The odds gods, statistics, and patience with hets. - FaunaClassifieds
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Genetics, Taxonomy, Hybridization General discussions about the science of genetics as well as the ever changing face of taxonomy. Issues concerning hybridization are welcome here as well.

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Old 07-22-2019, 10:29 PM   #1
nickolasanastasiou
The odds gods, statistics, and patience with hets.

As some people are aware, I have worked with some chelonian morphs for a decent number of years. One of these is the ivory (leucistic) morph of the sulcata tortoise.

In 2015, I added two juvenile/subadult het (heterozygous) for ivory females to my project from another party. I eventually transferred them to my project partner in TX since most of the land areas I have directly available to me in FL are not the best for Savannah species for one reason or another. Not terrible, but not ideal on these properties in particular. Perhaps a new property someday will change that.

For reference, we use only homozygous (visual) ivory sulcata males as our breeders. Neither male hets nor wild type (no ivory genetics involved) males are kept - much less provided access. There was no possible genetic contribution of anything other than Fife. bloodline ivory males.

Anyway, the females matured and then "seasoned" in 2016 and 2017, starting to produce bountiful fertile clutches as sulcatas tend to do. One of these females proved out in her first clutch by producing ivories as hoped. The other did not. The chance per egg, as an independent statistical event, of getting a homozygote (ivory) from ivory bred to het is 50%. The principle to understand here is that it is a coin flip each time and there is no result "owed" regardless of eggs hatching before or after any other egg. That does not mean a clutch of 20 should yield 10 ivories and 10 hets. Over a large enough sample size, it is assumed that things would even out, but my experience is that this is often not actually the case. I consider 40% of a clutch being ivory in this scenario to be pretty fortuitous and ~30% being ivory to be generally more realistic.

For the second female that failed to produce ivories, we were racking up the het baby results. We assumed after the first season that we could rule out the possibility of her being a het and we had planned to list her for sale this year as a possible het that was largely considered to be a non-het based on our results. She had given us 180 hatchlings, all hets, and then the improbable happened. An ivory emerged. We were so surprised and it was sort of extra pale in appearance compared to many of our ivories, so we disbelieved it at first or thought it might even be something spontaneously new. We track and separate all of our eggs by clutch. No mixing between females occurs when we collect eggs and incubate. There were no mistakes in identifying the source. The sires had not changed. The dams had not changed. In subsequent eggs, this female has since thrown us a few more ivories. Not nearly as many as her sister, but infrequent sprinklings here and there.

I share this firstly because it is cool. The statistical chance as a string of 50% chances 180 hatchlings strong is impressively improbable, yet it happened. I used to use a metric of 20 consecutive results in order to functionally rule out a supposed het's genuine het status unless I produced it myself (which would allow me absolute confidence in the ideal scenario). I now have to revise that metric to two full seasons of results before I can make a call in good faith on a "disproven" het (although one can never truly disprove a het by math; the chance simply infinitely approaches zero without reaching it). I share this secondly because I see people quick to jump the gun time and time again with snakes, lizards, turtles, and so on regarding hets. Do people sell and buy fake hets? Often. VERY often, in fact, and it is quite a shame. However, I see people thinking they deserve an early win going into a game of statistical chance and then taking a less fortuitous set of results with a relatively small sample size to the BOI or other settings to gripe. Your three eggs did not yield an albino with hets involved? Your seven eggs did not yield a piebald with hets involved? Your ten or twenty eggs did not yield a double visual with hets involved? These scenarios have disproven nothing regarding the legitimacy of the het label assigned to a given parent. You may have a non-het that was sold to you under false pretenses. You may also have a perfectly good het and perfectly bad luck. One's bad luck is not a justifiable reason to bash someone's reputation, so one should keep perspective on this. If you want only good luck, buy all visuals. If you want statistical chance with acceptance that not every egg will go your way while gaining affordable access to a morph, dabble in hets.

I have never heard of anyone having to wait for their 181st result to prove out a morph before. That is why I share this. It is an interesting (and uncommon) case and something to take into account when exercising patience and proving out a het.

One of the sires, two dams (including the one in question), the 181st baby, and some later babies are shown.
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Old 07-25-2019, 04:56 PM   #2
WebSlave
Yeah, the generics gods can certainly be unkind at times. Unfortunately, no one seems to be able to quantify the "luck" component of statistical odds. I always found it healthy to expect the worst, so that when the worst didn't happen, you were pleasantly surprised.
 
Old 07-27-2019, 12:30 PM   #3
nickolasanastasiou
It gives me peace of mind to always have one half of the parentage be a homozygous/visual animal. That way, as long as retention of sperm from another male is not a concern (zero chance in this case due to the history of exposure), I can say with absolute confidence what the genetics of the offspring are even if the results regarding morphs/visuals are abysmally poor. When I produce hets by myself for myself, I know I might have to keep waiting for the possibility of better results down the road and, if a customer would ever buy a het I made under the same strict parentage, any "not proving out" types of results would be due to a problem regarding the genetics of the mate, a problem of impatience (sample size), or some sort of scheme. I explain that the bet customers make is the same bet I make regarding the future of my projects since I tend to sell off the previous generation after I feel secure enough with my numbers in the next generation if a project involves refinement over generations (such as with my hypo cherryheads). Visual -> het -> visual -> repeat until satisfied and then cease the process. For the project this thread is about (ivory sulcatas), I have been satisfied for years now with the quality and so the only thing I have been working on is turning holdbacks into additional breeders until a particular target has been reached for the number of adults involved in the colony/project.

2018 ivory and 2018 het shown before I sent them to my main colony that resides in TX back in April of this year.
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Old 07-27-2019, 12:55 PM   #4
WebSlave
I have been fascinated by a simple test to help determine a "luck" quotient. Many 2 prong AC plugs these days are keyed in such a way that they will only go into a wall receptacle in one direction. Simply pick up a plug, and without looking, just try to put it into the wall socket. Even though there is a 50/50 chance you will have it correctly oriented, at least in my case, there is an 80 percent (or better) chance I will be holding it in the incorrect orientation.

It has gotten to the point that now when I pick up a plug, without bothering to look, I simply flip it around from the way I picked it up and would have tried to plug it in, to force the bad odds to work in my favor. Now I am wrong only 20 percent of the time.

But more on topic, selling hets has always been an iffy proposition, simply because it places the seller's reputation with a purchaser completely at the mercy of the luck of that purchaser. The truth of the matter is, no matter the percentages of possibilities, the actual real world results of breeding hets to hets together will produce a number of the target gene combinations anywhere from a zero percent to 100 percent POSSIBILITY for any and all of a clutch to produce what you are hoping for. Any anywhere in between. With the likely results being an even spread of both extremes when you are talking about a single clutch of offspring.

Heck, I recall MANY times breeding double hets together and then when the clutch would hatch out, I would have several babies expressing PART 1 gene, and then have several more babies expressing PART 2. But luck raised it's ugly head and refused to grant me any babies expressing BOTH of those genes. This has happened more times than I care to think about. That is why I concluded long ago that the only way to compensate for the frivolous and capricious influence of luck is by trying to overwhelm that handicap with large numbers.

As for people BUYING hets, you really need to go into this understanding what this means about your hopes and future plans of any projects you are counting on. Yeah, visuals are always more expensive. There is a reason for that.

I can remember people asking me about the genetics of some of the corn snakes I developed, and when I told them, they decided to just buy those genes saying they would save money by just rolling their own. Gave me a chuckle, it did..... I wonder now what they are thinking about their plan?
 
Old 07-27-2019, 01:28 PM   #5
nickolasanastasiou
Ha. Reminds me, in a way, of people attempt to insert male USB plugs without looking (prior to USB-C). The first time (each time) was most often fruitless for many.

Chelonian morph breeders run into that issue with the combo morphs involving multiple genes. Especially the slider guys since there are more morphs for that species than most other turtles. Lots of 1/64 types of results in a perfect world. A perfect world that not that many of us live in. Serious snake people probably know these woes better than anyone due to volume. The extra dose of pain for people breeding tortoises is the lengthier generation time typically involved. Thankfully, when it comes to growth rates, I have a bit of an advantage, but a lot of keepers do not.

I have always seen purchasing hets as more of something better suited for the statistically aware for projects which lack many options than for those with a lower willingness to part with disposable income, but it unfortunately goes the other way from what I see in general practice. People go for a worse chance trying to save a few bucks on the front end of a project that consumes years of time and plenty of care-oriented money along the way. Especially when it comes to hatchlings, getting them to become good breedable adults even before reaching the point of next-gen breeding results is a task unto itself. Then having opposite sexes. Then lucking out on stats. The things set against the beginner pursuing success this way are numerous. Over the course of years, it tends to be "cheaper" overall to shell out the extra money for visuals if they are available and the buyer's finances can be stretched far enough. While I leverage hets for my own goals within my own projects, I think visuals are the way to go for those who understand genetics and statistics the least (or for those who want things to trend in a manner slanted in their favor). Even then, for everyone, visuals of opposite sexes should provide better project justification than hets as long as there are not weird weaknesses in doing visual X visual pairings (some lizard and snake morphs have issues with visual X visual, although the majority do not have such issues). I have plenty of projects that are visual X visual simply to reduce "waste" in the form of extra hets when visuals are what the market demands most of all. Self-evident value by appearance is less of a hassled sale than one involving 1) hidden value and 2) trust between parties who do not know one another well. Reputation helps a lot, but there are still hassles with hets in some interactions.
 

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