DOI: 10.5061/dryad.280gb5mq9
title: Intra-specific variation in metal tolerance modulate competition between two marine diatoms

description: This project contains data for the manuscript Intra-specific
 variation in metal tolerance modulate competition between two marine
 diatoms. The experiments tests how different  toxic
 concentrations of heavy metals modulates competition between an
 artificially assembled community of Baltic Sea diatoms (four
 clonal strains each of the two
 diatom species Skeletonema marinoi (SM)
 and Thalassiosira  baltica (TB). Briefly we use
 toxic Dose Response curves (DRC) to model how inter and intra
 specific selection between strains is expected to be modulated
 under Cadmium, Copper and Silver stress. The stress level was set at the
 average 50% inhibition concentration (EC50) between all eight strains.
 Strains were mixed at even biomass based on Relative Chl a
 Fluorescence Units (RFU) and cultivated semi-continuously to maintain
 exponential growth. The growth of individual species was measured
 through microscopy observations and the photosynthetic capacity
 was monitored using Pulse Amplitude Modulation (PAM) fluorometry.
 A experimental design flow figure is included as a supplement.
 The complete functional set of scripts, statistical analysis, and
 graphical illustrations in R can be found on
 github: https://github.com/Bearstar85/Selection_Competition_2021 
description: The directories/sections break down the data into three components or experiments. Each directory contains data and a README file with more detailed metadata. <br>  <br> 1. DRC<br> Contains acute (72-h) toxic dose response data for all eight strains against seven heavy metals although competition is only modeled and experimentally tested under Ag, Cu and Cd stress. This is only mono-cultures observations. The concentrations of each metal is nominal in this dataset and experiments where carried out in 24-well plates, with 6 concentrations steps replicated 3 times, and 5 controls, with 1 mL culture per replicate. Culture density was measured using in vivo relative fluorescence units (RFU), and inhibition is computed based on specific growth rate estimates, scaled towards the control (so that 0 is no change in growth rate and 1 is no or negative growth). Dose response curves for <i>S. marinoi </i>strain RO5AC towards Cu in different media conditions is also included, mainly with or without EDTA. 2. Models<br> Results of deterministic selection model based on variability in intrinsic growth rate and predicted metal inhibition traits between strains. In the end (section 3), models are contrasted against experimental observations. This includes predicted strain specific inhibition values (using drc package in R) and specific growth rates, as well as predicted changes in biomass densities over time, and evolution of growth rates based on selection. 3. Competition<br> Experimental observational data of co-cultivation experiment, including changes in total community biomass (RFU) as well as species biomass based on microscopic observations. The latter was used to compute species-specific growth rates. Fv/Fm was also monitored using Pulse Amplitude Modulation (PAM) fluorometry.
description: There are generally very few missing datapoints, but in a manual
 curation of the dose respons curves &lt;0.2% of datapoints where
 omitted because they formed severe outliers. Also in the competition
 experiment the limit of detection of either species was 1 cell mL-1, and
 this was breached in several replicates towards the end, at which points
 the species is still represented by 1 cell mL-1 for plotting
 purposes.  For detailed description of the dose respons
 method see: 10.1016/j.aquatox.2020.105551 and for the model and
 competition experiments see associated ISME journal articel in
 press