Inbreeding

[sprdonkey]

Back in 2001 or 2, something like that, I got my first pair of Corns. About 3/4 of the way down my mistifying little bubbble gums spine there was a lump. I was understandably concerned. My friend michelle said that she had picked them out for me and not to worry, that sometimes they hatch out with little kinks in their spine which range from harmless to fatal but she had examined the spot and was positive that it was simply a calcium deposit on the bone and may even go away as the snake got older. I trusted her an she was right, either it went away or she outgrew it. At the time however, she brought up something that I took to heart and will never forget. Inbreeding in people causes usually obvious defects. Defects that in dogs, cats, horses, birds etc...might not be so obvious. Take snakes for example, we manipulate the bloodlines, we breed and then we backbreed and then if we have too we sideways breed (mother x father, father x daughter, daughter x brother...) to get the quad homo morph of the century. She told me that after a few generations, it is best to simply find and add and add new blood to keep the lines strong, she does it before she reaches 4 or 5 gens. I only think of this now because of the seemingly high rate of defects this year. What does everybody else think about this?

 

[toyah]

Inbreeding does not cause deformities or genetic problems - but it can bring to the surface genetic problems that are carried by the parent snakes. So if you buy a healthy snake from a pairing of closely related snakes, then statistically, that snake is LESS likely to hide any genetic abnormalities then a snake from an outcross (unrelated parents).

Remember as well things like feeding response, size, fertility, etc, are all also partially governed by genetics. If you inbreed on a pair of snakes that are big, strong snakes with great feeding responses, then you're more likely to produce more of the same. But if you inbreed on weak runty snakes that don't feed well, then you'll most likely get more of those instead.

Inbreeding is a great tool to use responsibly to produce good quality animals - it just needs, as any breeding does, thought and care put into the matings you're doing to ensure you get the best offspring possible from it.

 

[Velvet]

I think that breeding with two healthy related snakes is better than breeding with two unrelated weaker snakes.

I think most breeders strive for the best so when inbreeding, they will only do so with the best they have available.

You are more likely to get snakes with defects like kinks etc etc if you breed with animals who have a family history of the defect than if you bred with a pair of related snakes with no family history of a defect...

Besides, I have read that some defects can be due to incubation temps as well, not just genetics.

 

[Cegninedorf]

This is kinda off the topic, but also somewhat related: last night, I was watching "The Outsiders" with John Quinones (ABC? A show kind of like "Dateline", etc...) and a segment discussed GSA -- Genetic Sexual Attraction, where essentially, like genes attract like, mostly though, with genetically related people who have been separated for a significant amount of time (usually since birth) and find each other later on and become sexually attracted to one another. One doctor wrote a report stating that even in humans, unless the two carriers carried some hidden recessive gene that they both shared, it's just as unlikely that a brother-sister coupling would give birth to children that have some kind of "defect" as any other unrelated coupling might do. The doctor also stated that consanguinous couples only had a 2% greater increase in having children with hemophilia than couples who were not consanguinous.

I mention this in part because since joining this forum a year ago, I was interested and mildly curious as to breeders breeding snakes from the same "family." And, I just read a ton of books on the disgusting genetic mess that the royal families of Europe made for themselves...so, thinking that it's not good for siblings or cousins to mate, I wondered the same about other animals. And now having seen the aforementioned report, I guess it's quite all right for *all* animals to mate with one's sibling.

Hmmm...more stuff to mull while dealing with the morning's traffic, I imagine...

 

[rolandslf]

Firstly, I agree with what everyone says'. My viewpoint is this, we need to inbreed so as to strengthen certain traits and genes in a particular bloodline.
Secondly you will find that most corn snakes nowadays are Het for so many different Morphs that it would take more than a few generations of inbreeding to really cause any genetic defect, just my 2 bits worth.
Off subject, Meg check out the change in my location under my name, and proudly so.

Ciao

 

[sprdonkey]

It's great to find such broad and diverse, not to mention well supported opinions on a subject like this. This is'nt meant to be a right or wrong question, simply a food for thought question. I am glad that people are posting.
It is true that there is evidence supporting longevity, general hardiness, feeding response, size, etc...as being transferable via heredity. However, say you find a great morph, you only have a couple to start with and ofcourse, first and foremost, you are going to want to facilitate it. We don't really have a choice in this instance. But say in the F3 generation you find that your hatchlings are a little smaller, more fragile, you might see increased reluctance to feed, slightly less muscle tone or retarded growtrh rates despite optimal conditions... Telltale signs that we have spread the bounty a little thin?

 

[snakewispera snr]

But say in the F3 generation you find that your hatchlings are a little smaller, more fragile, you might see increased reluctance to feed, slightly less muscle tone or retarded growtrh rates despite optimal conditions... Telltale signs that we have spread the bounty a little thin?

I'm on the look out for a pair of Indigo's. Today I was talking to my supplier about Indigo's (he used to breed them so I wanted to know everything)
He warned me off, saying the genetic line had become too thin in the U.K. due to lack of new blood coming into the country. He gave up on them a few years back due to kinks etc.(he said at least 60% of hatchlings went that way) I have no proof of this, only his word. But I've no reason to disbelieve him, he's a good guy.
MIKE

 

[rosecat]

another way to look at this is that even if the snakes don't visually have an abnormality, breeding full siblings or parent to offspring increases the chance of the resulting offspring carrying the "bad gene".

when inbreeding snakes there is an increased percent chance in the possibility of the related snakes carrying the same gene, the % increases or decreases based on the distance of the relations between the two snakes.

So if you have 2 snakes that full sibs and are each 50% ph anery, and breed them together you actually have a higher chance of both snakes being ph anery than you do if you bred unrelated snakes that are both 50% ph anery

~rosecat

 

[Blue Apple Herps]

So if you have 2 snakes that full sibs and are each 50% ph anery, and breed them together you actually have a higher chance of both snakes being ph anery than you do if you bred unrelated snakes that are both 50% ph anery

??? If they're both 50% possible het anery, then they're both 50% possible het anery regardless if they are siblings. There's not a higher chance of siblings being 50% het anery vs. unrelated pairs that are 50% het anery.

 

[Msterry]

It's great to find such broad and diverse, not to mention well supported opinions on a subject like this. This is'nt meant to be a right or wrong question, simply a food for thought question. I am glad that people are posting.
It is true that there is evidence supporting longevity, general hardiness, feeding response, size, etc...as being transferable via heredity. However, say you find a great morph, you only have a couple to start with and ofcourse, first and foremost, you are going to want to facilitate it. We don't really have a choice in this instance. But say in the F3 generation you find that your hatchlings are a little smaller, more fragile, you might see increased reluctance to feed, slightly less muscle tone or retarded growtrh rates despite optimal conditions... Telltale signs that we have spread the bounty a little thin?

Id be very interested in reading the studys done on feeding responces. I assume they were done with the same pairings over several yrs. Could you tell me where i could find those studys please??.....Thank you..

 

[CaptBogart]

There is a local breeder that I was inquiring about this with when he offered me a deal on F4 sibs, because they wouldn't be available again for awhile. Of course I said, "Huh?", and was told they never go more than five generations before outcrossing new blood to the mix, usually W/C.... Then they recapture the line and start again... I haven't thought about it in a long time until the 4-5 comment above...

 

[MegF.]

While I believe that in the wild there is a considerable amount of inbreeding, I always think it's important to outcross where possible to create the strongest lines possible. Snakes territories are relatively small (although they do cross other territories) and some species like rattlesnakes return to the same area they were born to breed and hibernate. They have to be breeding with a related snake at some point. I think this makes a snake far more resistant to genetic mutations and anomalies due to inbreeding than say a mammal. I have noticed among some types of snakes though, that extensive inbreeding to bring out a trait is beginning to create animals that either are porducing non-fertile eggs, or eggs where the baby dies in later development. Where possible, I think in order to keep the species strong and viable, it's necessary to outcross.

 

[zwyatt]

Inbreeding does not cause deformities or genetic problems - but it can bring to the surface genetic problems that are carried by the parent snakes. So if you buy a healthy snake from a pairing of closely related snakes, then statistically, that snake is LESS likely to hide any genetic abnormalities then a snake from an outcross (unrelated parents).

This doesn't make any sense. First off, a healthy inbred snake is more likely to be harboring recessive deleterious alleles. The whole point is that inbreeding promotes the inheritance of these alleles. So, statistically, an inbred snake is more likely to have hidden recessive alleles than an outcrossed individual. Saying that a snake is less likely to hide genetic abnormalities is not quite the same as saying that a snake is more likely to express genetic abnormalities.

Remember as well things like feeding response, size, fertility, etc, are all also partially governed by genetics. If you inbreed on a pair of snakes that are big, strong snakes with great feeding responses, then you're more likely to produce more of the same. But if you inbreed on weak runty snakes that don't feed well, then you'll most likely get more of those instead.

While this may be valid to a degree, there is no need to suggest that inbreeding is the way to go about improving traits. If these traits like feeding response, size, etc are controlled by the same genes in all corn morphs (which they probably should be), then outcrossing two unrelated snakes with strong feeding responses should be just as useful as inbreeding two snakes with strong feeding responses, and the same holds true for outcrossing two unrelated weak snakes.


I don't mean to suggest that I think inbreeding is wrong or not useful, because I believe it does have its uses. Some of what you stated just didn't gel with what I consider the complete story.

This is kinda off the topic, but also somewhat related: last night, I was watching "The Outsiders" with John Quinones (ABC? A show kind of like "Dateline", etc...) and a segment discussed GSA -- Genetic Sexual Attraction, where essentially, like genes attract like, mostly though, with genetically related people who have been separated for a significant amount of time (usually since birth) and find each other later on and become sexually attracted to one another. One doctor wrote a report stating that even in humans, unless the two carriers carried some hidden recessive gene that they both shared, it's just as unlikely that a brother-sister coupling would give birth to children that have some kind of "defect" as any other unrelated coupling might do. The doctor also stated that consanguinous couples only had a 2% greater increase in having children with hemophilia than couples who were not consanguinous.

You know, I had wanted to see that, but then I missed it. I've been studying mate choice and sexual selection for several years now. Like genes can attract in certain cases, but not all. A lot of these studies are done on scent and the outcome of the study often depends on the index upon which the study subjects are asked to judge the scents. While there are instances where people prefer similar individuals, ther e are also studies that show that people chose mates that have different genetic make-up than their own.
That doctor's statement: "unless the two carriers carried some hidden recessive gene that they both shared, it's just as unlikely that a brother-sister coupling would give birth to children that have some kind of "defect" as any other unrelated coupling might do." is pretty irresponsible, imo. The whole point is that related individuals (brothers and sisters) are statistically more likely to be carrying the same recessive alleles. :bang:

 

[MegF.]

This would hold particularly true in diseases that require the combination of two recessives like sickle cell and cystic fibrosis. If you had a brother and sister, each with the recessive gene for either of these diseases (they would show no signs of the disease, but carry the potetial to pass it on), chances are good their children would show the active signs for the disease. This would not be true if they had children by someone who did not carry a gene at all.

 

[Ziya]

At the time however, she brought up something that I took to heart and will never forget. Inbreeding in people causes usually obvious defects. Defects that in dogs, cats, horses, birds etc...might not be so obvious. Take snakes for example, we manipulate the bloodlines, we breed and then we backbreed and then if we have too we sideways breed (mother x father, father x daughter, daughter x brother...) to get the quad homo morph of the century. She told me that after a few generations, it is best to simply find and add and add new blood to keep the lines strong, she does it before she reaches 4 or 5 gens. I only think of this now because of the seemingly high rate of defects this year. What does everybody else think about this?

Inbreeding doesn't cause defects, genetics does. Inbreeding is to get more like pairings genetically. This can produce awesome or it can have serious problems depending on the animals.

If 2 related dogs are bred carrying a defect it will be obvious through their offspring, it will be hereditary and likely that pairing the related dogs it will show. That is the reason health test are done before breeding. Defects of inbreeding and poor breeding in other animals is obvious. You can successfully inbred dogs with great out come when using health testing/knowing your lines. But if you just inbreed two dogs you know very little about they might be carrying a defect and out it comes. Inbreeding doubles up on the good but also on the bad. This should be true in snakes too and most other animals. Genetics are a factor when breeding no matter what method you are using. So it should be obvious what defects are being carried as they will get passed down more likely from a related animal vs unrelated. All that outcrossing would be doing is hiding something since the genes are not like.

Some people believe cross breeding (not outcrossing) make "healthier animals" especially in the dog world. This is one thing designer dog breeders claim but it is really untrue. Certain things might be hidden when you don't inbreed but even out crossed dogs can have hereditary problems and so can cross breeding. If you breed a Rottweiler to a Bullmastiff that both have Hip Dysplasia then the pups will also have HD, just because the parents are totally unrelated from 2 different breeds isn't going to stop them from passing it on.

I think that before you breed any animal you need to learn as much as you can about it. About that species, about your individual and their history and as much about breeding as you can. This will ensure your best out come and you can make the wisest decision for a particular breeding.

 

[toyah]

This doesn't make any sense. First off, a healthy inbred snake is more likely to be harboring recessive deleterious alleles. The whole point is that inbreeding promotes the inheritance of these alleles. So, statistically, an inbred snake is more likely to have hidden recessive alleles than an outcrossed individual. Saying that a snake is less likely to hide genetic abnormalities is not quite the same as saying that a snake is more likely to express genetic abnormalities.

Inbreeding increases homozygosity. It doesn't make a snake more likely to "harbor" recessive deleterious alleles, it makes it more likely to EXPRESS those genes only if the deleterious alleles already exist in the genepool. It doesn't promote inheritance of deleterious alleles, it just simply increases the homozygosity of them - which would of course in the case of recessive "baddies" allow responsible breeders to identify that they exist in a particular genepool and select against them. As much as inbreeding will increase homozygosity of deleterious alleles that exist in a particular genepool, it will also increase homozygosity of non-deleterious alleles that exist in a genepool.

The problem with inbreeding I think is I have no idea how inbred particular snakes are. Even if I buy a lavender from one breeder and its mate from another breeder on another continent, for all I know they could be double first cousins. I have seen people advertise "unrelated pairs" for sale of particular morphs, only to find out they have two clutches from two females, but both have been bred to the same male! I wish we handed out pedigree sheets as standard, like the GTP people ... would make it a lot easier to plan matings using more information than just the snakes we have in front of us.

 

[MegF.]

I think that is what the cornsnake registry is trying to do, and as far as pedigrees in GTP, it just proves how much inbreeding is going on in my opinion. We are starting to see a lot of problems in certain lines, and I'm using extreme caution when buying animals from known lines.

 

[Ziya]

Inbreeding increases homozygosity. It doesn't make a snake more likely to "harbor" recessive deleterious alleles, it makes it more likely to EXPRESS those genes only if the deleterious alleles already exist in the genepool. It doesn't promote inheritance of deleterious alleles, it just simply increases the homozygosity of them - which would of course in the case of recessive "baddies" allow responsible breeders to identify that they exist in a particular genepool and select against them. As much as inbreeding will increase homozygosity of deleterious alleles that exist in a particular genepool, it will also increase homozygosity of non-deleterious alleles that exist in a genepool.

The problem with inbreeding I think is I have no idea how inbred particular snakes are. Even if I buy a lavender from one breeder and its mate from another breeder on another continent, for all I know they could be double first cousins. I have seen people advertise "unrelated pairs" for sale of particular morphs, only to find out they have two clutches from two females, but both have been bred to the same male! I wish we handed out pedigree sheets as standard, like the GTP people ... would make it a lot easier to plan matings using more information than just the snakes we have in front of us.

That is so true about inbreeding. Good post.

As far as the pedigrees I agree as well, it would make things so much easier. If I didn't have pedigrees on the dogs I think I would lose my mind and end up breeding some breed some not so good stuff. I think with the cornsnake registry hopefully more people will start keeping track. There are a few people that already keep their own pedigrees but if it were standard it'd be a lot more helpful. Knowing where an animal comes from and whats behind it helps so much in planning the future.