I've been wanting to share this with you all for awhile.
You know how I'm interested in exotic animals, especially if they're cute and/or presented in a neat little list (cfr. my posts on the newly-discovered atelopus frog and on the axolotl and other bizarre sea creatures). Well, last month, my friend Josie sent me a link to a blog with a list of the Top 10 Hybrid Animals which also tickled my fancy.
An interspecific hybrid is created when a male and female from two closely-related species (usually from the same genus) mate and produce offspring. This offspring shares characteristics with both its parents. Normally hybrids are sterile: this prevents genetic characteristics from passing between the two gene pools and thus explains why they are two distinct species. This sterility is sometimes due to a difference in the number of chromosomes: for example, donkeys have 62 chromosomes, horses have 64, and mules have 63. Rarely, however, a fertile hybrid will appear: scientists have documented cases in which a female mule has produced a foal with a donkey or horse father, and the Top 10 post itself mentions female tigon/ligers successfully mating with male lions and tigers.
Many hybrids result from animal husbandry by humans, however interspecific mating is not unknown in the wild. For example, DNA tests have confirmed that a bear shot to death by a hunter in Canada's Northwest Territory was a grizzly/polar bear hybrid. This confirmed scientists' hypothesis that a hybrid zone where such births naturally occur might exist where the two species' habitats overlap.
Hybrid animals are often referred to by a portmanteau formed by combining the names of the two parent species: traditionally the father's species forms the first part of the name, hence:
male lion + female tiger -> liger
male tiger + female lion -> tigon
Among the hybrids which made the bloggers' Top 10 you can find ligers/tigons (which Napoleon Dynamite taught us are bred for their skill in magic) as well as camas (half camel, half llama), grolar/pizzly bears, iron age pigs (half pig, half wild boar), and zebroids (half zebra, half horse/donkey) such as the zony pictured above. Presumably the mule, which is probably the most common hybrid species, was too mundane to be included in the list; and the featured wolf dog (as the comments point out) is actually an intraspecific hybrid given that scientists today generally consider the domestic dog and the wolf to be subsets of the same species (canis lupus).
Wikipedia also contains information about some other hybrids such as the Dzo (half yak, half cow) and the beefalo (half bison, half cow).
It probably goes without saying, but you're not going to find any man-beast hybrids because our species' closest relatives (chimpanzees, gorillas, orangutans) are too disimilar from us for any sort of offspring to be created from interbreeding. The other members of our species' genus such as homo erectus and homo halibus are the ancestors of modern man and no longer walk the Earth.
Song I'm currently listening to (in honor of this post): Blair - Wolfboy
Book I'm currently finishing up: Ubik by Philip K. Dick