Adaptive thermal plasticity enhances sperm and egg performance in a model insect

Area of Science:

• Evolutionary biology
• Reproductive biology
• Climate change adaptation

Background:

• Rising global temperatures threaten biodiversity, particularly reproductive success and fertility.
• Reproductive traits are highly sensitive to thermal stress, necessitating adaptation mechanisms.
• The insect model *Tribolium* (flour beetles) offers insights into thermal adaptation in warm-temperate and tropical species.

Purpose of the Study:

• To investigate the potential for thermal adaptation in sperm and egg function in *Tribolium* flour beetles.
• To determine if gamete phenotypic plasticity in response to temperature changes is adaptive.
• To quantify the reproductive benefits of gamete plasticity under varying thermal regimes.

Main Methods:

• Exposing *Tribolium* flour beetles to increased temperatures during adult development.
• Analyzing changes in sperm morphology (length) and egg size.
• Conducting thermal translocation experiments to assess reproductive performance under different production and environmental temperatures.

Main Results:

• Males produced shorter sperm and females laid larger eggs following developmental temperature increases.
• Gametes produced in warmer conditions exhibited superior reproductive performance in warmer environments, and vice versa.
• Gamete plasticity significantly enhanced male reproductive success (doubled) and female offspring production (increased by one-third) in warmer environments.

Conclusions:

• Gamete phenotypic plasticity is an adaptive mechanism for *Tribolium* beetles facing rising and variable global temperatures.
• Reproductive traits, though sensitive, possess adaptive potential to cope with thermal challenges.
• These findings highlight the capacity of vital reproductive traits to buffer against climate change impacts on biodiversity.