中国水域江豚颅骨的地理变异

本文根据１４４号江豚骨骼标本（其中长江种群标本４０号，黄海种群标本５９号，南海种群标本４５号），选用４２项颅骨测量变量，研究了颅骨在各地理种群之间的差异。ｔ－检验和协方差分析表明：长江江豚成体的颅基长比较小。南海种群吻长小于其它两个种群，而吻宽则最大，长江种群次之，黄海种群最小。黄海种群的前颌骨宽、颧宽、眶前突最大宽和眶后突最大宽比其它两个种群的小。黄海种群的上颌齿较多，而南海种群则下颌齿较多，长

GEOGRAPHICAL VARIATIONS OF SKULL AMONG THEPOPULATIONS OF NEOPHOCAENA IN CHINESE WATERS

Geographical variations of skull among the Yangtze,Yellow Sea and South ChinaSea populations of the finless porpoise,Neophocaena phocaenoides,in Chinese waterswere studied using 42 skull measurements based on 144 specimens(40 from Yangtzepopulation,59 from Yellow Sea population and 45 from South China Sea population)deposited in the Cetacean Research Laboratory,Naijing Normal University. The t-testand covariance analysis(Tab.2)demonstrated that:Condylobasal length in the adultsof the Yangtze population was shorter than that of the other two populations(Fig. 1).The South China Sea population had shorter rostrum length(Fig.2a),but it had thelargest width of rostrum,the Yangtze population had the second,and the Yellow Seapopulation had the smallest(Fig,2b).The Yellow Sea population was smaller in thewidth of premaxillaries, zygomatic,preorbital(Fig. 2c)and postorbital.The South 168 China Sea population had more teeth on maxillaries while the Yellow Sea population hadmore teeth on mandibles.Tooth number of the Yangtze population was relatively small-er.The South China Sea population had also larger width of pterygoids(Fig.2d)andinterior nares,but smaller orbital length and preorbital length of lacrimal.The Yangtzepopulation had longer temporal fossa and periotic,wider occipital condyles. The discriminant analysis(Tab.3,Fig.3)showed that:1)Difference in the skullmeasurements among the three Chinese populations was demonstrated even forneonates;2)Difference between the South China Sea population and the other two waslarger than that between the Yangtze and Yellow Sea populations.3)The rostrumlength and rostrum width valued by previous authors were not the optimal group ofskull characters to distinguish the Chinese populations. Generally,the difference in theskull among different geographical populations was represented by a number of vari-ables. Although we have distinguished the populations using a few external measure-ments(reported in another paper),we could not do it using a few skull characters. Itimplies that in the course of population evolution,the osteological adaptation of Neopho-caena took place at a slower rate than the external morphology did.