1. Department of Morphological Sciences, Warsaw University of Life Sciences, Nowoursynowska 159C, 02-776 Warsaw, Poland
2. Department of Biology of Animal Environment, Warsaw University of Life Sciences, Ciszewskiego 8, 02-787 Warsaw, Poland
3. Mathematical Statistics at the Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, ul. Banacha 2, 02-097 Warsaw, Poland