Green Tree Python Color and Pattern Morphs
Perhaps nothing about chondros is as fascinating or mysterious as all the various color varieties, and the way the neonates develop these adult colors. The general information presented here will answer some basic questions that are frequently asked, and some of the facts (and fallacies) regarding this subject will be addressed. This page deals with captive bred color morphs. For information about the Geographic races and localities of GTPs, please see Geographic Races.
Some definitions may be in order so that no confusion will result from the terms as used on this page. I define a Morph as a definable color and/ or pattern trait that makes up a permanent adult appearance. Phase denotes a color or trait that appears for a while but may or may not be permanent, such as a temporary juvenile color. Designer indicates a morph that is not normally naturally occurring. High end refers to any chondro that is an outstanding example of its kind, regardless of whether it is a naturally occurring or designer morph. The group of morphs discussed below is not an exhaustive list, but it covers the common ones.
The genetics discussion is not intended to be an exact primer on all things related to the subject, but rather is intended to communicate the important and applicable elements of heredity as they relate to chondros.
For a much more in-depth discussion about morphs and genetics, as well as dozens of beautiful color plates illustrating these beautiful animals, order my book, The Complete Chondro.
Let me state up front that I am not a geneticist, and my understanding of basic genetics is based on what I have learned from others. A good link for information is The Genetics Wizard. The page with word definitions is especially helpful. I can, however, make many valid observations about how genetics and heredity issues relate to CB chondros.
GTPs are animals that in many ways don't conform to commonly accepted principles when it comes to predicting the results from breeding adults of various color morphs. To put it simply, the popular color and pattern morphs we see most often have not demonstrated themselves to be either dominant, or simple recessive traits, in the way that they are with many other reptile morphs. (See the Genetics Wizard link above for term definitions if you are not familiar with them.) It's important to emphasize that this does not mean that such traits are not "genetic", but rather that they are not expressed in offspring with a predictable percentage of results, and therefore cannot be guaranteed to manifest themselves in offspring. All traits are "genetic" in the sense that they are controlled by the DNA map of the organism. What most of us mean by "genetic" is if the trait is heritable - able to be predictably passed down to offspring.
For example, the popular high yellow morph has been demonstrated to be a heritable trait. But, it is not the result of a simple recessive gene, like albinism is in many snakes. Two albinos bred together will produce all albino offspring. An albino bred to a normal mate will produce normal looking offspring that carry the albinism gene, and are said to be heterozygous for albinism, or "hets" for short. But it doesn't work this way with high yellow chondros, or with high blue, or calico, or other chondro morphs. Pairs of these kinds of color morphs may or may not produce offspring with the desired traits, and normal looking offspring are not considered to be hets, although they can be assumed to be carrying the genes of the family tree. This means that the offspring may produce the desired morphological traits in their own babies when they are adults, but not with the mathematical probability that true hets would.
The good news is, it has been demonstrated that selectively breeding for certain color and pattern traits does strengthen them over time, and often each generation increases the percentage of offspring from any given clutch that will display the desired traits. Some bloodlines, such as the well-know high yellow "Lemon Tree" strain, have shown themselves to be potent, producing some high yellow offspring even when bred to a non-Lemon Tree mate. Other morphs are still in the early stages of being developed and proved. What are the odds of getting what you want when buying offspring from high-end morph bloodlines? It's my opinion that quoting percentages is based more on wishful thinking, than on solid evidence. The best indicator of future results is past results, and unfortunately many of these animals are not pedigreed or kept track of very well, so it can be difficult to see verified results over a reasonable length of time. Still, some breeders can show photos and give references regarding what their stock has produced in the past.
To be really sure of what you are getting, it's necessary to buy yearlings or young adults that have already color changed. Of course, this is the expensive way to go, as individual pythons that show highly sought after color traits are very expensive, and rightly so. Accordingly, most buyers choose to spend their money on offspring from bloodlines they like, and take their chances with the end results. The worst case scenario is that the collectors will have animals that still have the potential of reproducing the traits, even if they themselves don't show them. Buyers need to understand that this is what they are paying for when buying high end neonates - the chance at getting spectacular adults, and the certainty of obtaining animals from the bloodline. If the results from some morphs could be guaranteed to show up in the offspring, they would cost a lot more!
The bottom line here is to ask to see past results from the bloodline when considering purchasing expensive offspring from select morphs, and to take with a grain of salt the frequent sales claims that accompany many classified and dealer ads. Breeding a blue female does not mean that "these babies should make nice blue adults". The best color morphs come from breeders who are selectively breeding quality animals with years of residual genetics involved in the bloodlines.
Ontogenic Color Change
Neonate Morelia viridis hatch as yellow, maroon, or brown babies. Although the biological reasons for these color phases are not known, we do know that the hatchling color of the parents directly influences the colors of their offspring. All yellow, or all red, clutches result from pairing adults that had these baby colors, and mixed parents can and do throw mixed colors of offspring.
Baby chondros undergo their color change at about 6 month to a year in age, although I have seen this begin as early as three months. The exact cause and process that effects this change is not fully understood, but it is definitely age and growth related. The timing and nature of the color change does not seem to be influenced by external stimuli.
Babies can change quickly, even overnight, but most take several weeks or months to complete the change. With the exception of specimens of the Biak Race, the changes are usually permanent once they slow down or cease. Biaks often take several years to fully change into the permanent adult colors.
The color change can be drab or spectacular, with dark babies often exhibiting amazing and beautiful colors and patterns along the way. Blue colors often take the most amount of time to develop, and it may be several years before the blue stripes, dorsal markings, and other highlights fully manifest on specimens having them. These markings often look purple as the animal becomes a young adult. White markings are often the first color to develop.
The Calico Morph
In my opinion, this color and pattern morph is the most beautiful and interesting of all the chondro variations. Animals of this morph are noted for three things: an unusual and visually striking display of different colors randomly and evenly scattered over the entire length of the snake; a pixel-like pattern that resembles a computer monitor's grainy appearance when viewed too closely; and a unique neck pattern that stands out from the rest of the snake. The morph was started by a founder male produced by trooper Walsh and acquired by me in 1994. It is worth noting that the male was not produced by mixing certain locality traits to develop the results seen. The calico pattern did not evolve and improve from successive breeding - it just spontaneously showed up. This is why certain genetic traits are called "spontaneous mutations".
It should be noted that some Biak Island type animals often go through a yellow or orange phase, along with large, bold markings, that can last for a year or two as they develop the more normal adult green color. These are sometimes labeled "high yellow" or "calico" at times by dealers, but in fact they are neither.
For the complete history of this morph, and my work with developing it, please see The Fine GTPs Calico Project.
High Yellow Morphs
This wonderful chondro morph is the favorite of many collectors, and the best specimens and bloodlines command very high prices. The Lemon Tree bloodline in particular is noted for producing some spectacular specimens with bright yellow coloration. It is also a potent bloodline, and my experience is that about one third of the offspring from Lemon out-crossed clutches will attain true high yellow adult coloration. This is likely to improve as the morph is selectively bred using other yellow adults. Ophiological Services also has a high yellow line, and several other breeders are working with this morph.
Most high yellow aficionados feel that there is some Biak blood at work in high yellow bloodlines, and unlike their pure-blooded island relatives, the captive high yellow bloodlines do not take a long time to change from baby colors to the adult colors. Especially beautiful, in my opinion, are the yellow adults that also have dark green on them. While no one can deny the initial dazzle of all-yellow specimens, I find that animals with contrast and pattern are more interesting.
High Blue Morphs
Once considered very rare, blue chondros are now known to be fairly common. This is especially so of hormonal color-shifted females. Such females develop the blue color during the first or second pregnancy. This may then become the permanent adult color of the female, or she may revert to her original green color. Some females become more blue with each ensuing pregnancy, and will finally keep the blue permanently. It has not yet been clearly demonstrated what percentage of female offspring from such blue female adults will turn blue themselves, nor is there much evidence that pairing a true blue male with a hormonal blue female yields consistent results.
"True blue" chondros are animals of either sex that have a high percentage of blue pigment, sometimes to the extent of appearing nearly solid blue. These high blue chondros are not nearly as common as the blue phase females are, and are highly sought after by breeders and collectors. The males pictured above are both examples of true blue morph chondros. This color morph is not limited to males, and there are examples of blue females that were so before undergoing any breeding periods. It is not known if crossing blue males with either type of blue female produces better results; to date I have produced an outstanding true blue male from both kinds. The occurrence of true blue offspring within a given clutch seems to be minimal regardless of which kind of female is used.
I think that blue adults of either type, and of both genders, are very beautiful and desirable. But there is no denying the appeal and relative rarity of the true blue specimens.
Blue morph adults are best displayed under full spectrum lighting brings out the full beauty of their colors. Normal florescent or yellowish incandescent bulbs will distort or mask the blue colors.
Blue Mite-Phase Morph
The term "mite phase" was coined by GTP lover John Romano, and is used here as an exception to the definition of phase given above. "Phase" usually denotes a temporary stage of development, and many of these chondros retain the dark speckling into adulthood. While I don't find the black speckling to be anything special in and of itself, it is visually striking when combined with blue, and would be fabulous on a yellow animal as well. It is still being established as a reliable breeding trait, and bloodlines with this trait have already demonstrated a tendency for it to be potent. Interestingly, there are yearlings who show heavy speckling during the middle stages of color change but retain little or none of it as adults. There is no solid evidence linking multi-generational mite-phase chondros with certain specimens from highland localities.
Photo courtesy of Damon Salceies
Damon Salceies hatched the first living albino Green Tree Python in January of 2002. He kept the animal a secret until making a big announcement at the National Breeders Expo in Daytona, FL in August of that year. Salceies had been working with a group of locality-specific Meruake animals obtained from a wild pairing bred by Tracy Barker. Two albinos were produced in the Salcieis clutch, but one perished from a skin infection. The other has thrived and is undergoing its color change in 2003.
There is no doubt that the production of this albino will impact designer chondro breeding for many years. It is likely that each natural and captive-produced morph will make an exciting new variant of the albino form.
There has been much speculation about whether other Merauke adults from the Barker F1 clutch might be heterozygous for the albino trait. Since two albinos were produced in the Salceies clutch, it is likely that the parents are hets. A spontaneous mutation from normal parents would likely have resulted in only one albino offspring. Are siblings to the albino baby's parents het as well? This must be proven by selective breeding before conclusive statements can be made. At best, they are "possible hets". As an owner of an F2 male from this group, I am hopeful the the sire, owned by Trooper Walsh, is eventually proven to in fact be a het for albino. Thjis would make my male a "possible" (50% chance) het as well. However, it can not be claimed that any F2 offspring are "possible hets" until the F1 parents are verified.
Regardless, the existence of an albino chondro has made the world of designer breeding a more exciting place, and it was pretty exciting already!