Monday, July 4, 2016

New Zealand Rabbit Genetics: Dominant And Recessive Gene's

Just as in humans, a rabbits chromosomes are strings of DNA that act as building blocks or blueprints that determines the final characteristics or traits of the animal. Each chromosome has an individual spot or location (loci) in which a specific gene is attached. When two chromosomes combine together they form a chromosomal pairing in which each chromosome supplies one gene to make a genetic pair. These gene pairings then act together, alone or in combination with other genes and modifiers to determine a rabbits overall coat and hair appearance. To be more accurate, each gene is further categorized by it's specific function or property known as alleles (which are different versions of the same gene). So for the remainder of these three articles we will refer to the individual gene's variations as alleles.

This is of course a pretty basic statement, and you could examine the structure of DNA and chromosomes until your eyes glaze over, but suffice it to say all you need to know is that both the buck and the doe each contribute one chromosome to their offspring. These chromosomes when paired together each supply one part of a gene (allele) pair that individually or in combination with other allele's determine their offspring's appearance (body shape, ear size, coat color and patterns etc…). Before we get into the second article in this series, you need to understand a few terms as well as understand how the gene's allele's when paired together work to determine your rabbits final coat color and pattern characteristics.

First of all, every allele is classified as either 'dominant' or 'recessive'. For scientific notational purposes all allele's classified as dominant are represented by a capitol letter, while their recessive counterpart(s) are represented by a uncapitalized letters. A dominant allele is just that, it dominates the pairing. For any pairing in which there is at least one dominant allele, the characteristics of that dominant allele almost always supersedes those of the recessive allele. Most dominant allele's express themselves completely suppressing any characteristics of the recessive allele. When this happens it is called complete dominance. However, recessive allele's can modify the expression of the dominant allele making subtle changes to the overall genetic outcome. When this happens to relationship of the dominant allele in regards to the recessive allele is called incomplete dominance. In addition, an allele pair can be made up of two recessive allele's which may produce a totally different outcome.

So what exactly does all this dominant and recessive gene mumbo jumbo mean? To keep it simple, a rabbits dominant allele traits are visually apparent over a recessive allele. That means you can see them when you look at the rabbit. A rabbit's recessive allele traits are not visually apparent. That means the characteristics of the allele are there, but you cannot visually see them.

As a quick example of how gene dominance works we are going to examine the B-series gene whose allele pairings are responsible for producing black, blue (we will discuss blue coloring in our second article), and brown hair colors in rabbits. When it comes to color, almost all rabbits will carry either the black or brown allele.

There are only two B-series gene allele's black or brown. The combination of these two allele's determine whether the rabbits base coat color is going to be black or brown. Since black is the dominant allele in this pair it is represented by the capitol letter 'B', because brown is the recessive allele in this pair it is represented by the uncapitolized letter 'b'. As the B-series gene is made up of a combination of these two dominant and or recessive alleles, when writing them we indicate the dominant black allele as (B_), and the recessive brown allele as (b_). We use the '_' to denote the second allele which is absent in a paring when we do not know what it is yet.

As mentioned earlier, the buck and the doe each supply one chromosome to their offspring to complete the chromosome's genetic pairing. As the B-series gene has only two allele's black (B_) and brown (b_) there are only three possible allele combinations. Their offspring can have two dominant black allele's (BB), one dominant black allele and one recessive brown allele (Bb), or two recessive brown allele's (bb). Because black (B_) has complete dominance over brown (b_), any combination of these allele's in which there is at least one black allele (BB, or Bb) will result in black offspring. When two recessive brown (b_) alleles complete the pair (bb) then the offspring will be brown.

Terms Or Definitions

Alleles: Are different versions of the same gene that can occupy the same position on a particular chromosome and control the same characteristic such as hair or eye color. Rabbits are diploid organisms because they have two alleles, one at each genetic locus, with one allele inherited from each parent. In our previous example, we examined the B-series gene that could made up of pairs of either black (B_) alleles, brown (bb) alleles or a combination of the two.

Chromosome: A string of DNA made up of individual points (or loci) called genes. Rabbits cells contain two sets of chromosomes, one set inherited from the mother (doe) and one from the father (buck). These chromosomes combine together to make pairs in which they share genes.

Genes: Are the working subunits of DNA. They hold the blueprints or genetic instructions that determine the rabbits genetic makeup (body size, composition, hair color etc.) Genes come in multiple variations called allele's which make up the gene pairing.


This is just a quick example to show you how a chromosome's genes (and all it's allele variants) work together to determine one color aspect of your rabbits potential coat color. Now that you understand the 'lingo' it's time to look at are second article 'New Zealand Rabbit Genetics Part 2: Hair Color: It's In The Genes' for in in depth look at how to determine the color characteristics of your breeding rabbit's and what to expect when you breed specific color combinations of New Zealand Rabbits. I know there may be a lot of new terms that many people are not familiar with when it come to genetics and I will try and keep this information as simple as I can. Maybe the following line drawing will make my ramblings more clear. As always, if you have found this article interesting or informational please share it with your friends. Don't forget to follow us on Facebook or on Google+ for the latest articles on our blog related to raising your own meat rabbits.

In a nutshell:

Two individual chromosomes, each come from each parent.
  • These chromosomes combine to make one chromosomal pair in the offspring's cells.
    • This chromosome pair Is made up of multiple genes (A, B, C, D, etc…)
      • These genes are made up of individual genetic variations called allele's.
        • The allele's of the B-series gene that we examined in this article were black (B_) and brown (b_).

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