Species richness and intraspecific variation interactively shape marine diatom community functioning

The data and code provided here is used to analyze and visualize all data associated with the manuscript "Species richness and intraspecific variation interactively shape marine diatom community functioning" which is under review at L&O Letters and is authored by Patrick K. Thomas, Marrit Jacob, Esteben Acevedo-Trejos, Helmut Hillebrand, and Maren Striebel.

Data should be analyzed in R or R studio. The code should execute automatically with no modifications by the user as long as the four csv files are placed in the same working directory that R is set to. The R project (.Rproj) file may also be opened directly to create an R project that is automatically set to the correct directory.

ABSTRACT:Biodiversity generally increases productivity in ecosystems; however, this is mediated by the specific functional traits that come with biodiversity loss or gain and how these traits interact with environmental conditions. Most biodiversity studies evaluate effects of species richness alone, despite our increasing understanding that intraspecific diversity can have equally strong impacts. Here, we manipulate both species richness and intraspecific richness (i.e., number of distinct strains) in marine diatom communities to explicitly test the relative importance of species and strain richness for biomass and trait diversity in six distinct temperature/nutrient environments. We show that species and strain richness both have significant effects on biomass and growth rates, but more importantly they interact with each other, indicating that cross-species diversity effects depend on within-species diversity and vice versa. This intertwined relationship thus calls for more integrative approaches quantifying the relative importance of distinct biodiversity components and environmental context on ecosystem functioning.