1. Department of Zoology Faculty of Science, Charles University, Viničná 7, 128 44, Praha 2,Czech Republic
2. Department of Philosophy and History of Science, Faculty of Science, Charles University, Viničná 7, 128 44, Praha 2,Czech Republic
3. Department of Demography, Faculty of Science, Charles University, Albertov 6, 128 00, Praha 2,Czech Republic