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  #1 (permalink)  
Old 14-08-2017, 03:41 PM
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Default DNA Gender Confirmation

Can the gender of a tortoise be determined by a tissue sample - if so how? I am not talking about temperature dependant sexing - I am looking for guaranteed identification.

The long and short of it is I want 2.3 or 2.4 of a particular species but unfortunately the adults are not readily available and outwith my budget.

The alternative is to purchase a group of youngsters (unsexable) and hope for the best. It would be just my luck that I spend 3-4 years growing on (and getting attached to) a group of animals that turn out to be all males!!
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CAVEAT: any opinions expressed are my own and based on my own experiences and observations - whether you agree or disagree with them is up to you!!

IMPORTANT: if the health of your animal is giving you cause for concern, absolutely seek a second opinion from fellow forum members - your first opinion however should be that of a suitably qualified veterinarian!!

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Old 15-08-2017, 03:04 AM
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Yes, it can be done.
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Old 15-08-2017, 08:21 AM
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That was helpful - how?

Quote:
Originally Posted by Stephen P View Post
Yes, it can be done.
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CAVEAT: any opinions expressed are my own and based on my own experiences and observations - whether you agree or disagree with them is up to you!!

IMPORTANT: if the health of your animal is giving you cause for concern, absolutely seek a second opinion from fellow forum members - your first opinion however should be that of a suitably qualified veterinarian!!

EXPECTED 2020: SNAKES: Angolan, Sumatran and Royal Pythons
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Old 15-08-2017, 08:41 AM
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I'll find out and let you know.
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Old 16-08-2017, 08:40 PM
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I was told by my vet a few years ago (there could be new scientific developments since) that at a young age (before they show any sexually dimorphic characteristics) there is no way to tell the difference between male and female tortoises as apparently the gender they eventually become depends on the number of males and females they are exposed it in their environment. (eg. If they are exposed to many females, they may be more likely to be male) I am sceptical as to how true this is but apparently this was the leading theory in the veterinary practice. He was saying that in theory because there is no difference in genetic code, they actually had the potential to switch between genders if there is a shortage. This I do not believe. As i say, i don't know how much of that (if any) is true, but take what you will from it
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Old 16-08-2017, 09:18 PM
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I was told that this wasn't possible by my vet as apparently there's no genetic difference between tortoises however, I'm not exactly sure how much truth that holds as something would have to code for the sexual dimorphism. If you can you would need to take some kind of DNA sample (skin/tissue) and send it to the right reptile laboratory for genetic sequencing.
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Old 07-09-2017, 03:18 PM
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So by your vets logic, upon hatching in the wild the young tortoises would disperse into the local area and depending on how many individuals they encounter over the course of the next year or two would directly influence what sex they choose to be?

I can absolutely see the benefit of such an adaption but I very much doubt it to be true.

What is more likely in my opinion, is that the mother can influence the sex of the young by how deep she lays her eggs. If pre-lay she were to encounter more males for example she may wish a higher ratio of females rather than adding to the already saturated male population. As I said, this to my mind would be more logical and believable.

Any tortoise breeders wish to chime in?

Quote:
Originally Posted by Wolfy115 View Post
I was told by my vet a few years ago (there could be new scientific developments since) that at a young age (before they show any sexually dimorphic characteristics) there is no way to tell the difference between male and female tortoises as apparently the gender they eventually become depends on the number of males and females they are exposed it in their environment. (eg. If they are exposed to many females, they may be more likely to be male) I am sceptical as to how true this is but apparently this was the leading theory in the veterinary practice. He was saying that in theory because there is no difference in genetic code, they actually had the potential to switch between genders if there is a shortage. This I do not believe. As i say, i don't know how much of that (if any) is true, but take what you will from it
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CAVEAT: any opinions expressed are my own and based on my own experiences and observations - whether you agree or disagree with them is up to you!!

IMPORTANT: if the health of your animal is giving you cause for concern, absolutely seek a second opinion from fellow forum members - your first opinion however should be that of a suitably qualified veterinarian!!

EXPECTED 2020: SNAKES: Angolan, Sumatran and Royal Pythons
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Old 07-09-2017, 03:34 PM
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I've not got any information that would be helpful, but I have been thinking lately whether ultrasound would be able to determine sex, using it to check the gonads perhaps?
It was more of a thought for sexing my Corucia, but don't see why it wouldn't work other stuff, if at all possible.
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  #9 (permalink)  
Old 07-09-2017, 03:40 PM
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It can be done, however costs may be expensive because its not many people actually run sexual testing on tortoises.

Simply put by using a blood sample they can work out which sexual chromosomes the individual have. Some reptiles have ZZ for males and ZW for females, and other species will have XY for males and XX for females. However new research is starting to come out that in some species that are temperature dependent sexual determination that one sex can be either XY/XX and the other one just XX.

Disclaimer, genetic work I have conducted in the past doesn't include sexual work due to sexing done due to morphological characters. This will be the case for a lot of species.

Best thing to do is try ask around any University that do work on the species in question and whether they have done any genetic work to ask this question. If you can say which species I may be able to help.

Quote:
Originally Posted by Tarron View Post
I've not got any information that would be helpful, but I have been thinking lately whether ultrasound would be able to determine sex, using it to check the gonads perhaps?
It was more of a thought for sexing my Corucia, but don't see why it wouldn't work other stuff, if at all possible.
Just an extension to this, it may be possible for this to happen but will depend on the species and the age of individual. But also how experienced the operator is on tortoises.

Cheers,
TM
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  #10 (permalink)  
Old 07-09-2017, 04:44 PM
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Can you recommend anyone or any establishment that offers this please?

The species in questions is the Egyptian Tortoise: T. kleinmanni - the long and short of it is I have the opportunity of acquiring some unsexed youngsters via the European Studbook - knowing my luck I would end up getting attached to them only to discover that they are all males.

By having them sexed at a young age I have more chance of exchanging them with other keepers.

Quote:
Originally Posted by Tortoise Man View Post
It can be done, however costs may be expensive because its not many people actually run sexual testing on tortoises.

Simply put by using a blood sample they can work out which sexual chromosomes the individual have. Some reptiles have ZZ for males and ZW for females, and other species will have XY for males and XX for females. However new research is starting to come out that in some species that are temperature dependent sexual determination that one sex can be either XY/XX and the other one just XX.

Disclaimer, genetic work I have conducted in the past doesn't include sexual work due to sexing done due to morphological characters. This will be the case for a lot of species.

Best thing to do is try ask around any University that do work on the species in question and whether they have done any genetic work to ask this question. If you can say which species I may be able to help.



Just an extension to this, it may be possible for this to happen but will depend on the species and the age of individual. But also how experienced the operator is on tortoises.

Cheers,
TM
__________________
Fraser Gilchrist
Save Our Sungazers Campaign
www.saveoursungazers.com www.smauggiganteus.com
-----------------------------------------------------------
European Studbook Foundation
www.studbooks.eu
UK Coordinator & Studbook keeper for the Smaug giganteus & Ouroborus cataphractus

CAVEAT: any opinions expressed are my own and based on my own experiences and observations - whether you agree or disagree with them is up to you!!

IMPORTANT: if the health of your animal is giving you cause for concern, absolutely seek a second opinion from fellow forum members - your first opinion however should be that of a suitably qualified veterinarian!!

EXPECTED 2020: SNAKES: Angolan, Sumatran and Royal Pythons
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