Selective Breeding
We left Step 1 knowing how to capture chickens, how to learn and understand their DNA, and what traits to look for to get started on our chicken empires. Now, we will take our first look into expanding our flock through Selective Breeding in a Private Coop. But first, it's time for everyone's favorite segment:
Let's Talk Genetics
It is a great time to freshen up on Punnett squares
The key to making resource-producing chickens is to selectively pass down recessive traits in your chickens. In order to do that, you'll need to know how breeding works and the probabilities involved in it.
When two organisms sexually reproduce, each parent donates half of its DNA to the child. These half strands of DNA are made up of one of the two alleles in each gene from each parent. For homozygous genes, this does not affect anything because there is a 100% chance that the allele passed on will have the same dominance as the gene. However, in heterozygous genes, this means that the parent will have a 50% chance to pass on the dominant allele and a 50% chance to pass the recessive. Setting up a Punnett square can help to visualize the possible outcomes and their relative liklihood.
As it Relates to GCE
In GCE, recessive genes are typically what you will be most concerned with. You
will want to breed chickens that share a heterozygous gene to make chickens
that are recessive in that trait. To best explain this, let's look at an
example. Let's say you would like to have a coal chicken (bbccDDFFSSWW) to
help alleviate the slog of mining 8 stacks of coal to make a single Carbonado.
All you have, however, are two feather chickens: one chicken is BbCCDDFFSSWW,
and the other is BBCcDDFFSSWW. Although it may take some effort, these
chickens are sufficient for obtaining that precious coal chicken.
Let's use some handy dandy Punnett squares to take a look at the path from
feather to coal chickens. Because both chickens have homozygous dominant genes
in D, F, S, and W, you can ignore those in your Punnett square and focus on
BbCC and BBCc. Here is what your square will look like:
| . | BC | bC |
|---|---|---|
| BC | BBCC | BbCC |
| Bc | BBCc | BbCc |
As you can see, there is a 1 in 4 chance that these chickens will produce a
child that is heterozygous in both genes, which is the ideal chicken for
getting to the bbcc coal. However, you are not there yet. To move onward you
will need 2 chickens with BbCc DNA that have fully grown into adults. Once you
have them, your Punnett square will be:
| . | BC | bC | Bc | bc |
|---|---|---|---|---|
| BC | BBCC | BbCC | BBCc | BbCc |
| Bc | BBCc | BbCc | BBcc | Bbcc |
| bC | BbCC | bbCC | BbCc | bbCc |
| bc | BbCc | bbCc | Bbcc | bbcc |
Suddenly your odds are not looking so great... You are down to 1 in 16 odds of
getting the chicken you want, which although not impossible, will likely be
painfully slow without amazing luck. Fortunately, there are ways to improve your
odds and speed this up. Notice that in the bc column and row, there are four
chickens with 3 recessive alleles each, 2 Bbcc and 2 bbCc. As mentioned
above, homozygous genes are guaranteed to pass along a specific type of
allele, which doubles your odds of getting a coal chicken. Let's say that within
your first few attempts, you get a Bbcc chicken. If you shove it full of seeds
and accelerate its growth, you can swap it with one of the BbCc chickens. By
that alone, your Punnett square is halved in size:
| . | BC | bC | Bc | bc |
|---|---|---|---|---|
| Bc | BBCc | BbCc | BBcc | Bbcc |
| bc | BbCc | bbCc | Bbcc | bbcc |
This brings you from 1 in 16 odds to 1 in 8 odds. This can be halved again to 1 in 4 odds if you get another one of the chickens with 3 recessive alleles:
| . | bC | bc |
|---|---|---|
| Bc | BbCc | Bbcc |
| bc | bbCc | bbcc |
Now, getting one or multiple coal chickens can happen at a much more tolerable pace.
It is worth mentioning that while Punnett squares can be somewhat confusing and
cumbersome to use, there is a faster way of calculating your odds. Because
homozygous genes are certain to pass on one type of allele and any
heterozygous genes have a 50% chance of passing a desired allele, to get a
chicken with a homozygous DNA sequence simply count the number of
heterozygous genes in each parent's DNA and raise 2 to that power. To reuse
the previous example with the 2 BbCc chickens, there are 4 heterozygous
genes between the two chickens, meaning the odds of getting bbcc would be
1/2^4 = 1/(2*2*2*2) = 1/16. As another example, you could try to get a
Netherite chicken from two feather chickens with DNA BbCcDdFfSsWw, however you
would be looking at 1/2^12 odds, or 1 in 4,096, so you're far better off
working down the tiers to give yourself better odds throughout the whole
process.
There is a command available to calculate the odds that a parent
will produce your desired child:
/gce calcchance <parent DNA> <parent DNA> <child DNA>
Congratulations! You now have all the knowledge you need to start breeding all types of chickens! There's still one more step before you can start creating resources, though, and that is using the Excitation Chamber to collect resources.