“Natural” vs. “Man-made”: Facts and Myths about Morphs in the Leopard Gecko

There frequently seems to be a lot of emotionally very heated discussions among leopard gecko breeders about the production of specific colour-morphs vs. wild-type geckos. In a few forums, the community has split into groups that value wild-type geckos above everything else, and have great trouble respecting colour-morph breeders as well as people who breed and enjoy both varieties. Many of those discussions are lacking verified information, and generally tend to create more confusion than provide answers.

This article will deal with the topic and provide some relevant scientific and genetic facts which will hopefully be helpful to newcomers, and also assist advanced keepers to find out the facts behind the myths.

Here are some of the most frequently asked questions:

Are morphs generally sicker or “weaker” than wild-type leopard geckos?

General weakness and declining fertility in some breeding groups are genetic traits which are not bound to a specific phenotype, but are a result of a loss in the gene mass caused by improper selective breeding, often seen in conjunction with strong inbreeding.

To put it simply: If you have a very small breeding group of geckos, only breed them and their offspring to each other for many generations, never add “new blood” resulting in continual inbreeding, use the weakest, smallest, thinnest and least fertile animals for breeding – you will almost certainly create a colony of “sick and weak” offspring. It doesn’t matter whether these animals are specific colour-morphs or wild-type leopard geckos.

However, if a breeder manages his or her colony carefully, is willing to learn about genetics, gene loss in a colony etc.  and only uses the strongest, most fertile animals for reproduction – the gecko colony will bloom and be able to create healthy offspring.

The question of whether a gecko is “strong” therefore is not simply based on “wild type” vs. “morph”, but is related only to its genetic background and how inbred the particular animal is.

I  bred wild-type leopard geckos exclusively  from 2000- 2005, after which I switched over to breeding colour-morphs and continue to do so.  Due to my study of veterinary medicine as well as my own personal experience as a breeder of both wild-types and morphs, I can say the following:
In my years as a breeder I have seen fantastic wild-type colonies as well as questionable breeders producing “weak” colour-morph babies. On the other hand, I have also acquired  a lot of excellent and robust colour-morph geckos, as well as inbred wild-type babies (namely  a certain line of macularius and one bloodline of afghanicus)  that, due to their inbreeding level and general weakness, never reached maturity despite excellent veterinary care. .

But why? Well, both “populations” (wild-types and colour-morphs) of leopard geckos have limited genetic diversity in captivity — their gene pool will never compare with those geckos living wild and free  in nature. In addition, our husbandry methods allow weaker geckos to survive and reproduce, while nature always and only selects the most healthy ones.

As a result,  geckos’ health, endurance, fertility and strength depend entirely on how the breeder selects and manages the colony.
Face it: There is no “better” or “worse”genetically when comparing wild-types and colour-morphs. Period ;-).

 Colour-morphs emerged through inbreeding. Is inbreeding bad?

The term “inbreeding” (meaning the pairing of closely related individuals) is often used in a negative way, and confuses many people in the community.

The experience over the last 20 years of leopard gecko breeding has shown us that leopard geckos, unlike some other species, seem to tolerate more inbreeding without showing any negative signs. Therefore, breeding siblings or parents back to their offspring are methods often used by breeders. If carried out from time to time, this method can be useful to fix certain genetic traits. However, too much or the wrong selection can cause genetical damage. Typical signs often reported for excessive inbreeding in a colony include:

• a significant number of small sized hatchlings & adults
• low body weight & the impossibility of creating proper fat reserves on a normal diet
• lower ovulation-rate
• lower egg production rate
• higher risk of egg binding in females
• slow growth

In general, I think it is fair to think of inbreeding as a double edged sword:
For colour-morphs, inbreeding is like spice or salt in a soup: A little bit is the basis for all colour-morph mutations or lines to appear (without inbreeding there wouldn’t be leopard gecko colour-morphs, different cat and dog breeds, etc.).
It can also help an advanced breeder to detect genetically undesirable traits in the colony, fix specific traits like a specific pattern (for example any pattern like red stripe, etc.), as well as character or fertility in a colony (fertility is said to be genetically inherited in dogs by something above 20% — cf. “Genetik des Hundes” by Inge Hansen).

So naturally it could be a useful thing to improve the fertility of a line by fixing this feature via line breeding (which is a milder form of inbreeding that mostly uses breeding partners that are not too closely related). Line breeding for fertility can theoretically improve the fertility of a breeding group in only a few generations  IF  the breeder has advanced knowledge and therefore knows what he or she is doing.
On the other hand, improper line breeding  and especially strong inbreeding (mother-son, father-daughter, siblings), as well as any kind of inbreeding without care can have fatal consequences if you haven’t done your job properly, and therefore is a high risk especially for new breeders. Consequently,  I do not recommend these techniques for a beginner or any genetically inexperienced breeder at all. In my opinion, doing your homework and keeping proper overview over the gene pool of a colony are necessary tools for safe inbreeding or line-breeding.

Even in our own stock, Dragoon Gecko focuses on doing outcrossings and adding new blood on a regular basis with great results regarding fertility, general strength and health.

Doing your homework very carefully is essential for an optimal and desired result. This can only be achieved by studying about the theory of genetics,  and/or seriously considering a consultation with an expert in genetic management (e.g. Dragoon Gecko offers such services for individual genetic coaching, and has already helped many colleagues to reach their goals).

In contrast, I personally see no sense in doing inbreeding at all in a wild-type project , as the main focus here should be to try to preserve and maintain as much genetic diversity as possible in the colony, with inbreeding naturally only causing unnecessary gene losses in the process.

For an inexperienced breeder being confronted with inbreeding difficulties or unidentified problems, the best solution usually should be to consult some experts to find an answer to the problem, and evaluate whether the animal(s) in question are ethically acceptable to be used for further breeding. The next step would be carrying out an immense outcrossing program in order to get more unrelated genes into the colony which is for sure a much safer way than continued inbreeding. It will also be important to make sure the offspring from such a “problem” project will be kept as pets only and not find their way in the market to “taint” other precious bloodlines before the problem is solved – it will help you to keep your customers happy, and your reputation intact.

As a consequence, I can highly recommend that every breeder, wild-type and colour-morph alike, should do their homework and have  strict quality management as described in my article (Selection of Breeders and Quality Management in Leopard Geckos) in order to prevent such problems right from the start, and to build the best foundation possible for vital and strong offspring that will satisfy not only you, but also your customers.

What most people don’t realize: Inbreeding can NEVER “improve” your trait or line. It only is able to increase the visibility of the genotype (i.e. the summary of genes present) that you already have! Keeping this simple truth in mind helps the advanced breeder to decide when inbreeding is necessary, and when outcrossing is the better way.

Whenever you decide to inbreed, naturally only the strongest, healthiest and most fertile animals should be used, as anything else raises the risk of causing a disaster.

In order for the beginner to create a strong and colourful line, 90%  of the time the best and most successful way is to buy an excellent gecko and use it to bring its fantastic genes into your breeding colony rather than focusing on inbreeding!!

But has all of this talk about inbreeding anything to do with the hot topic “wild vs. colour-morph”? Indeed, it does: While maintaining that all colour-morphs emerged from inbreeding (and therefore should be “weaker” than wild types), many people fail to realize that, as discussed above, wild-type breeding colonies can also be strongly inbred, and therefore suffer the very same symptoms as “bad colour lines”.

In the end, it is again the breeders and their selection of breeding stock that counts and makes a difference! Trust in a breeder and their program is therefore essential for making the right choice of where to buy your geckos from.

Are colour-morphs generally more inbred than wild-type leopard geckos?

This depends:  Inbreeding differs in every line and with every breeding stock.  A breeder that outcrosses regularly and has a huge breeding population may provide a larger gene pool for the animals than others that do not outcross or have a very small colony.

If you compare our colour-morph population in general with the significantly fewer pure wild-type leopard geckos in captivity (since importing new blood from the wild is difficult), it surely is a given fact that those “wild”  lines are inbred to at least some degree. Leopard geckos living wild in their home countries such as Pakistan, India and Afghanistan will surely be less inbred and therefore provide a larger pool of genes than any wildtype or colour-morph leopard gecko bred in captivity! But this is a natural effect which happens with any species bred in captivity, and does not automatically mean the animals are weaker or sicker if they lose a part of their genetic background mass. The important point is not to let this gene loss happen to a critical degree. We will never be able to prevent a gene loss in a population 100%. But we can do our best to save as much as we can by using the techniques described above.

What is the sense in crossing wild-type and colour-moprhs?

In some forums, the idea of “mixing” wild caught animals into colour-morph lines seems to upset people — they claim that it “may be better keep the lines pure”.  As all leopard gecko colour-morph lines have originally emerged from wild caught animals however, this thought doesn’t make much sense.
In the early years of breeding, wild caught geckos from different habitats and countries were collected, mixed together to be housed in big groups by the importer, and finally sold to the pet shops. We can say with almost 100% certainty that the story of our “modern” designer geckos has its origin in more or less accidentally crossing different local wild-type forms of the leopard gecko.

The main goal of a wild caught x colour-morph cross is to enlarge the gene pool and to add precious genes into the colour-morph lines. As a result, such babies will naturally possess a larger gene pool than either of the parents (wild type or colour-morph) and therefore make very valuable breeders. Dragoon Gecko for example has successfully crossed Montanus  wild caught animals into one of our Raptor lines- resulting in Raptor babies that are significantly bigger at birth, and have a better growth rate than “pure” raptors. In our eyes, making sure our babies hatch out as strong and healthy as possible should always be a top priority, especially if we consider animal welfare. Producing offspring with less than our desired outcome in general health just because of  personal beliefs (no scientific paper exists to date that claims wild-blood crosses to be “wrong”, and probably never will be 😉 ) is not the way we choose to go.

As all colour-morphs originally emerged from wild-type leopard geckos, I personally see no reason at all not to cross them. People who wish to breed only wild-type geckos can certainly do so, as such animals may be used one day for an introduction program back into the wild.
As responsible breeders, they should also allow colour-morph breeders to acquire some of their offspring in order to outcross them into their lines and keep them healthy.

It cannot be stressed enough that responsible wild-type breeders should always be aware of the fact that the general population of wild-type geckos in captivity is limited, and therefore they also have to deal with inbreeding effects and gene loss. The wild-type breeder community should therefore prevent gene losses as best as possible by exchanging their wild-type animals as much as possible, and keeping track of each animal’s genetic origin. However, they probably will still depend on at least small amount of wild caught animals in the long term (we’re talking in decades here) in order to keep their lines “pure”.

As a consequence , both sides should respect and tolerate each other, as we are all sitting in the same boat:  If imports from the original habitats would be 100% prohibited, and if the wild-type breeder population would not be big enough worldwide in captivity to prevent a massive gene loss across generations, the wild-type population could one day collapse in comparison to the colour-morph population which is so immense worldwide already that it does provide sufficient genetic diversity to prevent such a breakdown – if the breeder community selects carefully and does not mismanage the genetic diversity that it has.

As we  can see, every breeder (no matter whether of wild-type or colour-morph) is playing his or her own important role in this gigantic puzzle, and  together as a respectful and supportive community we’re having great chances keeping both forms alive and healthy for our children and grandchildren to see and enjoy!

In Conclusion

Science and breeding results for recent decades throughout the world have clearly shown that no one can claim either the wild-type or colour-morph to be superior. In both types of colonies, we will find each end of the spectrum. It is and always will be every single breeder’s choice where on the spectrum (low quality vs. strong and healthy animals) they will end up.

I deeply hope that more and more people will be able to see this topic from a more scientific point of view, and are willing to focus on what is best for our beloved leopard geckos as opposed to their own personal opinion about the topic.

 

Lead Photo Credit: Catherin Arsenault photos