Morfologická a genetická variabilita druhu Chydorus sphaericus (Crustacea, Cladocera) v závislosti na prostředí

Abstract

Úvod 5 ABSTRACT Genus Chydorus or more specifically the species of Chydorus sphaericus represents an extremely tolerant freshwater organism, which occurs in littoral zone of almost all kinds of aquatic habitats all over the world. It is usually associated with submerged macrophytes or substrate and also plays a key role in food webs of both vertebrate (fish) and invertebrate predators. Not only is this species in most localities the most common chydorid, but it is quite often the most common filtering cladoceran. Moreover, due to its little morphological variation most small globular representatives of the genus Chydorus were in the past all incorrectly ascribed to Chydorus sphaericus. However, thanks to more detailed studies it was suggested that so called species Chydorus sphaericus was not in fact a single taxonomic entity, but a group of several closely related species. It is clear today that for correct taxonomic desision it is necessary to combine all ecological, morphological, and genetic methods. The aim of this study was to explore genetical and morphological variation in populations of Chyrodis sphaericus from localities representing different sets of environmental factors. Four model localities were chosen: eutrophic ponds, temporary pools, mountain lakes and waterbodies affected by mining...