Conservation & local programs

Genetic diversity and population structure of the Mexican Creole pig Ts'à¼di Xirgo.

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Abstract

Creole pigs (Sus scrofa) are descendants of pigs, primarily from the Iberian Peninsula, brought by Spanish settlers in the late 15th century. Over the centuries, these pigs have adapted to and naturalized in the diverse local climates, feed resources, and management conditions of the Americas. Creole pigs are considered a reservoir of high genetic diversity and a zootechnical resource with great historical and cultural value, essential for low-density production systems. These animals have exceptional adaptability to different environments. The Ts'à¼di Xirgo pig (DAD-IS FAO, 2025) from the Mezquital Valley, Hidalgo (Mexico), is a local population that illustrates rusticity and resilience. This biotype is maintained for its cultural and gastronomic significance and is distinguished by its adaptation to varied feed sources and maternal capacity under extensive management. In the present study, we analyzed the genetic diversity and population structure of Ts'à¼di Xirgo pigs. Before quality control, 2,134 pigs were included, comprising 41 Creole pigs from four Mexican biotypes and 2,093 pigs from 122 international breeds (Yang et al., 2017). DNA was genotyped using a GGP-50K single nucleotide polymorphism (SNP) chip. The merged dataset contained 26,140 shared SNPs across 1,081 individuals, comprising commercial pigs (n = 418), Creole pigs (n = 138), wild and feral pigs (n = 124), and local pig breeds worldwide (n = 401), including 76 populations showing low FST distances from the Ts'à¼di Xirgo breed. Genetic differentiation was assessed using the fixation index (FST) and clustering analysis (UPGMA dendrogram), while population structure and ancestry were inferred using ADMIXTURE with an optimal K value of 55. As a result, phylogenetic analysis (dendrogram) positioned the Ts'à¼di Xirgo pig in an intermediate branch within the main cluster of domestic breeds (low FST distances, 0.00-0.04). Its moderate genetic differentiation (FST) between 0.02 and 0.03, with close breeds such as the Mexican Mulefoot Pig and Spot Pig (US), suggests a shared evolutionary connection, possibly through American Creole lineages or introgression of genetic material in North America. In addition, population structure analysis (ADMIXTURE, K= 55) revealed an ancestral component predominantly exclusive to the Ts'à¼di Xirgo breed. These findings highlight marked genetic differentiation and very restricted genetic flow in recent generations, reinforcing its identity as a regionally distinct lineage. These results are crucial for informing conservation strategies that aim to maintain population heterogeneity.

Keywords: 2026

How to Cite:

Castro-Roca, C., García-Contreras, A., Loera-Ortega, Y., Alonso-Morales, R., Mendoza-Elvira, S., Medina-González, C., Sierra-Vásquez, Á., Castro-Rosa, G. & Toledo-Alvarado, H., (2026) “Genetic diversity and population structure of the Mexican Creole pig Ts'à¼di Xirgo.”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286234. doi: https://doi.org/10.31274/wcgalp.23887

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