Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2025
Publication Date: 5/13/2025
Citation: Spetter, M.J., Utsumi, S.A., Armstrong, E.M., Rodriguez-Almeida, F.A., Ross, P.J., Macon, L.K., Jara, E., Cox, A., Perea, A.R., Funk, M., Redd, M., Cibils, A.F., Spiegal, S.A., Estell, R.E. 2025. Genetic diversity, admixture, and selection signatures in a Rarámuri Criollo cattle population introduced to the Southwestern United States. International Journal of Molecular Sciences. 26(10):4649. https://doi.org/10.3390/ijms26104649.
DOI: https://doi.org/10.3390/ijms26104649

Interpretive Summary: Rarámuri Criollo are a biotype of cattle from the Copper Canyon of Mexico that are well adapted to harsh conditions. This biotype was introduced to the USDA-ARS Jornada Experimental Range to evaluate their suitability for beef production in desert conditions of southern New Mexico. Research showed that they were, well adapted to arid rangelands with low forage production and the hot climate. However, the genetic characteristics of this unique gene pool are not well understood. Genetic analyses were conducted to examine the relatedness of this biotype to other Criollo biotypes from North and South America. These analyses revealed that the Rarámuri Criollo biotype is a unique genetic resource that is distinct from other biotypes of Iberian ancestry. The genetic signatures represented traits associated with desirable production traits, including growth, meat and carcass, and reproduction. Results indicate that this biotype could be used to improve beef production in harsh desert conditions its preservation is crucial to those efforts.

Technical Abstract: Rarámuri Criollo (RC) cattle have been raised by the isolated Tarahumara communities of Chihuahua, Mexico, for nearly 500 years, mostly under natural selection and minimal management. RC cattle were introduced to the United States Department of Agriculture-Agricultural Research Service Jornada Experimental Range (RCJER) in 2005 to begin evaluations of beef production performance and their adaptation to the harsh ecological and climatic conditions of the Northern Chihuahuan Desert. While this research unveiled crucial information on their phenotypic plasticity and adaptation, the genetic diversity and structure of the RCJER population remains poorly understood. This study analyzed the genetic diversity, population structure, ancestral composition, and selection signatures of the RCJER herd using a ~64 K SNP array. The RCJER herd exhibits moderate genetic diversity and low population stratification with no evident clustering, suggesting a shared genetic background among different subfamilies. Admixture analysis revealed the RCJER herd represents a distinctive genetic pool within the Criollo cattle breeds, with significant Iberian ancestry. Selection signatures identified candidate genes and quantitative trait loci (QTL) for traits associated with milk composition, growth, meat and carcass, reproduction, metabolic homeostasis, health, and coat color. The RCJER population represents a distinctive genetic resource adapted to harsh environmental conditions while maintaining productive and reproductive attributes. These findings are crucial to ensuring the long-term genetic conservation of the RCJER and their strategic expansion into locally adapted beef production systems in the USA.