Colour polymorphism associated with a gene duplication in male wood tiger moths

Brien, Melanie N.; Orteu, Anna; Yen, Eugenie C; Galarza, Juan A.; Kirvesoja, Jimi; Pakkanen, Hannu; Wakamatsu, Kazumasa; Mappes, Johanna

doi:10.1101/2022.04.29.490025

Cited by 8 publications

(9 citation statements)

References 93 publications

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“…Male hindwings across the species distribution range can have a red, yellow or white background with black patterning that covers variable proportions (ca 20-70%) of the wing. White and yellow colourations are partly produced by pheomelanin, whereas black is a dopamine-derived eumelanin (Brien et al 2022). Previous research has scored melanisation (the amount of eumelanin) of the hindwings as “plus” (with stripes, high melanin) or “minus” (without stripes, low melanin) (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Diet influences resource allocation in chemical defence but not melanin synthesis in an aposematic moth

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Rojas

Burdfield‐Steel

et al. 2023

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1. Aposematic organisms exhibit warning signals (primary defences) coupled with secondary defences, and competing for the same resources may lead to trade-offs in resource allocation. For animals that synthesise their chemical compounds de novo, resources, particularly proteins, can be expected to influence the investment in chemical defences and nitrogen-based warning colours such as melanin. 2. We manipulated protein availability in the larval diet of the wood tiger moth, Arctia plantaginis, to test how early life resource availability influences relevant life history traits, pigment production, and chemical defences. According to the resource allocation hypothesis, we expected individuals with less melanin (i.e., larger warning signals) to have more resources to allocate to chemical defences. 3. Then, we tested the efficacy of chemical defences of moths raised on diets with different protein content by presenting oat baits soaked with moth defensive fluids to wild-caught avian predators and observed their responses. 4. Early-resource environment affected chemical defences and developmental time of male moths but did not affect melanin expression in the wings. The amount of melanin in the wings, however, correlated with chemical defences: irrespective of the diet they were raised on, more-melanised individuals (i.e., smaller warning signal) produced more deterrent defensive fluids. Thus, the negative correlation between primary and secondary defences arises from more melanised individuals having better chemical defences, and not from resource allocation. 5. We conclude that the resources available in early life have an important role in the efficacy of chemical defences, but melanin-based warning colours are less sensitive to the variability of resources than other fitness-related traits.

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Section: Methodsmentioning

confidence: 99%

Diet influences resource allocation in chemical defence but not melanin synthesis in an aposematic moth

Ottocento

Rojas

Burdfield‐Steel

et al. 2023

Preprint

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“…The male coloration in the wood tiger moth is likely regulated by a yellow ‐family gene (Brien et al., 2022 ), which is conserved across insects (Ferguson et al., 2011 ) and has well‐known functions in the melanin production pathway (Wittkopp et al., 2002 ). Yellow genes have also been shown to have pleiotropic effects on life‐history and behavioral traits (Bastock, 1956 ; Massey et al., 2019 ; Connahs et al., 2021 ).…”

Section: Discussionmentioning

confidence: 99%

“…The wood tiger moth ( Arctia plantaginis ) represents a compelling study species to investigate how different selective pressures can act on a single color locus and maintain within‐population trait variation. In this system, male hindwing coloration is determined by a simple genetic basis (Suomalainen 1938 ; Nokelainen et al., 2022b ; Brien et al., 2022 ): a one locus‐two allele polymorphism (dominant W allele and recessive y allele), which translates into white (genotype: WW, Wy) and yellow (genotype: yy) males. Because this is an aposematic moth species, the color trait is not only used for intraspecific communication (i.e., sexual selection) but also to advertise their unpalatability to predators (i.e., interspecific communication).…”

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Heterozygote advantage and pleiotropy contribute to intraspecific color trait variability

et al. 2022

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The persistence of intrapopulation phenotypic variation typically requires some form of balancing selection because drift and directional selection eventually erode genetic variation. Heterozygote advantage remains a classic explanation for the maintenance of genetic variation in the face of selection. However, examples of heterozygote advantage, other than those associated with disease resistance, are rather uncommon. Across most of its distribution, males of the aposematic moth Arctia plantaginis have two hindwing phenotypes determined by a heritable one locus‐two allele polymorphism (genotypes: WW/Wy = white morph, yy = yellow morph). Using genotyped moths, we show that the presence of one or two copies of the yellow allele affects several life‐history traits. Reproductive output of both males and females and female mating success are negatively affected by two copies of the yellow allele. Females carrying one yellow allele (i.e., Wy) have higher fertility, hatching success, and offspring survival than either homozygote, thus leading to strong heterozygote advantage. Our results indicate strong female contribution especially at the postcopulatory stage in maintaining the color polymorphism. The interplay between heterozygote advantage, yellow allele pleiotropic effect, and morph‐specific predation pressure may exert balancing selection on the color locus, suggesting that color polymorphism may be maintained through complex interactions between natural and sexual selection.

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“…Each pooled sample, 4 for H. misippus and 3 for H. bolina, was sequenced to 20M reads. RNA was extracted using a modified Trizol protocol using the same protocol as in (Brien et al 2022).…”

Section: Methodsmentioning

confidence: 99%

“…reads. RNA was extracted using a modified Trizol protocol using the same protocol as in (Brien et al 2022).…”

Section: Rna-seq Sample Preparationmentioning

confidence: 99%

TheHypolimnas misippusgenome supports a common origin of the W chromosome in Lepidoptera

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McCarthy

Hornett

et al. 2023

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Moths and butterflies (Lepidoptera) have a heterogametic sex chromosome system with females carrying ZW chromosomes and males ZZ. The lack of W chromosomes in early diverging lepidopteran lineages has led to the suggestion of an ancestral Z0 system in this clade and a B chromosome origin of the W. This contrasts with the canonical model of W chromosome evolution in which the W would have originated from the same homologous autosomal pair as the Z chromosome. Despite the distinct models proposed, the rapid evolution of the W chromosome has hindered the elucidation of its origin. Here, we present high-quality, chromosome-level genome assemblies of two Hypolimnas species (Hypolimnas bolina and Hypolimnas misippus) and use the H. misippus assembly to explore the evolution of W chromosomes in butterflies and moths. We show that in H. misippus the W chromosome has higher similarity to the Z chromosome than any other chromosome, which could suggest a possible origin from the same homologous autosome pair as the Z chromosome. However, using genome assemblies of closely related species (ditrysian lineages) containing assembled W chromosomes, we present contrasting evidence suggesting that the W chromosome might have evolved from a B chromosome instead. Crucially, by using a synteny analysis to infer homology, we show that W chromosomes are likely to share a common evolutionary origin in Lepidoptera. This study highlights the difficulty of studying the evolution of W chromosomes and contributes to better understanding its evolutionary origins.

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Colour polymorphism associated with a gene duplication in male wood tiger moths

Cited by 8 publications

References 93 publications

Diet influences resource allocation in chemical defence but not melanin synthesis in an aposematic moth

Diet influences resource allocation in chemical defence but not melanin synthesis in an aposematic moth

Heterozygote advantage and pleiotropy contribute to intraspecific color trait variability

TheHypolimnas misippusgenome supports a common origin of the W chromosome in Lepidoptera

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