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Open Access Highly Accessed Methodology article

Evolution of MHC class I genes in the endangered loggerhead sea turtle (Caretta caretta) revealed by 454 amplicon sequencing

Victor A Stiebens1, Sonia E Merino2, Frédéric J J Chain3 and Christophe Eizaguirre13*

Author Affiliations

1 Department of Evolutionary Ecology of Marine Fishes, GEOMAR|Helmholtz Center for Ocean Research, Kiel, 24105, Germany

2 National Institute for Development and Fishery (INDP), Mindelo, Cape Verde

3 Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Ploen, 24306, Germany

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BMC Evolutionary Biology 2013, 13:95  doi:10.1186/1471-2148-13-95

Published: 30 April 2013

Abstract

Background

In evolutionary and conservation biology, parasitism is often highlighted as a major selective pressure. To fight against parasites and pathogens, genetic diversity of the immune genes of the major histocompatibility complex (MHC) are particularly important. However, the extensive degree of polymorphism observed in these genes makes it difficult to conduct thorough population screenings.

Methods

We utilized a genotyping protocol that uses 454 amplicon sequencing to characterize the MHC class I in the endangered loggerhead sea turtle (Caretta caretta) and to investigate their evolution at multiple relevant levels of organization.

Results

MHC class I genes revealed signatures of trans-species polymorphism across several reptile species. In the studied loggerhead turtle individuals, it results in the maintenance of two ancient allelic lineages. We also found that individuals carrying an intermediate number of MHC class I alleles are larger than those with either a low or high number of alleles.

Conclusions

Multiple modes of evolution seem to maintain MHC diversity in the loggerhead turtles, with relatively high polymorphism for an endangered species.

Keywords:
Major histocompatibility complex; Loggerhead sea turtle; Trans-species polymorphism; Reptiles; Intermediate diversity