Lucardi Rima D, Wallace Lisa E, Ervin Gary N
USDA Forest Service, Southern Research Station, Forestry Sciences Laboratory, 320 East Green Street, Athens, GA 30602, USA.
Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA.
Plants (Basel). 2020 Mar 31;9(4):423. doi: 10.3390/plants9040423.
The spatial expansions of invasive organisms in the novel range are generally expected to follow an isolation-by-distance relationship (IBD) if the invasion is biologically driven; however, many invasions are facilitated anthropogenically. This research focused on the extant expansion patterns of cogongrass (). Cogongrass is a widespread invasive species throughout the southern United States (US). Patterns of infestation vary among US states. Cogongrass is pyrogenic, and its invasion threatens softwood ( spp.) plantations, a substantial economic market for this US region. Over 600 individuals were sampled from seven invaded US states, using amplified fragment length polymorphisms (AFLPs) to assess genetic diversity and population structure. We suspected that differences in historical management efforts among US states influenced differences in genetic diversity and structure. We detected two genetic lineages at the highest level of analysis. One genetic lineage was locally restricted, whereas the other was found throughout the study region. Admixed individuals were found in all US states and consistently co-occurred with the dominant lineage, suggesting that secondary contact and hybridization may have facilitated expansion. The widespread prevalence of only one of the two detected genetic lineages suggests a primary genetic lineage responsible for on-going population expansion in the US.
如果入侵是由生物因素驱动的，那么新分布范围内入侵生物的空间扩张通常预期会遵循距离隔离关系（IBD）；然而，许多入侵是由人为因素促成的。这项研究聚焦于白茅（）的现有扩张模式。白茅是一种在美国南部广泛分布的入侵物种。美国各州的侵染模式各不相同。白茅易燃，其入侵威胁到针叶林（ spp.）种植园，而针叶林种植园是该美国地区的一个重要经济市场。从美国七个已入侵的州采集了600多个个体样本，利用扩增片段长度多态性（AFLP）来评估遗传多样性和种群结构。我们怀疑美国各州历史管理措施的差异影响了遗传多样性和结构的差异。在最高分析水平上我们检测到两个遗传谱系。一个遗传谱系局限于局部地区，而另一个在整个研究区域都有发现。在美国所有州都发现了混合个体，并且它们始终与优势谱系共同出现，这表明二次接触和杂交可能促进了扩张。所检测到的两个遗传谱系中只有一个广泛存在，这表明存在一个主要的遗传谱系，它是美国当前种群扩张的原因。
