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What is the relationship btwn incubation temperatures and the sex of hatchlings? I read a long time ago that the sex of baby turtles, alligators and other reptiles is determined by the temperature the eggs are kept. so how does this relate to Colubrids? has any research been done on this... the reason i ask is because of the sex ratios we see in Kings and Milks... some may produce an entire clutch of females or males, or high male low female or hi female low male while others have an even distribution so why is that??

Exert i just found:
Although the exact mechanism by which temperature determines sex is not
known, it appears that temperature determines whether the embryo develops
testes (becomes male) or ovaries (female). Early embryos have indifferent
gonads capable of becoming either testes or overies. In many turtle
species, higher incubation temperatures turn the early gonads into ovaries,
resulting in females, while lower temperatures turn the gonad into testes,
resulting in males. The reverse is true in alligators, where higher
temperatures yield males and lower, females. In mammals, the same process
occurs, but is regulated by genes rather than temperature: a particular
gene called the testis determination factor on the Y chromosome transforms
the early gonads into testes in males. Females, with 2 X chromosomes,
don't have the gene so ovaries develop.

Source: An Introduction to Behavioral Endocrinology, by R. J. Nelson
(2000) pp. 122-124

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Thanx
Royal Blue Reptilez

~ZF

Good question Zenny. I don't have an answer however.

This year I produced almost all males in my cltches. What I did different was cool the males and females to a lower temp (40F) and then heated them up in mid Feb. until the hooked up in april. Heating the males or cooling the females may have effected the sex ration outcome. I have never had all clucthes be all male or almost all male before. So something must have happened.

That if incubated as certain temps That you can dictate what sex will be the most numerous. It was like at the warmer temps would be all males and at cooler temps they would be all females. Just what I remember from when I had a couple of colonies of leopards.
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..or at least qualify it a bit..
(Speaking of colubrid snakes here)
Is the temperature at a certain time during incubation a deciding factor??
I would assume yes, but I have no clue really.
During the say..60 days it takes to incubate some colubrid eggs, would a "spike" in temps at the first/mid/last 20 days for a set duration have an effect??
I think some would think a prolonged "spike" in temps generally has a negative (early hatch, kinks, etc) but what about a shorter one? And is it more/less a difference at a certain time during the incubation period?
I wonder if most deformed (visually) snakes are one sex or the other.
Obviously, there is a lot to be discovered and I for one have let opportunities go by when things like this have happened to me by not documenting much more info.
I really have only questions...
I would also assume (possibly quite erroneously) that snakes tend to nest and lay in spots where temps do not fluctuate wildly or stay too hot or cold either for extended periods.(FR??)
In a long, hot, dry year are there more of one sex hatching?? I have a feeling there are not but it's just a feeling.
In my experience, I have had both high male to female ratios in some clutches and nearly equal ratios in others just about every year. All incubated at the same conditions.
I'd like to see someone do an in depth study on all this.
It'd be interesting.

I have had my share of kinked babies but I never sexed them. I normally feed them off to some lucky eastern and move on. I have been to stupid to look into it any further. Man I felt like you just hit me when you said that. Aside from when I have known the problem or had a real good idea of what I thought it was I never have had many kinked babies. My temps got too high in 03 and I have a eastern that probably ate $500 or more of kinked babies that I never really looked at. Aside from that and this year most other years have been really good to me.

One of you guys has to have records of the sex of kinked babies. If you do please post it. I am not expecting all males or anything but I wonder if looked at on a large scale if there is more of one than the other. I know I have had both males and females but I don't know how many of each. It would take a pretty overwhelming number of one over the other with a large number of snakes but it would be interesting.

Thanks for the thought Mark

Later jason

I don't think there is any evidence that incubation temps effect sex ratios in colubrids. But what happened to me this year (90% males)may have been caused by brumation temps.

I agree non have been found but that doesn't mean there is none. It may be further hidden than we think. Brumation temps are a interesting angle. Were any of your babies kinked?? We should get a running tally next year of all deformed babies that we have as a group and their sex. Records of brumation temps and duration would likely help fill in the picture.

Later jason

Your thoughts on the brumation possibly causing it. I dont understand how brumation would have anything to do with it. In incubation the temps would be effecting the embyros whereas what would it be effecting in brumation? I can see that it could possibly effect the sperm count in the males or egg viability in females but not quiet sure how it would effect the out come of the offspring.It is something howeve I think we should all try to keep up with this upcoming year and then compare notes?
Just my thoughts.
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Your thoughts on the brumation possibly causing it. I dont understand how brumation would have anything to do with it. In incubation the temps would be effecting the embyros whereas what would it be effecting in brumation? I can see that it could possibly effect the sperm count in the males or egg viability in females but not quiet sure how it would effect the out come of the offspring.It is something howeve I think we should all try to keep

I have heard that men that have sons have lower testosterone levels than men with daughters.

I really don't know Toby. I was just saying if it is impossible to cause sex determination by incubation temps (discussed at lenghts on other forums)then maybe its brumation. As to how it effects sperm? Lets see. Well sit you in the freezing cold and then sit you in a hot sauna for a few hours and check your testosterone levels. lol!

I have heard that men that have sons have lower testosterone levels than men with more testosterone levels.

np

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Thus....Men with more hair have more hair than bald men.....
ROFLMAO !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
HAHAHAHA!

Is that due to being in the cold or being in the heat.Also was it cause thier fathers had less hair?? LOL.....J/K
Just having fun on a boring work night!!!!!!!!!
Toby
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The hair is passed down from the female gene. So male baldness comes from the mothers side.
Also men that are bald have higher testosterone levels than men with lots of hair. The reason for the receding hairlines is the increased estrogen levels that accompanies high testosterone levels.

For what it's worth, colubrid snakes have sex chromosomes. Except that the females have the unequal sized sex chromosomes (one large and one smaller) while the males have equal sized chromosomes (two large chromosomes). This is the same pattern that is found in birds and is opposite to the pattern found in mammals.

Paul Hollander