Local climatic adaptation in a widespread microorganism

Area of Science:

• Microbiology
• Evolutionary Biology
• Climate Change Research

Background:

• Understanding local adaptation is crucial for predicting organismal responses to climate change.
• Microorganisms, like the wild yeast Saccharomyces paradoxus, are key models for studying adaptation due to their rapid generation times.
• Few studies have investigated climate adaptation in microorganisms across heterogeneous environments.

Purpose of the Study:

• To investigate the role of heterogeneous climate on the local adaptation of North American Saccharomyces paradoxus populations.
• To determine if climatic variation explains fitness differences among yeast strains.
• To explore the genetic basis of adaptation in response to climate.

Main Methods:

• Assessed fitness components of Saccharomyces paradoxus strains across a range of temperatures.
• Analyzed the relationship between climatic variation and observed fitness variation.
• Investigated genetic structure and population divergence along a north-south gradient.

Main Results:

• Significant among-strain variation in fitness components was observed, but not fully explained by local climate.
• Genetic divergence into distinct groups along a north-south cline largely explained fitness variation, suggesting adaptation to different climatic conditions.
• Within these distinct groups, fitness components correlated with specific climatic conditions, confirming local adaptation.

Conclusions:

• Ubiquitous microorganisms like Saccharomyces paradoxus exhibit local adaptation and possess standing genetic variation for climate-related traits.
• Global climate change may drive further adaptation within these microbial groups or alter their geographic distributions.