Divergent gametic thermal performance and floral warming across an elevation gradient

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Physiology

Background:

• Species ranges exhibit diverse thermal environments, promoting local adaptation of thermal performance.
• Floral temperature critically impacts angiosperm reproductive success, but gametic thermal performance adaptation and its influence on floral evolution remain understudied.

Purpose of the Study:

• Investigate local adaptation of gametic thermal performance in Argentina anserina across an elevation gradient.
• Determine if variation in gametic thermal performance drives floral microenvironment evolution.

Main Methods:

• Characterized flowering season temperatures at high and low elevations.
• Generated thermal performance curves for pollen and ovules.
• Assessed floral microenvironment warming and the role of floral tissues.

Main Results:

• Pollen thermal optima were approximately 4°C higher in cool, high-elevation populations compared to warm, low-elevation populations.
• Intrafloral temperatures fell between mean and maximum temperatures.
• High-elevation flowers exhibited significantly greater warming, influenced by floral tissues, bringing temperatures closer to pollen optima.

Conclusions:

• Elevational divergence in floral warming suggests selection for gametophyte thermal demands.
• Floral warming mechanisms may be a key adaptation to local thermal environments, influencing reproductive success.