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Genetic diversity and gene flow patterns in two riverine plant species with contrasting life-history traits and distributions across a large inland floodplain
Australian Journal of Botany ( IF 1.1 ) Pub Date : 2020-01-01 , DOI: 10.1071/bt20074
William Higgisson , Dianne Gleeson , Linda Broadhurst , Fiona Dyer

Gene flow is a key evolutionary driver of spatial genetic structure, reflecting demographic processes and dispersal mechanisms. Understanding how genetic structure is maintained across a landscape can assist in setting conservation objectives. In Australia, floodplains naturally experience highly variable flooding regimes that structure the vegetation communities. Flooding plays an important role, connecting communities on floodplains and enabling dispersal via hydrochory. Water resource development has changed the lateral-connectivity of floodplain-river systems. One possible consequence of these changes is reduced physical and subsequent genetic connections. This study aimed to identify and compare the population structure and dispersal patterns of tangled lignum (Duma florulenta) and river cooba (Acacia stenophylla) across a large inland floodplain using a landscape genetics approach. Both species are widespread throughout flood prone areas of arid and semiarid Australia. Tangled lignum occurs on floodplains while river cooba occurs along rivers. Leaves were collected from 144 tangled lignum plants across 10 sites and 84 river cooba plants across 6 sites, on the floodplain of the lower and mid Lachlan River, and the Murrumbidgee River, NSW. DNA was extracted and genotyped using DArTseq platforms (double digest RADseq). Genetic diversity was compared with floodplain-river connection frequency, and genetic distance (FST) was compared with river distance, geographic distance and floodplain-river connection frequency between sites. Genetic similarity increased with increasing floodplain-river connection frequency in tangled lignum but not in river cooba. In tangled lignum, sites that experience more frequent flooding had greater genetic diversity and were more genetically homogenous. There was also an isolation by distance effect where increasing geographic distance correlated with increasing genetic differentiation in tangled lignum, but not in river cooba. The distribution of river cooba along rivers facilitates regular dispersal of seeds via hydrochory regardless of river level, while the dispersal of seeds of tangled lignum between patches is dependent on flooding events. The genetic impact of water resource development may be greater for species which occur on floodplains compared with species along river channels.

中文翻译:

两种河流植物物种的遗传多样性和基因流动模式,在大型内陆漫滩中具有对比的生活史特征和分布

基因流是空间遗传结构的关键进化驱动因素,反映了人口过程和扩散机制。了解如何在整个景观中维持遗传结构有助于设定保护目标。在澳大利亚,洪泛区自然会经历高度可变的洪水制度,这些洪水制度构成了植被群落。洪水发挥着重要作用,连接洪泛平原上的社区并通过水力传播。水资源开发改变了漫滩河流系统的横向连通性。这些变化的一个可能后果是减少了物理和随后的遗传联系。本研究旨在使用景观遗传学方法识别和比较大型内陆漫滩中缠结木本植物 (Duma florulenta) 和库巴河 (Acacia stenophylla) 的种群结构和扩散模式。这两种物种在澳大利亚干旱和半干旱地区的洪水易发地区广泛分布。缠结的木质素出现在漫滩上,而库巴河则沿着河流出现。从 10 个地点的 144 株缠结木本植物和 6 个地点的 84 株库巴植物中收集叶子,这些植物位于拉克兰河下游和中部以及新南威尔士州穆伦比吉河的漫滩上。使用 DArTseq 平台(双消化 RADseq)提取 DNA 并进行基因分型。将遗传多样性与洪泛区-河流连接频率进行比较,将遗传距离(FST)与河流距离进行比较,站点之间的地理距离和洪泛区-河流连接频率。遗传相似性随着泛滥平原与河流连接频率的增加而增加,在缠结的木质素中,但在库巴河中没有。在缠结的木质素中,经历更频繁洪水的地点具有更大的遗传多样性,并且在遗传上更同质。还有距离效应的隔离,其中地理距离的增加与缠结木本植物的遗传分化增加相关,但与库巴河无关。无论河流水位如何,库巴河沿河流的分布都有助于通过水力定期传播种子,而斑块之间缠结的木本植物种子的传播取决于洪水事件。
更新日期:2020-01-01
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