Low mitochondrial diversity in native Italian pig breeds is consistent with the occurrence of strong population bottlenecks

Abstract

In this study, we have analysed the variation of 81 Italian pigs from the Calabrese, Casertana, Cinta Senese, Sarda and Nero Siciliano breeds as well as 54 Italian wild boars by using a dataset of mitochondrial control region sequences generated by us and others. Diversity parameters were rather low in Italian native pigs, with haplotype and nucleotide diversities ranging between 0.35-0.79 and 0.0013-0.0061, respectively. This result is consistent with the strong population bottlenecks that traditional Italian breeds have suffered due to competition with more productive foreign pig varieties. Moreover, median-joining network analysis showed that the majority of Italian pig sequences are distributed in two main clusters and that all of them belong to the E1 haplogroup. Conversely, Italian wild boars were more diverse than their domestic counterparts and they harboured the E1 and E2 haplogroups. The absence of the E2 haplogroup in Italian pigs and its moderate frequency in wild boars might suggest that this haplogroup was rare at the time that wild boars were domesticated in Italy.