Decoding the Scent of Life: A Study of Vertebrate Body Odours
Vertebrate body odours are complex blends of volatile compounds that animals use to communicate with each other, find food, and avoid predators. However, we still know relatively little about the composition of these odours and how they vary across species. In a new study, researchers at Princeton’s McBride Lab led by Jessica L Zung have conducted the first large-scale survey of vertebrate body odours, analyzing the scents of 64 species from 29 families and 13 orders.
They found that vertebrate body odours are typically made up of a relatively small number of common compounds, and that there is a great deal of overlap in the composition of odours from different species. This suggests that blood-feeding arthropods, such as mosquitoes, may have to rely on combinatorial coding strategies to discriminate between different hosts.
The researchers also found that vertebrate body odours carry little phylogenetic information, meaning that closely related species do not necessarily have similar odours. However, there is a high degree of consistency in the odour of individuals within a species. This suggests that body odour may play a role in individual recognition and social interactions.
They went further to make specific predictions about how mosquitoes have evolved to encode host odour. Their predictions align with known features of mosquito olfactory systems, suggesting that mosquitoes may use a combination of combinatorial coding and labelled lines to detect and discriminate between different hosts.
The study’s findings have a number of implications for our understanding of olfactory coding and evolution. For example, it proposes that the finding that vertebrate body odours are typically made up of a relatively small number of common compounds suggests that animals may have evolved to focus on detecting the presence or absence of specific combinations of compounds, rather than individual compounds themselves. This could help animals to save energy and to reduce the risk of being overwhelmed by the vast number of different odours in their environment.
Also, the discovery that there is a great deal of overlap in the composition of odours from different species suggests that blood-feeding arthropods, such as mosquitoes, may have to rely on combinatorial coding strategies to discriminate between different hosts. Combinatorial coding involves detecting the presence or absence of multiple compounds simultaneously. This approach is more reliable than detecting individual compounds, as it is less likely to be confounded by background noise or by the presence of similar compounds in other odours.
Additionally, the finding that vertebrate body odours carry little phylogenetic information is surprising, as it suggests that body odour has not been under strong selection pressure to evolve in a way that reflects evolutionary relationships between species. This could be because body odour is used for a variety of different purposes, such as communication, foraging, and predator avoidance. As a result, there may be no single optimal odour profile for any given species.
Finally, the finding that there is a high degree of consistency in the odour of individuals within a species suggests that body odour may play a role in individual recognition and social interactions. For example, animals may be able to identify other individuals of their own species based on their body odour. This could be important for maintaining social bonds and for avoiding inbreeding.
Overall, the McBride Lab provides a valuable foundation for future research on olfactory coding and evolution. The researchers’ findings suggest that animals may use a variety of different strategies to encode and discriminate between odours, depending on the specific task at hand. Their work also highlights the importance of understanding the statistics of natural odour spaces in order to develop a complete understanding of olfactory processing.
https://www.biorxiv.org/content/10.1101/2023.05.08.539789v2.full#F5
