Tuesday, 15 May 2012

A Study of Nasty and Nice Lab Rats Makes an Interesting Breakthrough for Genetics.

Dogs are considered a man's best friend but at some point in history they were all wolves. "When you compare a dog with a wild wolf, a wolf has no interest in communicating with or tolerating humans. If you're lucky, a wolf in the wild wouldn't care about you. But a dog does care and they even seek human presence." (Bryner, 2009). In fact this is what separates all domesticated animals from their wild ancestors. But what causes this behaviour?
"A study of nasty and nice lab rats" (Bryner, 2009) has provided an interesting breakthrough in the genetics of tameness. The study has allowed scientists to discover a set of genetic regions that are considered responsible for tameness.
This experiment began in 1972 when a group of Russian scientists captured a single population of rats from the wild. They conducted what they called the "glove test" to measure the rats level of tameness/aggression. This involves observing the rats behaviour when they are confronted with an approaching human hand and attempted to be handled.
The results of the "glove test" were used to separate the population into two distinct groups. One that showed increased aggression towards the hand, for example screaming and attacking/biting, and the other with reduced aggression. The scientists then bred the best behaved rats together and most aggressive rats together for over 60 generations, by which time the "tame" rats were completely unafraid of humans; when put through the glove test they tolerated handling, being picked up and some even approached the hand in a non-aggressive manner. By contrast, the "aggressive" group would fiercely attack the hand or scream and try to escape.

The scientists then bred a selected number of the tamest rats with aggressive ones and then interbred the resulting offspring. The purpose of this was to produce rats that had a mix of both tame and aggressive alleles. The genomes of these rats were then typed using over 200 genetic markers that covered most of the genome. This allowed them to identify the regions of genetic material responsible for tameness because if two rats had matching genes in a particular region of their genome but one was tame and the other aggressive, they could rule that section out as responsible for tameness (and vice versa). Through this method the scientists managed to find two significant regions responsible for tameness.

Although they have identified two regions that play a role in tameness, these regions consist of over 1000 single genes. Because of this the studies are ongoing. Scientists breed two new generations of rats every year which are used for further testing and will hopefully lead to the uncovering of exact genes linked with certain rat behaviours.

The significance of finding the exact genes would be quite large; not only will it help animal breeders and handlers to better understand why some species interact with humans better than others, but it could also lead to the development of precise breeding strategies to pass these genes through generations as a method of producing tame animals.  The scientists involved hope that the results of their study will eventually allow humans to domesticate species that were once believed to be untameable such as the wild African Buffalo. This would be highly advantageous in providing food for the earth's ever growing population.

So theoretically, in the not too distant future, that life-long dream of owning a tiger could become a possibility, and I don't mean by buying a "toyger cat"  the "glittered new designer breed  of domestic cat, reminiscent of a toy tiger." (Toyger Cat Society, 2000-2011)
References:
Albert, F. W., Carlborg, O., Plyusnina, I., Besnier, F., & Hedwig, D. (2009, June). Genetic Architecture of Tameness in a Rat Model of Animal Domestication. Genetics 182.2 , 541-54.
Bryner, J. (2009, June 10). Genetic Difference Found in Wild vs. Tame Animals. Retrieved March 17, 2012, from LiveScience:   http://www.livescience.com/

 Toyger Cat Society. (2000-2011). The Toyger Cat. Retrieved March 19th, 2010, from The Toyger Cat: http://www.toygers.org/
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