Ligers are just the tip of the iceberg when it comes to hybrids. While many hybrids exist in captivity, many (many) more are just now being recognized in the wild. Many times, we see hybrids in nature, but are unaware of the significance because we don’t know what to look for. Here are just a handful of other hybrids that exist in the world.
Top 10 Hybrids
Humans have hybridized with a number of non-human species throughout our history. Most humans on the planet carry approximately 1-4% Neanderthal DNA. Some carry Denisovan DNA.
Read more: http://humanorigins.si.edu/evidence/genetics/ancient-dna-and-neanderthals/interbreeding
A wholphin not exactly a whale dolphin cross. Strictly speaking it is the hybrid offspring of two different "dolphin-type" species. Kekaimalu is a "wholphin" hybrid that was born at the Hawaii Sea Life Park. Her parents were a false killer whale (a type of dolphin), and an Atlantic bottlenose dolphin. Kekaimalu has the black markings and size of a false killer whale and the otherwise grey skin of a dolphin. Don't let this lead you to the assumption that this type of hybridizing only happens in captivity. In 2017, off the coast of Kuai, a wild "wholphin" was photographed. This time it was the product of a romantic union between a melon-headed whale and a rough-toothed dolphin. These two examples are just the tip of the iceberg when it comes to Cetacean hybridization. Bottlenose dolphins have been known to interbreed with spinner dolphins, spotted dolphins, Risso's dolphins, and pretty much any other dolphin they can get their fins on. Narwals and beluga whales have been said to interbreed. Some even say that blue whales, fin whales and humpback whales hybridize. More research definitely needs to be done in this area.
Read more: https://www.livescience.com/63228-hybrid-dolphin-kauai.html
#3 Red Wolf
The red wolf is a critically endangered wolf species native to the southeastern United States. Only an estimated 20 red wolves still live in the wild, and only in a small region of North Carolina. Another 200 or so exist in captive breeding programs. The U.S. Fish and Wildlife Service, along with other organizations, have spent decades and many millions of dollars to protect and even reintroduce this unique canine back into its native range. Recent genetic evidence shows that the red wolf is most likely a grey wolf/coyote hybrid. Because U.S. legislation does not specifically protect hybrids, this species may lose its governmental protection and the project may lose funding. Scientists argue that the red wolf is important because it represents genetic diversity that exists nowhere else. Whether or not this species survives remains to be seen.
Read more: https://www.newscientist.com/article/2099192-red-wolf-may-lose-endangered-status-because-its-just-a-hybrid/
The "Blynx" is a naturally existing North American felid hybrid that occurs typically along the central and eastern border between the U.S. and Canada.
Read more: http://www.naturealmanac.com/archive/cougar/blynx.html
#5 Grolars and Pizzlies
Polar bear and grizzly (brown) bear hybridization seems to be happening more frequently. It has been suggested that this is the result of sea ice loss that is forcing polar bears to shift their range further south and to overlap the territory of the grizzly bear to a greater degree. While this may indeed be the case today, polar and grizzly bears have been hybridizing for thousands of years. The pinnacle of hybridization activity between the two species seems to have occurred during the last ice age, when polar bears had the largest range.
Read more: http://www.macroevolution.net/polar-bear-brown-bear-hybrids.html
#6 Darwin's Finches
Fourteen species of Darwin's finches occur on the Galápagos islands, having diversified from a common ancestor over the last 1–2 million years. Analyses of finch genomes show they have been exchanging genes by hybridizing throughout most of their history.
Read more: https://www.princeton.edu/news/2017/11/27/study-darwins-finches-reveals-new-species-can-develop-little-two-generations
#7 Blacktip Shark Hybrid
In 2012, scientists identified the first-ever hybrid shark off the coast of Australia, a discovery that suggests some shark species may respond to changing ocean conditions by interbreeding with one another. A team of 10 Australian researchers identified multiple generations of sharks that arose from mating between the common blacktip shark (Carcharhinus limbatus) and the Australian blacktip (Carcharhinus tilstoni), which is smaller and lives in warmer waters than its global counterpart. "To find a wild hybrid animal is unusual," the scientists wrote in the journal Conservation Genetics. "To find 57 hybrids along 2,000 km [1,240 miles] of coastline is unprecedented."
Read more: https://www.washingtonpost.com/national/health-science/first-ever-hybrid-shark-discovered-off-australia/2012/01/03/gIQAPy00YP_story.html?utm_term=.df1cd7fbf5c2
#8 Hybrid Sea Turtle
A hybrid green sea turtle/loggerhead turtle was discovered in 2016 off Florida's Space Coast. This is not the first hybrid sea turtle found. In 2008 a similar hybrid was found in North Carolina. Also, inter-species mating between loggerhead sea turtles and hawksbill and green sea turtles have been observed in the wild.
Read more: http://news.brevardtimes.com/2016/02/rare-hybrid-sea-turtle-discovered-in-florida.html
#9 Hybrid Sunfish
There are 11 species of sunfish, many of which readily hybridized. Fish hatcheries have started utilizing the phenomenon to stock ponds and lakes, as the hybrid offspring tends to be larger than parent species. Many other types of fish are known to hybridize, including: catfish, pike, trout, white bass, butterflyfish, clownfish, eels, seahorses, sharks, and many others.
Read more: https://fisheries.tamu.edu/pond-management/species/hybrid-sunfish/
#10 Copperhead/Cottonmouth Hybrid
Admittedly, for many people, this is the stuff of nightmares; two venomous snakes mating to produce a clutch of venomous hybrid babies. A National Geographic article documents this occurring in the wild.
Read more: https://news.nationalgeographic.com/2016/09/venomous-vipers-locked-in-mating-duel-different-species-combat/