The Guppy is an extremely common fish in the aquarium trade, and is not considered vulnerable in the wild (Fishbase.org). They originally come from South America and the Caribbean: Venezuela, Barbados, Trinidad, northern Brazil and the Guyanas (Fishbase.org), but the guppies seen in pet shops are captive bred. The vast majority of guppies seen in the trade are either fancy guppies that have been selectively bred for beauty, or feeder guppies, which are not bred for beauty and are sometimes used as food for predatory fishes. Guppies breed very readily in captivity. They can interbreed with the Endler’s Livebearer, Poecilia wingei (Poeser et al.), and the two species should therefore be kept in separate tanks.
Unfortunately, guppies have become an invasive species in Asia, Australasia-Pacific, Europe, North America, and South America. They were intentionally introduced to many of these areas in order to control mosquitoes, but some feral populations are probably descended from escaped pets (Global invasive species database).
Global invasive species database. Compiled by National Biological Information Infrastructure (NBII) and Invasive Species Specialist Group (ISSG)
Poeser, F., Kempkes, M., Isbrucker, I. 2005 Contributions to Zoology. Description of Poecilia (Acanthophacelus) wingei, n. sp. from the Paria Peninsula, Venezuela, including notes on AcanthophacelusEigenmann, 1907 and other subgenera of Poecilia Bloch and Schneider, 1801 (Teleosti, Cyprinodontiformes, Poeciliidae) http://dpc.uba.uva.nl/ctz/vol74/nr01/art07