The mention of the word Genetics, is often enough to make anyone outside of the science community shudder. However for those of you that what to take your reptile passion to the next level and begin breeding you’ll find it very helpful to know some of basic mechanics behind genetics as well as the general terms used within this subject. Our goal with this article is simply to introduce you to some of the basic element and how they apply to reptiles.
Many genetic words are used extensively in reptile lingo and so we thought the best place to start would be with a basic definition of many of these frequently used terms:
Some examples of supers would be the: super snow leopard gecko, super hypo boa and super pastel ball python. Any time that a super is bred to a normal wild type then all of the offspring will show the het homo form of the super. So in leopard geckos all snows will be produced, in boas all hypos will be produced and in balls all pastels will be produced. The super form in any way is a great addition to a breeding group as it opens up a whole new way to create new morphs when crossed with other genetically proven animals.
Genetics is all about how traits get passed down from one generation to the next. From the terms above you can see that it is not as simple as just looking at the traits a reptile may display because they also can carry underlying traits/genes that they will pass along to their offspring. A basic knowledge of how dominate and recessive genes work will take you a long way in understanding and developing selective breeding projects.
When two animals reproduce they “send” half of their DNA (genetic makeup) to their offspring. Every animal has two copies of each gene they carry, one inherited from the father and one from the mother. The best genetic tool for helping to understand how genes are passed along is the Punnet square. This square uses the genes each parent carries to calculate the combinations of genes for the offspring.
To illustrate we will use two different examples using the recessive gene of albino and the dominant gene of wild type. Remember for the recessive gene to be displayed, the offspring must inherit a copy of the gene from both parents. However even though a gene may not be displayed it can still be passed along to the offspring.
Mother displays albino and carries a double albino gene (A,A). Father displays wild type and carries a double wild type gene (WT,WT).
In the Punnet squares below, albino will be displayed by “A” and wild type by “WT”.
The results of this pairing will result in all offspring displaying the wild type characteristics but will also carry or be het (heterozygous) for the albino gene.
For this example let’s take two of the offspring from above and breed them together. Both parents display wild type but are het for albino so they each carry one wild type gene and one albino gene (WT,A).
The results here are:
Here’s where it gets even more interesting, given there is no cost effective way of identifying which animals are in fact het for albino and which ones are homozygous wild type, the normal looking offspring will be called 66% het for albino. Purchasing an animal from this group would give you a 66% chance of having an animal that carries the albino gene, which is called het albino.
The Punnet square is an excellent tool for understanding the potential combinations and theoretical percentages of a breeding pair. However, we can’t forget the role of Mother Nature, some times the percentages work out close to what science tells us and other times they can be very different. One way to think of it would be to imagine a bucket filled with 50 red marbles and 50 blue marbles. If you only took 4 marbles out you could end up with 4 red or 4 blue. It’s the same with genetics, if you produce a smaller amount of babies you could end up with “all the same color” meaning that you could get lucky and get all the visual morphs or you could get none.
Selective breeding projects have become increasingly more complex with reptile breeders combining multiple genetic traits. By doing this the Punnet square increases both in size and in the potential possibilities. These breeding programs can often take many years for the visual genetic traits to be visually produced. Patience and meticulous record keeping is required but the results are one of the most exciting and dynamic aspects of breeding reptiles today. Waiting to see what combination of genetics is going to be displayed in each new hatchling is simply an amazing experience.