Association between louse abundance and MHC II supertypes in Galápagos mockingbirds

The thesis is based on the following publication:

I. Vlček J., Štefka J. (2020) Association between louse abundance and MHC II supertypes in Galápagos mockingbirds. Parasitology Research. 119, 1597–1605 (IF=2.3). Vlček Jakub and ŠJ conceptualise ideas behind the study. VJ carried out all analyses and wrote the manuscript with help of ŠJ. VJ contribution 75%

Link to the publication: https://phthiraptera.myspecies.info/node/94934 and publisher website: https://link.springer.com/article/10.1007/s00436-020-06617-3

Abstract:

Major histocompatibility complex class II (MHC II) is an essential molecule triggering the adaptive immune response by the presentation of pathogens to helper T cells. The association between individual MHC II variants and various parasites has become a frequent finding in studies of vertebrate populations. However, although bird ectoparasites have a significant effect on their host’s fitness, and the host’s immune system can regulate ectoparasitic infections, no study has yet investigated the
association between MHC II polymorphism and ectoparasite infection in the populations of free-living birds. Here we test whether an association exists between the abundance of a chewing louse (Myrsidea nesomimi) and MHC II polymorphism of its hosts, the Galápagos mockingbirds (Mimus). We have found that the presence of two MHC II supertypes (functionally differentiated clusters) was significantly associated with louse abundance. This pattern supports the theory that a co-evolutionary interaction stands behind a maintenance of MHC polymorphism. Moreover, we have found a positive correlation between louse abundance and heterophil/lymphocyte ratio (an indicator of immunological stress), that serves as an additional piece of evidence that ectoparasite burden is affected by immunological state in Galápagos mockingbirds.