Genetic patchiness in European eel adults evidenced by molecular genetics and population dynamics modelling

Abstract

a b s t r a c tDisentangling the demographic processes that determine the genetic structure of a given species is a fundamental question in conservation and management. In the present study, the population structure of the European eel was examined with a multidisciplinary approach combining the fields of molecular genetics and population dynamics modelling. First, we analyzed a total of 346 adult specimens of known age collected in three separate sample sites using a large panel of 22 EST-linked microsatellite loci. Second, we developed a European eel-specific model to unravel the demographic mechanisms that can produce the level of genetic differentiation estimated by molecular markers. This is the first study that reveals a pattern of genetic patchiness in maturing adults of the European eel. A highly significant genetic differentiation was observed among samples that did not follow an Isolation-by-Distance or Isolation-by-Time pattern. The observation of genetic patchiness in adults is likely to result from a limited parental contribution to each spawning event as suggested by our modelling approach. The value of genetic differentiation found is predicted by the model when reproduction occurs in a limited number of spawning events isolated from each other in time or space, with an average of 130-375 breeders in each spawning event. Unpredictability in spawning success may have important consequences for the life-history evolution of the European eel, including a bet-hedging strategy (distributing reproductive efforts over time) which could in turn guarantee successful reproduction of some adults.

Ecological traits shape genetic diversity patterns across the Mediterranean Sea: a quantitative review on fishes

“…Due to the absence of obvious barriers, it has been assumed that there were low levels of differentiation in most marine species (Ward et al ., ; Waples, ; Hellberg et al ., ). However, several recent studies have shown that marine populations are more isolated than previously thought (Bahri‐Sfar et al ., ; Cowen et al ., ; Debes et al ., ; Galarza et al ., ; Selkoe et al ., ; Pujolar et al ., ), thus the potential gene flow homogenizing genetic diversity across subpopulations may not be as strong as formerly believed, particularly in fragmented seascapes. The Mediterranean Sea is the archetypal situation where fish species may have isolated subpopulations given the highly tortuous coast with some local semi‐enclosed seas (e.g.…”

Swept away: ocean currents and seascape features influence genetic structure across the 18,000 Km Indo-Pacific distribution of a marine invertebrate, the black-lip pearl oyster Pinctada margaritifera

“…shape and size), as well as sampling strategy [1, 5, 10]. While not all of these may apply to marine scenarios, for taxa that employ a broadcast spawning reproductive strategy, consideration of the extent of ocean current-mediated larval dispersal addresses many of these points [4, 23–26]. …”

Detecting genome-wide gene transcription profiles associated with high pollution burden in the critically endangered European eel

“…Philopatry to a single spawning ground and an extensive migration loop with great opportunity for mixing of individuals might explain the homogeneity in genetic composition between geographic areas across Europe, suggestive of a panmictic population (Dannewitz et al, 2005;Als et al, 2011). The observation of a smallscale pattern of genetic patchiness among intra-annual (arrival waves) samples does not conflict with the lack of large-scale geographic substructuring but it is most likely a consequence of a large variation in reproductive success (Pujolar et al, 2006(Pujolar et al, , 2007(Pujolar et al, , 2011a.…”