What are everyone's opinions on subspecies conservation in zoo populations - specifically, in already threatened or endangered species? This is something that interests me, and I don't intend to go against the tide if this view is not shared, but I think that that preserving every living endangered subspecies (in this example I think particularly of tigers) in isolation from one another is an arbitrary method of management that follows the false idea that nature must be preserved exactly as it is now, today, in the time we are currently living - when really life is in a constant state of genetic flux and has been since the beginning of life on Earth. It limits genetic diversity, particularly for those subspecies with very small captive populations (Sumatran tiger) - if Sumatrans are only bred to Sumatrans there are only going to be so many unrelated pairings possible before every living cat is a relative. This sounds like a recipe for problems. Is it really better to keep populations, such as the Sumatran, Bengal, and Amur tigers, in reproductive isolation - at the risk of at least one of those subspecies possibly becoming weaker and more inbred? Why should they not be managed as a single much more diverse population - just tigers? Assuming that the difference between them is not so much as to result in outbreeding depression (as far as I know, not documented in tigers or lions) is this mixing of genes really a loss, or can it be a gain? I have seen mentions many times of zoo-mix lions and Bengal tigers with Amur genes and how these animals are useless for conservation and all I can think is... why is this so? They are still lions and tigers, and if ever there was a time where we were going to reintroduce either species into the wild, a generic member of either species should carry all the genes of its predecessors and populations would be selected again into new races or subspecies in a relatively short time just as the ancestral, generic lion or tiger did, right? The ecosystem of the future won't care if the lion on the plains has distant Asiatic ancestors, or if the Indian tiger had a great-grand-grandparent from Siberia, if it only needs a large predator to control herbivore numbers. It can be argued that pure subspecies are perfectly adapted to their specific region of origin, and this is true. The Sumatran tiger is small and adapted to the humid tropics, the Amur large and suited to boreal winters. But they are adapted to a world that is rapidly changing, to habitats that may soon no longer exist. In the best case scenario, the tigers of the future will not live in the world of their ancestors. Evolution demonstrates that in changing conditions, it is the generalist that survives, not the specialist. Furthermore, at least as much of an influence on the adaptability of the animal seems to come from its environment as its genes; even the purest Amur tiger from the average zoo environment today would fail to hunt a boar or a moose without being taught by a competent mother tiger - a Sumatran cub, if fostered to a wild Amur mother would stand a greater chance. The Siberian's fur is thicker, but the Sumatran's also thickens in a cold climate, and the reverse is true for an Amur in a tropical area. I strongly suspect that either subspecies, lying at the extremes of size as they do, could survive over almost the entire range as all of the modern and recently extinct tiger subspecies did if they were somehow properly acclimated to local climate and prey. Granted, teaching hunting and self-sufficiency is a huge hurdle with any captive carnivore, but it would not be inherently simpler to teach a Sumatran tiger to hunt Sambar than to hunt sika. There is no genetic component to managing the specific prey of a given region and all must be learned anyway. I know that Asian elephants in the United States are managed at species level due to the low population, but I think that there are other species which have already reached low enough levels that subspecific conservation should be abandoned. I would consider tigers among them, and I would also consider lions - though this really isn't a problem anymore considering that the majority of the lions in captivity are already mixed it does seem totally incorrect to label this whole population as useless to conservation just because they are not pedigreed. I would not currently condone releasing African genes into the Gir forest population at this time because that group is already beyond the carrying capacity of its environment, though the influx of genes would certainly benefit the population which right now is heavily inbred. However, if somehow, someway, space opened up to introduce lions somewhere else in Asia I would absolutely condone introducing a more vigorous generic zoo-mix group versus trying to spread the Asiatic remnants further. A few generations in the wild would already begin producing a new uniquely adapted land race, adapted not for a habitat of the past, but whatever habitats the future offers. Humans have drastically changed the world and the areas all of these animals come from, yet we are very determined to make sure the animals stay exactly the same as they were at the exact point of time we started to classify them. This goes against how nature operates, where there are no constants, no species, simply constant and relentless genetic change. I feel the same about the wolf coyote complex between the coyote and the gray, Eastern, and red wolf. I feel we shouldn't be preserving the red wolf, it was an animal that evolved in a previous world, a world without man and arbitrary species borders, and it will not survive in a pure form today without human influence. But it can interbreed with the gray wolf and the coyote, and in a wild setting, some of their genes would go on, and the Canis genus as a whole would persist and rediversify as it has surely many times for hundreds of thousands of years. I don't know enough about orangutans to make a judgment. The Bornean and Sumatran are now known to be genetically distinct, but how distinct are they? They are clearly cross fertile as dozens of zoo hybrids show, but whether out-breeding depression would develop as they in turn were bred unfortunately, we don't definitively know. If F2, F3 and further hybrid crosses proved to be prone to infertility or defect, I'd say halting the hybridization when we did was indeed the right thing. But I have to wonder if, given the dire state of the orangutan genus in the wild and the overall still rather small zoo populations, if allowing the two variations to merge to a single hybrid population would have improved their chances of long-term survival. Hybrid speciation is a documented occurrence, and is currently occurring with the gray wolf and coyote in the Eastern US and Galapagos finches. Note, I am not condoning the automatic disregard for genetic diversity - if it were feasible to preserve ten varieties of something in captivity and the habitats each came from remain in the wild to reintroduce them back to, it would be wonderful. But this isn't the case with most large, endangered animals - tigers, Asian elephants, red wolves or orangutans. Zoos have limited space, and we almost certainly do not have the means to maintain healthy isolated populations of three tiger subspecies indefinitely without compromising the health of at least one (and with most of the captive Bengal population impure, this would leave us only with a small pure population of Amur tigers - each carrying but a fraction of the former diverse genes of the species) Our Ark is finite in capacity, and the wild habitats these animals came from may not be there when the time may come to let some animals go back to it anyway. That is my view, anyway.
If the UK and Japan were ever serious about reintroducing the “wolf” to Scotland or Hokkaido, I believe the Red Wolf would be a perfect species to replace the island races lost to extinction. The lack of Coyotes, Golden Jackels, and Grey Wolves cabable of naturally colonizing the Red Wolves’ new territories would ensure the species carried on into the future. It would also ensure that the islands received a sustainable population of midsized candid capable of living near human civilization and able recreate the ecological role of the previous wolf species. In my opinion, wins all around....
I agree. That is turning into rewilding territory though, which is a whole 'nother can of worms. I think it's great, but not everyone does.
I agree in principle with Sheather. Colin Tudge wrote "A tiger is a tiger is a tiger" and I doubt if most zoo visitors are bothered about whether a tiger belongs to a specific subspecies. As there only seems to be one scheme to train captive tigers to adapt to life in the wild, the purpose of keeping pure subspecies in captivity is dubious, especially as there are several smaller endangered species of carnivores that could be kept and bred in zoos and be used to replenish wild stock. It would be better to conserve tiger subspecies in the wild. I used Zootierliste to compile the following list, which compares zoos keeping different types of tigers with those keeping different species of other cats: 390: Lion, Northern lynx 226: Leopard 190: Siberian tiger 170: Wild cat 158: Tiger (subspecies not listed) 133: Cheetah 128: Serval 111: Jaguar 102: Puma 100: Snow leopard 64: Caracal 60: Ocelot 59: Sumatran tiger 45: Fishing cat 41: Clouded leopard 40: Pallas’s cat 36: Leopard cat 32: Jungle cat 31: Geoffroy’s cat 29: Jaguarundi 25: Sand cat 22: Bobcat 16: Margay 14: Rusty-spotted cat 9: Malayan tiger, Canadian lynx 7: Asiatic golden cat 6: Oncilla 4: Iberian lynx This indicates that many zoos keep tigers, but a large percentage of these do not seem to belong to a given subspecies. I doubt if many visitors are that bothered. The following list is of tiger subspecies and cat species formerly kept in zoos listed by Zootierliste: 100: Bengal tiger 25: Black-footed cat 12: Marbled cat, Javan tiger 11: Indochinese tiger 10: African golden cat 9: Pampas cat 6: Caspian tiger 5: Flat-headed cat, Sunda clouded leopard 3: Andean mountain cat, Chinese mountain cat, Kodkod 1: Bornean bay cat I would much prefer to see some of the cats in this list rather than visiting another tiger enclosure.
So I understand your point that hybridizing certain subspecies can increase the genetic diversity of the population as a whole but it's not as simple as you put it. Just hybridizing does not guarantee the offspring will carry the advantageous genes that each subspecies evolved over thousands or millions of years of separation. There is still a lot that scientists do not know about in terms of genetic advantages. How do we know that a Sumatran-Amur tiger hybrid will be suited for both environments? There is an equal chance that the hybrid is less adapted for both environments than either of the purebred subspecies. In terms of tigers in zoos, we are actually very lucky to have distinct subspecies in manageable groups. It allows us to keep the subspecies pure in case there is an opportunity for release. This is different than the African lion population which was already very mixed before a management system could be implemented. Another point you made was that all these environments need are large carnivores to control prey species. This is really simplistic and it ignores the specific adaptations needed to survive in the many varied environments. Just because Sumatran and Amur tigers are large predators doesn't mean that is all they need to do to survive. They need to be adapted to the specific prey items that live in those environments, the climates, where water can be found, etc. What hybridizing could potentially do is lose these adaptations for specific environments and make a "jack of all trades, master of none" group of animals that may potentially survive in any environment, but there is also a major chance that they will not thrive. This is because of processes like genetic drift may cause the elimination of traits that allow the specific subspecies to survive just by random chance. So until we understand how the adaptations are controlled by genetics, it is reckless to try and play god by making hybrids. Hybrids aren't always "super" versions of the animals. Often they lose traits that one or both subspecies needs to survive in their environments. We also can't just introduce a species or subspecies into an environment that it was never adapted to. Not only could this be bad for the species, but history has shown that unintended consequences occur frequently for the environment when animals are introduced (Cane toads, mongoose, etc.). They are great ideas but they often end up poorly when attempted. As for your example of orangutans, they are now known to be distinct species, not subspecies and there are many behavioral and physical differences between them that add to the genetic differences that caused them to be separated. As we learn more, we are very likely to find similar differences in tigers subspecies that may cause them to be further separated into species. So for now, zoological institutions are playing it safe and avoiding hybridizing because the chance of unintended consequences are too high. If there is a chance to keep subspecies distinct, it is smarter to do that. For many species in captivity it's too late though and the goal is to now keep the mixed population as diverse as possible.
You make fair points but in regard to these points, I think these are not genetically inherited inclinations. A tiger has some instinctive motor patterns to hunt large ungulates, but whatever it is hunting, it has to learn to hunt regardless of its genes. A Sumatran tiger certainly isn't born knowing where to find water in the rainforest and an Amur in the boreal forest! Climate is possibly a concern, the subspecies are notably adapted to very different ones, but I am not convinced the differences are so severe as to totally inhibit a hybrid from adapting to either if raised in situ/trained to survive in the local environment before release. Right now I think we're okay continuing to separate the tiger subspecies (I would hesitate to ever regard them as species but I am a lumper) but if the time ever comes where one or more pure lines begins to experience a serious loss of vigor I would hope to see hybridization occur rather than the total loss of genetic diversity. There was opposition to introducing Texas mountain lions into the Florida panther range but the result was healthier cats. In an ideal world we could keep everything separate but we're already playing God on an unimaginable scale in regards to destroying biodiversity. I don't necessarily see anything wrong with doing it further in an effort to try and improve the odds of some of it. Cane toads in Australia and mongooses, rats, pigs and cats on islands are bad examples because they involve island wildlife which had never previously had such animals (predators and highly toxic toads which eat everything) to evolve to deal with whereas all across Europe, Asia, and North America there were very large predators until comparably very recently until we exterminated some and pushed the others into little pockets. Big cats are not the only examples, just the one that first came to mind, as tigers are so large and they take up a lot of space and zoo resources. If space is limited, and it is, I'd rather have one tiger and several other animals we'd otherwise maybe lose.
I think this would be good if it were not for rising human populations and decreasing natural habitats. It would be very difficult to introduce captive tigers into the wild, even if there were adequate habitat. Increasingly, such tigers would be more likely to feed on people and their livestock, rather than other prey. I agree with the last paragraph. I would prefer zoos to try and conserve as many species as possible, rather than pretending that having the same species in many zoos is conservation, even though many large species are not used to replenish wild populations. Many zoos are involved with protecting large animals in the wild, which is more important to help save animals and natural habitats than spending millions on expensive enclosures and implying that the only species that need to be saved are those that are popular with the general public.
The former wolf population in the UK were, I believe, not all that different in size to the extant C. lupus lupus - and may well have belonged to that taxon - and as such were not really comparable to Red Wolf, nor either of the extinct island races of Japan.
I know. My thought on the subject is that the isolated population (6,000 years or more removed from the genetic influence the continental populations) of Eurasian Wolf on each island is extinct. The exact genetic (sub)species is not recoverable. A suitable, conservation dependent, morphological, and ecologically comparable species is....ergo....humans are themselves a geological event...overtime geological events enable species to colonize new habitats...speciazation is a continuous and natural process...Red Wolves of Scotland. I do believe that the reflexive “purist” response to “invasive species” (on continental land masses) is akin (philosophically) to the “we have to subdue nature to our purpose” response local folks have to the appearance of large carnivores into areas where they have not previously been common... Just my opinion.
Except that, as already noted, the UK population of wolves was neither morphologically or ecologically comparable to the Red Wolf and the native subspecies is likely to still exist, even if the exact genetic subpopulation does not. To draw a comparison from the bird world, the UK population of White-tailed Sea Eagle was extirpated in 1914; when reintroduction programmes took place the birds in question were taken from the Norwegian population, and they didn't even consider bringing over Bald Eagles from the New World.
You are right. I would just point out (strictly from a fanatastical...maybe even romantic conservation philosophy) that the Eurasian Wolf is secure in Europe. Scotland (and Hokkaido) don’t necessarily need those wolves to have wolves....whilst the Red Wolf desperately needs to have a secure (and isolated from other canids) habitat if it is going to avoid being absorbed into the Coyote population...although it will leave it’s mark in the form of subtly changed Coyotes....and really the ebb and flow of species...me being a lumper anyway....is the passing of the Red Wolf as a distinct population, biologically speaking...really that tragic? Maybe in wanting Japan and Britain to host and save America’s Wolf....I’m the purist...unreasonablly and dogmatically interfering with the natural process.
Of course, when it comes to the two lost Japanese subspecies it's worth noting that they were not particularly close kin, nor similar to one another in morphology - as I understand it the Hokkaido Wolf was actually found within the Kamchatka peninsula too, was a relatively recent arrival to Japan and represented a sister taxon to Canis lupus occidentalis, whilst the Honshu Wolf was a much more basal subspecies whose closest kin are the Italian Wolf and Iberian Wolf. As such, the Red Wolf would be a much better substitute for the latter than it would the former.
In regard to tigers, while I do agree with the principle, I feel it may be really easy to mess up the procedure. I feel that cross breeding an Amur tiger with a tropical tiger may not be the best. In Russia, I assume these tigers will need to be big to hunt and survive. Cross breeding a Malayan with a Sumatran could probably be ok, however, you will need to maintain either a high amount of Sumatran or a high amount of Malayan DNA to keep somewhat distinct species. Disclaimer: I am not a geneticist and would love to hear your thoughts
I think you have misunderstood Sheather's original statement, which was to reduce the number of captive tigers. If Amur tigers were being kept in captivity to be released into the wild, there would be a problem with cross-breeding captives with smaller subspecies. Tigers are being kept to attract visitors, most of whom are probably not bothered about the subspecies and would probably prefer to see white tigers. There are too many endangered species that do not have captive populations and the idea of keeping pure subspecies is a luxury when wild habitats and their fauna are being continually destroyed.
Precisely, though if all tiger phenotypes were mixed, the resulting generic population would probably be most like the Bengal (as it's the most common tiger) on the medium-to-large spectrum, and probably could adapt to many conditions, like the ancestral tiger.
The biggest issue is that subspecies of most animals were defined before genetic research became common, and often decades ago using very little data. So subspecies are usually a mess. Often, decades-old classification is repeated again and again, with nobody checking that it is very bad. Zoos try to follow 'official' designation, which may not be right. Even species are often confused, like zoos finding themselves with hybrid Yellow-breasted capuchins and mandrill/drills. Besides, zoos can do anything they wish. However hybrid subspecies are useless for conservation, except as conservation ambassadors. Exception are very few cases where the 'pure' form is already extinct (like northern white rhino, Pinta giant tortoise, Barbary lion and lowland-mountain Wisents). Zoos otherwise will never get permission to reintroduce hybrid animals.
Concerning the Tiger: it is so popular in zoos that sufficient space exists to keep sustainable population of every subspecies separately. Absolutely no need to combine subspecies from zoos point of view. Unless conservation in the wild fails again, like it let last few Javan tiger die in the wild rather than be bred in zoos. The same would be true for example for lion, giraffe, asian elephant or chimpanzee.
