Disturbance decreases genotypic diversity by reducing colonization: Implications for disturbance-diversity feedbacks

Area of Science:

• Ecology
• Evolutionary Biology
• Marine Botany

Background:

• Eco-evolutionary dynamics explore how ecology and evolution maintain biodiversity.
• Disturbance impacts species diversity via ecological and evolutionary colonization/extinction.
• Limited empirical data exists on disturbance effects on genotypic diversity within populations.

Purpose of the Study:

• To experimentally test how disturbance affects genet colonization and extinction in Zostera marina (eelgrass).
• To investigate the relationship between disturbance frequency and genotypic richness in eelgrass populations.

Main Methods:

• A 2-year field experiment in northern California.
• Mimicked goose grazing disturbance by clipping eelgrass leaves at varying frequencies.
• Monitored genet colonization (gain) and extinction (loss) dynamics.

Main Results:

• Greatest new genet colonization occurred in the absence of disturbance.
• Clipping (disturbance) had negligible effects on genet extinction.
• A negative relationship was observed between clipping frequency and net genotypic richness changes.

Conclusions:

• Disturbance, specifically simulated grazing, negatively impacts net genotypic richness in eelgrass.
• Increased flowering and facilitation in undisturbed plots may drive higher colonization rates.
• A feedback loop exists where disturbance reduces genotypic diversity, potentially impacting ecosystem resilience.