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Bell MA, Lim G, Caldwell C, Emlen DJ, Swanson BO. Rhinoceros beetle (Trypoxylus dichotomus) cuticular hydrocarbons contain information about body size and sex. PLoS One 2024; 19:e0299796. [PMID: 38483942 PMCID: PMC10939270 DOI: 10.1371/journal.pone.0299796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 02/15/2024] [Indexed: 03/17/2024] Open
Abstract
Japanese rhinoceros beetle (Trypoxylus dichotomus) males have exaggerated horns that are used to compete for territories. Larger males with larger horns tend to win these competitions, giving them access to females. Agonistic interactions include what appears to be assessment and often end without escalating to physical combat. However, it is unknown what information competitors use to assess each other. In many insect species chemical signals can carry a range of information, including social position, nutritional state, morphology, and sex. Specifically, cuticular hydrocarbons (CHCs), which are waxes excreted on the surface of insect exoskeletons, can communicate a variety of information. Here, we asked whether CHCs in rhinoceros beetles carry information about sex, body size, and condition that could be used by males during assessment behavior. Multivariate analysis of hydrocarbon composition revealed patterns associated with both sex and body size. We suggest that Rhinoceros beetles could be communicating information through CHCs that would explain behavioral decisions.
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Affiliation(s)
- Micah A. Bell
- Department of Biology, Gonzaga University, Spokane, Washington, United States of America
| | - Garrett Lim
- Department of Biology, Gonzaga University, Spokane, Washington, United States of America
| | - Chelsey Caldwell
- Division of Biological Sciences, The University of Montana, Missoula, Montana, United States of America
| | - Douglas J. Emlen
- Division of Biological Sciences, The University of Montana, Missoula, Montana, United States of America
| | - Brook O. Swanson
- Department of Biology, Gonzaga University, Spokane, Washington, United States of America
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2
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Weber JN, Kojima W, Boisseau RP, Niimi T, Morita S, Shigenobu S, Gotoh H, Araya K, Lin CP, Thomas-Bulle C, Allen CE, Tong W, Lavine LC, Swanson BO, Emlen DJ. Evolution of horn length and lifting strength in the Japanese rhinoceros beetle Trypoxylus dichotomus. Curr Biol 2023; 33:4285-4297.e5. [PMID: 37734374 DOI: 10.1016/j.cub.2023.08.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/28/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
What limits the size of nature's most extreme structures? For weapons like beetle horns, one possibility is a tradeoff associated with mechanical levers: as the output arm of the lever system-the beetle horn-gets longer, it also gets weaker. This "paradox of the weakening combatant" could offset reproductive advantages of additional increases in weapon size. However, in contemporary populations of most heavily weaponed species, males with the longest weapons also tend to be the strongest, presumably because selection drove the evolution of compensatory changes to these lever systems that ameliorated the force reductions of increased weapon size. Therefore, we test for biomechanical limits by reconstructing the stages of weapon evolution, exploring whether initial increases in weapon length first led to reductions in weapon force generation that were later ameliorated through the evolution of mechanisms of mechanical compensation. We describe phylogeographic relationships among populations of a rhinoceros beetle and show that the "pitchfork" shaped head horn likely increased in length independently in the northern and southern radiations of beetles. Both increases in horn length were associated with dramatic reductions to horn lifting strength-compelling evidence for the paradox of the weakening combatant-and these initial reductions to horn strength were later ameliorated in some populations through reductions to horn length or through increases in head height (the input arm for the horn lever system). Our results reveal an exciting geographic mosaic of weapon size, weapon force, and mechanical compensation, shedding light on larger questions pertaining to the evolution of extreme structures.
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Affiliation(s)
- Jesse N Weber
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Wataru Kojima
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan
| | - Romain P Boisseau
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Shuji Shigenobu
- Trans-Scale Biology Center, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Hiroki Gotoh
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, 836 Oya, Suruga Ward, Shizuoka, Japan
| | - Kunio Araya
- Faculty of Social and Cultural Studies, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-city Fukuoka 819-0395, Japan
| | - Chung-Ping Lin
- Department of Life Science, National Taiwan Normal University, No.88 Sec. 4, Tingzhou Rd, Taipei 11677, Taiwan
| | - Camille Thomas-Bulle
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA; Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Cerisse E Allen
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Wenfei Tong
- Cornell Laboratory of Ornithology, Ithaca, NY 14850, USA
| | - Laura Corley Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
| | - Brook O Swanson
- Department of Biology, Gonzaga University, 502 East Boone Avenue, Spokane, WA 99258-0102, USA
| | - Douglas J Emlen
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA.
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3
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Morita S, Shibata TF, Nishiyama T, Kobayashi Y, Yamaguchi K, Toga K, Ohde T, Gotoh H, Kojima T, Weber JN, Salvemini M, Bino T, Mase M, Nakata M, Mori T, Mori S, Cornette R, Sakura K, Lavine LC, Emlen DJ, Niimi T, Shigenobu S. The draft genome sequence of the Japanese rhinoceros beetle Trypoxylus dichotomus septentrionalis towards an understanding of horn formation. Sci Rep 2023; 13:8735. [PMID: 37253792 DOI: 10.1038/s41598-023-35246-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 05/15/2023] [Indexed: 06/01/2023] Open
Abstract
The Japanese rhinoceros beetle Trypoxylus dichotomus is a giant beetle with distinctive exaggerated horns present on the head and prothoracic regions of the male. T. dichotomus has been used as a research model in various fields such as evolutionary developmental biology, ecology, ethology, biomimetics, and drug discovery. In this study, de novo assembly of 615 Mb, representing 80% of the genome estimated by flow cytometry, was obtained using the 10 × Chromium platform. The scaffold N50 length of the genome assembly was 8.02 Mb, with repetitive elements predicted to comprise 49.5% of the assembly. In total, 23,987 protein-coding genes were predicted in the genome. In addition, de novo assembly of the mitochondrial genome yielded a contig of 20,217 bp. We also analyzed the transcriptome by generating 16 RNA-seq libraries from a variety of tissues of both sexes and developmental stages, which allowed us to identify 13 co-expressed gene modules. We focused on the genes related to horn formation and obtained new insights into the evolution of the gene repertoire and sexual dimorphism as exemplified by the sex-specific splicing pattern of the doublesex gene. This genomic information will be an excellent resource for further functional and evolutionary analyses, including the evolutionary origin and genetic regulation of beetle horns and the molecular mechanisms underlying sexual dimorphism.
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Grants
- 23128505, 25128706, 16H01452, 18H04766, 20H04933, 20H05944, 17H06384, 22128008, 19K16181, 21K15135 Japan Society for the Promotion of Science
- 23128505, 25128706, 16H01452, 18H04766, 20H04933, 20H05944, 17H06384, 22128008, 19K16181, 21K15135 Japan Society for the Promotion of Science
- 23128505, 25128706, 16H01452, 18H04766, 20H04933, 20H05944, 17H06384, 22128008, 19K16181, 21K15135 Japan Society for the Promotion of Science
- 23128505, 25128706, 16H01452, 18H04766, 20H04933, 20H05944, 17H06384, 22128008, 19K16181, 21K15135 Japan Society for the Promotion of Science
- IOS-1456133 National Science Foundation
- IOS-1456133 National Science Foundation
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Affiliation(s)
- Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Japan
| | - Tomoko F Shibata
- Division of Evolutionary Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Tomoaki Nishiyama
- Division of Integrated Omics Research, Research Center for Experimental Modeling of Human Disease, Kanazawa University, Kanazawa, Japan
| | - Yuuki Kobayashi
- Laboratory of Evolutionary Genomics, National Institute for Basic Biology, Okazaki, Japan
| | - Katsushi Yamaguchi
- Trans-Omics Facility, National Institute for Basic Biology, Okazaki, Japan
| | - Kouhei Toga
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- URA Division, Office of Research and Academia-Government-Community Collaboration, Hiroshima University, Hiroshima, Japan
| | - Takahiro Ohde
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Department of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Hiroki Gotoh
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Takaaki Kojima
- Laboratory of Molecular Biotechnology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Department of Agrobiological Resources, Faculty of Agriculture, Meijo University, Nagoya, Japan
| | - Jesse N Weber
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Marco Salvemini
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Takahiro Bino
- Trans-Omics Facility, National Institute for Basic Biology, Okazaki, Japan
| | - Mutsuki Mase
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Moe Nakata
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Tomoko Mori
- Trans-Omics Facility, National Institute for Basic Biology, Okazaki, Japan
| | - Shogo Mori
- Trans-Omics Facility, National Institute for Basic Biology, Okazaki, Japan
| | - Richard Cornette
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Kazuki Sakura
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Laura C Lavine
- Department of Entomology, Washington State University, Pullman, WA, USA
| | - Douglas J Emlen
- Division of Biological Sciences, The University of Montana, Missoula, MT, USA
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan.
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Japan.
- Laboratory of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
| | - Shuji Shigenobu
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Japan.
- Laboratory of Evolutionary Genomics, National Institute for Basic Biology, Okazaki, Japan.
- Trans-Omics Facility, National Institute for Basic Biology, Okazaki, Japan.
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4
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Kojima W. Temporal niche shifts driven by interference competition: Giant hornets exclude rhinoceros beetles at sap sites at dawn. Ecology 2023; 104:e3914. [PMID: 36336885 DOI: 10.1002/ecy.3914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/10/2022] [Accepted: 10/13/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Wataru Kojima
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan
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5
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Sakura K, Morita S, Niimi T. RNA Interference Method for Gene Function Analysis in the Japanese Rhinoceros Beetle Trypoxylus dichotomus. Bio Protoc 2022; 12:e4396. [PMID: 35800098 PMCID: PMC9081472 DOI: 10.21769/bioprotoc.4396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 12/20/2021] [Accepted: 03/14/2022] [Indexed: 12/29/2022] Open
Abstract
In the Japanese rhinoceros beetle Trypoxylus dichotomus, various candidate genes required for a specific phenotype of interest are listed by next-generation sequencing analysis. Their functions were investigated using RNA interference (RNAi) method, the only gene function analysis tool for T. dichotomusdeveloped so far. The summarized procedure for the RNAi method used for T. dichotomusis to synthesize double-stranded RNA (dsRNA), and inject it in larvae or pupae of T. dichotomus. Although some dedicated materials or equipment are generally required to inject dsRNA in insects, the advantage of the protocol described here is that it is possible to inject dsRNA in T. dichotomuswith one syringe.
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Affiliation(s)
- Kazuki Sakura
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
| | - Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan,Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Japan,*For correspondence:
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6
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Cirino LA, Lenga SH, Miller CW. Do males that experience weapon damage have greater reproductive potential than intact males in polygynous scenarios? Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03019-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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7
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Shibata R, Kojima W. An introduced host plant alters circadian activity patterns of a rhinoceros beetle. Ecology 2021; 102:e03366. [PMID: 33848368 DOI: 10.1002/ecy.3366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/02/2021] [Accepted: 02/22/2021] [Indexed: 11/10/2022]
Affiliation(s)
- Ryo Shibata
- Sugito Town Daisan Elementary School, 2777 Tsutsumine, Sugito-Town, Saitama, Japan
| | - Wataru Kojima
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-City, Yamaguchi, Japan
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8
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Emberts Z, Wiens JJ. Do sexually selected weapons drive diversification? Evolution 2021; 75:2411-2424. [PMID: 33738793 DOI: 10.1111/evo.14212] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/16/2021] [Accepted: 03/02/2021] [Indexed: 12/15/2022]
Abstract
Sexual selection is often thought to promote speciation. This expectation is largely driven by the fact that sexually selected traits can influence mating patterns and contribute to reproductive isolation. Indeed, some comparative studies have shown that clades with sexually selected traits have increased rates of speciation and diversification. However, these studies have almost exclusively focused on one mechanism of sexual selection: female choice. Another widespread mechanism is male-male competition. Few empirical studies (if any) have investigated the role of this alternative mechanism in driving diversification. Nevertheless, recent reviews have suggested that male-male competition can increase speciation rates. Here, we investigated whether traits associated with precopulatory male-male competition (i.e., sexually selected weapons) have promoted speciation and diversification in insects. We focused on three clades with both weapons and suitable phylogenies: leaf-footed and broad-headed bugs (Coreidae+Alydidae; ∼2850 species), stick insects and relatives (Phasmatodea; ∼3284 species), and scarab beetles (Scarabaeoidea; ∼39,717 species). We found no evidence that weapon-bearing lineages in these clades have higher rates of speciation or diversification than their weaponless relatives. Thus, our results suggest that precopulatory male-male competition may not have strong, general effects on speciation and diversification in insects, a group encompassing ∼60% of all described species.
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Affiliation(s)
- Zachary Emberts
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, 85721
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, 85721
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9
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Is Allometric Variation in the Cephalic Horn on Male Rhinoceros Beetles Discontinuously Dimorphic? Evol Biol 2021. [DOI: 10.1007/s11692-021-09533-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Abstract
Many sexually selected traits function as weapons, and these weapons can be incredibly diverse. However, the factors underlying weapon diversity among species remain poorly understood, and a fundamental hypothesis to explain this diversity remains untested. Although weapons can serve multiple functions, an undeniably important function is their role in fights. Thus, a crucial hypothesis is that weapon diversification is driven by the evolution of weapon modifications that provide an advantage in combat (e.g. causing more damage). Here, we test this fighting-advantage hypothesis using data from 17 species of coreid bugs. We utilize the fact that male-male combat in coreids often results in detectable damage, allowing us to link different weapon morphologies to different levels of damage among species. We find that certain weapon morphologies inflict much more damage than others, strongly supporting the fighting-advantage hypothesis. Moreover, very different weapon morphologies can inflict similarly severe amounts of damage, leading to a weapon performance landscape with multiple performance peaks. This multi-peak pattern could potentially drive different lineages towards divergent weapon forms, further increasing weapon diversity among species. Overall, our results may help explain how sexually selected weapons have evolved into the diversity of forms seen today.
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Affiliation(s)
- Zachary Emberts
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721-0088, USA
| | - Wei Song Hwang
- Lee Kong Chian Natural History Museum, National University of Singapore, 2 Conservatory Drive, Singapore 117377, Singapore
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721-0088, USA
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11
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Del Sol JF, Hongo Y, Boisseau RP, Berman GH, Allen CE, Emlen DJ. Population differences in the strength of sexual selection match relative weapon size in the Japanese rhinoceros beetle, Trypoxylus dichotomus (Coleoptera: Scarabaeidae)†. Evolution 2020; 75:394-413. [PMID: 33009663 DOI: 10.1111/evo.14101] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 07/07/2020] [Accepted: 09/07/2020] [Indexed: 12/21/2022]
Abstract
Exaggerated weapons of sexual selection often diverge more rapidly and dramatically than other body parts, suggesting that relevant agents of selection may be discernible in contemporary populations. We examined the ecology, reproductive behavior, and strength of sexual selection on horn length in five recently diverged rhinoceros beetle (Trypoxylus dichotomus) populations that differ in relative horn size. Males with longer horns were better at winning fights in all locations, but the link between winning fights and mating success differed such that selection favored large males with long horns at the two long-horned populations, but was relaxed or nonexistent at the populations with relatively shorter horns. Observations of local habitat conditions and breeding ecology point to shifts in the relative abundance of feeding territories as the most likely cause of population differences in selection on male weapon size in this species. Comparisons of ecological conditions and selection strength across populations offer critical first steps toward meaningfully linking mating system dynamics, selection patterns, and diversity in sexually selected traits.
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Affiliation(s)
- Jillian F Del Sol
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
| | - Yoshihito Hongo
- Department of Life Sciences, Ritsumeikan University, Kyoto, 603-8577, Japan
| | - Romain P Boisseau
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
| | - Gabriella H Berman
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
| | - Cerisse E Allen
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
| | - Douglas J Emlen
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812
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12
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Lavine MD, Gotoh H, Hayes A, Corley Lavine L. The Insulin Signaling Substrate Chico and the Ecdysone Response Element Broad Both Regulate Growth of the Head Horns in the Asian Rhinoceros Beetle, Trypoxylus dichotomus. Integr Comp Biol 2019; 59:1338-1345. [PMID: 31165143 DOI: 10.1093/icb/icz093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Males of the Asian rhinoceros beetle, Trypoxylus dichotomus, possess exaggerated head and thoracic horns that scale dramatically out of proportion to body size. While RNAi-mediated knockdowns of the insulin receptor suggest that the insulin signaling pathway regulates nutrition-dependent growth including exaggerated horns, the genes that regulate disproportionate growth have yet to be identified. We used RNAi-mediated knockdown of several genes to investigate their potential role in growth and scaling of the sexually dimorphic, exaggerated head horns of T. dichotomus. Knockdown of the insulin signaling substrate chico and the ecdysone response element broad caused significant decreases in head horn length, while having no or minimal effects on other structures such as elytra and tibiae. However, scaling of horns to body size was not affected by either knockdown. In addition, knockdown of phosphatase and tensin homolog, a negative regulator of the insulin signaling pathway, had no significant effects on any trait. Our results do not identify any candidate genes that may specifically mediate the allometric aspect of horn growth, but they do confirm the insulin signaling pathway as a mediator of conditional trait expression, and importantly implicate the ecdysone signaling pathway, possibly in conjunction with insulin signaling, as an additional mediator of horn growth.
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Affiliation(s)
- Mark D Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
| | - Hiroki Gotoh
- Faculty of Environmental Earth Sciences, Hokkaido University, Sapporo, Hokkaido 0600810, Japan
| | - Abigail Hayes
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
| | - Laura Corley Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, USA
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13
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Variation in an Extreme Weapon: Horn Performance Differences across Rhinoceros Beetle ( Trypoxylus dichotomus) Populations. INSECTS 2019; 10:insects10100346. [PMID: 31618906 PMCID: PMC6835817 DOI: 10.3390/insects10100346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 01/02/2023]
Abstract
Japanese rhinoceros beetle (Trypoxylus dichotomus) males have exaggerated head horns that they use as weapons in combat over reproductive opportunities. In these contests, there is an advantage to having a longer horn, and there seems to be little cost to horn exaggeration. However, populations vary in the amount of horn exaggeration across this widespread species. Here, we examine four populations and quantify scaling and functional morphology of the horn. We then measure force production by the horn system in a combat-relevant movement. We find that not only does horn length vary among populations, but allometry of lever mechanics and force production varies in a complex way. For instance, some beetle populations make relatively long horns, but exert relatively low forces. Other populations make shorter horns and produce higher forces during fights. We suggest that this performance variation could be associated with differences in the intensity or type of sexual selection across the species.
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14
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Zinna R, Emlen D, Lavine LC, Johns A, Gotoh H, Niimi T, Dworkin I. Sexual dimorphism and heightened conditional expression in a sexually selected weapon in the Asian rhinoceros beetle. Mol Ecol 2018; 27:5049-5072. [PMID: 30357984 DOI: 10.1111/mec.14907] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 12/12/2022]
Abstract
Among the most dramatic examples of sexual selection are the weapons used in battles between rival males over access to females. As with ornaments of female choice, the most "exaggerated" sexually selected weapons vary from male to male more widely than other body parts (hypervariability), and their growth tends to be more sensitive to nutritional state or physiological condition compared with growth of other body parts ("heightened" conditional expression). Here, we use RNAseq analysis to build on recent work exploring these mechanisms in the exaggerated weapons of beetles, by examining patterns of differential gene expression in exaggerated (head and thorax horns) and non-exaggerated (wings, genitalia) traits in the Asian rhinoceros beetle, Trypoxylus dichotomus. Our results suggest that sexually dimorphic expression of weaponry involves large-scale changes in gene expression, relative to other traits, while nutrition-driven changes in gene expression in these same weapons are less pronounced. However, although fewer genes overall were differentially expressed in high- vs. low-nutrition individuals, the number of differentially expressed genes varied predictably according to a trait's degree of condition dependence (head horn > thorax horn > wings > genitalia). Finally, we observed a high degree of similarity in direction of effects (vectors) for subsets of differentially expressed genes across both sexually dimorphic and nutritionally responsive growth. Our results are consistent with a common set of mechanisms governing sexual size dimorphism and condition dependence.
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Affiliation(s)
- Robert Zinna
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Douglas Emlen
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Laura C Lavine
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Annika Johns
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Hiroki Gotoh
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Teruyuki Niimi
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Ian Dworkin
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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15
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Eberhard WG, Rodríguez RL, Huber BA, Speck B, Miller H, Buzatto BA, Machado G. Sexual Selection and Static Allometry: The Importance of Function. QUARTERLY REVIEW OF BIOLOGY 2018. [DOI: 10.1086/699410] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Hust J, Lavine MD, Worthington AM, Zinna R, Gotoh H, Niimi T, Lavine L. The Fat-Dachsous signaling pathway regulates growth of horns in Trypoxylus dichotomus, but does not affect horn allometry. JOURNAL OF INSECT PHYSIOLOGY 2018; 105:85-94. [PMID: 29366850 DOI: 10.1016/j.jinsphys.2018.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 06/07/2023]
Abstract
Males of the Asian rhinoceros beetle, Trypoxylus dichotomus, possess exaggerated head and thoracic horns that scale dramatically out of proportion to body size. While studies of insulin signaling suggest that this pathway regulates nutrition-dependent growth including exaggerated horns, what regulates disproportionate growth has yet to be identified. The Fat signaling pathway is a potential candidate for regulating disproportionate growth of sexually-selected traits, a hypothesis we advanced in a previous paper (Gotoh et al., 2015). To investigate the role of Fat signaling in the growth and scaling of the sexually dimorphic, condition-dependent traits of the in the Asian rhinoceros beetle T. dichotomus, we used RNA interference to knock down expression of fat and its co-receptor dachsous. Knockdown of fat, and to a lesser degree dachsous, caused shortening and widening of appendages, including the head and thoracic horns. However, scaling of horns to body size was not affected. Our results show that Fat signaling regulates horn growth in T. dichotomus as it does in appendage growth in other insects. However, we provide evidence that Fat signaling does not mediate the disproportionate, positive allometric growth of horns in T. dichotomus.
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Affiliation(s)
- James Hust
- Department of Entomology, Washington State University, Pullman, WA 99164, United States
| | - Mark D Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, United States
| | - Amy M Worthington
- Department of Entomology, Washington State University, Pullman, WA 99164, United States
| | - Robert Zinna
- Department of Entomology, Washington State University, Pullman, WA 99164, United States
| | - Hiroki Gotoh
- Department of Entomology, Washington State University, Pullman, WA 99164, United States; Lab of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - T Niimi
- Lab of Sericulture and Entomoresources, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan; Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - Laura Lavine
- Department of Entomology, Washington State University, Pullman, WA 99164, United States.
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Emlen DJ. ARTIFICIAL SELECTION ON HORN LENGTH‐BODY SIZE ALLOMETRY IN THE HORNED BEETLE
ONTHOPHAGUS ACUMINATUS
(COLEOPTERA: SCARABAEIDAE). Evolution 2017; 50:1219-1230. [DOI: 10.1111/j.1558-5646.1996.tb02362.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/1994] [Accepted: 05/30/1995] [Indexed: 11/29/2022]
Affiliation(s)
- Douglas J. Emlen
- Department of Ecology and Evolutionary Biology Princeton University Princeton New Jersey 08544‐1003
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18
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del Castillo RC, Núñez-Farfán J. SEXUAL SELECTION ON MATURATION TIME AND BODY SIZE INSPHENARIUM PURPURASCENS(ORTHOPTERA: PYRGOMORPHIDAE): CORRELATED RESPONSE TO SELECTION. Evolution 2017; 53:209-215. [DOI: 10.1111/j.1558-5646.1999.tb05346.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/1998] [Accepted: 10/07/1998] [Indexed: 11/30/2022]
Affiliation(s)
- Raúl Cueva del Castillo
- Departamento de Ecología Evolutiva, Instituto de Ecología; Universidad Nacional Autónoma de México; Apartado Postal 70-275, México 04510, D.F. México
| | - J. Núñez-Farfán
- Departamento de Ecología Evolutiva, Instituto de Ecología; Universidad Nacional Autónoma de México; Apartado Postal 70-275, México 04510, D.F. México
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19
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Affiliation(s)
- Desh D. Chaudhary
- Ladybird Research Laboratory; Department of Zoology; University of Lucknow; Lucknow Uttar Pradesh India
| | - Geetanjali Mishra
- Ladybird Research Laboratory; Department of Zoology; University of Lucknow; Lucknow Uttar Pradesh India
| | - Omkar
- Ladybird Research Laboratory; Department of Zoology; University of Lucknow; Lucknow Uttar Pradesh India
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20
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Kojima W, Lin CP. It takes two to tango: functional roles, sexual selection and allometry of multiple male weapons in the flower beetle Dicronocephalus wallichii bourgoini. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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21
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Zinna R, Gotoh H, Brent CS, Dolezal A, Kraus A, Niimi T, Emlen D, Lavine LC. Endocrine Control of Exaggerated Trait Growth in Rhinoceros Beetles. Integr Comp Biol 2016; 56:247-59. [PMID: 27252223 DOI: 10.1093/icb/icw042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Juvenile hormone (JH) is a key insect growth regulator frequently involved in modulating phenotypically plastic traits such as caste determination in eusocial species, wing polymorphisms in aphids, and mandible size in stag beetles. The jaw morphology of stag beetles is sexually-dimorphic and condition-dependent; males have larger jaws than females and those developing under optimum conditions are larger in overall body size and have disproportionately larger jaws than males raised under poor conditions. We have previously shown that large males have higher JH titers than small males during development, and ectopic application of fenoxycarb (JH analog) to small males can induce mandibular growth similar to that of larger males. What remains unknown is whether JH regulates condition-dependent trait growth in other insects with extreme sexually selected structures. In this study, we tested the hypothesis that JH mediates the condition-dependent expression of the elaborate horns of the Asian rhinoceros beetle, Trypoxylus dichotomus. The sexually dimorphic head horn of this beetle is sensitive to nutritional state during larval development. Like stag beetles, male rhinoceros beetles receiving copious food produce disproportionately large horns for their body size compared with males under restricted diets. We show that JH titers are correlated with body size during the late feeding and early prepupal periods, but this correlation disappears by the late prepupal period, the period of maximum horn growth. While ectopic application of fenoxycarb during the third larval instar significantly delayed pupation, it had no effect on adult horn size relative to body size. Fenoxycarb application to late prepupae also had at most a marginal effect on relative horn size. We discuss our results in context of other endocrine signals of condition-dependent trait exaggeration and suggest that different beetle lineages may have co-opted different physiological signaling mechanisms to achieve heightened nutrient-sensitive weapon growth.
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Affiliation(s)
- R Zinna
- *Department of Entomology, Washington State University, Pullman, WA 99164 USA
| | - H Gotoh
- **Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - C S Brent
- U.S. Department of Agriculture, Arid-Land Agricultural Research Center, Maricopa, AZ 85138 USA
| | - A Dolezal
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - A Kraus
- Department of Biology, Gonzaga University, Spokane, WA 99258 USA
| | - T Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi 444-8585, Japan
| | - D Emlen
- Division of Biological Sciences, University of Montana-Missoula, Missoula, MT 59812, USA
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22
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Eldred T, Meloro C, Scholtz C, Murphy D, Fincken K, Hayward M. Does size matter for horny beetles? A geometric morphometric analysis of interspecific and intersexual size and shape variation in Colophon haughtoni Barnard, 1929, and C. kawaii Mizukami, 1997 (Coleoptera: Lucanidae). ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0289-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Gotoh H, Zinna RA, Warren I, DeNieu M, Niimi T, Dworkin I, Emlen DJ, Miura T, Lavine LC. Identification and functional analyses of sex determination genes in the sexually dimorphic stag beetle Cyclommatus metallifer. BMC Genomics 2016; 17:250. [PMID: 27001106 PMCID: PMC4802893 DOI: 10.1186/s12864-016-2522-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 02/24/2016] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Genes in the sex determination pathway are important regulators of sexually dimorphic animal traits, including the elaborate and exaggerated male ornaments and weapons of sexual selection. In this study, we identified and functionally analyzed members of the sex determination gene family in the golden metallic stag beetle Cyclommatus metallifer, which exhibits extreme differences in mandible size between males and females. RESULTS We constructed a C. metallifer transcriptomic database from larval and prepupal developmental stages and tissues of both males and females. Using Roche 454 pyrosequencing, we generated a de novo assembled database from a total of 1,223,516 raw reads, which resulted in 14,565 isotigs (putative transcript isoforms) contained in 10,794 isogroups (putative identified genes). We queried this database for C. metallifer conserved sex determination genes and identified 14 candidate sex determination pathway genes. We then characterized the roles of several of these genes in development of extreme sexual dimorphic traits in this species. We performed molecular expression analyses with RT-PCR and functional analyses using RNAi on three C. metallifer candidate genes--Sex-lethal (CmSxl), transformer-2 (Cmtra2), and intersex (Cmix). No differences in expression pattern were found between the sexes for any of these three genes. In the RNAi gene-knockdown experiments, we found that only the Cmix had any effect on sexually dimorphic morphology, and these mimicked the effects of Cmdsx knockdown in females. Knockdown of CmSxl had no measurable effects on stag beetle phenotype, while knockdown of Cmtra2 resulted in complete lethality at the prepupal period. These results indicate that the roles of CmSxl and Cmtra2 in the sex determination cascade are likely to have diverged in stag beetles when compared to Drosophila. Our results also suggest that Cmix has a conserved role in this pathway. In addition to those three genes, we also performed a more complete functional analysis of the C. metallifer dsx gene (Cmdsx) to identify the isoforms that regulate dimorphism more fully using exon-specific RNAi. We identified a total of 16 alternative splice variants of the Cmdsx gene that code for up to 14 separate exons. Despite the variation in RNA splice products of the Cmdsx gene, only four protein isoforms are predicted. The results of our exon-specific RNAi indicated that the essential CmDsx isoform for postembryonic male differentiation is CmDsxB, whereas postembryonic female specific differentiation is mainly regulated by CmDsxD. CONCLUSIONS Taken together, our results highlight the importance of studying the function of highly conserved sex determination pathways in numerous insect species, especially those with dramatic and exaggerated sexual dimorphism, because conservation in protein structure does not always translate into conservation in downstream function.
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Affiliation(s)
- Hiroki Gotoh
- Department of Entomology, Washington State University, Pullman, WA, 99164, USA
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Robert A Zinna
- Department of Entomology, Washington State University, Pullman, WA, 99164, USA
| | - Ian Warren
- Department of Entomology, Washington State University, Pullman, WA, 99164, USA
| | - Michael DeNieu
- Department of Zoology, Michigan State University, East Lansing, MI, 48824, USA
| | - Teruyuki Niimi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, 444-8585, Japan
| | - Ian Dworkin
- Department of Zoology, Michigan State University, East Lansing, MI, 48824, USA
- Department of Biology, McMaster University, Hamilton, ONT, L8S 4K1, Canada
| | - Douglas J Emlen
- Division of Biological Sciences, University of Montana-Missoula, Missoula, MT, 59812, USA
| | - Toru Miura
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
| | - Laura C Lavine
- Department of Entomology, Washington State University, Pullman, WA, 99164, USA.
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24
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Niu L, Gao J, Li H, Liu J, Yin W. Novel skeleton compound Allomyrinanoid A and two purine alkaloids from the adult of Allomyrina dichotoma L. Bioorg Med Chem Lett 2016; 26:366-369. [PMID: 26706167 DOI: 10.1016/j.bmcl.2015.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 11/12/2015] [Accepted: 12/04/2015] [Indexed: 11/16/2022]
Abstract
Three new compounds were isolated from the adult insect of Allomyrina dichotoma L. for the first time. A new skeleton compound is named as Allomyrinanoid A (1) originated from the familiar norbornane derivatives and two new compounds of purine alkaloid are named as adenine-9-methylaldehyde oxime B (2) and 6-N-methyleneimine-adenine-9-methylaldehyde oxime B (3). The compounds (2) and (3) are the tautomers of imine-enamine and creatively separated form the solvent using column chromatography method. The structures of all isolated compounds were established by spectroscopic methods including analyses of their 1D, 2D NMR and HRESI-MS data, and confirmed by comparison of the literature data. These new components displayed antibacterial activities against both Gram-positive and Gram-negative strain.
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Affiliation(s)
- Lanlan Niu
- School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471023, PR China.
| | - Jiayu Gao
- School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471023, PR China.
| | - Haidi Li
- School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471023, PR China.
| | - Junna Liu
- School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471023, PR China.
| | - Weiping Yin
- School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, Henan 471023, PR China.
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25
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McCullough EL, Ledger KJ, O'Brien DM, Emlen DJ. Variation in the allometry of exaggerated rhinoceros beetle horns. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.08.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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McCullough EL, Ledger KJ, Moore TY. Variation in cross-sectional horn shape within and among rhinoceros beetle species. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12557] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Erin L. McCullough
- Division of Biological Sciences; University of Montana; Missoula MT 59812 USA
- Centre for Evolutionary Biology; University of Western Australia; Crawley WA 6009 Australia
| | - Kimberly J. Ledger
- Division of Biological Sciences; University of Montana; Missoula MT 59812 USA
| | - Talia Y. Moore
- Department of Organismic and Evolutionary Biology; Harvard University; Concord Field Station Bedford MA 01730 USA
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27
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McCullough EL. Mechanical limits to maximum weapon size in a giant rhinoceros beetle. Proc Biol Sci 2015; 281:rspb.2014.0696. [PMID: 24827447 DOI: 10.1098/rspb.2014.0696] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The horns of giant rhinoceros beetles are a classic example of the elaborate morphologies that can result from sexual selection. Theory predicts that sexual traits will evolve to be increasingly exaggerated until survival costs balance the reproductive benefits of further trait elaboration. In Trypoxylus dichotomus, long horns confer a competitive advantage to males, yet previous studies have found that they do not incur survival costs. It is therefore unlikely that horn size is limited by the theoretical cost-benefit equilibrium. However, males sometimes fight vigorously enough to break their horns, so mechanical limits may set an upper bound on horn size. Here, I tested this mechanical limit hypothesis by measuring safety factors across the full range of horn sizes. Safety factors were calculated as the ratio between the force required to break a horn and the maximum force exerted on a horn during a typical fight. I found that safety factors decrease with increasing horn length, indicating that the risk of breakage is indeed highest for the longest horns. Structural failure of oversized horns may therefore oppose the continued exaggeration of horn length driven by male-male competition and set a mechanical limit on the maximum size of rhinoceros beetle horns.
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Affiliation(s)
- Erin L McCullough
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
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28
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Structural adaptations to diverse fighting styles in sexually selected weapons. Proc Natl Acad Sci U S A 2014; 111:14484-8. [PMID: 25201949 DOI: 10.1073/pnas.1409585111] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The shapes of sexually selected weapons differ widely among species, but the drivers of this diversity remain poorly understood. Existing explanations suggest weapon shapes reflect structural adaptations to different fighting styles, yet explicit tests of this hypothesis are lacking. We constructed finite element models of the horns of different rhinoceros beetle species to test whether functional specializations for increased performance under species-specific fighting styles could have contributed to the diversification of weapon form. We find that horns are both stronger and stiffer in response to species-typical fighting loads and that they perform more poorly under atypical fighting loads, which suggests weapons are structurally adapted to meet the functional demands of fighting. Our research establishes a critical link between weapon form and function, revealing one way male-male competition can drive the diversification of animal weapons.
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29
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Johns A, Gotoh H, McCullough EL, Emlen DJ, Lavine LC. Heightened condition-dependent growth of sexually selected weapons in the rhinoceros beetle, Trypoxylus dichotomus (Coleoptera: Scarabaeidae). Integr Comp Biol 2014; 54:614-21. [PMID: 24827150 DOI: 10.1093/icb/icu041] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The exaggerated weapons and ornaments of sexual selection are condition-dependent traits that often grow to exaggerated proportions. The horns of male rhinoceros beetles are extremely sensitive to the larval nutritional environment and are used by rival males in combat over access to females. In contrast to horns, other parts of the body, such as wings, eyes, and legs, scale proportionally with body size, whereas others, such as males' external genitalia, are invariant with body size, regardless of nutrition. We document how body parts of the Asian rhinoceros beetle, Trypoxylus dichotomus, exhibit plasticity and constraint in response to nutritional condition. We discuss the implications of these results for the evolution of condition-dependent and condition-independent traits in animals.
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Affiliation(s)
- A Johns
- *Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA; Department of Entomology, Washington State University, Pullman, WA 99164-6382, USA
| | - H Gotoh
- *Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA; Department of Entomology, Washington State University, Pullman, WA 99164-6382, USA
| | - E L McCullough
- *Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA; Department of Entomology, Washington State University, Pullman, WA 99164-6382, USA
| | - D J Emlen
- *Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA; Department of Entomology, Washington State University, Pullman, WA 99164-6382, USA
| | - L C Lavine
- *Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA; Department of Entomology, Washington State University, Pullman, WA 99164-6382, USA
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30
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Kojima W, Sugiura S, Makihara H, Ishikawa Y, Takanashi T. Rhinoceros beetles suffer male-biased predation by mammalian and avian predators. Zoolog Sci 2014; 31:109-15. [PMID: 24601771 DOI: 10.2108/zsj.31.109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Male sexually-selected traits often impose an increased risk of predation on their bearers, causing male-biased predation. We investigated whether males of the sap-feeding Japanese rhinoceros beetle Trypoxylus dichotomus were more susceptible to predation than females by comparing the morphology of beetles caught in bait traps with the remains of beetles found on the ground. The males of this species are larger than the females and have a horn on the head. We found that predation pressure was greater for males than for females, and that larger individuals of both sexes were more vulnerable to predation. We identified two predators, the raccoon dog Nyctereutes procyonoides and jungle crow Corvus macrorhynchos, by monitoring sap-site trees with infrared video cameras. Raccoon dogs visited sap-site trees at night, while crows came after daybreak. The highest frequency of visits by both predators was observed in the first half of August, which matches the peak season of T. dichotomus. Raccoon dogs often left bite marks on the remains of prey, whereas crows did not. Bite marks were found on most of the remains collected at two distant localities, which suggested that predation by raccoon dogs is common. Size- and sex-dependent differences in the conspicuousness and active period of T. dichotomus probably explain these biased predation patterns. Our results suggest that having a large horn/body is costly in terms of the increased risk of predation. Predation cost may act as a stabilizing selection pressure against the further exaggeration of male sexual traits.
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Affiliation(s)
- Wataru Kojima
- 1 Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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31
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Vieira MC, Peixoto PEC. Winners and losers: a meta‐analysis of functional determinants of fighting ability in arthropod contests. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12051] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marcos C. Vieira
- Departamento de Biologia Universidade Federal do Ceará Ceará Brazil
| | - Paulo E. C. Peixoto
- Departamento de Ciências Biológicas Universidade Estadual de Feira de Santana Feira de Santana CEP 44031‐460 Bahia Brazil
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33
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McCullough EL, Tobalske BW. Elaborate horns in a giant rhinoceros beetle incur negligible aerodynamic costs. Proc Biol Sci 2013; 280:20130197. [PMID: 23486444 DOI: 10.1098/rspb.2013.0197] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sexually selected ornaments and weapons are among nature's most extravagant morphologies. Both ornaments and weapons improve a male's reproductive success; yet, unlike ornaments that need only attract females, weapons must be robust and functional structures because they are frequently tested during male-male combat. Consequently, weapons are expected to be particularly costly to bear. Here, we tested the aerodynamic costs of horns in the giant rhinoceros beetle, Trypoxylus dichotomus. We predicted that the long, forked head horn would have three main effects on flight performance: increased body mass, an anterior shift in the centre of mass and increased body drag. We found that the horns were surprisingly lightweight, and therefore had a trivial effect on the male beetles' total mass and mass distribution. Furthermore, because beetles typically fly at slow speeds and high body angles, horns had little effect on total body drag. Together, the weight and the drag of horns increased the overall force required to fly by less than 3 per cent, even in the largest males. Because low-cost structures are expected to be highly evolutionarily labile, the fact that horns incur very minor flight costs may have permitted both the elaboration and diversification of rhinoceros beetle horns.
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Affiliation(s)
- Erin L McCullough
- Division of Biological Sciences, University of Montana, Missoula, MT, USA.
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34
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Effect of morph types, body size and prior residence on food-site holding by males of the male-dimorphic stag beetle Prosopocoilus inclinatus (Coleoptera: Lucanidae). J ETHOL 2012. [DOI: 10.1007/s10164-012-0350-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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35
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Hongo Y. Mating interaction of the Japanese horned beetle Trypoxylus dichotomus septentrionalis: does male-excluding behavior induce female resistance? Acta Ethol 2012. [DOI: 10.1007/s10211-012-0128-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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36
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Rojas R, Morales MC, Rivadeneira MM, Thiel M. Male morphotypes in the Andean river shrimp Cryphiops caementarius (Decapoda: Caridea): morphology, coloration and injuries. J Zool (1987) 2012. [DOI: 10.1111/j.1469-7998.2012.00922.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. Rojas
- Facultad de Ciencias del Mar; Universidad Católica del Norte; Coquimbo; Chile
| | - M. C. Morales
- Facultad de Ciencias del Mar; Universidad Católica del Norte; Coquimbo; Chile
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37
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McCullough EL, Weingarden PR, Emlen DJ. Costs of elaborate weapons in a rhinoceros beetle: how difficult is it to fly with a big horn? Behav Ecol 2012. [DOI: 10.1093/beheco/ars069] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Valena S, Moczek AP. Epigenetic mechanisms underlying developmental plasticity in horned beetles. GENETICS RESEARCH INTERNATIONAL 2012; 2012:576303. [PMID: 22567393 PMCID: PMC3335661 DOI: 10.1155/2012/576303] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 12/05/2011] [Indexed: 11/18/2022]
Abstract
All developmental plasticity arises through epigenetic mechanisms. In this paper we focus on the nature, origins, and consequences of these mechanisms with a focus on horned beetles, an emerging model system in evolutionary developmental genetics. Specifically, we introduce the biological significance of developmental plasticity and summarize the most important facets of horned beetle biology. We then compare and contrast the epigenetic regulation of plasticity in horned beetles to that of other organisms and discuss how epigenetic mechanisms have facilitated innovation and diversification within and among taxa. We close by highlighting opportunities for future studies on the epigenetic regulation of plastic development in these and other organisms.
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Affiliation(s)
- Sophie Valena
- Department of Biology, Indiana University, 915 E Third Street, Myers Hall 150, Bloomington, IN 47405-7107, USA
| | - Armin P. Moczek
- Department of Biology, Indiana University, 915 E Third Street, Myers Hall 150, Bloomington, IN 47405-7107, USA
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Ownership, size and reproductive status affect the outcome of food ball contests in a dung roller beetle: when do enemies share? Evol Ecol 2010. [DOI: 10.1007/s10682-010-9428-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Okada K, Miyatake T. Plasticity of size and allometry in multiple sexually selected traits in an armed beetle Gnatocerus cornutus. Evol Ecol 2010. [DOI: 10.1007/s10682-010-9370-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Okada K, Miyatake T. Genetic correlations between weapons, body shape and fighting behaviour in the horned beetle Gnatocerus cornutus. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2009.01.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Moczek AP. Chapter 6. The origin and diversification of complex traits through micro- and macroevolution of development: insights from horned beetles. Curr Top Dev Biol 2009; 86:135-62. [PMID: 19361692 DOI: 10.1016/s0070-2153(09)01006-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Understanding how development and ecology shape organismal evolution is a central goal of evolutionary developmental biology. This chapter highlights a class of traits and organisms that are emerging as new models in evo-devo and eco-devo research: beetle horns and horned beetles. Horned beetles are morphologically diverse, ecologically rich, and developmentally and genetically increasingly accessible. Recent studies have begun to take advantage of these attributes and are starting to link the microevolution of horned beetle development to the macroevolution of novel features, and to identify the genetic, developmental, and ecological mechanisms, and the interactions between them, that mediate organismal innovation and diversification in natural populations. Here, I review the most significant recent findings and their contributions to current frontiers in evolutionary developmental biology.
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Affiliation(s)
- Armin P Moczek
- Department of Biology, Indiana University, Bloomington, IN, USA
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Moczek, Emlen. Proximate determination of male horn dimorphism in the beetle Onthophagus taurus (Coleoptera: Scarabaeidae). J Evol Biol 2008. [DOI: 10.1046/j.1420-9101.1999.00004.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Moczek
- Lehrstuhl Zoologie II, Theodor‐Boveri‐Biozentrum der Universität, Am Hubland, Würzburg, Germany
- Department of Zoology, Duke University, Box 90325, North Carolina 27708–0325, USA
| | - Emlen
- Department of Zoology, Duke University, Box 90325, North Carolina 27708–0325, USA
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Pizzo A, Roggero A, Palestrini C, Moczek AP, Rolando A. Rapid shape divergences between natural and introduced populations of a horned beetle partly mirror divergences between species. Evol Dev 2008; 10:166-75. [DOI: 10.1111/j.1525-142x.2008.00224.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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HANLEY RODNEYS. Mandibular allometry and male dimorphism in a group of obligately mycophagous beetles (Insecta: Coleoptera: Staphylinidae: Oxyporinae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2001.tb01330.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Relations between allometry, male–male interactions and dispersal in a sap beetle, Librodor japonicus. Anim Behav 2007. [DOI: 10.1016/j.anbehav.2006.09.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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48
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Hongo Y. Evolution of male dimorphic allometry in a population of the Japanese horned beetle Trypoxylus dichotomus septentrionalis. Behav Ecol Sociobiol 2007. [DOI: 10.1007/s00265-007-0459-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Emlen DJ, Hunt J, Simmons LW. Evolution of sexual dimorphism and male dimorphism in the expression of beetle horns: phylogenetic evidence for modularity, evolutionary lability, and constraint. Am Nat 2007; 166 Suppl 4:S42-68. [PMID: 16224711 DOI: 10.1086/444599] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Beetle horns are enlarged outgrowths of the head or thorax that are used as weapons in contests over access to mates. Horn development is typically confined to males (sexual dimorphism) and often only to the largest males (male dimorphism). Both types of dimorphism result from endocrine threshold mechanisms that coordinate cell proliferation near the end of the larval period. Here, we map the presence/absence of each type of dimorphism onto a recent phylogeny for the genus Onthophagus (Coleoptera: Scarabaeidae) to explore how horn development has changed over time. Our results provide empirical support for several recent predictions regarding the evolutionary lability of developmental thresholds, including uncoupled evolution of alternative phenotypes and repeated fixation of phenotypes. We also report striking evidence of a possible developmental constraint. We show that male dimorphism and sexual dimorphism map together on the phylogeny; whenever small males have horns, females also have horns (and vice versa). We raise the possibility that correlated evolution of these two phenomena results from a shared element in their endocrine regulatory mechanisms rather than a history of common selection pressures. These results illustrate the type of insight that can be gained only from the integration of developmental and evolutionary perspectives.
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Affiliation(s)
- Douglas J Emlen
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA.
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Ownership-dependent mating tactics of minor males of the beetle Librodor japonicus (Nitidulidae) with intra-sexual dimorphism of mandibles. J ETHOL 2006. [DOI: 10.1007/s10164-006-0021-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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