In his thesis from the field of population genetics Miika Tapio used molecular markers to study the gene pools of sheep in the Nordic countries, Russia and the Baltics, and studied the variation of mitochondrial DNA in Eurasian sheep.
He analysed 37 northern European sheep breeds by using gene markers inherited from both parents (microsatellites, blood proteins). Tapio examined mitochondrial DNA inherited from only the dam in 76 breeds in an area spanning from northern Europe to the Balkans, the Caucasus and Central Asia. Among other things, the thesis presents a previously undiscovered fourth line of domestic sheep dams that was found in the Caucasus.
The study showed that variation between breeds was clearly greater than typically found in European sheep.
- For example, Finnsheep and Romanov sheep are very different from each other although they are thought to be related, Tapio explains.
Variation between long- and short-tailed sheep was also discovered on the basis of gene markers, but the classification into breed groups only explains a small share of the differences between breeds, as the differences are significant even within breed groups. Gene markers inherited from both parents linked together the breeds that are from adjacent areas.
Diversification of landraces speaks in favour of protection
Northern European native breeds differ from multinational sheep breeds in many ways, forming an important gene pool. So far many native breeds are also less inbred.
- Diversification speaks in favour of keeping the breeds separated in the future as well, Tapio points out.
Northern European landraces are becoming increasingly rare as agricultural production mainly utilises completely different species or multinational sheep breeds.
- Many landraces, such as Finnish Grey landrace, have recently witnessed a significant population decline. The first measures in maintaining sheep gene pools are monitoring the number of animals and avoiding inbreeding with the help of extensive animal registers, Tapio says.
The study determined the protection values of breeds by simultaneously using both within-breed and inter-breed diversity. 19 breeds were assessed to be above others in importance, seven of which are endangered native breeds: Estonian Ruhnu sheep, Finnish Grey landrace, Norwegian Old Spael sheep, Norwegian Grey Troender sheep, Russian Viena sheep, Swedish Dala fur sheep and Swedish Roslag sheep.
Miika Tapio's Doctoral Dissertation "Origin and maintenance of genetic diversity in northern European sheep" shall be examined at the Faculty of Science of the University of Oulu at 12 o'clock on 10.11.2006. The opponent is Dr Michael W. Bruford from the Cardiff School of Biosciences and the custodian is Professor Outi Savolainen from the University of Oulu.
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