Genes are funny things. They can hold so much information and mystery at the same time. Look at the amazing staff at Vet HQ. We all have the same basic genes of the human race, but there are small variations that make us the individuals that you can tell apart - different hair - some curly, some straight, some blonde, some brunette; different coloured skin and eyes but we are all people. In dogs and cats that genetic diversity is very obvious too. Think about the dog park and how many different shapes and sizes or breeds of dogs are seen. Each breed looks the way it does because of a combination of genes called a breed signature. Recent studies have enable scientists to identify up to 70 breed signatures for dogs. This information can give us knowledge about what conditions are more commonly associated with a particular breed and hence allow us to be more proactive in prevention and diagnosis. This can be used to avoid breeding animals that have a high risk of certain diseases but also to win a bet!!?? How many times have you heard someone say "I bet you can't tell what breed my dog is?" Genetic testing can now tell you the likely genetic make up of your dog. For the crossbred dog - it can tell you what breed mum, dad and maybe even the grandparents were.
In order to understand how genes combine we must first consider two important concepts. The phenotype is how genes are expressed – that is, how your pet appears when you look at it – does it have brown eyes, long hair, pointy ears or hazel eyes and floppy ears?
The genotype is the combination of genes that make your pet look the way it does. There are dominant and recessive genes. In order to display a particular characteristic your pet either needs two recessive genes (one copy from mum and one from dad) or a single dominant gene (from either mum or dad).
A good example is long hair and short hair dogs. If the gene for long hair is a recessive gene, then both mum and dad must have the long hair gene in order for their puppies to have long hair. This is represented as LxL gives birth to a puppy with the genes L/L. You must have two copies of a recessive gene in order for it to show up.
If the gene for short hair is dominant, then a mating between a long haired dog and a short haired dog will result in a short haired dog. L x S gives birth to a puppy with the genes L/S. Even though a long hair gene is there, it is recessive. The dominant or short haired gene will be the only one on show.
If a short haired dog mates with a short haired dog S X S the puppy produced will have the genes S/S and have short hair.
It starts to get complicated when a dog has a mixed gene pattern mates with another dog with a mixed gene pattern. Remember is the dominant gene that creates the overall “look” or the phenotype.
L/S (shorthaired mixed gene mum) x L/S (shorthaired mix gene dad) will have the chance to give birth to a puppy with one gene from mum and one from dad. The resulting puppies may have :
- L/L (long haired puppy) remember it takes two recessive genes to show up
- L/S (short haired puppies of mixed genes) remember when there is both a dominant and a recessive gene- only the dominant one shows
- S/S (short haired puppy)
It is this complicated mix between dominant and recessive genes that can lead to the most bizarre family trees.
"I bet you can’t tell me what breed Timmy is?"
Recently a DNA test was performed on Timmy. The test is called a BITSA test and this stands for Biological Identification Through Scientific Analysis.
A cheek swab was taken and Timmy’s heritage was identified.
bitser n Colloq
1. a mongrel 2.an animal of mixed stock …Macquarie dictionary