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5. The guppy (Poecilia reticulata) is a small tropical fish. They are predated upon by various larger fish species.The males (top in picture) have great variation in the number and colour of spots on their body, ranging from one small spot to several spots and a grey colour to a variety of bright colours (pigment polymorphism). Males with brighter colours have greater breeding success
John Endler observed wild guppy populations and conducted several investigations on guppy populations in rivers with high levels and low levels of predation.In one investigation, he moved grey coloured males from a stream with high rates of predation to a stream with less predation.