Melanin, including both eu‐ and pheomelanin forms, is the most common pigment type in animals and plays numerous adaptive roles. However, the effect of diet on melanin pigmentation is not well reviewed or synthesized. Understanding how diet influences melanin may lead to valuable insights such as explaining intraspecific variation or explaining when melanin‐based traits are plastic or condition dependent versus when they are prioritized or canalized. In order to assess the state of the literature and the current understanding of the effects of diet on melanin pigmentation we conducted a systematic literature search. We use the search results to highlight common patterns across animals. In particular we focus on three questions: Which dietary components can influence melanin? Which aspects of melanin‐based traits are influenced by diet? What factors can mediate the influence of diet on melanin? The effect of diet on melanin is complex and multifaceted. Diet itself can vary in a number of ways including diet quantity, protein content, fatty acid content and amount of metals and other micronutrients. We discuss the mechanisms by which these components influence melanin pigmentation. Diet can influence the size, darkness and colour of melanin‐based traits. Often, diet influences one of these aspects but not another, which may reflect the processes of melanin synthesis and distribution. Factors that mediate whether melanin pigmentation responds to dietary variation include the type of trait, life stage, sex and environmental stress. Methodology (e.g. degree of manipulation relative to natural conditions) can also influence results. These nuances should be considered when developing hypotheses about the effects of diet on melanin pigmentation. We conclude with important areas for future research, including the proximate mechanisms connecting diet and melanin, how diet affects internal melanin, how diet mediates costs of melanin pigmentation and how diet affects the evolution of melanin‐based traits. Overall, diet has important and complex effects on melanin and likely plays an important role in the ecology and evolution of melanin pigmentation. Read the free Plain Language Summary for this article on the Journal blog.

The sphinx moth genus Hyles comprises 29 described species inhabiting all continents except Antarctica. The genus diverged relatively recently (40–25 MYA), arising in the Americas and rapidly establishing a cosmopolitan distribution. The whitelined sphinx moth, Hyles lineata, represents the oldest extant lineage of this group and is one of the most widespread and abundant sphinx moths in North America. Hyles lineata exhibits the large body size and adept flight control characteristic of the sphinx moth family (Sphingidae), but it is unique in displaying extreme larval color variation and broad host plant use. These traits, in combination with its broad distribution and high relative abundance within its range, have made H. lineata a model organism for studying phenotypic plasticity, plant–herbivore interactions, physiological ecology, and flight control. Despite being one of the most well-studied sphinx moths, little data exist on genetic variation or regulation of gene expression. Here, we report a high-quality genome showing high contiguity (N50 of 14.2 Mb) and completeness (98.2% of Lepidoptera BUSCO genes), an important first characterization to facilitate such studies. We also annotate the core melanin synthesis pathway genes and confirm that they have high sequence conservation with other moths and are most similar to those of another, well-characterized sphinx moth, the tobacco hornworm (Manduca sexta).

When caring for their young, parents must compensate for threats to offspring survival in a manner that maximizes their lifetime reproductive success. In birds, parents respond to offspring threats by altering reproductive strategies throughout the breeding attempt. Because altered reproductive strategies are costly, when threats to offspring are limited, parents should exhibit a limited response. However, it is unclear if response to offspring threat is the result of an integrated set of correlated changes throughout the breeding attempt or if responses are a flexible set of dissociable changes that are stage‐specific. We test these hypotheses in a system where house wrens (Troglodytes aedon) compete for nesting cavities with Carolina chickadees (Poecile carolinensis) by usurping and destroying their nests during the early stage of the breeding attempt (the egg stage). Due to the specificity of the house wren threat, we can test whether parental responses to an offspring threat show flexibility and stage specificity or if parental strategies are an integrated and persistent response. We monitored nests in a natural population to compare life history traits of chickadees nesting in boxes that were in the presence of house wrens to chickadees nesting in boxes that did not overlap with house wrens. Carolina chickadees that nested near house wrens laid significantly smaller clutch sizes (early change in reproductive strategy) but did not alter nestling provisioning or nestling stage length (late change in reproductive strategy), suggesting that chickadees respond in a flexible and stage‐specific manner to the threat of house wrens. By responding only when a threat is highest, parents minimize the cost of antithreat responses. Our study suggests that parents can respond in subtle and nuanced ways to offspring threats in the environment and specifically alter reproductive behaviors at the appropriate stage.