Abstract

Geographical variations of postcranial skeleton among the Yangtze, Yellow Sea and South China Sea populations of the finless porpoise, Neophocaena phocaenoides, in Chinese waters were studied with t-test, covariance analysis (Table 2) and stepwise discriminant analysis (Table 3,Fig. 2) using 42 measurements based on 142 specimens of all ages (38 from the Yangtze population, 59 from the Yellow Sea population and 45 from the South China Sea population) collected in 1974 to 1991 by the Cetacean Research Laboratory, Nanjing Normal University. The results showed that: (1) Geographical variations in the postcranial skeleton among the three Chinese populations were demonstrated in all the ages even for the neonates (Table 2,Fig. 2), but the differences were interpreted by a group of variances. No single difference could be used as a diagnostic character for subspecies identification. (2) Summary of the results of the comparison among the populations (Table 2 and 4) demonstrated that the postcranial skeleton in the South China Sea population was the most developed, that of the Yangtze population was the next, and that of the Yellow Sea population was the lowest. (3) Differences between the South China Sea and Yangtze populations were larger than that between the South China Sea and Yellow Sea populations, and therefore were the largest (Table 2 , Fig. 2). This is in agree with the result determined by external and skull measurements. (4) The degree of the difference and overlap in the measurements among different geographical populations implies that the adaptationary changes of the skull took place slower than those of the external morphology during the evolution of the finless porpoise populations, and those of the postcranial skeleton, in turn, slower than those of the skull.