Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

11-19-2021

Graduate Advisor

Dr. Aimee S Dunlap

Committee

Dr. Zuleyma Tang-Martinez

Dr. Robert J. Marquis

Dr. Nathan Muchhala

Dr. R. Fredrik Inglis

Dr. Nathan Morehouse

Abstract

Animals interact with their environment and acquire information from it. Information can be processed by their sensory systems and influence behavior, often mediated through mechanisms of decision-making and learning. Animal pollinators acquire information from flowers and use this information to make decisions about the flowers they visit. My research aimed to understand the role of color vision in a tropical pollinator, the orchid bee Euglossa dilemma. Chapter 1 is a review exploring pollination through the lens of prepared learning. Prepared learning proposes that animals learn some associations better than others due to an evolved match with the environment. I offer a brief history of the concept, build a conceptual framework, explore examples of prepared learning in pollination, and suggest future directions for the field. Chapter 2 characterizes color vision in the orchid bee Euglossa dilemma. I compare E. dilemma's color vision to other related bees by comparing their spectral sensitivity curves and opsin protein amino acid sequences. My results show that E. dilemma is a trichromat, with peaks of Green, Blue, and Ultraviolet in similar regions to other bees. Ultraviolet photoreceptors are the most conserved among the compared bees, while blue photoreceptors and opsin proteins are the least conserved. Chapters 3 explores orchid bee color vision use, focusing on color choice and preference. Color choice was affected by time of day and humidity, and individual orchid bees show variability in their color preferences. Color preference was not affected by the abiotic or biotic factors measured nor predicted by a bee's first choice. Chapter 4 tests whether the presence of scent affects the bees’ choices in color preference trials. Scent affected motivation to engage, but not participation or color preference. I also tested for the ability to condition a sugar reward to a scent cue but did not detect scent learning. My results show that male orchid bees attend to scent cues, delaying their choices about color cues when scent is present. The results from this dissertation add to our knowledge of bee decision-making, and the methodologies developed and implemented here can be used in other populations of wild bees.

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