High-resolution genetic analysis reveals extensive gene flow within the jellyfishPelagia noctiluca(Scyphozoa) in the North Atlantic and Mediterranean Sea

Abstract

Despite the importance of gelatinous zooplankton as components of marine ecosystems, both ecologically and socio‐economically, relatively little information is known about population persistence or connectivity in jellyfish. In the present study, we employed a combination of nuclear microsatellite markers and sequence data from the mitochondrial cytochrome oxidase I (COI) gene to determine levels and patterns of population genetic structuring in the holoplanktonic jellyfish Pelagia noctiluca across the northeast Atlantic Ocean and Mediterranean Sea. Our results indicate a high degree of connectivity in P. noctiluca, with little evidence of geographical structuring of genetic variation. A small but significant differentiation of Atlantic Ocean and Mediterranean stocks was detected based on the microsatellite data, but no evidence of differentiation was observed with the mtDNA, probably due to the higher power of the microsatellites to detect low levels of genetic structuring. Two clearly distinct groups of genotypes were observed within the mtDNA COI, which probably diverged in the early Pleistocene, but with no evidence of geographical structuring. Palaeodistribution modelling of P. noctiluca at the Last Glacial Maximum (LGM; c. 21 Kya) indicated large areas of suitable habitat south of the species’ current‐day distribution, with little reduction in area. The congruent evidence for minimal genetic differentiation from the nuclear microsatellites and the mtDNA, coupled with the results of the palaeodistribution modelling, supports the idea of long‐term population stability and connectivity, thus providing key insights into the population dynamics and demography of this important species.

Absence of spatial genetic structure in common dentex (Dentex dentex Linnaeus, 1758) in the Mediterranean Sea as evidenced by nuclear and mitochondrial molecular markers

“…Such absence of structure in a very large range, from the Aegean Sea to French Atlantic regions, is quite surprising for a coastal species. However similar homogeneity has been observed in coastal-lagoonal fish species [ 53 ], jellyfish [ 54 ] and in crustacean species [ 55 , 56 ], highlighting the probable importance of larval dispersal in a species range.…”

Implications for management and conservation of the population genetic structure of the wedge clam Donax trunculus across two biogeographic boundaries

“…On the other hand, the analysis of the genetic structure among samples from Atlantic Ocean and Mediterranean Sea of the European spiny lobster ( Palinurus elephas ) showed small but significant differences ( F ST for pairwise comparisons within basins = 0.003 ± 0.004 and F ST among basins = 0.011 ± 0.005) indicating the presence of two partially-overlapping groups (overlapping of some localities from the Atlantic and Mediterranean basins)40. In contrast, a recent study on the genetic structure the holoplanktonic jellyfish, Pelagia noctiluca , across the Atlantic Ocean and Mediterranean Sea indicated a high degree of connectivity with little evidence of population subdivision between basins41. A very small but significant differentiation ( F ST  = 0.005) among Atlantic and Mediterranean stocks was detected when using microsatellite allele frequencies but no evidence of differentiation was observed using mtDNA haplotype diversity.…”

Spatial heterogeneity of Pelagia noctiluca ephyrae linked to water masses in the Western Mediterranean

“…In the present study, the possible flux of P. noctiluca ephyrae towards the north would depend on the seasonality of the currents pattern and on the high mesoscale variability of hydrodynamic processes [14,17]. The entrance of individuals through the Strait of Gibraltar would be supported by the similar genetic structure between P. noctiluca from the North Atlantic and the Mediterranean, resulting from an extensive gene flow and a high degree of connectivity between both populations [87,88]. Following the main currents in the WM, and considering the lifespan of this species, between 9 months and 1 year [27,28], individuals entering through the Strait of Gibraltar, or their offsprings, could act as sink populations at different Mediterranean regions (e.g.…”