On the origins of American Criollo pigs: A common genetic background with a lasting Iberian signature.

American Criollo pigs are thought to descend mainly from those imported from the Iberian Peninsula starting in the late 15th century. Criollo pigs subsequently expanded throughout the Americas, adapting to very diverse environments, and possibly receiving influences from other origins. With the intensification of agriculture in the mid-20th century, cosmopolitan breeds largely replaced Criollo pigs, and the few remaining are mostly maintained by rural communities in marginal areas where they still play an important socio-economic and cultural role. In this study, we used 24 microsatellite markers in samples from 1715 pigs representing 46 breeds with worldwide distribution, including 17 American Criollo breeds, with the major focus of investigating their genetic diversity, structure and breed relationships. We also included representatives of the Iberian, Local British, Hungarian, Chinese and Commercial breeds, as well as Wild Boar, in order to investigate their possible influence in the genetic composition of Criollos. Our results show that, when compared with the other breeds, Criollo pigs present higher levels of genetic diversity, both in terms of allelic diversity and expected heterozygosity. The various analyses indicate that breed differentiation overall explains nearly 21% of the total genetic diversity. Criollo breeds showed their own identity and shared a common genetic background, tending to cluster together in various analyses, even though they differ from each other. A close relationship of Criollos with Iberian breeds was revealed by all the different analyses, and the contribution of Iberian breeds, particularly of the Celtic breeds, is still present in various Criollo breeds. No influence of Chinese breeds was detected on Criollos, but a few were influenced by Commercial breeds or by wild pigs. Our results confirm the uniqueness of American Criollo pigs and the role that Iberian breeds have played in their development.

Ex situ and in situ data for endangered livestock breeds in Spain.

Improvements in ex situ storage of genetic and reproductive materials offer an alternative for endangered livestock breed conservation. This paper presents a dataset for current ex situ collections and in situ population for 179 Spanish livestock breeds of seven species, cattle, sheep, pig, chicken, goat, horse and donkey. Ex situ data was obtained via survey administered to 18 functioning gene banks in Spain and relates to the reproductive genetic materials (semen doses) of 210 livestock breeds distributed across the gene banks. In situ data combines CENSUS information with linear regression techniques and relates to the geographic distribution of 179 Spanish autochthonous livestock breeds (2009-2018), and in situ population projections and extinction probabilities (2019-2060). We use a decision variable defining an "acceptable level of risk" that allows decision makers to specify tolerable levels of in situ breed endangerment when taking ex situ collection and storage decisions.