To produce designer pythons, 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.
Dominant
A python
morph is said to be dominant if there is no visual differences in skin
colour or pattern between their homozygous and heterozygous morphs.
Examples 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 use for Dominant genes and two
letters are given for each parent. In the following examples a Normal
morph is described as NN and a Spider morph NS.
Normal (NN) x Normal (NN)
Possible Permutations for each Egg:
100% Normal
Normal (NN) x Spider (NS)
Possible Permutations for each Egg:
50% Normal
50% Spider
Normal (NN) x Spider (SS)
Possible Permutations for each Egg:
100% Spider
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 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).
Normal (NN) x Cinnamon (NC)
Possible Permutations for each Egg:
50% Normal
50% Cinnamon (Heterozygous)
Cinnamon (NC) x Cinnamon (NC)
Possible Permutations for each Egg:
25% Normal
50% Cinnamon (Heterozygous)
25% Cinnamon (Homozygous) aka Super Cinnamon
Cinnamon (NC) x Super Cinnamon (CC)
Possible Permutations for each Egg:
50% Cinnamon (Heterozygous)
50% Cinnamon (Homozygous) aka Super Cinnamon
Super Cinnamon (CC) x Super Cinnamon (CC)
Possible Permutations for each Egg:
100% Cinnamon (Homozygous) aka Super Cinnamon
Normal (NN) x Super Cinnamon (CC)
Possible Permutations for each Egg:
100% Cinnamon (Heterozygous)
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 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.
Amelanistic (aa) x Amelanistic (aa)
Possible Permutations for each Egg:
100% Amelanistic (Homozygous)
Normal (NN) x Amelanistic (aa)
Possible Permutations for each Egg:
100% Normal heterozygous for Amelanistic
Amelanistic (aa) x Normal Heterozygous (HET) for
Amelanistic (Na)
Possible Permutations for each Egg:
50% Normal HET Amelanistic
50% Amelanistic (Homozygous)
Normal (NN) x Normal Heterozygous (HET) for
Amelanistic (Na)
Possible Permutations for each Egg:
50% Normal
50% Normal HET for Amelanistic
As all hatchlings visually appear to be Normal looking,
then each hatchling is known as a Normal 50% possible HET for Amelanistic.
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)
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.
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!
Double HETs – Simple Recessive
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).
Amelanistic (aa) x Piebald (pp)
Possible Permutations for each Egg:
100% Double HET (or Snow) for Amelanistic and Piebald
As these are simple recessive genotypes all the
hatchlings will appear Normal looking.
Double HET Amel’ and Piebald (ap) x Double HET Amel’
and Piebald (ap)
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.
|
|
N |
a |
p |
ap |
|
N |
NN |
Na |
Np |
Nap |
|
a |
Na |
aa |
ap |
aap |
|
p |
Np |
ap |
pp |
ppa |
|
ap |
Nap |
aap |
ppa |
aapp |
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 Piebald
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)
As we did for the single HETs, we can simplify and
describe these as hatchlings as follows:
Normal 50% possible Snow for Amelanistic and Piebald
Amelanistic 66% possible HET for Piebald
Piebald 66% possible HET for Amelanistic
Amelanistic Piebald (Albino Piebald)
Double HETs – Co-Dominant/Dominant
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).
Pastel (NP) x Cinnamon (NC)
Possible Permutations for each Egg:
25% Normal
25% Cinnamon
25% Pastel
25% Cinnamon / Pastel aka Pewter
The Pewter combines the different colours and patterns
from the three genotypes (N, C, P) to produce a completely different
looking snake.
Double HET Cinnamon and Pastel (CP) x Double HET
Spider and Pastel (SP)
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).
|
|
N |
C |
P |
CP |
|
N |
NN |
NC |
NP |
NCP |
|
S |
NS |
CS |
SP |
SCP |
|
P |
NP |
CP |
PP |
CPP |
|
SP |
NSP |
SCP |
SPP |
SCPP |
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
Wow! That is a possible twelve different looking
snakes, including triple HETs – Cinnamon Spider Pastel and CinnaBee Super
Pastel
Double HETs – Combining Dominant and Simple
Recessive
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).
Cinnamon (NC) x Amelanistic (aa)
Possible Permutations for each Egg:
50% Normal HET Amelanistic
50% Cinnamon HET Amelanistic
Therefore we will have Normal and Cinnamon looking
snakes, all of which will carry the Amelanistic gene.
Cinnamon HET Amelanistic (Ca) x Cinnamon HET
Amelanistic (Ca)
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.
|
|
N |
C |
a |
Ca |
|
N |
NN |
NC |
Na |
NCa |
|
C |
NC |
CC |
Ca |
CCa |
|
a |
Na |
Ca |
aa |
Caa |
|
Ca |
NCa |
CCa |
Caa |
CCaa |
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
As before, we can simplify and describe these as
hatchlings as follows:
Normal 66% possible HET for Amelanistic
Cinnamon 66% possible HET for Amelanistic
Super Cinnamon 66% possible HET for Amelanistic
Amelanistic
Amelanistic Cinnamon
Amelanistic Super Cinnamon
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
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:
|
|
Ca |
Ca |
|
a |
Caa |
Caa |
|
a |
Caa |
Caa |
Possible Permutations for each Egg:
100% Amelanistic Cinnamon
NOTE: All amelanistic cinnamons are produced, this is
because both parents are homozygous for Amelanistic and one parent is
homozygous for Cinnamon.
