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Turtles & Tortoises Discussion Forum This forum is for the purpose of discussing any topics concerning the turtles and tortoises of the world.

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Old 07-16-2018, 02:35 PM   #1

A few times now I have read TSF in Tortoise post...what does this stand for?
Old 07-16-2018, 04:54 PM   #2
Temperature sexed female. It means that the animal was, as an egg, incubated at a temperature that usually produces females. A TSF animal is probably female, but there is a slight chance it will turn out to be male. The opposite is TSM. temperature sexed male.
Old 07-16-2018, 05:05 PM   #3
Got it, thanks!
And temperature sexing can result in extra scutes, correct?
Old 07-16-2018, 05:14 PM   #4
I'm not sure about that as I don't breed tortoises. I have heard that extra scutes are caused by incubation issues as opposed to genetic defects. I'm mostly familiar with temperature sexing from breeding leopard geckos. In leopard geckos, it does not cause problems unless temperatures dip below 80 or exceed 90.
Old 07-19-2018, 10:45 AM   #5
As Elena explained, it is, when actually performed accurately, using temperature during incubation to shift the proportion of sexes from one extreme (such as male) to the other (such as female). There is a transition area in between and a mixed pivotal point where results move from primarily one sex to primarily another. Scute formation tends to occur in the first third (or first trimester) of incubation. Differentiation of the gonad tends to occur in the second third (or second trimester) of incubation. For tortoises, lower temperatures tend to encourage the production of androgens and male gonad development (testes) and higher temperatures tend to encourage the production of aromatase and estrogens and female gonad development (ovaries).

Scute abnormalities can occur due to multiple factors during their developmental span. Temperatures that are sustained and too high. Temperatures that are sustained and too low. Temperatures that are spiked or dipped - especially with hard fluctuations aka wildly uncontrolled swings. An underappreciated factor in this is humidity/moisture. Drops or major fluctuations in humidity or moisture can also cause aberrant scute development.

Because scute development occurs primarily in trimester one and gonadal differentiation occurs primarily in trimester two, a sustained inducer of the former is often correlated with the result of the latter. In other words, split or aberrant scutes are correlated with female hatchlings. However, they are *only* correlated and you should see from the trimester information that these really occur in two separate phases. There are plenty of males with split scutes out there. If conditions that induce split scutes in trimester one are occurring in the lower or middle temperature range and continue into trimester two, you can get a male with aberrant scutes. If they are in the higher temperature range in trimester one and lower in trimester two, you can get a male with aberrant scutes. If in a high temperature range throughout, you will be more likely to get a female with aberrant scutes.

As I mentioned earlier, accuracy is a key element of performance when trying to force the hand of TSD. What one sets the incubator at is not necessarily what the egg experiences. I have seen many instances where an honest person has set the incubator at "90" and the egg was really only experiencing a local temperature in the low 80s in a species that has a pivotal temperature of approximately 87F. One person thought she was creating TSFs and was actually creating all TSMs unbeknownst to her until I urged her to check. Likewise, and this occurs for a number of breeders who work with forest tortoise species, there are invisible convection eddies that swirl around the eggs. When you open an incubator to check things, you know the setting and you can read the surfaces (plus/minus a certain number of degrees), but you have momentarily removed tiny microcurrents of air that may swirl around particular eggs depending on the dynamics of flow within the system. These can often occur around eggs placed in corners, for example. These are nearly impossible to fully account for. I mention them because they are there and they have a tiny invisible hand in the incubation results. Some incubator setups have designs which will, by happenstance or intention, reduce the effects of this. A similar result may occur with eggs nearer to versus further from the output of a heating element for an incubator. When the convection eddies are strong enough or the proximity to a heating element or its outflow is overly high, one can hatch unrecognized TSFs in an otherwise TSM-oriented incubation environment. Many Chelonoidis, Indotestudo, and Manouria breeders have experienced this whether they have realized it or not.

Having a night drop is a wild card. It tends to promote mixed sexes. Sometimes leaning a bit female, but you cannot really rely on that. Night drops do tend to anecdotally result in a greater incidence of robust hatchlings, but the data on that are not reliable and this observation should be taken as probably true, but not definitely true.

Speaking again to accuracy, the error ranges of one's thermometers and thermocouples/probes are factors. Some are +/- 1C. In a pivotal temperature situation where one has it close to that point, that is enough to swing over from one side to the other. If so, a "mixed" sex reading may really be all one or all of the other sex and a specific sex reading can really be mixed with the error of the measuring device not being able to account for that. The tighter your equipment specifications, the more reliable your results.

I should probably round this out with at least three more subtopics.

Genetics. Some people will say there is a hereditary aspect to aberrant scutes because their babies from a parent with split scutes often throws babies with split scutes. Maybe, but more likely one or two things are going on. The first is a lack of control of all of the factors I mentioned before. Many people are plainly bad at this process in terms of being very reliable, so human error and lack of accounting for nuances in the factors listed can be involved easily enough. The second is not so much heredity of developmental errors, but inherited *susceptibility* to the environmental triggers which induce developmental errors. A lot of this is about communication between cells as they differentiate, arrange, and divide. If a particular lineage is more sensitive to these factors I mentioned such that the communication is more easily disrupted, smaller variations in the factors at play can have larger results in such a lineage while a more "average" lineage may not see the same degree of cellular communication disruption. So the split scutes themselves should not then be genetic, but the ability to be susceptible to factors which cause split scutes could indeed be genetic some of the time.

Health. Aberrant scutes, in and of themselves, are not of negative consequence to health. Sellers will claim this often and it is indeed the truth. However, what you should keep in mind is that those scute malformations are only what your eyes detect. The same factors that can impact superficial tissue formation can sometimes affect deeper tissue formation. A digestive tract or an airway may not form properly or be complete. A gonad or kidney may have issues. That should not put you off from buying animals with funky external scutes. It is simply to say that the same players that can jack up one thing can jack up another thing sight unseen. You can have externally crazy-looking stuff that is internally perfect and externally flawless stuff that is a mess within. But if you see something funky on the outside and there was an extreme incubation period or event, that period of error-prone growth could have led to error-prone growth elsewhere in the body. It does not scare me off from buying animals with aberrant scutes at all, so my lack of excessive concern should imply something calming to the average buyer if I am considered an "investment" buyer or keeper at times. Incubating at the bleeding edge of high or the bleeding edge of low (but especially high) comes with an increased risk of mortality and sometimes morbidity as well. When you are really incubating on a hard line, developmental error frequency goes up. Just keep that in mind, but do not let it excessively dissuade you from a selection you want to make if evaluating animals you might want to keep.

Truth in labeling. This is unfortunately something that needs saying. Some sellers will call unsexed or mixed sex animals TSFs even when they know otherwise. They do it to lubricate their sales. They do it to tell the buyer whatever the buyer wants to hear/read. They want your money and an inconvenient bit of truth will not be allowed to get in the way of obtaining it if they can help it. I have had people tell me that GSD (genetically sexed) species of aquatic turtle were TSFs. I have had people tell me a tortoise whose species has a pivotal point of 87F is "evenly mixed for both sexes" at 85F (mostly male) or would try to pass off an animal incubated at 82F (which they do not know that I know) as a so-called TSF (a virtually guaranteed male at 82 for the species). A partner of mine has sold a group of unsexed animals to a retailer and that retailer then went on to declare in ads that they were TSFs. I have known a person that breeds regular sulcatas with unsexed incubation temps and had no way of producing het for ivory sulcatas, but he sold them to others, including resellers, as 100% het for ivory *and* TSFs to boot (two lies for the price of one - what a deal). On the other hand, there are those who are truthful to the best of their knowledge when selling TSFs and a lot of honest guys will plainly say unsexed when they do not know or will say TSM or TSF when they do know. There are also "good faith" labels and that is kind of a grey area. Say a guy buys from a guy. The source says they are TSFs and the guy buying from that guy calls them TSFs when he decides to resell some of them. That is what I would call a good faith label. He does not know for sure, but he is operating under the belief in the veracity of what he was told. I can understand that. I take it with a grain of salt if I am the buyer, but it was not a guarantee to begin with anyway. Another good faith label is a "probable female" or a "probable male" animal. It means one does not know as an absolute fact, but a leaning in one direction or another is currently there based on personal experience and the current external morphological hints. That can change and often does, but it is a label with an educated guess at the time (and not usually guaranteed). On the other hand, a good faith label of morph hets is risky. You are potentially on the hook for selling a het if it ends up a functionally "disproven" non-het even if you resell it on good faith. An important element for that as a buyer and as a seller is maintaining the chain of custody and being able to deliver that information and receive that information. It is also great if that can be tracked back and verified by any members of that chain of custody.

I hope this was thorough. A lot of my observations went into it.
Old 07-19-2018, 02:13 PM   #6
Thanks for the response Nickolas! More than I was expecting, but really appreciate the response. This was very helpful and educational as well.
Old 07-19-2018, 09:41 PM   #7
That was a great explanation of the process, thanks.

Makes me ask, though, given that accurate sexing is very desirable, and that air currents make it obviously difficult to maintain, why don't people incubate the eggs buried in heated sand (or other substrate) as tortoise eggs would naturally occur? Wouldn't that keep the temperature more stable and therefore reliable?
Old 07-19-2018, 10:13 PM   #8
Tradition. Burying them does help. I think many people simply like to be able to see them.

A box within the incubator to slow and more evenly distribute the flow of heat in the area the eggs are positioned can also help. It still can trap heat if there are prolonged overshoots, but not as badly affecting individual eggs and overshoots can be managed with well-arranged equipment. There are merits and demerits to this. The way the incubator is designed and these other things, including burying them, can help significantly. People do that. Some people.

An open setup is the least stable, but is frequently used. Reliable temp-sexing is most beneficial to the buyer, but not always to all sellers. If incubating for one's own collection, it is again valuable. I know in my case that if I want to "guarantee" to myself that eggs I am incubating as future breeders will be the sex(es) I want them to be, I accept that I will suffer losses and I ride the line kind of closely. That is not the case when selling, so I do not go at it as extremely nor do I guarantee the result. I could back off more when incubating my own eggs for specific sexes, but then I would have to wait one to two years to find out whether or not it worked or not. That is a long time to lose ground on and more ground would then be lost through corrective actions. So 1-2 years + 1-2 years plus + the time for incubation itself and a lot of animals being grown out instead of 1-2 years and growing out a limited number of animals while accepting the possibility of greater losses during incubation. Workload is a factor for me for that. I do not want to have to do something for 2-4 years to get the result I want when I can get the result I want in 1-2 years. Especially with fewer animals. I find it much easier to focus my attention closely on a few animals than just shooting for volume. The volume also drives me to feel overwhelmed if too high. All lost time sets other things (like selective breeding) back more and more. It is a matter of two strategies. I have seen so many guys needing females and trying to be gentle with things. Years later, they have a bunch of males and that time does not get returned. It happens when needing males, too, but that is rarely as much of a problem for most tortoise projects. I see males being flooded into the market more than I see females flooded into the market.
Old 07-19-2018, 10:46 PM   #9
Makes sense. Thanks!

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