Reptile & Amphibian Forums

Here is my secret weapon male bowtie Thayeri with a couple of his ladies. He has bred many females and his offspring have all carried his pattern (some stronger than others), as well as his patternless underside. Even when he's bred females with strong milksnake patterns all the babies come out with extreme leonis or bowtie patterns. Next year I will breed him to one of his daughters who looks just like him. Super Bowties? Hmmm...I doubt it since this looks like a dominant gene. But I bet they will be very cool!

This female is in the process of laying right now. It looks like she will have nine good eggs and three slugs this year:

Here he is with a vermilya female. She is small, but she laid a whopping eighteen eggs this year! Twelve of them look fertile...

The first female referred to in the text of above post...

The second female referred to in the text of above post...

I don't think incest is best for any kinds of animals lol in people it can cause some real miss haps. I would not want to end up with some deformed snake babies that may die on me.

the reason inbreeding is to be avoided is because IF there is any HIDDEN genetic flaw (an example in humans would be cystic fibrosis, a disease inherited as a simple recessive) the chances of BOTH parents having that gene is heightened because they're related and would have had a better chance of having inherited the same gene.

Back to the CF example: various people moving through the general human population carry the CF gene. If they happen to reproduce with someone who also carries the gene, then one-fourth of their children would be afflicted with CF, just as one-fourth of babies from a het/albino chain king pair would be homozygous for albinism, or would "show" or manifest the albinism. Obviously the chance of a king being het/albinism is greater if it comes from a line that ever had that gene in it, and breeding (inbreeding) kings from such a line (two "possible hets" would be more likely to produce albinos than would a breeding of two unrelated kings from the general population.

So breeding related animals (inbreeding) is both more likely to produce babies showing a DESIRED trait and more likely to produce babies showing any UNdesired, HIDDEN trait. To the extent that characteristics like feeding response, fecundity, even longevity are inheritable, then inbreeding ("incest" can capitalize on those traits, while conversely exposing the offspring to the consequences of any hidden and undesirable traits (poor feeding response, poor fecundity, etc.)

Sorry this is so long. The point is we're best served in evaluating our animals and our breeding strategies if we understand the logic behind some of the prohibitions that are sometimes bandied about.

I'd welcome more scientific explanations (or corrections) on these issues from others on the forum.

peace
terry

Very good understanding. We humans carry on average about 4 lethal recessive Mendelian traits that are sometimes totally unique to us. Because the chance of meeting someone with similar lethal trait is perhaps billions to one, we never see these recessives paired to exhibit the trait.
These extremely rare recessive lethals can pair up and express when human family members(brother-sister, father-daughter) interbreed. THis can be seen using the Punnett(sp?) squares you alluded to Terry.
You can perhaps find somewhere on the internet, the trace of hemophila within English royal family, originated with a mutation arising with certain king or queen and was passed down.
These recessive lethals are pretty much a result of the genetic damage we accumulate from the environment.
Hope this helps.
Matt

...But no-one has addressed what matters to us as herpetoculturists; namely, how many generations can you breed brother to sister, and so on and so on, before deleterious effects become noticeable?
I know that there are some effects of in-breeding in snakes, such as split bellies, varying degrees of eyelessness, abnormalities of scalation, etc. How many generations of in-breeding would be necessary for abnormalities to become manifested?

Simon

To make sure were on the same page for the discussion lets talk about albinism.
Use albinism as an example. In nature albinos are very rare. In nature, albinism can be considered a recessive lethal allele. This is because in nature the animal is a glowing target. The heterozygotes can live fine carrying the gene but not expressing it. Heterozygotes can pass the allele or gene as well. This is fine and dandy for the population as a whole because albinism is an extremely rare allele to come across in nature and thus the poor animals that get both recessives and express it get killed.
Because humans usually have better medical and family records than snakes, and because of recent genetic studies, we know that humans carry abot four exremely rare lethal alleles per individual. These are so rare that the only way for them to pair up realistically is with a intra-family mating. For reptiles the case isn't known exactly but the same forces that cause these genetic defects are alive and well with all animals. It is important to concentrate on the principle, not the exact figures

Lets say your carrying four lethal recessive traits, never before known to humanity, but these traits arose from genetic damage to parents or grandparents.
Your society promotes brother-sister marriages, you produce children with your sister.
Here's the math.
You have a 1/2 chance of inheriting each recessive lethal from parents(say either parent does not have same mutation)
So the probability of you becoming a carrier for any of the four recessive lethals is 4X(1/2).
Therefore you are probably going to be a carrier for at least two recessive lethal traits. These of course affect you in no way because you are simply a carrier.
Sister, though has the same probability of being a carrier, on average two traits, though like you she can carry between 0 and 4 traits. You may need to break out the Punnet squares to follow the example.
Now, the probability of you carrying the same trait as your sister is (2/4)X(2/4)=4/16=1/4.
Remember that you this is the probability of you both being carriers of the same trait that isafter a first generation brother-sister mating for a trait that is so rare it has never occurred before in nature.
Lets say you have four offsring and you both carry the same recessive lethal trait. Lets stick with one shared trait to make it easy.
Each child has 1/2X1/2 probability of getting each allele(gene)so that 1/4 kids do not carry gene, 2/4 kids carry gene, 1/4 kids get both recessive copies and thus demonstrate recessive lethal condition(examples in humans-cystic fibrosis, Tay-Sachs disease, Sickle cell anemia, or mabe something so horrendous you never see it because fetus never makes it to birth.
So basically, there is a 1/4 chance of a child receiving a full-dose recessive lethal condition of a trait that is so rare it has nver been seen by the world. that is through one brother-sister mating.
Don't have time to go through the math but a child-parent mating has a double the chance of producing an offspring with the condition.
Keep in mind the lethal does not have to mean it is obvious.Also, for real world discussion many traits that can occur unnaturaly through brother-sister matings may just cause harm. It may just be an inability to process some enzyme in the liver which allows the animal to live but not a full life and its a life with complications. Also, deletrious traits don't have to be lethal they may just be compromising to the animal. It may just be an inability to process some enzyme in the liver which allows the animal to live but not a full life and with complications.

One would say at this point, that's silly, do you know how many inbred snakes there are out there? True, keep in mind though an animal can be compromised yet still survive, particularly in captive conditions. Most frequent report I hear is with regurgitation of snakes that have been bred back to each other.
Also, keep in mind that we have liittle information on what is happening with snakes because they rarely show symptoms. A snake can have sickle-cell anemia but never express the anemic conditions because they sit around in a tub or tank all day.

Also, some lethals can result in still-births or abortions so that may be why they are not reported. Very few people really care anyway. They consider the animal just fun anbd pretty and for some the breeding is a business.
Personally, I appreciate the animal and what make it tick. I do not want that compromised, if only for aesthetic reasons. I like to think that if a hit occurred to a wild population, that my animals could be good representatives of the species without magnification of deletrious traits that occurs through inbreeding.
Some of this may not be clear to you, If it is not i am sorry but it takes a long time to explain through writing(instead of tables and equations)
Matt

Matt,
I was actually able to follow all of that, LOL! It was very well written, and it made perfect sense to me.

Thanks.

Simon

Thank God you understood it. Glad you liked it. Thanks for letting me know it wasn't a waste of typing.
Matt

I was wondering... Since snakes have been evolving and evolved for such an astronomically longer time than mammals. I would think that snakes and reptiles would have a "cleaner" genetic pool. Ii don't know if this is logical or not, but it makes sense tome.

Okay, I'm a high school math teacher, AND I have a degree in statistics. My husband is a high school science teacher and has a degree in genetics. I just CAN'T let some of your argument go without challenging it, and I couldn't read the rest beyond this following quoted paragraph, just because I couldn't let this fallacious argument go. Correct me if I have misinterpreted your statement

you said:

Lets say your carrying four lethal recessive traits, never before known to humanity, but these traits arose from genetic damage to parents or grandparents.
Your society promotes brother-sister marriages, you produce children with your sister.
Here's the math.
You have a 1/2 chance of inheriting each recessive lethal from parents(say either parent does not have same mutation)
So the probability of you becoming a carrier for any of the four recessive lethals is 4X(1/2).
Therefore you are probably going to be a carrier for at least two recessive lethal traits.

Okay, first of all, if you multiply four times one half you get two.... in statistical terms that means 200%, which is impossible. There's no such thing as saying that a person has a 200% chance of inheriting a specific gene.

If a person (or a snake) has four recessive lethal genes. then the probability that he or she will pass on any ONE of those genes to a single offspring is 1/2. The odds that a person will get TWO of those genes is 1/2 times 1/2 which is 1/4. The odds that a person would inherit all four of the lethal recessives is 1/2 raised to the fourth power, which is one in sixteen odds.

Now reality is NOT like statistics, when your talking about your pet snake Bob and his "sister" Sally. They may have a statistical chance of having a particular outcome, but reality is always a little different than statistics predicts, since it is random

Take for example two litters of mice I recently had born. All the parents (half siblings) were recessive for hairlessness. One litter was three babies, and one was five. Altogether that made eight baby mice, statistically speaking I should get 1/4th of the babies as hairless, which would be two babies. And lo-and-behold, I got two hairless mice from those litters. The litter of three mice had two hairless, and the litter of five had NO hairless. Now if you looked at each litter, they are off on the odds, but if you look at both, they start to conform to the expected percentages.

I don't know if it's the same in snakes as in mice, (but I think it is), but if you breed genetically distinct critters, you start to get to inbreeding depression after three or four generations, if you can continue to breed siblings together (ie they don't become too messed up by lethal or deleterious recessives) by the eighth or ninth generation most of the deleterious genes have been bred out and the animals become close to genetically identical (I think that 97% genetically identical is the statistically accepted figure). By the time you get to the 20th generation the animals are 99.8% genetically identical.

Now if snakes have an "already inbred" population (again, this is subject to opinion, though if there is specific SCIENTIFIC research I would love to read the scientific report) this could mean that a lot of the deleterious genes might have already been bred out. This is more likely in SMALL isolated populations than in broader ranging species.

Inbreeding is definately not something to do without having a strong understanding of genes. Once an animal shows a specific deleterious gene, it is important to realize that breeding from that snake's parents or siblings causes increased risk of perpetuating such nasty genes. It just requires common sense, a knowledge of genetics, and the willingness to do the right thing if/when something bad crops up.

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~Sasheena

and the kids: Tantilla, Tantillas, Lightning, Kinkee, Maple, Castle, Bishop, Queenie, Jester, Pandora, Phantom, Aphrodite, Athena, Hermes, and Lady

Please rework your figures now that I have drawn your attention to the operating words any vs all. I never mentioned statistics, just simple probabilities.
That took me a long time to write, it was written for someone who I did not even know would have any background in math or not. Its hard to write for all audiences in one post.
Please read the operators carefully, any vs all, and please give me the consideration of reading the entire post before coming up with refutations to parts you have deduced are there but have not read. I would do the same for you. Debating is fine but please read what the other person is saying.

As i understand it. Deleterious genes will show up (and thusly can be eliminated from the line) between the F2 and F6 generations. By the eighth generation, anything that was there would have shown up. There are specific breeds of lab mice and rats that have been strictly line bred for over 70 years. These make fantastic specimens because their genetic makeup is almost identical. Their genetic similarities can be used as a constant in whatever experiment you are doing.

My understanding is that those lines do have to be rotated through with others, the genome being similar, not identical for certain strains.
Yes I have heard of problems arising with some of the strains because of inbreeding depression. Even then, for experimental reasons what really matters is sameness within the population, not overall health within the populations.

regarding elimination within f2 or f6, of deletrious Mendelian Traits. To my knowledge carriers can not be known from non-carriers, all on can do is remove affecteds, so through constant culling you would retain a 66% chance of any individual carrying the gene within generations.
66% chance of carrying offspring leaves lots of room to be desired with respect to cleaning the stock.
Hope I didn't miss anything you were trying to say.
Have a good Holiday weekend. If you write something and I don't respond it is because I am taking off for the weekend.
Matt

It happens in the wild more than you think. An adult male who can breed with multiple females each season and breeds for quite a few years can and will breed with his siblings and offspring. In a lot of species of snakes their little micro-habitat is quite small and don't venture out of that; others venture quite far. Why do all of the cal kings look similar around where I live in Chino Valley, AZ and this whole population looks different than the ones from Bagdad (which all look the same in their area?) - in-breeding. Look at locale (and in some cases isolated) rosy boas - in-breeding. Pyro locales - in-breeding. Snakes do in-breed in the wild. So do deer, raccoon, squirrels, rodents, etc....

As Terry pointed out, the negative traits can and will be passed on as well.

But to make a statement that in-breeding is bad (as breeders) is ignorant in the whole scheme of what happens in the wild.

I think that too many people are over-concerned about the whole in-breeding situation. Also people may not realize that a lot of in-breeding is occuring in certain species with CB animals since there were only "so many" wild-caughts that originally came into this country (and from the same locale) 30 years ago. A lot of CB animals are related.

Kerby...

Relatedness Does Not Equal inbreeding. Using your logic, everyone with blue eyes(very rare trait for human population at large) is related, also everone with widow peaks, those with dimples, and even redheads too.
You share traits with others in your family. Were you inbred? I'll bet, like me, you exhibit some recessive traits, does that mean you were inbred?
Animals can share traits without being bred directly to first relatives, even second relatives. There are differences between gene or trait amplification occurring within an isolated population(genetic drift) and inbreeding.
IMPORTANT: For herpers that means buying a pair of siblings for convenience and breeding them together later.

Again, POSSIBLITY a male can breed with multiple females, is NOT the PROBABILITY that he can breed with other females. Good thing there aren't any other males to breed with because of what? Your beloved mtn kings constrained to those mountain islands in the desert do not reproduce and attain maturity like those in aquariums. Their population is stable! Right? Means that over time, on average one breeding age adult is replaced with one breeding age adult. It does not mean one male breeds with three females, all progeny reach maturity, breed with each other, or even dad again. Possible? Yes. Probable? No.
In all this I see that you are saying that there is not a wealth of genetic material to be exchanged in a small population. True. But, mathematically, the probablities of damage from recessive lethal pairings go down dramatically even when animals are first cousins compared with siblings or parent-offspring matings.

About the examples of inbreeding occurring in mammals so often, look at some nature shows, pay attention to the social structure of the animals and how these structures downplay risks of inbreeding.

POSSIBILITY DOES NOT EQUAL PROBABILITY!

It happens in the wild more than you think. An adult male who can breed with multiple females each season and breeds for quite a few years can and will breed with his siblings and offspring. In a lot of species of snakes their little micro-habitat is quite small and don't venture out of that; others venture quite far. Why do all of the cal kings look similar around where I live in Chino Valley, AZ and this whole population looks different than the ones from Bagdad (which all look the same in their area?) - in-breeding. Look at locale (and in some cases isolated) rosy boas - in-breeding. Pyro locales - in-breeding. Snakes do in-breed in the wild. So do deer, raccoon, squirrels, rodents, etc....

As Terry pointed out, the negative traits can and will be passed on as well.

But to make a statement that in-breeding is bad (as breeders) is ignorant in the whole scheme of what happens in the wild.

I think that too many people are over-concerned about the whole in-breeding situation. Also people may not realize that a lot of in-breeding is occuring in certain species with CB animals since there were only "so many" wild-caughts that originally came into this country (and from the same locale) 30 years ago. A lot of CB animals are related.

Snakes do in-breed in the wild without regards if it's a sibling or off-spring, that is my opnion. You haven't mentioned anything to prove otherwise, it's just your opinion just like I have mine. It happens.

Kerby...

Just because a population of snakes shares certain similar characteristics doesn't necessarily mean that they are inbred. It just means that they are related and have similar genes. Populations of snakes in a given area will have similar appearances because the ones with the most cryptic camoflauge will tend to survive more and make more offspring than those who don't blend in as well - so the frequency of individuals with those genes will increase in the population.

Inbreeding probably does happen occasionally in the wild, often without negative consequences, but I think it is the exception rather than the rule. Also, continued inbreeding is probably worse than just one instance, since it is more likely that negative recessive traits will emerge in the offspring of inbred offspring.

This is evolution at it's finest, and it applies to much more than snakes.

Maybe someday, when I'm a herpetologist, I could do an experiment testing the effects of inbreeding on snakes and lizards...

Agree on some things. I never said it was the norm. But it does happen in the wild and IMO it happens more than we think. Others think otherwise, no big deal. But too many say "it is a bad thing and I want un-related pairs" and THAT statement is out in left-field.

So how many generations of testing in-breeding will show results????

Kerby...

Point was made. Can't convey a degree in genetics to you here on the forum. You have to do your own work towards that end.
Its one thing to disagree, but quite another to be oblivious to the laws of probability, statistics, population genetics,system dynamics, systems, genetics in general, etc.

That in-breeding doesn't occur in the wild, nor have you shown that in snakes in-breeding is bad. Don't throw your pompous "degrees" attitude into a discussion. You would be very naive to believe that in-breeding doesn't occur in snakes, deer, raccoons, etc....

So you are saying that the melanistc population of red fox squirrels in Marysville, KS is not from in-breeding?? Let's see... how did that recessive gene become so prevelant there???
They have been in-breeding.
Is it bad? They were there before the white man came to Kansas, still there and thriving (in-breeding and all). I used to trap in Kansas in the 70's and we used to trap cinnamon oppossum out of an area of a creek year after year. It is a recessive gene - in-breeding yes.

Ya see, we as humans can choose who we breed with and avoid in-breeding (to the best of our knowledge). Animals can not and do not.

Cheers.

Kerby...

We're related!!!
No, Don't say we're not. You can't prove we're not! It can be true. See you at Christmas!

The difference is that I'm not trying to change your mind....LOL

I'm supposed to have 2 thumbs????
I'd better get a new key-board.

Kerby...

Listen, all of us that have thumbs are coming over. Don't insult family. Don't dry out the turkey. I like an early Christmas dinner. I want a plasma tv for a present! You have plenty of time to shop and prepare. I need to spend the night too.

The good news is that I am not related to my ex-wife!!!

Agree to disagree.

Kerby...

Kind of jumping in a little late, but a feww messages up Kerby asks how many generations till damage becomes evident. In a few species of chameleons, inbreeding was/is a common practice as some species are hard to come by. In Meullers, I believe (have to look it up to be sure) poor results were attained by F3, with most offspring being very weak with a high mortality by F4 and F5. Just to clarify, take 2 animals, breed, offspring are F1, breed to siblings, their offspring are F2, so no confusion. Other species showed varrying results, so I guess you would need to hold back alot of offspring to check on, or need a bio lab capable of gene research to check them all.
I think alot of breeders try inbreeding to force out unique pattern trends they observed in one parent, only there is alot more to genetics than appearence, and we may be playing with something not quite understood.
Just my .02$
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Drew Z.
Member, NJHS