Hybrid?

[Doritoinmontucky]

I was wondering if anyone has heard of cross breeding tortoises? If so what breeds and what would you call the outcome? I'm just curious if anyone had ever heard of this. I have never read a book that says anything about it. any info would be greatly appriciated. Thanks.

-Derrik

 

[dmmj]

One of our members (N2torts) I believe has some sulcata and leopards crosses.

 

[Tom]

Yes it happens. I don't think it should.

 

[Doritoinmontucky]

Does it cause Defects that are not healthy for the hatchling tort?

 

[Tom]

Not that we know of. It just dilutes/pollutes a finite gene pool.

 

[Doritoinmontucky]

True, I didn't really think of it like that...

 

[GBtortoises]

"Yes it happens. I don't think it should."---Ditto

"It just dilutes/pollutes a finite gene pool."---Ditto again

 

[N2TORTS]

Wonder what the human gene pool would be if "stuck" to our "own breed" ? ........

EX: French , English , German .....and Race ...... Not so pure eh ?

 

[Yvonne G]

Wonder what the human gene pool would be if "stuck" to our "own breed" ? ........

EX: French , English , German .....and Race ...... Not so pure eh ?

Not the same thing. We're all human species. Tortoises don't come in "breeds," and are different species.

 

[GBtortoises]

Humans did stick with their own breed last I knew.

 

[Madkins007]

Many species of animals naturally crossbreed under certain conditions- similar enough species that they can confuse courtship signals, close proximity, usually a fringe area so fewer choices in their own species, often some other sorts of pressure to sort of force them together- like loss of habitat.

I am not aware of any examples of this in wild tortoises, although there is some evidence in the DNA that it happens with Red- and Yellow-foots. It could happen in other areas, I just don't know about it.

Captivity often simulates the above conditions, and some keepers try to cross-breed. The result is generally referred to as a cross and the species name is written with both names and an 'x', as in Chelonoidis carbonara x denticulata

My personal opinion about crossbreeding is that if we had a big gene pool to play with, a rock-solid knowledge of breeding and incubation needs, and had a breeding plan to improve the hobby (smaller, hardier, etc.), it would not bother me, but I personally am really troubled by 'cosmetic' cross-breeding and by casual cross-breeding- but again, this is just my opinion.

 

[Doritoinmontucky]

Thanks for the opinions!

 

[GBtortoises]

There are examples of cross breeding having taken place in the wild between Testudo marginata and Testudo ibera although extremely limited. It has also always been accepted that Testudo hermanni and Testudo horsfieldi can successfully breed in captivity although I've never seen resulting offspring.

"My personal opinion about crossbreeding is that if we had a big gene pool to play with, a rock-solid knowledge of breeding and incubation needs, and had a breeding plan to improve the hobby (smaller, hardier, etc.), it would not bother me, but I personally am really troubled by 'cosmetic' cross-breeding and by casual cross-breeding- but again, this is just my opinion."

Mark, if you don't mind I'd like to "borrow" your opinion! I could not have said it better.

 

[Doritoinmontucky]

Having two different backgrounds may have effects on behavior as well. A tort with two backgrounds might feel confused...out of place. Lol I wouldn't like that...

 

[N2TORTS]

Wonder what the human gene pool would be if "stuck" to our "own breed" ? ........

EX: French , English , German .....and Race ...... Not so pure eh ?

Not the same thing. We're all human species. Tortoises don't come in "breeds," and are different species.

Yvonne....actually ~ A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions.That definition of a species might seem cut and dried, but it is not—in nature, there are lots of places where it is difficult to apply this definition.Also, many plants, and some animals, form hybrids in nature. Hooded crows and carrion crows look different, and largely mate within their own groups—but in some areas, they hybridize. Should they be considered the same species or separate species?There are lots of other places where the boundary of a species is blurred. It’s not so surprising that these blurry places exist—after all, the idea of a species is something that we humans invented for our own convenience!

Heterosis ( hybrid vigor ) is a scientifically proven reality that minimizes the likely hood of genetic disease and boosts over all health, vigor, even size. A magnification of the gains had by incorporating divergent lines within breed. That said, it is no magic bullet. Crossing breed lines won’t make two dumb dogs smart, nor two cowardly dogs brave. Garbage in will get you garbage out; albeit healthier, possibly more sound…garbage.

As far as breeds are concerned ....
A breed can be defined as "a homogeneous grouping of animals within a species, developed by humans, a line of descendants perpetuating particular hereditary qualities."

JD~

---

Many species of animals naturally crossbreed under certain conditions- similar enough species that they can confuse courtship signals, close proximity, usually a fringe area so fewer choices in their own species, often some other sorts of pressure to sort of force them together- like loss of habitat.

I am not aware of any examples of this in wild tortoises, although there is some evidence in the DNA that it happens with Red- and Yellow-foots. It could happen in other areas, I just don't know about it.

Captivity often simulates the above conditions, and some keepers try to cross-breed. The result is generally referred to as a cross and the species name is written with both names and an 'x', as in Chelonoidis carbonara x denticulata

My personal opinion about crossbreeding is that if we had a big gene pool to play with, a rock-solid knowledge of breeding and incubation needs, and had a breeding plan to improve the hobby (smaller, hardier, etc.),

Very well said Mark !

~

 

[GeoTerraTestudo]

Yvonne....actually ~ A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions.That definition of a species might seem cut and dried, but it is not—in nature, there are lots of places where it is difficult to apply this definition.Also, many plants, and some animals, form hybrids in nature. Hooded crows and carrion crows look different, and largely mate within their own groups—but in some areas, they hybridize. Should they be considered the same species or separate species?There are lots of other places where the boundary of a species is blurred. It’s not so surprising that these blurry places exist—after all, the idea of a species is something that we humans invented for our own convenience!

Heterosis ( hybrid vigor ) is a scientifically proven reality that minimizes the likely hood of genetic disease and boosts over all health, vigor, even size. A magnification of the gains had by incorporating divergent lines within breed. That said, it is no magic bullet. Crossing breed lines won’t make two dumb dogs smart, nor two cowardly dogs brave. Garbage in will get you garbage out; albeit healthier, possibly more sound…garbage.

As far as breeds are concerned ....
A breed can be defined as "a homogeneous grouping of animals within a species, developed by humans, a line of descendants perpetuating particular hereditary qualities."

JD~

Some inaccurate statements there (and btw, no need to shout).

Although it is true that the concept of a species is artificial, it does reflect a reality. As was stated above, tortoises do not come in breeds, only species, subspecies, and regional variants. Breeds are varieties that have undergone artificial selection (human-induced evolution) from a single-species origin, often a single subspecies or race. Natural selection, on the other hand, can occur over longer periods, and can ultimately result in bigger genetic differences (although not necessarily bigger morphological differences).

Some closely related species or subspecies of turtles can hybridize in nature (e.g. box turtle subspecies; leopard tortoise subspecies; occasionally Russian and Hermann tortoises). These may occur in natural zones of intergradation, or may be more rare occurrences, depending on how closely related they are and where they're located.

Bottom line, if two animals are closely related enough, they may readily hybridize and have healthy offspring. In captivity, though, a lot of animals may be lacking for mates, and so might mate with a partner with whom they would not choose in nature. This is a problem because:

- The offspring may be unhealthy, or have partially or completely reduced fertility.
- Even if healthy, the animal may not be as well-adapted to the environments from which each parent species originated.

If you view pets as merely pets, then as long as the animal is healthy, you might not consider this to be a problem. However, if you view captivity as a kind of "Noah's Ark" for animals that may be threatened in their natural habitat, then you would not want to hybridize them, because that can negatively impact their survivability in the event that they are to be rewilded.

Humans interbreed all the time because we are all members of the same subspecies (Homo sapiens sapiens), with only clinal (regional) differences. Different box turtle subspecies are known to hybridize in zones of intergradation, as are leopard tortoises. Dogs can mate between breeds because they are all members of the same species, their breeds having diverged quite recently in history.

But different naturally occurring species have been reproductively isolated from each other for hundreds of thousands to millions of years. Leopard tortoises are not very closely related to sulcata tortoises, and yet people have been hybridizing them in captivity. I disapprove of this practice, because it artificially yields animals that are intermediate between their parents, and therefore lack their adaptations. In my opinion, this should not be done. Hybridization between closely related subspecies or races may be acceptable under some circumstances, but in general we should try to maintain close to the kind of genetic diversity that animals would be encountering in nature. Shrinking it may result in inbreeding depression, and enlarging it may result in infertility. Best to try to follow Mother Nature's lead in most cases.

 

[dmmj]

don't most hybrids end up sterile? what is it that a horse and donkey make, mules? aren't they sterile?
I would be interested to know if the leocattas will end up sterile.

 

[fbsmith3]

Well, scientists have said:
-a hybrid between a human and a Chimpanzee can produce fertile offspring.
-While a hybrid between a human and a gorilla will most likely not produce fertile offspring.

Either way it’s a very cool concept, I still would NOT want to marry a chimp or a gorilla. Just because something can be done or is interesting does not mean it should be done.

 

[GeoTerraTestudo]

don't most hybrids end up sterile? what is it that a horse and donkey make, mules? aren't they sterile?
I would be interested to know if the leocattas will end up sterile.

I wouldn't be surprised if "leocatas" (they have a name?) are sterile, but I don't know.

A lot of hybrids do have partially or completely reduced fertility, yes. This results when the parent species have a different number of chromosomes. Horses (Equus ferus caballus) have 64 chromosomes and donkeys (Equus africanus asinus) have 62. The resulting offspring (a mule or a hinny) has 63 chromosomes. This causes problems during meiosis, or the special type of cell division that produces sperm and egg cells.

Interestingly, Przewalski's wild horse (E. ferus przewalskii) has 66 chromosomes, but they not only form fertile hybrids with domestic horses, they are also considered to be merely a different subspecies within the same species! This is because they have undergone a Robertsonian translocation in the relatively recent past, which split up two of their chromosomes into four. However, this did not change the genetic information very much, so the divergence was slight.

Some hybrids have reduced fertility, even with the same number of chromosomes. Wolves/dogs (Canis lupus) can hybridize with coyotes (C. latrans) and golden jackals (C. aureus), but the offspring usually experience an incomplete reduction in fertility, even though all these canines have 78 chromosomes. This is probably due to a mismatch in where the genes are physically located on the chromosomes.

Lions (Panthera leo) and tigers (P. tigris) can famously form a sterile hybrid called a liger or tigon. Although handsome, these animals usually have poor health. The media doesn't report on it, but they usually die young, too. They also have unpredictable behavior, probably due to the social behavior of lions and the solitary behavior of tigers.

Bringing it back to turtles, I wouldn't want to subject a tortoise to the kinds of problems that hybrids in other animal groups face. From infertility to cardiovascular disease to confused behaviors, I don't think hybrids from distantly related species have a particularly high quality of life. Like I said, best to perpetuate healthy animals that come from the same source population, or if inbreeding depression is evident, outcross with another population from the same species, or maybe another subspecies at the furthest. But not another species. That would likely be problematic.

 

[dmmj]

Personally I prefer liger