What Makes Small Dogs Small?
All domestic dogs descended from grey wolf about 15,000 years ago. Among other land animals, dogs show the greatest variation in size ranging from a size of a Chihuahua to the size of a Great Dane.
What makes them different?
Researchers studied over 3000 dogs from 143 breeds to investigate the genetic basis of size. In the study, they found that a regulatory sequence, called IGF1, on chromosome 15 commonly present in all small breeds but nearly absent in all large breeds. This finding suggests that the IGFI gene determines the small size in dogs.
What is IGF1?
The insulin-like growth factor 1 is protein hormone that plays an important role in promoting growth from birth to adolescence. Researchers found that small dogs share the mutation on IGF1 genes which prevent them from growing large.
What’s the importance of findings?
The findings show that an ancestral small dog with mutation on IGF1 gene was spread geographically through trade and human migration. Due to human preference for smaller dogs (that’s related to the limited living environment in the cities), these small breeds were highly selected and maintained. Human and dogs share 85% of genetic make-up. We also share the same environment with our companion dogs. This research finding sheds light on future research on cancer and other disorders of growth in both human and dogs.
What makes them different?
Researchers studied over 3000 dogs from 143 breeds to investigate the genetic basis of size. In the study, they found that a regulatory sequence, called IGF1, on chromosome 15 commonly present in all small breeds but nearly absent in all large breeds. This finding suggests that the IGFI gene determines the small size in dogs.
What is IGF1?
The insulin-like growth factor 1 is protein hormone that plays an important role in promoting growth from birth to adolescence. Researchers found that small dogs share the mutation on IGF1 genes which prevent them from growing large.
What’s the importance of findings?
The findings show that an ancestral small dog with mutation on IGF1 gene was spread geographically through trade and human migration. Due to human preference for smaller dogs (that’s related to the limited living environment in the cities), these small breeds were highly selected and maintained. Human and dogs share 85% of genetic make-up. We also share the same environment with our companion dogs. This research finding sheds light on future research on cancer and other disorders of growth in both human and dogs.
Photo (left): Great Danes are about 50 times heavier than Chihuahuas!
Source: http://news.bbc.co.uk/1/hi/sci/tech/6531049.stm
Source: http://news.bbc.co.uk/1/hi/sci/tech/6531049.stm
Primary Source:
Ostrander E.A. et. A Single IGF1 Allele Is a Major Determinant of Small Size in Dogs. Science, Vol. 316, Issue 5821. 2007 Apr 6. p.112-115.
Posted by: Olivia Fong
