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Katsuki M, Uesugi K, Yokoi T, Ozawa T, O'Brien DM, Emlen DJ, Okada K, Okada Y. Morphological and functional analyses for investigation of sexually selected legs in the frog legged beetle Sagra femorata (Coleoptera: Chrysomelidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 80:101360. [PMID: 38704965 DOI: 10.1016/j.asd.2024.101360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/07/2024]
Abstract
Mate choice and male-male combat over successful mating often cause disproportionate exaggeration of male trait relative to body size. However, the exaggeration is often not the only trait involved with male-male combat and mate choice: suites of co-expressed traits may function together as a coordinated unit. When this occurs, dimorphism may be expected for these additional, non-exaggerated, structures. S. femorata males have disproportionately large hind-legs used in male-male combat over females. During the fights, fore- and mid-legs are used to keep males in positions where advantageous for leverage. Because use of the exaggerated hind-legs is coordinated with the other legs, they will coevolve as a functional unit. Here, we show that 1) S. femorata has sexual size differences in all three legs; 2) males show positive allometry in the relative sizes of all three legs; and 3) microstructures of tarsi on the fore- and mid-legs are also sexually dimorphic. Despite these differences in the tarsal microstructure, 4) adhesion forces of the tarsi had no sexual difference in flat surface. The microstructure would be specialized on attaching elytra surface. These results suggest that the three pairs of legs function together during fighting behavior, with hind-legs employed primarily for fighting, and the fore- and mid-legs functioning to grip females, keeping males positioned on the back of the female during combat.
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Affiliation(s)
- Masako Katsuki
- Department of Agricultural and Environmental Biology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan; Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
| | - Kaoru Uesugi
- Department of Mechanical Systems Engineering, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa-cho, Hitachi, Ibaraki 316-8511, Japan
| | - Tomoyuki Yokoi
- Graduate School of Science and Technology, University of Tsukuba, Japan
| | - Takane Ozawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
| | - Devin M O'Brien
- Department of Natural Sciences, SUNY Cobleskill, Cobleskill, NY, 12043, USA
| | - Douglas J Emlen
- Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, Japan
| | - Kensuke Okada
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Tsushima-naka 111, Okayama 700-8530, Japan
| | - Yasukazu Okada
- Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
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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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Morita S, Sakura K, Gotoh H, Emlen DJ, Niimi T. Recent advances in understanding horn formation in the Japanese rhinoceros beetle Trypoxylus dichotomus using next-generation sequencing technology. CURRENT OPINION IN INSECT SCIENCE 2022; 51:100901. [PMID: 35301164 DOI: 10.1016/j.cois.2022.100901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 02/20/2022] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
The exaggerated horns of beetles are attractive models for studying the origin of novel traits and morphological evolution. Closely related species often differ profoundly in the size, number, and shape of their horns, and in the body region from which they extend. In addition, beetle horns exhibit exquisite nutrition-dependent phenotypic plasticity, leading to disproportionate growth of the horns in the largest, best-condition individuals and much smaller - even stunted - horn sizes in poor-condition individuals. These exciting phenomena in beetle horns have recently been revealed at the molecular level with the advent of next-generation sequencing. This section reviews the latest research on a horned beetle, the Japanese rhinoceros beetle Trypoxylus dichotomus, whose genome was recently sequenced.
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Affiliation(s)
- Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Kazuki Sakura
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan
| | - Hiroki Gotoh
- Department of Biological Science, Faculty of Sciences, Shizuoka University, Shizuoka 422-8529, Japan
| | - Douglas J Emlen
- Division of Biological Sciences, 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; Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, 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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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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7
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Yang H, You CJ, Tsui CKM, Tembrock LR, Wu ZQ, Yang DP. Phylogeny and biogeography of the Japanese rhinoceros beetle, Trypoxylus dichotomus (Coleoptera: Scarabaeidae) based on SNP markers. Ecol Evol 2021; 11:153-173. [PMID: 33437420 PMCID: PMC7790660 DOI: 10.1002/ece3.6982] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/23/2020] [Accepted: 10/16/2020] [Indexed: 12/05/2022] Open
Abstract
The Japanese rhinoceros beetle Trypoxylus dichotomus is one of the largest beetle species in the world and is commonly used in traditional Chinese medicine. Ten subspecies of T. dichotomus and a related Trypoxylus species (T. kanamorii) have been described throughout Asia, but their taxonomic delimitations remain problematic. To clarify issues such as taxonomy, and the degree of genetic differentiation of Trypoxylus populations, we investigated the genetic structure, genetic variability, and phylogeography of 53 specimens of Trypoxylus species from 44 locations in five Asian countries (China, Japan, Korea, Thailand, and Myanmar). Using specific-locus amplified fragment sequencing (SLAF-seq) techniques, we developed 330,799 SLAFs over 114.16M reads, in turn yielding 46,939 high-resolution single nucleotide polymorphisms (SNPs) for genotyping. Phylogenetic analysis of SNPs indicated the presence of three distinct genetic groups, suggesting that the various subspecies could be treated as three groups of populations. PCA and ADMIXTURE analysis also identified three genetic clusters (North, South, West), which corresponded to their locations, suggesting that geographic factors were important in maintaining within population homogeneity and between population divergence. Analyses of SNP data confirmed the monophyly of certain subspecies on islands, while other subspecies (e.g., T. d. septentrionalis) were found to be polyphyletic and nested in more than one lineage. AMOVA demonstrated high level of differentiation among populations/groups. Also, pairwise F ST values revealed high differentiation, particularly between South and West, as well as between North and South. Despite the differentiation, measurable gene flow was inferred between genetic clusters but at varying rates and directions. Our study demonstrated that SLAF-seq derived markers outperformed 16S and COII sequences and provided improved resolution of the genetic differentiation of rhinoceros beetle populations from a large part of the species' range.
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Affiliation(s)
- Huan Yang
- School of Pharmaceutical SciencesSun Yat‐Sen UniversityGuangzhouChina
| | - Chong Juan You
- Beijing Key Laboratory for Forest Pest ControlBeijing Forestry UniversityBeijingChina
| | - Clement K. M. Tsui
- Department of PathologySidra MedicineDohaQatar
- Department of Pathology and Laboratory MedicineWeill Cornell Medicine‐QatarAr‐RayyanQatar
- Division of Infectious DiseasesFaculty of MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Luke R. Tembrock
- Department of Agricultural BiologyColorado State UniversityFort CollinsCOUSA
| | - Zhi Qiang Wu
- Shenzhen BranchGuangdong Laboratory for Lingnan Modern AgricultureGenome Analysis Laboratory of the Ministry of AgricultureAgricultural Genomics Institute at ShenzhenChinese Academy of Agricultural SciencesShenzhenChina
| | - De Po Yang
- School of Pharmaceutical SciencesSun Yat‐Sen UniversityGuangzhouChina
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8
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Narayan VP. Digest: Sexually selected weapons: Winning the fight, but losing the war for reproduction on a changing battlefield. Evolution 2020; 75:559-560. [PMID: 33325035 DOI: 10.1111/evo.14145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 12/07/2020] [Indexed: 11/26/2022]
Abstract
What conditions favor the evolution of large animal weapons? In the Japanese rhinoceros beetle, Trypoxylus dichotomus, del Sol et al. found that selection favors large horns in populations where males compete over guardianship of scarce female feeding territories. However, in other populations, an abundance of female feeding territories reduces the chance of mating success for these guarding males, leading to the evolution of relatively shorter horn sizes. This finding illustrates that female habitat and resource use have the potential to influence evolution of male weapon size through sexual selection.
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Affiliation(s)
- Vikram P Narayan
- The School of Biological Sciences, The University of Queensland, Saint Lucia, Queensland, Australia.,College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom
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9
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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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10
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Kojima W, Nakakura T, Fukuda A, Lin C, Harada M, Hashimoto Y, Kawachi A, Suhama S, Yamamoto R. Latitudinal cline of larval growth rate and its proximate mechanisms in a rhinoceros beetle. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13572] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Wataru Kojima
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Tatsunori Nakakura
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Ayumi Fukuda
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Chung‐Ping Lin
- Department of Life Science National Taiwan Normal University Taipei Taiwan
| | - Masahiro Harada
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Yuki Hashimoto
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Aika Kawachi
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Shiho Suhama
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
| | - Ryo Yamamoto
- Graduate School of Sciences and Technology for Innovation Yamaguchi University Yamaguchi Japan
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11
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Wiens JJ, Tuschhoff E. Songs versus colours versus horns: what explains the diversity of sexually selected traits? Biol Rev Camb Philos Soc 2020; 95:847-864. [PMID: 32092241 DOI: 10.1111/brv.12593] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 01/25/2020] [Accepted: 02/10/2020] [Indexed: 01/14/2023]
Abstract
Papers on sexual selection often highlight the incredible diversity of sexually selected traits across animals. Yet, few studies have tried to explain why this diversity evolved. Animals use many different types of traits to attract mates and outcompete rivals, including colours, songs, and horns, but it remains unclear why, for example, some taxa have songs, others have colours, and others horns. Here, we first conduct a systematic survey of the basic diversity and distribution of different types of sexually selected signals and weapons across the animal Tree of Life. Based on this survey, we describe seven major patterns in trait diversity and distributions. We then discuss 10 unanswered questions raised by these patterns, and how they might be addressed. One major pattern is that most types of sexually selected signals and weapons are apparently absent from most animal phyla (88%), in contrast to the conventional wisdom that a diversity of sexually selected traits is present across animals. Furthermore, most trait diversity is clustered in Arthropoda and Chordata, but only within certain clades. Within these clades, many different types of traits have evolved, and many types appear to have evolved repeatedly. By contrast, other major arthropod and chordate clades appear to lack all or most trait types, and similar patterns are repeated at smaller phylogenetic scales (e.g. within insects). Although most research on sexual selection focuses on female choice, we find similar numbers of traits (among sampled species) are involved in male contests (44%) and female choice (55%). Overall, these patterns are largely unexplained and unexplored, as are many other fundamental questions about the evolution of these traits. We suggest that understanding the diversity of sexually selected traits may require a shift towards macroevolutionary studies at relatively deep timescales (e.g. tens to hundreds of millions of years ago).
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Affiliation(s)
- John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - E Tuschhoff
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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12
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Allometry and Fighting Behaviour of a Dimorphic Stag Beetle Cyclommatus mniszechi (Coleoptera: Lucanidae). INSECTS 2020; 11:insects11020081. [PMID: 31979391 PMCID: PMC7074643 DOI: 10.3390/insects11020081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/16/2020] [Accepted: 01/20/2020] [Indexed: 11/30/2022]
Abstract
Male stag beetles (Coleoptera: Lucanidae) use their mandibles as weapons to compete for resources and reproduction. Mandible size in stag beetles can be associated with different behaviours and the outcome of male contests. We investigated the allometric relationship between mandible and body size in males of the stag beetle Cyclommatus mniszechi to uncover distinct morphs. The results divided male C. mniszechi into majors and minors with the switch point of mandible length at 14.01 mm. The allometric slope of mandibles was positive for both morphs but was steeper for the minors. We also characterised the fighting behaviour of the different morphs in size-matched contests using sequential analyses. Males matched each other’s behaviour in contests with many physical contacts, no injury and a progression from low towards high aggression and rare de-escalation. Major and minor males employed the same behavioural elements in contests, but major males were more likely to escalate directly into more aggressive phases and minor males tended to stay within phases. This finding suggests that major males may compete more aggressively than minor males in contests.
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13
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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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14
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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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15
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O'Brien DM, Boisseau RP, Duell M, McCullough E, Powell EC, Somjee U, Solie S, Hickey AJ, Holwell GI, Painting CJ, Emlen DJ. Muscle mass drives cost in sexually selected arthropod weapons. Proc Biol Sci 2019; 286:20191063. [PMID: 31238851 DOI: 10.1098/rspb.2019.1063] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Sexually selected weapons often function as honest signals of fighting ability. If poor-quality individuals produce high-quality weapons, then receivers should focus on other, more reliable signals. Cost is one way to maintain signal integrity. The costs of weapons tend to increase with relative weapon size, and thereby restrict large weapons to high-quality individuals who can produce and maintain them. Weapon cost, however, appears to be unpredictably variable both within and across taxa, and the mechanisms underlying this variation remain unclear. We suggest variation in weapon cost may result from variation in weapon composition-specifically, differences in the amount of muscle mass directly associated with the weapon. We test this idea by measuring the metabolic cost of sexually selected weapons in seven arthropod species and relating these measures to weapon muscle mass. We show that individuals with relatively large weapon muscles have disproportionately high resting metabolic rates and provide evidence that this trend is driven by weapon muscle mass. Overall, our results suggest that variation in weapon cost can be partially explained by variation in weapon morphology and that the integrity of weapon signals may be maintained by increased metabolic cost in species with relatively high weapon muscle mass.
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Affiliation(s)
- Devin M O'Brien
- 1 Department of Biological Sciences, Colby College , Waterville, ME , USA.,2 Division of Biological Sciences, University of Montana , Missoula, MT , USA
| | - Romain P Boisseau
- 2 Division of Biological Sciences, University of Montana , Missoula, MT , USA
| | - Meghan Duell
- 3 School of Life Sciences, Arizona State University , Tempe, AZ , USA
| | - Erin McCullough
- 4 Department of Biology, Syracuse University , Syracuse, NY , USA
| | - Erin C Powell
- 5 School of Biological Sciences, University of Auckland , Auckland , New Zealand
| | - Ummat Somjee
- 6 Entomology and Nematology Department, University of Florida , Gainesville, FL , USA.,7 Smithsonian Tropical Research Institute , Balboa , Ancón , Panamá
| | - Sarah Solie
- 2 Division of Biological Sciences, University of Montana , Missoula, MT , USA.,8 Biology Department, Duke University , Durham, NC , USA
| | - Anthony J Hickey
- 5 School of Biological Sciences, University of Auckland , Auckland , New Zealand
| | - Gregory I Holwell
- 5 School of Biological Sciences, University of Auckland , Auckland , New Zealand
| | - Christina J Painting
- 5 School of Biological Sciences, University of Auckland , Auckland , New Zealand
| | - Douglas J Emlen
- 2 Division of Biological Sciences, University of Montana , Missoula, MT , USA
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16
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Katsube M, Yamada S, Yamaguchi Y, Takakuwa T, Yamamoto A, Imai H, Saito A, Shimizu A, Suzuki S. Critical Growth Processes for the Midfacial Morphogenesis in the Early Prenatal Period. Cleft Palate Craniofac J 2019; 56:1026-1037. [PMID: 30773047 DOI: 10.1177/1055665619827189] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Congenital midfacial hypoplasia often requires intensive treatments and is a typical condition for the Binder phenotype and syndromic craniosynostosis. The growth trait of the midfacial skeleton during the early fetal period has been assumed to be critical for such an anomaly. However, previous embryological studies using 2-dimensional analyses and specimens during the late fetal period have not been sufficient to reveal it. OBJECTIVE To understand the morphogenesis of the midfacial skeleton in the early fetal period via 3-dimensional quantification of the growth trait and investigation of the developmental association between the growth centers and midface. METHODS Magnetic resonance images were obtained from 60 human fetuses during the early fetal period. Three-dimensional shape changes in the craniofacial skeleton along growth were quantified and visualized using geometric morphometrics. Subsequently, the degree of development was computed. Furthermore, the developmental association between the growth centers and the midfacial skeleton was statistically investigated and visualized. RESULTS The zygoma expanded drastically in the anterolateral dimension, and the lateral part of the maxilla developed forward until approximately 13 weeks of gestation. The growth centers such as the nasal septum and anterior portion of the sphenoid were highly associated with the forward growth of the midfacial skeleton (RV = 0.589; P < .001). CONCLUSIONS The development of the midface, especially of the zygoma, before 13 weeks of gestation played an essential role in the midfacial development. Moreover, the growth centers had a strong association with midfacial forward growth before birth.
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Affiliation(s)
- Motoki Katsube
- 1 Department of Plastic and Reconstructive Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.,2 Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shigehito Yamada
- 2 Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,3 Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yutaka Yamaguchi
- 2 Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tetsuya Takakuwa
- 3 Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akira Yamamoto
- 4 Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Hirohiko Imai
- 5 Department of Systems Science, Kyoto University Graduate School of Informatics, Kyoto, Japan
| | - Atsushi Saito
- 6 Institute of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Akinobu Shimizu
- 6 Institute of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Shigehiko Suzuki
- 1 Department of Plastic and Reconstructive Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
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17
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Rico-Guevara A, Hurme KJ. Intrasexually selected weapons. Biol Rev Camb Philos Soc 2019; 94:60-101. [PMID: 29924496 DOI: 10.1111/brv.12436] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 01/24/2023]
Abstract
We propose a practical concept that distinguishes the particular kind of weaponry that has evolved to be used in combat between individuals of the same species and sex, which we term intrasexually selected weapons (ISWs). We present a treatise of ISWs in nature, aiming to understand their distinction and evolution from other secondary sex traits, including from 'sexually selected weapons', and from sexually dimorphic and monomorphic weaponry. We focus on the subset of secondary sex traits that are the result of same-sex combat, defined here as ISWs, provide not previously reported evolutionary patterns, and offer hypotheses to answer questions such as: why have only some species evolved weapons to fight for the opposite sex or breeding resources? We examined traits that seem to have evolved as ISWs in the entire animal phylogeny, restricting the classification of ISW to traits that are only present or enlarged in adults of one of the sexes, and are used as weapons during intrasexual fights. Because of the absence of behavioural data and, in many cases, lack of sexually discriminated series from juveniles to adults, we exclude the fossil record from this review. We merge morphological, ontogenetic, and behavioural information, and for the first time thoroughly review the tree of life to identify separate evolution of ISWs. We found that ISWs are only found in bilateral animals, appearing independently in nematodes, various groups of arthropods, and vertebrates. Our review sets a reference point to explore other taxa that we identify with potential ISWs for which behavioural or morphological studies are warranted. We establish that most ISWs come in pairs, are located in or near the head, are endo- or exoskeletal modifications, are overdeveloped structures compared with those found in females, are modified feeding structures and/or locomotor appendages, are most common in terrestrial taxa, are frequently used to guard females, territories, or both, and are also used in signalling displays to deter rivals and/or attract females. We also found that most taxa lack ISWs, that females of only a few species possess better-developed weapons than males, that the cases of independent evolution of ISWs are not evenly distributed across the phylogeny, and that animals possessing the most developed ISWs have non-hunting habits (e.g. herbivores) or are faunivores that prey on very small prey relative to their body size (e.g. insectivores). Bringing together perspectives from studies on a variety of taxa, we conceptualize that there are five ways in which a sexually dimorphic trait, apart from the primary sex traits, can be fixed: sexual selection, fecundity selection, parental role division, differential niche occupation between the sexes, and interference competition. We discuss these trends and the factors involved in the evolution of intrasexually selected weaponry in nature.
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Affiliation(s)
- Alejandro Rico-Guevara
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A.,Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Código Postal 11001, Bogotá DC, Colombia
| | - Kristiina J Hurme
- Department of Integrative Biology, University of California, Berkeley, 3040 Valley Life Sciences Building, Berkeley, CA, 94720, U.S.A.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd, Unit 3043, Storrs, CT, 06269, U.S.A
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18
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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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19
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O’Brien DM, Boisseau RP. Overcoming mechanical adversity in extreme hindleg weapons. PLoS One 2018; 13:e0206997. [PMID: 30403752 PMCID: PMC6221328 DOI: 10.1371/journal.pone.0206997] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/23/2018] [Indexed: 01/04/2023] Open
Abstract
The size of sexually selected weapons and their performance in battle are both critical to reproductive success, yet these traits are often in opposition. Bigger weapons make better signals. However, due to the mechanical properties of weapons as lever systems, increases in size may inhibit other metrics of performance as different components of the weapon grow out of proportion with one another. Here, using direct force measurements, we investigated the relationship between weapon size and weapon force production in two hindleg weapon systems, frog-legged beetles (Sagra femorata) and leaf-footed cactus bugs (Narnia femorata), to test for performance tradeoffs associated with increased weapon size. In male frog-legged beetles, relative force production decreased as weapon size increased. Yet, absolute force production was maintained across weapon sizes. Surprisingly, mechanical advantage was constant across weapon sizes and large weaponed males had disproportionately large leg muscles. In male leaf-footed cactus bugs, on the other hand, there was no relationship between weapon size and force production, likely reflecting the importance of their hindlegs as signals rather than force-producing structures of male-male competition. Overall, our results suggest that when weapon force production is important for reproductive success, large weaponed animals may overcome mechanical challenges by maintaining proportional lever components and investing in (potentially costly) compensatory mechanisms.
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Affiliation(s)
- Devin M. O’Brien
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Romain P. Boisseau
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
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20
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On the evolution of extreme structures: static scaling and the function of sexually selected signals. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.08.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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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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22
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O'Brien DM, Katsuki M, Emlen DJ. Selection on an extreme weapon in the frog‐legged leaf beetle (
Sagra femorata
). Evolution 2017; 71:2584-2598. [DOI: 10.1111/evo.13336] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/21/2017] [Accepted: 08/10/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Devin M. O'Brien
- Division of Biological Sciences University of Montana Missoula Montana
| | - Masako Katsuki
- Department of Arts and Sciences University of Tokyo Tokyo Japan
| | - Douglas J. Emlen
- Division of Biological Sciences University of Montana Missoula Montana
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23
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Katsube M, Yamada S, Miyazaki R, Yamaguchi Y, Makishima H, Takakuwa T, Yamamoto A, Fujii Y, Morimoto N, Ito T, Imai H, Suzuki S. Quantitation of nasal development in the early prenatal period using geometric morphometrics and MRI: a new insight into the critical period of Binder phenotype. Prenat Diagn 2017; 37:907-915. [PMID: 28675493 DOI: 10.1002/pd.5106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/02/2017] [Accepted: 06/29/2017] [Indexed: 11/09/2022]
Abstract
OBJECTIVES Disturbance of the development of the nasal septum in the early prenatal period causes congenital facial anomalies characterized by a flat nose and defects of the anterior nasal spine (ANS), such as Binder phenotype. The present research aimed to assess the development of the nasal septum and the ANS with growth in the early prenatal period. METHODS Magnetic resonance images were obtained from 56 specimens. Mid-sagittal images were analyzed by using geometric morphometrics for the development of the nasal septum, and angle analysis was performed for the development of the ANS. Additionally, we calculated and visualized the ontogenetic allometry of the nasal septum. RESULTS Our results showed that the nasal septum changed shape in the anteroposterior direction in smaller specimens, while it maintained an almost isometric shape in larger specimens. Furthermore, mathematical evidence revealed that the maturation periods of the shapes of the ANS and the nasal septum were around 12 and 14 weeks of gestation, respectively. CONCLUSION The anteroposterior development of the nasal septum is specific until 14 weeks of gestation, and it is important for nasal protrusion and the development of the ANS. Therefore, the disturbance of such development could induce low nasal deformity, including Binder phenotype. © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Motoki Katsube
- Department of Plastic and Reconstructive Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shigehito Yamada
- Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Reina Miyazaki
- Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yutaka Yamaguchi
- Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Haruyuki Makishima
- Congenital Anomaly Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tetsuya Takakuwa
- Human Health Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Akira Yamamoto
- Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Yosuke Fujii
- Statistical Genetics, Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Naoki Morimoto
- Department of Zoology, Kyoto University Graduate School of Science, Kyoto, Japan
| | - Tsuyoshi Ito
- Primate Research Institute, Kyoto University, Aichi, Japan.,The Keihanshin Consortium for Fostering the Next Generation of Global Leaders in Research (K-CONNEX), Kyoto, Japan
| | - Hirohiko Imai
- Department of Systems Science, Kyoto University Graduate School of Informatics, Kyoto, Japan
| | - Shigehiko Suzuki
- Department of Plastic and Reconstructive Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
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24
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Lemaître JF, Gaillard JM. Reproductive senescence: new perspectives in the wild. Biol Rev Camb Philos Soc 2017; 92:2182-2199. [PMID: 28374548 DOI: 10.1111/brv.12328] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/23/2017] [Accepted: 03/03/2017] [Indexed: 11/26/2022]
Abstract
According to recent empirical studies, reproductive senescence, the decline in reproductive success with increasing age, seems to be nearly ubiquitous in the wild. However, a clear understanding of the evolutionary causes and consequences of reproductive senescence is still lacking and requires new and integrative approaches. After identifying the sequential and complex nature of female reproductive senescence, we show that the relative contributions of physiological decline and alterations in the efficiency of parental care to reproductive senescence remain unknown and need to be assessed in the light of current evolutionary theories of ageing. We demonstrate that, although reproductive senescence is generally studied only from the female viewpoint, age-specific female reproductive success strongly depends on male-female interactions. Thus, a reduction in male fertilization efficiency with increasing age has detrimental consequences for female fitness. Lastly, we call for investigations of the role of environmental conditions on reproductive senescence, which could provide salient insights into the underlying sex-specific mechanisms of reproductive success. We suggest that embracing such directions should allow building new bridges between reproductive senescence and the study of sperm competition, parental care, mate choice and environmental conditions.
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Affiliation(s)
- Jean-François Lemaître
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
| | - Jean-Michel Gaillard
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
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25
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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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26
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Herberstein ME, Painting CJ, Holwell GI. Scramble Competition Polygyny in Terrestrial Arthropods. ADVANCES IN THE STUDY OF BEHAVIOR 2017. [DOI: 10.1016/bs.asb.2017.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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27
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Cooley NL, Emlen DJ, Woods HA. Self-heating by large insect larvae? J Therm Biol 2016; 62:76-83. [PMID: 27839554 DOI: 10.1016/j.jtherbio.2016.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 10/08/2016] [Accepted: 10/16/2016] [Indexed: 11/28/2022]
Abstract
Do insect larvae ever self-heat significantly from their own metabolic activity and, if so, under what sets of environmental temperatures and across what ranges of body size? We examine these questions using larvae of the Japanese rhinoceros beetle (Trypoxylus dichotomus), chosen for their large size (>20g), simple body plan, and underground lifestyle. Using CO2 respirometry, we measured larval metabolic rates then converted measured rates of gas exchange into rates of heat production and developed a mathematical model to predict how much steady state body temperatures of underground insects would increase above ambient depending on body size. Collectively, our results suggest that large, extant larvae (20-30g body mass) can self-heat by at most 2°C, and under many common conditions (shallow depths, moister soils) would self-heat by less than 1°C. By extending the model to even larger (hypothetical) body sizes, we show that underground insects with masses >1kg could heat, in warm, dry soils, by 1.5-6°C or more. Additional experiments showed that larval critical thermal maxima (CTmax) were in excess of 43.5°C and that larvae could behaviorally thermoregulate on a thermal gradient bar. Together, these results suggest that large larvae living underground likely regulate their temperatures primarily using behavior; self-heating by metabolism likely contributes little to their heat budgets, at least in most common soil conditions.
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Affiliation(s)
- Nikita L Cooley
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA
| | - Douglas J Emlen
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA
| | - H Arthur Woods
- Division of Biological Sciences, 32 Campus Drive HS104, University of Montana, Missoula, MT, 59812, USA.
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Vendl T, Kratochvíl L, Šípek P. Ontogeny of sexual size dimorphism in the hornless rose chafer Pachnoda marginata (Coleoptera: Scarabaeidae: Cetoniinae). ZOOLOGY 2016; 119:481-488. [PMID: 27470929 DOI: 10.1016/j.zool.2016.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 06/07/2016] [Accepted: 07/11/2016] [Indexed: 10/21/2022]
Abstract
Beetles of the subfamily Cetoniinae are distinct and well-known, yet their larval ontogeny, sexual size dimorphism and development remain unknown in most species. This group contains many species with large males with prominent secondary sexual structures, such as cephalic or pronotal horns and elongated forelimbs. The species studied here, Pachnoda marginata, belongs to those species without any obvious dimorphism, the males being almost indistinguishable from the females. In this paper we examine sexual dimorphism in body shape and size in this apparently 'non-dimorphic' species. We further investigate the larval development and proximate causes of sexual size dimorphism, in particular when and how the sexes diverge in their growth trajectories during ontogeny. We found that males are larger than females and that the sexes also differ in body shape - for example, males possess significantly longer forelimbs relative to body size than females. The male-biased sexual size dimorphism along with prolonged forelimbs suggests that sexual selection for larger males may not be limited merely to horned species of rose chafers. The dimorphism in size in P. marginata arises during the second larval instar and basically remains unchanged till maturity. In both sexes the maximum body mass as well as developmental time of particular larval instars were strongly correlated, but time spent in the pupal chamber was not related to previous growth and final body size. The correlation between developmental time and adult size was negative, which may be a reflection of differences in resource allocation or utilisation for growth and development among individuals.
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Affiliation(s)
- Tomáš Vendl
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic.
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic
| | - Petr Šípek
- Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic
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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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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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Kojima W. Attraction to Carbon Dioxide from Feeding Resources and Conspecific Neighbours in Larvae of the Rhinoceros Beetle Trypoxylus dichotomus. PLoS One 2015; 10:e0141733. [PMID: 26536591 PMCID: PMC4633205 DOI: 10.1371/journal.pone.0141733] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/11/2015] [Indexed: 11/30/2022] Open
Abstract
Saprophagous (feeding on decaying matter) insects often use carbon dioxide (CO2) as a cue for finding food. Humus-feeding larvae of the giant rhinoceros beetle Trypoxylus dichotomus exhibit a clumped distribution in natural microhabitats, but the mechanisms driving the distribution were unknown. Herein, I examined whether larvae use CO2 as a cue for fermented humus and aggregate in the vicinity of the food. I found that (i) larvae of T. dichotomus are strongly attracted to CO2, (ii) larvae orient toward highly fermented humus when given a choice between highly and poorly fermented humus, (iii) the highly fermented humus emits more CO2 than the poorly fermented humus, and (iv) larvae grow larger when fed highly fermented humus rather than poorly fermented humus. The clumped distribution of larvae is probably formed along the concentration gradient of CO2 induced by heterogeneity of fermented organic materials in soil. My laboratory experiments also revealed that larvae are chemically attracted to each other. Moreover, CO2 concentrations in soil were increased by the larval respiration, and small amounts of CO2 (much less than emitted during respiration by a single larva) were sufficient for larval attraction. These results suggest that not only response to fermented food resources, but also respiratory CO2 from conspecifics may lead to aggregation. Enhanced densities resulted in reduced weight gain under experimental conditions. However, exploiting a high-value resource at enhanced densities still led to greater body weight compared to individually exploiting a low-value resource. This demonstrates the adaptive value of the response to CO2 sources in this species.
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Affiliation(s)
- Wataru Kojima
- Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
- * E-mail:
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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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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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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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Lavine L, Gotoh H, Brent CS, Dworkin I, Emlen DJ. Exaggerated trait growth in insects. ANNUAL REVIEW OF ENTOMOLOGY 2015; 60:453-472. [PMID: 25341090 DOI: 10.1146/annurev-ento-010814-021045] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Animal structures occasionally attain extreme proportions, eclipsing in size the surrounding body parts. We review insect examples of exaggerated traits, such as the mandibles of stag beetles (Lucanidae), the claspers of praying mantids (Mantidae), the elongated hindlimbs of grasshoppers (Orthoptera: Caelifera), and the giant heads of soldier ants (Formicidae) and termites (Isoptera). Developmentally, disproportionate growth can arise through trait-specific modifications to the activity of at least four pathways: the sex determination pathway, the appendage patterning pathway, the insulin/IGF signaling pathway, and the juvenile hormone/ecdysteroid pathway. Although most exaggerated traits have not been studied mechanistically, it is already apparent that distinct developmental mechanisms underlie the evolution of the different types of exaggerated traits. We suggest this reflects the nature of selection in each instance, revealing an exciting link between mechanism, form, and function. We use this information to make explicit predictions for the types of regulatory pathways likely to underlie each type of exaggerated trait.
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Affiliation(s)
- Laura Lavine
- Department of Entomology, Washington State University, Pullman, Washington 99164; ,
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36
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Kojima W. Mechanism of synchronous metamorphosis: larvae of a rhinoceros beetle alter the timing of pupation depending on maturity of their neighbours. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1854-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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White CR, Kearney MR. Metabolic scaling in animals: methods, empirical results, and theoretical explanations. Compr Physiol 2014; 4:231-56. [PMID: 24692144 DOI: 10.1002/cphy.c110049] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Life on earth spans a size range of around 21 orders of magnitude across species and can span a range of more than 6 orders of magnitude within species of animal. The effect of size on physiology is, therefore, enormous and is typically expressed by how physiological phenomena scale with mass(b). When b ≠ 1 a trait does not vary in direct proportion to mass and is said to scale allometrically. The study of allometric scaling goes back to at least the time of Galileo Galilei, and published scaling relationships are now available for hundreds of traits. Here, the methods of scaling analysis are reviewed, using examples for a range of traits with an emphasis on those related to metabolism in animals. Where necessary, new relationships have been generated from published data using modern phylogenetically informed techniques. During recent decades one of the most controversial scaling relationships has been that between metabolic rate and body mass and a number of explanations have been proposed for the scaling of this trait. Examples of these mechanistic explanations for metabolic scaling are reviewed, and suggestions made for comparing between them. Finally, the conceptual links between metabolic scaling and ecological patterns are examined, emphasizing the distinction between (1) the hypothesis that size- and temperature-dependent variation among species and individuals in metabolic rate influences ecological processes at levels of organization from individuals to the biosphere and (2) mechanistic explanations for metabolic rate that may explain the size- and temperature-dependence of this trait.
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Affiliation(s)
- Craig R White
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
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38
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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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39
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Painting CJ, Holwell GI. Flexible alternative mating tactics by New Zealand giraffe weevils. Behav Ecol 2014. [DOI: 10.1093/beheco/aru140] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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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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41
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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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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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Álvarez HA, Serrano-Meneses MA, Reyes-Márquez I, Jiménez-Cortés JG, Córdoba-Aguilar A. Allometry of a sexual trait in relation to diet experience and alternative mating tactics in two rubyspot damselflies (Calopterygidae:Hetaerina). Biol J Linn Soc Lond 2013. [DOI: 10.1111/j.1095-8312.2012.02031.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hugo A. Álvarez
- Laboratorio de Ecología de Poblaciones; Escuela de Biología; Benemérita Universidad Autónoma de Puebla; Blvd. Valsequillo y Av. San Claudio, Edificio 112-A, Col. Jardines de San Manuel, Ciudad Universitaria CP 72570 Puebla México
| | - Martín Alejandro Serrano-Meneses
- Laboratorio de Biología Evolutiva; Centro Tlaxcala de Biología de la Conducta; Universidad Autónoma de Tlaxcala; Carretera Tlaxcala-Puebla Km. 1.5 90062 Tlaxcala México
| | - Isidora Reyes-Márquez
- Laboratorio de Biología Evolutiva; Centro Tlaxcala de Biología de la Conducta; Universidad Autónoma de Tlaxcala; Carretera Tlaxcala-Puebla Km. 1.5 90062 Tlaxcala México
| | - Jesús Guillermo Jiménez-Cortés
- Departamento de Ecología Evolutiva; Instituto de Ecología; Universidad Nacional Autónoma de México; Apdo. Postal 70-275, Ciudad Universitaria 04510 México DF México
| | - Alex Córdoba-Aguilar
- Departamento de Ecología Evolutiva; Instituto de Ecología; Universidad Nacional Autónoma de México; Apdo. Postal 70-275, Ciudad Universitaria 04510 México DF México
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Emlen DJ, Warren IA, Johns A, Dworkin I, Lavine LC. A mechanism of extreme growth and reliable signaling in sexually selected ornaments and weapons. Science 2012; 337:860-4. [PMID: 22837386 DOI: 10.1126/science.1224286] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many male animals wield ornaments or weapons of exaggerated proportions. We propose that increased cellular sensitivity to signaling through the insulin/insulin-like growth factor (IGF) pathway may be responsible for the extreme growth of these structures. We document how rhinoceros beetle horns, a sexually selected weapon, are more sensitive to nutrition and more responsive to perturbation of the insulin/IGF pathway than other body structures. We then illustrate how enhanced sensitivity to insulin/IGF signaling in a growing ornament or weapon would cause heightened condition sensitivity and increased variability in expression among individuals--critical properties of reliable signals of male quality. The possibility that reliable signaling arises as a by-product of the growth mechanism may explain why trait exaggeration has evolved so many different times in the context of sexual selection.
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Affiliation(s)
- Douglas J Emlen
- Division of Biological Sciences, The University of Montana, 104 Health Science Building, Missoula, MT 59812, USA.
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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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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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Ketmaier V, Stuckas H, Hempel J, Landeck I, Tobler M, Plath M, Tiedemann R. Genetic and morphological divergence among Gravel Bank Grasshoppers, Chorthippus pullus (Acrididae), from contrasting environments. ORG DIVERS EVOL 2010. [DOI: 10.1007/s13127-010-0031-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Hongo Y, Kaneda H. Field Observations of Predation by the Ural Owl Strix uralensis upon the Japanese Horned Beetle Trypoxylus dichotomus septentrionalis. ACTA ACUST UNITED AC 2009. [DOI: 10.3312/jyio.40.90] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Affiliation(s)
- Douglas J. Emlen
- Division of Biological Sciences, The University of Montana, Missoula, Montana 59812;
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