Hybrid?

[GeoTerraTestudo]

GC News: February 3, 2010
Team of Veterinarians Prepare Hybrid Tortoises for Release on Pinta Island in 2010
In November 2009, a group of veterinarians, working with the Galapagos National Park (GNP), prepared 39 hybrid tortoises slated to be the pioneer group to initiate the return of tortoises to Pinta Island. Project Pinta is a multi-year project aimed at the restoration of the island following the successful eradication of goats on Pinta in 2003. While complete island restoration will require the eventual repopulation of Pinta with a reproductive tortoise population, scientists and managers are awaiting the final results from genetic analyses of a massive sampling of tortoises before making the final selection of which tortoises to use. To initiate the return of tortoises, critical ecosystem engineers during this important period of vegetative recovery, a special group of tortoises will be released onto Pinta. To ensure that this group of hybrid tortoises will not compromise any future efforts to reestablish a reproductive population, veterinarians sterilized them.

Yes, because humans have decimated island tortoise populations on both the Galapagos Archipelago and the Seychelles Archipelago (which includes Aldabra), restoration efforts often involve using tortoises from nearby islands when the native population/subspecies is extinct. This is similar to other restoration projects, like the one that reintroduce peregrine falcons to the Great Plains after DDT, using falcons from other locations. When the native animals are gone, the next best thing is to use the next closest relative as a replacement.

Notice, however, that the veterinarians sterilized the tortoises in the project mentioned above, so as not to compromise any future restoration efforts.

There is talk of doing similar Pleistocene Rewilding in parts of the US and Europe using modern relatives of extinct mammals (bolson tortoises, horses, camels, llamas, elephants, cheetahs, and lions). This is controversial, but again, the justification is that since the ecosystems are disturbed due to human activity, it is justifiable to use closely related proxies when the native animals are extinct. Interesting topic, and one that I am involved in, but we can save discussions on reintroducing bolson tortoises, horses, and cheetahs for a Debatable Topics thread some other time.

 

[dmmj]

Why would they sterilize them?

 

[GeoTerraTestudo]

Why would they sterilize them?

So they don't hybridize with full-blooded tortoises native to that island. There are some differences in these closely related tortoises from one island to another, like shell shape that effects whether they graze or browse. These restorationists have eradicated goats, which is a good first step, and are now introducing hybrid Galapagos tortoises to restore the native plant-animal cycles on the island. However, because they plan on eventually reintroducing full-blooded animals later on, they don't want these hybrids to breed with them.

Not sure I entirely agree with this approach, but if they have enough animals to work with, then it does make sense.

This is why hybrid animals cannot be used for rewilding. They lack the adaptations of their parents, so except for last-ditch efforts, they do not qualify as stock for reintroduction. This is actually the problem with bison restoration today in America. Most bison have some cattle introgression, or genes in them from cattle due to hybridization projects in the past. These animals are ineligible for introduction into national preserves or parks, like Yellowstone, which have only completely native, pure-blooded bison. Again, might be a bit too cautious in some cases, but overall a good management policy for wildlife conservation.

 

[Neltharion]

Why would they sterilize them?

To ensure that they don't reproduce. It appears that this group of hybrids are guinea pigs to see if the island will sustain a tortoise population. Once its been established that it will, a legitimate species will be placed on there. It would appear that this hybrids are deemed to be expendable.

 

[N2TORTS]

Why would they have to sterilize Hybrids if " they are mules" as some folks think ?

 

[GeoTerraTestudo]

Why would they have to sterilize Hybrids if " they are mules" as some folks think ?

Well, remember, Galapagos tortoises are all very closely related to each other ... at the subspecies level, like different types of box turtles. Again, this is a far cry from the relationship between sulcatas and leopard tortoises, which are at least in different species, if not in different genera. Time will tell, but I would be surprised if a "lepracutta" turns out to be fertile. Galapagos tortoise hybrids may be thought of as merely mutts; it's the kinds of hybrids you find in the pet trade that may be likened to mules.

 

[N2TORTS]

Why would they have to sterilize Hybrids if " they are mules" as some folks think ?

Well, remember, Galapagos tortoises are all very closely related to each other ... at the subspecies level, like different types of box turtles. Again, this is a far cry from the relationship between sulcatas and leopard tortoises, which are at least in different species, if not in different genera. Time will tell, but I would be surprised if a "lepracutta" turns out to be fertile. Galapagos tortoise hybrids may be thought of as merely mutts; it's the kinds of hybrids you find in the pet trade that may be likened to mules.

"Well, remember, Galapagos tortoises are all very closely related to each other ... at the subspecies level, like different types of box turtles. Again, this is a far cry from the relationship between sulcatas and leopard tortoises, which are at least in different species, if not in different genera."

Even though being from the same Continent for 1,000's of years?

"Time will tell, but I would be surprised if a "lepracutta" turns out to be fertile."

Like Mentioned before I dont have really interest if they will be . Iam more interested in absorbing info , and seeing it " first hand" , plus the fact it was possible . If they are so distant from one another I doubt any of the eggs would have been fertile at all ...no? If there are no boundaries within a genetic link then we should be able to cross a Leo with a radi' , Or an yellow foot and a Russian right?
Sullies and Leos are both Old World tortoise's that have evolved from at least one species , before the " so called boundry line" split ?

 

[cdmay]

Why would they have to sterilize Hybrids if " they are mules" as some folks think ?

As GeoTerraTestudo (GTT) has explained, the issue isn't as simple as 'some folks think'. Not all mixed breedings result in sterile offspring-- and that is the problem. The point isn't at all whether or not two distinct populations might produce fertile offspring if crossed together. Heck, captive breeders have forced all kinds of unnatural crosses that have resulted in fertile offspring. So what? All that means is that the old, 'hybrids are all sterile' belief was wrong. The real issue is that unique and distinctive populations will become polluted as a result all of this crossbreeding, hybridizing or whatever you call it.
Added to this threat is the undeniable track record of reptile breeders in general who, in just a couple of decades, have completely ruined most of the captive populations of Boa constrictors, corn snakes, kingsnakes and so many other reptiles that they 'work with'. Just try and find a captive produced Boa constrictor or corn snake that doesn't possess numerous mutations or genes from multiple unique wild populations in its DNA. It's nearly impossible because of all the mixed breeding and wanton crossing just to spread albino and other mutant genes...all for the sake of making a quick buck. Now all of these captive animals are genetically tainted thanks to those numbskulls.
The Galapagos tortoises that are of mixed heritage that are being released onto Pinta Island by the CDRC have been sterilized for good reason. Those people know what they are doing and realize that the tortoise populations have been screwed up enough. Incidentally, the tortoises are being released on Pinta because the lack of the island's large but slow moving herbivore--the extinct Pinta tortoise-- has disrupted the native plant systems. It is hoped that the released 'mutts' will at least serve some useful purpose by restoring that balance.

 

[N2TORTS]

I was waiting for you to pip in ....
excellent info Carl~
"As GeoTerraTestudo (GTT) has explained, the issue isn't as simple as 'some folks think'. Not all mixed breedings result in sterile offspring".....
Coming from YOU and GTT theres proof right there about alot of assumptions and misbeliefs that hybrids are mules right ?


Also isn't it true that ......Sullies and Leos are both Old World tortoise's that have evolved from at least one species , before the " so called boundry line" split.... correct?


I find these threads interesting and peoples views about genetics and the " naming of species" of animals we discover in current times.
Thanks for the opinion.

JD

 

[cdmay]

I was waiting for you to pip in ....
excellent info Carl~
"As GeoTerraTestudo (GTT) has explained, the issue isn't as simple as 'some folks think'. Not all mixed breedings result in sterile offspring".....
Coming from YOU and GTT theres proof right there about alot of assumptions and misbeliefs that hybrids are mules right ?

Hybrids of higher animals (the example of lions crossed with tigers and then actual mules has already been discussed) usually are sterile.
Reptiles and other 'lower' life forms are different. So very often hybrid reptiles are not sterile. But that doesn't in any way mean that is is OK to start producing hybrids. If anything, it makes the intentional production of hybrids even more irresponsible and reckless.

Also isn't it true that ......Sullies and Leos are both Old World tortoise's that have evolved from at least one species , before the " so called boundry line" split.... correct?

They may have come from a common ancestor but so what? That was eons ago and now they are clearly very different animals. Why muddy the limited genetic waters by using the common ancestor excuse? A hybrid tortoise can live a very long time and may pass from one owner to several others over its lifetime. Who is going to insure that it won't be bred by someone who doesn't realize it is a hybrid?
Can you see the potential problems? That is why the CDRC took the drastic measure of sterilizing those mixed Galapagos animals--they knew the risk was too great to allow populations that are already in grave danger to become genetically crossed up.

I find these threads interesting and peoples views about genetics and the " naming of species" of animals we discover in current times.
Thanks for the opinion.

You make a good point when you imply that the 'naming of species' is a recent event. I agree in that the whole taxonomy issue can be a mess and needs work. But I would still counter that taking animals that do not intergrade in nature, (or that live sympatrically without interbreeding) and intentionally creating hybrids from them is largely foolish and irresponsible.

 

[GeoTerraTestudo]

Well, remember, Galapagos tortoises are all very closely related to each other ... at the subspecies level, like different types of box turtles. Again, this is a far cry from the relationship between sulcatas and leopard tortoises, which are at least in different species, if not in different genera.

Even though being from the same Continent for 1,000's of years?

That's correct. Populations drift apart whenever there is some barrier to gene flow, and that could be a river, a forest, a mountain range, a strait, whatever. This is how the different types of Galapagos tortoises have evolved in different directions; each one has its own island, and no longer interbreeds with animals on other islands. Same thing for box turtles. A continent is a big place, and there are big latitudinal differences in climate. Eastern box turtles deal with different conditions than three-toed, Gulf coast, and Florida box turtles. Also, each box turtle has a home range of only an acre or two, so they do not travel very far in a lifetime. This means that over time, genetic differences will accumulate between populations, eventually resulting in subspecies. If the process continues for a longer period, and/or if there are big enough environmental differences, then you can even get speciation. This is why there are four different species of box turtle in North America (Terrapene carolina, T. ornata, T. coahuila, and T. nelsoni), and even more subspecies.

---

Like Mentioned before I dont have really interest if they will be . Iam more interested in absorbing info , and seeing it " first hand" , plus the fact it was possible . If they are so distant from one another I doubt any of the eggs would have been fertile at all ...no? If there are no boundaries within a genetic link then we should be able to cross a Leo with a radi' , Or an yellow foot and a Russian right?
Sullies and Leos are both Old World tortoise's that have evolved from at least one species , before the " so called boundry line" split ?

Well, the differences may be such that a mating can produce a hybrid that is viable, but not fertile. Again, mules are very healthy creatures, but they are almost always sterile. A little closer than that are wolf-coyote hybrids, which have reduced fertility, but are not completely sterile. Closer still are wolf-dog hybrids, which are completely fertile (as dogs are considered domestic wolves). Go farther out than mule distance, and you find animals that are not only sterile, but don't even survive: like hybrids of African and Asian elephants, for example, which die as babies. Any farther out than that, and the embryo doesn't even survive long enough to be born.

So, it is apparent that sulcatas and leopard tortoises are close enough to form viable hybrids, but that does not necessarily mean that they can form fertile hybrids.

---

They may have come from a common ancestor but so what? That was eons ago and now they are clearly very different animals. Why muddy the limited genetic waters by using the common ancestor excuse? A hybrid tortoise can live a very long time and may pass from one owner to several others over its lifetime. Who is going to insure that it won't be bred by someone who doesn't realize it is a hybrid? Can you see the potential problems? That is why the CDRC took the drastic measure of sterilizing those mixed Galapagos animals--they knew the risk was too great to allow populations that are already in grave danger to become genetically crossed up ...

You make a good point when you imply that the 'naming of species' is a recent event. I agree in that the whole taxonomy issue can be a mess and needs work. But I would still counter that taking animals that do not intergrade in nature, (or that live sympatrically without interbreeding) and intentionally creating hybrids from them is largely foolish and irresponsible.

Good posts. Do you think there is an ethical way to discourage reptile breeders from creating hybrids? I mean, on the one hand, the animals belong to them, and it would be paternalistic to tell them what to do with their own animals. On the other hand, as you've explained, they are damaging the gene pools of captive reptiles. So what can be done? Do you think people would think twice about making hybrids if they knew the consequences of those actions? Would educating people help them make informed choices? The choice would still be theirs, but maybe some of them would elect not to breed hybrids after all.

 

[Neltharion]

I was waiting for you to pip in ....
excellent info Carl~
"As GeoTerraTestudo (GTT) has explained, the issue isn't as simple as 'some folks think'. Not all mixed breedings result in sterile offspring".....
Coming from YOU and GTT theres proof right there about alot of assumptions and misbeliefs that hybrids are mules right ?

I wouldn't say that there are assumptions or misbeliefs. A better characterization would be to say that there are generally accepted truths to hybrids with rare existing exceptions. Most hybrids are sterile, that is true. On rare occasions, you will get hybrids that can reproduce. In the mule example, male mules are known to be sterile. On rare occasions females are fertile. Even among the parrot cichlids and flowerhorns, on rare occasions some of those hybrid fish are found to be fertile and capable of reproducing.

Also isn't it true that ......Sullies and Leos are both Old World tortoise's that have evolved from at least one species , before the " so called boundry line" split.... correct?

Keep in mind that Africa is a continent that expands across roughly 11,700,000 square miles. Where a sulcata's native range is the Sahara and the Sahel, and a Leo's range are the south eastern savannahs around Sudan down to the Cape. That's a huge gap that these tortoises have evolved across.

While you may consider then closely related because they evolved from a common ancestor. As a point of reference, we Homo sapiens and the common chimpanzee Pan troglodytes, have DNA that is 96 to 98% identical. Yet people would affirmatively say the differences are huge.

I find these threads interesting and peoples views about genetics and the " naming of species" of animals we discover in current times.
Thanks for the opinion.

One thing is that Linnaeus started taxonomy and the naming of species back in 1735. Its been around and dare I say 'evolved' over close to 300 years. Certainly not anything done just in current times.

---

Good posts. Do you think there is an ethical way to discourage reptile breeders from creating hybrids? I mean, on the one hand, the animals belong to them, and it would be paternalistic to tell them what to do with their own animals. On the other hand, as you've explained, they are damaging the gene pools of captive reptiles. So what can be done? Do you think people would think twice about making hybrids if they knew the consequences of those actions? Would educating people help them make informed choices? The choice would still be theirs, but maybe some of them would elect not to breed hybrids after all.

At least among the fishkeeping communities, particularly those that keep African or Central/South American cichlids, they discourage people from cross breeding and buying hybrids. They tell keepers, if you must cross breed fish, keep them to yourself, not to sell them and not to give them away.

I know for reptiles the situation is a little different. Since not everyone necessarily has the space to keep all of the offspring they produce. I seem to remember this topic came up in another thread too.

As many of these less-developed countries encroach on the natural habitats for housing and other development, some cultures capture these reptiles for food, and poachers capture endangered species for the underground pet trade, there will come a point in time where the last existing populations of many of these animals will be in captivity. As hobbyists, I would argue that we have a responsibility to keep these bloodlines pure. Someday there may be breeding and release programs to try to re-establish some of these species back into the wild (I can think of the Galápagos Pink Land Iguana as an example).

 

[cdmay]

They may have come from a common ancestor but so what? That was eons ago and now they are clearly very different animals. Why muddy the limited genetic waters by using the common ancestor excuse? A hybrid tortoise can live a very long time and may pass from one owner to several others over its lifetime. Who is going to insure that it won't be bred by someone who doesn't realize it is a hybrid? Can you see the potential problems? That is why the CDRC took the drastic measure of sterilizing those mixed Galapagos animals--they knew the risk was too great to allow populations that are already in grave danger to become genetically crossed up ...

You make a good point when you imply that the 'naming of species' is a recent event. I agree in that the whole taxonomy issue can be a mess and needs work. But I would still counter that taking animals that do not intergrade in nature, (or that live sympatrically without interbreeding) and intentionally creating hybrids from them is largely foolish and irresponsible.

Good posts. Do you think there is an ethical way to discourage reptile breeders from creating hybrids? I mean, on the one hand, the animals belong to them, and it would be paternalistic to tell them what to do with their own animals. On the other hand, as you've explained, they are damaging the gene pools of captive reptiles. So what can be done? Do you think people would think twice about making hybrids if they knew the consequences of those actions? Would educating people help them make informed choices? The choice would still be theirs, but maybe some of them would elect not to breed hybrids after all.

Hybridizing, in of itself, is not necessarily the issue or the problem. The problem lies in what people do with those hybrids.
For example, N2TORTS has a hybrid tortoise that is a cross between a leopard tortoise and a sulcata-- OK fine. It is probably an interesting animal to maintain too and I can understand JD being excited about growing it up. So then the pressure is on JD to be a responsible keeper who maintains good records and steadfastly keeps that animal from reproducing for all of the reasons that have been mentioned above.
But suppose there are bunches of those hybrids floating around that get sold to irresponsible keepers who feel that it is within their rights to breed it to whatever they want? What about that first buffoon who hits on the grand idea of crossing a leopard tortoise with an 'ivory' or amelanistic sulcata just to eventually come up with ivory or albino leopard tortoises? Don't laugh--this is exactly how there are now all kinds of hybrid albino Boa constrictors that stemmed from a couple of Colombian animals that uneducated breeders then bred to Peruvian, Surinam, Guyana and every other distinct type of Boa constrictor. Now the entire captive gene pool of Boa constrictors consists mostly of mutts.
What is the long term outcome for the tortoises...besides a colossally screwed up captive gene pool, I mean? As this is already the case with many captive hatched reptiles I sure do not have faith in the captive breeders.
Ideally, reptile breeders would have been like orchid breeders who maintain very, very detailed records of every registered cross between known orchid species. I think that the American Orchid Society (AOS) even has a database that can be accessed to see just what parentage is involved with each new hybrid. In addition, orchid growers have religiously maintained pure species and subspecies, as well as regional variants for many generations and so there is little danger of them becoming lost to future generations. Also, orchids can now be cloned through tissue culture which also aids is preserving pure species for the future.
Sadly, reptile keepers have demonstrated that very often ego and greed are the driving intrests when it comes to reptile husbandry and it all becomes about the $$.

 

[dmmj]

Reptile keepers have egos? I am shocked.

 

[N2TORTS]

Carl ...and GTT ... thanks for all the valuable info , and the time to share with everyone , including me. Once again I did not breed these myself ( not that it matters) , but simply a trade I made 2 years back for a fresh insight for myself with a breed/hybrid ( or whatever ya wanna call it ) that I have never worked with or owned. I have no intentions actually on breeding them at this point that would be years down the line anyhow, but along with all my torts, keeping very accurate records and watching visual changes as they develope. Thus far, I must say they are both really neat lil' torts with tons of personality , very active , healthy and happy.
I myself enjoy the time spent with them too~
Also as long as the debates are civil I think they are an important part of learning from each other , as we all have had different educations/ life experiences and opinions that just adds to the " Great Book Of Knowledge"
JD~

 

[cdmay]

Carl ...and GTT ... thanks for all the valuable info , and the time to share with everyone , including me. Once again I did not breed these myself ( not that it matters) , but simply a trade I made 2 years back for a fresh insight for myself with a breed/hybrid ( or whatever ya wanna call it ) that I have never worked with or owned. I have no intentions actually on breeding them at this point that would be years down the line anyhow, but along with all my torts, keeping very accurate records and watching visual changes as they develope. Thus far, I must say they are both really neat lil' torts with tons of personality , very active , healthy and happy.
I myself enjoy the time spent with them too~
Also as long as the debates are civil I think they are an important part of learning from each other , as we all have had different educations/ life experiences and opinions that just adds to the " Great Book Of Knowledge"
JD~

That is a neat looking animal that should become a very interesting adult... I would just hate to see a lot of them getting spread around.

 

[wildak]

I can see benefits to cross breeding . Learning what species can cross and reproduce could save species in the very near future.
If there's only a handfull of a type of tortoise you could then cross it to another species and after several generations and many years later have a whole new bloodline that's a 100% pure blood.
If you have one extremely rare male tortoise you could possibly breed it to an endless amount of females of another species. Like Lonesome George, they have been attempting to get him to breed to save his genes. If he breeds we could save his species.

Heck I heard talk of cloning a Mammoth from recently found viable dna in the ice. They would cross it with an African Elephant and after many generations could have a 100% pure Mammoth. Now that's some crazy #%@#. Though it is thought that mankind is the reason they went extinct. So should we do it to fix what we screwed up ?

 

[GeoTerraTestudo]

I can see benefits to cross breeding . Learning what species can cross and reproduce could save species in the very near future.
If there's only a handfull of a type of tortoise you could then cross it to another species and after several generations and many years later have a whole new bloodline that's a 100% pure blood.
If you have one extremely rare male tortoise you could possibly breed it to an endless amount of females of another species. Like Lonesome George, they have been attempting to get him to breed to save his genes. If he breeds we could save his species.

Heck I heard talk of cloning a Mammoth from recently found viable dna in the ice. They would cross it with an African Elephant and after many generations could have a 100% pure Mammoth. Now that's some crazy #%@#. Though it is thought that mankind is the reason they went extinct. So should we do it to fix what we screwed up ?

Re: hybrids and conservation
I think that, because Lonesome George is literally the last of his subspecies of Galapagos tortoise, we should allow him to hybridize with another Galapagos tortoise subspecies, provided that those progeny are treated as the new representatives of his kind, and not his mate's kind, meaning that they are not allowed to interbreed with other subspecies of Galapagos tortoises. It would be easier if the last of a race is female, since then the male from another subspecies would still be available for his own kind, but that is not the case. An inter-generic hybrid like a lepracutta would have to be a really desperate attempt at conservation, like if there were only one sulcata and one leopard tortoise left in the whole world (which is, thankfully, not at all the case). Other than such last ditch efforts as these, there's really no reason for it. And as I've said, it can actually interfere with conservation efforts because you can't release hybrids back into the wild, partly because they will created "genetic pollution" with existing full-blooded animals, and partly because they might not be as well adapted to the environment as either parent species.

Re: cloning and rewilding
I'm all for cloning mammoths (even though it's a long shot, at best) because, as you say, they probably went extinct due to over-hunting by humans in the first place. I am generally a proponent of the "you broke it, you bought it" approach to restoration. If animals have become endangered due to human activities, then it's up to us to help them. And if they have become extinct, then assuming we have the technology, we should try to bring them back. I am also a proponent of introducing closely related animals from other areas if and only if the native subspecies is extinct. Again, if we caused the damage, then we should try to repair it. Otherwise, not only is it none of our business, but it would actually be meddling for us to try to change things that came about independently of our actions.

 

[wildak]

I totally understand where your coming from GEO and agree that hybrids must never be allowed back to the wild, in fact they should be put down first.
That being said I think we should explore the idea of crossing extremely rare turtles and tortoises in order to see if the hybrids are sterile or not and to have future genetic lines. It would have to be done with conservation in mind and not pet trade. Possibly a hybrid microchip plan could help identify % of genetics in the case of human error.
I just think if we don't explore the idea until there's a natural or man made disaster certain species could be S.O.L. since some species are limited in captivity.
Food for thought.

 

[Doritoinmontucky]

It is good for people to have a place to express there views without verbal abuse, or put downs. I believe that Hybrids should not be sought after, but the fact that spieces dieing out should raise some attention to the fact that we should have some more programs for there conservation. Methods of Hybriding could unlock questions that scientists have. But i bieleve it should be done in a controlled enviorment.

-Derrik