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Anthropogenic hybridization between endangered migratory and commercially harvested stationary whitefish taxa (Coregonus spp.).

Dierking J, Phelps L, Præbel K, Ramm G, Prigge E, Borcherding J, Brunke M, Eizaguirre C - Evol Appl (2014)

Bottom Line: We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW).The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range.Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.

View Article: PubMed Central - PubMed

Affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.

ABSTRACT
Natural hybridization plays a key role in the process of speciation. However, anthropogenic (human induced) hybridization of historically isolated taxa raises conservation issues. Due to weak barriers to gene flow and the presence of endangered taxa, the whitefish species complex is an excellent study system to investigate the consequences of hybridization in conservation. We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW). To evaluate the genetic integrity of each taxon, source and reintroduced populations of NSH and BH, and EW populations were characterized based on two mitochondrial and 17 microsatellite loci. Additionally, we investigated gill raker counts as an adaptive phenotypic trait. Even though clear genetic and phenotypic differentiation confirmed the houtings as separate evolutionarily significant units, admixture analyses revealed an extensive hybrid zone. Hybridizations were introgressive, positively correlated with genetic diversity, and were reflected in the gill raker counts. The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range. Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.

No MeSH data available.


Related in: MedlinePlus

Bayesian clustering of all individuals obtained with STRUCTURE 2.3, assuming the presence of three clusters (K = 3). Each vertical bar represents one individual, and the three colors denote the inferred proportional genotypic contributions of each cluster. Potential source populations for reintroductions to the historic ranges are put on the left and all reintroduced populations on the right side of the figure. According to official information, NSH_VID was used for reintroductions to the historic NSH range and BH_PEE to the historic BH range.
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fig05: Bayesian clustering of all individuals obtained with STRUCTURE 2.3, assuming the presence of three clusters (K = 3). Each vertical bar represents one individual, and the three colors denote the inferred proportional genotypic contributions of each cluster. Potential source populations for reintroductions to the historic ranges are put on the left and all reintroduced populations on the right side of the figure. According to official information, NSH_VID was used for reintroductions to the historic NSH range and BH_PEE to the historic BH range.

Mentions: Overall, the STRUCTURE analysis revealed K = 3 as most likely number of clusters represented by the sampled individuals after the exclusion of vendace (Fig. S3). The analysis confirmed the dominance of native NSH genotypes across the historic NSH range, but also revealed the additional influence of both EW and BH genotypes in reintroduced populations (Fig.5). No temporal differences in the contribution of NSH genotype in the NSH_TRE were apparent over the period 2004–2012 (anova; F4,138 = 0.78, P = 0.538), suggesting that admixture occurred before 2004 or elsewhere than in the Treene River. Within the NSH_RHI system, no spatial structuring was detected (F2,88 = 0.34, P = 0.711).


Anthropogenic hybridization between endangered migratory and commercially harvested stationary whitefish taxa (Coregonus spp.).

Dierking J, Phelps L, Præbel K, Ramm G, Prigge E, Borcherding J, Brunke M, Eizaguirre C - Evol Appl (2014)

Bayesian clustering of all individuals obtained with STRUCTURE 2.3, assuming the presence of three clusters (K = 3). Each vertical bar represents one individual, and the three colors denote the inferred proportional genotypic contributions of each cluster. Potential source populations for reintroductions to the historic ranges are put on the left and all reintroduced populations on the right side of the figure. According to official information, NSH_VID was used for reintroductions to the historic NSH range and BH_PEE to the historic BH range.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231596&req=5

fig05: Bayesian clustering of all individuals obtained with STRUCTURE 2.3, assuming the presence of three clusters (K = 3). Each vertical bar represents one individual, and the three colors denote the inferred proportional genotypic contributions of each cluster. Potential source populations for reintroductions to the historic ranges are put on the left and all reintroduced populations on the right side of the figure. According to official information, NSH_VID was used for reintroductions to the historic NSH range and BH_PEE to the historic BH range.
Mentions: Overall, the STRUCTURE analysis revealed K = 3 as most likely number of clusters represented by the sampled individuals after the exclusion of vendace (Fig. S3). The analysis confirmed the dominance of native NSH genotypes across the historic NSH range, but also revealed the additional influence of both EW and BH genotypes in reintroduced populations (Fig.5). No temporal differences in the contribution of NSH genotype in the NSH_TRE were apparent over the period 2004–2012 (anova; F4,138 = 0.78, P = 0.538), suggesting that admixture occurred before 2004 or elsewhere than in the Treene River. Within the NSH_RHI system, no spatial structuring was detected (F2,88 = 0.34, P = 0.711).

Bottom Line: We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW).The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range.Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.

View Article: PubMed Central - PubMed

Affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.

ABSTRACT
Natural hybridization plays a key role in the process of speciation. However, anthropogenic (human induced) hybridization of historically isolated taxa raises conservation issues. Due to weak barriers to gene flow and the presence of endangered taxa, the whitefish species complex is an excellent study system to investigate the consequences of hybridization in conservation. We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW). To evaluate the genetic integrity of each taxon, source and reintroduced populations of NSH and BH, and EW populations were characterized based on two mitochondrial and 17 microsatellite loci. Additionally, we investigated gill raker counts as an adaptive phenotypic trait. Even though clear genetic and phenotypic differentiation confirmed the houtings as separate evolutionarily significant units, admixture analyses revealed an extensive hybrid zone. Hybridizations were introgressive, positively correlated with genetic diversity, and were reflected in the gill raker counts. The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range. Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.

No MeSH data available.


Related in: MedlinePlus