The Joy of Genetics

Ahh, genetics. The mystery game that people either have the ability to solve or live their life completely oblivious to. I prefer those who don't choose the latter. It makes breeding so much easier not having to guess at colors. If you know whats possible and likely it'll be more fun planning for certain colors! I figured I'd do a series post on the basics of genetics and maybe eventually turn them into articles to put on my website. Once you learn the ins and outs of it, you can figure just about any genetic problem out. Its a lot of fun! So lets begin!

All rabbits have a genetic code called a genotype. The physical appearance of the rabbit is called the phenotype. Of course, the genotype directly controls the phenotype.

The 5 genes that I will cover and the genes most commonly used to define a rabbit are as followed:

A series- Determines whether a rabbit is agouti, tan pattern, or self
B series- Determines whether a rabbit is black or chocolate

C series- Determines where and how much color will be on the hair shaft

D series- Determines whether a rabbit is dense or dilute (

E series- Determines how far the color is extended on the hair shaft

A rabbit's genotype is listed in a-b-c-d-e order. There are several other genes including the vienna gene, pattern gene, steel gene, harlequin gene, and modifiers gene.

Let's begin with the A series.

A rabbit is either
(A)- agouti
(at)- tan pattern or
(a)-self.

The dominance of these genes are in that order. A rabbit at the bottom of the dominance list cannot carry anything above it. Also, any gene is said to be recessive to the gene above it. Therefore, tan pattern is recessive to agouti and self is recessive to tan pattern and agouti. Agouti is dominant over tan pattern and self and tan pattern is dominant over self. Self is dominant to nothing and the most recessive gene.This concept works for all the genes.

Every rabbit has two genes from each series. So a rabbit can be:

A(A)- True agouti, does not carry a different -a- gene
A(at)- Agouti carrying tan pattern

A(a)- Agouti carrying self
at(at)- True tan patter, does not carry a different -a- gene

at(a)- Tan pattern carrying self

a(a)- Self carrying self

Because self (a) is the most recessive and cannot carry another -a- gene, a rabbit that is self always has two (a) genes. Therefore, it is always safe to list a self rabbit's genotype as a(a) because there is nothing else it can be.

Now lets talk percentages! You breed a Chestnut (agouti) to an Otter (tan pattern) and you want to know what the odds are for getting agouti or tan pattern. The easiest way to do this is to make a little chart. Let's say we breed a true Chestnut (not carrying any other -a- genes) to a true Otter. The chart would be as follows:

___A___A

at

at

At the top we have the chestnut's two -a- genes and on the side we have the otter's two a genes. Now we fill it in by pairing up the genes from the side and top. The top gene on the left will be paired with the top gene on the side and the bottom gene on the side. The top gene on the right will be matched the same way. Remember to always list the dominant gene first!

___A ___ A

at A(at) A(at)

at A(at) A(at)

Look at that! All of your offspring from this breeding will be agouti carrying tan pattern. So you'd have 100% Chestnuts that are capable of throwing tan pattern. Why? Because each parent had a 'double dose' of their gene so that's all they had to give. What if we took one of these babies and bred it back to their Otter parent. Let's make another chart!

___A ___ at <--- That's the offspring

at A(at) at(at)

at A(at) at(at)

So we can conclude that from this pairing that the odds are 50% of the offspring will be agouti carrying tan pattern and 50% will be true tan pattern.

STOP!

Just because the odds are 50/50 does not mean that if four kits are born that two will be Chestnut carrying tan pattern and two will be Otter. If you've come to this conclusion you need to back up! We are only finding the chance that a color will occur. Out of this breeding the chance that a self rabbit will pop up is zero. The chance that an otter will pop up is 50%. This means you only have two options: Otter or Chestnut. You could get a litter of four and all of them could be Otter. This is very important to remember! Let's make one more chart to wrap up this lesson.

An agouti carrying self and a tan pattern carrying self are bred together. What are the chances of getting each color? In other words, what is the percentage of chance for each color? Chart time!

___A ___ a

at A(at) at(a)

a A(a) a(a)

Wow! That's quite the variety! Let's break it down. In the first block we have agouti carrying tan pattern, the block next to that we have tan pattern carrying self. In box three we have agouti carrying self and in box for we have self. So, what does this mean? It means there is a 50% chance of getting agouti (with 25% being tan pattern carriers and 25% being self carriers), 25% chance of getting tan pattern, and 25% chance of getting self.

So now that you know how to make the charts, go ahead and try it yourself! Stick two -a- genes at the top (In order of dominance! Remember you cannot put a(at) because a self cant carry tan pattern) and two on the sides. Fill in the blanks and tally up the percentages.