Adaptive genetic variation mediates bottom-up and top-down control in an aquatic ecosystem

Area of Science:

• Eco-evolutionary dynamics
• Community genetics
• Ecosystem ecology

Background:

• Intraspecific variation influences ecosystem processes but studies often focus on single species or trophic levels.
• Local adaptation leads to ubiquitous intraspecific variation, yet its combined effects across multiple taxa are poorly understood.

Purpose of the Study:

• To investigate how combined intraspecific phenotypic variation in multiple species affects ecosystem ecology.
• To understand the interplay between top-down and bottom-up forces driven by intraspecific variation.

Main Methods:

• Large-scale aquatic mesocosm experiment using black cottonwood (Populus trichocarpa) and three-spined stickleback (Gasterosteus aculeatus).
• Assessed the impact of genetic variation in cottonwood productivity and stickleback morphology on prey abundances and nutrient availability.

Main Results:

• Genetic variation in cottonwood productivity mediated top-down effects of stickleback on prey.
• Invertebrate prey abundances and phosphorus levels were determined by the interaction between cottonwood variation and stickleback morphology.
• These interactive effects were comparable in strength to predator addition.

Conclusions:

• Intraspecific variation is an under-appreciated driver of community structure and ecosystem function.
• A multi-trophic perspective is essential for understanding the role of rapid evolution in ecological patterns.