Explaining color pattern diversity through the dynamic analysis of display

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Humans have been fascinated by the diversity of color for centuries, and the field of color science spans across art, philosophy, psychology and biology. Different people and societies have different color experiences, and even the same person perceives color differently depending on the background. Our ability to perceive this variation is thanks to a sophisticated color perception system, especially relative to other mammals. Other animals, such as birds, have even more complex color perception, and are among some of the most brilliantly colored animals on the planet. What are the underlying causes of this diversity? How does an animal’s surroundings, such whether it lives in forests or out in the open shape the evolution and perception of colors? One reason for our lack of understanding may be that color signals are frequently presented to observers, such as rivals, mates or predators, using movements of various body parts. Recent developments in high-speed video technology and computer programing now make it possible to accurately describe these movements. This project will therefore study the association between animal displays, habitat, and color by comparing closely related species. The over-arching goal of this work is to understand the diversity of color in nature, and ultimately, the diversity of how color is perceived.While long recognized that display movements are integral component of animal signals, it is only in the past few years that technology (e.g. high speed video cameras, essential because many species can perceive movements much more finely than humans) and analytical techniques (e.g. deep learning methods to trace trajectories of movements) have become sufficiently advanced that they can be used to study displays in a comparative context, thereby linking them to differences in color and ecology across species. The goal of this project is to quantify display behavior, environmental and ecological features, social context, color, and color patterns across the Old World leaf warblers (genus Phylloscopus), chosen because previous work has shown qualitative associations between light environment, color, and displays in the group. Closely related, sympatric, species will be compared across a gradient of habitat types to ask how plumage color (quantified through spectrophotometry) and threat display (quantified by playback experiments and high-speed video) are associated with habitat, including background color and granularity, and prevailing light environments. New methods of analysis derived from comparisons of morphological shape will be used to place display movements on continuous scales, thereby enabling them to be ranked across species. The essential concept is that displays vary with environment, and thereby influence the evolution of both color and color patterns beyond those predicted from static analyses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.