Complex sentence: The American alligator ("Alligator mississippiensis ", sometimes referred to colloquially as a gator) is a reptile native only to the Southeastern United States, and is one of the two living species of alligator, a genus within the family"Alligatoridae".
Split into simpler sentences: The American alligator ("Alligator mississippiensis "), sometimes referred to colloquially as a gator, is a reptile endemic only to the Southeastern United States. It is one of the two living species of alligator, in the genus"Alligator ", within the family"Alligatoridae".