Panthera leo (Lion) and Panthera tigris (Tiger) are two large feline animals that are strikingly similar. The genus Panthera is comprised of the Lion, Tiger, Panther, and Leopard, all of which are in the "cat" family: Felidae. Generally, one assumes that the great tigers and mighty lions of this world are to be of separate morphological species do to simple physical attributes and phenotypical characteristics. However, this can prove to be a difficult matter to decipher and several reasons can be brought up as to why the two should simply be subspecies of one species.
First, let us discuss the rare occurrences, turned social fads, ligers. Tiglons (as they may also be called, depending on the mother) are a hybrid class of species between a Tiger and Lion. A Lion (male) and tigress (female) will produce a Liger while a lioness (female) and a tiger (male) will produce a tiglon. These rare hybrids are usually the result of human assistance and encouraged interbreeding. Nonetheless, these hybrids have demonstrated the ability for the two species to interbreed.
The definition of a "species" is traditionally a group of animals that can breed together to produce offspring. As one can see, this is quite evident within tigers and lions. However, recent changes to the meaning of "species" has taken to exclude the rise of hybrids. Many consider, now, that the offspring must be fertile. For the longest time it was thought that ligers and tigons were infertile and incapable of any reproduction. Even though that may be the majority case, in 1943 a 15-year-old female tigon bred with a lion to produce a female offspring. The little girl was raised until adulthood, despite health complications at birth.
Though it might seem impossible to now group the two big-cats separately, a striking blow has been delivered to the "one species" argument. Both offspring must indeed be fertile. While females tigons and ligers have been noted to rarely reproduce, the male hybrids are sterile. Such a complication means no chance for ever interbreeding, unless consistent tests prove otherwise. The assertion that a liger or tiglon male can never be fertile might be jumping the gun a little bit too early. After all, with studies done in the 19th century that asserted "no possible fertile offspring of Panthera tigris and Panthera leo was possible", maybe the hybrid males have a chance at fertilization.
- Life In the Fast Lane, Lion plus Tiger equals Liger