The nuts and bolts of leopard gecko genetics: terminology.
- Homozygous – visually displaying a given genetic trait.
- Heterozygous – carrying the gene for a given trait, but can only be passed on through reproduction.
- Recessive – the genetic trait stays “hidden”. Such specimens are heterozygous.
- Co-dominant – the trait is passed on visibly, following the same rules of inheritance as heterozygous and homozygous.
- Polygenetic – visually appearing marks, patterns or colors. Can be improved or reduced through generations of selective breeding.
- Line bred – a trait or traits that are continually being expressed to a higher degree by breeding related animals together.
Common Morphs and Trade Names
Tremper Albino – the first albino gene to be discovered in leopard geckos, purchased by and named after Ron Tremper. This trait is simple recessive.
Bell Albino – another albino trait that cropped up in Mark and Kim Bell’s collection. This trait is simple recessive.
Las Vegas Albino – the second albino strain appeared in the collection of a Las Vegas reptile store. This trait is simple recessive.
Albinos: It’s important, no, CRITICAL to note that these three albino genes cannot be combined. By breeding animals together of different strains, there will be no expression of albinism, and the genealogy will be compromised. This is by far the most taboo subject in the world of leopard geckos.
Murphy Patternless – a unique trait whereby the gecko matures with a solid yellow/brown body without pattern. Hatchlings will have a mottled/spotted pattern. The tail will be white, and usually have orange at its base. Still erroneously referred to as “leucistic” at times. This trait is simple recessive, and was discovered in 1991 by Pat Murphy.
Blizzard – another patternless mutation, only the babies hatch a solid steel-gray, and remain so all the way into adulthood. Sometimes a yellow tint garnished the scales, and some specimens can get very dark. Possibly the true leucistic morph in leopard geckos. This trait is simple recessive.
Mack Snow – anerythrism whereby yellow and orange are nearly unable to be expressed. Co-dominant, specimens in the heterozygous form will sometimes develop considerable amounts of yellow, but usually have bolder or more speckled markings than a normal gecko. The “super” form is black and white, and very unmistakable. Discovered by John and Amy Mack.
Giant –proven co-dominant by several breeders, this is a genetic mutation that affects the overall size of the gecko. Giants tend to be very variable, and can be the same size as a non-giant, normal sized gecko. Super giants, however, grow much longer than normal geckos and are fairly easy to pick out by one year of age. Some breeders believe there to be physical indicators such as elongated snouts, limbs and tail, but I’ve found that this may indeed be polygenic expressions within the gene. Some of my super giants are much more stout and stocky, while others are longer and more lanky. Further seasons of breeding will allow for more conclusive observation.
Jungle – one of the early mutations in leopard geckos, “jungle” refers to an aberrant patterning on the body and tail. Animals typically have a swirling pattern, or defined blocks of color outlined by black. Polygenetic in nature.
High Yellow – animals selectively bred for reduced spotting and larger areas of yellow ground coloration were termed “high yellow”. This is likely the first “morph” in leopard geckos, originating in the early-mid 1990’s.
Stripe – likely tied to the jungle trait, stripes are selectively bred to have a solid line of black down each side of the back and through the tail. Today there are several different designer striped variants, including the bold stripe, the red stripe, and lavender stripe.
Bold – animals displaying thick black markings that do not fade away with age are termed “bold”. Another polygenetic trait, and the base of other traits such as the bandit.
Bandit – the designer jungles, stripes and bolds all resulted in a very meticulously crafted gecko with distinct, sparse and bold head markings. A bandit should have a strip of thick black across its nose, in front of the eyes, giving it the appearance of having a “mask”.
Halloween Mask – this is another designer morph that originated in the late 90’s. Similar to the bandit, animals have thick black marking on their head which may express a pattern or “mask”.
APTOR – one of the ground breaking morphs in leopard geckos, the APTOR was created through a dedicated approach to line breeding, whereby the combination of several polygenic and recessive traits all come together to display a nearly patternless, highly colored animal. Lacking any true “patternless” gene, this is a man-made animal, using striped and reverse striped specimens to create an unstriped result. The Eclipse gene was discovered during the creation of this morph. Exceptional specimens should have thick orange head markings, a patternless body, and a high degree of carrot-tail.
Eclipse – the eclipse gene may be one of the most fascinating amongst leopard geckos. Seemingly tied somehow to the combination of reverse stripe and striped genes, the eyes will have some degree of black filling, sometimes in total. Specimens with trace amounts of black or partial filling are referred to as “snake eyed”. Determined simple recessive, the gene has been bred into all three albino lines, as well as most any other morph.
RAPTOR – adding and “R” to APTOR signifies the eclipse form of the morph. Simply an APTOR with eclipse eye pigmentation. Since it’s albino, the eyes will be red instead of black, but may be hard to see as such without good lighting.
Diablo Blanco – crossing the RAPTOR with the blizzard gene results in the “Diablo Blanco”. A solid white gecko with red eyes. At its simplest, it’s an eclipse blazing blizzard.
RADAR – the Bell albino version of the RAPTOR. An eclipse Bell albino.
Typhoon – the Las Vegas albino version of the RAPTOR. An eclipse Las Vegas albino.
Super Hypo Tangerine Carrot-tail – probably the most popular of all of the leopard gecko morphs was the super hypo tangerine carrot-tail. Selectively breeding for increased orange coloration over the span of fifteen plus years has resulted in some truly colorful, nearly solid orange geckos. There are several well known “lines” of tangerine, including the “Torrid Tangerine”, “Tangerine Tornado”, “Electric”, “Firefox” and “Gecko Genetics”. These are all believed to be polygenetic. Hypomelanism refers to the lack of black pigmentation over much of the gecko’s body.
Tangerine – many leopard geckos display orange coloration nowadays, which is mostly believed to be polygenetic in nature. However, there is a school of thought that there could be more than one tangerine genetic at play, specifically derived from selectively breeding the Tremper albino morph to express more orange. This particular tangerine, referred to as “tangelo”, may in fact be recessive. Test breeding over the next few years should illuminate the true nature of this trait.
Other “snow” morphs – there are three other occurrences of the faded, “snow” type traits in the hobby. The TUG snow, the GEM snow, and “line bred” snows. None are considered to be the same as Mack Snow, but TUG and GEM have been proven allelic in that they can produce super snow variants if bred to a Mack Snow specimen.
Of course there are combinations of just about all of the various morphs listed here, with the earliest being Murphy Patternless Tremper Albino (first produced by VMS Professional Herpetoculture), and the Blazing Blizzard (first produced by Jay Vella, Prehistoric Pets, with VMS also creating the morph right around that same time. )
This list is a work in progress, and will continue to grow as I find time to add to it…