Brisson Dustin, Dykhuizen Daniel E
Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794-5245, USA.
Genetics. 2004 Oct;168(2):713-22. doi: 10.1534/genetics.104.028738.
The outer surface protein C (ospC) locus of the Lyme disease bacterium, Borrelia burgdorferi, is at least an order of magnitude more variable than other genes in the species. This variation is classified into 22 ospC major groups, 15 of which are found in the northeastern United States. The frequency distributions of ospC within populations suggest that this locus is under balancing selection. In multiple-niche polymorphism, a type of balancing selection, diversity within a population can be maintained when the environment is heterogeneous and no one genotype has the highest fitness in all environments. Genetically different individuals within vertebrate species and different vertebrate species constitute diverse environments for B. burgdorferi. We examined four important host species of B. burgdorferi and found that the strains that infected each species had different sets of ospC major groups. We found no variation among conspecific hosts in the ospC major groups of their infecting strains. These results suggest multiple niches create balancing selection at the ospC locus.
莱姆病细菌伯氏疏螺旋体（Borrelia burgdorferi）的外表面蛋白C（ospC）基因座的变异程度比该物种中的其他基因至少高一个数量级。这种变异被分为22个ospC主要组，其中15个在美国东北部被发现。种群内ospC的频率分布表明该基因座处于平衡选择之下。在多生态位多态性（一种平衡选择类型）中，当环境异质且没有一种基因型在所有环境中都具有最高适应性时，种群内的多样性可以得到维持。脊椎动物物种内基因不同的个体以及不同的脊椎动物物种为伯氏疏螺旋体构成了多样的环境。我们研究了伯氏疏螺旋体的四种重要宿主物种，发现感染每种物种的菌株具有不同的ospC主要组。我们发现同种宿主感染菌株的ospC主要组之间没有差异。这些结果表明多个生态位在ospC基因座上产生了平衡选择。
