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Genetics Explained

Normal (NN) x Normal (NN)

 

Dominant

A morph is said to be dominant if there is no visual differences in skin colour or pattern between their homozygous and heterozygous morphs.  Examples of dominant Royal Python morphs are the Normal, Spider and Pinstripe.

We use punnet squares to calculate the possible permutations of a pairing and the resulting clutch.

To use the punnet square we first need to assign letters to describe the genotypes of the parents.  Typically capital letters are used for Dominant genes and two letters are given for each parent.  In the examples a Normal morph is described as NN and a Spider morph NS.

To produce designer morphs, we need to understand a little about genetics.  The reason is simple – to predict the genetic permutations of each egg produced from the combining of two parents with different morphs.

I will start with dominant genetics; continue onto co-dominant, then simple recessive and the combination of all three.

I have used Royal Python Morphs in the examples.

 

Possible Permutations for each Egg:

100% Normal

N
N
N
NN
NN
N
NN
NN

Normal (NN) x Normal (NN)

 

Possible Permutations for each Egg:

50% Normal

50% Spider

N
S
N
NN
NS
N
NN
NS

Normal (NN) x Cinnamon (NC)

 

Co-Dominant

There is a second dominant group - the so-called co-dominant.  The difference with this group to the dominant group is that there is a significant visual difference between their homozygous and heterozygous states.  Examples of dominant Royal Python morphs are Pastel, Cinnamon, Mojave and Lesser Platinum.

Homozygous versions of the co-dominants tend to be called ‘Super versions’ i.e. a homozygous Cinnamon is commonly known as a Super Cinnamon.  The Cinnamon is a brown, patterned python and the Super Cinnamon is a brown python with no pattern, hence visually very different.

We will again use punnet squares to calculate the possible permutations of a pairing and the resulting clutch.

In the following examples a Cinnamon Heterozygous is described as NC (one normal genotype and one cinnamon genotype).

Possible Permutations for each Egg:

50% Normal

50% Cinnamon (Heterozygous)

N
C
N
NN
NC
N
NN
NC

Cinnamon (NC) x Cinnamon (NC)

 

Possible Permutations for each Egg:

25% Normal

50% Cinnamon (Heterozygous)

25% Cinnamon (Homozygous) aka Super Cinnamon

N
C
N
NN
NC
C
NC
CC

Cinnamon (NC) x Super Cinnamon (CC)

 

Possible Permutations for each Egg:

50% Cinnamon (Heterozygous)

50% Cinnamon (Homozygous) aka Super Cinnamon

C
C
N
NC
NC
C
CC
CC

Super Cinnamon (CC) x Super Cinnamon (CC)

 

Possible Permutations for each Egg:

100% Cinnamon (Homozygous) aka Super Cinnamon

C
C
C
CC
CC
C
CC
CC

Normal (NN) x Super Cinnamon (CC)

 

Possible Permutations for each Egg:

100% Cinnamon (Heterozygous)

C
C
N
NC
NC
N
NC
NC

Amelanistic (aa) x Amelanistic (aa)

 

Simple Recessive

The final group is the Recessive or Simple Recessive.  Like the co-dominant group the heterozygous and homozygous are visually different.  The heterozygous takes on the appearance of the dominant heterozygous genotype not the recessive genotype.  Examples of dominant Royal Python morphs are Amelanistic (Albino), Piebald and Ghost.

The appearance of a homozygous Amelanistic python is a yellow and white python, but its heterozygous version is a Normal looking python.

We will again use punnet squares to calculate the possible permutations of a pairing and the resulting clutch.

Typically recessive genotypes are described using lower case letters.  In the following examples an Amelanistic Heterozygous is described as Na (one normal genotype and one amelanistic genotype) and an Amelanistic Homozygous is described as aa.

Possible Permutations for each Egg:

100% Amelanistic (Homozygous)

a
a
a
aa
aa
a
aa
aa

Normal (NN) x Amelanistic (aa)

 

Possible Permutations for each Egg:

100% Normal heterozygous for Amelanistic

a
a
N
Na
Na
N
Na
Na

Amelanistic (aa) x Normal Heterozygous (HET) for Amelanistic (Na)

 

Possible Permutations for each Egg:

50% Normal HET Amelanistic

50% Amelanistic (Homozygous) 

a
a
N
Na
Na
a
aa
aa

Normal (NN) x Normal Heterozygous (HET) for Amelanistic (Na)

 

 

Possible Permutations for each Egg:

50% Normal

50% Normal HET for Amelanistic

N
a
N
NN
Na
N
NN
Na

Normal HET for Amelanistic (Na) x Normal HET for Amelanistic (Na)

 

Possible Permutations for each Egg:

25% Normal

50% Normal HET for Amelanistic

25% Amelanistic (Homozygous)

N
a
N
NN
Na
a
Na
aa

Designer Morphs

This is where things get really exciting.  Firstly let’s explain the term ‘Designer Morphs’.  Designer Morphs are the combination of two different morphs.  In theory this can occur in nature, but is highly unlikely.  If we consider an Albino Piebald (which has been artificially produced by breeders) is there likely to be one living on the African plains?  Firstly Albino and Piebald Royal Pythons do occur in nature albeit very rarely and when hatchlings do appear their bright colours make them standout against the background.  Therefore the chances of predation of hatchling Albinos and Piebalds are much higher than for their Normal looking camouflaged siblings.  So it is unlikely for Albino and Piebald hatchlings to reach adulthood.  But lets imagine they did survive, what are the chances of these two different looking snakes finding each other in the large continent of Africa?  Worse still, as we will see later, that only by placing two of their offspring back together do we have a 1 in 16 chance of producing the Albino Piebald.  Therefore it is very very highly unlikely that an Albino Piebald is naturally occurring in Africa – I probably have more chance winning the lottery!

Amelanistic (aa) x Piebald (pp)

 

Double HETs is a term used to described a snake which heterozygous for two different morphs.  For simple recessive a Double HET is also known as Snow.  Using our example of combining an Albino (aa) to a Piebald (pp).

Possible Permutations for each Egg:

100% Double HET for Amelanistic and Piebald

a
a
p
pa
pa
p
pa
pa

Double HET Amel’ and Piebald (ap) x Double HET Amel’ and Piebald (ap)

 

 

 

Possible Permutations for each Egg:

6.25% (1 in 16) Normal

12.5% (2 in 16) Normal HET for Amelanistic

12.5% (2 in 16) Normal HET for Piebald

25.0% (4 in 20) Normal double HET for Amel’ and Pie’d

6.25% (1 in 16) Amelanistic

12.5% (2 in 16) Amelanistic HET for Piebald

6.25% (1 in 16) Piebald

12.5% (2 in 16) Piebald HET for Amelanistic

6.25% (1 in 16) Amelanistic Piebald (Albino Piebald)

N
a
p
ap
N
NN
Na
Np
Nap
a
Na
aa
ap
aap
p
Np
ap
pp
app
ap
Nap
aap
app
aapp

When combining simple recessive double HETs we need to remember there are three genotypes; in our example these are Amelanistic (a), Piebald (p) and the dominant genotype Normal (N).  These three genotypes provide four different combinations NN, Na, Np, NaNp which in the following example I will simplify to N, a, p, ap.

 

 

As these are simple recessive genotypes all the hatchlings will appear Normal looking.

 

As we did for the single HETs, we can simplify and describe these as hatchlings as follows:

Double HETs – Simple Recessive

Pastel (NP) x Cinnamon (NC)

 

 

Similar to the Simple Recessive the term Double HET for Co-dominants and Dominants is used to described a snake which is heterozygous for two different morphs.  The difference with a Co-dominant/dominant double het is that it is visually different than it parents or the Normal type.  In the example below we combine a Pastel (NP) to a Cinnamon (NC).

Possible Permutations for each Egg:

25% Normal

25% Cinnamon

25% Pastel

25% Cinnamon / Pastel aka Pewter

 

N
C
N
NN
NC
P
NP
CP

Double HET Cinnamon and Pastel (CP) x Double HET Spider and Pastel (SP)

 

 

 

Possible Permutations for each Egg:

6.25% (1 in 16) Normal

6.25% (1 in 16) Cinnamon

6.25% (1 in 16) Spider

12.5% (2 in 16) Pastel

12.5% (2 in 16) Cinnamon Spider aka CinnaBee

12.5% (2 in 16) Spider Pastel aka BumbleBee

6.25% (1 in 16) Cinnamon Pastel aka Pewter

6.25% (1 in 16) Super Pastel

6.25% (1 in 16) Cinnamon Super Pastel

6.25% (1 in 16) Spider Super Pastel

12.5% (2 in 16) Cinnamon Spider Pastel

6.25% (1 in 16) CinnaBee Super Pastel

N
C
P
CP
N
NN
NC
NP
NCP
S
NS
SC
SP
SCP
P
NP
CP
PP
CPP
SP
NSP
SCP
SPP
SCPP

When combining co-dominant/dominant double HETs we need to remember there are three genotypes; the two morphs and the Normal.  These three genotypes then provide four different combinations.  In this example we are combining Pewter (Cinnamon/Pastel, CP) and BumbleBee (Spider/Pastel, SP).

 

 

The Pewter combines the different colours and patterns from the three genotypes (N, C, P) to produce a completely different looking snake.

 

Wow!  That is a possible twelve different looking snakes, including triple HETs – Cinnamon Spider Pastel and CinnaBee Super Pastel

Double HETs – Co-Dominant/Dominant

Cinnamon (NC) x Amelanistic (aa)

 

 

When producing double hets using dominant and recessive genotypes, the resulting hatchlings will take the appearance of the dominant gene.  The following example combines a Cinnamon (NC) with an Amelanistic (aa).

Possible Permutations for each Egg:

50% Normal HET Amelanistic

50% Cinnamon HET Amelanistic

 

N
C
a
Na
Ca
a
Na
Ca

Cinnamon HET Amelanistic (Ca) x Cinnamon HET Amelanistic (Ca)

 

 

 

Possible Permutations for each Egg:

6.25% (1 in 16) Normal

12.5% (2 in 16) Normal HET Amelanistic

6.25% (1 in 16) Amelanistic

12.5% (2 in 16) Cinnamon

25.0% (4 in16) Cinnamon HET Amelanistic

12.5% (2 in 16) Amelanistic Cinnamon

6.25% (1 in 16) Super Cinnamon

12.5% (2 in 16) Super Cinnamon HET Amelanistic

6.25% (1 in 16) Amelanistic Super Cinnamon

N
C
a
Ca
N
NN
NC
Na
NCa
C
NC
CC
Ca
CCa
a
Na
Ca
aa
Caa
Ca
NCa
CCa
Caa
CCaa

When combining these double HETs we need to remember there are three genotypes; in our example these are Amelanistic (a), Cinnamon (C) and Normal (N).  These three genotypes provide four different combinations NN, Na, NC, NCNa which in the following example I will simplify to N, a, C, Ca.

 

 

Therefore we will have Normal and Cinnamon looking snakes, all of which will carry the Amelanistic gene.

 

 

As before, we can simplify and describe these as hatchlings as follows:

Double HETs – Combining Dominant and Simple Recessive

Amelanistic Cinnamon (Caa) x Amelanistic (aa)

 

 

If we now take the Amelanistic Cinnamon (Caa) and put it back with the Amelanistic, we get:

Possible Permutations for each Egg:

50% Amelanistic

50% Amelanistic Cinnamon

 

a
Ca
a
aa
Caa
Ca
Caa
CCaa

NOTE:  No simple recessive HETs produced, this is because both parents are homozygous for Amelanistic.

 

 

Amelanistic Super Cinnamon (CCaa) x Amelanistic (aa)

 

 

If we now take the Amelanistic Super Cinnamon (CCaa) and put it back with the Amelanistic (aa), we get:

Possible Permutations for each Egg:

100% Amelanistic Cinnamon

 

Ca
Ca
a
Caa
Caa
a
Caa
Caa

NOTE:  All amelanistic cinnamons are produced, this is because both parents are homozygous for Amelanistic and one parent is homozygous for Cinnamon.

 

 

As three quarters of the hatchlings visually appear to be Normal looking and two thirds of these are Hets, then each hatchling is known as a Normal 66% possible HET for Amelanistic.

As all hatchlings visually appear to be Normal looking, then each hatchling is known as a Normal 50%