Reptile & Amphibian Forums

Just thought I'd share in case you didn't see it in the Pituophis forum: Terry Vandeventer has repeated results demonstrating temperature-controlled sex ratios when incubating eggs of Pituophis ruthveni.

Incubation of 82 deg F: around 50/50
Incubation of 79-81 deg F: higher female ratio
Incubation of 84 deg: higher male ratio

Very interesting results, especially since they can be repeated. This just opens up the possibility of this kind of thing going on in other species.
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Mark

Amaerican alligators sex is determined by the temp the eggs are incubated at, why wouldn't it work with other reptiles?
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"Not one shred of evidence supports the notion that life is serious."
1.1 Cal Kings
0.1 Mali Uromastyx

>>Amaerican alligators sex is determined by the temp the eggs are incubated at, why wouldn't it work with other reptiles?
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I don't know why it would or wouldn't. It doesn't necessarily have to work on snakes like it does with alligators or lizards.

I believe current literature regarding snakes pretty much dispells the idea of temp-determined sex in hatchling snakes. So that is why this example is interesting. It may (or may not) open the door for observing this in other species of snakes as well.
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Mark

I beleive it does.

That may explain the Peanut Butters the first 3 years i produced them I had only male PB's and no females. Just male and female hets. I had 6 cltches per year and not a single female PB. Then in 2005 I had a female and then several female PB's in 2006. Same this year.

I had the same thing happen with the hybrids. Alsways high males. Extremely high on very single clucth. There was a lot of clcuthes I produced so the odds were very unlikly this happened by chance. The room i incubated was a large walk in closet with a door on each side. it was alway cools and my incubation times was always way over 60 days. This year I incubated in a diferent warmer part of the house and got mostly even sex ratios and ven high females for the PB"s. But I also had late clutches. about a mont behind previous years..so maybe that effectes sex? Or maybe it is a way a male or female is brumated (temps , food conditions) that can cause sex determintion. I don't know just guessing other variables that could cause sex determination besides incubation temps. Playing devils advocate here on a tangent.

This sort of thing (cool temps/longer incubation period=high male ) has been going on for years for me. But as you said it was always dispelled by the "experts" so i ignored what was happening to a fault. I just figured I had bad luck. Thats what you get for listening to "armchair scientists" (armchair are those sceintists who come up with theories and don't do things themselves, usually those with a large college education). You see a lot of that in the nutrition and suppllement industry as well. Doctors who look like crap telling you to eat this and that. LOL!
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"Yeah ya told me, and ya wrote it down too. But how the hell am I supposed to remember!"

this topic is why the pet books are good for beginners and intermediates, but if you want to really achieve specific results you have to dump the status quo, experiment and listen to your animals, as FR preaches. Even if it takes you a decade to come up with something good. Sometimes even the forums are detrimental in passing along recipies as firm natural law, but then they are also the place of some really great ideas and inspiration.
keep the wagons movin'!

daveb

There are many more reasons for a morph to be passed on throgh only one sex. Sex linked mutations are common and have their own characteristic pedigrees. I am not saying thats whats going on with your PBs, I have no idea. BUt you said yourself you got female hets, which means that you did get females from the same clutches. Even if your ratios werent 50/50, I don't think that it really supports TSD.

It works for some turtles as well, but alligators are no more reptiles than birds are. Turtles too for that matter

Vinny
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“There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone on cycling according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” -C. Darwin, 1859

Natural Selection Reptiles

Excellent point! I just include "Aves" in the Reptilia clade for my practical purposes. Archosauria belong there with the lepidosaurs and anapsids, if you ask me! As the resident genetics guru, I think you're better qualified to explain the ZW system than I. Your explanations on "how it is" are easy for the layman to understand (as evidenced in you REPTILES article).

P.S. - How are the Cosala locality sinaloans doing this season?

-Cole Grover

It's possible but I've not heard of a single snake species that has been demonstrated to be TSD when investigated with the scientific method.

That being said - my cal kings gave me exact 50/50 ratio this year (8 of each).

Incubated at 80F for most of the duration.
During the last month or so, as the summer heat increased ambient I had the incubator shut off during day so they dipped to high 70s during day.
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11.14 L. getula californiae (Cal. King)
2.3 L. getula nigrita (MBK)
1.0 L. getula floridana (Brooksi)
1.1 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
0.1 Heterodon nasicus nasicus (W Hognose)
4.2.14 Elgaria multicarinata multicarinata - (Cal. Alligator Lizard)

First let me say I have TONS of respect for Terry V.-His contributions to herpetoculture in general and P. ruthveni in particular are above reproach.

However, his observations in this instance fly in the face of every formal study on the subject for the last several decades. Every single study done previously across many families, genera, and species have all confirmed that, in snakes, sex is determined chromosomally. These reults are interesting, but a much larger sample size (in the hundreds of eggs) is needed to confirm. Even then, there are other possible explanations-for example, it was suggested that higher temps lead to differential sexual mortality (female embryos tend to die during incubation at higher temps).

Given the previous history, some healthy scepticism is called for here.

Brad Chambers

n/p
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11.14 L. getula californiae (Cal. King)
2.3 L. getula nigrita (MBK)
1.0 L. getula floridana (Brooksi)
1.1 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
0.1 Heterodon nasicus nasicus (W Hognose)
4.2.14 Elgaria multicarinata multicarinata - (Cal. Alligator Lizard)

Great points.

I should have been more careful with the wording: the "works in a pituophis" was a bit bold, since nobody knows what may be causing the result.

Good discussion though, and I hope to learn something from folks here on this subject.
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Mark

Brad, do you realize how long it is going to take to get hundreds of P ruthveni eggs????????????????
daveb

So what's YOUR holdup man????
Let's go! C'mon. On your bike....
:Mark
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Surrender Dorothy!

crimsonking.piczo.com/

ha
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"Not one shred of evidence supports the notion that life is serious."
1.1 Cal Kings
0.1 Mali Uromastyx

lets see, if i leave right now and do 150 miles a day i will be there in 10 days.
one night in PA
one in MD
one in VA
one in NC
two in SC
three in GA
one in n. FL
JUST IN TIME for the good stuff Sunday afternoon...

do you think they will charge admission after 3pm on Sunday?
daveb

I think it could be tested w/o hundreds.

I think it would take several clutches - separate eggs from the same clutch into two groups, for each clutch.

Flip a coin to see which half of the clutch is incubated warm and which is incubated cool.

A few years of data should provide enough statistical certainty to make a more robust claim.

Also - it could be tried with something like pac gophers or bull snakes that are much more frequently bred and easier to obtain females for.

While demonstrating that, say, pac gophers are not TSD would not necessarily mean that ruthveni are not TSD, showing that pac gophers are TSD would add tremendous evidence towards ruthveni beiong TSD.

Some of the issues that need to be taken into consideration are the environmental conditions of the female. I believe in pits it is the female gamete that allegedly determines sex via GSD. Supposedly (memory, possibly faulty, of what my biology textbook said) when gametes are produced for diploid GSD species, you will get an equal ratio, but there may be influences that alter the ratio once produced before used for reproduction.

That's why it would be a good idea to split eggs from a clutch if possible, so that you don't end up by chance having biased females screw with your results.
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11.14 L. getula californiae (Cal. King)
2.3 L. getula nigrita (MBK)
1.0 L. getula floridana (Brooksi)
1.1 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
0.1 Heterodon nasicus nasicus (W Hognose)
4.2.14 Elgaria multicarinata multicarinata - (Cal. Alligator Lizard)

I mentioned this subject not too long ago on another forum. Most everyone told me I full of it.

Last year I bred only cobras. Black & White Spitters and Sumatran Spitters. I kept my snake rooms at 85-86 degrees. I cooled my snakes, and warmed them back up to 85-86 degrees. The snakes bred at 85-86 degrees and I incubated the eggs on a shelf that stayed 85-86 degrees. I got ratios of 12.3 and 5.1.

I started keeping my snake rooms at 80-83 degrees right after those eggs hatched. So for a year, my snakes were now being kept at 80-83 degrees. I cooled my snakes, and warmed them back up to 80-83 degrees. The snakes bred at 80-83 degrees and I incubated the eggs on a shelf that stayed 80-83 degrees. This year I got ratios of 7.13 and 2.2 respectivly.

I don't think splitting up a clutch is the way to test. Whose to say sex wasn't determined by the temps when they actually bred or when the eggs were forming in the female? Why not incubate the whole clutch at one temp one year, and make the same exact breeding the next year and incubate at a different temp.

I bred the exact same pairs of snakes. At cooler temps I got more females than I did at higher temps. Splitting up the eggs does not make any sense, as they cold have already been temp sex determined before they were layed, thus you have proven nothing.

RC

It's been known for decades that most snake species have a pair of different sized chromosomes, like birds. And bird sex is determined by the chromosomes.

I'm going to have to dig up the Burger and Zappalorti paper and see what that says. And if there is a suggested mechanism.

Paul Hollander

I would appreciate any info on this subject.
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Mark

>>
>>I'm going to have to dig up the Burger and Zappalorti paper and see what that says. And if there is a suggested mechanism.
>>

If you look in the original thread in the pit forum ("fresh from the oven", I posted the paper's journal info so others can find it. I found more of their excellent work searching at scholar.google.com
daveb

i dont use an incubater and my themometer is broke but let me tell ya ,the feel of the air and the lenth of incu. 66 days in my closet w/ no artificial heat, surprized me on a clutch of corns.I was putting up and sexing the nnewborns and the FIRST ONES out of egg i popped 11 males in a row,now a few females are crawling out of the eggs,but ELEVEN in a row i mean after 6 in a row I was cursing a little.Chris

What would be required for SCIENTIFIC support. The data is already enough for me, as a breeder, to say "Well, just to be safe I'm keeping my incubation temps between 78 and 81". But formal herpetology needs a lot more data. I know I myself have had lots of colubrid clutches turn out all or almost all one sex as a random occurrence-but when you look at the same parents over several years it all evens out.

But as for Journal of Herpetology-C'mon Dave, we need those 50 P. ruthveni clutches, pronto!

Brad

I dont know what kind of sample size we are talking about but to be blunt, I do not believe this claim.

As other posters have said this flies in the face of SOOOOO much research and evidence. THis is not one of those areas where you can say, "oh it just hasn't been studied enough". It has. Do you know how many people have bred how many millions of colubrids in the past 40 years? How many people have even made their living off of it? And don't you think that since nearly all turtles, crocodillians, and some geckos are temperature sex dependent (TSD) that these people might have been curious about it?

Sex determination in snakes is chromosomal, just like in people. Well not just like in people... in people males have two chromosomes that don't match XY while females are homogametic XX. In snakes its the reverse, the males are XX or (I think maybe they call it ZZ) and the females have mismatched chromosomes. These are easy phenomena to check with modern imaging techniques you can litterally see the chromosomes, we are not talking about terribly mysterious science.

If other peoples larger scale research wasn't enough, I personally have incubated snakes at all kinds of different temps and gotten totally random results, trust me I have looked for patterns. I have gotten entire clutches of males and entire clutches of females from every temperature.

Like I said I don't know anything about this claim but I am more than skeptical. I checked the pit forum and didn't see a post, but I would love some more information.

Remember how all of those snake books for all of those years told about sexually-mature male combat "dance" in rattlesnakes, and now we know that it can occur in rattlesnakes of all ages, mature or not, males and females, and it is not just about mating? How could have all those experts have gotten it incorrect for so many years? Actually, some hobbiests figured it out some time ago but risked being made to look like idiots if they challenged the norm.

If I told you that there is a breeder who uses a slightly altered incubation temp for tricolor king eggs and gets proportionally brighter orange-red offspring that way, would you believe it? It is true. Any research to support that? Probably not.

Point is, I think we should value the hobbiests' experiences and data. It may not prove (TSD) or disprove something one way or another, but it can be a clue to better understanding as a whole. True, my wording that TSD works in P. ruthveni was not a good way to segue into the subject, because I have no clue about the biology of reproduction in snakes at that level. Bad claim by me, but still very interesting data by the breeder.
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Mark

Mark-
No science ever gives us the ultimate truth. Science just gives us the best answer at the time. Most results become theorys. But eventually, if enough people achieve the same results without finding any exceptions, the theory becomes essentially fact.

Sure people make mistakes and draw incorrect conclusions all the time. But the amount of people studying crotalus combat behavior is nothing compared to the number of people breeding colubrids.

I agree with you that regardless of why, these are fascinating results. However I think that TSD is a big leap. I would still like to learn more about the specific situation. Where did you here about this?