Replace the subject line and body with your first blog post and hit send! Include pictures, an mp3, or anything else you want to share. It's just that simple.
A few days back I read about two very interesting animals- the liger and the tiglon. In this VERITAS I will tell you about these animals and also about a very interesting fact of genetics that makes these animals so different from each other.
A liger is the offspring of a male lion and a female tiger. So it is a hybrid of a male lion and a female tiger. They are much larger than both lions and tigers. Ligers are the largest cats in the world! It takes the best characteristics from both parents. It is very sociable like lions and like tigers, it loves swimming. Of course, lions and tigers would never mate in the wild. So a liger are typically born of captive lions and tigers.
A Tiglon is the offspring of a male tiger and a female lion. It is much smaller than both the lion and the tiger.
Let’s compare the sizes of these animals: a lion is about 8 feet in length and weighs about 250 kg. A Tiger is about 10 feet in length and weighs about 300 kgs. A Liger is about 12 feet in length and can weight upto 500 kg. So a Liger is about twice the size of a Tiger or a Lion! A Tiglon is about half the size of a Tiger and weighs about 160 Kgs.
That brings us to the most interesting question: when both are offspring of a tiger and a lion then what causes Ligers to be huge and Tiglons to be so small in comparison? The answer is amazingly interesting and due to a very interesting generic phenomena called genomic imprinting.
We inherit two copies of every gene: one from our mother and the other from our father. Usually both genes are active. It is true that the characteristics produced by these genes may show a particular domination but that is because the effect of one gene overrides the effect of the other. Both genes are active. But in a very small number of genes, one copy is turned off depending on whether it came from the mother or the father. So the fact that the copy came from the mother or father is “imprinted” on these genes and that turns it off or on. So for most genes, there is no information regarding which parent it came from. But some genes behave differently depending on whether they came from the mother or father. These genes have their “source” imprinted on them and that makes them turn off or turn on. In the human genome there are about 23000 genes out of which only 80 are imprinted.
Now, lets look at how Lions live. They live in prides. There are several male and female lions in a pride. Now, each male lion wants his offspring to be the biggest and most powerful. Only then would his future survival in the pride or group be assured. So an imprinted gene from the male lion promotes growth- an extraordinary growth. But the lioness’ concern is different- she will give birth to several cubs at once and does not want any one of them to grow at the others’ expense. Also a larger cub would mean danger for her also. So there is an imprinted gene from the lioness that curbs too much growth. When a lion and lioness mate and produce an offspring, the growth enhancing gene of the male lion is countered by the growth diminishing gene from the lioness to produce “normal” sized cubs.
Lets now look at how Tigers live. They are solitary creatures. Since they do not live in prides so male tigers do not have the “super-growth” imprinted gene. There is no question of competition within the group. And since male tigers do not have the “super-growth” imprinted gene so the tigress does not need the growth diminishing imprinted gene.
When a male lion mates with a tigress, he gives the “super-growth” imprinted gene. But the tigress has nothing to counter it. So we get a liger- a huge creature that the tigress finds it difficult to deliver naturally. Frequently a c-section is required to deliver this giant which becomes much bigger than a lion or a tiger.
When a male tiger mates with a female lion, he does not have a “super-growth” gene but the lioness has a growth diminishing gene which diminishes the growth of the offspring unchecked producing the much smaller tiglon.
When I first read the reason, I was delighted and amazed at the same time. It was 2 AM in the morning and I could not control my excitement at such an interesting fact! Knowledge is a great source of joy. In fact, the greatest source of joy!
Curioser and Curioser,
Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;