A Comparative Investigation of the Karyotypes From Four Amphibian Species

The karyotypes of four Amphibian species-Rana pleuraden Boulenger,R.catesbeiana (Shaw),R.japonica chaochiaoensis Liu,and Hyla annectans (Jerdon) were determined from metaphase of bone marrow or epithlinum cells from gut tissue prepared by the colchicine-hypotonic-air drying technique.The morphological criteria-relative length,arm-ratio and presence of secondary constriction permit the identification of each of the component parts.Three species of Genus Rana,like most other members of the Genus,have 26 chromosomes which divide into a group of five large pairs and a group of eight small pairs.Relative chromosomal lengths are similar in all three species.But the 10th chromosome of R.pleuraden have a secondary constriction in the long arm,while that of R.japonica chaochiaoensis are more than three.R.catesbeiana has only three.All the three species of Genus Rana have a large submetacentric chromosome,I.e.the 3rd chromosome.The above mentioned facts enable us to explain the homogenity of their evolution.The chromosomes of all the three species of genus Rana are meta- or submetacentric ones,without telo- or subtelocentric ones.Like other species of tree frog,Hyla annectans has 24 chromosomes which divide into a group of 5 large pairs and a group of 7 small pairs,a secondary constriction located in the long arm of the 9th chromosome.There is no evidence of an heteromorphic sex pair of chromosomes in these four species.