Population genetics of the invasive ctenophore Mnemiopsis leidyi in Europe reveal source–sink dynamics and secondary dispersal to the Mediterranean Sea

Abstract

Repeated invasions of European waters by the ctenophore Mnemiopsis leidyi offer a unique opportunity to study population dynamics and dispersal in gelatinous zooplankton. Here we followed population establishment in 2 recently invaded areas, the North and Baltic Seas, and analysed changes in population structure during a 3 yr interval using 7 highly polymorphic microsatellites comprising 191 alleles. A second goal was to reconstruct routes of recent invasive range expansion into the Mediterranean Sea. During the study period (2008 to 2010), populations in the North Sea and Western Baltic Sea maintained their allelic composition with virtually unchanged levels of genetic diversity and between-population differentiation, demonstrating limited gene flow between the 2 regions and successful reproduction in both areas. In contrast, at the eastern distribution limit in the central Baltic (Bornholm Basin), the same measures fluctuated between years and genetic diversity decreased from 2008 to 2010. In concordance with prior ecological observations, this supports the view that M. leidyi in the central Baltic is a sink population. In the area of recent range expansion (Mediterranean Sea), we observed high population differentiation: pairwise differentiation (F ST ) values between sites in Spain, France and Israel were significant and between 0.04 and 0.16. Despite this differentiation, Bayesian clustering and phylogeographic analysis support the hypothesis that all Mediterranean M. leidyi result from a secondary introduction originating from the Black Sea. Our study contributes to growing evidence that multiple invasions of the same species can vary in their degree of genetic diversity and demonstrates how genetic markers can help to resolve whether gelatinous plankton species form self-sustaining populations.

Worldwide phylogeography of the invasive ctenophore Mnemiopsis leidyi (Ctenophora) based on nuclear and mitochondrial DNA data

“…Reusch et al (2010) and Ghabooli et al (2011) concluded that the Gulf of Mexico was the source for the Black Sea invasion while the northern M. leidyi European populations derived from samples at the northern extreme of the ctenophore's range, in New England. A third study using microsatellite data (Bolte et al 2013) indicated that the Mediterranean Sea regions were likely inoculated with animals from the Black Sea. Recently, Ghabooli et al (2013) examined variation in both mitochondrial cytochrome c oxidase I (COI) and nuclear ITS regions, indicating the possibility that Mediterranean populations may have been the result of independent invasion(s) in addition to introduction from the Black Sea.…”

Marine Biodiversity - Warming vs. Biological Invasions and overfishing in the Mediterranean Sea: Take care, ‘One Train can hide another’

“…The textbook case is the introduction in 1982 of one of the top 100 worst invasive species, according to IUCN, the ctenophore Mnemiopsis leidyi in the Black Sea through ballast waters. The introduction of this strong predator, native to the Gulf of Mexico [119,120], coincided with the collapse of local fisheries. Whether the introduction of this ctenophore is the reason for the collapse or just a collateral event that made things worse is still not clear.…”

Invasive ctenophore Mnemiopsis leidyi in Norway

“…Mnemiopsis leidyi exhibits pronounced source -sink dynamics with local extinctions at less favourable locations combined with repeated annual re-colonization from adjacent seed areas in both its native and introduced ranges (Purcell et al, 2001;Costello et al, 2006Costello et al, , 2012Bolte et al, 2013). During the non-reproductive period, advective losses can result in the disappearance of M. leidyi from large areas (Costello et al, 2006(Costello et al, , 2012.…”

“…Simultaneously, M. leidyi has also spread to the Mediterranean, most likely through secondary invasion from the Black Sea (Ghabooli et al, 2011;Bolte et al, 2013).…”