Incubation temperatures and gender

[egyptiandan64]

Yes Ed different species do have different threshold temperatures, that why I just said Hermanns and Greeks, because I knew their threshold temperature.
I do believe there was a limited study of marginated and the temperature was about the same. I know they have found out the threshold temperature for Desert tortoises, don't remeber that off the top of my head. There is a study on Pancake tortoises that I recall and the threshold was I think 30C. They haven't determined the threshold temperature in most species of tortoise though.
Some species can't get to hot, like Kinixys erosa and homeana, temperatures above 84F will kill the embryo. Darren has said above 29.5C for redfoots causes to many problems and dead in shell babies.
Some tortoise eggs go through diapause, Spider, Flat tail, Pancake and Chaco always do. Leopards and Radiateds can if conditions aren't favorable for hatching.
Just to name a few things that eggs do.

Danny

[EJ]

ya got me trumped, Danny... not really.

How do you know the threshhold is not variable among individuals?

You really gotta watch the diffinitives.

Originally Posted by egyptiandan64

Yes Ed different species do have different threshold temperatures, that why I just said Hermanns and Greeks, because I knew their threshold temperature.
I do believe there was a limited study of marginated and the temperature was about the same. I know they have found out the threshold temperature for Desert tortoises, don't remeber that off the top of my head. There is a study on Pancake tortoises that I recall and the threshold was I think 30C. They haven't determined the threshold temperature in most species of tortoise though.
Some species can't get to hot, like Kinixys erosa and homeana, temperatures above 84F will kill the embryo. Darren has said above 29.5C for redfoots causes to many problems and dead in shell babies.
Some tortoise eggs go through diapause, Spider, Flat tail, Pancake and Chaco always do. Leopards and Radiateds can if conditions aren't favorable for hatching.
Just to name a few things that eggs do.

Danny

[egyptiandan64]

I do believe they were using different females in the Hermanns study, but by all means do a study and find out for us Ed. :P

I wouldn't think of trying to trump you Ed I know better

Danny

[EJ]

I'll be nice and leave out what I'd like to say... but I know you can imagine.

The point is that the eggs were grouped together as a whole... all the data was combined regardless of that factor... not important here but you know it is important as a whole.

Danny, I beg to differ on the last point.

Originally Posted by egyptiandan64

I do believe they were using different females in the Hermanns study, but by all means do a study and find out for us Ed. :P

I wouldn't think of trying to trump you Ed I know better

Danny

[egyptiandan64]

I'm just wondering why the individual is more important than the species.

Danny

[EJ]

Are you baiting me?

If we are talking in the global sense... it's not.

I don't think one is more important than another. My point suggests that there are individual differences based on genetics or whatever factor.

In the case of humans... the human gestation period is... you really didn't think I knew that... whatever... How many babies are born on the predicted date? Knowing biology I woudn't think too many.

In this case... TSD in tortoises... you incubate a clutch of egges at... what was it... 31.5c... will you guarentee a 50/50 split if you have 6 eggs? I can't remember the number of times I have this conversation in Daytona. Seriously... I thought of that as I was typing this. It comes out as an average. That's my point.

Why is this important? You incubate a clutch of eggs at... ok... above the crossover. Are they all females? Not.

You might not get it and some might not get it but it is an important point... in my opinion.

Originally Posted by egyptiandan64

I'm just wondering why the individual is more important than the species.

Danny

[wildlifewarrior]

don't wanna hijack this or anything as this is kinda the same topic (sorry to interupt your dissucssion ed) i was just wondering do you ever get hot females in tortoises. i have had them a few times in the past with my lizards when incubators have been abit dodgey and the weather has been bad, of course i keep any hot females as there too aggeresive to sell as pets. never heard of them in torts tho.

cheers

[egyptiandan64]

I do understand your point about it being an average, the 50/50 split. I do understand that the larger the group of eggs you do the closer your going to get to the 50/50 split. I do though "think" it's a step above genetic possibilities and probabilities, sex isn't the same as color.
The other thing is 95% of the people incubating eggs aren't using an accurate enough thermostat to get exactly 31.5C for the whole incubation period.
I should have elaborated on my post that 31.5C is the threshold for Hermanns and Greeks (individuals may vary), above this you will get more females than males, below this you will get more males than females. I never said all females, but the Hermanns study does say that they got 100% females at 33C and 34C.
So a question, How many studies would have to be done on TSD of Hermanns tortoises for you (Ed) to feel safe in saying that 33C and 34C will get you 100% females?

Danny

[egyptiandan64]

I've never heard of it in tortoises Christian. Be interesting to contact the person that did the TSD study on Hermanns and find out if the females gotten at 33C and 34C are old enough to lay and if they are laying.

Danny

[EJ]

The way you have it stated, danny... none.

One degree C is a pretty good spread but 'precisely' 31.5 degrees C is what caught my attention.

Sorry if that got your panties in a knot but difinitives in this hobby drives me nuts... hey... it's a personal problem.

Originally Posted by egyptiandan64

I do understand your point about it being an average, the 50/50 split. I do understand that the larger the group of eggs you do the closer your going to get to the 50/50 split. I do though "think" it's a step above genetic possibilities and probabilities, sex isn't the same as color.
The other thing is 95% of the people incubating eggs aren't using an accurate enough thermostat to get exactly 31.5C for the whole incubation period.
I should have elaborated on my post that 31.5C is the threshold for Hermanns and Greeks (individuals may vary), above this you will get more females than males, below this you will get more males than females. I never said all females, but the Hermanns study does say that they got 100% females at 33C and 34C.
So a question, How many studies would have to be done on TSD of Hermanns tortoises for you (Ed) to feel safe in saying that 33C and 34C will get you 100% females?

Danny