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  • 1
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    Springer
    In:  Conservation Genetics Resources, 7 (4). pp. 859-870.
    Publikationsdatum: 2019-01-21
    Beschreibung: Many exploited fish species are threatened with collapse and the European eel is no exception. Its abundance has declined dramatically and various reasons account for this, among them the introduction of the invasive swim bladder nematode Anguillicola crassus. For developing an adequate immune response against this parasite, variation at the genes of the major histocompatibility complex (MHC), a key component of the adaptive immune system, might be essential and assessing their diversity might provide critical information for improving conservation strategies. Here, we characterized the MHC class II of the European eel. We provide evidence for relatively high diversity at both MHC IIA and MHC IIB, which contrasts with findings for other endangered species. Furthermore, both genes show signs of site-specific positive selection. The absence of overall positive selection at MHC IIB might, however, suggests that demographic shifts have negatively impacted that gene, thereby possibly reducing the adaptive potential of the European eel.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2019-02-01
    Beschreibung: The recent increased integration of evolutionary theory into conservation programs has greatly improved our ability to protect endangered species. A common application of such theory links population dynamics and indices of genetic diversity, usually estimated from neutrally evolving markers. However, some studies have suggested that highly polymorphic adaptive genes, such as the immune genes of the Major Histocompatibility Complex (MHC), might be more sensitive to fluctuations in population dynamics. As such, the combination of neutrally- and adaptively-evolving genes may be informative in populations where reductions in abundance have been documented. The European eel (Anguilla anguilla) underwent a drastic and well-reported decline in abundance in the late 20th century and still displays low recruitment. Here we compared genetic diversity indices estimated from neutral (mitochondrial DNA and microsatellites) and adaptive markers (MHC) between two distinct generations of European eels. Our results revealed a clear discrepancy between signatures obtained for each class of markers. Although mtDNA and microsatellites showed no changes in diversity between the older and the younger generations, MHC diversity revealed a contemporary drop followed by a recent increase. Our results suggest ongoing gain of MHC genetic diversity resulting from the interplay between drift and selection and ultimately increasing the adaptive potential of the species.
    Materialart: Article , PeerReviewed
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    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2020-02-06
    Beschreibung: BACKGROUND: The Major Histocompatibility Complex (MHC) is a key component of the adaptive immune system of all vertebrates and consists of the most polymorphic genes known to date. Due to this complexity, however, MHC remains to be characterized in many species including any Neotropical cichlid fish. Neotropical crater lake cichlids are ideal models to study evolutionary processes as they display one of the most convincing examples of sympatric and repeated parallel radiation events within and among isolated crater lakes. RESULTS: Here, we characterized the genes of MHC class IIB chain of the Midas cichlid species complex (Amphilophus cf. citrinellus) including fish from five lakes in Nicaragua. We designed 19 new specific primers anchored in a stepwise fashion in order to detect all alleles present. We obtained 866 genomic DNA (gDNA) sequences from thirteen individuals and 756 additional sequences from complementary DNA (cDNA) of seven of those individuals. We identified 69 distinct alleles with up to 25 alleles per individual. We also found considerable intron length variation and mismatches of alleles detected in cDNA and gDNA suggesting that some loci have undergone pseudogenization. Lastly, we created a model of protein structure homology for each allele and identified their key structural components. CONCLUSIONS: Overall, the Midas cichlid has one of the most diverse repertoires of MHC class IIB genes known, which could serve as a powerful tool to elucidate the process of divergent radiations, colonization and speciation in sympatry
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
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    In:  (Master thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 65 pp
    Publikationsdatum: 2013-11-19
    Schlagwort(e): Course of study: MSc Biological Oceanography
    Materialart: Thesis , NonPeerReviewed
    Format: text
    Standort Signatur Einschränkungen Verfügbarkeit
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