Context

Black poplar (Populus nigra L.) is a keystone species of European riparian ecosystems that has been negatively impacted by riverside urbanization for centuries. Consequently, it has become an endangered tree species in many European countries. The establishment of a suitable rescue plan of the remaining black poplar forest stands requires a preliminary knowledge about the distribution of genetic variation among species populations. However, for some parts of the P. nigra distribution in Europe, the genetic resources and demographic history remain poorly recognized.

Aims

Here, we present the first study on identifying and characterizing the genetic resources of black poplar from the Oder valley in Poland. This study (1) assessed the genetic variability and effective population size of populations and (2) examined whether gene flow is limited by distance or there is a single migrant pool along the studied river system.

Methods

A total of 582 poplar trees derived from nine black poplar populations were investigated with nuclear microsatellite markers.

Results

(1) The allelic richness and heterozygosity level were high and comparable between populations. (2) The genetic structure of the studied poplar stands was not homogenous. (3) The signatures of past bottlenecks were detected.

Conclusion

Our study (1) provides evidence for genetic substructuring of natural black poplar populations from the studied river catchment, which is not a frequent phenomenon reported for this species in Europe, and (2) indicates which poplar stands may serve as new genetic conservation units (GCUs) of this species in Europe.

Key message

The genetic resources of black poplar in the Oder River valley are still substantial compared to those reported for rivers in Western Europe. On the other hand, clear signals of isolation by distance and genetic erosion reflected in small effective population sizes and high spatial genetic structure of the analyzed populations were detected. Based on these findings, we recommend the in situ and ex situ conservation strategies for conserving and restoring the genetic resources of black poplar populations in this strongly transformed by human river valley ecosystem.

中文翻译：

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波兰奥德河谷黑杨种群的有效种群规模低且空间遗传结构高

语境

黑杨（Populus nigra L.）是欧洲河岸生态系统的重要物种，几个世纪以来一直受到河滨城市化的负面影响。因此，它已成为许多欧洲国家中的濒危树种。要为剩余的黑杨林林分制定适当的救助计划，需要对物种种群之间遗传变异的分布有初步的了解。但是，对于欧洲黑夜蛾分布的某些地区，遗传资源和人口历史仍然知之甚少。

目的

在这里，我们提出了关于鉴定和表征波兰奥得河谷黑杨的遗传资源的第一项研究。这项研究（1）评估了遗传变异性和种群的有效种群大小，并且（2）研究了基因流是否受距离限制或沿研究的河流系统是否存在单个移民库。

方法

利用核微卫星标记对来自九个黑杨种群的总共582棵杨树进行了研究。

结果

（1）等位基因丰富度和杂合度水平很高，并且在人群之间具有可比性。（2）杨树林分的遗传结构不均一。（3）检测到过去瓶颈的特征。

结论

我们的研究（1）为所研究的河流集水区天然黑杨种群的遗传结构提供了证据，这在欧洲对该物种而言并不常见，并且（2）指出哪些杨树林可以作为新的遗传保护单位（欧洲的该物种的GCU）。

关键信息

与报道的西欧河流相比，奥德河谷的黑杨的遗传资源仍然丰富。另一方面，检测到的清晰的隔离距离和遗传侵蚀信号反映在所分析种群的小有效种群大小和高空间遗传结构中。基于这些发现，我们建议采用原位和非原位保护策略来保护和恢复这种由人类流域生态系统强烈转化的黑杨种群的遗传资源。