Authors:

Shayden Jones

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About Paper:

The objective of this research aimed to assess the genetic diversity of Australian Merinos and Merino de Rambouillet breeds, which originated from the Spanish Merino breed and underwent genetic isolation due to their separation in the 1700-1800s. The datasets used for this research were obtained from the Widde Database (http://widde.toulouse.inra.fr/widde/), genotyped using OvineSNP50, for single nucleotide polymorphisms(SNPs), and after QC included samples from 50 Australian Merino, 102 Rambouillet, and 20 Spanish Merino sheep used for historic comparison. These datasets were analyzed using PLINK software and RStudio. The genomic diversity analyses performed included principal component analysis(PCA), genomic inbreeding, runs of homozygosity(ROH), linkage disequilibrium, and effective population size. The PCA clearly differentiated the Australian Merino and Rambouillet populations, while also showing a closer association of Spanish Merino sheep to both populations. Genomic inbreeding was lower in the Merino breeds compared to other livestock populations, with average values of 0.0276 for Rambouillet, 0.0209 for Australian Merino, and 0.0543 for Spanish Merino. Runs of homozygosity (ROH) analysis using 1,586 ROHs from Rambouillet and 505 ROHs from Australian Merino revealed concentrated ROH regions on the first six chromosomes for both breeds. The average of linkage disequilibrium across all markers was 0.06 for the Australian Merino breed and 0.07 for the American Merino de Rambouillet breed, indicating that genomic selection would be equally feasible in both populations. In conclusion, our preliminary results indicate that geographical separation and differential selection strategies in worldwide Merino populations have made them genetically distinct breeds with prominent levels of genetic diversity.

Source:

Purdue University / 2023

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Co-authors:

Shayden Jones