New Research project to identify sex of hatchling and young Galapagos

Markw84

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I have started a study with the Galapagos Tortoise Alliance, collaborating with Dr Boris Tezak, to see if Dr Tezak's techniques published in his paper on "Identifying Sex of Neonate Turtles with TDSD via small Blood Samples" can be used to also identify the sex of hatchling and young Galapagos tortoises.

I have been doing studies on Temperature Dependent Sex Determination (TDSD) with Burmese Stars for a few years now. Carefully monitoring and graphing the entire temperature profile of the incubation and diapause process to later compare with sex of the young produced, once sex can be determined. This means waiting about 3 years or so until you can tell the sex of a young Burmese Star. When I saw a paper published on identifying the sex of neonate turtles -


I was immediately intrigued, and sought out the lead author to discuss application to tortoises and possible future collaboration. In addition, with the Galapagos Tortoise Alliance, our work with Galapagos tortoises and forming assurance colonies brings to the forefront the issues of creating best sex distributions of tortoises for future colonies. Since Galapagos Tortoises can normally take more than a decade to reach an age where they are reliably sexable, early determination of sex is an obvious asset! Reluctant to use any invasive techniques to sex young such as endoscopy, this use of less than a drop of blood is a very attractive possible option.

We have now agreed to start a collaborative effort to study the possible early determination of sex of these gentle giants as part of the work the Galapagos Tortoise Alliance. We will be collecting and preparing blood samples from young tortoises from newly hatched to as much as 3 years old. These samples will be sent to Dr Tezak for testing for the presence of AMH. We will be looking to see if this is indeed applicable to Galapagos, and how long that presence of AMH remains as the young tortoise ages. We will also be sending samples of blood and fluid from the inside of the eggs of newly hatched Galapagos to see if differences in protein and hormones are also detectable and useful in determining sex.

Combining the results of this study along with the study we are doing on graphing incubation temperature profiles with SensorPush, we also will be more equipped to equate the results to a better determination of the pivot point for incubating Galapagos tortoises. A most valuable tool to help incubate eggs to better fit sex ratio profiles needed for the various assurance colonies.

Exciting stuff!! And... more to come.
 

zovick

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I have started a study with the Galapagos Tortoise Alliance, collaborating with Dr Boris Tezak, to see if Dr Tezak's techniques published in his paper on "Identifying Sex of Neonate Turtles with TDSD via small Blood Samples" can be used to also identify the sex of hatchling and young Galapagos tortoises.

I have been doing studies on Temperature Dependent Sex Determination (TDSD) with Burmese Stars for a few years now. Carefully monitoring and graphing the entire temperature profile of the incubation and diapause process to later compare with sex of the young produced, once sex can be determined. This means waiting about 3 years or so until you can tell the sex of a young Burmese Star. When I saw a paper published on identifying the sex of neonate turtles -


I was immediately intrigued, and sought out the lead author to discuss application to tortoises and possible future collaboration. In addition, with the Galapagos Tortoise Alliance, our work with Galapagos tortoises and forming assurance colonies brings to the forefront the issues of creating best sex distributions of tortoises for future colonies. Since Galapagos Tortoises can normally take more than a decade to reach an age where they are reliably sexable, early determination of sex is an obvious asset! Reluctant to use any invasive techniques to sex young such as endoscopy, this use of less than a drop of blood is a very attractive possible option.

We have now agreed to start a collaborative effort to study the possible early determination of sex of these gentle giants as part of the work the Galapagos Tortoise Alliance. We will be collecting and preparing blood samples from young tortoises from newly hatched to as much as 3 years old. These samples will be sent to Dr Tezak for testing for the presence of AMH. We will be looking to see if this is indeed applicable to Galapagos, and how long that presence of AMH remains as the young tortoise ages. We will also be sending samples of blood and fluid from the inside of the eggs of newly hatched Galapagos to see if differences in protein and hormones are also detectable and useful in determining sex.

Combining the results of this study along with the study we are doing on graphing incubation temperature profiles with SensorPush, we also will be more equipped to equate the results to a better determination of the pivot point for incubating Galapagos tortoises. A most valuable tool to help incubate eggs to better fit sex ratio profiles needed for the various assurance colonies.

Exciting stuff!! And... more to come.
Well, I hope this is successful. It could potentially be a great help to many breeding programs.

There was a veterinarian named Valentine Lance from San Diego back in the early 1990's who was trying to do sex determinations of tortoises via blood samples. WCS and I submitted a fairly large number of blood samples from Radiated Tortoises but the results were not very promising back then, so we did not pursue it any further.

As I recall it, Dr. Lance claimed extremely accurate results in his tests with baby sulcata and/or Desert Tortoises. He was doing the blood work first and then endoscoping or sacrificing the babies, and sexing them via their actual gonads as he interpreted them. The high accuracy he noted may have been influenced by bias or by the fact that immature tortoise gonads are very hard to identify accurately, as borne out later by the fact that the foremost chelonian endoscopist in the country will not endoscope young tortoises for gender determination until the age of 10 months.
 
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TheLastGreen

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I have started a study with the Galapagos Tortoise Alliance, collaborating with Dr Boris Tezak, to see if Dr Tezak's techniques published in his paper on "Identifying Sex of Neonate Turtles with TDSD via small Blood Samples" can be used to also identify the sex of hatchling and young Galapagos tortoises.

I have been doing studies on Temperature Dependent Sex Determination (TDSD) with Burmese Stars for a few years now. Carefully monitoring and graphing the entire temperature profile of the incubation and diapause process to later compare with sex of the young produced, once sex can be determined. This means waiting about 3 years or so until you can tell the sex of a young Burmese Star. When I saw a paper published on identifying the sex of neonate turtles -


I was immediately intrigued, and sought out the lead author to discuss application to tortoises and possible future collaboration. In addition, with the Galapagos Tortoise Alliance, our work with Galapagos tortoises and forming assurance colonies brings to the forefront the issues of creating best sex distributions of tortoises for future colonies. Since Galapagos Tortoises can normally take more than a decade to reach an age where they are reliably sexable, early determination of sex is an obvious asset! Reluctant to use any invasive techniques to sex young such as endoscopy, this use of less than a drop of blood is a very attractive possible option.

We have now agreed to start a collaborative effort to study the possible early determination of sex of these gentle giants as part of the work the Galapagos Tortoise Alliance. We will be collecting and preparing blood samples from young tortoises from newly hatched to as much as 3 years old. These samples will be sent to Dr Tezak for testing for the presence of AMH. We will be looking to see if this is indeed applicable to Galapagos, and how long that presence of AMH remains as the young tortoise ages. We will also be sending samples of blood and fluid from the inside of the eggs of newly hatched Galapagos to see if differences in protein and hormones are also detectable and useful in determining sex.

Combining the results of this study along with the study we are doing on graphing incubation temperature profiles with SensorPush, we also will be more equipped to equate the results to a better determination of the pivot point for incubating Galapagos tortoises. A most valuable tool to help incubate eggs to better fit sex ratio profiles needed for the various assurance colonies.

Exciting stuff!! And... more to come.
Great info @Markw84 ! Could the kariotype of the torts be used to identify the gender of them?
 

Markw84

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Well, I hope this is successful. It could potentially be a great help to many breeding programs.

There was a veterinarian named Valentine Lance from San Diego back in the early 1990's who was trying to do sex determinations of tortoises via blood samples. WCS and I submitted a fairly large number of blood samples from Radiated Tortoises but the results were not very promising back then, so we did not pursue it any further.

As I recall it, Dr. Lance claimed extremely accurate results in his tests with baby sulcata and/or Desert Tortoises. He was doing the blood work first and then endoscoping or sacrificing the babies, and sexing them via their actual gonads as he interpreted them. The high accuracy he noted may have been influenced by bias or by the fact that immature tortoise gonads are very hard to identify accurately, as borne out later by the fact that the foremost chelonian endoscopist in the country will not endoscope young tortoises for gender determination until the age of 10 months.
Thanks for the reply, Bill. In his work almost 30 years ago now, Dr Lance was using the presence of plasma testosterone as his marker to determine sex. This has been shown to be unreliable in young tortoises. With study the last few decades on epigenetics and the cascade of events with mRNA, proteins, and hormones that begin the process of metabolic functions, it does seem the presence of AMH is quite reliable. That is the hormone that degenerates the mullerian duct and ceases the development of female organs.
 

DoubleD1996!

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This is awesome. This could pioneer further advancements. Perhaps some kind of small machine, similar to I don't know, an acu check for diabetics. Something that size where you can stick the turtle and the blood is analyzed to determine sex.
 

Markw84

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This is awesome. This could pioneer further advancements. Perhaps some kind of small machine, similar to I don't know, an acu check for diabetics. Something that size where you can stick the turtle and the blood is analyzed to determine sex.
some of the group Dr Tezak did his original paper with are working to do that! - to try to develop an easier and portable test to use with sea turtle nest work.
 

zovick

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Thanks for the reply, Bill. In his work almost 30 years ago now, Dr Lance was using the presence of plasma testosterone as his marker to determine sex. This has been shown to be unreliable in young tortoises. With study the last few decades on epigenetics and the cascade of events with mRNA, proteins, and hormones that begin the process of metabolic functions, it does seem the presence of AMH is quite reliable. That is the hormone that degenerates the mullerian duct and ceases the development of female organs.
Thanks for the detailed explanation, Mark.

This methodology is very encouraging and could be extremely beneficial to any number of breeding programs for endangered chelonians.

Please do keep us posted with the findings as things progress.
 

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