Fertility
Pupae were allocated to 3D-printed floating racks in pre-heated
water-baths set to 23°C (‘no hardening’) or 36°C (‘hardening’) for 1h as
above. Immediately following hardening, they were transferred into
pre-heated water baths at 23°C (‘benign’) or 38°C (‘stress’), chosen as
the highest temperature not resulting in significant mortality from a
prior study (Walsh et al. 2020). After four hours at their
treatment temperature, vials were subsequently removed from the
water-baths and returned to benign temperatures (23°C). Emerging males
were collected and immediately moved into individual vials with 4
sexually mature virgin female partners each. These groups were moved
into new vials every 2 days for 7 times, giving a total of 8 vials
across 16 days where fertility was recorded. Estimates ofDrosophila survival rates in nature suggest 16 days represents a
substantial portion of their expected adult lifespan (Powell 1997).
Males were deemed as qualitatively fertile at any given time-point if
there was evidence of larvae present in the vial (either via direct
observation of larvae or observing larval tracks in the food).