Habitats

Predaceous diving beetles (Dytiscidae) are a highly speciose group of insects occurring in a large variety of habitat types, where they typically form multispecies assemblages, due to their high diversity and large variation in the degree of habitat specifi city. This chapter provides an overview of the characteristics of the main habitats where dytiscid species occur and summarizes the fi ndings of previous studies aimed at characterizing the contribution of various abiotic habitat conditions in determining patterns of dytiscid species distribution, including water fl ow, permanency, salinity, acidity, temperature, and habitat size. Emphasis is given to the description of various lentic and lotic habitats, and springs, along gradients of habitat permanency. Given increasing evidence of the importance of biotic interactions in determining the realized niche of many dytiscid species, this review describes briefl y the role of predation, food sources, and inter- and intraspecifi c competition as major habitat selection factors for certain dytiscid species. The signifi cance of the structure of the vegetation as a major habitat factor determining patterns in dytiscid species distribution is discussed and new insights on plant-dytiscid relationships are provided. Some of the issues associated with developing simple habitat classifi cations for dytiscid species are discussed. The main characteristics of some unique habitats where dytiscids form unique assemblages, such as groundwater and interstitial habitats, rock pools, hygropetric habitats, and phytotelmata are described.