木瓜榕传粉榕小蜂与一种非传粉榕小蜂核型比较分析

Karyotype analysis of a pollinator, and a non-pollinator, of Ficus auriculata Loureiro

【目的】为了明确木瓜榕传粉榕小蜂Ceratosolen emarginatus Mayr及另外一种寄生于木瓜榕雌果内的非传粉小蜂Platyneura sp.染色体核型特征和差异。【方法】本研究采用小牛血清培养脑神经节的方法对寄生于木瓜榕Ficus auriculata Loureiro的两种小蜂进行了染色体核型比较分析。【结果】木瓜榕传粉小蜂的染色体数目为2n(♀)=10,染色体臂指数NF值为20,整个染色体组包含5对中着丝粒染色体,核型类别属Stebbins-1A型;非传粉小蜂Platyneura sp.的染色体数目为2n=12,染色体臂指数NF值为24,染色体组全部为中着丝粒染色体,核型类别属Stebbins-1A型。【结论】两种小蜂除染色体类型和核型类别相同,在其他染色体特征方面均表现出差异。结合前人和本研究结果,我们推测两种小蜂之间染色体核型可能发生了由传粉者向非传粉者的演化,即发生了染色体数目由少到多的演化。

[Objectives] In order to investigate the chromosomal karyotypes of two fig wasps, Ceratosolen emarginatusMayr, a pollinator of Ficus auriculata Loureiro, and a non-pollinating fig wasp Platyneura sp.. [Methods] The karyotype analysis of these species was performed using calf blood serum to culture cerebral ganglia of each species after dissection. [Results] Chromosomes of both wasps were metacentric and their karyotypes were Stebbins-1 A. Some differences between the two species were apparent, for example, the diploid chromosome numbers of C. emarginatus and Platyneura sp.were 2 n(♀)= 10 and 2 n(♀)= 12, respectively, and the corresponding arm numbers(NF) were 20 and 24. [Conclusion] Although the two species share the same chromosome type and karyotype, they differ in some other chromosome features. Taking into consideration the results of previous studies, it is possible that the karyotype of these two fig wasps may have evolved from pollinator to non-pollinator, i.e. that the number of chromosomes increased rather than decreased.