Two forms of A. halimus shrubs: erect habit (A. halimus) and bushy habit shrub (A. schweinfurthii) are used naturally isolated by a considerable distance from each other and occupy the same area. To explore the effect...Two forms of A. halimus shrubs: erect habit (A. halimus) and bushy habit shrub (A. schweinfurthii) are used naturally isolated by a considerable distance from each other and occupy the same area. To explore the effect of natural isolation on the genetic basis of the two forms, Start Codon Targeted (SCoT) and the phylogenetic relationships of A. halimus by sequencing ITS1-5.8S-ITS2 regions of the ribosomal DNA are used. Significant isolation-by-distance relationship was found (r = 0.62, P = 0.001). Soil factors did not influence molecular variations. The natural isolation of A. halimus habitats restricts gene flow among the populations and the observed high within-population genetic diversity (74.19%) in this species is best explained by its outcrossing behaviour, long-lived individuals and overlapping generations. The UPGMA analysis of the SCoT results showed that all the studied populations were divided into two discrete genetic groups with significant separation of the two forms in Burg El-Arab area (Populations 1 and 2) and insignificant separation between two forms in El-Hammam area (population 5 and 6). The sequencing of the ITS1-5.8S-ITS2 rDNA regions also showed the insignificant separation of the two A. halimus forms. We conclude that gene flow depending on habitat fragmentation was the main factor affecting the population genetic differentiation. We suggest that the two forms do not merit specific rank in presence of interference between the two forms and absence of a breeding barrier fail to separate the different populations when they become sympatric.展开更多
酵母的核糖体5.8 S rDNA及两侧的转录间隔区(ITS)具有显著的种间差异性,可以作为鉴别酵母菌种的分类依据.通过菌落PCR扩增该区域的DNA片段,用3种限制性内切酶CfoⅠ,HaeⅢ和HinfⅠ进行酶切,电泳分析酶切片段的长度多态性(RFLP),然后查找...酵母的核糖体5.8 S rDNA及两侧的转录间隔区(ITS)具有显著的种间差异性,可以作为鉴别酵母菌种的分类依据.通过菌落PCR扩增该区域的DNA片段,用3种限制性内切酶CfoⅠ,HaeⅢ和HinfⅠ进行酶切,电泳分析酶切片段的长度多态性(RFLP),然后查找数据库快速准确的鉴定酵母菌种.对本研究室保藏的12株酵母菌株进行分析,确认了已知种类的酿酒酵母(Saccha-romyces cerevisiaeAS 2.516)和路德类酵母(Saccharomycodes ludwigiiAS 2.243)的RFLP与数据库的信息完全一致,并对其余10株未知种类的酵母进行了菌种分类鉴定.展开更多
文摘Two forms of A. halimus shrubs: erect habit (A. halimus) and bushy habit shrub (A. schweinfurthii) are used naturally isolated by a considerable distance from each other and occupy the same area. To explore the effect of natural isolation on the genetic basis of the two forms, Start Codon Targeted (SCoT) and the phylogenetic relationships of A. halimus by sequencing ITS1-5.8S-ITS2 regions of the ribosomal DNA are used. Significant isolation-by-distance relationship was found (r = 0.62, P = 0.001). Soil factors did not influence molecular variations. The natural isolation of A. halimus habitats restricts gene flow among the populations and the observed high within-population genetic diversity (74.19%) in this species is best explained by its outcrossing behaviour, long-lived individuals and overlapping generations. The UPGMA analysis of the SCoT results showed that all the studied populations were divided into two discrete genetic groups with significant separation of the two forms in Burg El-Arab area (Populations 1 and 2) and insignificant separation between two forms in El-Hammam area (population 5 and 6). The sequencing of the ITS1-5.8S-ITS2 rDNA regions also showed the insignificant separation of the two A. halimus forms. We conclude that gene flow depending on habitat fragmentation was the main factor affecting the population genetic differentiation. We suggest that the two forms do not merit specific rank in presence of interference between the two forms and absence of a breeding barrier fail to separate the different populations when they become sympatric.
