IBD sharing patterns as intra-breed admixture indicators in small ruminants.

Area of Science:

• Animal genetics
• Population genetics
• Genomics

Background:

• Understanding breed admixture is crucial for livestock conservation.
• Genome fragmentation is expected in admixed breeds due to crossbreeding.
• Identity-by-descent (IBD) patterns can reflect a breed's genetic history.

Purpose of the Study:

• To investigate the relationship between intra-breed IBD patterns and admixture levels in goats and sheep.
• To assess if IBD sharing can serve as an indicator of genetic isolation.
• To highlight the importance of preserving local breeds and their genetic integrity.

Main Methods:

• Analysis of SNP genotypes from 111 goat and 156 sheep breeds.
• Inference of admixture levels using ADMIXTURE software and the AV index (Reynolds' genetic distances).
• Statistical analyses including comparison of means, Spearman correlations, and generalized additive models (GAM).

Main Results:

• Genetically isolated breeds showed a higher proportion of shared IBD segments.
• These shared IBD segments were also found to be longer in isolated breeds.
• A positive correlation was observed between genetic isolation and IBD segment characteristics.

Conclusions:

• Intra-breed IBD segment profiles can effectively indicate a breed's admixture level.
• This research may lead to the development of novel admixture indicators independent of broader genetic landscapes.
• The findings underscore the need for conserving local breeds and their unique adaptive genetic architectures.