Urbanisation and the genetic structure of Passer italiae (Vieillot 1817) populations in the South of Italy

Abstract

Sparrows have colonized areas modified by humans since the onset of agriculture and seed storage. In fact, present day distributions of the sparrow populations are directly related to urban areas, farms and villages. Consequently the sedentary behaviour of sparrows, in pristine areas, with low densities of specimens, can act as a barrier to gene flow among populations. We analyzed the genetic variability and gene flow rates in four Italian sparrow populations sampled in areas affected by different levels of human activity. Population variability was analyzed by DNA fingerprinting with M13 multilocus minisatellite probe, which yielded multibanded fingerprints (the average number of bands was 25, ranging in size from 23 kb to 0.3 kb). The population located within the pristine area of the Cilento-Vallo di Diano National Park (San Marco) showed the higher value of within-population similarity (Sw = 0.73). This suggests a probable higher level of inbreeding in comparison with the other localities. The genetic isolation of the San Marco population is also imputable to the between-populations similarity values (Sb), that seem to be related with a preferential direction of gene circulation along urbanised corridors. The results show that population variability and gene flow rate in the Italian sparrow are directly related to the presence of urbanised areas. The results also show that the M13 multilocus fingerprinting probe represents a advantageous marker for the detection of genetic variability within a small geographical scale in passerine birds.