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Discussion Starter · #1 · (Edited)
Hi All,

First, I am writing a massive paper/dissertation/research into the genetic disorders caused when interbreeding too far down a line to achieve a desired morph, breeding the same characteristics over and over again and mainly looking into the problems with six toed geckos.

Crested Geckos are polymorphic, this complicates things. This will make it harder to trace back unlike the leopard gecko, thus causing lots of long term problems in the future, this worries me.

This all stemmed from a few years back when I was looking into getting the Leopard Gecko and also my deep interest in human genetics.

I learned early on the problems with the Enigma morph is now proven to show some severe side effects due to inter breeding the smae genetics over and over again.

BUT

I want to learn, explore, and warn of any dangers/possibilites of breeding the crested gecko with, for example, six toes, or bred to the sister, and brother down and down. DOes this really cause harm? Where can we find evedence? It may not show in the first generation, may be not the second, but surely, there must be long term problems.

Their are so many risks, and lots of possible problems about to be caused, and I have a lot of information I have collated over the months that I want to put together, but I want to hear your opinions and thoughts and even any facts you have, and where they come from.

As a responsible, passionate and caring breeder, I want to ensure all of my crested geckos are healthy and that if anything like the above occurs, I will retire them regardless of if they are my best guy, or prettiest female, my personal opinion is I will not breed any crested gecko with an abnormality.

Under what circumstances would you retire your crested gecko?

Would you listen to people who advise? I have asked Allen Repashy for his input, and being a very busy man, I wait patiently for any possible information he may have, apart from his very vivid belief in only breeding healthy, normal crested geckos.

This is an INTEREST, and I am very very intrigued, so please, your thoughts are appreciated :)

Thank you.

Jacki.
 

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I think you already know my opinion on this as we have discussed it at length in the past.

Both Allen repashy and the folks at Pangea Reptiles as far as Im concered have the reply in a nutshell.
other long term breeders and keepers also have this viewpoint.


DONT

They do not want something they re-discovered and painstakingly studied potentially destroyed by bad genetics and whilst that is diffcult to do IF the abnormality is not visual with this 6 toe issue it IS visable.


If any crested geckos produce 6 toed babies immediately retire the parents and do not sell the 6 toed babies.

That way genetic abnormalities wont seep into the crested gecko breeding world. We are already working with a limited gene pool since not very many intial crested geckos were collected to produce what we have worldwide now.

Sadly many already do breed and sell 6 toed cresties. Just because a crested gecko looks ok on the outside apart from the 6 toes does not mean it carries 'safe' genetics.

6 toes is already a visual abnormality. Now these so called breeders say ' Oh its fine and until we have proof its a negative trait Im not stopping breeding'

I find that incomprehensable to be very honest. A bit like with enigma leo morphs. As long as you dont really know what the issue is and its not been proven to be horrifically detremental keep breeding. That attitude worries me. Surely if there is any abnormality fear you remove the issue to lessen the long term risk to the captive species.

I know exactly where I stand with this issue and it is firmly with the herptologists who have studied , bred and kept crested geckos for WAY WAY longer than any of us.


again one simple word..

DONT
 

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I think it is wrong, completely and utterly wrong

We have seen something like this with the Crufts fiasco, those poor dogs bred and bred to get desired traits and looks and it causes them massive health problems, pain and some even cause eventual agonising deaths.

I think if you have compassion and care about your animals that you will NEVER EVER do anything like that, these tiny little animals rely from us from the moment we buy/breed/hatch them to give them everything, its solely up the us keepers/breeders to give them anything they would ever need and to look after the responsibly, doing that isn't responsible it is cruel and disgusting, to breed these animals in to a state like that simply for own gain

NEVER
 

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in my opinion six toes is potentially the tip of the iceburg.
and it is worrying given that cresties have only been captive bred for just over 10 years that some bloodlines are showing abnormalities such as this.
unfortunately, many of the morphs we see today are only here because of inbreeding (which may be the fault of breeders in the states).
certainly though, if i was to breed a six toed crestie, i would retire the parents immediately. my advice to anyone buying cresties for breeding purposes is to not touch a crestie who has six toes or has any siblings, past or present, which such a deformity.
 

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i have a few 6 fingered geckos, and i also have eggs from brother to sister, they werent plesent especially as they did attempt to hatch after 60 somthign days...
 

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Discussion Starter · #6 · (Edited)
I think you already know my opinion on this as we have discussed it at length in the past.

Both Allen repashy and the folks at Pangea Reptiles as far as Im concered have the reply in a nutshell.
other long term breeders and keepers also have this viewpoint.


DONT

They do not want something they re-discovered and painstakingly studied potentially destroyed by bad genetics and whilst that is diffcult to do IF the abnormality is not visual with this 6 toe issue it IS visable.


If any crested geckos produce 6 toed babies immediately retire the parents and do not sell the 6 toed babies.

That way genetic abnormalities wont seep into the crested gecko breeding world. We are already working with a limited gene pool since not very many intial crested geckos were collected to produce what we have worldwide now.

Sadly many already do breed and sell 6 toed cresties. Just because a crested gecko looks ok on the outside apart from the 6 toes does not mean it carries 'safe' genetics.

6 toes is already a visual abnormality. Now these so called breeders say ' Oh its fine and until we have proof its a negative trait Im not stopping breeding'

I find that incomprehensable to be very honest. A bit like with enigma leo morphs. As long as you dont really know what the issue is and its not been proven to be horrifically detremental keep breeding. That attitude worries me. Surely if there is any abnormality fear you remove the issue to lessen the long term risk to the captive species.

I know exactly where I stand with this issue and it is firmly with the herptologists who have studied , bred and kept crested geckos for WAY WAY longer than any of us.


again one simple word..

DONT
See I have always agreed with you on this, and with the respect that the problems, long term, may not be apparant until at least two or three generations down, this should be prevented now should it not?

With the small amount of evidence and a lot of theoretical research, it is slowly proving that this genetic disorder, which is what it is, will cause long term effects and inhibit the future of the crested gecko.

This upsets me.

I think it is wrong, completely and utterly wrong

We have seen something like this with the Crufts fiasco, those poor dogs bred and bred to get desired traits and looks and it causes them massive health problems, pain and some even cause eventual agonising deaths.

I think if you have compassion and care about your animals that you will NEVER EVER do anything like that, these tiny little animals rely from us from the moment we buy/breed/hatch them to give them everything, its solely up the us keepers/breeders to give them anything they would ever need and to look after the responsibly, doing that isn't responsible it is cruel and disgusting, to breed these animals in to a state like that simply for own gain

NEVER
I do agree it is irresponsible, if I were still new to the crested gecko, and something like a six toed crested gecko hatched out, I would be so shocked and worried. I would be straight on to someone and asking about what I should do. This alone proves this is NOT normal.

NOT NORMAL - Yet it's pretty so we will breed it anyway?
NOT NORMAL - But it seems ok, it's eating and defecating and climbing fine?

I 100% agree that this should be prevented, and any crested geckos that have been knowingly bred from with six toes without knowing or trying to understand the complications is irresponsible and wrong. More research should be made, and surely, it would be better to retire the parents, or otherwise involved, and spend your time left over from not breeding them, looking into this long term possible problem.

If this problem is not addressed, or made aware, then we will be to blame for the problems later on.

I don't understand how anyone could call themselves a responsible, caring breeder, whether they breed in mass, or by few, using six toed crested geckos, when they don't even know, or understand why it has occured. There is NO real evidence yet, so in my honest opinion, this should stop until something has been proved. Is it not enough that is isn't normal?

in my opinion six toes is potentially the tip of the iceburg.
and it is worrying given that cresties have only been captive bred for just over 10 years that some bloodlines are showing abnormalities such as this.
unfortunately, many of the morphs we see today are only here because of inbreeding (which may be the fault of breeders in the states).
certainly though, if i was to breed a six toed crestie, i would retire the parents immediately. my advice to anyone buying cresties for breeding purposes is to not touch a crestie who has six toes or has any siblings, past or present, which such a deformity.
Tip of the iceburg is perfect. Whilst it is only apparant over the last few years, this should be prevented now.

Good advice, if you are to breed a six toed crested gecko, then I fully believe you are going to be responsible for some of the problems that will become more apparant in the future.

Unfortunatly, like many I know that inbreeding is required to gain a certain morph, but even I don't like this and this is why I would rather spend a long time finding the right female to put with my male. I aim not to be a "mass breeder" but to help bring up healthy, stunning crested geckos.

i have a few 6 fingered geckos, and i also have eggs from brother to sister, they werent plesent especially as they did attempt to hatch after 60 somthign days...
Thanks Freeky, can I ask, did the thought even cross your mind to breed these when older?

60 days is not long enough is it? I am pretty sure of that.

Thanks for your input so far guys, I appreciate it.
 

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I would be very interested to know what your current understanding of inbreeding depression is, and your definition of it. This will play an incredibly important role in your ability to write a structured response to the questions you want to address. Be very careful though, as from what you have written above, my understanding of your current definition suggests that it will restrict you.

I would also be quite reserved in any suggestions about this trait, as quantitative evidence does not exisit at this point, and it is very unlikely to ever exist.

The main point I would focus on here would be the effective captive population size, or the number of genetically 'destinct' individuals currently in the captive environment. My suggestion is that this is very very small. This will have great consequences for future breeding plans, and should perhaps be a focus for your article.

Can I ask the reason you are writting this paper, or for what?

Regards,

Andy
 

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Thanks Freeky, can I ask, did the thought even cross your mind to breed these when older?

60 days is not long enough is it? I am pretty sure of that.

Thanks for your input so far guys, I appreciate it.
no, it didnt i have morals, i woudl never breed bro to sis.
60 is enough
wanna see the babies who tried to hatch from the bro and sis?
my O tried to help them out, but foudn these....not what we were expecting
 

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This is quite classic premature termination, but what indication do you have that this is the result of inbreeding depression?

Andy
she gave birth to 4 or possibly 6 (cant rmemebr) but this was trying to hatch after 60 somthing days, crazy..
mind you so did the conjoined twins that i had (not from inbreeding)
 

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Discussion Starter · #13 ·
Reposted below...
 

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Discussion Starter · #14 · (Edited)
I would be very interested to know what your current understanding of inbreeding depression is, and your definition of it. This will play an incredibly important role in your ability to write a structured response to the questions you want to address. Be very careful though, as from what you have written above, my understanding of your current definition suggests that it will restrict you.

I would also be quite reserved in any suggestions about this trait, as quantitative evidence does not exisit at this point, and it is very unlikely to ever exist.

The main point I would focus on here would be the effective captive population size, or the number of genetically 'destinct' individuals currently in the captive environment. My suggestion is that this is very very small. This will have great consequences for future breeding plans, and should perhaps be a focus for your article.

Can I ask the reason you are writting this paper, or for what?

Regards,

Andy
Hi Andy,

First, thanks for your response. I will admit, my knowledge, most likely will be similar to others who have done similar research, is very limited. All I can offer is my own personal opinion based on theories I have read and from the "general understanding" of genetic disorders, or depression as you called it?

This makes it an intriguing subject for myself, and I also thought bringing it up may also spark an interest for any current, and future breeders (myself becoming a future small breeder).

Also what interests me is the number of captive bred crested geckos, the population you called it is small? Are you suggesting this might also be a cause of some future, underlying problems? Genetical problems? It's a lot to take in so bear with me if my questions seem vague.

I want to make it clear, I am very interested in learning how inbreeding MAY and possibly DOES cause problems if done improperly (and if done improperly, how is this? What is right about inbreeding, and if there is something right, can it be done with due care and responsibility?)

And also about the genetic disorder of the six toed gecko, if this is stemmed from inbreeding. Is this one trait/problem receeded from the inbreeding? Or is it just something abnormal that has ocurred? I understand this is another question that may fail to be answered due to some reasons I am aware, but unsure of the complications of the explaining it would take.

As for your last question, my "massive paper/dissertation/research" (I must admit, that was a silly thing to put) is in fact a personal research paper to which I want to create and use to hopefully understand genetics and abnormalities further so as to look into going back to university or further study so I can help to find some sort of evidence. I basically would like to aid in the research and knowledge so as to he;p understanding the genetics in a simpler way to further my interest in the breeding of captive bred crested geckos. I assume you could call this an interest more than anything at the moment.

This thread was meant as an insight as to what people like yourself, who, might I add, seem very clued up on a lot to do with breeding and a lot of the ups and downs that come with it and I have the upmost respect and worry I may embarrass myself "trying" but not finding any answers.. I am basically putting forth my ideas, my opinions and my questions so as to be corrected, and hopefully have some gaps filled in.

I understand this is NOT something that has a definitive answer, and something people will possibly, as you stated, never know a straight answer to, which means, do we then rely on morals? Opinions? Is it always going to be a back and forth cycle of conflicting theories?

Does this mean that by having this opinion, I am subconciously telling people in so many words they are wrong to breed six toed geckos? This means I am making an assumption therefore I cannot advise without facts. Pure morals though, this is different, and I am worried I will get morals confused with fact and end up in a mess! If I am wrong, I would very much like to see any other theories/morals and even possible facts people may have.

I also understand this may well be something I will be looking into, and researching for a long time, but being intrigued, I want to know what people think, or even better what people may well know.

I hope I have managed to at least answer some of your questions, to hopefully better you to help me understand something I find fascinating.

This is quite classic premature termination, but what indication do you have that this is the result of inbreeding depression?

Andy
Is this indication as in proof? I can imagine it would be very hard to trace this, this is where I need to broaden my inteeligence into genetics and breeding lines I assume, so that I may be more informed to respond to a question/opinion I have brought up to ensure I am not making any mistakes.

she gave birth to 4 or possibly 6 (cant rmemebr) but this was trying to hatch after 60 somthing days, crazy..
mind you so did the conjoined twins that i had (not from inbreeding)
It is pretty important to note at this point that it is incredibly unlikely to see F1 generation fitness reduction in full sibling crosses.

Andy
The above here is something that confuses me which is why I would love to hear/see any links you may well have to point me in the right direction.

I am fully aware, I may have jumped two miles over the line in my assumption and opinions, and should start at the beginning, but like everything, I have tried to look at what I have, put that forward, and realised I need to know more before assuming any more theories.

I really appreciate the replies, and thanks for any help.

Jacki.
 

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purple vixen you have made a very interesting thread, I look forward to seeing more as you progress. Having only recently come into cresties I am very interested in any potential genetic disorders. I could make a list for different species/morphs of snakes but lizards is a whole new ball game to me.

Everything comes with time, cresties being new to the scene as such. I know from my own stand point I wouldnt consider breeding anything with 6 toes and am trying currently to source my base breeding stock from several areas inc US, europe and the UK in the hopes of getting as much diversity as possible in such a small gene pool.

It will be interesting to see what comes out in the future as genetic and what is incubation fluctuation based.
 

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Inbreeding depression is a reduction in fitness caused by becoming homozygous for a deleterious allele(s) at one or more loci. What is interesting here is that this is not dependant on full sibling breeding per se, although this can create this kind of homozygote.

The first major thing to note is that heterozygote 'carriers' of a deleterious mutation show no phenotypic characters of the trait. This makes it almost impossible to know if an individual is carring a deleterious mutation or not. It is also worth noting here that this can be complicated by being polygenic, and not controlled by simple mendelian inheritance.

With these definitions out of the way, it is probably best to move on to what most people tend to consider as 'inbreeding': breeding between to full siblings. Is this potentially dangerous? The answer unfortunately is not simple, but I will attempt to give you a good overall impression, by looking at a series of scenarios.

1) Parent A is a carrier & parent B is wild type:
NB// this trait is controlled by a single loci, and subject to simple mendelian inheritance.

- To simplify things I we should consider 'W' to be wildtype or normal and 'M' to be the non wild type or mutant allele.

Parent A-1 Parent A-2
(W) (M)
Parent B-1(W) WW WM
Parent B-2(W) WW WM

The F1 generation offspring have a 50% chance of being homozygous for the wild type allele, and 50% (per hatchling) of being heterozygous for the mutated allele.
If you then choose two siblings at random from this generation and breed them together:
a) F1 sibling A is homozygous W & F1 sibling B is a carrier (WM):
The resultant F2 offspring are the same as the previous generation.

b) F1 sibling C is a carrier & F1 sibling D is a carrier (both heterozygote, single copy) parents are not full siblings:


The table below show the F2 generation outcomes:

Silbling C-1 Sibling C-2
(W) (M)
Sibling D-1(W) WW WM
Sibling D-2(M) WM MM

basically this shows that if you breed two carriers together, 25% will become homozygous for the deleterious alelle, 50% will be carriers and 25% will be homozygous wild type:

If you then take the next generation (F2) of full sibling pairings:
1) Sibling A is a carrier & Sibling B is wild type

Sibling A-1 Sibling A-2
(W) (M)
Sibling B-1 (W) WW WM
Sibling B-2 (W) WW WM

F3 gen: Again 50% Carriers and 50% WT

2) Both siblings are carriers:

Silbling C-1 Sibling C-2
(W) (M)
Sibling D-1(W) WW WM
Sibling D-2(M) WM MM

F3 gen: Again 25% will become homozygous for the deleterious alelle, 50% will be carriers and 25% will be homozygous wild type.

3) Sibling E is homozygous M and Sibling F is homozygous W

Silbling E-1 Sibling E-2
(M) (M)
Sibling F-1(W) WM WM
Sibling F-2(W) WM WM

F3 gen: 100% heterozygote carriers.

4) Sibling G is homozygous M and Sibling H is heterozygous (WM):

Silbling G-1 Sibling G-2
(M) (M)
Sibling H-1(W) WM WM
Sibling H-2(M) MM MM

F3 gen: 50% of the offspring will heterozygous carriers and 50% will homozygous M.

You will then see that in the next generation, breeding two homozygous M individuals, will give you 100& homozygous M individuals.

This is an over simplified scenario, but what is clear is that it is certainly not the case that full sibling pairings are always by default negative, but neither can it be said that they are not. What is worth noting, is that mutations are rare.

I can not really discuss morals or ethics with you, they will vary between individuals, and it will always be down to personal choice.

Ok, a further level of complication, the 'genepool' or the effective population size. The entire population of crested geckos (in the US, Europe and the UK) came from a very limited number of individuals, which effectively makes all captive individuals very recently related. If you consider this, it can effectively move you through the inbred generations without any full sibling pairs.

Are there other problems with a restricted genepool? The simple answer is yes, fixation of a deleterious allele can cause real issues for the entire population. There is a little more information on this here:

http://www.reptileforums.co.uk/lizards/174682-inbreeding-depression-facts.html

As I have said, most of the information here is over simplified, or is the simplest scenario. It is pretty unlikely that a deleterious allele will be simply inherited.

Another thing to think about here is where inbreeding depression will occur. By this I mean: Pre-laying (creating effectively infertile eggs), Pre hatching (effective early termination) or after hatching in the offspring.

There is another thread which you may find useful here:
http://www.reptileforums.co.uk/lizards/341185-inbreeding-have-we-gone-too.html

Regards,

Andy
 

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If the extra toes mutation in the crested gecko is due to polydactyly then this should be relatively easy to trace back through the parents lineage as it is autosomal dominant?
 

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If the extra toes mutation in the crested gecko is due to polydactyly then this should be relatively easy to trace back through the parents lineage as it is autosomal dominant?

Polydactyl from the latin 'many fingers' is a little confusing in this sense, as you are referring (I assume) the Human condition, and I have seen no evidence to suggest any similarity between the two conditions. That aside any conditon which creates extra digits can be considered polydactyl.

Andy
 

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To start with i would like to thank everyone who has comented on this post, and to purple vixen for starting this post. Genetics is something that facinates me and I am passionate about learning.

I would like to eventually move on to study genetics at university but at present the opotunity is not available too me. Because of this passion I decided to start with breeding crested gecko's (a species I adore). I am making it a hobby of my to note down as much as I can about each baby hatching and all parents to see how the genes are passed down through a polymorphic species.

I am far less "in the know" than alot of people here but it has really facinated me reading this thread.

What other abnormalities have been noted due to inbreeding in crested gecko's?

Mutations are what cause genetic variation so mutations can be good for a species. But where do people draw the line at useful mutations, and how can we be certain that these mutations are caused by inbreeding.

thanks again for starting this thread, its been a good read :2thumb:
 

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Polydactyl from the latin 'many fingers' is a little confusing in this sense, as you are referring (I assume) the Human condition, and I have seen no evidence to suggest any similarity between the two conditions. That aside any conditon which creates extra digits can be considered polydactyl.

Andy
Sorry, I don't follow - Confusing how?

I wasn't referring specifically to the human form but to the genetic condition in general, as it has been found that the same mutation that results in the extra digits in humans is apparantly responsible for the same effect in various other species (horses, cats, newts, mice and a few others I can't recall) and in each case the mode of inheritance appeared to be the same. I can't remember what the exact mechanism is (seem to remember it's to do with a disruption of the signalling molecules affecting the lower limbs distal growth plate - would need to go and check to be sure), but the point I was making - not very clearly it seems - is that it is not unreasonable to assume that the same mutation is in effect in the case of these crested geckos, in which case a systematic review of the affected animals' lineage should identify where the mutation originated from.
 
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