Genetics, development and evolution of adaptive pigmentation in vertebrates

Abstract

The study of pigmentation has played an important role in the intersection of evolution, genetics, and developmental biology. Pigmentation's utility as a visible phenotypic marker has resulted in over 100 years of intense study of coat color mutations in laboratory mice, thereby creating an impressive list of candidate genes and an understanding of the developmental mechanisms responsible for the phenotypic effects. Variation in color and pigment patterning has also served as the focus of many classic studies of naturally occurring phenotypic variation in a wide variety of vertebrates, providing some of the most compelling cases for parallel and convergent evolution. Thus, the pigmentation model system holds much promise for understanding the nature of adaptation by linking genetic changes to variation in fitness-related traits. Here, I first discuss the historical role of pigmentation in genetics, development and evolutionary biology. I then discuss recent empirically based studies in vertebrates, which rely on these historical foundations to make connections between genotype and phenotype for ecologically important pigmentation traits. These studies provide insight into the evolutionary process by uncovering the genetic basis of adaptive traits and addressing such longstanding questions in evolutionary biology as (1) are adaptive changes predominantly caused by mutations in regulatory regions or coding regions? (2) is adaptation driven by the fixation of dominant mutations? and (3) to what extent are parallel phenotypic changes caused by similar genetic changes? It is clear that coloration has much to teach us about the molecular basis of organismal diversity, adaptation and the evolutionary process.

Melanin-based skin spots reflect stress responsiveness in salmonid fish

“…Melanin-based colouration is also involved in ornamentation, camouflage and protection against physical damage, infectious agents, UV-light, and toxicants (Cesarini 1996;Majerus 1998;Mackintosh 2001;Roulin 2004a;Hoekstra 2006). The proximate and ultimate causes for the association between eumelanin-based ornamentation and other fitness-related traits such as immunocompetence remains debated (see e.g.…”

Born blonde: a recessive loss‐of‐function mutation in the melanocortin 1 receptor is associated with cream coat coloration inAntarctic fur seals

“…2011). Genetic variation at the MC1R has also been associated with melanic coat color variation in natural populations of around 20 species belonging to three mammalian orders, five avian orders, and lizards (Hoekstra 2006). However, the vast majority of wild species have not yet been studied (although see Theron et al.…”

Development and evolution of insect pigmentation: Genetic mechanisms and the potential consequences of pleiotropy

“…Unlike vertebrates, who use specialized cell types and cell migration to create body pigment patterns (reviewed in [9]), insects typically synthesize body color pigments and/or pigment precursors in their epidermal cells. In some cases, pigments are found within modified epidermal cells (e.g.…”