# Random Genetics



## otb2 (Nov 30, 2006)

What would I get if I bred a Normal royal with either a spider or pastel?
I'm guessing normal het spider/pastel. Would I get any other combination?


----------



## alan1 (Nov 11, 2008)

otb2 said:


> What would I get if I bred a Normal royal with either a spider or pastel?
> I'm guessing normal het spider/pastel. Would I get any other combination?


no hets...

normal x spider = 50% normal, 50% spider... chance per egg
normal x pastel = 50% normal, 50% pastel... chance per egg

ALL dominant & co-doms "should" throw a 50/50 morph/normal clutch when bred to a normal...


----------



## bothrops (Jan 7, 2007)

alan1 said:


> no hets...
> 
> normal x spider = 50% normal, 50% spider... chance per egg
> normal x pastel = 50% normal, 50% pastel... chance per egg
> ...


 
just to clarify, they will indeed be hets it's just that with dominant and codominant genes the hets are visual for the trait. i.e the spiders with be heterozygous for spider/normal and the pastels will be heterozygous pastel/normal.


Other than that - all good: victory:


----------



## alan1 (Nov 11, 2008)

bothrops said:


> just to clarify, they will indeed be hets it's just that with dominant and codominant genes the hets are visual for the trait. i.e the spiders with be heterozygous for spider/normal and the pastels will be heterozygous pastel/normal.
> 
> 
> Other than that - all good: victory:


andy... you do a top job at "confusing the hell" outta people...

hets (to alot of people) are associated as "the hidden gene/morph within"...


----------



## Blackecho (Jun 30, 2008)

And people should be educated


----------



## bothrops (Jan 7, 2007)

alan1 said:


> andy... you do a top job at "confusing the hell" outta people...
> 
> hets (to alot of people) are associated as "the hidden gene/morph within"...


regardless of how many people _think_ thatis true, it is not. It is categorically, 100% *WRONG*. Therefore I will not sit back and allow the myth to be purpetuated.

Surely you can see that telling people that 'het' means hidden might lead to someone happily buying a completely normal snake as a 'het pastel' or a 'het mojave' due to some unscrupulous dealer/breeder.

I have said this many times before and I will continue to say it every time I see incorrect information given out on the forum.

Het means 'heterozygous' which means 'different genes'. not hidden, not morph within, but different. That is ALL it means and all it ever will mean despite how many people who have never had that explained to them believe different.

Just because 'a lot of people' understand things differently doesn't make them right.

Genetics is not the easiest of things to understand and therefore it is vitality important that when simplifying it so others can understand that we don't use half-truths or purpetuate our own misunderstandings.


I'm sorry if I come across as 'short' or 'pompous' or 'patronising' or anything else, but as you say 'many people' believe 'het means hidden' if I hadn't have posted this on this post, you would have just created yet another person who believes this incorrect piece of information as fact.



Regards

Andy


----------



## alan1 (Nov 11, 2008)

so, you are saying that ALL co-dom royals are "hets"?, because ALL of the "supers" are different from the single gene co-doms...


----------



## bothrops (Jan 7, 2007)

alan1 said:


> so, you are saying that ALL co-dom royals are "hets"?, because ALL of the "supers" are different from the single gene co-doms...


Yes. Exactly.

For any particular gene locus the snake will be one of three things

a) homozygous 'normal' - i.e. the pair of genes are the same and completely normal

b) heterozygous (or 'het) - meaning the pair of genes are different. 1 is normal and the other has mutated.

c) homozygous 'mutant' - both are the same but are both the mutant form.


Then, on top of this you then need to understand how the mutation interacts with the normal version of the gene.

If the mutation is recessive then

homozygous normal = looks (and is!) normal
heterozygous = looks normal but carries trait
homozygous mutant = visual for trait

if the mutation is co-dominant

homozygous normal = looks (and is!) normal
heterozygous = looks different from normal, exhibits trait (mojave/pastel etc)
homozygous mutant = looks different from both **** normal and het form

if the mutation is dominant

homozygous normal = looks (and is!) normal 
heterozygous = looks different from normal (exhibits trait)
homozygous mutant = looks exactly the same as the heterozygous form




You will notice that 'het = hidden' only works for recessive mutations, but that is an artifact and not because het actually _means_ hidden. 

You will also notice that a recessive mutation works in exactly the same way with normal as a normal gene works with a dominant mutation. Thats because they are exactly the same.

Albino is recessive to normal therefore normal is dominant to albino
Spider is dominant to normal therefore normal is recessive the spider.

In ALL cases, the heterozygous description refers ONLY to the fact that the two genes are different at that locus. It is the terms 'recessive', 'co-dom' and 'dominant' that defines how the snake LOOKS.


The terms we use are 'phenotype'; meaning what they LOOK like

i.e. the het albino is phenotypically normal

..and 'genotype' meaning what the animal is in terms of its genetics

i.e. the normal is genotypically heterozygous


Hope that helps clear it up, if not please ask for clarification on any or all points....: victory:


----------



## alan1 (Nov 11, 2008)

bothrops said:


> Yes. Exactly.
> 
> For any particular gene locus the snake will be one of three things
> 
> ...


f:censor:, my head hurts... *^ STICKY ^ *???


----------



## Blackecho (Jun 30, 2008)

Nice one Andy


----------



## MrMike (Jun 28, 2008)

bothrops said:


> Yes. Exactly.
> 
> For any particular gene locus the snake will be one of three things
> 
> ...


Perfectly put.


----------



## alan1 (Nov 11, 2008)

AGREED... have learnt something here... cheers andy...


----------



## repkid (Nov 30, 2007)

Good post there!

I personally think of "heterozygous" as meaning that animal only carries one gene for that morph. Then exactly as you have said you then need to work out what it looks like depending upon whether it is recessive, codom or dom.

Whereas "homozygous" means that animal carries two genes for that morph.

I think there should definately be a sticky on the differences and the REAL meanings of the two words so beginners to the subject of genetics will not get confused.


----------



## paulh (Sep 19, 2007)

repkid said:


> Good post there!
> 
> I personally think of "heterozygous" as meaning that animal only carries one gene for that morph. Then exactly as you have said you then need to work out what it looks like depending upon whether it is recessive, codom or dom.


You are better off thinking "different". First, because a gene pair contains two genes. We must not forget the normal gene when it is present in a gene pair. Second, because a gene pair that is heterozygous could contain a normal gene and a recessive mutant gene, a normal gene and a dominant mutant gene, a normal gene and a codominant mutant gene, or *two different mutant genes*. In royal pythons, a gene pair containing a mojave mutant gene and a lesser platinum mutant gene is heterozygous. In corn snakes, a gene pair containing a motley mutant gene and a stripe mutant gene is heterozygous.



repkid said:


> Whereas "homozygous" means that animal carries two genes for that morph.


A gene pair that contains two normal genes is also homozygous.



repkid said:


> I think there should definately be a sticky on the differences and the REAL meanings of the two words so beginners to the subject of genetics will not get confused.


It's already in one of the stickies. Genetics questions you were afraid to ask.


----------

