Chiappero M B, Calderón G E, Gardenal C N
Cátedra de Química Biológica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Argentina.
Genetica. 1997;101(2):105-13. doi: 10.1023/a:1018399308323.
In species acting as hosts of infectious agents, the extent of gene flow between populations is of particular interest because the expansion of different infectious diseases is usually related to the dispersal of the host. We have estimated levels of gene flow among populations of the sigmodontine rodent Oligoryzomys flavescens, in which high titers of antibodies have been detected for a Hantavirus in Argentina that produces a severe pulmonary syndrome. Enzyme polymorphism was studied by means of starch gel electrophoresis in 10 populations from the area where human cases of Hantavirus have occurred. Genetic differentiation between populations was calculated from FST values with the equation Nm = [(1/FST) - 1]/4. To assess the relative importance of current gene flow and historical associations between populations, the relationship of population pairwise log Nm and log geographic distance was examined. Low FST (mean = 0.038) and high Nm (15.27) values suggest high levels of gene flow among populations. The lack of an isolation by distance pattern would indicate that this species has recently colonized the area. The northernmost population, located on the margin of a great river, shows very high levels of gene flow with the downstream populations despite the large geographic distances. Passive transport of animals down the river by floating plants would promote unidirectional gene flow. This fact and the highest mean heterozygosity of that northernmost population suggest it is a center of dispersal within the species' range.
在作为感染因子宿主的物种中，种群间基因流动的程度尤其令人关注，因为不同传染病的传播通常与宿主的扩散有关。我们估算了黄腹鼠（Sigmodontine rodent Oligoryzomys flavescens）种群间的基因流动水平，在阿根廷，已在该鼠种中检测到针对一种可引发严重肺部综合征的汉坦病毒的高滴度抗体。通过淀粉凝胶电泳研究了来自汉坦病毒人间病例发生地区的10个种群的酶多态性。利用公式Nm = [(1/FST) - 1]/4根据FST值计算种群间的遗传分化。为评估当前基因流动和种群间历史关联的相对重要性，研究了种群两两间log Nm与log地理距离的关系。低FST值（平均值 = 0.038）和高Nm值（15.27）表明种群间基因流动水平较高。缺乏距离隔离模式表明该物种最近才在该地区定殖。最北端的种群位于一条大河的边缘，尽管地理距离很远，但与下游种群显示出非常高的基因流动水平。漂浮植物将动物顺流被动运输会促进单向基因流动。这一事实以及该最北端种群最高的平均杂合度表明它是该物种分布范围内的一个扩散中心。
