It's a struggle for existence because the animals have to do many things to survive
There are only feral populations in some parks/zoos. They are only truly wild in Pakistan/India
In the days when the Wild West was in existence, there were several different food sources. They included buffalo, squirrel, wild turkey, pheasant, sheep, cows, and fish. Plants that were indigenous to the area were also used.
Artificial Selection
There are over 25,000 species of honey bees which exist throughout the world. How many are in existence is hard to say as live in the wild and are not counted.
European bison were hunted to extinction in the wild in 1919. Since then it has been reintroduced from captive bread individuals held in various parts of the world. Adding up the heard statistics from the various reintroductions, there are probably around 5000 specimens in existence. Non of these can be classed as truly wild.
Chinchillas in the wild are rarely viewed because they are almost extinct so I dont believe
Mr. Toad's Wild Ride. It has been in existence since the opening in 1955. Not available at Disneyworld though. Ribbit, ribbet!
As far as the first horse breed still in existence its been discovered that the Caspian Horse (which is a very small and finely built pony in todays standards) was even older breed than the arabian, but that is yet to be proved. The Asiatic Wild Horse, is the only breed in existence older than the Caspian.
Existence is a noun.
She believes in the existence of God. The existence of gravity is a fact.
Both of the spellings you have given are the same.The correct spelling is existence. So both are correct."I believe in the existence of alien life".