长江水系鲢和草鱼遗传结构及变异性的RAPD研究

POPULATION STRUCTURE AND GENETIC DIVERSITY OF SILVER CARP AND GRASS CARP FROM POPULATIONS OF YANGTZERIVER SYSTEM REVEALED BY RAPD

采用随机扩增多态性DNA(RAPD)技术对长江中游的湖北嘉鱼与江西瑞昌两个地理群体和中游的汉江和湘江两大水系的鲢和草鱼的群体进行了遗传学研究。发现长江水系鲢的遗传变异要高于草鱼 ,与现今生物量成反比的反常现象。鲢遗传多样性从大到小的分布是嘉鱼→湘江→瑞昌→汉江。草鱼遗传多样性从大到小的分布是瑞昌→汉江→湘江→嘉鱼 ,鲢和草鱼的遗传多样性地理分布并不一致。遗传分化指数Gst分别为 1 2 3%和 1 7 5% ,表明鲢和草鱼的四个地理群体的遗传分化度较低 ,可能与地理位置较近和基因交流频繁有关。

Silver carp (Hypophthalmichthys molitrix Cuvier et Valenciennes) and grass carp (Ctenopharyngodon idellus Cuvier ct Valenciennes) are the most important farmed fishes in China. The seedlings of said species for aquaculture have came directly and indirectly from the Yangtze River because germplasm resources of silver carp and grass carp in this river is superior to those of other rivers. Therefore. genetic resources of silver carp and grass carp in the Yangtze River play a very important role in fisherics development in China in the long run. In present study, using RAPD (random amplified polymorphic DNA) technique we analyzed four populations. Two of them. namely, Jia-yu and Rui-chang which are from the middle reaches of Yangtze River, and the other two populations. namely, Han River and Xiang River which are from two branches of the middle reaches of the Yangtze River. Generally, genetic diversity in silver carp is higher than that of grass carp, but biomass of grass carp is higher than that of silver carp in the Yangtze River. The genetic diversity and biomass have negative relation, which is not consistent with most cases. The genetic diversity from highest to lowest in populations of silver carp is Jia-yu, Xiang River, Rui-chang and Han River population whereas in grass carp the genetic diversity from highest to lowest is Rui-chang. Han River. Xiang River and Jia-yu population. The population relationships of two specics are not consistent with each other. Gst for silver carp and grass carp is 12.3% and 17.5%, respectively, which indicated that genetic differentiation among populations in said two species is low. The reason for low genetic differentiation and population relationship may be due to sampling location, which are close to each other. The other reason may be due to frequent gene flow among populations.