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Intense habitat-specific fisheries-induced selection at the molecular Pan I locus predicts imminent collapse of a major cod fishery.

Arnason E, Hernandez UB, Kristinsson K - PLoS ONE (2009)

Bottom Line: We hypothesize a potential collapse of the fishery.We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis.We speculate that immediate establishment of large no-take reserves may help avert collapse.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology, University of Iceland, Reykjavík, Iceland. einararn@hi.is

ABSTRACT
Predation is a powerful agent in the ecology and evolution of predator and prey. Prey may select multiple habitats whereby different genotypes prefer different habitats. If the predator is also habitat-specific the prey may evolve different habitat occupancy. Drastic changes can occur in the relation of the predator to the evolved prey. Fisheries exert powerful predation and can be a potent evolutionary force. Fisheries-induced selection can lead to phenotypic changes that influence the collapse and recovery of the fishery. However, heritability of the phenotypic traits involved and selection intensities are low suggesting that fisheries-induced evolution occurs at moderate rates at decadal time scales. The Pantophysin I (Pan I) locus in Atlantic cod (Gadus morhua), representing an ancient balanced polymorphism predating the split of cod and its sister species, is under an unusual mix of balancing and directional selection including current selective sweeps. Here we show that Pan I alleles are highly correlated with depth with a gradient of 0.44% allele frequency change per meter. AA fish are shallow-water and BB deep-water adapted in accordance with behavioral studies using data storage tags showing habitat selection by Pan I genotype. AB fish are somewhat intermediate although closer to AA. Furthermore, using a sampling design covering space and time we detect intense habitat-specific fisheries-induced selection against the shallow-water adapted fish with an average 8% allele frequency change per year within year class. Genotypic fitness estimates (0.08, 0.27, 1.00 of AA, AB, and BB respectively) predict rapid disappearance of shallow-water adapted fish. Ecological and evolutionary time scales, therefore, are congruent. We hypothesize a potential collapse of the fishery. We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis. We speculate that immediate establishment of large no-take reserves may help avert collapse.

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Related in: MedlinePlus

Frequency of Pan I A allele on mean depth (m) of sampling.Points (open circles ○) represent frequency at all sampling stations for Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Pluses+represent a generalized additive model (gam) smooth fit. Solid dots • represent a generalized linear regression (glm) of allele frequency on depth for depths less than 200 m; glm linear predictor η = 1.297−0.0195depth yields an allele frequency intercept of 78.5% and 34.2% at 100 m, a 44.3% change.
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pone-0005529-g001: Frequency of Pan I A allele on mean depth (m) of sampling.Points (open circles ○) represent frequency at all sampling stations for Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Pluses+represent a generalized additive model (gam) smooth fit. Solid dots • represent a generalized linear regression (glm) of allele frequency on depth for depths less than 200 m; glm linear predictor η = 1.297−0.0195depth yields an allele frequency intercept of 78.5% and 34.2% at 100 m, a 44.3% change.

Mentions: The relationship of allele frequency and depth was highly regular and significant (Figure 1, Table 1 and Figure S1; and see Table S1 for an overview of supplementary data) with frequency of the A allele decreasing rapidly to a depth of less than 200 m but staying relatively level in deeper waters. A linear regression equation of allele frequency of A on depth for depth less than 200 m was PA = 0.806−0.0044D (t = −14.6, P≪0.001) or a 0.44% drop in allele frequency per meter. A generalized linear model (glm) fit gave almost identical results (Figure 1).


Intense habitat-specific fisheries-induced selection at the molecular Pan I locus predicts imminent collapse of a major cod fishery.

Arnason E, Hernandez UB, Kristinsson K - PLoS ONE (2009)

Frequency of Pan I A allele on mean depth (m) of sampling.Points (open circles ○) represent frequency at all sampling stations for Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Pluses+represent a generalized additive model (gam) smooth fit. Solid dots • represent a generalized linear regression (glm) of allele frequency on depth for depths less than 200 m; glm linear predictor η = 1.297−0.0195depth yields an allele frequency intercept of 78.5% and 34.2% at 100 m, a 44.3% change.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2682699&req=5

pone-0005529-g001: Frequency of Pan I A allele on mean depth (m) of sampling.Points (open circles ○) represent frequency at all sampling stations for Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Pluses+represent a generalized additive model (gam) smooth fit. Solid dots • represent a generalized linear regression (glm) of allele frequency on depth for depths less than 200 m; glm linear predictor η = 1.297−0.0195depth yields an allele frequency intercept of 78.5% and 34.2% at 100 m, a 44.3% change.
Mentions: The relationship of allele frequency and depth was highly regular and significant (Figure 1, Table 1 and Figure S1; and see Table S1 for an overview of supplementary data) with frequency of the A allele decreasing rapidly to a depth of less than 200 m but staying relatively level in deeper waters. A linear regression equation of allele frequency of A on depth for depth less than 200 m was PA = 0.806−0.0044D (t = −14.6, P≪0.001) or a 0.44% drop in allele frequency per meter. A generalized linear model (glm) fit gave almost identical results (Figure 1).

Bottom Line: We hypothesize a potential collapse of the fishery.We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis.We speculate that immediate establishment of large no-take reserves may help avert collapse.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology, University of Iceland, Reykjavík, Iceland. einararn@hi.is

ABSTRACT
Predation is a powerful agent in the ecology and evolution of predator and prey. Prey may select multiple habitats whereby different genotypes prefer different habitats. If the predator is also habitat-specific the prey may evolve different habitat occupancy. Drastic changes can occur in the relation of the predator to the evolved prey. Fisheries exert powerful predation and can be a potent evolutionary force. Fisheries-induced selection can lead to phenotypic changes that influence the collapse and recovery of the fishery. However, heritability of the phenotypic traits involved and selection intensities are low suggesting that fisheries-induced evolution occurs at moderate rates at decadal time scales. The Pantophysin I (Pan I) locus in Atlantic cod (Gadus morhua), representing an ancient balanced polymorphism predating the split of cod and its sister species, is under an unusual mix of balancing and directional selection including current selective sweeps. Here we show that Pan I alleles are highly correlated with depth with a gradient of 0.44% allele frequency change per meter. AA fish are shallow-water and BB deep-water adapted in accordance with behavioral studies using data storage tags showing habitat selection by Pan I genotype. AB fish are somewhat intermediate although closer to AA. Furthermore, using a sampling design covering space and time we detect intense habitat-specific fisheries-induced selection against the shallow-water adapted fish with an average 8% allele frequency change per year within year class. Genotypic fitness estimates (0.08, 0.27, 1.00 of AA, AB, and BB respectively) predict rapid disappearance of shallow-water adapted fish. Ecological and evolutionary time scales, therefore, are congruent. We hypothesize a potential collapse of the fishery. We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis. We speculate that immediate establishment of large no-take reserves may help avert collapse.

Show MeSH
Related in: MedlinePlus