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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

Boxplots of gill raker count (GRC) distributions in reintroduced populations across the North Sea houting (NSH) and Baltic houting (BH) ranges, and in the BH_PEE and European whitefish (EW) source populations. For the source NSH_VID, no gill rakers were available.
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fig02: Boxplots of gill raker count (GRC) distributions in reintroduced populations across the North Sea houting (NSH) and Baltic houting (BH) ranges, and in the BH_PEE and European whitefish (EW) source populations. For the source NSH_VID, no gill rakers were available.

Mentions: When comparing the source populations, the indigenous BH population BH_PEE was characterized by slightly but significantly lower GRC than indigenous NSH populations (Table S2; T46 = 2.16, P = 0.036). Secondly, GRC of indigenous BH and NSH populations were both significantly lower than EW GRC (BH: Table2; NSH versus EW_BOR: T4 = −3.05, P = 0.038; NSH versus EW_POE: T22 = −14.95, P < 0.001). The situation among reintroduced populations differed between the distribution ranges (Fig.2). For NSH, the GRCs in the NSH_TRE and NSH_ELB were comparable with literature values for indigenous NSH, albeit with wider trait variation (Table2 and S2). In contrast, strong interpopulation differences characterized the BH distribution range. While GRCs in the BH_TRA were comparable with those in its putative BH_PEE source (Tukey's post hoc test; t = 0.56, P = 0.99), the BH_SCH was comparable with the NSH populations NSH_TRE (t = −1.07, P = 0.99) and NSH_ELB (t = −0.81, P = 0.99), and the BH_NOK as well as BH_LAC with the EW population EW_BOR (all pairwise comparisons summarized in Table2). Fish size (ancova, F1,243 = 1.63, P = 0.204) and sex (F2, 243 = 1.41, P = 0.220) were not associated with GRC.


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)

Boxplots of gill raker count (GRC) distributions in reintroduced populations across the North Sea houting (NSH) and Baltic houting (BH) ranges, and in the BH_PEE and European whitefish (EW) source populations. For the source NSH_VID, no gill rakers were available.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig02: Boxplots of gill raker count (GRC) distributions in reintroduced populations across the North Sea houting (NSH) and Baltic houting (BH) ranges, and in the BH_PEE and European whitefish (EW) source populations. For the source NSH_VID, no gill rakers were available.
Mentions: When comparing the source populations, the indigenous BH population BH_PEE was characterized by slightly but significantly lower GRC than indigenous NSH populations (Table S2; T46 = 2.16, P = 0.036). Secondly, GRC of indigenous BH and NSH populations were both significantly lower than EW GRC (BH: Table2; NSH versus EW_BOR: T4 = −3.05, P = 0.038; NSH versus EW_POE: T22 = −14.95, P < 0.001). The situation among reintroduced populations differed between the distribution ranges (Fig.2). For NSH, the GRCs in the NSH_TRE and NSH_ELB were comparable with literature values for indigenous NSH, albeit with wider trait variation (Table2 and S2). In contrast, strong interpopulation differences characterized the BH distribution range. While GRCs in the BH_TRA were comparable with those in its putative BH_PEE source (Tukey's post hoc test; t = 0.56, P = 0.99), the BH_SCH was comparable with the NSH populations NSH_TRE (t = −1.07, P = 0.99) and NSH_ELB (t = −0.81, P = 0.99), and the BH_NOK as well as BH_LAC with the EW population EW_BOR (all pairwise comparisons summarized in Table2). Fish size (ancova, F1,243 = 1.63, P = 0.204) and sex (F2, 243 = 1.41, P = 0.220) were not associated with GRC.

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