# Incubated for...



## Kapidolo Farms (Dec 19, 2018)

[PDF] mdsoar.org
*Effects of incubation conditions on sex determination, hatching success, and growth of hatchling desert tortoises, Gopherus agassizii*
JR Spotila, LC Zimmerman, CA Binckley… - Herpetological …, 1994 - JSTOR
… There was little mortality *at* intermediate *temperatures* … E is *egg* mass. *eggs*. None of the *eggs*
*incubated* under cool (26.0 C), wet (4.0% *soil* moisture) con- ditions *in* 1991 hatched … Ap- parently
35.3 C is too high a *temperature* *for* normal development of desert *tortoise* *eggs* …

I am constantly amused by posts of chelonians for sale with the sentence "incubated for females, but no guarantee".

It's a sliding scale, not an absolute switch. 

To be less abusive with copy-write I am only including the page with a tell-all figure. 

Another reason to hold back and grow-out some of your hatchlings.


----------



## Tim Carlisle (Dec 19, 2018)

Curious (and I have not read the pdf yet)... is it really possible to sex-out the tortoises based on varying incubation methods?


----------



## wccmog10 (Dec 19, 2018)

Funny you should post this- One of the authors of this paper was my faculty advisor. He published several papers about incubation temperatures... I’m supposed to be finding some of them for the other thread about nest temperatures. 



Mizcreant said:


> Curious (and I have not read the pdf yet)... is it really possible to sex-out the tortoises based on varying incubation methods?



Lots of reptiles- but not all- have what is called TSD (temperature dependent sex determination). Deferent groups work in different ways- lizards have males at higher temps, turtles have females at higher temps (that is the simplified version of explaining it). It’s usually the 2nd quarter or middle third of incubation when the sex is determined. And like @Will mentioned- there is not a cutoff where everything above a certain temperature is one sex and below is another sex. It is a continuum. The “pivotal” temperature is where the sex ratio is 50:50. And of course- different populations can have different pivotal temperatures, and even different individuals within a population can have different pivotal temperatures. Which is why it is important to randomly assign eggs to each of your study groups. 

When you are buying a “temp sexed animal” what you are doing is hedging your bets. There is an increased chance of having a female tortoise if it was incubated at a higher temperature. But it is by no means a garuntee- unless the breeder has held back numerous babies and either surgically sexed them laparoscopically or raised them to maturity to know how the eggs of that female turn out at certain temperatures.


----------



## wccmog10 (Dec 19, 2018)

Here is another paper that seems to be talking about a certain local of olive ridley sea turtles with a higher pivotal temperature than other areas. I am just reading from my phone- so it was just a cursory glance. 

https://www.researchgate.net/profil...ys-olivacea-from-Playa-Nancite-Costa-Rica.pdf


----------



## Tim Carlisle (Dec 20, 2018)

wccmog10 said:


> Funny you should post this- One of the authors of this paper was my faculty advisor. He published several papers about incubation temperatures... I’m supposed to be finding some of them for the other thread about nest temperatures.
> 
> 
> 
> ...


Interesting. Appreciate the explaination!


----------



## Kapidolo Farms (Dec 20, 2018)

LIKE!



wccmog10 said:


> Funny you should post this- One of the authors of this paper was my faculty advisor. He published several papers about incubation temperatures... I’m supposed to be finding some of them for the other thread about nest temperatures.
> 
> 
> 
> ...


----------



## Kapidolo Farms (Dec 20, 2018)

You can only work with 'statistical likelihood'.



Mizcreant said:


> Curious (and I have not read the pdf yet)... is it really possible to sex-out the tortoises based on varying incubation methods?


----------



## Tim Carlisle (Dec 20, 2018)

Will said:


> You can only work with 'statistical likelihood'.


For some odd reason, this fascinates the hell out of me. Gonna check out those articles this weekend when I have some quiet time to concentrate on them.


----------



## surfergirl (Dec 23, 2018)

I have proof of it not being dependable. Lots of breeders try to slide the scale towards female but many times it is still nature's course to change the outcome. I did not care really as I do not breed tortoises. There are good reasons to try to get more females if breeding stock and group enclosures is what is more attractive to keepers.
Hopefully one day we can figure it out so that we do not end up with a bunch of homeless males and can breed for the most ideal sex ratio outcome. Only producing males when they are in demand.


----------



## Tom (Dec 23, 2018)

Thank you for this thread Will.

I've not been amused by this practice though. Its either disingenuous or willfully ignorant when sellers engage in this practice, neither of which are amusing to me.


----------

