Beyond genes-for-behaviour: the potential for genomics to resolve questions in avian brood parasitism

Abstract

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.

Phenotypic correlates between clock genes and phenology among populations of Diederik cuckoo, Chrysococcyx caprius

“…For example, the Australian Horsfield's bronze cuckoo, Chrysococcyx basalis [Horsfield, 1821], parasitises resident populations of Superb fairy‐wren (Langmore et al., 2008 ), Malurus cyaneus [Ellis, 1782], while the Common cuckoo, Cuculus canorus [Linnaeus, 1758], parasitises several resident as well as short and long distance migrants (Saino et al., 2009 ). Due to this ‘evolutionary arms race’ most cuckoos need to be highly synchronised to their host species and follow a pattern of co‐evolution (Rönkä et al., 2022 ) with their hosts that results in host‐specific races; which differ in several phenotypic and behavioural attributes without constituting definitive subspecies but are rather more similar to ecotypes (Langmore et al., 2008 ; Reed, 1968 ; Skead, 1952 ; Soler & Soler, 2000 ). These races exhibit phenotypical variation that includes differences in egg characteristics such as coloration (Caves et al., 2015 ; Reed, 1968 ) and shell density (Spottiswoode, 2010 ), behavioural adaptations, such as the mimicking of different host sounds and behaviour (Langmore et al., 2008 ; Reed, 1968 ), persistent shared ectoparasite profiles (Lindholm et al., 1998 ), and high synchronicity in timing of migration and breeding (Douglas et al., 2010 ).…”