Lineage-specific histories rather than shared drivers shape olfactory evolution in New World monkeys
Year: 2026
Type: preprint
Abstract: Variation in primate olfactory receptor gene repertoires has been linked to shared ecological and sensory drivers, including diet, diurnality, and colour vision. Yet within anthropoids, each link rests on a single lineage, leaving unclear whether this variation reflects a shared response to these drivers or lineage-specific histories. Here, we combine genomic data from 80 New World monkey species with CT-based olfactory anatomy and ecological data to investigate the evolutionary processes underlying repertoire variation. Ecological and sensory variables explain little of this variation; even routinely trichromatic, leaf-eating howler monkeys have repertoires of unremarkable size. Instead, convergent reductions in repertoire size arose through distinct genomic routes: extensive gene inactivation in titi monkeys and large structural deletions in squirrel monkeys. Owl monkeys, the only anthropoids that reverted to nocturnality, retained rather than expanded a large ancestral repertoire shared with diurnal capuchins, and instead enlarged their olfactory bulb. Repertoire size covaries with olfactory bulb volume across the radiation, but only partially within lineages: squirrel monkeys show the converse, losing receptors without a matching bulb reduction. Thus, olfactory evolution in New World monkeys reflects historical contingency rather than a shared response, with convergent changes in repertoire size and partial decoupling of genomic and anatomical evolution.
Language: English
Subfield: Sensory Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7225378722