Population differences in predator recognition and attack cone avoidance in the guppy Poecilia reticulata

The level of predatory threat encountered by fish may vary from population to population. In Trinidad, for example, guppies in the Lower Aripo River encounter a range of fish predators. Guppies from the Paria River, by contrast, encounter few fish predators but probably experience a high degree of predation from freshwater prawns, Macrobrachium spp. Predation risk from all types of aquatic predators is low for guppies from the Upper Aripo River. Inspection behaviour allows prey fish to recognize and assess potential predators. The risk associated with this behaviour can be minimized if the attack cone around the predator's jaws is avoided. This experiment investigated attack-cone avoidance behaviour during inspection of either a fish predator, Rivulus hartii or a macrobrachium, M. crenulatum, by wildcaught guppies. Inspecting Lower Aripo guppies kept a large distance between themselves and the rivulus. They also selectively avoided the dangerous mouth region. These Lower Aripo guppies did not, however, display attack-cone avoidance in the presence of the macrobrachium. Guppies from the Paria population were most wary when inspecting the macrobrachium. Upper Aripo guppies showed no attack-cone avoidance and displayed poor recognition of both predators. The results demonstrate that fish skilled at dealing with one type of predator gain no automatic advantage when faced with a novel predator. They also show that fish exposed to high levels of predation in the wild will not necessarily be more cautious in circumstances where the level of danger is unknown.