Gene-associated microsatellite markers confi rm panmixia and indicate a diff erent pattern of spatially varying selection in the endangered Japanese eel Anguilla japonica

The Japanese eel(Anguilla japonica)is a commercially important fi sh species in East Asia and its recruitment has been rapidly declining since 1990s.Clarifying the genetic population structure of A.japonica is the basis of multinational cooperation on its management and protection,due to its large distribution range.Gene-associated markers have been proved powerful in delineating fi ne-scale population genetic structure and spatially varying selection.In the present study,we developed 24 polymorphic gene-associated microsatellite markers including 18 loci associated with the genes under selection in the two North Atlantic eel species(Anguilla anguilla and Anguilla rostrata)and 6 loci based on transcript sequences.A total of 13 geographic populations were sampled across its distribution range,including 11 samples from China(9 from China’s mainland and 2 from Taiwan region),and 2 samples from Japan.A total of 416 individuals(mostly glass eels)were collected and genotyped at the 24 microsatellites.All measures of diff erentiation were accordant with a panmictic scenario(F ST=-0.001)in A.japonica.No footprints of spatially varying selection were found,indicating that the selection pattern in A.japonica might be diff erent from that in the two North Atlantic eel species.We suggest that A.japonica should be managed as a single unit and management and conservation eff orts must be coordinated at the international level,as overexploitation in any region will decrease its recruitment across the whole distributional range.

峨边花牛的保存与利用刍议

峨边花牛是我国优良的肉役兼用品种,具有较好的肉用和役用性能,且适应性强,耐粗放,抗病力强等特点。近年来由于产区花牛与当地黄牛混群放牧及杂交等原因,使花牛品种特性的保存受到了威胁。因此,必须采取有效措施,确保这一宝贵资源不致丢失。根据保种理论和产区经济文化水平,花牛的保存宜按公:母为1:5的比例,建立核心群。采取保存与利用相结合,建立三级保种繁育体系,各家系等数留种,随机交配等措施,将每一世代近交系数增量控制在0.5％左右。