Center for Limnology, University of Wisconsin, Madison, WI 53201, USA.
FEMS Microbiol Ecol. 2011 Nov;78(2):336-48. doi: 10.1111/j.1574-6941.2011.01162.x. Epub 2011 Jul 29.
Recent studies indicate genetic diversity of cyanobacteria in eutrophic lakes is not represented well by culture collections or morphology. Yet, few studies have investigated genetic richness and evenness of cyanobacteria using culture-independent methods. We compared the genetic structure of cyanobacteria supported by four neighboring eutrophic lakes during the ice-free season. The partial phycobilincpcB/A genes plus intergenic spacer (PC-IGS) was used as a genetic marker.Sequences were phylogeneticallygrouped by maximum likelihood into genotypes representing sub-genera of the major taxa. Genotypes fell into genera commonly observed by microscopy in these lakes including Microcystis, Aphanizomenon, Chroococcus, Anabaena, and Cylindrospermopsis. Only three genotypes were shared among all four lakes, despite significant water flowage between lakes.A Parsimony P-test indicated lakes were significantly (p=0.01) clustered on the maximum likelihood tree. Pairwise differences using Unifrac distance were moderately or not significant. Analysis of molecular variance (AMOVA) indicated genetic variation among all genotypes (φ=0.06, p<0.001) and 94% of variability occurred within lakes rather than between lakes (6%), explaining the lack of pairwise differences between lakes. Lorenze curves of genotype abundance in each lake showed genetic structure was only moderately uneven (Gini coefficients of 0.37-0.5) indicating lakes did not support dominant genotypes. Overall, results from this study suggest diversity of cyanobacteria is shaped by heterogeneity within lakes (temporally or spatially) and relatively even population structures.
最近的研究表明，富营养化湖泊中的蓝藻的遗传多样性不能通过培养物集或形态学很好地代表。然而，很少有研究使用非培养方法调查蓝藻的遗传丰富度和均匀度。我们比较了四个相邻富营养化湖泊在无冰季节期间支持的蓝藻的遗传结构。使用部分藻蓝蛋白 cpcB/A 基因加基因间间隔（PC-IGS）作为遗传标记。通过最大似然法将序列按基因型进行系统发育分组，这些基因型代表主要分类群的亚属。基因型落入这些湖泊中通过显微镜常见观察到的属中，包括微囊藻、鱼腥藻、色球藻、束丝藻和柱孢藻。尽管湖泊之间有大量水流，但只有三种基因型在所有四个湖泊中共享。简约性 P-检验表明，湖泊在最大似然树上显著聚类（p=0.01）。使用 Unifrac 距离的成对差异不显著或不显著。分子方差分析（AMOVA）表明，所有基因型之间存在遗传变异（φ=0.06，p<0.001），94%的变异性发生在湖泊内而不是湖泊之间（6%），这解释了湖泊之间缺乏成对差异的原因。每个湖泊中基因型丰度的 Lorenz 曲线表明遗传结构仅适度不均匀（基尼系数为 0.37-0.5），表明湖泊不支持优势基因型。总体而言，本研究的结果表明，蓝藻的多样性是由湖泊内的异质性（时间或空间）和相对均匀的种群结构塑造的。
