La biodiversità della transumanza

The genetic diversity of transhumant breeds and landscapes. Transhumance has been among the most effective Pastoralists’ adaptation strategies, fostering the selection of the most suitable animals for hardiness, easy management, grazing ability, and resilience- crucial traits for migration. In Italy, the widespread seasonal droving of livestock along steady routes since centuries (e.g., Tratturi in the southern regions or Alpage in the northern areas ) shaped several cattle, sheep, and goats breeds and ecosystems and contributed to the exceptional livestock biodiversity richness of our Country. Today, in light of the ongoing climate change and the importance of safeguarding the ecosystems, the conservation of livestock genetic variability and the understanding of the genetic basis of its adaptation to the natural environment, breeding conditions, and management strategies they have been subjected to is strategic. Italy counts about 16 breeds of cattle and more than 50 local and autochthonous sheep and goats officially acknowledged by the Ministry of Agriculture, many traditionally bred by transhumant small ruminant herders or mountain farmers. Here, we show the pattern of genetic diversity within and among the local transhumant breeds at the DNA level by analyzing Runs of Homozygosity (ROH) and the pasture botanical composition of some migration passages as an indicator of landscape ecosystem conservation grade. The analysis of Runs of Homozygosity (ROH), genomic regions with identical haplotypes haplotypes inherited from each parent, sheds light on population history, estimate the genomic inbreeding, deciphers the genetic architecture of complex traits and diseases, and helps in identifying genes linked with agro-economic traits. For example, among five Italian dairy and beef cattle breeds, the highest number of short ROH (related to ancient consanguinity) was found in the Piedmontese, followed by Simmental, a dual purpose largely used to exploit summer mountain pastures along all of the Alpine Arch. Conversely, the Italian Brown and Holstein had a higher proportion of longer ROH distributed across the whole genome, revealing recent inbreeding. Among the sheep autochthonous breeds, Bergamasca appeared as the less inbred. The Bergamasca sheep breed is raised traditionally by transhumant management in Lombardy. The ROH analysis in goats revealed an opposite pattern between Northern and Southern breeds. The NRD populations, bred in isolated valleys, present more and shorter ROH segments. In contrast, the CSD populations have fewer and longer ROH, likely due to frequent admixture events during the horizontal transhumance practice followed by a more recent standardization. As an example of vegetational biodiversity linked to transhumance, theeventi longitudinal analysis of the pasture composition of two mountain grazing sites located in the North-Western Italian Alps exploited in sequence by transhumant cows allowed the recognition of five vegetation types and seven vegetation sub-types. How the fine knowledge of animal and pasture biodiversity could support the conservation of transhumance practices is discussed.