Re-visiting genetic background of some native Turkish sheep populations: bottleneck and migration

This study aimed to investigate genetic bottleneck effects and migration events among four native Turkish sheep breeds, namely Güney Karaman (GKR), Karakaş (KRK), Kangal (KNG), and Norduz (NRD). After genotyping a total of 120 animals with 28 highly polymorphic microsatellite loci, the genetic bottleneck was assessed by the Wilcoxon test under different mutation models, while population splits and migration events were investigated by the TreeMix algorithm. Wilcoxon sign rank test under the two-phased mutation model (TPM) and the mode-shift indicator based on the distribution of allele frequencies evidenced a lack of genetic bottleneck in four Anatolian sheep breeds. This finding implies that the studied sheep breeds have maintained their effective population size in the recent past. Similarly, the estimated values of effective population size were higher than the number of sampled animals, indicating that they were descendants of ancestral populations with higher sample sizes. The TreeMix algorithm revealed that the NRD was genetically distinct from the other breeds, while there was migration from NRD to KRK and GKR with a rate of 0.0096. The highest migration rate (0.0176) was detected from the KNG to the GKR breed. The results of this study are expected to assist breeders in taking necessary precautions for sustainable production in the future and to facilitate ongoing conservation programs. Indeed, breeders are encouraged to utilize both microsatellites and high-throughput genomic tools such as SNP arrays and next-generation sequencing technologies to foresee the trend in effective population size and genetic bottleneck effects in local sheep populations. Besides, geographic isolation and pure breeding of the NRD breed should be considered in conservation programs to eliminate inbreeding depression and genetic bottleneck in the future.