Katja Helena Rönkä, Fabrice Eroukhmanoff, Jonna Kulmuni, Pierre Nouhaud, Rose Thorogood

Brood parasite-host interactions are among the most easily observable and amenable natural laboratories of antagonistic coevolution, and as such have intrigued evolutionary biologists for decades. It is therefore surprising they have not been at the forefront of genomic studies on evolutionary adaptation. Here we review state-of-the-art molecular methods in studying avian brood parasitism, a model system in behavioural ecology. We highlight outstanding questions to bring examples of how genomic tools are not merely about ‘finding a gene for behaviour’, but can be used to study the causes and mechanisms of (co)evolutionary adaptation. In doing so, we promote behavioural and molecular ecologists to integrate Tinbergen’s questions into a collaborative, coherent science aiming to solve the mysteries of nature and apply current methodology into other model systems in behavioural ecology.