident, populations are reported, further emphasising the importance of these areas for the conservation of the Stone curlew throughout the annual cycle.
Ci sono 1 file riservati su richiesta dell'autore.