Summary
A bioRxiv preprint reports that canary breeds selected for song differ from other breeds in neural development, song-related brain regions and auditory sensitivity. Genome-wide findings point to many genes contributing to song divergence, including an ADGRV1 variant associated with singing and hearing traits.
Artificial selection for song has been accompanied by changes in canaries’ hearing and song-related brain systems, according to a bioRxiv preprint. Comparing song breeds with canaries selected for plumage or body form, the researchers report increased neural progenitor proliferation in song breeds, alongside breed-specific differences in neuronal recruitment, sensorimotor brain-region volume and auditory sensitivity.
Domestic canaries have been bred for different traits for roughly four centuries. Their song breeds provide a way to study how vocal behaviour can diverge within a species. The preprint’s findings suggest that this divergence involves more than the motor system that produces song: sensory processing, including hearing, may also be shaped during selection.
Genetic and neural differences span several systems
Genome-wide analyses reported in the study point to a polygenic architecture for song divergence. This means the differences are associated with many genetic changes rather than a single variant. The implicated genes were enriched for roles in transcriptional regulation—the control of gene activity—and synaptic transmission, the communication process between nerve cells.
The researchers also identified a coding variant in ADGRV1 associated in canaries with low-frequency singing and elevated auditory thresholds. An auditory threshold is the sound level at which a sound can be detected; a higher threshold indicates that louder sound is needed for detection. ADGRV1 is also the gene mutated in human Usher syndrome type 2C.
To investigate a possible sensory mechanism, the team disrupted adgrv1 in zebrafish and observed altered dynamics in hair cells, sensory cells involved in detecting sound. This result connects the gene to a peripheral sensory process, while the canary finding is an association between the variant and singing and hearing traits.
Why hearing may matter for learned song
Songbirds learn vocalizations through social interaction, and auditory feedback helps them acquire and maintain song. The study’s combination of auditory, neural and genetic findings therefore points to a broader route by which vocal behaviour can diversify: selection may act on the sensory systems that receive sound as well as the neural circuits that guide learned song and its production.
The work is a bioRxiv preprint. Its findings concern canaries and a zebrafish gene-disruption experiment; the reported results are not a human study.