Adaptation and Plasticity of Nannochloropsis sp. in Response to Seasonal and Geographic Climate Variation

TL;DR

Nannochloropsis microalgae show strong environmental plasticity, allowing them to adapt to varying light and temperature conditions across different locations and seasons.

Contribution

The study reveals that Nannochloropsis exhibits broad phenotypic plasticity, which may hinder genetic adaptation in natural, fluctuating environments.

Findings

Nannochloropsis strains showed only minor performance differences after long-term exposure to diverse climates.

Thermal performance varied more by season than by geographic location.

Light performance was influenced by both season and site, highlighting the role of environmental plasticity.

Abstract

Phytoplankton respond to their environment through genetic adaptation and plasticity to maintain fitness. This poses challenges when growing microalgae for industrial applications because, inherently, outdoor mass cultivation may lead to adaptations that alter desirable phenotypic traits and environmental niches. Here, we used common garden experiments to quantify the plasticity and adaptive responses to seasonal and geographic climate variation of Nannochloropsis, a microalga commonly used in biotechnology. An initially monoclonal strain was grown outdoors across four locations in Hawaii, Texas, California, and New Mexico. Following 17 and 22 months of cultivation outdoors, we collected samples during winter and summer, respectively, and we compared strains' growth from the four sites across temperature and light gradients in the laboratory. Despite hundreds of generations of exposure to divergent climates, with ~20°C and three‐fold differences in daily light intensity, strains showed only minor differences in performance. Thermal performance varied more among seasons than sites, whereas light performance varied with both season and site. Our study indicates that Nannochloropsis exhibits broad plasticity in response to light and temperature, which may inhibit genetic adaptation in space or time. Highly variable field conditions, with daily and seasonal climate fluctuations, may favor plasticity and prevent the rapid adaptation often seen in laboratory studies of microorganisms in constant environments.

Figures