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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

信息

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:

.BCbC
BCBBCCBbCC
BcBBCcBbCc

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:

.BCbCBcbc
BCBBCCBbCCBBCcBbCc
BcBBCcBbCcBBccBbcc
bCBbCCbbCCBbCcbbCc
bcBbCcbbCcBbccbbcc

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:

.BCbCBcbc
BcBBCcBbCcBBccBbcc
bcBbCcbbCcBbccbbcc

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:

.bCbc
BcBbCcBbcc
bcbbCcbbcc

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.