W&Y    Identification Key by Karsten Grieshammer (2012)

Karsten Grieshammer

Karsten Grieshammer studied biology and is well known for working successfully with leopardgeckos and other repile species for many years. His personal huge experience with this morph comes from the fact that he has been one of the first and best known breeders for W&Y's in Germany and central Europe. He's co-author of several books including "Leopardgeckos" by Grieshammer & Köhler (2006).

“As I was asked quite a few times what makes a W&Y, I thought it would make sense to make my thoughts available here (especially as I just don`t have the time to answer e-mails and PM all the time). This information is without pictures, as better pictures as I could ever take are easily available. As english is not my first language, I hope everything is easy to understand.

Definition of the trait?

W&Y (as they were named by the originator) is the abbreviation for “White and Yellow”. W&Y is a dominant morph, that influences the body colour and pattern. Most W&Ys already hatch pretty much hypomelanistic and stay “hypo-ish” throughout their lives. Most W&Ys (at a younger age) have a clearly visible line that goes from the nostril to the eye and a small spot above this line that is not pigmented just in front of the eye. Most W&Ys keep their white neckband very long (some throughout their lives). Most W&Y have the tendency to show their body bands throughout their lives. Most W&Ys have a small dorsal stripe. Many of the W&Ys develop white sides from head to the tail tip (legs might be affected as well). Many of the W&Y hatch with a horseshoe marking the backpart of the head. A lot of the W&Ys develop paradox markings, mostly when they are older than 1 year. Some of the W&Y with a carrottail have an unpigmented spot at the base of their tail.
All of these signs don`t have to show up or can be heavily influenced in combination morphs.
From my point of view, an outstanding animal of this morph is brightly colored and has clear white sides.


Sergey Prohorchik hatched the first W&Y in the mid-90s and line bred the morph for more than a decade. He is available online (http://www.sprept.com/). If you want to learn more about the history of this morph, check http://www.leopardgeckowiki.com the data that is published there is identical to the information I have (1-march-2012).

Connection to other morphs?

Some W&Ys show similarities to Enigmas. Although similar genes might be affected, there is no evidence, that these morphs are related.
Combination morphs of Bell & Tremper Albinos, Mack Snows and line bred morphs as SHTCT, striped etc can be produced as they are already available. There is no morph known it can`t be combined with at this point.


W&Y is a dominant morph. Every animal that is heterozygous or homozygous shows the trait, so the genotype and phenotype are identical. If you breed a heterozygous W&Y to a wildtype, you will statistically find a 50/50 ratio. You can`t see if an animal is homozygous- you can only be sure when both parents are proven to be homozygous or the animal ONLY produces W&Ys itself. If you breed two W&Ys you will get ¼ homozygous animals, 1/2 heterozygous animals , ¼ wildtype.

Neurological or other health issues?

W&Ys are vigor and fertile. None of my animals showed a behavior that is different from any other leopard gecko. I have heard from very few people, that some of their homozygous W&Ys had a slight vestibular disorder. I don`t know if this is true (or might for example just be a mix-up with enigmas) at that point. If it is true just don`t breed two W&Ys together to be safe. Once I hatch a W&Y with issues, I will make the information available here.

Market value?

W&Ys were available in eastern Europe for quite some time and for quite reasonable prices. Those prices went up the last few years, due to an increased interest and new combination morphs.
As W&Y is a dominant trait, it is easy to produce masses of them. Take one low grade W&Y male and pair it to a decent number of females and you will be able to offer hundreds of W&Ys the first year. This will cause the market prices to fall very quickly and you can already find W&Ys at whole sale lists (in Germany) for very cheap prices.

BUT: Although being a rather old morph, W&Ys are just at their beginning! Just after very few generations in the hands of some breeders there are really outstanding examples of the morph out there. If you plan your breeding projects wisely there will be a big demand for what you will have to offer. W&Ys are very prone to line breeding and outcrossing and the breeding results are much more consistent as they are with enimgas for example.

There is always a market for outstanding leopard geckos. If you plan to produce masses of low grade W&Ys, prepare yourself to have difficulties to find new homes for them. Period.

Is my animal a W&Y?

To be honest: I don`t know. There are quite a few animals out there that are being sold as W&Ys that do not show any signs of the trait. On the other hand some W&Ys loose the signs of their trait as they grow, others will develop the paradox markings as they get older- and other animals show a lot of signs of being W&Y but they lack any genetically connection to this morph. As I was asked to give advice in several cases and my words were used against some breeders, I will no longer “validate” animals. If you don`t trust a breeder: don`t get animals from him. If you hatch something and you are not sure what it is- don`t sell it as something you cannot guarantee. Do your homework and start breeding with animals that show the signs of the morph very clearly. This will help you a lot to get experience with the morph.

Combination morphs?

You can find some nice additional information (including several combination morphs) in this video that was created and uploaded by Matt Baronak/sasobek reptiles: http://www.youtube.com/watch?v=iHzGpnbzipw

One more thing?

Yes:I`ve bred some quite interesting combos but I only breed very limited numbers. So please don`t ask me if I have something available. If I will, I post them here or in german classifieds. There are many breeders with very nice and healthy animals!

Once again please please don`t ask me if your animal is a W&Y. I can`t tell you anyways- and the attempt to try it took me hours of answering so many e-mails the past few months and my words were used against other breeders. I will no longer answer these questions. Sorry for that and thanks for your understanding!

I hope this information is useful!

Best regards


Original source with pics: http://geckoforums.net/f125-morphs-genetics/85320.htm

copyright by Karsten Grieshammer 2012