Functional tradeoffs determine species coexistence via the storage effect

Area of Science:

• Ecology
• Plant Biology
• Evolutionary Biology

Background:

• Understanding biodiversity generation and maintenance is a core ecological question.
• Species coexistence mechanisms often imply performance tradeoffs, but empirical evidence in natural systems is limited.

Purpose of the Study:

• To investigate if functional tradeoffs underpin species coexistence in a Sonoran Desert winter annual plant community.
• To quantify the strength of the storage effect (a key coexistence mechanism) in this system.
• To link species' physiological traits to their long-term population dynamics and coexistence.

Main Methods:

• Utilized a 25-year dataset of plant vital rates (birth, death, growth).
• Combined demographic data with morphological and physiological measurements.
• Developed a novel framework to quantify the storage effect.

Main Results:

• Functional tradeoffs, specifically between growth capacity and low-resource tolerance, explain species differences in population recovery and coexistence.
• Species' demographic responses to environmental variation (e.g., precipitation) are decoupled due to these tradeoffs.
• The storage effect was assessed and found to be influenced by these species-specific functional differences.

Conclusions:

• Physiological differences in resource uptake and allocation drive partially decoupled population dynamics, promoting biodiversity.
• This study provides empirical evidence linking functional traits to long-term community dynamics and coexistence in a natural system.
• The findings offer a framework for understanding biodiversity maintenance in more complex ecological communities.