Genetic characterization of sheep breeds in Egypt and Italy

Project leaders

Lorraine Pariset, Othman El Mahdy Sayed Othman

Agreement

EGITTO - ASRT - Academy of Scientific Research and Technology

Call

CNR/ASRT 2011-2012

Department

Agriculture and Food

Thematic area

Biology, agriculture and food sciences

Status of the project

New

Research proposal

The earliest archaeozoological evidence for domestic sheep comes from a restricted area of southwestern Asia: modern Iran, Turkey, and Cyprus (Vigne et al 2003). A pioneering genetic study examining karyotypes of extant wild sheep species (Nadler et al 1973) showed that Italian domestic sheep derived from the Asiatic mouflon (O. orientalis) of Anatolia, Western Iran and southwest Iran. Egyptian sheep derived from North Africa in the coastal Mediterranean zone, Northern Syria and Southern Turkey (Ghanem, 1980). Both archaeozoological and genetic evidence indicate that sheep domestication occurred 10000-1000 years ago. In the following millennia, domesticated sheep were spread rapidly into different regions. Subsequently, sheep populations developed after selective breeding for desirable traits and environmental tolerance. Since domestication, sheep have established a wide geographic range due to their adaptability to poor diets and extreme climatic conditions and their manageable size.
Archaeological evidence indicates a spread of the taxa out of the Near East and across Europe, either through the Danube valley or along the Mediterranean coast. The first appearance of the remains of domestic sheep in western Mediterranean Europe (approx. 5400 BC) is believed to reflect a rapid spread by sea (Tapio et al 2006; Pereira et al 2006). Transport of livestock by sea and/or along Mediterranean coastal regions was operated by Phoenicians, Greeks, Romans, and Berbers. Italy and Egypt were crucial zones for breeds migration and formation. Italy has a great historical relevance, having hosted Greek, Etruscan, Romans, and even Arabic civilizations. In Egypt, sheep first entered via Sinai and migrated down Africa (Ghanem, 1980).

The genetic history of sheep was investigated using three major sources of genomic variation: nuclear genome, Y chromosome and mitochondrial genome. The analysis of the non-recombining region of the Y chromosome revealed patterns of male mediated introgression during breed development (Meadows et al 2006). Recent surveys tested animals from southern and northern Europe (Lawson et al 2007) or Europe and Middle East (Peter et al 2007) using microsatellites and enabled the analysis of genetic partitioning at a continental scale. Interestingly, southern European breeds displayed increased genetic diversity and decreased genetic differentiation compared with their northern European counterparts. This is consistent with the expectation that high genetic diversity is maintained close to the center of domestication, and decrease with increasing geographic distance. Kijas et al (2009) used a SNP panel to analyze sheep nuclear genome, providing  indication that breeds cluster into large groups based on geographic origin and that SNPs can successfully identify population substructure within breeds. A recent study of retrovirus integrations (Chessa et al 2009) indicated an early arrival of the primitive sheep populations (European mouflon, North-Atlantic Island breeds) and a subsequent advent of wool producing sheep. Mitochondrial sequencing was used to explain the origins of many modern livestock species. Sheep data are beginning to match the pattern observed in other domestic species, even if the sheep haplogroups hardly correlate with geography. The existence of multiple mtDNA lineages and their mixing within breeds (Pedrosa et al 2005; Meadows et al 2005, 2007; Pereira et al 2006) could be due to multiple domestication events and subsequent human selection or to introgression between domestic and wild species. Five lineages were identified in sheep (Meadows et al 2007). The main haplotypes A and B are both found in Asia, while B dominates in Europe. Haplotype C was found in Portugal, Turkey, Caucasus and China (Tapio et al 2006). Haplotype D is present in Rumanian Karachai and Caucasian animals.

Threats to biodiversity are increasing in terms of extinction rate, destruction of ecosystems and habitat or loss of genetic diversity within the species utilized in agriculture. The modern breed concept during mid-1800s caused remarkable changes in the livestock sector: large-scale production expanded (Porter 2002) and led to the formation of well-defined breeds, exposed to intense anthropogenic selection. Consequently, farmers substituted less productive, locally adapted, native breeds with highly productive cosmopolitan breeds and progressively abandoned marginal areas (Taberlet et al 2008). According to FAO (2007) 20% of the breeds world-wide are classified as critically endangered, critical-maintained, endangered or endangered-maintained. The number of threatened sheep breeds is 84 out of 618 recorded. It is likely that a high number of breeds are being and will be lost in the near future, before their characteristics and potential can be studied and evaluated, due to rapid climate change, increasing market demand and human demographic expansion (FAO 2008). To ensure a prompt response to the needs of future generations  preserving as much the farm animal diversity as possible is needed.
References:
Bunch et al 1976 Cytogenet Cell Genet 17:122-136
Chessa et al 2009 Science 324:532-536
Ghanem 1980 Encyclopedia of Animal Wealth
Kijas et al 2009 PLoS ONE 4:e4668
Lawson et al 2007 Heredity 99:620-631
Meadows et al 2007 Genetics 175:1371-1379
Meadows et al 2006 Anim Genet 37:444-453
Meadows et al 2005 J Hered 96:494-501
Nadler et al 1973. Z Saeugetierkd 38:109-125
Pedrosa et al 2005 Proc R Soc Lond B 272:2211-2217
Pereira et al 2006 Mol Biol Evol 23:1420-1426
Peter et al 2007 Anim Genet 38:37-44
Porter 2002 CABI Publishing, Wallingford, UK
Taberlet et al 2008 Mol Ecol 17:275-284
Tapio et al 2006 Mol Biol Evol 23:1776-1783
Vigne et al 2003 Bull Corr Hell Suppl 43:239-251

Research goals

mtDNA studies are used in molecular evolution, classification, population genetic analysis, relative identification, forensic judgment, aging, disease diagnosis, apoptosis and quantitative traits loci (QTL) (Albuquerque et al 1998; Wallace 1999; Gray et al 1999; Sutovsky & Schatten 2000).
mtDNA analysis of Italian and Egyptian sheep breeds will gather information on sheep history that led to modern breeds in both countries. Results would have also relevance to considerations of biodiversity and conservation. Data would then be helpful to the improvement of breeding and to the characterization of typical products, so the results of the project would be supportive to the local economy in both countries.

The project -using mtDNA sequencing analysis- is aimed to:
(1) Detect of genetic biodiversity within and between different sheep breeds in Egypt and Italy.
(2) Clarify the origin of modern breeds in both countries
(3) Develop and optimize conservation genetic management of Italian and Egyptian sheep biodiversity for the foreseeable future.
So far, no mtDNA data on Italian or Egyptian sheep breeds have been published. This project proposes using mtDNA sequencing analysis to develop and optimize conservation genetic management of Italian and Egyptian sheep biodiversity for the foreseeable future.
 
Albuquerque et al 1998 J Dairy Sci 81:544-549
Gray et al 1999 Science 283:1476-1481
Wallace 1999 Science 283:1482-1488
Sutovsky & Schatten 2000 Int Rev Cytol 195:1-65

Last update: 18/06/2025