Sex Differences In 20-Hydroxyecdysone Hormone Levels Control Sexual Dimorphism InBicyclus anynanaButterfly Wing Patterns

In contrast to the important role of hormones in the development of sexual dimorphic traits in vertebrates [1], the differentiation of these traits in insects is attributed exclusively to variation in cell-autonomous mechanisms controlled by members of the sex determination pathway [2], such as doublesex (dsx). Although hormones can shape the development of sexual traits in insects, and interact with dsx to create dimorphisms, variation in hormone levels are not known to cause dimorphism in these traits [3]. Here we show that butterflies use sex-specific differences in 20-hydroxyecdysone (20E) hormone titers to create sexually dimorphic wing ornaments, without the local involvement of dsx. Females of the dry season (DS) form ofBicyclus anynanadisplay a larger sexual ornament on their wings than males, whereas in the wet season (WS) form both sexes have similarly sized ornaments [4]. High levels of circulating 20E during larval development in DS females and WS forms cause proliferation of the cells fated to give rise to this wing ornament, and results in sexual dimorphism in the DS forms. This study advances our understanding of how the environment regulates sex-specific patterns of plasticity of sexual ornaments and conclusively shows that sex-specific variation in hormone titers can play a role in the development of secondary sexual traits in insects, just like they do in vertebrates.

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Sex Differences in 20-Hydroxyecdysone Hormone Levels Control Sexual Dimorphism in Bicyclus anynana Wing Patterns

Molecular Biology and Evolution ◽

10.1093/molbev/msx301 ◽

2017 ◽

Vol 35 (2) ◽

pp. 465-472 ◽

Cited By ~ 14

Author(s):

Shivam Bhardwaj ◽

Kathleen L Prudic ◽

Ashley Bear ◽

Mainak Dasgupta ◽

Bethany R Wasik ◽

...

Keyword(s):

Sex Differences ◽

Sexual Dimorphism ◽

Bicyclus Anynana ◽

Hormone Levels ◽

Wing Patterns

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Relationships between male secondary sexual traits, physiological state and offspring viability in the three-spined stickleback

BMC Ecology and Evolution ◽

10.1186/s12862-021-01958-8 ◽

2022 ◽

Vol 22 (1) ◽

Author(s):

Violette Chiara ◽

Alberto Velando ◽

Sin-Yeon Kim

Keyword(s):

Oxidative Dna Damage ◽

Physiological State ◽

Courtship Behaviour ◽

Mtdna Copy Number ◽

Secondary Sexual Traits ◽

Sexual Ornaments ◽

Study Population ◽

Sexual Traits ◽

Secondary Sexual

Abstract Background Sexual signals produced by males play a central role in sexual selection, but the relationship between these traits and the quality of the bearer are often ambiguous. Secondary sexual traits may represent genetic quality of the bearer, resulting in positive relationships with physiological state, or may be costly to produce, showing trade-off with physiological state. A number of studies have explored the relationships between secondary sexual traits and other functional traits, but few have studied their fitness consequences. We studied the link between diverse physiological traits and both morphological and behavioural sexual traits and examined how their interplay influences offspring viability in the three-spined stickleback. Results Male sticklebacks showing nest building and courtship behaviour were smaller than those not investing in reproductive activities. There was no evidence that the expression of red nuptial colouration and the quality of courtship behaviour of males are positively related to their metabolic rates, swim ability, oxidative damage and mtDNA copy number. However, individuals showing larger red nuptial colour areas had higher levels of oxidative DNA damage in their sperm. Male courtship behaviour and aggressiveness, but not red colour area, were good predictors of offspring hatching and survival. Conclusions Our results suggest that, in our study population at the southern edge of the species’ distribution, sexual colouration of male sticklebacks was not a good indicator of their body state, but both courtship quality and aggressiveness during the courtship are reliable cues of their gamete quality, influencing the viability of their offspring. Thus, females that choose mates based on their courtship behaviour will have high fitness. In the study population, which represents a fast pace-of-life with high reproductive rate and short lifespan, sexual ornaments of males may not honestly signal their physiological and physical state because they invest at maximum in a single reproductive season despite high costs.

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Sexual dimorphism and condition dependence in the anal pad of the small Indian mongoose (Herpestes auropunctatus)

Canadian Journal of Zoology ◽

10.1139/cjz-2014-0288 ◽

2015 ◽

Vol 93 (5) ◽

pp. 397-402

Author(s):

M.A. Owen ◽

D.C. Lahti

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Indirect Evidence ◽

Condition Dependence ◽

Secondary Sexual Traits ◽

Herpestes Auropunctatus ◽

Sexual Traits ◽

Indian Mongoose ◽

Small Indian Mongoose ◽

Secondary Sexual

Secondary sexual traits tend to be sexually dimorphic, and theory predicts that such traits should also be condition-dependent in a sex-specific manner. We investigate these phenomena in a field study of the small Indian mongoose (Herpestes auropunctatus (Hodgson, 1836); formerly Herpestes javanicus (É. Geoffroy Saint-Hillaire, 1818)), in the first attempt at understanding secondary sexual traits and sexual selection in this species. Small Indian mongooses are solitary and nonterritorial, and they likely depend on chemical (scent) rather than visual or acoustic signals for communication. Additionally, they possess a fleshy projection around their anus, the anal pad, thought to aid in scent-marking. Our results revealed strong male-biased sexual dimorphism in mass, skull and body lengths, canine diameters, and anal pad area. After controlling for the influence of body length, males were 31% heavier and possessed anal pads that were 68% larger than females’. Additionally, anal pad size was positively related to body size in males but not in females and was condition-dependent in males but not in females. Taken together, our findings provide indirect evidence that the anal pad might have evolved, at least in part, via sexual selection.

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apterous A specifies dorsal wing patterns and sexual traits in butterflies

10.1101/131011 ◽

2017 ◽

Cited By ~ 2

Author(s):

Anupama Prakash ◽

Antónia Monteiro

Keyword(s):

Transcription Factor ◽

Regulatory Networks ◽

Sexually Dimorphic ◽

Color Patterns ◽

Bicyclus Anynana ◽

Sexual Ornaments ◽

Wing Patterns ◽

Specific Factors ◽

Different Color

AbstractButterflies have evolved different color patterns on their dorsal and ventral wing surfaces to serve different signaling functions, yet the developmental mechanisms controlling surface-specific patterning are still unknown. Here, we mutate both copies of the transcription factor apterous in Bicyclus anynana butterflies using CRISPR/Cas9 and show that apterous A functions both as a repressor and modifier of ventral wing color patterns, as well as a promoter of dorsal sexual ornaments in males. We propose that the surface-specific diversification of wing patterns in butterflies proceeded via the co-option of apterous A into various gene regulatory networks involved in the differentiation of discrete wing traits. Further, interactions between apterous and sex-specific factors such as doublesex may have contributed to the origin of sexually dimorphic surface-specific patterns. Finally, we discuss the evolution of eyespot pattern diversity in the family Nymphalidae within the context of developmental constraints due to apterous regulation.Significance statementButterflies have evolved different wing patterns on their dorsal and ventral wing surfaces that serve different signaling functions. We identify the transcription factor, apterous A, as a key regulator of this surface-specific differentiation in butterflies. We also show a role for apterous A in restricting the developmental origin of a novel trait, eyespots, to just the ventral wing surface. Dorsal-ventral differentiation of tissues is not just restricted to butterfly wings but occurs in many other organs and organisms from arthropods to humans. Thus, we believe that our work will be of interest to a diverse group of biologists and layman alike interested in the role of development in shaping biodiversity.

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apterous A specifies dorsal wing patterns and sexual traits in butterflies

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.2685 ◽

2018 ◽

Vol 285 (1873) ◽

pp. 20172685 ◽

Cited By ~ 16

Author(s):

Anupama Prakash ◽

Antónia Monteiro

Keyword(s):

Regulatory Networks ◽

Sexually Dimorphic ◽

Bicyclus Anynana ◽

Developmental Constraints ◽

Sexual Ornaments ◽

Downstream Effectors ◽

The Family ◽

Wing Patterns ◽

Specific Factors ◽

Colour Patterns

Butterflies have evolved different colour patterns on their dorsal and ventral wing surfaces to serve different signalling functions, yet the developmental mechanisms controlling surface-specific patterning are still unknown. Here, we mutate both copies of the transcription factor apterous in Bicyclus anynana butterflies using CRISPR/Cas9 and show that apterous A, expressed dorsally, functions both as a repressor and modifier of ventral wing colour patterns, as well as a promoter of dorsal sexual ornaments in males. We propose that the surface-specific diversification of wing patterns in butterflies proceeded via the co-option of apterous A or its downstream effectors into various gene regulatory networks involved in the differentiation of discrete wing traits. Further, interactions between apterous and sex-specific factors such as doublesex may have contributed to the origin of sexually dimorphic surface-specific patterns. Finally, we discuss the evolution of eyespot number diversity in the family Nymphalidae within the context of developmental constraints due to apterous regulation.

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