Transgenerational Heat Exposure Triggers Unexpected Compensatory Sex Ratio Responses in a Temperature-Sensitive Fish...

Area of Science:

• Environmental science
• Ecology
• Genetics

Background:

• Rising global temperatures pose a threat to species with environmental sex determination, potentially skewing population sex ratios and leading to demographic collapse.
• Multigenerational adaptation mechanisms are often overlooked in predictions of species' responses to climate change.

Purpose of the Study:

• To investigate the transgenerational impacts of elevated temperature on sex ratios and reproductive physiology in European sea bass (Dicentrarchus labrax).
• To explore the potential for adaptive mechanisms counteracting demographic imbalances caused by climate change.

Main Methods:

• Rearing three generations (F0-F2) of European sea bass under control and elevated temperatures over a decade (>3000 fish).
• Analyzing sex ratios and gonad histology in ~1500 juveniles of the F2 generation across eight thermal history groups.
• Examining the influence of ancestral thermal exposure on sex determination and reproductive physiology.

Main Results:

• Direct developmental exposure to elevated temperatures induced masculinization.
• A novel compensatory parental effect was observed: paternal lines with baseline sex biases produced offspring with opposite sex ratio skews under heat stress.
• Heat-exposed males showed delayed spermatogenesis, while female gonadal development was unaffected by temperature.

Conclusions:

• Predicting climate change impacts requires a multigenerational perspective, considering transgenerational plasticity.
• Complex compensatory responses can enhance demographic resilience, modulated by genetic variability.
• Further studies are needed across taxa to determine the prevalence of this phenomenon and its implications for population responses to global warming.