Temporal niche partitioning through olfactory cell type evolution

Temporal niche partitioning is a phenomenon where different species utilize the same resource at distinct times. The underlying mechanisms behind this behavior have remained a mystery. A study has revealed that Drosophila sechellia, a fruit fly species that specializes in consuming Morinda citrifolia noni, displays a narrow temporal preference for the most toxic, ripe fruit.

This preference helps D. sechellia minimize exposure to competition, parasitization, and microbial infection, which can occur during other stages of fruit development.

Chemical analysis of the noni fruit indicated that ketones are key odors associated with ripe fruit. Researchers conducted a comparative single-cell transcriptomic analysis, which revealed that D. sechellia has adapted the expression of a larval ketone receptor, Or45a, in an adult olfactory neuron population. This novel expression of Or45a is solely due to cis-regulatory changes and can independently detect the ripe noni aroma.

The researchers determined that Or45a is crucial for D. sechellia's preference for ripe noni, working in conjunction with another ketone receptor, Or85c/b. The neuron population of Or85c/b has expanded in D. sechellia, further supporting their unique temporal niche partitioning strategy. The study's findings offer a groundbreaking connection between cell type evolution and ecologically advantageous temporal niche partitioning.