Sheep Post-Domestication Expansion in the Context of Mitochondrial and Y Chromosome Haplogroups and Haplotypes

Abstract

Mitochondrial DNA and nonrecombinant parts of Y-chromosome DNA are a great tool for looking at a species’ past. They are inherited for generations almost unaffected because they do not participate in recombination; thus, the time of occurrence of each mutation can be estimated based on the average mutation rate. Thanks to this, male and female haplogroups guide confirming events in the distant past (potential centers of domestication, settlement of areas, trade connections) as well as in modern breeding (crossbreeding, confirmation of paternity). This research focuses mainly on the development of domestic sheep and its post-domestication expansion, which has occurred through human trade from one continent to another. So far, five mitochondrial and five Y-chromosome haplogroups and dozens of their haplotypes have been detected in domestic sheep through studies worldwide. Mitochondrial DNA variability is more or less correlated with distance from the domestication center, but variability on the recombinant region of the Y chromosome is not. According to available data, central China shows the highest variability of male haplogroups and haplotypes.

A 14th century CE Brucella melitensis genome and the recent expansion of the Western Mediterranean clade

“…Our speciation date of B. melitensis is consistent with previously published dates of sheep and goat domestication in the Fertile Crescent [25]. Furthermore, with previous studies indicating that the Western Mediterranean clade diverged during the 4 th or 5 th millennium BCE [26,33] it is likely that B. melitensis arose in the Fertile Crescent and was brought to the Western Mediterranean during the shift from huntergather practices to pastoralism [31,33,35,68].…”

Historical Westward Migration Phases of Ovis aries Inferred from the Population Structure and the Phylogeography of Occidental Mediterranean Native Sheep Breeds

“…The assumed migration phases scenario is presented in Figure 7 c. In fact, the miscegenation of the first phase of the hairy ancestral gene pool, the second phase of the woolly sheep—with firstly coarser and later with finer fleece—and the fat-tailed sheep gene pool, and finally the recent gene flow within this western Mediterranean region, would have drawn the actual Mediterranean sheep’s genetic makeup and participated in the final mosaic genome of the occidental Mediterranean sheep. This three phase introduction assumption is strongly supported by the recent paternal [ 16 , 138 ], maternal [ 16 , 32 ] and genome-wide SNP analysis [ 21 , 33 ].…”

“…The archeological and anthropological analysis highlighted the earliest westward Neolithic human migration that we detailed in the following and faithfully coincided with the proposed scenario for the second wave migration: The first ancestor, from which derived the central Italian APP sheep diverged from the Maghrebian DM breed since 11,000 years ago, would be the first Neolithic sheep migrated by maritime road from the domestication center, reaching South Europe, going through Cyprus, and then the Greece islands to reach the Apennine peninsula—the cradle of the APP breed—where the spread of the earliest Impressa Neolithic group characterized by the sheep breeding dominance at the 9th millennium was revealed [ 16 , 86 , 95 ]. This early Neolithic sheep presence in the Italian peninsula was achieved or reduced probably due to the 8.2 cal ka climatic cooling event and the maximum fire activity noted in this region [ 86 , 95 , 97 ].…”

“…The Mediterranean basin is considered as a main thoroughfare for the maritime diffusion of small ruminant species into South Europe and North Africa [ 5 , 7 , 10 ]. Besides this maritime way, two terrestrial currents were also defined as a way of migration of Neolithic Middle Eastern farmers and their livestock: (i) the Danubian current, which allowed the arrival of breeding in Northern Europe [ 12 , 13 , 14 , 15 , 16 ] and (ii) the Suez Isthmus and/or the South of the Sinai Peninsula allowing the arrival by transhumance in North Africa [ 5 , 8 , 17 ].…”

“…Studying the genetic structure of the early domesticated animal species by the first Neolithic human populations gives valuable insight into the history of modern human populations and their migration routes [ 7 ]. Many studies have provided useful insights into the movement of sheep pastoralism from the domestication center to Eurasia [ 15 , 16 , 18 , 19 , 20 , 21 ]. In addition, the gene flow between American and Near Eastern sheep breeds was explored by Blackburn et al [ 22 ].…”