DNA extraction and ITS2 (internal transcribed spacer 2) gene sequences of some Brazilian freshwater copepods

摘要

Copepods, one of the most important plankton components in freshwater, are identified by small appendices and other morphological structures. But taxonomy based only on morphological structures results in imprecision and incorrectly identified organisms, which affects ecological studies such as biogeogra-phy, evolution, competition, and environmental bioindicators. New skills to increase accuracy in identification are required. Molecular biology can certainly con- tribute to understanding the ecological behavior of copepods. Some isolated efforts using molecular biology on freshwater copepods using molecular biology have been made by Wyngaard et al. (1995), Gr-ishanin et al. (1996) and Thum (2004), but as yet no coordinated effort has been made to identify markers and create a gene bank for these organisms. A gene bank would allow comparison of species from different continents, different subspecies, and species from impacted and non-impacted environments. Gene banks can also be powerful tools in evolutionary studies, as demonstrated by Giribet et al. (2001) and Regier & Shultz (2001) for the Arthropoda group, and Buklin et al. (1999) and Buklin & Kocher (1996) for oceanic Calanoida. The aim of this study is to present a methodology for Copepod DNA extraction, demonstrate variations of the ITS2 gene (internal transcribed spacer 2) among some freshwater Brazilian Calanoida and Cy-clopoida species, and propose a phylogenetic tree for these species.