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Defining conservation units in a stocking-induced genetic melting pot: unraveling native and multiple exotic genetic imprints of recent and historical secondary contact in Adriatic grayling.

Meraner A, Cornetti L, Gandolfi A - Ecol Evol (2014)

Bottom Line: Within the Adige River system, a contact zone of western Adriatic and eastern Danubian populations was detected, with ABC analyses suggesting a historical anthropogenic origin of eastern Adige populations, most likely founded by medieval translocations.Substantial river-specific population substructure within the Adriatic grayling Evolutionary Significant Unit points to the definition of different conservation units.We finally propose a catalog of management measures, including the legal prohibition of stocking exotic grayling and the use of molecular markers in supportive- and captive-breeding programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach Via E. Mach 1, 38010, San Michele all'Adige, TN, Italy.

ABSTRACT
The definition of conservation units is crucial for the sustainable management of endangered species, though particularly challenging when recent and past anthropogenic and natural gene flow might have played a role. The conservation of the European grayling, Thymallus thymallus, is particularly complex in its southern distribution area, where the Adriatic evolutionary lineage is endangered by a long history of anthropogenic disturbance, intensive stocking and potentially widespread genetic introgression. We provide mtDNA sequence and microsatellite data of 683 grayling from 30 sites of Adriatic as well as Danubian and Atlantic origin. We apply Bayesian clustering and Approximate Bayesian Computation (ABC) to detect microgeographic population structure and to infer the demographic history of the Adriatic populations, to define appropriate conservation units. Varying frequencies of indigenous genetic signatures of the Adriatic grayling were revealed, spanning from marginal genetic introgression to the collapse of native gene pools. Genetic introgression involved multiple exotic source populations of Danubian and Atlantic origin, thus evidencing the negative impact of few decades of stocking. Within the Adige River system, a contact zone of western Adriatic and eastern Danubian populations was detected, with ABC analyses suggesting a historical anthropogenic origin of eastern Adige populations, most likely founded by medieval translocations. Substantial river-specific population substructure within the Adriatic grayling Evolutionary Significant Unit points to the definition of different conservation units. We finally propose a catalog of management measures, including the legal prohibition of stocking exotic grayling and the use of molecular markers in supportive- and captive-breeding programs.

No MeSH data available.


Related in: MedlinePlus

Graphic representation of the hierarchical ABC analysis, with three scenarios tested for each of the two steps. Relative posterior probabilities, obtained through a logistic regression computed every 10% of the number of 30,000 simulated data closest to the observed data, are presented for scenarios A, B, and C (top right) and for Arecent, Ahistorical, and Aancient (bottom right). Posterior probability, computed on 30,000 simulated data closest to the observed data, and 95% confidence interval are shown for each scenario. Populations codes: SES = Sesia; UNS = unsampled population; ADI = Adige; ISA = Isarco; DRA = Drava. rXtoY (rate of admixture) represents the contribution of a population X to the origin of a new admixed population Y, ranging from 0 to 1.
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fig04: Graphic representation of the hierarchical ABC analysis, with three scenarios tested for each of the two steps. Relative posterior probabilities, obtained through a logistic regression computed every 10% of the number of 30,000 simulated data closest to the observed data, are presented for scenarios A, B, and C (top right) and for Arecent, Ahistorical, and Aancient (bottom right). Posterior probability, computed on 30,000 simulated data closest to the observed data, and 95% confidence interval are shown for each scenario. Populations codes: SES = Sesia; UNS = unsampled population; ADI = Adige; ISA = Isarco; DRA = Drava. rXtoY (rate of admixture) represents the contribution of a population X to the origin of a new admixed population Y, ranging from 0 to 1.

Mentions: Approximate Bayesian Computation (ABC; Beaumont et al. 2002) is a family of statistical techniques to perform parameter estimation and model selection, increasingly used in ecology and evolution to make inferences about complex evolutionary scenarios, bypassing direct estimates of likelihood function and adopting comparison between observed and simulated summary statistics (Cornuet et al. 2010). To depict the most likely colonization scenario for eastern Adige and the potential genetic contribution to western Adige populations through gene flow, we applied ABC as implemented in the DIYABC v.1.0.4 package (Cornuet et al. 2008, 2010). Firstly, we defined four meta-populations: three from Adriatic and one from Danubian water courses. The data from 12 microsatellite markers following a generalized stepwise mutation model were retained (TAR100, TAR104 and TAR110 were excluded because containing imperfect, i.e., non-strictly tetranucleotidic, repeats). As signals of genetic introgression from recently stocked specimens had been detected in all sampling sites by the STRUCTURE analysis, for each cluster, we selected individuals with q-values >0.90 only, and defined samples SES (Po basin, Adriatic, N = 20) from SES_1, ADI (western Adige basin, Adriatic, N = 40), by pooling individuals from ADI_1, ADI_2, ADI_3, ADI_4, ADI_5, and ADI_6, ISA (eastern Adige basin, Adriatic, N = 39), by pooling individuals from RIE_1, RIE_2, ISA_1, and AUR_1, and DRA (Drava basin, Danubian, N = 40) by pooling individuals from DRA_1, DRA_2 and DRA_3 (Fig. 4).


Defining conservation units in a stocking-induced genetic melting pot: unraveling native and multiple exotic genetic imprints of recent and historical secondary contact in Adriatic grayling.

Meraner A, Cornetti L, Gandolfi A - Ecol Evol (2014)

Graphic representation of the hierarchical ABC analysis, with three scenarios tested for each of the two steps. Relative posterior probabilities, obtained through a logistic regression computed every 10% of the number of 30,000 simulated data closest to the observed data, are presented for scenarios A, B, and C (top right) and for Arecent, Ahistorical, and Aancient (bottom right). Posterior probability, computed on 30,000 simulated data closest to the observed data, and 95% confidence interval are shown for each scenario. Populations codes: SES = Sesia; UNS = unsampled population; ADI = Adige; ISA = Isarco; DRA = Drava. rXtoY (rate of admixture) represents the contribution of a population X to the origin of a new admixed population Y, ranging from 0 to 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4020691&req=5

fig04: Graphic representation of the hierarchical ABC analysis, with three scenarios tested for each of the two steps. Relative posterior probabilities, obtained through a logistic regression computed every 10% of the number of 30,000 simulated data closest to the observed data, are presented for scenarios A, B, and C (top right) and for Arecent, Ahistorical, and Aancient (bottom right). Posterior probability, computed on 30,000 simulated data closest to the observed data, and 95% confidence interval are shown for each scenario. Populations codes: SES = Sesia; UNS = unsampled population; ADI = Adige; ISA = Isarco; DRA = Drava. rXtoY (rate of admixture) represents the contribution of a population X to the origin of a new admixed population Y, ranging from 0 to 1.
Mentions: Approximate Bayesian Computation (ABC; Beaumont et al. 2002) is a family of statistical techniques to perform parameter estimation and model selection, increasingly used in ecology and evolution to make inferences about complex evolutionary scenarios, bypassing direct estimates of likelihood function and adopting comparison between observed and simulated summary statistics (Cornuet et al. 2010). To depict the most likely colonization scenario for eastern Adige and the potential genetic contribution to western Adige populations through gene flow, we applied ABC as implemented in the DIYABC v.1.0.4 package (Cornuet et al. 2008, 2010). Firstly, we defined four meta-populations: three from Adriatic and one from Danubian water courses. The data from 12 microsatellite markers following a generalized stepwise mutation model were retained (TAR100, TAR104 and TAR110 were excluded because containing imperfect, i.e., non-strictly tetranucleotidic, repeats). As signals of genetic introgression from recently stocked specimens had been detected in all sampling sites by the STRUCTURE analysis, for each cluster, we selected individuals with q-values >0.90 only, and defined samples SES (Po basin, Adriatic, N = 20) from SES_1, ADI (western Adige basin, Adriatic, N = 40), by pooling individuals from ADI_1, ADI_2, ADI_3, ADI_4, ADI_5, and ADI_6, ISA (eastern Adige basin, Adriatic, N = 39), by pooling individuals from RIE_1, RIE_2, ISA_1, and AUR_1, and DRA (Drava basin, Danubian, N = 40) by pooling individuals from DRA_1, DRA_2 and DRA_3 (Fig. 4).

Bottom Line: Within the Adige River system, a contact zone of western Adriatic and eastern Danubian populations was detected, with ABC analyses suggesting a historical anthropogenic origin of eastern Adige populations, most likely founded by medieval translocations.Substantial river-specific population substructure within the Adriatic grayling Evolutionary Significant Unit points to the definition of different conservation units.We finally propose a catalog of management measures, including the legal prohibition of stocking exotic grayling and the use of molecular markers in supportive- and captive-breeding programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach Via E. Mach 1, 38010, San Michele all'Adige, TN, Italy.

ABSTRACT
The definition of conservation units is crucial for the sustainable management of endangered species, though particularly challenging when recent and past anthropogenic and natural gene flow might have played a role. The conservation of the European grayling, Thymallus thymallus, is particularly complex in its southern distribution area, where the Adriatic evolutionary lineage is endangered by a long history of anthropogenic disturbance, intensive stocking and potentially widespread genetic introgression. We provide mtDNA sequence and microsatellite data of 683 grayling from 30 sites of Adriatic as well as Danubian and Atlantic origin. We apply Bayesian clustering and Approximate Bayesian Computation (ABC) to detect microgeographic population structure and to infer the demographic history of the Adriatic populations, to define appropriate conservation units. Varying frequencies of indigenous genetic signatures of the Adriatic grayling were revealed, spanning from marginal genetic introgression to the collapse of native gene pools. Genetic introgression involved multiple exotic source populations of Danubian and Atlantic origin, thus evidencing the negative impact of few decades of stocking. Within the Adige River system, a contact zone of western Adriatic and eastern Danubian populations was detected, with ABC analyses suggesting a historical anthropogenic origin of eastern Adige populations, most likely founded by medieval translocations. Substantial river-specific population substructure within the Adriatic grayling Evolutionary Significant Unit points to the definition of different conservation units. We finally propose a catalog of management measures, including the legal prohibition of stocking exotic grayling and the use of molecular markers in supportive- and captive-breeding programs.

No MeSH data available.


Related in: MedlinePlus