Fungus, frogs and MHC: the role of sexual selection in the evolution of disease resistance

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Sexual selection (SS) is a strong evolutionary force that can promote or inhibit adaptation to environmental challenges. When populations face novel pathogens, SS can influence their persistence by impacting the spread of resistance alleles; specifically, the Major Histocompatibility Complex (MHC) that encodes proteins that recognize pathogens and activate the acquired immune system. Many vertebrates preferentially mate with partners carrying beneficial MHC alleles, conferring higher resistance to the offspring. Here, I propose to study the role of SS in the evolutionary dynamics of amphibian resistance to chytridiomycosis (chytrid), an emerging infectious disease that is causing population declines and extinctions worldwide. I will use poison frogs, a species-rich group in which the strength of SS differs between species, and that is experiencing dramatic population declines. I will test whether mate choice is influenced by i) MHC and ii) infection status ofboth partners. Subsequently, I will use comparative analysis and field surveys to iii) evaluate the association between the strength of SS and species’ susceptibility to chytrid, testing the prediction that species with SS selection are more resistant.This project will not only contribute to our general understanding of the role of SS in adaptation and disease dynamics, but also present the first experimental analysis of MHC-based mate choice in amphibians. Results will be highly relevant for amphibian conservation, by identifying a major factor underlying species differences in chytrid resistance, which will help to set conservation priorities. I have worked with chytrid throughout my academic career; this project allows me to focus on the host, which has been the target of fewer studies and is in dire need of conservation. The project will be conducted at the University of Groningen under the supervision of Dr. Maan, an expert on SS and poison frogs; field work will be carried out in Brazil.