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中国水域江豚颅骨的地理变异

高安利,周开亚   

  1. 南京师范大学生物系,南京
  • 出版日期:2006-07-29 发布日期:2008-07-07

GE0GRAPHICAL VARIAT10NS 0F SKULL AM 0NG THE P0PULAT10NS 0F NEOPHOCAENA IN CHINESE WATERS

GAO Anli, ZHOU Kaiya   

  • Online:2006-07-29 Published:2008-07-07

摘要: 本文根据144号江豚骨骼标本(其中长江种群标本4o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一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,而吻竟则最大,长江种群次之,黄海种群最小。黄海种群的前颤骨竟、颧竟、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,长江种群的牙齿数相对最少。南海种群还有明显较宽的翼骨和内鼻孔以及较短的眼眶长和泪骨眶前突长。长江种群有较长的颞窝、鼓围耳骨和较宽的枕髁。判别分析表明,1)中国水域江豚不同种群之间在颅骨上的差异是明显的;2)南海种群与其它两个种群的差异相对较大,黄海种群与长江种群差异较小;3)吻长和吻宽等并非区别中国水域江豚不同种群的最佳颅骨性状组合;4)江豚种群分化过程中,骨骼系统发生的适应性变化比其外形的变化要慢。

关键词: 江豚, 种群, 颅骨, 地理变异

Abstract: Geographical variations of skull among the Yangtze,Yellow Sea and South China
Sea 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,Nanjing 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 Southchina Sea population had more teeth on maxillaries while the Yellow Sea population hadmore teeth on mandibles.Tooth number of the Yangtze population was relatively smaller.The South China Sea population had also larger width of pterygoids(Fig.2d)and interior nares,but smaller orbital length and preorbital length of lacrima1.The Yangtzepopulation had longer temporal fossa and periotic,wider occipital condyles.
The discriminant analysis(Tab.3,Fig.3)showed that:1)Difference in the skull
measurements among the three Chinese populations was demonstrated even for
neonates;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 variables.Although we have distinguished the populations using a few external measurements (reported in another paper),we could not do it using a few skull characters. Itimplies that in the course of population evolution,the osteologieal adaptation of Neophocaena took place at a slower rate than the external morphology did.

Key words: Neophocaena, population}skull, geographical variation