基于美国国立生物技术信息中心(National Center of Biotechnology Information,NCBI)中下载的43种石斛的全叶绿体组序列,对43个物种间的亲缘关系进行研究。结果显示:(1)叶绿体基因的碱基组成显示T、C、A、G碱基平均含量分别是31.8%、19.0%、30.7%、18.5%;(2)通过遗传距离分析发现,铁皮石斛、黄石斛、始兴石斛和铁皮石斛中科院Ⅳ号的遗传距离最小,为0。说明这4种石斛在遗传上比较近,与其他种之间亲缘关系均较远。(3)系统发育关系显示石斛属植物是一个单系群,其中梳唇石斛是最先分化出来的,其次是竹枝石斛;细茎石斛、霍山石斛、广东石斛具有较近的亲缘关系。
Amphioctopus fangsiao(Cephalopoda:Octopodidae)is an important commercial species in the coastal waters of China.In recent years,however,the resource of A.fangsiao have declined because of habitat destruction and overfishing.To analyze the genetic variations of A.fangsiao caused by the fluctuation of resources,the population genetic structure of nine sampling locations collected from the Bohai Sea to the South China Sea were investigated,using mtDNA COI fragments and microsatellite DNA.The results of F-statistics,AMOVA,STRUCTURE and PCA analyses showed three phylogeographic clades(Clades A,B and C),revealing limited genetic exchange between north and south populations.These clades diverged in 2.23(Clades A and B)and 3.67(Clades A,B and C)million years ago,during the dramatic environmental fluctuations,such as sea level and temperature changes,have exerted great influence on the survival distribution pattern of global organisms.Our results for low genetic connectivity among A.fangsiao populations provide insights into the development of management strategies,that is,to manage this species as separate management unit.
Dengue virus(DENV)is one of the most important arboviral pathogens in the tropics and subtropics,and nearly one-third of the world's population is at risk of infection.The transmission of DENV involves a sylvatic cycle between nonhuman primates(NHP)and Aedes genus mosquitoes,and an endemic cycle between human hosts and predominantly Aedes aegypti.DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four antigenically distinct serotypes(DENV-1-4).Phylogenetic analyses of DENV have revealed its origin,epidemiology,and the drivers that determine its molecular evolution in nature.This review discusses how phyloge-netic research has improved our understanding of DENV evolution and how it affects viral ecology and improved our ability to analyze and predict future DENV emergence.
