Arnaud Gaigher, CIBIO-InBIO, Marchange | November 08, 2019 – 15h30 | CIBIO-InBIO’s Auditorium, Campus de Vairão



Elucidating the mechanisms promoting and maintaining adaptive genetic diversity (i.e., variation at loci with a direct effect on fitness) is a central issue in evolutionary and conservation biology. Due to their key role in the adaptive immune response of vertebrates, genes of the major histocompatibility complex (MHC) are recurrently used as candidate markers to study the genetic basis of pathogen resistance and to depict how natural selection mediates adaptation to diseases. The extraordinarily high level of polymorphism as well as the complex evolutionary dynamics (including frequent gene duplication and loss, high rates of recombination and gene conversion) are the main hallmarks of the MHC system. Even though remarkable from an evolutionary perspective, such features entail certain practical disadvantages and can lead to biased estimations of MHC diversity and therefore impact downstream evolutionary ecology analyses. In this talk, I will present the step by step procedure that I used for characterizing the MHC system in the barn owl (Tyto alba), from genotyping thousands of samples to addressing key issues that have so far received little attention from the scientific community, and I will highlight underappreciated or unexpected problems in the context of MHC evolutionary analyses.


Arnaud Gaigher is an evolutionary biologist interested in understanding the genetic basis involved in the evolution of species and populations. After the completion of his Master at the Pierre and Marie Curie University (Paris), he moved to the University of Lausanne (Switzerland) to complete a PhD. During his PhD he focused on the evolutionary processes shaping adaptive immune diversity (mainly genes of the Major Histocompatibility Complex (MHC)) in natural populations of barn owl (Tyto alba). He has addressed issues covering a broad range of topics such as the improvement of MHC genotyping, the molecular evolution of MHC genes, the strength of the link between MHC diversity and individual fitness-related traits, the geographical structure of MHC diversity and MHC-mediated sexual selection. Stemming from a curious and cooperative nature, Arnaud has been involved in several different projects using different model species (lampreys, butterflies…) and various genetic tools (microsatellites, SNP, genomes, and adaptive markers (MHC or MC1R)) all in a context related to phylogeography, phylogenetics, population genetics or molecular evolution.





[Host: Ana Veríssimo, Marine Ecology, Diversity and Change]
Image credits: Arnaud Gaigher