Colour biases in learned foraging preferences in Trinidadian guppies

Learning allows animals to adaptively adjust their behaviour in response to variable but predictable environments. Stable aspects of the environment may result in evolved or developmental biases in the systems impacting learning, allowing for improved learning performance according to local ecological conditions. Guppies (Poecilia reticulata), like many animals, show striking colour preferences in foraging and mating contexts and guppy artificial selection experiments have found that the form and progress of evolved responses to coloured stimuli differ depending on stimulus colour. Blue colouration is thought to typically be a relatively unimportant food cue in guppies. This raises the possibility that learned foraging associations with blue objects are formed less readily than with other colours. Here, guppies were rewarded for foraging at green or blue objects in two experiments. Guppies readily foraged from these objects, but learning performance differed with rewarded object colour. With equal amounts of training, the preference for green objects became stronger than the preference for blue objects. These differences in performance were not attributable to differences in initial preferences or to foraging more on one colour during training. These findings suggest that associative pairings within a single sensory modality that do not have a historic relevancy can be more difficult for animals to learn even when there is no clear initial bias present.