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Data from: Experimental heatwaves reduce the effectiveness of ejaculates at occupying female reproductive tracts in a model insect

Vasudeva, Ramakrishnan1; Sales, Kris2; Thomas, Paul3; Gage, Matthew3

Research facility: School of Biological Sciences
Published Oct 10, 2024 on Dryad. https://doi.org/10.5061/dryad.dv41ns25d

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Abstract

Globally, heatwaves have become more common, with hazardous consequences on biological processes. Recent research using a model insect (Tribolium castaneum) found that 5—day experimental heatwave conditions damaged several aspects of male reproductive biology, while females remained unaffected. However, females’ reproductive fitness may still be impacted, as insects can typically store sperm from multiple males in specialised organs for prolonged periods. Consequently, using males which produce sperm with green fluorescent protein (GFP)-tagged sperm nuclei, we visualised in vivo whether thermal stress affects the ejaculate occupancy across female storage sites under two scenarios; i) increasing time since insemination, and ii) in the presence of defending competitor sperm.

We reconfirmed that sperm from heatwave-exposed males sired fewer offspring with previously mated females, and provide new evidence for in vivo distributions of heat stress-exposed males’ sperm. Sperm from heatwave-exposed males occupied a smaller area across the females’ storage sites, at lower densities. Overall, sperm occupancy decreased with time since insemination. However, heat stress-exposed males’ sperm were not lost at a relatively faster rate. The sperm from the first male to mate dominated the long-term storage site. However, the offensive ability of heat stress-exposed males’ sperm to penetrate this site was similar to controls.