Inter-population variations in the sexual and intrasexual dimorphism in the earwig Labidura riparia (Dermaptera): a macroecological approach to patterns and process

• Grant number: 12/23135-6
• Support type: Scholarships in Brazil - Master
• Effective date (Start): June 01, 2013
• Effective date (End): February 28, 2015
• Field of knowledge: Biological Sciences - Ecology
• Principal researcher: Glauco Machado
• Grantee: Solimary García Hernández
• Home Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Intra-species sexual dimorphism occurs as a result of differing selection pressures on individuals of each sex. When the competition for access to females in a population is intense, it is possible for the males to display intra-sexual dimorphism. In arthropods, sexual and intra-sexual dimorphism is manifested not only in overall body size, but also in the phenotypic variation of weaponry. This phenotypic variability is determined by the intensity of competition for both mates and food resources, and the quality or quantity of food consumed by individuals during development. As a result, phenotypic dimorphisms, should be more prevalent in populations living in hot climates (tropical) than in those populations found in cold climates (temperate). This pattern should appear because in tropical regions with greater food availability not only provide more resources for investment in growing and competitive weaponry, but also a longer breeding season during which the synchrony of reproductive females is smaller and competition among males for access to receptive females is higher. In this project, we will study the patterns and processes underlying the inter-population variation in sexual and intra-sexual dimorphism, using the cosmopolitan earwig Labirura riparia (Dermaptera) as a model organism. We will first assess whether the intensity of sexual selection is greater in areas with tropical climates compared to temperate areas, performing a sampling of various populations along the east coast of South America. Second, through laboratory experiments, we will examine whether food availability determines the variation seen in the sexually selected traits of this species. The results from each phase of this project will, for the first time, allows us to understand how the intensity of sexual selection acts on a wide geographical scale. (AU)