"Have you been watching Tiger King?"
Several of my friends have asked me about the newest Netflix sensation, which explores a small section of the underbelly of exotic animal trade and private zoos in the USA.
I hadn't before. Now I have. I feel dirty.
The sad thing is, although the traders and keepers shown in the series are sensationalised, they're not unusual. The world is full of mentally tortured people who collect exotic species and strong opinions. Giving them air time doesn't really help the animals in their care; legislation and enforcement does.
Now that we've got that out of the way, the most interesting part of watching poorly-bred big cats prowl around the screen was all the weird and wacky genetic combinations that have popped up along the way. Here are the ones I spotted, and a little information about them. Note that breeding these poor beasts has about as much to do with conservation as planting magnolia trees in your backyard has to do with saving the rainforest.
Several of my friends have asked me about the newest Netflix sensation, which explores a small section of the underbelly of exotic animal trade and private zoos in the USA.
I hadn't before. Now I have. I feel dirty.
The sad thing is, although the traders and keepers shown in the series are sensationalised, they're not unusual. The world is full of mentally tortured people who collect exotic species and strong opinions. Giving them air time doesn't really help the animals in their care; legislation and enforcement does.
Now that we've got that out of the way, the most interesting part of watching poorly-bred big cats prowl around the screen was all the weird and wacky genetic combinations that have popped up along the way. Here are the ones I spotted, and a little information about them. Note that breeding these poor beasts has about as much to do with conservation as planting magnolia trees in your backyard has to do with saving the rainforest.
1: White Tiger
Contrary to popular belief, white tigers are not their own species, and they're not Siberian either. They are just mutant Bengal tigers. The white coat is the result of a recessive mutation in the SLC45A2 gene, so two wild-type* tigers can be carrying the mutation and have a white cub. The SLC45A2 gene is also part of colour determination in animals such as horses and chickens.
White tigers have occasionally been found in the wild throughout history, and the fact that many have grown to adulthood suggests that the mutation does not appear to be harmful. However, only a handful have ever been captured for captivity. Yet white tigers are common in collections today.
Unfortunately, captive white tigers are largely produced by inbreeding. The novelty of unusual colouration has drawn crowds since the 1950s, when a male white tiger was caught and bred to his offspring. White tigers in captivity today are descended from very few wild individuals (possibly only one). Such inbreeding has led to genetic defects such as stillbirths, weakened immune systems, premature death, and deformities such as cross-eyes and twisted necks.
White tigers have occasionally been found in the wild throughout history, and the fact that many have grown to adulthood suggests that the mutation does not appear to be harmful. However, only a handful have ever been captured for captivity. Yet white tigers are common in collections today.
Unfortunately, captive white tigers are largely produced by inbreeding. The novelty of unusual colouration has drawn crowds since the 1950s, when a male white tiger was caught and bred to his offspring. White tigers in captivity today are descended from very few wild individuals (possibly only one). Such inbreeding has led to genetic defects such as stillbirths, weakened immune systems, premature death, and deformities such as cross-eyes and twisted necks.
2: Golden Tiger
As I said above, sometimes white tigers just aren't enough to wow the public. So what do you do to mix it up a bit? You breed inbred tigers together and you end up with a pale brown stripey cat with a lot of white on it. A bit like a pet cat really. But this one has a fancy name - a GOLDEN tiger. Need I point out that wild-type tigers are pretty golden as well?
The golden tiger has a recessive mutation in a different gene. The mutation is known as "Wideband", referring to its effects on a wide part of the hair shaft.
In 2014, a golden tigress was camera-trapped in the Kaziranga National Park, India. Rather than celebrating the presence of a golden tiger, the staff at the Kaziranga National Park saw it as evidence of inbreeding in their resident tigers, and worried for the lack of genetic diversity within their park. That is because the Kaziranga National Park is more concerned with conserving wild tigers than private zoos are.
As striking as white and golden tigers are, novelty wears off, and dealers have had to seek other novelties to draw the crowds. White fur alone is so last-century; now you can get white tigers with pale or white stripes. Tigers which inherit two copies of recessive mutations for both white coat and wideband are solid white (so-called "snow white"), and are flogged to private zoos in an effort to revive the fading novelty of the white tiger.
The golden tiger has a recessive mutation in a different gene. The mutation is known as "Wideband", referring to its effects on a wide part of the hair shaft.
In 2014, a golden tigress was camera-trapped in the Kaziranga National Park, India. Rather than celebrating the presence of a golden tiger, the staff at the Kaziranga National Park saw it as evidence of inbreeding in their resident tigers, and worried for the lack of genetic diversity within their park. That is because the Kaziranga National Park is more concerned with conserving wild tigers than private zoos are.
As striking as white and golden tigers are, novelty wears off, and dealers have had to seek other novelties to draw the crowds. White fur alone is so last-century; now you can get white tigers with pale or white stripes. Tigers which inherit two copies of recessive mutations for both white coat and wideband are solid white (so-called "snow white"), and are flogged to private zoos in an effort to revive the fading novelty of the white tiger.
3. Ligers and tigons
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| Image source |
Apparently wild-type tigers aren't impressive enough (despite being the biggest wild cats in the world), so some bright spark decided to cross male lions with female tigers and see what happens. The cross resulted in a twelve-foot long monstrosity that looks like a lioness with a few faint markings here and there. It was named a "liger" in 1937 (corny designer breed names are nothing new).
These massive brutes are excellent examples for learning about imprinted genes and sexual conflict. A lioness may mate with different males, and rear the cubs together, so that cubs with different fathers are competing with each other for resources. Male lions therefore carry genes that are "imprinted" with special epigenetic labels that make their cubs larger.
Lionesses, on the other hand, want all their offspring to survive. They therefore imprint genes with epigenetic labels that make the offspring smaller. When the dad's imprinted genes and the mum's imprinted genes come together to make a cub, they cancel each other out.
In contrast to lionesses, a tigress only rears cubs from one father at a time. Tiger cubs from different fathers aren't in direct competition during rearing. Male tigers don't need to imprint their genes with enlarging labels. Tigresses don't need to produce their own imprinted genes to silence male imprinted genes. There is no conflict between the sexes in terms of cub size.
So when you cross a male lion with a female tiger, his imprinted genes go unchecked. The result is a cat that is larger than either of its parents.
Conversely, crossing a lioness with a male tiger produces a "tigon", which is no bigger than either parent.
These massive brutes are excellent examples for learning about imprinted genes and sexual conflict. A lioness may mate with different males, and rear the cubs together, so that cubs with different fathers are competing with each other for resources. Male lions therefore carry genes that are "imprinted" with special epigenetic labels that make their cubs larger.
Lionesses, on the other hand, want all their offspring to survive. They therefore imprint genes with epigenetic labels that make the offspring smaller. When the dad's imprinted genes and the mum's imprinted genes come together to make a cub, they cancel each other out.
In contrast to lionesses, a tigress only rears cubs from one father at a time. Tiger cubs from different fathers aren't in direct competition during rearing. Male tigers don't need to imprint their genes with enlarging labels. Tigresses don't need to produce their own imprinted genes to silence male imprinted genes. There is no conflict between the sexes in terms of cub size.
So when you cross a male lion with a female tiger, his imprinted genes go unchecked. The result is a cat that is larger than either of its parents.
Conversely, crossing a lioness with a male tiger produces a "tigon", which is no bigger than either parent.
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| Dad says "Grow big". Mum says "Stay small". Just be yourself, little cub. |
What's the point?
Aren't real tigers enough? Are people that bored of the real world that dealers have to create fake animals to impress them? This is why we shouldn't have nice things.
It is also why farming animals, or keeping them as pets, does not conserve them. When we take animals into captivity for amusement or food production, we change them. We create tangerine tornado leopard geckos or cinnamon pearl cockatiels - fine pets, but not fit for release into the wild. Natural selection favours individuals that are the best at surviving and reproducing. Artificial selection favours pretty, docile, easily-managed individuals.
If you want to help conserve tigers, you can visit and support a real zoo; you can donate to charities that are acting to conserve tigers or their habitat; you can support sustainable and ethical organisations by buying ethically-produced, sustainable food and clothing. Avoid products that use palm oil (unsustainable palm oil plantations use land that Sumatran tigers should be inhabiting), and if you want to see tigers in the wild, do your research into what organisation you are giving your money to and make sure that money goes towards conservation.
Always remember that habitat loss is one of the greatest drivers of extinction; it is not just the species that need to be conserved. They need a home to live in.
And don't give roadside zoos or their owners the attention that they crave.
It is also why farming animals, or keeping them as pets, does not conserve them. When we take animals into captivity for amusement or food production, we change them. We create tangerine tornado leopard geckos or cinnamon pearl cockatiels - fine pets, but not fit for release into the wild. Natural selection favours individuals that are the best at surviving and reproducing. Artificial selection favours pretty, docile, easily-managed individuals.
If you want to help conserve tigers, you can visit and support a real zoo; you can donate to charities that are acting to conserve tigers or their habitat; you can support sustainable and ethical organisations by buying ethically-produced, sustainable food and clothing. Avoid products that use palm oil (unsustainable palm oil plantations use land that Sumatran tigers should be inhabiting), and if you want to see tigers in the wild, do your research into what organisation you are giving your money to and make sure that money goes towards conservation.
Always remember that habitat loss is one of the greatest drivers of extinction; it is not just the species that need to be conserved. They need a home to live in.
And don't give roadside zoos or their owners the attention that they crave.
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| A real Sumatran tiger. |
*I refuse to call them "Orange". They are not orange! Have you SEEN a real tiger?? They are magnificent! Their semi-tame, deranged, inbred private zoo derivates have got nothing on their wild counterparts. So I will call real tigers that live in the wild and in real zoos "wild-type", because they look like wild tigers, and because in genetics, "wild-type" is a description of a typical natural phenotype.
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