Juvenile hormone mediates sexual dimorphism in horned beetles

Shelby, J. A.; Madewell, Richard; Moczek, Armin P.

doi:10.1002/jez.b.21165

Cited by 36 publications

(27 citation statements)

References 35 publications

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“…Furthermore, comparative morphological studies have shown that head and thoracic horns in the same species can differ widely in the degree to which their development is affected by sex and nutrition, suggesting that sex-and nutrition-dependent horn development can diversify independently for different body regions (21,23,24,27). Taken together, our results paint an extraordinarily dynamic picture of dsx evolution and its role in the origin and diversification of sexual and male dimorphism in horned beetles.…”

Section: Resultsmentioning

confidence: 57%

Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns

Kijimoto

Moczek

Andrews

2012

Proc. Natl. Acad. Sci. U.S.A.

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167

198

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Sex-specific trait expression is frequently associated with highly variable, condition-dependent expression within sexes and rapid divergence among closely related species. Horned beetles are an excellent example for studying the molecular basis of these phenomena because horn morphology varies markedly among species, between sexes, and among alternative, nutritionally-cued morphs within sexes. In addition, horns lack obvious homology to other insect traits and provide a good opportunity to explore the molecular basis of the rapid diversification of a novel trait within and between species. Here we show that the sex-determination gene doublesex (dsx) underlies important aspects of horn development, including differences between sexes, morphs, and species. In male Onthophagus taurus, dsx transcripts were preferentially expressed in the horns of the large, horned morph, and RNAimediated knockdown of dsx dramatically altered male horn allometry by massively reducing horn development in large males, but not in smaller males. Conversely, dsx RNAi induced ectopic, nutrition-sensitive horn development in otherwise hornless females. Finally, in a closely related species (Onthophagus sagittarius) that has recently evolved a rare reversed sexual dimorphism, dsx RNAi revealed reversed as well as novel dsx functions despite an overall conservation of dsx expression. This suggests that rapid evolution of dsx functions has facilitated the transition from a regular sexual dimorphism to a reversed sexual dimorphism in this species. Our findings add beetle horns to existing examples of a close relationship between dsx and sexual trait development, and suggest that dsx function has been coopted to facilitate both the evolution of environmentally-cued intrasexual dimorphisms and rapid species divergences in a novel trait.cooption | polyphenism | evolutionary novelty | interchangeability | weak linkage

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Section: Resultsmentioning

confidence: 57%

Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns

Kijimoto

Moczek

Andrews

2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

167

198

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“…In addition, medium to high levels of the JH analog methoprene applied to the final instar of stalk-eyed flies results in a reduction or even a complete switch in the direction of SSD (from male-biased SSD to female-biased SSD) (63). Furthermore, several studies have shown that JH is important in creating dimorphism in beetle horns (42, 109). The results of these studies suggest that JH may play an important role in producing adult SSD, but the inconsistent results among studies indicate that much more work is needed before we will have an understanding of how and even if JH plays a role in producing SSD.…”

Section: Phenotypic Plasticity In Body Size In Insectsmentioning

confidence: 99%

Sex Differences in Phenotypic Plasticity Affect Variation in Sexual Size Dimorphism in Insects: From Physiology to Evolution

Stillwell

Blanckenhorn

Teder

et al. 2010

Annu. Rev. Entomol.

373

410

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Males and females of nearly all animals differ in their body size, a phenomenon called sexual size dimorphism (SSD). The degree and direction of SSD vary considerably among taxa, including among populations within species. A considerable amount of this variation is due to sex differences in body size plasticity. We examine how variation in these sex differences is generated by exploring sex differences in plasticity in growth rate and development time and the physiological regulation of these differences (e.g., sex differences in regulation by the endocrine system). We explore adaptive hypotheses proposed to explain sex differences in plasticity, including those that predict that plasticity will be lowest for traits under strong selection (adaptive canalization) or greatest for traits under strong directional selection (condition dependence), but few studies have tested these hypotheses. Studies that combine proximate and ultimate mechanisms offer great promise for understanding variation in SSD and sex differences in body size plasticity in insects.

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“…33 and 45-47) by using a residual analysis as detailed in ref. 48. We used two-tailed T tests to determine whether horn length residuals differed significantly across treatment groups.…”

mentioning

confidence: 99%

Differential recruitment of limb patterning genes during development and diversification of beetle horns

Moczek

Rose

2009

Proc. Natl. Acad. Sci. U.S.A.

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185

193

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The origins of novel complex phenotypes represent one of the most fundamental, yet largely unresolved, issues in evolutionary biology. Here we explore the developmental genetic regulation of beetle horns, a class of traits that lacks obvious homology to traits in other insects. Furthermore, beetle horns are remarkably diverse in their expression, including sexual dimorphisms, male dimorphisms, and interspecific differences in location of horn expression. At the same time, beetle horns share aspects of their development with that of more traditional appendages. We used larval RNA interference-mediated gene function analysis of 3 cardinal insect appendage patterning genes,dachshund, homothorax, and Distalless, to investigate their role in development and diversification of beetle horns within and between species. Transcript depletion of all 3 patterning genes generated phenotypic effects very similar to those documented in previous studies that focused on general insect development. In addition, we found that Distal-less and homothorax, but not dachshund, regulate horn expression in a species-, sex-, body region-, and body size-dependent manner. Our results demonstrate differential co-option of appendage patterning genes during the evolution and radiation of beetle horns. Furthermore, our results illustrate that regulatory genes whose functions are otherwise highly conserved nevertheless retain the capacity to acquire additional functions, and that little phylogenetic distance appears necessary for the evolution of sex-and species-specific differences in these functions.

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Juvenile hormone mediates sexual dimorphism in horned beetles

Cited by 36 publications

References 35 publications

Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns

Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns

Sex Differences in Phenotypic Plasticity Affect Variation in Sexual Size Dimorphism in Insects: From Physiology to Evolution

Differential recruitment of limb patterning genes during development and diversification of beetle horns

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