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Madders

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Hi, ok if i have a crossbred python ( Ie spotted X Darwin for example) andIi wanted to breed back to a Darwin (hypothetically) how many generations would have to be bred before the animal was again considered a Darwin or is it always referred to as a percentage?
 
i have been told that even through breeding hybrids to normals heaps it cannot be considered the one species it will stay a percentage
 
If you want to explain it in a fun way, look up Zeno Paradox of Achillies and the Tortoise but instead of a race, just think of the genes getting "phased out" as such.
 
If you want to look at it in terms of percentages it's pretty easy. You just halve the difference for every generation. So the first 10 generations would be:
style="width: 141px"
|-
| style="height: 20px; width: 77px" | Generation
| style="width: 64px; text-align: center" | %
|-
| style="height: 20px; text-align: center" | 1
| align="right" | 50.00%
|-
| style="height: 20px; text-align: center" | 2
| align="right" | 75.00%
|-
| style="height: 20px; text-align: center" | 3
| align="right" | 87.50%
|-
| style="height: 20px; text-align: center" | 4
| align="right" | 93.75%
|-
| style="height: 20px; text-align: center" | 5
| align="right" | 96.88%
|-
| style="height: 20px; text-align: center" | 6
| align="right" | 98.44%
|-
| style="height: 20px; text-align: center" | 7
| align="right" | 99.22%
|-
| style="height: 20px; text-align: center" | 8
| align="right" | 99.61%
|-
| style="height: 20px; text-align: center" | 9
| align="right" | 99.80%
|-
| style="height: 20px; text-align: center" | 10
| align="right" | 99.90%
|-

After 7th generation you're up over 99% so I'd consider that to be close enough to be called pure again. Plenty of people would disagree with that assessment though.
 
Even if you went to 10th generation if the crossed species had a dominant gene trait that trait could appear again at any time down the line therefore strictly speaking it can never truely be the original species again. It is also a very slippery slope as I understand the 'Jag' arguement that it could also create a gene defect which could potentially blemish future generations ergo the same as my above logic.

We see it in humans too although it is more complicated but numerous generations of brown eyed couples can produce a blue eyed child etc. White couples in America have produced black babies not knowing there was negro genes four or more generations earlier.
 
Pure is regarded as 100%. Hence 99.99% is still not pure. Once you've crossed them the progeny will never be pure no matter how many generations you try to breed them so.
 
We see it in humans too although it is more complicated but numerous generations of brown eyed couples can produce a blue eyed child etc. White couples in America have produced black babies not knowing there was negro genes four or more generations earlier.

The blue eyes I get because blue is recessive but if a white couple had a black baby I'd be looking at the mail man before their genes. Have you got any links to this? I'd be interested to read about it. My understanding was that, by definition, dominant genes dominate recessive genes so your example should be impossible...
 
I might have mucked up the recessive/dominant thing as I'm an English teacher not a scientist. As for the other example it is something you can look up. Negro genetics unlike australian aboriginal genetics can create a throw back, that is a couple of generations later you can have a coloured baby to white parents.

Either way the basic theory behind what I was saying stands even if I mixed the terms around. You have introduced new gene traits and depending on what they are they can present themselves down the track which an originally pure animal won't, therefore the animal cannot be strictly speaking 'pure' again.
 
There is a possibility that you could breed a pure Darwin after the 1st generation. The odds of it occurring are very remote. The problem though is proving that it is a pure bred, you would have to get it genetically mapped. Each generation that you breed with pure stock increases the chances that a pure animal will be dropped. The cost and time of doing the genetic work and breeding the snakes would be ridiculous. It would be quicker and cheaper to just buy a Darwin carpet.
 
It's all very interesting, esspecially in that its possible to drop a pure in the first gen, but it is just hypothetical I've a coastal and a Darwin that are about two and three years off being ready to mate anyway and they are not getting crossed ever :)
 
I think the whole thing gets even more complicated in nature when you have intergrades occuring where species boundaries overlap. Your example was pretty extreme but it bends my head when thinking about carpet pythons as there are so many varieties.
 
A spottedxDarwin...what would that be? Anataresia Variegata? Morelia Spilota Maculosa?Antarelia Varielosa?????

We'll, I'm stumped!
 
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