Sheep: evolution's 'animal stars'

Not kidding ewe! Sheep are stars amongst domestic animals for their vast genetic diversity. Photo / Thinkstock
Not kidding ewe! Sheep are stars amongst domestic animals for their vast genetic diversity. Photo / Thinkstock

An international study has shown sheep have evolved with more genetic diversity than dogs or cows.

An international research team has mapped the ancestry of sheep over the past 11,000 years and has revealed that the woolly creatures are stars amongst domestic animals, with vast genetic diversity and substantial prospects for continued breeding to further boost wool and food production.

The study, published in the online, open-access journal PLoS Biology, maps out how humans have moulded sheep to suit diverse environments and to enhance the specialised production of meat, wool and milk.

By detailing sheep domestication and migration patterns across the globe, the research also supports and adds to the current knowledge of human movements throughout history.

Lead author Dr James Kijas from the CSIRO said the team traced the relatedness between nearly 3000 sheep by comparing 50,000 DNA sites across the genome, and pinpointed the genetic consequences of domestication and subsequent division of sheep into hundreds of breeds.

He said the detailed gene map showed that sheep breeds have been formed in a 'fluid' way that makes them different from other species of domestic animals.

"Frequent mating and strong gene flow between animals of different breeds has ensured that most modern sheep breeds have maintained high levels of genetic diversity, in contrast to some breeds of dogs and cattle that generally have higher levels of inbreeding," Dr Kijas said.

He said the genetic diversity meant sheep breeders could expect strong improvements in important production traits that could play a part in feeding the world's growing population.

Dr Kijas said the extensive DNA sampling, encompassing 74 sheep breeds, would act as a touchstone for livestock research for years to come, including studies of genetic diversity to better manage the conservation of threatened breeds.

The research was facilitated and coordinated through the International Sheep Genomics Consortium.


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