Exploring Variation in Learning Ability in Pieris rapae, the Cabbage White Butterfly

Abstract

Learning abilities allow animals to modify their behaviors based on experience; such plasticity provides an adaptive mechanism for responding to environmental unpredictability. As with any heritable trait subject to natural selection, learning ability can vary both within and across insect species, suggesting costs to maintaining the ability to learn. In this thesis I explored two different aspects of variation in learning ability in the Cabbage White Butterfly, Pieris rapae. First, I evaluated whether P. rapae learn two different visual stimuli (color and shape) at the same rate and proficiency in a foraging context. While learning abilities of different stimuli within a given sensory modality have been studied in other insects, visual learning abilities aside from color in butterflies have received little attention. I found that while Pieris rapae is capable of learning shape in association with a food reward, color is a more salient cue in a foraging context. Second, I compared life history traits, foraging behavior, and learning abilities of a wild and a laboratory population of P. rapae to assess how differences in both genetic makeup and environment can alter phenotypes within a species. I found that the two populations differ in timing of development for several life stages, and that foraging behavior and learning abilities diverged based on population origin. The findings from these two studies provide new evidence for how variation in learning abilities depends on type of stimulus, and can also be affected by environmental pressures and genetic processes.