Snakes have evolved extraordinary diversity in coloration, which is strongly linked to fitness and represents a major axis of phenotypic diversity in snakes. In this chapter, we discuss the integrative biology of snake coloration and identify future research targets in the field. First, we explore the ways that researchers define and quantify snake coloration, characterize interspecific diversity, and delimit intraspecific diversity (including ontogenetic color shifts, sexual dichromatism, geographic color variation, and color polymorphism). Second, we synthesize what is known about the mechanisms of the production of coloration in snakes, from identifying the sources of color (pigments or structural color) and color texture (matte and iridescence) to classifying the cells and tissues involved in color and color pattern and describing the quantitative and transmission genetics of snake coloration. Third, we discuss historical and contemporary approaches to studying the functional biology of snake coloration. We achieve this by considering snakes as both signalers and receivers of color information and discussing tradeoffs across the multiple functions of snake coloration, such as thermoregulation and predator defense. Fourth, we examine evidence for the drivers of color evolution by considering the role of neutral and selective forces that impact snake coloration, identifying the ecological agents of selection, and discussing potential evolutionary constraints on coloration in snakes. Finally, we explore macroevolutionary patterns of snake coloration, including phylogenetic tests of color variation, directionality of transitions and rates of change, and ecological correlates of coloration in snakes. Ultimately, future research that unites these conceptual approaches and data across disciplines will be crucial for understanding the factors that structure color variation across the snake tree of life.
