A Lesson in Basic Genetics

Layman’s Crash Course in Ball Python Genetics

This explanation is not meant to be taken as a scientific study or anything like that. It is written from a layman's point of view in order to offer a basic understanding of how genetics work in Ball Python breeding and the various genetic terms as they are commonly used in the BP community. Hopefully the visuals created for this lesson will provide a solid foundation for future learning.



GLOSSARY OF TERMS

Allele – One member of a pair of genes at the same locus.

Co-Dominant – A visible mutation appears when a single gene at an allele is different than normal. A matched pair of this gene brings about a “super” form that looks different than the single.

DNA -- Part of the genetic code that makes up all living things.

Dominant – A visible mutation appears when a single allele at a locus is different than the normal. A matched pair of the mutated alleles will appear the same as the single.

Gene – A molecular unit of DNA responsible for the physical and inheritable characteristics of an animal.

Heterozygous (Het) – An unmatched pair of alleles at any given locus…this term is usually reserved for recessive traits that do not show up even though one gene is present.

Homozygous (Homo) – A matched pair of mutated alleles at any given locus.

Locus– The location of a gene/allele on the DNA strand.

Recessive – A matched pair of mutated alleles must be together at the same locus in order to bring about a visible change.




HOW DOES ALL THIS WORK?

Picture a pair of shoestrings. Hold them up side-by-side. Now picture them with little matched pairs of colored balls stuck to each of them:



https://ball-pythons.net/images/asun...graphics-2.jpg



Each strand represents one of the two DNA strands all animals have.

Each colored dot represents a single gene or allele.

Each pair of colored dots represents a pair of genes/alleles located at a specific locus.



Each pair of genes has a different “job” in determining the look of an animal. It takes many different pairs of genes, each doing a specific job, just to determine the overall pattern and colors of a snake.



When two animals mate and create young, each parent contributes one copy from their pairs of genes to create a whole new set of pairs in the offspring. For instance, the red dots…one red dot from the mom and one red dot from the dad. Always. One yellow dot from the mom, and one yellow dot from the dad.



https://ball-pythons.net/images/asun...graphics-3.jpg



Most of the time, enough of these genes match up in such a way as to create what we call a “normal” or “wild type” appearance. Even within this “normal” range, there are so many different genes at work, and in so many different combinations, that the appearance of the animals will always have some variance…especially in a species like the ball python. There are many different looks that are all considered “normal.” For the purposes of this study, which is meant to lead to an understanding of breeding for various ball python morphs, let’s say that animals are considered “normal” because their specific genetic makeup is not only common, but is also too complicated and unpredictable to reproduce any single trait (such as lots of spots or a lack of spots) with any degree of certainty. Any visible trait that can be consistently and predictably reproduced is called “genetic” and the animals with these specific genetic traits are referred to as “morphs”.



WHAT MAKES A MORPH?

Occasionally, a single gene (or gene pair) will mutate outside of the normal variant range. This will cause the animal to look different from its normal peers and they will be called “morphs.” Some examples of this are Albinos, Axanthics, Spiders, and Pastels.



Different types of gene mutations will behave or affect the animal differently.



Many morphs are Recessive, which means they must have a matched gene pair in order to make a visual difference in the animal. Albinos, Axanthics, and Piebalds (Pieds) are examples of Recessive morphs.



And many other morphs are Dominant or Co-dominant, which means you can see a different look with just a single gene being represented.



What’s the difference between Dominant and Co-dominant?

A Dominant gene will produce the same look in the animal whether it is a single gene or a matched pair. Spiders and Pinstripes are examples of this type of morph.



A Co-dominant gene will produce one look when a single mutated gene is present and an entirely different look if there is a matched pair of the mutation. Pastels and Mojaves are examples of this.



So what happens when I breed XXX to xxx?



Let’s start with Recessives.



https://ball-pythons.net/images/asun...graphics-4.jpg



Notice the genetic chain for our Albino Mom. At one specific locus, instead of the yellow dots that a normal might have, she has a pair of A’s. The Dad is normal, so he just has yellow dots. Each parent contributes one gene from that locus to their offspring, and as you can see, the offspring has one A and one yellow dot. Because the Albino trait is recessive, it won’t show through the yellow dot on the other side and the baby looks normal. But she IS carrying an albino gene. (She is Het Albino.) And she has a 50/50 chance of passing that gene on to her own offspring as well. (Each baby she produces will either get the A or the yellow dot from that locus.) If she is mated to another snake that also carries at least one albino gene, then there is a chance one of their babies will inherit an A on both sides of the “shoe string” and display the bright yellow and white traits of an albino ball python.



The following graphics show the potential offspring of a Het Albino with another Het Albino, and a Het Albino with an Albino mate.



https://ball-pythons.net/images/asun...graphics-5.jpg



https://ball-pythons.net/images/asun...graphics-6.jpg



What about all those %’s people talk about?



When dealing with Het x Normal and Het x Het breeding pairs, all the Normal-looking offspring have a chance of being Het, but you can’t tell by looking whether or not it has the mutated gene. In a Het x Normal pairing…each offspring has a 50% chance of carrying the gene, so it is called “50% Het”. In a Het x Het pairing, all normal babies have a 66% chance of carrying the recessive gene and that’s where the “66% Het” term comes from.



Once one of these Possible Het animals mates with another carrying the same gene and produces visible morph offspring, they are considered “Proven” and are no longer referred to as “possible” or by any percentages. (Except maybe 100%. ;-) )



People sometimes use the term “100% Het” to refer to an animal that is an offspring of a visible morph because it is 100% certain that one copy of the recessive gene was passed on.



A Look at Dominant and Co-Dominant



With the Dominant morphs, it only takes one copy of the mutated gene to create a visual affect. With no known difference for having two copies. (Except that with a true homozygous form of a dominant morph, all the offspring would be guaranteed to carry the trait.)



Note the “S” represents the mutated gene that gives us the Spider morph, while a normal would have a light blue dot.



https://ball-pythons.net/images/asun...graphics-7.jpg



And here, we have the potential offspring of a Spider x Spider pairing. I have used “???” in place of an image for the “Homozygous Spider” because, as of my understanding at this time, no one has offered proof of their existence. Speculation is that a homozygous form would look no different than a spider with a single mutated gene. Therefore, it would be impossible to determine if a spider were “super” until it had produced several clutches of entirely spider offspring. But there is also speculation that when that mutated gene is paired with a matching one, the results are fatal, and therefore, no “super spiders” have survived incubation.



https://ball-pythons.net/images/asun...graphics-8.jpg



And now we’ll take a look at Co-Dominant morphs.



There are many co-dominant morphs, but our example here will be using the “Yellow Belly” and “Ivory” morphs. While the differences from a Normal can be subtle, the Yellow Belly (YB) has distinct characteristics that can be consistently recognized and passed on to offspring. When the snake is carrying a single mutated gene on this particular locus, it is called Yellow Belly or Het Ivory. When both copies of the mutated gene are present, the animal is called an Ivory and has a completely different look from its Het form.



These next two graphics show what you can get when you mate a YB to a Normal and a YB to another YB. Here, the mutated gene is represented by a Y and the normal gene by a blue dot.



https://ball-pythons.net/images/asun...graphics-9.jpg



https://ball-pythons.net/images/asun...raphics-10.jpg



If you mate a Yellow Belly to an Ivory, all the babies will be either YB or Ivory. And two Ivories will give you all Ivories.



So how do you know if a morph is Recessive or Dominant or what?



It’s basically just a learning curve you have to get yourself over. Here are some lists of basic morphs and which category they fall into. It is far from exhaustive.



RECESSIVE:
Albino
Axanthic
Caramel Albino
Clown
Genetic Stripe
Ghost (Hypo)
Lavender Albino
Piebald (Pied)

DOMINANT:
Pinstripe
Spider

CO-DOMINANT:
Butter – Blue Eyed Leucistic
Cinny – Super Cinny
Enchi – Super Enchi
Fire Ball – Black Eyed Leucistic
Lesser – Blue Eyed Leucistic
Mojave – Blue Eyed Leucistic
Pastel – Super Pastel
Yellow Belly – Ivory



This has been a very basic and simple overview of Ball Python genetics. If one wants to dig deeper, one can begin to look into combo-morphs, where multiple gene pairings are being manipulated. There are also morphs out there being worked with whose genetics are not yet fully understood with “hidden genes” and other mysteries. There are sometimes combinations of morphs that seem to go against these basic rules, such as a Het Axanthic causing a visual difference when combined with a Pastel. There are issues of “compatibility” to be aware of, and different “lines” of morphs. Sometimes the same morph will have different names. There is much to learn and absorb and it should be seen as an exciting challenge to work on for the rest of your life!



LEARN MORE:

Markus Jayne's Genetics
Ralph Davis' Morph Matrix
NERD's Ball Python Morph Gallery
BP.net's Morph FAQs
NextWorldExotic's Hunter's Guide to Morphs
Punnett Square Calculator

____________________
Authored by JLC of Ball-Pythons.net

PS -- If anyone sees any glaring factual errors, please shoot me a PM and let me know and I will change them ASAP.


I will leave this thread open for any Q&A that folks might have to provide a continuing source for learning all in one place. :)

:bow: :rockon:

Wow..what a fantastic gift to the community :grouphug:

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Originally Posted by cueball

Wow..what a fantastic gift to the community :grouphug:

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I don't think it could be said any better. And to think I had to go research all of that on my own when I learned it. There should be many grateful people sending you praise Judy. Thanks for this wonderful cointribution.

Judy this is a wonderful thing you've done for the people of this community, and I dont know what BP.Net would do without you!

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Originally Posted by muddoc

I don't think it could be said any better. And to think I had to go research all of that on my own when I learned it. There should be many grateful people sending you praise Judy. Thanks for this wonderful cointribution.

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THIRDED!!!! Great, ez read.... GREAT WORK!!!!!! :grouphug: 's for Judy!!!!!

vBulletin Message

You must spread some Reputation around before giving it to JLC again.

Bah humbug!

a MUCH needed stickie!!!!!


Great Work Judy...

Awww thanks, guys! :oops: I just hope someone learns something from it!


JR...you can just go head and spread some around and then come back to this one. :P :P :P (I am SO kidding!!! :rofl: ) Knowing you great folks think it is worthwhile is all the kudos I need!

Judy, absolutely amazing - but coming from an absolutely amazing woman, who would expect less? :hug:

Judy what a great job! You made it look so simple. So much easier to understand and absorb than a punnets square. You are a blessing to this community! :)

Judy that is just beyond words hon! What a great thing to do for the community. There are a few threads here that I keep handy to pass along to every newcomer I meet (Daniel's shed thread, Christie's bad shed thread, BPNet caresheet, etc.). Yours will join that group because this is a must read as far as I'm concerned! I'd have given a kidney for this short of sticky when we got our first BP and contemplated breeding her one day!

http://i41.photobucket.com/albums/e2...reTheWoman.gif

Great job Judy http://i127.photobucket.com/albums/p...ons/Bravo2.gif

Very informative, thanks ;)))

Wonderful job Judy!

Wow...amazing!

WOW, that would have taken me a year or two to complete..........

Truly great job......

Thanks for taking the time to do that for us!

WOW Judy!

http://i34.photobucket.com/albums/d1...e/23_32_10.gif

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Originally Posted by cueball

Wow..what a fantastic gift to the community :grouphug:

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Quote:

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Originally Posted by muddoc

There should be many grateful people sending you praise Judy. Thanks for this wonderful cointribution.

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dittos all that!

:gj:

this page has answered many of my questions but i still dont know- whats a *het* and what's the difference between a *het* and a *normal*?

A het is a normal appearing snake that carries one copy of the gene needed to make a recessive morph.

So - a pied (which is recessive) needs two copies of the pied gene to be a visual pied. If a pied is paired with a normal, the resulting offspring all get ONE copy of the pied gene, so they only express themselves as a normal appearing baby, but are 100% het.

You breed 2 100% hets of the same gene to each other - in this case pied, each egg has a 25% chance of receiving a copy of the gene from both parents, resulting in a visible pied.

Buy from a reputable breeder when working with hets, since they appear normal.

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Originally Posted by rabernet

Buy from a reputable breeder when working with hets, since they appear normal.

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Or at least make sure the breeder has some form of documentation to prove the Het or Possible Het genes exist. Regardless of the method you have to make sure you are comfortable with the deal cause 3 years later when you breed the hets still no gaurantee exists that you will get the homo form. It may take a couple breedings before you finally get the homo form and when you are paying $700+ for a female Het pied that is a lot to swallow for some people when she looks like a normal. :weirdface Regardless of those facts Hets are fun to work with.

my question is, is lavender albino, abino, and caramel albino on the same allele?

Yeah, right now my small group is attempting to bust into the world of Ball Breeding, our big goal for now is to make a killer bee - axanthic, i know how to make killer bee, super pastel x Bumble bee, but then do i just mate the killer with the axanthic over and over till we get a mix?? or is there another path i need to follow to get to the killer axanthic???


So far we got:
08' spider
07' paster M
00' normal
soon to own 08' mojave

Hi,

I'm sure there will be better recipies posted but here's the cliff notes.

Since axanthic is recessive both parents would need to carry the gene and, since the killer is a super pastel they would also need to carry the pastel gene.

So to get the axanthic killer bee you would need to breed something like;

Bumblebee het axanthic x Pastel het axanthic

Does that help?


dr del

This heloped me sooo much !! yay

Great Lesson Judy.......Thanks

Hey Judy:

My question has to do with something I noticed in Barker and Barker on page 63. They show a photo of a BP with an 'S' in the pattern and note that some consider it a genetic marker. Is there anything to this?

Norm Grant:

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Originally Posted by Norm Grant

Hey Judy:

My question has to do with something I noticed in Barker and Barker on page 63. They show a photo of a BP with an 'S' in the pattern and note that some consider it a genetic marker. Is there anything to this?

Norm Grant:

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Most refer to that "S" as a "hook". A significant number of morphs have them, and therefore, they are considered by many ONE of the markers to signal a snake could be genetic. Hope this helps.:)

Added to favourite & gave 5-stars..

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Originally Posted by JLC

Layman’s Crash Course in Ball Python Genetics

What about all those %’s people talk about?



When dealing with Het x Normal and Het x Het breeding pairs, all the Normal-looking offspring have a chance of being Het, but you can’t tell by looking whether or not it has the gene. In a Het x Normal pairing…each offspring has a statistical 50% chance of carrying the gene, so it is called “50% Het”. In a Het x Het pairing, all normal babies have a 66% chance of carrying the recessive gene and that’s where the “66% Het” term comes from.



____________________
Authored by JLC of Ball-Pythons.net

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Great info. Thank you for posting it to help newbies like me.

So I was hoping to find my answers here in this section but I didn't. So this is what Im curious about related to this subject:

%50 x %50
%50 x %66
%50 x %100

%66 x %66,
%66 x %100

Are they possible hets with just percentage that have to be mathematically figured out?

And I would logically assume that a visual morph x with any % het would make %100 het, if not, visual morph.

Please enlighten me. Thank you. :)

Quote:

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Originally Posted by t-Roy

Great info. Thank you for posting it to help newbies like me.

So I was hoping to find my answers here in this section but I didn't. So this is what Im curious about related to this subject:

%50 x %50
%50 x %66
%50 x %100

%66 x %66,
%66 x %100

Are they possible hets with just percentage that have to be mathematically figured out?


And I would logically assume that a visual morph x with any % het would make %100 het, if not, visual morph.

Please enlighten me. Thank you. :)

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All of the pairings that you mentioned apart from the 100% het involved breedings would have to be considered normal offspring.
You can't breed 2 50% together and produce all normal looking babies and still consider them possible hets in regards to the clutch.
You will need further breeding trials to establish if any of the parents are in fact heterozygous animals.
50% simply means that one parent was het.
66% means that both parents were het but the baby is normal in appearance.
Since if you had 4 eggs, you have a 1 in 4 chance of producing a homozygous animal. Leaving you with 3 eggs, all normal appearing and a 2 out of 3 chance for the gene to have passed on. (66%)
Do yourself a favour and get yourself a 100% het for the trait if you want to start proving out possible hets.
Better yet, if all of the possible hets are for the same morph then buy the visual homozygous animal and have a 50% chance at producing visual morphs if the parent turns out to be a het.
-Steven

CO-DOMINANT:
Butter – Blue Eyed Leucistic
Cinny – Super Cinny

What do the second names mean? like I know their morphs and all but is it just a different name or something? or what?

Quote:

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Originally Posted by TylerxToxic

CO-DOMINANT:
Butter – Blue Eyed Leucistic
Cinny – Super Cinny

What do the second names mean? like I know their morphs and all but is it just a different name or something? or what?

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Tyler this is more of an information thread. Specific questions you might have are likely going to get more responses if you start your own thread asking about what you need to know. :)

Thank you so much! This thread has helped me tons, as a total newbie to genetics (and one who is looking to breed :D)!

That really helped a ton with knowing which morphs are recessive, dom and codom. Thanks a bunch!!!! :)

that was very informative and it really helped me understand the lingo on these forums alot better. im new to the herp world and im growing very strongly attached. being more "in the know" is just making my desire for this hobby that much more intense XD
great job, i learned alot :bow:

awesome, amazing.....so let me ask you this mojave x mojave = leucistic

This is Great!! is there a printable or pdf version of it?

Thanks
Travis

You can copy and paste it into another document . . . I did when Judy posted this 2 years ago. Then you can print it out if you want to.

It's still the best piece on explaining genetics. I use it all the time to help others understand. Thanks again Judy.

Wow thank you so much! It will be a while before I get into breeding (if I ever do) but the info is still so valuable! Plus now I have a better idea of how people are getting what they are!

wow that is what I have been looking for a great break down of the genetics of ball pythons thanks for writing this.

lance

great post:) that info is priceless and another example of why bp.net is what it is:)!!!

Who needs biology! lol
I had a fantabulous time reading it. Loved the visuals ::gj:

i think you just saved me a few years of college by teaching me the one thing i wanted to learn in one shot lol now i can concentrate on buisiness courses lol thank you for saving me some $$ massive kudos

Hi I am kind of new to this and I was wondering what het means as in het albino and what morph would I get breeding a male norm and a honeybee female

Thanks for this information, very helpful and informative. i just have a question i have been wondering about. when you breed ball pythons, do the morphs have any deficiencies as far as the immune system, etc or are they the same as the normal breeds?

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Originally Posted by bigray2110

Thanks for this information, very helpful and informative. i just have a question i have been wondering about. when you breed ball pythons, do the morphs have any deficiencies as far as the immune system, etc or are they the same as the normal breeds?

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I have the same question. Is the breeding for morphological changes producing mutations that negatively impact the overall robustness of the species? Or is there enough diversity within the existing gene pool that dilution will not be a problem?

We see these types of problems in dogs. Why not in snakes?

Hi,

I am soooo not the person to answer this but I'll have a crack at it. :oops:

The first thing to clear up is that we are not breeding for mutations at all.

All the base morphs we know of originated in the wild. We may combine them to make designer morphs but that's all we can do. I don't think I have heard of anyone having a morph spontaneously created in a captive population, proving out WC snakes yes, but not generating something new.

Likewise all the morphs that do have some kind of problems ( spiders wobble, caramels can kink, cinamons and black pastels can have duckbills, BEL's can have bug eyes etc. ) are the way they are without man interfering.

If people spend enough generations breeding for traits then it is possible that they will create a situation similar to what we see in dogs but we are not even at the beginning of that process yet.

There also seems to be a difference between mammalian genetics and reptilian in terms of robustness to mutation and copy errors but I , honestly, do not know enough about this to even have a guess at reasons and results.

So, to answer your question as best I can, the only problems with mutations are the ones nature dealt out and aside form the known problems the animals themselves seem to be just as robust and healthy as the wild type.

But, as noted in the dog question, we are only just at the very, very beginning of this process and most, if not all, the morphs haven't been around long enough to truly know how their lifespan compares to the wild type etc.


dr del