Maintenance of Diversity through Multiple Timescales of Variation

Abstract

Understanding the maintenance of diversity in phytoplankton is important because they are the base of the food web and they play a major part in biogeochemical cycles including the carbon cycle, which affects how the biosphere reacts to climate change. Diversity can be maintained through resource fluctuation because species can evolve different strategies to thrive under different conditions. These strategies include being able to grow the fastest, being able to store the most resources, or being able to use resources more efficiently, thus being the best competitor under limited resources. Nutrient supply in the ocean likely varies over multiple time scales (e.g., seasonal variation vs. storms); however, we do not understand how multiple frequencies of variation affects phytoplankton communities. To test the role of multiple frequencies of variation, I am using a model describing how phytoplankton respond to varying nutrient supply. I compared how the community structure during conditions where there were two pulse frequencies differ from communities under one-pulse frequency conditions. Under one-pulse conditions it was reiterated that species with different strategies did better under competition at different periods. As the pulse periods increased there were clear shifts in the community structure with respect to the strategies. However, when a second pulse frequency was added, pulse periods where species with one strategy usually dominated, were found to contain a co-existence between species with multiple strategies. In short, it was found that multiple frequencies of resource variation allow for a greater diversity of strategies present in the community.