Phylogeny of Japanese Stag Beetles (Coleoptera: Lucanidae) Inferred from 16S mtrRNA Gene Sequences, with Reference to the Evolution of Sexual Dimorphism of Mandibles

Abstract

As a first step in reconstructing the phylogeny of world stag beetles (Coleoptera: Lucanidae), phylogenetic relationships among the major members of Japanese stag beetles were explored by analyzing a sequence of 1030 nucleotides from the mitochondrial 16S ribosomal RNA (16S rRNA) gene. A total of 20 species and three additional subspecies representing 13 genera were examined to provide basic information on the phylogeny of world Lucanidae. The resultant phylogenetic tree indicates that the family Lucanidae is monophyletic, and contains two major lineages: one consists of the genera Platycerus, Aesalus, Ceruchus, and Nicagus, and the other includes Dorcus, Rhaetulus, Prosopocoilus, Aegus, Neolucanus, Prismognathus, Lucanus, Figulus, and Nigidius. Generic members of the latter lineage are further divided into the following four sublineages: i) Figulus and Nigidius; ii) Prismognathus and Lucanus; iii) Aegus and Neolucanus; and iv) Dorcus, Rhaetulus, and Prosopocoilus. These molecular phylogenetic relationships are used as a basis for a preliminary exploration of the evolution of sexual dimorphism in the shape of the mandible. The results of this investigation suggest that strong sexual dimorphism with well-developed mandibles in males evolved independently at least twice, once in the genus Aegus and once in the ancestor of the Lucanus-Prismognathus and Dorcus-Rhaetulus-Prosopocoilus clades. Alternatively, it is possible that sexual dimorphism of mandibles has undergone secondary loss in the genera Figulus and Nigidius.

Biomechanical determinants of bite force dimorphism inCyclommatus metalliferstag beetles

“…During such fights, opponents try to grip each other and the winner will lift the other male and throw it backwards (Shiokawa and Iwahashi, 2000) (authors' personal observations; see supplementary material Movie 1). Male stag beetles with larger mandibles have been shown to win these male-male fights more often (Emlen et al, 2005;Hosoya and Araya, 2005;Tatsuta et al, 2001).…”

“…In order to assess the effects of male sexual dimorphism on function and performance, one should, ideally, compare with non-dimorphic conspecific males. In (stag) beetles, comparison with properly scaled females (see Materials and methods) can be used as a proxy for such a hypothetical nondimorphic male, as for species without sexual dimorphism (except for the reproductive organs), males and females can hardly (if at all) be discerned from each other (Hosoya and Araya, 2005;Kawano, 2006). We hypothesize that males show an increased bite force performance compared with females.…”

Molecular and Morphological Phylogenetic Analyses of New World Cycad Beetles: What They Reveal about Cycad Evolution in the New World

“…As seen in other arthropods, the 16S rRNA gene is highly AT-rich with average nucleotide frequencies of thymine (T) 42.9%, cytosine (C) 7.9%, adenine (A) 35.0%, and guanine (G) 14.3%. The 16S rRNA gene has been used widely in insect molecular systematics and its utility in discerning species groups and deeper divisions in beetles and other holometabolous insects is well-founded [34][35][36][37][38]. It has been proposed for use as a standard for insect phylogenetics [39].…”

Jaw morphology and fighting forces in stag beetles

“…Despite substantial scientific interest in the stag beetle family, the phylogeny of this large family (counting more than 1000 species) remains largely unknown (Hosoya and Araya, 2005;Kawano, 2000;Kim and Farrell, 2015). Therefore, a fully phylogenetically corrected statistical analysis (e.g.…”