Intraspecies mandible variation
Males of the same species often have differently shaped mandibles depending on body size. Some of these variations are inherited. Some are influenced by nutrition and the environment. Variations due to polymorphisms occur across different geographical groups. Variations due to phenotypic flexibility occur among individuals within a group. For example, in the ghost stag beetle (Odontolabis siva), the mandible shape is related to temperature. At lower temperatures, longer mandibles are produced. Moreover, variations in mandible size among large and small male Prosopocoilus inclinatus (Motschulsky) are due to nutritional status during the larval stage.
Images are of large and small male Prosopocoilus inclinatus (Motschulsky).
Specimen source: From the collection of the National Museum of Natural Science (donated specimens).
Image source: National Museum of Natural Science
