Data from: Cryptic species, native populations and biological invasions by a eucalypt forest pathogen

Human associated introduction of pathogens and consequent invasions are very evident in areas where no related organisms existed before. In areas where related but distinct populations or closely related cryptic species already exist, the invasion process is much harder to unravel. In this study, the population structure of the Eucalyptus leaf pathogen Teratosphaeria nubilosa was studied within its native range in Australia, including both commercial plantations and native forests. A collection of 521 isolates from across its distribution was characterized using eight microsatellite loci, resulting in 112 multilocus haplotypes (MLH). Multivariate and Bayesian analyses of the population conducted in STRUCTURE revealed three genetically isolated groups (A, B and C), with no evidence for recombination or hybridization among groups, even when they co-occur in the same plantation. DNA sequence data of the ITS (n=32), β-tubulin (n=32) and 27 anonymous loci (n=16) were consistent with microsatellite data in suggesting that T. nubilosa should be considered as a species complex. Patterns of genetic diversity provided evidence of biological invasions by the pathogen within Australia in the states of Western Australia and New South Wales, and helped unravel the pattern of invasion beyond Australia into New Zealand, Brazil and Uruguay. No significant genetic differences in pathogen populations collected in native forests and commercial plantations were observed. This emphasizes the importance of sanitation in the acquisition of nursery stock for the establishment of commercial plantations.在原本不存在相关病原生物的区域，由人类活动介导的病原引入及后续生物入侵现象十分显著。在已有近缘但分化种群或亲缘关系紧密的隐存种（cryptic species）的区域，入侵过程则更难解析。 本研究针对桉属（Eucalyptus）叶部病原菌Teratosphaeria nubilosa的种群结构，在其原生分布范围澳大利亚境内展开调研，覆盖商业人工林与原生林两类生境。研究收集了该菌全分布范围内的521株分离物，通过8个微卫星位点（microsatellite loci）进行基因分型，共获得112个多位点单倍型（multilocus haplotype，MLH）。利用STRUCTURE软件对种群开展的多元统计与贝叶斯分析结果显示，该菌可划分为3个遗传隔离的类群（A、B、C）；即便类群在同一人工林中共存，也未检测到类群间发生重组或杂交的证据。对内转录间隔区（ITS，n=32）、β-微管蛋白基因（β-tubulin，n=32）以及27个匿名位点（n=16）的DNA序列测序数据，与微卫星位点分析结果一致，均表明Teratosphaeria nubilosa应被视为一个物种复合群（species complex）。遗传多样性分布模式为该病原菌在澳大利亚境内西澳大利亚州与新南威尔士州的生物入侵事件提供了证据，并进一步解析了其从澳大利亚向新西兰、巴西及乌拉圭的入侵格局。未检测到原生林与商业人工林中的病原菌种群存在显著遗传差异。该结果凸显了在采购育苗材料以营建商业人工林时，做好检疫消毒工作的重要性。