Data from: Genetic connectivity and diversity in inselberg populations of Acacia woodmaniorum, a rare endemic of the Yilgarn Craton banded iron formations

Historically rare plant species with disjunct population distributions and small population sizes might be expected to show significant genetic structure and low levels of genetic diversity due to the effects of inbreeding and genetic drift. Across the globe terrestrial inselbergs are habitat for rich, often rare and endemic flora and are valuable systems for investigating evolutionary processes that shape patterns of genetic structure and levels of genetic diversity at the landscape scale. We assessed genetic structure and levels of genetic diversity across the range of the historically rare inselberg endemic Acacia woodmaniorum. Phylogeographic and genetic structure indicates that connectivity is not sufficient to produce a panmictic population across the limited geographic range of the species. However, historical levels of gene flow are sufficient to maintain a high degree of adaptive connectivity across the landscape. Genetic diversity indicates gene flow is sufficient to largely counteract any negative genetic effects of inbreeding and random genetic drift in even the most disjunct or smallest populations. Phylogeographic and genetic structure, a signal of isolation by distance, and a lack of evidence of recent genetic bottlenecks suggest long term stability of contemporary population distributions and population sizes. There is some evidence that genetic connectivity among disjunct outcrops may be facilitated by the occasional long distance dispersal of Acacia polyads carried by insect pollinators moved by prevailing winds.

历史上稀有的植物类群，若其种群呈间断分布（disjunct population）且种群规模较小，由于近交（inbreeding）与遗传漂变（genetic drift）的影响，往往会表现出显著的遗传结构（genetic structure）与较低的遗传多样性水平。全球范围内，陆地岛山（terrestrial inselbergs）是物种丰富且常伴生稀有、特有植物区系的生境，亦是探究景观尺度下塑造遗传结构模式与遗传多样性水平的进化过程的优质研究体系。本研究针对该稀有陆地岛山特有物种伍德曼相思树（Acacia woodmaniorum）的整个分布区，开展了遗传结构与遗传多样性水平的评估工作。系统地理学（phylogeographic）与遗传结构分析结果表明，即便在该物种有限的地理分布范围内，种群间的连通性也不足以形成泛交种群（panmictic population）。不过，历史时期的基因流（gene flow）水平足以维持景观尺度下较高的适应性连通性水平。遗传多样性分析结果显示，即便是在最为间断或种群规模最小的居群中，基因流也足以在很大程度上抵消近交与随机遗传漂变所带来的负面遗传效应。系统地理学与遗传结构特征、距离隔离（isolation by distance）信号，以及未检测到近期遗传瓶颈（genetic bottlenecks）的结果，均表明当前种群的分布格局与种群规模处于长期稳定状态。有证据表明，受盛行风（prevailing winds）携带的昆虫传粉者所传播的金合欢花粉块（Acacia polyads）偶尔发生长距离扩散，或可促进间断分布露头岩（outcrops）间的遗传连通性。