Geographic Patterns in Soil Bacteria

土壤中蕴藏着种类繁多的微生物，其中大多数尚未被发现。了解这种生物多样性的范围和模式的一个关键组成部分是是否存在地理上独特的种群。一个世纪以来的教条认为，自由生活的细菌遍布全球，因为微生物可以通过风、鸟和人类传播。我们建议重新评估这一原则，因为了解地理种群模式是否存在对许多基础和应用问题都很重要，这些问题包括理解生物多样性、生态作用、检疫和药物发现的新策略。我们建议使用我们现有的重要土壤细菌群（荧光假单胞菌）的收集来测试细菌地方性假设。这些分离株来自6个不同大陆地区的5个不同地点的200万样地未受干扰的土壤。我们建议使用一套分子方法来评估地方性的程度，这些方法将提供群体遗传分辨率的连续体。如果遗传距离随着地理距离的增加而增加，如果基因的系统发育分析显示出地理分支，则该假设将得到支持。

Tiedje, JamesABSTRACT #DEB0075564 Soil harbors a tremendous diversity of microbes, most undiscovered. A key component to understanding the extent and patterns of this biodiversity is whether or not there are geographically unique populations. Century old dogma states that free-living bacteria are globally dispersed since microbes can be transported by wind, birds and humans. We propose to reevaluate this principle since understanding whether geographic population patterns exist is important to a number of basic and applied issues ranging from understanding biological diversification, to ecological roles, to quarantine, to new strategies for pharmaceutical discovery. We propose to test the bacterial endemism hypothesis using our existing collection of an important soil bacterial group (fluorescent Pseudomonas). These isolates are from undisturbed soil taken from 200m transects, at five different sites in each of six different continental regions. We propose to evaluate the degree of endemicity using a suite of molecular methods that will provide a continuum of genetic resolution of the population. The hypothesis will be supported if genetic distance increases with geographic distance, and if the phylogenetic analysis of genes shows geographic clades.