In Sub-Saharan Africa, Borassus aethiopum Mart. (African fan palm) is an important non-timber forest product-providing palm that faces multiple anthropogenic threats to its genetic diversity. However, this species is so far under-studied, which prevents its sustainable development as a resource. The present work is a first attempt at characterizing the genetic diversity and population structure of B. aethiopum across nine collection sites spanning the three climatic regions of Benin, West Africa, through the use of microsatellite markers. During a first phase we relied on the reported transferability of primers developed in other palm species. We find that, in disagreement with previously published results, only 22.5% of the markers tested enable amplification of B. aethiopum DNA and polymorphism detection is very low. In a second phase, we generated a B. aethiopum-specific genomic dataset through high-throughput sequencing and used it for the de novo detection of microsatellite loci. Among the primer pairs targeting these, 11 detected polymorphisms and were further used for analyzing genetic diversity. Across the nine sites, expected heterozygosity (He) ranges from 0.263 to 0.451 with an overall average of 0.354, showing a low genetic diversity. Analysis of molecular variance (AMOVA) shows that within-site variation accounts for 53% of the genetic variation. Accordingly, the low number of migrants and positive values of the fixation index (F) in sites from both the Central (Sudano-Guinean) and the Southern (Guinean) climatic regions suggest limited gene flow between sites. The global correlation between genetic and geographic distances is weak; however, our clustering analyses indicate that B. aethiopum palms from Savè (Center) are genetically more similar to those from the North than to samples from other Central sites. In the light of our results, we discuss the use of inter-species transfer vs. de novo development of microsatellite markers in genetic diversity analyses targeting under-studied species, and suggest future applications for our molecular resources. We propose that, while prominent short-range pollen and seed dispersal in Benin explain most of our results, gene flux between the Central and Northern regions, as a result of animal and/or human migrations, might underlie the Savè discrepancy.

中文翻译：

---

可移植性，简单序列重复（SSR）标记的开发及其在贝宁非洲扇形棕榈（Borassus aethiopum Mart。）的遗传多样性和种群结构分析中的应用

在非洲撒哈拉以南地区，Borossus aethiopum Mart。（非洲扇形棕榈）是一种重要的非木材林产品，其遗传多样性面临多种人为威胁。但是，到目前为止，该物种的研究还不足，这阻碍了其作为资源的可持续发展。目前的工作是通过使用微卫星标记物，在跨越西非贝宁三个气候区域的九个采集点上，表征棉衣芽孢杆菌的遗传多样性和种群结构的首次尝试。在第一阶段，我们依赖于在其他棕榈树种中开发的引物的报道可转移性。我们发现，与先前发表的结果不同，仅22.5％的测试标记物可扩增乙型芽孢杆菌DNA，且多态性检测非常低。在第二阶段，我们通过高通量测序生成了特定于乙硫杆菌的基因组数据集，并将其用于从头检测微卫星基因座。在针对这些的引物对中，有11种检测到多态性，并进一步用于分析遗传多样性。在这9个位点上，预期杂合度（He）在0.263至0.451之间，总体平均值为0.354，显示出较低的遗传多样性。分子变异分析（AMOVA）显示，位点内变异占遗传变异的53％。因此，来自中部（苏达诺-几内亚）和南部（几内亚）气候区域的地点的移民人数少且固定指数（F）为正值表明地点之间的基因流动有限。遗传距离与地理距离之间的全球相关性较弱；然而，我们的聚类分析表明，从Savè（中部）获得的B. aethiopum棕榈在遗传上与来自北部的棕榈相似，而不是来自其他中部站点的样品。根据我们的结果，我们讨论了针对研究不足的物种的遗传多样性分析中种间转移与从头开发微卫星标记的关系，并提出了分子资源的未来应用建议。我们建议，尽管贝宁的突出的短程花粉和种子传播解释了我们的大多数结果，但由于动物和/或人类迁徙的结果，中部和北部地区之间的基因流通可能是Savè差异的基础。我们讨论了针对研究不足的物种的遗传多样性分析中种间转移与从头发展微卫星标记之间的关系，并提出了我们分子资源的未来应用。我们建议，尽管贝宁的突出的短程花粉和种子传播解释了我们的大多数结果，但由于动物和/或人类迁徙的结果，中部和北部地区之间的基因流通可能是Savè差异的基础。我们讨论了针对研究不足的物种的遗传多样性分析中种间转移与从头发展微卫星标记之间的关系，并提出了我们分子资源的未来应用。我们建议，尽管贝宁的突出的短程花粉和种子传播解释了我们的大多数结果，但由于动物和/或人类迁徙的结果，中部和北部地区之间的基因流通可能是Savè差异的基础。