DOI: 10.5061/dryad.83bk3jb34
title: Data from: Levels and spatial patterns of effective population sizes in the southern damselfly (Coenagrion mercuriale): On the need to carefully interpret single-point and temporal estimations to set conservation guidelines

description: The effective population size (Ne) is a key parameter in conservation and
 evolutionary biology, reflecting the strength of genetic drift and
 inbreeding. While demographic estimations of Ne are logistically and
 time-consuming, genetic methods have become more widely used due to
 increasing data availability. Nonetheless, accurately estimating Ne
 remains challenging, with few studies comparing Ne estimates across
 molecular markers types and estimators such as single-sample methods based
 on linkage disequilibrium or sibship analyses versus methods based on
 temporal variance in allele frequencies. This study aims at bridging this
 gap by analysing single-sample and temporally-spaced populations in the
 southern damselfly (Coenagrion mercuriale), a bioindicator Odonata species
 of conservation concern found in southwestern Europe’s freshwater stream
 networks. 77 local populations were sampled from a semi-urbanised area
 located in eastern France near Strasbourg city, yielding 2,842 individuals
 that were genotyped with microsatellites, and 958 of which were also
 genotyped for 2,092 SNPs. Spatial genetic structure was stable over time,
 suggesting porosity between alternate-year cohorts. When accounting for
 spatial genetic structure, single-sample and temporal estimations of Ne
 were consistent for each set of molecular markers. Biologically meaningful
 results were obtained when the effect of migration was minimising by
 considering metapopulation Ne-estimates based on the level of genetic
 differentiation and population boundaries. In terms of applied
 conservation and management, most depicted metapopulations displayed large
 Ne, indicating no immediate need for conservation measures to mitigate
 anthropogenic pressures, provided that a continuous suitable freshwater
 network is maintained. However, urbanization negatively impacted Ne levels
 in populations close to Strasbourg city. Because Ne is used to inform
 conservation decisions, caution is crucial in interpreting Ne estimates,
 especially in continuously distributed populations undergoing migration.
 Altogether, our study highlights the challenge of obtaining robust Ne
 estimates and the necessity of careful interpretation to set relevant
 conservation guidelines.
description: # Levels and spatial patterns of effective population sizes in the
 southern damselfly (Coenagrion mercuriale): on the need to carefully
 interpret single-point and temporal estimations to set conservation
 guidelines
 [https://doi.org/10.5061/dryad.83bk3jb34](https://doi.org/10.5061/dryad.83bk3jb34) ## Description of the data and file structure -Microsatellite genotypes (samples locations and genotypes at 10 microsatellite loci) -2092 SNPs genotypes (samples locations and genotypes at 2092 SNPs loci) ### Files and variables #### File: Southern\_Damselfly\_Sample\_microsatellite\_genotype\_and\_locations.xlsx **Description:** Southern_Damselfly_Sample_microsatellite_genotype_and_locations.xlsx – File containing for each sample: the name of the individual (Sample_Name), the name of the site where it was sampled (ID_Site), the sampling year (Year), population location (Longitude_EPSG4326 [East], Latitude_EPSG4326 [North]), individual multilocus genotypes at 10 microsatellite loci. All individual samples were genotyped using ten unlinked nuclear microsatellite loci named LIST002, LIST023, LIST034, LIST035, LIST037, LIST042, LIST062, LIST024, LIST063, and LIST066, with forward and reverse primers initially isolated and described in Watts, P. C., Wu, J. H., Westgarth, C., Thompson, D. J., & Kemp, S. J., (2004) A panel of microsatellite loci for the Southern Damselfly, *Coenagrion mercuriale* (Odonata : Coenagrionidae). *Conservation Genetics*, **5**, 117-119). PCR reactions were performed in two multiplexes described in Table S2. PCR reactions were conducted in a volume of 10 µL, using 3 µL of DNA (0.5-5 ng/mL), 5 µL Multiplex PCR Master Mix (QIAGEN) and a primer mix (each primer at a final concentration of 0.2 µM). PCR amplifications were as follows: (i) 15 min at 95°C, (ii) 30 cycles for whole individuals, and 32 cycles for legs of 30 s denaturation at 94°C, 90 s annealing 55°C, and 60 s elongation at 72°C, (iii) 30 min at 60°C. 1.5 µL of  PCR products (1/10 diluted for whole individual samples) were pooled with 0.25 μL of RadiantDyTM 632 500 MOB size standard (Eurogentec, Seraing, Belgium) and 9.75 μL of formamide (Applied Biosystems, Foster City, CA), electrophoresed and sized with an ABI PRISM 3130XL sequencer (Applied Biosystems) and the software GeneMapper 5.0 software (Applied Biosystems). There is no missing data in this file. #### File: Southern\_Damselfly\_Sample\_2092SNP\_genotype\_and\_locations.xlsx **Description:** Southern_Damselfly_Sample_2092SNP_genotype.xlsx – File containing for each sample: the name of the individual (Sample_Name), the name of the site where it was sampled (ID_Site), the sampling year (Year), its location (Longitude_EPSG4326 [East], Latitude_EPSG4326 [North]), its genotype at the 2092 SNPs loci extracted from a genind genotype format as a matrix. Each sample is represented by a row, and each biallelic locus is encoded by two columns indicating the variant, with integers indicating the number of each allele, and summing up to the individuals' ploidy (2). Missing data are encoded by "NA".