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

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.