ABSTRACT
Nonindigenous species pose a major threat for coastal and estuarine ecosystems. Risk management requires genetic information to establish appropriate management units and infer introduction and dispersal routes. We investigated one of the most successful marine invaders, the ctenophore Mnemiopsis leidyi, and used genotyping-by-sequencing (GBS) to explore the spatial population structure in its nonindigenous range in the North Sea. We analyzed 140 specimens collected in different environments, including coastal and estuarine areas, and ports along the coast. Single nucleotide polymorphisms (SNPs) were called in approximately 40 k GBS loci. Population structure based on the neutral SNP panel was significant (F ST .02; p < .01), and a distinct genetic cluster was identified in a port along the Belgian coast (Ostend port; pairwise F ST .02-.04; p < .01). Remarkably, no population structure was detected between geographically distant regions in the North Sea (the Southern part of the North Sea vs. the Kattegat/Skagerrak region), which indicates substantial gene flow at this geographical scale and recent population expansion of nonindigenous M. leidyi. Additionally, seven specimens collected at one location in the indigenous range (Chesapeake Bay, USA) were highly differentiated from the North Sea populations (pairwise F ST .36-.39; p < .01). This study demonstrates the utility of GBS to investigate fine-scale population structure of gelatinous zooplankton species and shows high population connectivity among nonindigenous populations of this recently introduced species in the North Sea. OPEN RESEARCH BADGES: This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at: The DNA sequences generated for this study are deposited in the NCBI sequence read archive under SRA accession numbers SRR6950721-SRR6950884, and will be made publically available upon publication of this manuscript.
ABSTRACT
Assessing population genetic structure is a crucial step to support fisheries and conservation management. DNA microsatellite molecular markers are a widely used tool in population genotyping. In the present study, we characterised and developed 14 novel polymorphic microsatellite markers for a decapod crustacean, the Atlantic seabob shrimp Xiphopenaeus kroyeri (Heller, 1862), through rapid and cost-effective Illumina shotgun sequencing and a Galaxy-based bioinformatic pipeline. We genotyped 60 individuals from 2 populations with the newly developed microsatellites, resulting in the detection of 3 to 29 alleles per locus. Four loci deviated from Hardy-Weinberg equilibrium. Cross-amplification in a cryptic congeneric species was successful for eight loci (57%). The microsatellite loci developed in this study will be highly relevant for genetic and evolutionary studies of X. kroyeri, and for the stock management of this commercially exploited species.