THE ORIGIN OF ALLIGATOR-SINENSIS

Alligator sinensis and alligator mississippiensis are put under the Al ligator family and Alligator genus as two different species and have b een thought that they are closely related in taxonomy. The results of our DNA-DNA hybridization experiments showed that A. sinensis is a rel atively young species originated in Asia, whereas A. mississippiensis is the older. It seems that the alligator and crocodilian could evolve from each other. The evolutionary rate of the crocodilian is slower t han those of birds and higher vertebrates. The phylogeny of four croco dilians have been obtained and the hypothesis that the ancestor of Cro codylus porosus is a transitional form between A. mississippiensis and A. sinensis is proposed.