Earth's Climate History Explains Life's Temperature Optima

Area of Science:

• Evolutionary biology
• Microbial ecology
• Geological oceanography

Background:

• Most life forms thrive within a narrow optimal temperature range, typically below 40°C.
• Earth's oceanic temperatures have remained stable between approximately 5°C and 37°C for over two billion years.

Purpose of the Study:

• To investigate the evolutionary constraints on life's thermal performance curves.
• To test if interspecific competition can explain the upper limit of optimal growth temperatures in prokaryotes.

Main Methods:

• Utilized Lotka-Volterra models to simulate interspecific competition.
• Modeled competition between organisms with varying temperature optima.

Main Results:

• Model simulations supported the hypothesis that organisms with temperature optima up to 37°C are most competitive.
• Results remained robust across various temperature response curve scenarios.

Conclusions:

• Ancient oceanic temperature stability likely constrained prokaryotic evolution to optimal growth temperatures below 40°C.
• Gene inheritance and co-evolution may have led to eukaryotes also adopting similar thermal optima.