Major Histocompatibility Complex Polymorphism in Reptile Conservation

—Genes of the major histocompatibility complex (MHC) are closely related to disease resistance and immune response in vertebrates. Although many groups are well represented in the MHC literature, less attention has been given to reptiles. Here we summarize reptile MHC studies, review published accounts investigating links between MHC polymorphism, parasite resistance, and mate choice, evaluate current limitations, and discuss prospects of new technologies for future research. MHC polymorphism appears to be extensive in reptile populations, and current evidence suggests MHC polymorphism may influence parasite resistance and mate choice as in other vertebrates. Prior research strategies have been limited by the type of molecular markers available, the nature of the sequences being amplified, the number of individuals and populations analyzed, the immunology and biology of the host-parasite relationship, and the conditions under which subjects are studied. Finally, reptiles offer special challenges: as ectotherms their susceptibility to pathogens may change dramatically depending on the time of year due to seasonal variations in their immunity. Including a temperature and/or seasonal variable may thus provide new insights into the genetic mechanisms of disease resistance. New technologies and techniques should help to alleviate problems of MHC gene characterization and multi-locus amplification associated with past research and contribute to our understanding of MHC polymorphism in reptile conservation.