Accurate taxonomic identification of alien species is crucial to detect new incursions, prevent or reduce the arrival of new invaders and implement management options such as biological control. Globally, the taxonomy of non-native Prosopis species is problematic due to misidentification and extensive hybridization. We performed a genetic analysis on several Prosopis species, and their putative hybrids, including both native and non-native populations, with a special focus on Prosopis invasions in Eastern Africa (Ethiopia, Kenya and Tanzania). We aimed to clarify the taxonomic placement of non-native populations and to infer the introduction histories of Prosopis in Eastern Africa. DNA sequencing data from nuclear and chloroplast markers showed high homology (almost 100 %) between most species analysed. Analyses based on seven nuclear microsatellites confirmed weak population genetic structure among Prosopis species. Hybrids and polyploid individuals were recorded in both native and non-native populations. Invasive genotypes of Prosopis juliflora in Kenya and Ethiopia could have a similar native Mexican origin, while Tanzanian genotypes likely are from a different source. Native Peruvian Prosopis pallida genotypes showed high similarity with non-invasive genotypes from Kenya. Levels of introduced genetic diversity, relative to native populations, suggest that multiple introductions of P. juliflora and P. pallida occurred in Eastern Africa. Polyploidy may explain the successful invasion of P. juliflora in Eastern Africa. The polyploid P. juliflora was highly differentiated from the rest of the (diploid) species within the genus. The lack of genetic differentiation between most diploid species in their native ranges supports the notion that hybridization between allopatric species may occur frequently when they are co-introduced into non-native areas. For regulatory purposes, we propose to treat diploid Prosopis taxa from the Americas as a single taxonomic unit in non-native ranges.

中文翻译：

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对全球入侵和分类学上有问题的树属Prosopis的遗传见解

准确地分类识别外来物种对于发现新的入侵，防止或减少新的入侵者的到来以及实施诸如生物控制等管理选择至关重要。在全球范围内，由于识别错误和广泛杂交，非本地Prosopis物种的分类存在问题。我们对几种Prosopis物种及其推定的杂种进行了遗传分析，包括本地和非本地种群，特别关注了东部非洲（埃塞俄比亚，肯尼亚和坦桑尼亚）的Prosopis入侵。我们的目的是弄清非本地人口的分类学位置，并推断Prosopis的引进历史在东部非洲。来自核标记和叶绿体标记的DNA测序数据显示，大多数被分析物种之间具有高度同源性（几乎100％）。基于七个核微卫星的分析证实了Prosopis物种之间的种群遗传结构较弱。杂种和多倍体个体在本地和非本地人群中均记录。肯尼亚和埃塞俄比亚的朱螺Prosopis juliflora入侵基因型可能具有相似的墨西哥本地血统，而坦桑尼亚的基因型可能来自不同的来源。秘鲁本土的Prosopis pallida基因型与来自肯尼亚的非侵入性基因型高度相似。相对于本地种群而言，引入的遗传多样性水平表明，多次引入的胡杨假单胞菌和P.淡紫发生在东部非洲。多倍体可能解释了东非对虾的成功入侵。多倍体P. juliflora与该属中的其他（二倍体）物种高度区分。大多数二倍体物种在其自然范围内缺乏遗传分化，这支持了以下观点：当异源物种共同引入非本地区域时，它们可能会频繁发生杂交。出于监管目的，我们建议将来自美洲的二倍体Prosopis分类单元视为非本地范围内的单个分类单元。