On Polygenic Outcrosses

Updated: May 31, 2019

Repost: Originally posted on Facebook November 29, 2017


Line-breeding for a specific trait or group of traits is not an uncommon practice in captive wildlife management and it’s certainly not limited to the reptile hobby. In fact line-breeding is very much a well known practice in many settings especially livestock, and, of course, in our beloved “mans best friend” the domestic dog. Dog breeds are in fact line bred traits.


In the blue tongue community we too have “breeds” although nobody in the BTS community calls them that and I don’t suggest anyone start...lol. Mostly they are called line-bred or polygentic traits aka visual traits.


There are several traits that have become quite popular and are continuing to grow in both demand and availability. Most of these traits occur in the Northern Blue Tongue Skink (Tiliqua scincoides intermedia).



Hypo/Sunset - Line-bred trait


The most common trait at this time that I have observed is called the “Sunset” which was first bred by Andrew Seike. It refers to animals with incredible tones of deep orange all over the body.


Any animal that is claimed to be a "sunset" MUST be traceable back to Andrew Seike lines or it is indeed a false claim. Period.

Now days there are many legitimate “sunset” blue tongues across the US and even now in Europe. In addition, there are animals known as "sunset outcrosses" meaning a sunset animal was bred to a non-sunset animal.


Most outcrosses have no visual expression of the trait. Although, sometimes they portray a diluted expression of the trait (occasionally a 1st generation outcross will have high expression). If a high expression outcrossed animal is bred back to a pure sunset animal there is a chance that some of the genetic material will line back up to produce offspring with a similar corresponding trait... but there is no guarantee. Therefore, buying outcrossed animals are a gamble. They are not a "sure thing" like a heterozygous animal might be.


Okay here is the issue:


Many smaller breeders, vendors, and even scammers have jumped on the "high end" bandwagon by labeling their animals as sunset outcrosses, sunset linage, etc. hoping to take advantage of a passionate unknowing customer who thinks they are buying something more than they are. So again, a 1st gen outcross may be worth a tad more for the concentrated genetics but not like an animal who was a heterozygous carrier of a simple recessive genetic trait (aka albino, axanthic etc). And again, being able to legitimately trace animals back to Andrew Seike for sunsets or whoever for whatever trait is the ONLY way to confirm said lineage.


Furthermore, high prices on outcrosses (especially 2nd gen +), from my perspective, is highway robbery. In reality unless you breed a 1st generation outcross back into that very trait on the very next generation you just have normal/classic offspring once again. Sure some genes for the special trait may be "concentrated" in the animal but no where near enough for high consistent expression warranting elevated pricing.


In fact, outcrossing line-bred traits is a massive step backwards from the line expressions.

I'm not denying that outcrossing is indeed healthy for the line. Absolutely, adding fresh genes into a line is a great way to keep them healthy. However, it takes a massive step backward from true line expression. That would be one of the reasons why diverse yet pure lines are so expensive because of the time and energy spent on raising up outcrosses to breed back into the line.



Classic Northern Blue Tongue Skink showing high orange expression

Think of is this way... if I were to breed a pure AKC Yellow Labrador Retriever to a pure AKC Standard Poodle (both are line-bred traits of the common dog) I would get offspring that would be considered outcrosses for both traits. Nobody would expect that breeding those puppies would create Yellow Labs or Standard Poodles or anything close. They would be an entirely different animal carrying partial traits from both parents.


It would take generations of breeding them back to either a poodle or a lab for someone to get animals resembling one or the other. In fact, as I understand it, the AKC requires animals to produce consistent traits for 10 (yes TEN) generations before they could be considered part of that line again.


Think about that next time you see a high price tag on a 2nd gen outcross and expect to get something fancy from breeding them.


No, the blue tongue skink community is not the AKC but still the idea applies.


So, to my fellow enthusiasts, buyers, sellers, breeders, and keepers trust but verify and don’t always take a labeled animal at face value.


A 2nd gen outcross is nothing more than a classic as far as I'm concerned.....


#bluetongueskink #morphs #linebred

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