Monitors may be natural inbreeders…

[Steeve B]

First let me say that iv never studied them in nature and have never even seen them in nature, however many captive behavioural observations broth me to this conclusion, aim sharing my tots with you in hope that someone will shed more light on this subject. Expressing my tots in English so that everyone can understand my concept is quit unlikely, however ill give it my best trying not to omit any valuable information’s. Monitors start as eggs in a nest, even though we do not fully understand nesting, we do know about temps humidity and general egg husbandry, now hers some of my views, I think growing foetus can produce some heat, this allowing the middle eggs to stay a few degrees higher, possibly acting as sex determination, this natural process is altered when we separate eggs and place them side by side in incubators, next when eggs hatch I believe IMPRINTING is a key to varanids survival, many animals have a window of about few minutes to a few hours where IMPRINTING happens, usually imprinting is a maternal bond, however I believe it’s a social bonding tool for monitors, this allowing them to grow as a commune and eventually pair bonding and reproducing, there are some advantage for young monitors to grow in such commune safety being primary. Many things can bring us to this thinking, years of trying to pair up WC, or raising young WC monitors in pairs or group only to see them kill each other after a brief separation, same clutch monitors in general can be separated and reintroduced at will, even CB from deferent clutches are more difficult to mix. If we applied this logic to wild monitor populations, then most copulations are from siblings or from dominant males (father) as most intruders are aggressively chased away.
Pleas consider this as thinking out laude, contrary to many folks aim not afraid to be wrong.

Ps. I also think that inbred birds and reptiles can evolve and adjust to ever changing habitat faster

[Cake]

I am not sure if you are correct in saying that inbreeding would allow a species to evolve faster to a changing environment as it would bring about the expression of deleterious recessive alleles.

An alternate hypothesis to your imprinting one is that they imprint their siblings so as not to mate with them. They would not fight with one another due to their relationship with them in the fact that they share 50% of their genes with them. Their indirect reproductive gains are increased if they do not kill thier siblings, and further increased by killing unrelated individuals of the same sex.

Do your observations take into account whether the individuals are of the same sex?

Also is there TSD in monitors?, if so, is it species specific?, Is it type 1, or type 2?

I do not mean this as a slam, rather to incite debate and conversation.

[Steeve B]

Excellent its always fun to have a different view.

The following are by no means exactitude and may be outdated tomorrow, but for now there has never been any documented negative effects in inbreeding varanids, even though multi generation have been produced, some studies claiming inbreed syndrome are actually incubation and parental care faults.

Your alternate hypothesis makes sense but doesn’t correlate with my observations, I will surly keep these information’s in mind while I keep researching this matter.

Yes my observations includes both sex throughout development.

I don’t think TSD is significant with varanids, however I have reasons to believe ESD especially humidity plays an important role in sex determination, what I still need to learn is how a mass of eggs in a properly selected nest, is affected or can hold moisture (humidity levels can vary inside out of the egg mass)

???

[Jeff_Favelle]

After 100's of thousands of years of possible line/inbreeding in the wild, perhaps deliterious recessive allels have been "weeded out"?

And I think Steeve's theory may just apply to snakes, even more so. Anyone who has ever gone snake "hunting", knows very well that there are hot spots and pockets of snakes within the population. And obviously, they don't travel great distances, soooo what do you think may occur?

Good stuff. I totally agree, and have said so for years!

[Steeve B]

As I said many things led me to this conclusion and some aren’t monitor related, as Jeff stated snake can show us more about varanids then we may think!
Aim particularly interested in large pythons egg clutch, the way they stick and form a large mass, iv took temperature measurements in many clutches with females and the center was always warmer and drier then the outside, that’s with the female rapt around them, but this cant be conclusive as the data will vary from one set up to the next. Also theirs a variable with large pythons that correlate with my views, its blood pythons, each part of the year importers get only one sex then get animals of the opposite sex later, iv seen a similar trait in shipments with dumeril’s and beccari’s but not 100% like in blood’s.
This says a lot about how humidity can affect sex determination, I believe species with smaller clutches will have more chances to produce same sex animals, but then again they can produce many clutches at different time of the year, I who’d dough that species with 40+ eggs would produce all the same sex, this would have no value in nature as these species have little chance to double clutch and often will only breed biannually.
So there you have it! This is how I came to the conclusion the an egg mass surrounded by an insulating medium in a stable environment will manage its temp and humidity to the species advantage.

[crocdoc]

The temperature dependant sex thing is fairly easy to figure out: separate eggs from the same clutch and incubate them at different temperatures and/or humidities. I'm not into python breeding, but as it's been going on in captivity with some regularity for some time I'd be surprised if no one tried this, yet.


As far as monitors in the wild regularly breeding with siblings, speaking purely theoretically, it would be an extremely odd strategy from an evolutionary standpoint - reducing genetic diversity ultimately leads to extinction. Although there hasn't seemed to be any problem with captive monitors being inbred over the 10 or so years they have been bred with any regularity, that 10 years pales when compared to hundreds of thousands, if not millions of years.

Secondly, part of the problem with extrapolating captive behaviour to wild monitors is the assumption that conditions are the same in captivity as they are in the wild.

In the current instance, the assumption is that monitors that don't get along kill each other, therefore the need for an evolutionary tendency for sibling bonding to prevent this. In captivity, two monitors placed together may sometimes kill each other, because they can't get away from each other. In the wild, they wouldn't be near each other to start with, unless one of them was cycling or there was an abundance of food nearby (in which case they'd be concentrating on that and ignoring each other). If they didn't like each other, they'd move away from each other. Even if one gave chase, the other would likely get away. Even when one is cycling, they have the leisure of checking each other out slowly in the wild, rather than being locked in together.

The second thing is how we remember the data. We'll remember every time someone loses a monitor to an attack by another because it is such a shocking thing, but we forget the number of times animals are introduced that get along without a hitch. Unrelated animals killing each other is not the norm or we'd never risk introducing them. It's something that occasionally happens.

There is also the likelihood that two animals being introduced are unrelated: pretty high since related animals would usually be housed and raised together. Only in unusual circumstances would we raise siblings apart then reintroduce them and, even under those circumstances they'd recognise each other's smell.


It seems natural that animals get along better if they are raised together, but that's mostly habituation. If you wanted to keep a dog and a cat in the same house, for best results you'd raise them together from puppy and kitten rather than introduce them as adults in the confines of a room. It's not a reflection of what goes on in the wild, much as our captive monitors habituating to us isn't, either.

[kap10cavy]

Thats pretty much fits into what I have seen with my savs.
I have 2 that have been together for a number of months and get along great, although the smaller one will show his dominance on occassion. I recently got another and slowly introduced her to the others. I have had to remover her because the other two seemed to team up against her and she has a strong feeding responce, so things were going to get ugly.
She now has her own cage and spends her time eating, basking and trying to find a way out. Maybe one day I will find her a fella to keep her company.

Scott

[Jeff_Favelle]

reducing genetic diversity ultimately leads to extinction.

Not in all cases. Mutations happen all the time, adding more alleles to the "pool", and if all recessive deliterious alleles are weeded out, then there's no problem of them lining up due to inbreeding.

However, if the habitat changes, a genetically-low population is at an extreme risk. But I would never say that low genetic diversity leads to extinction. Nature is much too complicated for a bold statement like that.

[Siretsap]

Originally posted by Jeff_Favelle
Not in all cases. Mutations happen all the time, adding more alleles to the "pool", and if all recessive deliterious alleles are weeded out, then there's no problem of them lining up due to inbreeding.

However, if the habitat changes, a genetically-low population is at an extreme risk. But I would never say that low genetic diversity leads to extinction. Nature is much too complicated for a bold statement like that.

The problem with the low genetic diversity is it has the bottle neck effect, it will continue till all the genes are exactly the same (alsmot like each animal is a clone from the other). I know that there are some types of mamals that have this problem (certain wild cats). If all were to have the same gene pool, then as soon as one would contract a virus and can't overcome it (cause if you talk about inbreeding, then you mean all the animals from this species are in the same area and no where else), then you risk extinction. So yes in a way inbreeding does cause extinction.

[lostwithin]

From what I have read and learnt genetic diversity is what allows a population to evolve, many natural safe guards have evolved along with species to help avoid inbreeding within populations.
I am certain it does occur in wild populations but if it were to become more then a random event it would surely lead to a species eventual evolutionary demise. Genetic mutations do occur and that would add some variability into a population but it does occur enough that it would introduce any significant amount of variation, any first year biology text could explain it much better then I.
In then end it has been shown in many studies that diversity is the key to evolutionary success, of a species. Inbreeding causes less and less diversity bringing a halt to the evolutionary process.

That is the reason species don’t inbreed if it can be helped the cause of this lack of attraction to family members is beyond my capabilities of explain. In theory if reptiles were "hotwired" to actually do the opposite and there drive was to increase inbreeding there would be no diversity, they wouldn’t have evolved into he species that occupy almost every corner of the habitable world.

Now as a final argument I will use plants as an example, just to show how plants avoid inbreeding at all costs, I don’t know if there are any others with significant knowledge of botany but plants have evolved several amazing methods of avoiding inbreeding, In some flowering species the genotypes of pollen are detected and any that originated from related flowers are stopped before they reach fertilization. There are other way that plants avoid inbreeding I just found this one most fascinating. In the end the point is every living thing is hardwired to avoid inbreeding, as it eventually leads to the demise of a species.

Devon

[Steeve B]

Not so long ago I use to call every ackies (little mongrels) even if all looked healthy, I guess it was stubbornness on my part, refusing to envision other possibilities including possibilities that have been dismissed as otter nonsense, anyhow for this I started looking at reptiles breeders around the world, the funny thing is all of them have produced several generations of inbreeding with as many species and none have experienced inbreed syndrome. Iv talked with amphibians breeders colubrides boas pythons turtles tortoise lizards and plenty of bird breeders (these are the closes to varanophil) what have I learned from them? Plenty, first the more experienced think nothing about inbreeding, in this group you have very knowledgeable peoples, one in particular is a dna blood specialist (sorry don’t know the term) anyway he’s been and endless source of information to me, Hers a question? Who knows how proteins and sugar and all vitamins and minerals can affect blood? Ad to this individual metabolism and environments, you now have an infinite variable. Its next to impossible that different animals synthesise these the same way.

Next; captive monitors behave the way there species evolved, sure they are confined but they use inherited behaviours, these behaviours are millions of years old and passed by genetic, this even before they evolved into separate species on different continents, why do you think they all have somewhat similar body language similar threat display courtship and nesting, you have termites nesters in Africa, Asia, Australia and all these species can if they need too! Nest in the ground or in trees, This is inherited behaviour to me.

Perhaps what I most enjoy about these forums is the endless information’s we exchange! How boring it would be if we all tot the same way.

[kap10cavy]

A simple reason why I don't believe inbreeding will lead to extinction. Reptiles were here before we were. They were doing this then and will be doing this long after we are gone. I am more concerned with habitat desrtuction than some lizards that pretends to live in the moutains of West Virginia.
Maybe someone will teach them to play the banjo.
Maybe thats why we like them so much here in the south. Hahaha

Scott

[Cake]

A great deal of prefessional breeders intentionally inbreed their animals to express recessive alleles (Take BP's for example). In captivity the genetic diverstiy of the species is not of a great concern as they do not need to evolve to changing conditions. The genetic diverstiy of a natural population needs to be more variable, as these species are still subject to natural selection and not artificial as with captive animals.

[mbayless]

Scott,

If you inbreed with your sister you will see traits good and bad compounded = and that is why in many states, maybe not Tennessee it is illegal to marry your sister, but of course in others it is encouraged! (haha).... these negative traits often cause full term births to abort, or in varanids: perhaps cause a DIE scenario (full term baby die-in-egg!)? Think about it...Darwinism encourages genetic diversity, and if you reduce this diveristy, you move toward extinction!

Cheers,
markb

[Scales Zoo]

Further on Jeffs posts about snakes in the feild.

Rattlesnakes out here, leave their dens in the spring, go up to 20 miles (30 kms) away, and come back and go down the exact same hole that fall. They also breed at these den sites, and near by rookeries.

There was a study done in Texas that I was reading about.

A lot of rattlesnakes were raised seperately for 3 years. There were 2 groups that were related, and then 1 group of unrelated snakes. They were all microchipped. In 3 years time, after never being around one another, they were all dumped in a large room together. The family groups paired up, and the ones not related were searching around the room, or laying by themselves.

My guess is Rattlesnakes, and many other snakes, do inbreed for generation after generation. Maybe they are doing it on purpose. After weeding out the bad alleles, maybe they have an advantage over most other types of life that have not.

Ryan