Zylka, S. | bioRxiv Science

bioRxiv2025

Ecological cues orchestrate concerted courtship in a Drosophila host specialist

Mating decisions are often attributed to the sensory signaling between prospective sexual partners. Yet these interactions are also shaped by the broader environmental context in which they unfold, to appropriately align sexual arousal with reproductive opportunities. Here we show that in the host specialist Drosophila erecta mating is strictly contingent on the ecological and social environment generated as flies densely aggregate in groups on a food patch. We find that food volatiles directly promote male sexual arousal, triggering individuals to sample and pursue potential mates, giving rise to dynamic interactions across the group. The ensuing visual motion transforms each males visual field, which in turn further amplifies his arousal, generating a multisensory feedback loop that coordinately promotes courtship across individuals. D. erectas strict dependence on environmental cues appears latent in related species, such as D. melanogaster, where food odor can promote arousal but is dispensable for vigorous courtship. Comparative circuit analyses reveal that species-specific thresholds for sexual arousal reflect variation in how olfactory input modulates conserved nodes controlling courtship drive, rendering food volatiles a strict sensory gate only in D. erecta. Together, our findings highlight how ecological cues not directly tied to sexual signaling can profoundly influence reproductive behavior and reorganize the social landscape to ensure mating occurs in contexts where reproductive opportunities are abundant.

neuroscience↗

bioRxiv2022

Rapidly evolving genes underlie Aedes aegypti mosquito reproductive resilience during drought

Female Aedes aegypti mosquitoes impose a severe global public health burden as vectors of multiple viral pathogens. Under optimal environmental conditions, Aedes aegypti females have access to human hosts that provide blood proteins for egg development, conspecific males that provide sperm for fertilization, and freshwater that serves as an egg-laying substrate suitable for offspring survival. As global temperatures rise, Aedes aegypti females are faced with climate challenges like intense droughts and intermittent precipitation, which create unpredictable, suboptimal conditions for egg-laying. Here we show that under drought-like conditions simulated in the laboratory, females retain mature eggs in their ovaries for extended periods, while maintaining the viability of these eggs until they can be laid in freshwater. Using transcriptomic and proteomic profiling of Aedes aegypti ovaries, we identify two previously uncharacterized genes named tweedledee and tweedledum, each encoding a small, secreted protein that both show ovary-enriched, temporally-restricted expression during egg retention. These genes are mosquito-specific, linked within a syntenic locus, and rapidly evolving under positive selection, raising the possibility that they serve an adaptive function. CRISPR-Cas9 deletion of both tweedledee and tweedledum demonstrates that they are specifically required for extended retention of viable eggs. These results highlight an elegant example of taxon-restricted genes at the heart of an important adaptation that equips Aedes aegypti females with "insurance" to flexibly extend their reproductive schedule without losing reproductive capacity, thus allowing this species to exploit unpredictable habitats in a changing world.

neuroscience↗