Genetic Control of Color Polymorphism in the Stag Beetle Cyclommatus metallifer Boisduval (Coleoptera: Lucanidae)

• Published in: The Coleopterists bulletin 2014-06, Vol.68 (2), p.209-213
• Main Authors: Gotoh, Hiroki, Lavine, Laura C
• Format: Article
• Language: English
• Subjects: Alleles; Animal morphology; autosomal control; backcrossing; Beetles; biology; Blacks; color; Dung beetles; genotype; Gold; hybrids; Insect genetics; Lucanidae; Male animals; males; Mendelian cross; paternity; Phenotypes; Phenotypic traits; population; predation; progeny; risk; Stag beetles; structural coloration
• ISSN: 0010-065X; 1938-4394
• DOI: 10.1649/0010-065X-68.2.209

We describe the genetic control of body color polymorphism in the metallic stag beetle, Cyclommatus metallifer Boisduval. As with many species of sexually dimorphic stag beetles, male C. metallifer exhibit condition-dependent exaggerated growth of mandibles. Another characteristic of this species is that two body colors have been described from both wild and captive bred populations. The two body colors are a commonly observed gold and a more rare black. We performed a simple Mendelian cross of individuals from families that produced only gold offspring to individuals from families that produced only blue-black offspring. All of the F1 hybrid progeny between these two pure gold families and pure black families exhibited the gold body color. The F2 progeny resulting from the crossing of F1 hybrids exhibited a 3:1 gold to black ratio. The backcross of the F1 hybrid to the gold morph resulted in 1:0 gold to black ratio. The backcross of the F1 hybrid to the black morph resulted in progeny with a 1:1 gold to black ratio. Our results show that the color polymorphism in the metallic stag beetle is under simple bi-allelic, autosomal control, and that the gold allele (G) is dominant to the black allele (g). The putative genotypes for the gold morph are GG and Gg and the blue-black morph is gg. Identification of this simple genetic mechanism for color polymorphism in the metallic stag beetle allows for future studies to use this trait as a marker in the investigation of evolutionary and ecologically relevant experiments such as those for male paternity, male mating success, and predation risk.