1. Department of Biology, Faculty of Education, Masaryk University, Brno, Czech Republic; e-mail: 328872@mail.muni.cz
2. Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Brno, Czech Republic; e-mail: 328868@mail.muni.cz
3. Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic; e-mail: martinkova@ivb.cz