DOCSLIB.ORG

Biomechanical Determinants of Bite Force Dimorphism in Cyclommatus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Biomechanical Determinants of Bite Force Dimorphism in Cyclommatus © 2014. Published by The Company of Biologists Ltd | The Journal of Experimental Biology (2014) 217, 1065-1071 doi:10.1242/jeb.091744 RESEARCH ARTICLE Biomechanical determinants of bite force dimorphism in Cyclommatus metallifer stag beetles Jana Goyens1,2,*, Joris Dirckx2, Manuel Dierick3, Luc Van Hoorebeke3 and Peter Aerts1,4 ABSTRACT 2008; Inoue and Hasegawa, 2013; Kawano, 2006; Shiokawa and In the stag beetle family (Lucanidae), males have diverged from Iwahashi, 2000; Tatsuta et al., 2001). During such fights, opponents females by sexual selection. The males fight each other for mating try to grip each other and the winner will lift the other male and opportunities with their enlarged mandibles. It is known that owners throw it backwards (Shiokawa and Iwahashi, 2000) (authors’ of larger fighting apparatuses are favoured to win the male–male personal observations; see supplementary material Movie 1). Male fights, but it was unclear whether male stag beetles also need to stag beetles with larger mandibles have been shown to win these produce high bite forces while grabbing and lifting opponents in male–male fights more often (Emlen et al., 2005; Hosoya and fights. We show that male Cyclommatus metallifer stag beetles bite Araya, 2005; Tatsuta et al., 2001). three times as forcefully as females. This is not entirely unexpected Most research on bite performance and sexual dimorphism has given the spectacular nature of the fights, but all the more impressive been performed on lizards. As in stag beetles, male lizards often given the difficulty of achieving this with their long mandibles (long have larger body and head sizes (Herrel et al., 1995; Herrel et al., levers). Our results suggest no increase in male intrinsic muscle 2007), the latter being correlated with higher male bite forces strength to accomplish this. However, morphological analyses show (Herrel et al., 1999; Herrel et al., 2001; Herrel et al., 2007; that the long mandibular output levers in males are compensated by Verwaijen et al., 2002). It has been suggested that this sexual elongated input levers (and thus a wider anterior side of the head). dimorphism arose by sexual selection on male bite force and natural The surplus of male bite force capability is realized by enlargement selection on diet [prey size and toughness (Herrel et al., 1995; Herrel of the closer muscles of the mandibles, while overall muscle force et al., 1999; Vanhooydonck et al., 2010)]. The large male stag beetle direction remained optimal. To enable the forceful bites required to head may suggest a similar system, leading to higher bite force in ensure male reproductive success, male head size and shape are males compared with females. However, it remains unexplored adapted for long input levers and large muscles. Therefore, the entire whether bite force, as such, determines fight outcome [such as head should be regarded as an integral part of male armature. already observed, for instance, in several lizard species, field crickets and fanged frogs (e.g. Emerson and Voris, 1992; Hall et al., KEY WORDS: Lucanidae, Sexual dimorphism, Bite force, 2010; Husak et al., 2006; Huyghe et al., 2005; Lailvaux et al., Functional morphology 2004)]. Indeed, fighting success in male stag beetles may rely equally well on firm interlocking between the ornamented jaws and INTRODUCTION the exoskeleton of the opponent without the need for a forceful Insect mandibles are often adapted into tools for various tasks: e.g. pinch [comparable to the interlocking of antlers in fighting red deer fighting, digging, leaf-cutting, grooming and transporting liquids in stags (Clutton-Brock et al., 1979; Lincoln, 1972)]. If, however, ants; penetrating the soft tissues of snails and attaching to amphibian forceful biting should prove to be important in stag beetle contests, skin in ground beetles; cutting mature tree leaves and tearing and male stag beetles face an additional problem: strongly elongated shredding young tree leaves in saturniids (Bernays, 1998; Bernays mandibles mean long output levers that reduce the force and Janzen, 1988; Ober et al., 2011; Paul, 2001; Wizen and Gasith, transmission from the closer muscles to the mandibular bite points. 2011). Male stag beetles (Lucanidae) are widely known for their In this case, other compensatory adaptations for the enlarged output extraordinary mandibles: a conspicuous sexual dimorphism where lever should be present in male stag beetles. males can have mandibles in a variety of shapes that can be almost In this paper, we investigate the sexual dimorphism of the as long as their own body, while female mandibles are small and mandibular apparatus and the bite force in Cyclommatus metallifer indistinct (Kawano, 2006). The small female mandibles are used to Boisduval 1835 stag beetles. This Indonesian species belongs to the dig in rotten wood (for oviposition) and in soil (when emerging from genus Cyclommatus, which includes (together with the genus their cocoon and to hide from predators), and possibly to pierce tree Prosopocoilus) stag beetle species with the most oversized male bark to feed from sap runs (Percy, 1998; Tanahashi et al., 2009; mandibles (Gotoh et al., 2012; Kawano, 2006). In order to assess the Tanahashi et al., 2010). Male stag beetles, however, fight each other effects of male sexual dimorphism on function and performance, one with their enlarged mandibles to gain access to females (Emlen, should, ideally, compare with non-dimorphic conspecific males. In (stag) beetles, comparison with properly scaled females (see Materials 1University of Antwerp, Laboratory of Functional Morphology, Universiteitsplein 1, and methods) can be used as a proxy for such a hypothetical non- B-2610 Antwerp, Belgium. 2University of Antwerp, Laboratory of BioMedical dimorphic male, as for species without sexual dimorphism (except for 3 Physics, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Ghent University, the reproductive organs), males and females can hardly (if at all) be UGCT-Department of Physics and Astronomy, Faculty of Sciences, Proeftuinstraat 86, 9000 Ghent, Belgium. 4Ghent University, Department of Movement and Sport discerned from each other (Hosoya and Araya, 2005; Kawano, 2006). Sciences, Watersportlaan 2, 9000 Ghent, Belgium. We hypothesize that males show an increased bite force performance compared with females. Okada and Hasegawa (Okada *Author for correspondence ([email protected]) and Hasegawa, 2005) suggested that the stag beetle mating system Received 5 June 2013; Accepted 5 December 2013 is not based on female choice. Therefore, it seems likely that the The Journal of Experimental Biology 1065 RESEARCH ARTICLE The Journal of Experimental Biology (2014) doi:10.1242/jeb.091744 Morphology and morphometrics List of symbols and abbreviations Micro-CT reconstructions give us an insight into the interior of the Fbite,measured measured bite force, tangent to the orbit of the bite point head (see Fig. 3). The general anatomy of the head is similar to that Fbite,predicted calculated bite force of other beetles (Gorb and Beutel, 2000; Li et al., 2011). The F calculated muscle force muscle mandibles articulate by a hinge axis, formed by a pair of condyles. Fp measured bite force, perpendicular to the bite plates Fp force perpendicular to the bite plates The closer muscle is cone shaped and is distinctly larger than the MI muscle insertion point on mandible opener muscle: it almost completely fills the head capsule. MMA posterior body part, mesothorax + metathorax + abdomen Table 1 provides the input and output lever lengths as well as the PCSA physiological cross-sectional area lever ratios. In absolute terms, as well as expressed relative to the ri input lever vector width of the posterior part of the body [mesothorax + metathorax + ro output lever vector r input lever length abdomen (MMA); see Fig. 5], the males have longer levers than the i females. The lever ratio is not significantly different between males ro output lever length α mandibular angle and females, as shown by the nonparametric Wilcoxon rank sum test β 3D angle between Fbite,measured and ro (P=0.051). Given the low P-value and the low statistical power of γ 3D angle between Fmuscle and ri the test, this indicates that the long input levers compensate for the long male output levers, albeit probably not completely. mandibular system is optimized for fight performance. As mentioned, this should be accompanied by further adaptations of the Muscle geometry mandibular system, e.g. as observed for the cheliceral system in Male as well as female mandible closer muscles almost fill the entire camel spiders (van der Meijden et al., 2012). In this regard, the head (see Morphology and morphometrics, above). However, specific working hypotheses that we tested are: (1) males have because head shape and relative size differ, the normalized prolonged input levers to compensate for their long output levers, physiological cross-sectional area (PCSA) of the male closer muscle (2) male mandibular muscles are geometrically advantageous is almost 2.5 times larger (see Table 1). compared with those of females (in terms of size and working The force components of the closer muscle in the x-, y- and z- direction), and (3) these muscles are intrinsically stronger than directions are given in Table 2, averaged over the range of in vivo female muscles. used mandible positions (see Fig. 4). The absolute value of the y- component lies very close to 1 for both males and females, RESULTS indicating that the muscle
Load more

Recommended publications
  • The Early Evolution of Biting–Chewing Performance in Hexapoda
    Chapter 6 The Early Evolution of Biting–Chewing Performance in Hexapoda Alexander Blanke Abstract Insects show a plethora of different mandible shapes. It was advocated that these mandible shapes are mainly a function of different feeding habits. This hypothesis was tested on a larger sampling of non-holometabolan biting–chewing insects with additional tests to understand the interplay of mandible function, feeding guild, and phylogeny. The results show that at the studied systematic level, variation in mandible biting–chewing effectivity is regulated to a large extent by phylogenetic history and the configuration of the mandible joints rather than the food preference of a given taxon. Additionally, lineages with multiple mandibular joints such as primary wingless hexapods show a wider functional space occupation of mandibular effectivity than dicondylic insects (¼ silverfish + winged insects) at significantly different evolutionary rates. The evolution and occupation of a compa- rably narrow functional performance space of dicondylic insects is surprising given the low effectivity values of this food uptake solution. Possible reasons for this relative evolutionary “stasis” are discussed. 6.1 Introduction Insecta sensu lato (¼ Hexapoda) display a high diversity of mouthpart shapes within the early evolved lineages which started to radiate approximately 479 million years ago (Misof et al. 2014). These shape changes were described qualitatively and were often stated to relate mainly to the type of food consumed (Yuasa 1920; Isely 1944; Evans and Forsythe 1985; Chapman and de Boer 1995). To the knowledge of the author, this and related statements regarding mouthpart mechanics being shaped by functional demands have never been tested in a quantitative framework.
    [Show full text]
  • Phylogeography and DNA-Based Species
    RESEARCH ARTICLE Phylogeography and DNA-based species delimitation provide insight into the taxonomy of the polymorphic rose chafer Protaetia (Potosia) cuprea species complex (Coleoptera: Scarabaeidae: Cetoniinae) in the Western Palearctic a1111111111 Dominik VondraÂček1☯*, Aneta Fuchsova 1³, Dirk Ahrens2³, David KraÂl1³, Petr SÏ Âõpek1☯ a1111111111 a1111111111 1 Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic, 2 Department of Arthropoda, Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany a1111111111 a1111111111 ☯ These authors contributed equally to this work. ³ These authors also contributed equally to this work. * [email protected] OPEN ACCESS Abstract Citation: VondraÂček D, Fuchsova A, Ahrens D, KraÂl D, SÏÂõpek P (2018) Phylogeography and DNA-based The development of modern methods of species delimitation, unified under the ªintegrated species delimitation provide insight into the taxonomyº approach, allows a critical examination and re-evaluation of complex taxonomic taxonomy of the polymorphic rose chafer Protaetia groups. The rose chafer Protaetia (Potosia) cuprea is a highly polymorphic species group (Potosia) cuprea species complex (Coleoptera: Scarabaeidae: Cetoniinae) in the Western with a large distribution range. Despite its overall commonness, its taxonomy is unclear and Palearctic. PLoS ONE 13(2): e0192349. https://doi. subject to conflicting hypotheses, most of which largely fail to account for its evolutionary org/10.1371/journal.pone.0192349 history. Based on the sequences of two mitochondrial markers from 65 individuals collected Editor: Bi-Song Yue, Sichuan University, CHINA across the species range, and a detailed analysis of morphological characters including a Received: November 6, 2017 geometric morphometry approach, we infer the evolutionary history and phylogeography of the P. cuprea species complex.
    [Show full text]
  • 1 Evolution of Sexual Development and Sexual Dimorphism in Insects 1
    1 Evolution of sexual development and sexual dimorphism in insects 2 3 Ben R. Hopkins1* & Artyom Kopp1 4 5 1. Department of Evolution and Ecology, University of California – Davis, Davis, USA 6 7 * Corresponding author 8 9 Corresponding author email: [email protected] 10 11 12 13 14 Abstract 15 Most animal species consist of two distinct sexes. At the morphological, physiological, and 16 behavioural levels the differences between males and females are numerous and dramatic, yet 17 at the genomic level they are often slight or absent. This disconnect is overcome because simple 18 genetic differences or environmental signals are able to direct the sex-specific expression of a 19 shared genome. A canonical picture of how this process works in insects emerged from decades 20 of work on Drosophila. But recent years have seen an explosion of molecular-genetic and 21 developmental work on a broad range of insects. Drawing these studies together, we describe 22 the evolution of sexual dimorphism from a comparative perspective and argue that insect sex 23 determination and differentiation systems are composites of rapidly evolving and highly 24 conserved elements. 25 1 26 Introduction 27 Anisogamy is the definitive sex difference. The bimodality in gamete size it describes 28 represents the starting point of a cascade of evolutionary pressures that have generated 29 remarkable divergence in the morphology, physiology, and behaviour of the sexes [1]. But 30 sexual dimorphism presents a paradox: how can a genome largely shared between the sexes 31 give rise to such different forms? A powerful resolution is via sex-specific expression of shared 32 genes.
    [Show full text]
  • The Evolution of Animal Weapons
    The Evolution of Animal Weapons Douglas J. Emlen Division of Biological Sciences, The University of Montana, Missoula, Montana 59812; email: [email protected] Annu. Rev. Ecol. Evol. Syst. 2008. 39:387-413 Key Words First published online as a Review in Advance on animal diversity, sexual selection, male competition, horns, antlers, tusks September 2, 2008 The Annual Review of Ecology, Evolution, and Abstract Systematics is online at ecolsys.annualreviews.org Males in many species invest substantially in structures that are used in com- This article's doi: bat with rivals over access to females. These weapons can attain extreme 10.1146/annurev.ecolsys.39.110707.173 502 proportions and have diversified in form repeatedly. I review empirical lit- Copyright © 2008 by Annual Reviews. erature on the function and evolution of sexually selected weapons to clarify All rights reserved important unanswered questions for future research. Despite their many 1543-592X/08/1201-0387$20.00 shapes and sizes, and the multitude of habitats within which they function, animal weapons share many properties: They evolve when males are able to defend spatially restricted critical resources, they are typically the most variable morphological structures of these species, and this variation hon- estly reflects among-individual differences in body size or quality. What is not clear is how, or why, these weapons diverge in form. The potential for male competition to drive rapid divergence in weapon morphology remains one of the most exciting and understudied topics in sexual selection research today. 3*7 INTRODUCTION Sexual selection is credited with the evolution of nature's most extravagant structures, and these include showy male adornments that are attractive to females (ornaments) and an arsenal of outgrowths that function in male-male combat (weapons) (Darwin 1871).
    [Show full text]
  • WORLD LIST of EDIBLE INSECTS 2015 (Yde Jongema) WAGENINGEN UNIVERSITY PAGE 1
    WORLD LIST OF EDIBLE INSECTS 2015 (Yde Jongema) WAGENINGEN UNIVERSITY PAGE 1 Genus Species Family Order Common names Faunar Distribution & References Remarks life Epeira syn nigra Vinson Nephilidae Araneae Afregion Madagascar (Decary, 1937) Nephilia inaurata stages (Walck.) Nephila inaurata (Walckenaer) Nephilidae Araneae Afr Madagascar (Decary, 1937) Epeira nigra Vinson syn Nephila madagscariensis Vinson Nephilidae Araneae Afr Madagascar (Decary, 1937) Araneae gen. Araneae Afr South Africa Gambia (Bodenheimer 1951) Bostrichidae gen. Bostrichidae Col Afr Congo (DeFoliart 2002) larva Chrysobothris fatalis Harold Buprestidae Col jewel beetle Afr Angola (DeFoliart 2002) larva Lampetis wellmani (Kerremans) Buprestidae Col jewel beetle Afr Angola (DeFoliart 2002) syn Psiloptera larva wellmani Lampetis sp. Buprestidae Col jewel beetle Afr Togo (Tchibozo 2015) as Psiloptera in Tchibozo but this is Neotropical Psiloptera syn wellmani Kerremans Buprestidae Col jewel beetle Afr Angola (DeFoliart 2002) Psiloptera is larva Neotropicalsee Lampetis wellmani (Kerremans) Steraspis amplipennis (Fahr.) Buprestidae Col jewel beetle Afr Angola (DeFoliart 2002) larva Sternocera castanea (Olivier) Buprestidae Col jewel beetle Afr Benin (Riggi et al 2013) Burkina Faso (Tchinbozo 2015) Sternocera feldspathica White Buprestidae Col jewel beetle Afr Angola (DeFoliart 2002) adult Sternocera funebris Boheman syn Buprestidae Col jewel beetle Afr Zimbabwe (Chavanduka, 1976; Gelfand, 1971) see S. orissa adult Sternocera interrupta (Olivier) Buprestidae Col jewel beetle Afr Benin (Riggi et al 2013) Cameroun (Seignobos et al., 1996) Burkina Faso (Tchimbozo 2015) Sternocera orissa Buquet Buprestidae Col jewel beetle Afr Botswana (Nonaka, 1996), South Africa (Bodenheimer, 1951; syn S. funebris adult Quin, 1959), Zimbabwe (Chavanduka, 1976; Gelfand, 1971; Dube et al 2013) Scarites sp. Carabidae Col ground beetle Afr Angola (Bergier, 1941), Madagascar (Decary, 1937) larva Acanthophorus confinis Laporte de Cast.
    [Show full text]
  • A. Kumbang Dewasa
    Keanekaragaman KUMBANG STAG (Coleoptera: Lucanidae) di Pulau Jawa Woro Anggraitoningsih Noerdjito i Dilarang mereproduksi atau memperbanyak seluruh atau sebagian dari buku ini dalam bentuk atau cara apa pun tanpa izin tertulis dari penerbit. © Hak cipta dilindungi oleh Undang-Undang No. 28 Tahun 2014 All Rights Reserved ii Keanekaragaman KUMBANG STAG (Coleoptera: Lucanidae) di Pulau Jawa Woro Anggraitoningsih Noerdjito LIPI Press iii © 2016 Lembaga Ilmu Pengetahuan Indonesia Pusat Penelitian Biologi Katalog dalam terbitan Keanekaragaman Kumbang Stag (Coleoptera: Lucanidae) di Pulau Jawa/Woro Anggraitoningsih Noerdjito – Jakarta: LIPI Press, 2016. xxiv+148; 14,8 x 21 cm. ISBN 978-979-799-856-1 1. Keanekaragaman 2. Kumbang stag 595.764 9 Copy editor : M. Sidik Nugraha dan Sonny Heru Kusuma Proofreader : Sarwendah Puspita Dewi dan Fadly Suhendra Penata Isi : Erna Rumbiati, Prapti Sasiwi, dan Rahma Hilma Taslima Desainer sampul : Rusli Fazi Cetakan pertama : November 2016 Diterbitkan oleh: LIPI Press, anggota Ikapi Jln. Gondangdia Lama 39, Menteng, Jakarta 10350 Telp.: (021) 314 0228, 314 6942. Faks.: (021) 314 4591 E-mail: [email protected] Website: lipipress.lipi.go.id LIPI Press @lipi_press iv DAFTAR ISI DAFTAR GAMBAR .................................................................................vii DAFTAR TABEL ......................................................................................xv PENGANTAR PENERBIT.....................................................................xvii KATA PENGANTAR ...............................................................................xix
    [Show full text]
  • A Multilocus Assessment Reveals Two New Synonymies for East Asian
    ZooKeys 1021: 65–79 (2021) A peer-reviewed open-access journal doi: 10.3897/zookeys.1021.58832 RESEARCH ARTICLE https://zookeys.pensoft.net Launched to accelerate biodiversity research A multilocus assessment reveals two new synonymies for East Asian Cyclommatus stag beetles (Coleoptera, Lucanidae) Jiao Jiao Yuan1,2, Dan Chen1,2, Xia Wan1,2 1 Department of Ecology, School of Resources and Engineering, Anhui University, 111 Jiulong Rd., Hefei 230601, China 2 Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Hefei 230601, China Corresponding author: Xia Wan ([email protected]) Academic editor: A. Frolov | Received 26 September 2020 | Accepted 31 January 2021 | Published 2 March 2021 http://zoobank.org/23EF341F-3DAF-4D3C-8292-4AE87334E1B9 Citation: Yuan JJ, Chen D, Wan X (2021) A multilocus assessment reveals two new synonymies for East Asian Cyclommatus stag beetles (Coleoptera, Lucanidae). ZooKeys 1021: 65–79. https://doi.org/10.3897/zookeys.1021.58832 Abstract Cyclommatus scutellaris Möllenkamp, 1912, Cyclommatus elsae Kriesche, 1921 and Cyclommatus tam- daoensis Fujita, 2010 are East Asian stag beetle species with long-debated taxonomic relationships due to high intraspecific morphological variability. In this study, we applied multilocus phylogenetic analyses to reassess their relationships. Two mitochondrial genes (16S rDNA, COI) and two nuclear genes (28S rDNA, Wingless) were used to reconstruct the phylogeny through the Bayesian inference (BI) and Maxi- mum Likelihood (ML) methods. Both topologies supported two clades: the clade C. scutellaris was sister to the clade (C. elsae + C. tamdaoensis) with the subclade C. tamdaoensis embedded in the subclade C. elsae. The Kimura 2-parameter (K2P) genetic distance analysis yielded a low mean value (≤0.035) among the three taxa, which was well below the minimum mean value between other Cyclommatus species (≥0.122).
    [Show full text]
  • Original Research Articlethe Function of Appendage Patterning Genes In
    Developmental Biology 422 (2017) 24–32 Contents lists available at ScienceDirect Developmental Biology journal homepage: www.elsevier.com/locate/developmentalbiology Original research article The function of appendage patterning genes in mandible development of MARK the sexually dimorphic stag beetle ⁎ Hiroki Gotoha,b,c, , Robert A. Zinnab, Yuki Ishikawaa,d, Hitoshi Miyakawaa,e, Asano Ishikawaa,f, Yasuhiro Sugimea, Douglas J. Emleng, Laura C. Lavineb, Toru Miuraa a Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan b Department of Entomology, Washington State University, Pullman, WA 99164, USA c Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan d Graduate School of Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan e Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan f Division of Ecological Genetics, Department of Population Genetics, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan g Division of Biological Sciences, University of Montana-Missoula, MT 59812, USA ARTICLE INFO ABSTRACT Keywords: One of the defining features of the evolutionary success of insects is the morphological diversification of their Appendage patterning appendages, especially mouthparts. Although most insects share a common mouthpart ground plan, there is Exaggerated trait remarkable diversity in the relative size and shapes of these appendages among different insect lineages. One of Stag beetle the most prominent examples of mouthpart modification can be found in the enlargement of mandibles in stag Sexual dimorphism beetles (Coleoptera, Insecta). In order to understand the proximate mechanisms of mouthpart modification, we RNAi investigated the function of appendage-patterning genes in mandibular enlargement during extreme growth of the sexually dimorphic mandibles of the stag beetle Cyclommatus metallifer.
    [Show full text]
  • Heritability of Male Mandible Length in the Stag Beetle Cyclommatus Metallifer
    Title Heritability of male mandible length in the stag beetle Cyclommatus metallifer Author(s) Gotoh, Hiroki; Fukaya, Keiichi; Miura, Toru Entomological Science, 15(4), 430-433 Citation https://doi.org/10.1111/j.1479-8298.2012.00527.x Issue Date 2012-10 Doc URL http://hdl.handle.net/2115/53417 Rights The definitive version is available at wileyonlinelibrary.com Type article (author version) File Information ES15-4_430-433.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP Heritability of male mandible length in the stag beetle, Cyclommatus metallifer Hiroki GOTOH1 , Keiichi FUKAYA2 and Toru MIURA1 1 Laboratory of Ecological Genetics and 2 Laboratory of Animal Ecology, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan Correspondence: Toru Miura, Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan. Email: [email protected] 1 Abstract Numerous coleopteran species express male-specific “weapon traits” that often show size variations among males, even within a single population. Many empirical studies have demonstrated that environmental conditions during development affect absolute weapon size. However, relatively few studies in horned beetles support the hypothesis that the relationship between weapon size and body size, also referred to as a “scaling relationship” or “static allometry”, is largely determined by genetic factors. In this study, the heritability of absolute mandible length and static allometry between mandible length and body size were estimated in the stag beetle Cyclommatus metallifer. While no significant heritable variation was observed in absolute mandible length, high heritability (h2 = 0.57 ± 0.25) was detected in the static allometry between mandible length and body size.
    [Show full text]
  • Jaw Morphology and Fighting Forces in Stag Beetles Jana Goyens1,2,*, Joris Dirckx2 and Peter Aerts1,3
    © 2016. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2016) 219, 2955-2961 doi:10.1242/jeb.141614 RESEARCH ARTICLE Jaw morphology and fighting forces in stag beetles Jana Goyens1,2,*, Joris Dirckx2 and Peter Aerts1,3 ABSTRACT large and heavy musculature to bite their rivals forcefully. The jaws of different species of stag beetles show a large variety of Concomitantly, species with high bite forces probably needed to shapes and sizes. The male jaws are used as weapons in fights, and evolve a more robust jaw morphology to enable them to take a firm they may exert a very forceful bite in some species. We investigated in grip on rivals and to avoid mechanical failure (Goyens et al., 2015a). 16 species whether and how the forcefulness of their bite is reflected In sexually dimorphic stag beetle species, males with larger jaws in their jaw morphology. We found a large range of maximal muscle have higher mating rates than males with smaller jaws (Harvey and forces (1.8–33 N; factor of 18). Species investing in large bite muscles Gange, 2006; Lagarde et al., 2005; Okada and Hasegawa, 2005; also have disproportionately large jaw volumes. They use this Okada and Miyatake, 2006; Shiokawa and Iwahashi, 2000). Owing additional jaw volume to elongate their jaws, increasing their to their longer jaws, they can reach further forward in aggressive chances of winning in battles. The fact that this also decreases the battles to grab their opponent and to detach him from the substrate mechanical advantage is largely compensated for by elongated in- (Goyens et al., 2015b).
    [Show full text]
  • Biomechanics and Bite Forces of the Mandibles in the American Cockroach Periplaneta Americana
    RESEARCH ARTICLE Fast and Powerful: Biomechanics and Bite Forces of the Mandibles in the American Cockroach Periplaneta americana Tom Weihmann1*, Lars Reinhardt2, Kevin Weißing3, Tobias Siebert4, Benjamin Wipfler3* 1 Dept. of Zoology, University of Cambridge, Cambridge, United Kingdom, 2 Science of Motion, Friedrich Schiller University Jena, Jena, Germany, 3 Entomology Group, Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, Jena, Germany, 4 Institute of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany a11111 * [email protected] (TW); [email protected] (BW) Abstract Knowing the functionality and capabilities of masticatory apparatuses is essential for the OPEN ACCESS ecological classification of jawed organisms. Nevertheless insects, especially with their out- Citation: Weihmann T, Reinhardt L, Weißing K, standing high species number providing an overwhelming morphological diversity, are noto- Siebert T, Wipfler B (2015) Fast and Powerful: riously underexplored with respect to maximum bite forces and their dependency on the Biomechanics and Bite Forces of the Mandibles in mandible opening angles. Aiming for a general understanding of insect biting, we examined the American Cockroach Periplaneta americana. the generalist feeding cockroach Periplaneta americana, characterized by its primitive PLoS ONE 10(11): e0141226. doi:10.1371/journal. pone.0141226 chewing mouth parts. We measured active isometric bite forces and passive forces caused by joint resistance over the entire mandibular range with a custom-built 2D force transducer. Editor: Wulfila Gronenberg, University of Arizona, UNITED STATES The opening angle of the mandibles was quantified by using a video system. With respect to the effective mechanical advantage of the mandibles and the cross-section areas, we cal- Received: July 18, 2015 culated the forces exerted by the mandible closer muscles and the corresponding muscle Accepted: October 6, 2015 stress values.
    [Show full text]
  • The Evolutionary Ecology of Host-Microbiome Symbiosis In
    THE EVOLUTIONARY ECOLOGY OF HOST-MICROBIOME SYMBIOSIS IN ONTHOPHAGUS DUNG BEETLES Erik Stetson Parker Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Department of Biology, Indiana University February 2021 Accepted by the Graduate Faculty, Indiana University, in partial fulfillment of the requirements for the degree of Doctor of Philosophy Doctoral Committee ______________________________________ Armin P. Moczek, Ph.D. ______________________________________ Jen Lau, Ph.D. ______________________________________ Jay T. Lennon, Ph.D. ______________________________________ Irene L.G. Newton, Ph.D. ______________________________________ Whitney M. Schlegel, Ph.D. February 24th, 2021 ii ACKNOWLEDGEMENTS This dissertation would not have been possible without the help and support of many people. First, I would like to thank all the members of my committee: Jen, Jay, Irene, and Whitney. Your time, effort, and attention over the years have made me a better scientist and have made the work contained within this dissertation exponentially better than it would have been otherwise. Thank you all for sharing your valuable time with me, and more than anything thank you for caring. I would also like to thank all the past and present members of the Moczek lab for their support and shared expertise over these last six years. Being able to turn to all of you for help with projects when I needed it was almost as important as being able to turn to you all for distraction and entertainment when I was feeling burnt out. Thank you all for being there for me, and especially you, Anna. You were universally a great group of coworkers and I will look back on our time together fondly, even as I miss sharing my days with you all.
    [Show full text]