The karyotypes of 15 species of snakes are described: Lachesis muta noctivaga, Micrurus lemniscatus carvalhoi, Philodryas aestivus aestivus, P. patagoniensis, P. serra, Thamnodynastes pallidus nattereri, T. strigatus, Tomodon dorsatus, Xenodon neuiviedii, Liophis miliaris, Erythrolamprus aesculapii venustissimus, Hydrodynastes bicinctus schultzi, H. gigas, Pseustes sulphureus sulphureus and Oxyrhopus petolarius. The diploid number varied from 24 to 46 between species of the family Colubridae. During evolution, variation of the chromosome number in the suborder Serpentes occurred mostly by rearrangements of genetic material rather than by alterations of the DNA amount. Different stages of heteromorphic sex-chromosome differentiation were detected in the species analyzed; these ranged from absence of heteromorphism in either sex to striking differences in form and size of the sex heterochromosomes in the female.
展开▼
