Inferring the population structure of the Maghreb sheep breeds using a medium-density SNP chip

Area of Science:

• Animal Genetics
• Population Genomics
• Sheep Breeding

Background:

• North Africa boasts diverse indigenous sheep breeds shaped by regional history and environment.
• Limited genome-wide studies exist on North African sheep population structure.

Purpose of the Study:

• To analyze the genetic structure and admixture patterns of six Maghreb sheep populations.
• To compare these populations with global sheep and mouflon using genomic data.

Main Methods:

• Utilized the Illumina 50K Ovine BeadChip for genome-wide analysis.
• Employed multiple analytical methods to assess population structure and admixture.
• Compared six Maghreb sheep populations against 22 global sheep and mouflon populations.

Main Results:

• Observed widespread hybridization events, resulting in heterogeneous genetic architectures across North African breeds.
• The Barbarine breed displayed low genetic heterogeneity and significant Southwest Asian ancestry, supporting an Asian origin for fat-tailed sheep.
• Substantial Merino introgression (15-31%) was detected in other breeds, alongside evidence of admixture with southern European sheep.
• Identified opposing ancestry gradients between North Africa and Central Europe (Southwest Asian and Central European).

Conclusions:

• North African sheep populations exhibit complex admixture patterns, influenced by historical gene flow.
• Evidence supports both Asian origins for some breeds and European introgression in others.
• The study underscores the high degree of gene flow in global sheep populations and recent admixture within North Africa.