Limits...
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.

Show MeSH

Related in: MedlinePlus

Frequency (percent) of the Pan I A allele in squares within areas.Areas defined by one degree longitude and one half degree latitude (dotted lines) are each split into four equal sized squares (not shown). Sampling stations within subareas are pooled for frequency estimation. Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Color coded divisions based on revised metacod definitions as detailed in paper [19], [61].
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2682699&req=5

pone-0005529-g002: Frequency (percent) of the Pan I A allele in squares within areas.Areas defined by one degree longitude and one half degree latitude (dotted lines) are each split into four equal sized squares (not shown). Sampling stations within subareas are pooled for frequency estimation. Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Color coded divisions based on revised metacod definitions as detailed in paper [19], [61].

Mentions: Spatial population differentiation exhibited by Pan I [19] is more fully explained by differences in depth among localities although depth and locality are confounded. We found large differences in allele frequencies among localities defined by pooling sampling stations in squares within areas (Figure 2; we pooled to increase sample size). Close inspection of the figure, however, shows that there can be large allele frequency differences among neighboring localities within divisions. These may be described as an inshore/offshore difference, however, depth is a more important explanatory variable. We found apparent spatial differentiation significant in all instances (P = 0.001 based on 1000 permutations in all instances. Table 2). Interestingly, the overall FST = 0.074 was considerably lower than found for Northeast-Southwest comparison [19]. Also the differentiation among sampling stations within divisions was higher than among divisions (Table 2).


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 (percent) of the Pan I A allele in squares within areas.Areas defined by one degree longitude and one half degree latitude (dotted lines) are each split into four equal sized squares (not shown). Sampling stations within subareas are pooled for frequency estimation. Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Color coded divisions based on revised metacod definitions as detailed in paper [19], [61].
© Copyright Policy
Related In: Results  -  Collection

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

pone-0005529-g002: Frequency (percent) of the Pan I A allele in squares within areas.Areas defined by one degree longitude and one half degree latitude (dotted lines) are each split into four equal sized squares (not shown). Sampling stations within subareas are pooled for frequency estimation. Atlantic cod in Icelandic Marine Research Institute spring spawning surveys in 2005, 2006, and 2007. Color coded divisions based on revised metacod definitions as detailed in paper [19], [61].
Mentions: Spatial population differentiation exhibited by Pan I [19] is more fully explained by differences in depth among localities although depth and locality are confounded. We found large differences in allele frequencies among localities defined by pooling sampling stations in squares within areas (Figure 2; we pooled to increase sample size). Close inspection of the figure, however, shows that there can be large allele frequency differences among neighboring localities within divisions. These may be described as an inshore/offshore difference, however, depth is a more important explanatory variable. We found apparent spatial differentiation significant in all instances (P = 0.001 based on 1000 permutations in all instances. Table 2). Interestingly, the overall FST = 0.074 was considerably lower than found for Northeast-Southwest comparison [19]. Also the differentiation among sampling stations within divisions was higher than among divisions (Table 2).

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