中国孤雌卤虫的比较形态学与分子系统学研究

【摘要】：The brine shrimp Artemia (Crustacea:Anostraca) is a typical cosmopolitan zooplankton that has been adapted to live in widely range of salinity with different ionic compositions. The genus Artemia Leach,1819 is composed of seven bisexual species and numerous parthenogens populations. In the present study biometrical, morphological and genetic characteristics of Chinese parthenogenetic Artemia were analyzed.The results demonstrate that biometrical characters of cysts have positive statistical correlation together (p 0.05). Meanwhile, the ploidy levels of parthenogenetic Artemia can not be taken to be only one cause of size variation, others being such things as interaction with population-specifics, biotic and abiotic parameters. The present study considered high-altitude habitat influences on the diameter of cysts and their coloration. So it can be concluded that native bisexual and parthenogenetic populations of Artemia living at very high altitudes will have large cysts and also thick chorions, as well as dark shells.The surface decorations of nine cysts of Chinese parthenogenetic Artemia were studied by scanning electron microscope. With regard to the topography of cyst shells,15 different morphological patterns were recognized. There is no relationship the diversity of cyst shell patterns and ploidy compositions. No positive correlation between the diversity of cyst shell patterns and ploidy compositions was found. Principal components analysis indicates coastal populations have higher similarity of shell morphology than inland populations.Seven Chinese parthenogenetic Artemia with different elevation levels of locations and various ploidies are characterized by phenotypic and morphometric analysis. The results show that all studied populations explained dissimilar patterns of ovisac. Four shapes of furca are qualified and one of them is shared among di-, tetra- and pentaploid Artemia. With regard to discriminant analysis, tetra- and pentaploid populations were grouped together and mainly diploid Aqqikkol Lake Artemia is clearly differentiated. Triploid Aibi Lake Artemia and Aqqikkol Lake population don't fallow the relationship of ploidy degrees and body size.An Artemia specimen showing a new pattern of gynandromorphic morphology was found in a parthenogenetic Artemia cultured population from Ga Hai, Qinghai. The specimen included two male second antennae and bilaterally gynandromorphic in genital segments with the right side bearing a half ovisac and the left side a single penis.Two nuclear (ITS1 and Na+/K+ ATPase) and tree mitochondrial (COI,16S and 12S) markers were used to determined the genetic variation and evolutionary relationship between parthenogenetic and Asian bisexual Artemia. The phylogenetic results prove that parthenogenetics Artemia are polyphyletic groups, in which the diploids and triploids are maternally closely related to Artemia urmiana while tetraploids and pentaploids share a common ancestor with Artemia sinica. Some parthenogens presented heterozygote pattern in third position of valine codon in the exon-7 of the Na+/K+ ATPase a-1 subunit nuclear gene so it can not be universal barcode to discriminate between parthenogenetic populations and sexual species.