Biodiversity Data Journal :
Data Paper (Biosciences)
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Corresponding author: Florian Leese (florian.leese@uni-due.de)
Academic editor: Davide Badano
Received: 17 Nov 2024 | Accepted: 29 Jan 2025 | Published: 21 Feb 2025
© 2025 Martina Weiss, Florian Leese
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Weiss M, Leese F (2025) Population genetic data (COI, ddRAD) of Sialis lutaria (Insecta, Megaloptera) from the Emscher catchment (Germany). Biodiversity Data Journal 13: e141997. https://doi.org/10.3897/BDJ.13.e141997
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In urban river systems, fragmentation of habitats and in-stream dispersal barriers play a major role in shaping the population genetic structure of freshwater macroinvertebrate species. In small, fragmented populations, effects of genetic drift and inbreeding are enhanced, which can lead to increased population differentiation and genetic diversity loss. One formerly strongly degraded and fragmented stream system in a highly urbanised area is the Emscher catchment in North Rhine-Westphalia, Germany. Major restoration efforts have led to an improvement of water and habitat quality over the past 20 years also in the formerly polluted tributaries, for example, the Boye catchment. However, the analysis of the population structure of two different amphipod and isopod species has revealed that some populations are still strongly isolated, indicating persisting gene flow barriers. In contrast, the effects are expected to be less pronounced in merolimnic species, which have an adult winged life stage, such as the alderfly Sialis lutaria (Linnaeus, 1758) . However, this species was much less abundant in the Boye catchment and not found in adjacent catchments (only 9 of 41 sampling sites), reducing the power of possible analyses.
As no population genetic studies of S. lutaria have to our knowledge been published so far and genetic resources are generally scarce for this species, we generated and present here population genetic data for 70 S. lutaria specimens for the mitochondrial cytochrome c oxidase I (COI) gene and, more importantly, high resolution genomic single nucleotide polymorphism (SNP) data for 71 specimens, generated with double-digest restriction site-associated sequencing (ddRAD-seq). These data can be valuable for further studies, analysing the population genetic structure, dispersal pathways and potential gene flow barriers for S. lutaria on a larger geographic scale. Additional to presenting the data, we also give first insights in the population structure on a small geographic scale (area of approx. 15 km2). While the population differentiation was generally low, as expected on this small scale, we still found that gene flow was not equally strong between all populations, but that one population played a central role as a source and sink population, which cannot only be explained by the distance between populations.
population genetic structure, gene flow, fragmentation, ddRAD, COI
The River Emscher catchment has been heavily impacted by urbanisation as it is located in one of the densest agglomerations in Europe, the “Ruhr Metropolitan Area” in the federal state of North Rhine-Westphalia in Germany (
In the overall project, we therefore aimed to analyse and compare the population genetic structure of different hololimnic species (i.e. Asellus aquaticus, Proasellus coxalis, Gammarus pulex and Gammarus fossarum) which differ in their pollution tolerance and dispersal capability and the merolimnic alderfly Sialis lutaria in different tributaries of the Emscher catchment, mainly Berne and Boye catchment. For all species, we sequenced the barcoding fragment of the cytochrome c oxidase I (COI) gene to check for the presence of potential cryptic species and obtain an overview over the population structure. Further, we generated high-resolution genome-wide SNP data using ddRAD-seq (double digest restriction site-associated DNA sequencing;
This dataset provides first insights into the small-scale population genetic structure of S. lutaria in the heavily urbanised and recently restored Boye catchment, which is part of the Emscher catchment in the Ruhr Metropolitan Area in western Germany. The generated COI, but especially the provided high-resolution ddRAD data, hold particular value for analyses of the population structure of this genetically understudied species on a larger scale. They can be used to gain more knowledge on the realised gene flow of this species in urban and rural areas.
The Emscher is a right tributary to the river Rhine and has a catchment area of 775 km2. It has several larger tributaries, for example, the Boye with a catchment area 75 km2, in which most of the sampling sites were located. While in the overall project, also sites in adjacent catchments were sampled (41 in total) which are described in detail in
The project was funded by a Forschungsgeist-Fellowship of the Stemmler-Stiftung within the Deutsches Stiftungszentrum (DSZ) (T0206/30095/2017) and supported by Collaborative Research Center (CRC) RESIST funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) 1439/1—project number: 426547801.
The sampling took place in 2019 and 2020 and in both years, larvae of S. lutaria were sampled using sieves and kick-nets. Specimens were then preserved in 96% denatured ethanol and stored at 4°C until further processing. S. lutaria was found at one near-natural and eight restored sampling sites (Table
Sampling sites with coordinates (WGS84), stream name (all sites Boye/Emscher catchment), ecological state and number of successfully analysed specimens per genetic marker.
site | coordinates | stream name | ecological state | COI | ddRAD | |||
latitude | longitude | 2019 | 2020 | 2019 | 2020 | |||
BO11 |
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Kirch-schemmsbach | restored 2007 | 4 | 8 | 4 | 7 |
BO12 |
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Kirch-schemmsbach | restored 2007 | 2 | 0 | 2 | 0 |
BO13 |
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Haarbach | restored 2011 | 6 | 6 | 6 | 5 |
BO14 |
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Haarbach | restored 2011 | 2 | 0 | 0 | 0 |
BO15 |
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Vorthbach | restored 2011 | 0 | 9 | 0 | 9 |
BO20 |
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Boye | restored 2002 | 0 | 0 | 1 | 0 |
BO21 |
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Boye | restored 2002 | 0 | 1 | 0 | 0 |
BO23 |
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Schöttelbach | near-natural | 7 | 8 | 9 | 9 |
BO25 |
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Boye | restored 2009 | 8 | 9 | 10 | 9 |
Sum | 29 | 41 | 32 | 39 |
Boye catchment belonging to the Emscher catchment which is located in the Ruhr Metropolitan Area in western Germany.
51.542215 and 51.579125 Latitude; 6.908860 and 6.960856 Longitude.
This dataset contains genetic data (COI, SNP data) for Sialis lutaria, Megaloptera.
Rank | Scientific Name | Common Name |
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species | Sialis lutaria | alderfly |
The final COI alignment included 70 specimens and had a length of 560 bp, containing five variable sites, which were all synonymous substitutions. In total, five different haplotypes were detected, of which two (H1 and H2) were common at all larger sampling sites, while the other three were only found in one specimen each and only in 2019 (Fig.
Population structure of S. lutaria in the Boye catchment. A COI minimum spanning network coloured according to sampling years. Vertical lines indicate mutations between haplotypes; B COI haplotype map showing the haplotype composition per site with sizes of pie charts scaled according to the numbers of sequences per site; C FST heat maps for the ddRAD data. Pairwise FST values are given above and the lower confidence intervals below the diagonal (values > 0 indicate significant differentiation, indicated in bold); D Relative migration network (GST) for the ddRAD dataset.
The ddRAD sequencing was successful for 71 of the 76 specimens and resulted in 4686 loci shared by at least 90% of the specimens. While the sNMF analysis indicated the presence of only one cluster, all populations (except BO20, n = 1) were significantly differentiated from each other, even though differentiation was low (Fig.
Even though not many sites and specimens could be analysed for S. lutaria and the population structure was generally low as expected over these short geographic distances (0.3 to 4.6 km air distance, 0.4 to 6.6 km waterway distance) for species with adult winged live stages, high resolution genomic data revealed that gene flow is not equally strong between all sites and not directly correlated to the distance between sites. Interestingly, the most upstream Boye site, which was restored in 2009 (BO25) was detected as a central node from and to which most of the gene flow occurred (i.e. a source and sink population) and not BO23 which is the only site located in a near-natural stream section. To understand the drivers of gene flow patterns, more data would be needed. However, the data presented here show that it would be interesting to further study connectivity in this species on small and larger geographic scales and that a high resolution can be obtained by using methods such as ddRAD already on a small geographic scale despite a generally high connectivity.
We thank Lea Heberle and Charlotte Frie for conducting the sampling in 2019, assisting in sampling in 2020 and helping with extraction of DNA (2019) and generation of COI sequences (2019, 2020). Further, we thank Dominik Buchner, for programming the pipetting robot and helping with sample procession on the robot. We thank the Emschergenossenschaft for information on and access to sampling sites.
The project was funded by a Forschungsgeist-Fellowship of the Stemmler-Stiftung within the Deutsches Stiftungszentrum (DSZ) (T0206/30095/2017). Additionally, this study was supported by Collaborative Research Center (CRC) RESIST funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) 1439/1—project number: 426547801.
We further acknowledge support by the Open Access Publication Fund of the University of Duisburg-Essen.
Information on ddRAD library preparation per sample, i.e. used adapter combinations and PCR success. Further, COI haplotype and NCBI accession numbers for the haplotype and the ddRAD BioSample are given. For specimens, where no ddRAD library was generated, COI haplotype information is also given.