About This Project

Symbiodinium is algae that reproduces in as little as 24 hours; 10,000 times faster than the average American woman! They also play crucial roles in the health of coral reefs, as they form mutualisms with reef organisms. I will examine how diverse communities of Symbiodinium can rapidly evolve in response to increased nutrients. Evolution of one partner could be key to the survival of the mutualism and to the persistence of a healthy ecosystem.

Ask the Scientists

What is the context of this research?

Coral reef ecosystems are rife with species that have evolved to endure nutrient-poor waters by forming mutualistic partnerships with Symbiodinium. These single-celled photosynthetic algae live inside of their hosts, bartering photosynthetic products for nitrogenous waste products. Resource mutualisms like these are inherently sensitive to changes in the traded resource in the environment. Because human agricultural practices and fossil fuel combustion have caused widespread increases in N deposition, this ecologically important mutualism may be affected.

This mutualism is characterized by differences in generation times: corals that live long lives are paired with unicellular algae with short lives. This means that corals have limited capacity for rapid adaptation in response to sudden changes in the environment. However, rapid evolution in their partners may buffer the effects of environmental disturbances upon their mutualism.

What is the significance of this project?

Coral reefs are among the most biodiverse ecosystems on earth, and among the most threatened by climate change. This study may have important conservation applications as it may provide insight into how important members of the ecosystem may respond to climate-induced changes in nutrient cycling. My study will address how a diverse symbiont population can rapidly evolve in response to a changing nutrient environment, a necessary prerequisite for mutualism evolution.

Models are now integrating ecological and evolutionary perspectives more frequently. According to a review by Haloin and Strauss, very few of these models do so while examining mutualistic interactions.

What are the goals of the project?

Many genotypes of Symbiodinium can live inside of a single host coral. I will consider how algal genetic diversity affects performance and how N-enrichment may alter this relationship. Genetic diversity forms the base upon which natural selection acts, assuming that differences in phenotype correlate with differences in fitness. Understanding the role of genetic diversity is crucial in understanding how selection pressures arising from changes in nutrient levels may affect the evolution of Symbiodinium within coral hosts.

Throughout my project, I will define “performance” as traits that will likely affect the mutualistic relationship between the host and algae such as cell size, population growth rate, photosynthetic rate, oxygen production, nitrogen consumption and carbon concentrations. I have three goals of this project:

1. To determine the performance success of various Symbiodinium genotypes exposed to different nutrient environments.

2. To determine the effects of genetic diversity on performance at different nutrient levels.

3. To address how these populations of varying diversity levels will evolve over six months, which encompasses several hundred generations.