What can gene flow and recruitment dynamics tell us about connectivity between European hake stocks in the Eastern North Atlantic?

Shallow population structure is generally reported for most marine fish and explained as a consequence of high dispersal, connectivity and large population size. Targeted gene analyses and more recently genome-wide studies have challenged such view, suggesting that adaptive divergence might occur even when neutral markers provide genetic homogeneity across populations. Here, 381 SNPs located in transcribed regions were used to assess large- and fine-scale population structure in the European hake (Merluccius merluccius), a widely distributed demersal species of high priority for the European fishery. Analysis of 850 individuals from 19 locations across the entire distribution range showed evidence for several outlier loci, with significantly higher resolving power. While 299 putatively neutral SNPs confirmed the genetic break between basins (F(CT) = 0.016) and weak differentiation within basins, outlier loci revealed a dramatic divergence between Atlantic and Mediterranean populations (F(CT) range 0.275-0.705) and fine-scale significant population structure. Outlier loci separated North Sea and Northern Portugal populations from all other Atlantic samples and revealed a strong differentiation among Western, Central and Eastern Mediterranean geographical samples. Significant correlation of allele frequencies at outlier loci with seawater surface temperature and salinity supported the hypothesis that populations might be adapted to local conditions. Such evidence highlights the importance of integrating information from neutral and adaptive evolutionary patterns towards a better assessment of genetic diversity. Accordingly, the generated outlier SNP data could be used for tackling illegal practices in hake fishing and commercialization as well as to develop explicit spatial models for defining management units and stock boundaries.

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“…; Pita et al . ) and newly assessing the divergence of Northern Sea hake from the southernmost Atlantic demes.…”

Section: Discussionmentioning

confidence: 99%

Outlier SNP markers reveal fine‐scale genetic structuring across European hake populations (Merluccius merluccius)

Babbucci²,

et al. 2013

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“…For instance, a number of individuals collected in the Celtic Sea were assigned to the groups dominated by southern stock local populations while some individuals collected on the Galician Shelf were grouped with the northern stock. Several population genetic studies have similarly shown that there are no significant genetic divergences between the northern and southern stocks of hake within in the northeast Atlantic (Roldán et al, 1998;Castillo et al, 2005;Pita et al, 2011). Taken together, these movement patterns do not support the management boundary established in the Atlantic Ocean to separate the European hake stocks but rather advocate for a re-evaluation of the most adequate and effective management units for the species due to the high complexity of European hake population structure.…”

Section: Discussionmentioning

confidence: 86%

“…Based on recent studies of population genetics, there appears to be some movement between the two stocks (e.g. Pita et al, 2011). However, there is at present a lack of data to quantify the extent and rate of exchange between the putative stocks.…”

Section: Introductionmentioning

confidence: 97%

Testing an otolith geochemistry approach to determine population structure and movements of European hake in the northeast Atlantic Ocean and Mediterranean Sea

et al. 2012

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“…We selected a long-term exploited species in the Eastern Atlantic (European hake, Merluccius merluccius; see Plate 1) that exhibits a complex spatial structure with two main demes consistent with two current management units (i.e., stocks). These demes are not genetically different (Pita et al 2011) but display spatially independent and temporally stable spawning aggregations (Fig. 1a), and distinct recruitment dynamics (Hidalgo et al 2012; see also Material and Methods).…”

Section: Introductionmentioning

confidence: 94%

“…1. (a) Area covered by the north (NA, black square) and south (SA, gray square) management units of hake investigated as independent demes (Pita et al 2011). Light and dark gray areas of the ocean indicate the main nursery and spawning areas, respectively; GS and CS refer to Galician shelf and Celtic Sea (see Materials and Methods for study system description).…”

Section: Introductionmentioning

confidence: 99%

Contrasting evolutionary demography induced by fishing: the role of adaptive phenotypic plasticity

Hidalgo

Olsen

Ohlberger

et al. 2014

Ecological Applications

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Mounting evidence now shows that fishing activity modifies both heritable life-history traits and ecological processes in harvested populations. However, ecological and evolutionary changes are intimately linked and can occur on the same time scale, and few studies have investigated their combined effect on fish population dynamics. Here, we contrast two population subunits of a harvested fish species in the Northeast Atlantic, the European hake (Merluccius merluccius), in the light of the emerging field of evolutionary demography, which considers the interacting processes between ecology and evolution. The two subunits experienced similar age/size truncation due to size-selective fishing, but displayed differences in key ecological processes (recruitment success) and phenotypic characteristics (maturation schedule). We investigate how temporal variation in maturation and recruitment success interactively shape the population dynamics of the two subunits. We document that the two subunits of European hake displayed different responses to fishing in maturation schedules, possibly because of the different level of adaptive phenotypic plasticity. Our results also suggest that high phenotypic plasticity can dampen the effects of fisheries-induced demographic truncation on population dynamics, whereas a population subunit characterized by low phenotypic plasticity may suffer from additive effects of ecological and life-history responses. Similar fishing pressure may thus trigger contrasting interactions between life history variation and ecological processes within the same population. The presented findings improve our understanding of how fishing impacts eco-evolutionary dynamics, which is a keystone for a more comprehensive management of harvested species.

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What can gene flow and recruitment dynamics tell us about connectivity between European hake stocks in the Eastern North Atlantic?

Cited by 24 publications

References 51 publications

Outlier SNP markers reveal fine‐scale genetic structuring across European hake populations (Merluccius merluccius)

Outlier SNP markers reveal fine‐scale genetic structuring across European hake populations (Merluccius merluccius)

Testing an otolith geochemistry approach to determine population structure and movements of European hake in the northeast Atlantic Ocean and Mediterranean Sea

Contrasting evolutionary demography induced by fishing: the role of adaptive phenotypic plasticity

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