The double-edged effect of environmental fluctuations on evolutionary rescue

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Contemporary evolution can prevent extinction in changing environments.
• Evolutionary rescue is crucial for species survival.
• Environmental fluctuations are increasing due to global changes.

Purpose of the Study:

• Investigate the impact of environmental fluctuations on evolutionary rescue.
• Understand how varying fluctuation amplitudes affect adaptation.
• Explore the mechanisms behind environmental fluctuations' effects on evolutionary rescue.

Main Methods:

• Conducted evolution experiments using green algae (Chlorella vulgaris).
• Manipulated salinity levels to simulate deteriorating environmental trends with varying fluctuation amplitudes.
• Utilized mathematical modeling to analyze population dynamics and trait variance.

Main Results:

• Increasing fluctuation amplitude around a deteriorating trend initially slowed algal growth.
• At higher stress levels (1M NaCl), populations with large fluctuations survived, while those with small or no fluctuations did not.
• Mathematical models suggested increased trait variance under large fluctuations promotes adaptive evolution.

Conclusions:

• Environmental fluctuations have a dual role in evolutionary rescue, with both negative and positive impacts.
• Large fluctuations can enhance adaptive evolution by increasing population trait variance.
• Further research is needed to fully understand evolutionary rescue dynamics in natural fluctuating environments.