They’re known as the yellow-belied kingsnake or the prairie kingsnake, slithering from Nebraska to Virginia and Texas to Florida, and now researchers say they’re not one species but three.

Researchers at the American Museum of Natural History and City University of New York’s College of Staten Island said in an analysis published by Molecular Phylogentics and Evolution the snakes evolved into separate species because of the distinct ecosystems in which they live.

Two of the subspecies initially were classified as distinct species when they were first discovered but then demoted. The new analysis re-elevates them.

L.calligaster is found in the prairies west of the Mississippi River, L.rhombomaculata in the forests east of the Mississippi, and L.occipitolineata in the wet prairies of South Florida.

The researchers said the assumption the Mississippi River was responsible for creating the separate species by creating a barrier that prevented the snakes from breeding with their counterparts is wrong, saying the ecosystems themselves played a greater role.

“You go from the forest to the grasslands and ‘voila!’, you make a different species,” said Frank Burbrink, an associate curator in the museum’s Department of Herpetology, one of the study’s authors. He also has studied this effect on copperhead snakes.

Burbrink said this same mechanism likely also applies to other animals.

“All of the animals that have a range over these areas should probably be restudied,” Burbrink said.

“Even though the U.S. has been explored scientifically for more than 200 years, we still don’t fully know what’s in our backyard.”

The yellow-belied kingsnake lives in open and semi-open areas, including weedy fields, pastures, prairies, rocky hillsides, thickets, open woodland, barrier beaches, salt-grass savannas, marshy areas and residential areas. It spends much of its time underground or under surface cover.

The nonvenomous snakes are light brown or gray, with dark gray, dark brown or reddish-brown blotching. They can grow as long as 40 inches and often are confused with various kinds of rat snakes. They eat primarily rodents but also lizards, frogs and sometimes other snakes.