Male fertility thermal limits predict vulnerability to climate warming

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Assessing species vulnerability to climate warming is crucial for conservation.
• Tropical and mid-latitude species are considered most at risk due to proximity to thermal limits.
• Current vulnerability assessments often overlook evolutionary adaptation potential.

Purpose of the Study:

• To evaluate extinction risk and adaptation to warming in tropical and widespread Drosophila species.
• To determine if male fertility thermal limits are better predictors of vulnerability than CTmax.
• To investigate the capacity for evolutionary adaptation to rising temperatures.

Main Methods:

• Experimental evolution was used to simulate climate warming.
• Extinction risk and adaptation were assessed in tropical and widespread Drosophila species.
• Male fertility thermal limits and CTmax were measured and compared to species distributions.

Main Results:

• Tropical Drosophila species exhibited higher extinction rates than widespread species under experimental warming.
• Male fertility thermal limits, not CTmax, more accurately predicted species' current distributions and laboratory extinction.
• Little evidence of significant adaptive responses to warming was observed across all tested species.

Conclusions:

• Species may be closer to their critical thermal limits than previously assumed.
• Evolutionary adaptation and phenotypic plasticity are unlikely to fully mitigate extinction risks from climate warming.
• Conservation strategies should consider a broader range of physiological limits, such as male fertility, for accurate vulnerability assessments.