Hybrids, or mutants, are offspring resulting from cross-breeding between two species. Different species have different number of chromosome, for example lion, tiger, human, horse, donkey.. all of which are different species with different sets of chromosome in their gene.
Interracial marriage is not considered interspecies, so it is inappropriate to crown someone whose parents aren't from the same lineage with the title "mutant" =P
Cross breeding between different species has created awesome(and horrible) creatures such as the liger, tigon, zorse, wholphin, grolar bear, and so on. These creatures, some of which are natural occurring (for example wholphin, grolar bear), are created by genetic scientists to fulfill the insatiable imagination of mankind.
One very interesting fact about hybridization is that when two species with very distinct sets of chromosome cross-breed, the resulting zygote will simply die off, or if succeeded to form, they would be born sterile, or deformed, unable to pass down their hybrid gene. Hence there is no extreme mutants in nature; for example man cross-breeding with horse to create centaurs; or rhino cross-breeding with horse to create unicorn, simply because the significant difference of the genes causes the zygote to perish within the womb.
Related species, however, could survive the zygote-forming ordeal. For example the grolar bear is the offspring of a grizzly bear and a polar bear. This is an naturally occurring phenomenon, as the grizzly's territory often overlap with that of the polar bear. There was a case where a grolar bear was shot, and genetic analysis found out that one of its parents was also a grolar bear, possibly a fission of grolar bear and polar bear OR grolar bear with grizzly bear.
So how to differentiate a natural occurring mutation and a man-made one? Simply by looking whether the resulting offspring is sterile: natural selection will try to maximize the longevity of a species. A hybrid born naturally will have the trait of both its parents, thus maximizing the success of the hybrid itself. Thus this successful gene should be passed down to the next generation. This process is a very slow one, which explains why evolution takes millions of years to
The successful hybrid will gain the upper hand in life, its parent-species slowly die off due to inability to compete, and this explains why we do not have Homo Erectus amongst us today. Genetic analysis shows that 99.84% of our gene is similar to that of Neanderthals, another extinct human sub-species originated from Europe and Asia. This shows that our ancestors cross-bred, produced homo sapiens, and they themselves slowly died off. What great sacrifice they've made.
Alright, done with the technical, now to the examples.
The liger is a hybrid cross between a male lion (Panthera leo) and a tigress (Panthera tigris), hence has parents with the same genus but of different species. A male liger has mane, like its father the male lion. Ligers are, however, born sterile-- which means there is no liger in the wild--nature would not permit it. Ligers are huge~ which is why I said hybridization creates awesome and horrible animals. Imagine a liger attacking you, a 400 kg supercat..
One more thing, ligers generally grow larger than both its parents put together. So they are the ultimate cat really.. Ligers enjoy swimming which is a characteristic of tigers and are very sociable like lions, but unlike tigons, ligers are more likely to live past birth. However ligers may inherit health issues or behavioural issues due to conflicting inherited traits, but this depends on the genetic traits of the parents.
Although the Asiatic lion lives in the Gir forest of India, its territory doesn't overlap with the tiger's, because the area is too dry to accommodate the tiger. The tiger needs water more than any other cats.
Zorse is a hybrid between zebra and horse. Awesome creature with horrible temper. Zebras are aggressive animals, and zorse gets the best out of that trait. It is also naturally sterile.
On May 15, 1985, trainers at Hawaii Sea Life Park were stunned when a 400-pound gray female bottlenose dolphin named Punahele gave birth to a dark-skinned calf that partly resembled the 2,000-pound male false killer whale with whom she shared a pool. The calf was a wholphin, a hybrid that was intermediate to its parents in some characteristics, like having 66 teeth compared with the bottlenose’s 88 and the 44 of the false killer whale, a much larger member of the dolphin family.
Wholphin is not sterile~ =) one very interesting question arises here: how do the animals know whether their offspring is heading towards evolutionary dead end? Because for the liger case, the animal is sterile, and coincidently the parents are not investing their time and energy to produce a sterile species, the same goes to the mule and zorse--which is why they are man-made. How would the animals know that their offspring is fertile, like the grolar bear and wholphin, which occur naturally? Ponder upon that please =P
In 2006, a hunter in the Canadian Arctic shot a bear that had white fur like a polar bear’s but had brown patches, long claws and a hump like a grizzly bear’s. DNA analysis confirmed the animal was a hybrid of the two species.
Hybridization is very common in the world of plants. I need not proceed further. Just look out your window and look at the hybrid plants in your garden, or go to your fridge and look at the hybrid tomatoes, the hybrid rice, etc. Hybridization brings out the best of each species and incorporates them into a single entity. It's very selfish of mankind to execute this species-exterminating process upon the defenceless plants.
Now that we have seen the power of genetic engineering, we should ponder upon the ethical questions instead.
Hybridization is a wonderful tool to enhance our lives; food of higher quality, tougher endurance, stronger immunization.
But by doing this we are accelerating what is meant to be natural by mother nature. A simple example, let's take the rice. Apart from humans, there are animals and insects feeding on rice as well. When we gather the rice, modify its gene via hybridization and indirectly exterminate the parents(some may argue that the parents are not exterminated, but in the case of African killer bee in America, the bee escaped from captivity and rooted itself in the local ecosystem, and is currently threatening the local bees. This is why I said "Indirectly exterminate"), we are actually terminating the food source of the animals and insects that are depending on it.
And what worst, we're doing it for the benefit of mankind only, regardless of any other species.
Apart from that, hybrid animals are born sterile, or deformed, and in the case of liger and zorse, with weaker immune system--which means an early death is inevitable. Even without death, suffering would be plentiful. Knowing that beforehand, and yet proceed on to cross-breed the two species, are we not selfish enough to sacrifice other species to satisfy our own curiosity?
Beyond hybridization, genetic engineering has been able to clone a certain species which deemed beneficial to us. The religious bunch call this "playing God", and we call this "unethical". Who knows, there could be some scientists who are secretly working on hybridization of human with chimps, and then clone the animals for circus. Or perhaps some of them possess evil agendas and clone several Saddam Hussein or Adolf Hitler =P
Genetic engineering no doubt has given us an advantage over other species. We are modifying our food to serve ourselves better. Even when diseases and plagues break out, our food will be able to withstand the infection with superior immunity. But it also has its down side. It is all down to perspective, and the level of education one has had. It just shows that humans are able to mimic what nature is capable of producing, albeit with less effective results.