# Temperature sex determination



## Anyfoot (Feb 17, 2016)

Hi all. 

Few questions on Temperature Sex Determination. (TSD)

Are all species of tortoises TSD?

I believe the Redfoot is, 82f- = Male. 86f = mixed sex. 90f+ = female. Is this correct?

Does anyone know if/what Homeana TSD is?

Can anyone give me examples of definite TSD for any species? 

How accurate is TSD and at what stage of egg development is this decided? ( I read middle 3rd of cycle !!!!)

Thanks

Craig


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## DPtortiose (Feb 20, 2016)

Since you've yet to get a reply:

1) As far as I'm aware all tortoises are all TSD. Atleast I couldn't find a scource claiming a species is GSD. There could very well be, Bearded dragons where always presumed to be completly GSD, which turned out to not be completly correct.

2) Haven't got a clue, you'd have to ask a good redfoot breeder

3) I'm not sure what you mean with 'Homeana', do you perhaps mean homologous?

4) There are loads of species who use TSD hormones. Crocodilains and Tuataras are for example rather well documented cases of TSD. Or are you more looking for an example how TSD works?

5) There was research done when eggs would be sentive for temprature shift, you can read the summary here: http://onlinelibrary.wiley.com/doi/...maintenance.++Apologies+for+the+inconvenience.

No clue if this ranges between species though, I would assume so.


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## Anyfoot (Feb 20, 2016)

DPtortiose said:


> Since you've yet to get a reply:
> 
> 1) As far as I'm aware all tortoises are all TSD. Atleast I couldn't find a scource claiming a species is GSD. There could very well be, Bearded dragons where always presumed to be completly GSD, which turned out to not be completly correct.
> 
> ...


Thank you.

Homes hingeback Tortoise aka Homeana.

I was hoping for examples of temps that give the desired sex for any species. I should have explained better. 

Thanks again. I'll read that link later.


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## DPtortiose (Feb 20, 2016)

Ah, scientific names are binomial though, a species is always referred to by two names. The name of the genus, then the name of the species; _Kinixys homeana_ for example.

We frankly don't know the correct temperatures for most species. We don't even know the thresholds temps for good amount of species that are bred regularly to be honest. Partially because most offspring is sold off, partially because TSD is all about ratio's. You don't get a guarantee that the offspring is a certain sex, only a better chance at most. So you need a massive amount of data that takes years to collect.


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## hingeback (Feb 23, 2016)

I also wish to know the temps. Most homeana sources I've seen only shows the incubation temps for them to hatch but not specific temps for male and female. Really hope your Rf and home's eggs will hatch this round.


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## Tom (Feb 23, 2016)

The only species that has been studied, and therefore has known documented temps is the sulcata. Generalities are often applied to other species, but it doesn't always work.

Couple that with the fact that very few people have lab grade accuracy and consistency in their incubators, and the waters become further muddied.

Now, many breeders are experimenting with day to night temperature differentials and seasonal differentials, and well, there is so much more to learn...


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## Tom (Feb 23, 2016)

Tom said:


> The only species that has been studied, and therefore has known documented temps is the sulcata. Many thanks to Mr. Richard Fife for making that happen. Generalities are often applied to other species, but it doesn't always work.
> 
> Couple that with the fact that very few people have lab grade accuracy and consistency in their incubators, and the waters become further muddied.
> 
> Now, many breeders are experimenting with day to night temperature differentials and seasonal differentials, and well, there is so much more to learn...


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## Anyfoot (Feb 23, 2016)

Tom said:


> The only species that has been studied, and therefore has known documented temps is the sulcata. Generalities are often applied to other species, but it doesn't always work.
> 
> Couple that with the fact that very few people have lab grade accuracy and consistency in their incubators, and the waters become further muddied.
> 
> Now, many breeders are experimenting with day to night temperature differentials and seasonal differentials, and well, there is so much more to learn...


 Tom, can you answer me this please. 
I put my homeana hingeback eggs in for diapause. They are at 25°c. They have chalked up. 

Is the chalking a sign of the egg developing, or is it just a sign they could be fertile? 

I am tempted to leave them at 25°c and just see what happens. 
I was concerned if they developed at 25°c they would all be male, it seems there is very little known with this species.


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## Tom (Feb 23, 2016)

Anyfoot said:


> Tom, can you answer me this please.
> I put my homeana hingeback eggs in for diapause. They are at 25°c. They have chalked up.
> 
> Is the chalking a sign of the egg developing, or is it just a sign they could be fertile?
> ...



I know almost nothing about hingebacks, and less about their eggs and incubation.

Usually, in other species, chalking is a good sign that eggs are fertile.


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## Anyfoot (Feb 23, 2016)

Tom said:


> I know almost nothing about hingebacks, and less about their eggs and incubation.
> 
> Usually, in other species, chalking is a good sign that eggs are fertile.


 I'm going to leave them at 25°c. I'm assuming the fact they have chalked at that temp means they could go on and fully develope at that same temp. We will see.


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## Tom (Feb 23, 2016)

Anyfoot said:


> I'm going to leave them at 25°c. I'm assuming the fact they have chalked at that temp means they could go on and fully develope at that same temp. We will see.



Let us know what happens!


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