Chaetoceros simplex cultures, were obtained from population strain CCMP 200 (National Center for Marine Algae and Microbiota, NCMA).
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Evolution experiment:
\nEight populations were grown at 31 \u00b0C, and one was maintained as a control at 25 \u00b0C in regular L1 medium (884 \u03bcm NO3\u2212).
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At 31 \u00b0C, four populations remained in regular L1 medium (884 \u03bcm NO3\u2212), while the other four received nitrogen\u2010reduced L1 medium (5 \u03bcm NO3\u2212);
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Populations were maintained in 50 mL polycarbonate culture flasks, at 100 \u03bcmol quanta m\u22122 s\u22121 cool white fluorescent light on a 14/10 h day/night cycle. We gently inverted and randomly repositioned flasks daily. Every three days c. 10^6 cells (never < 6 \u00d7 10^5 cells) from each population were transferred to fresh media. We monitored populations by measuring in vivo optical density daily (436 nm wavelength absorbance) using a Shimadzu UV\u20102401PC spectrophotometer before and after each transfer
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Growth rate calculations:
\nWhen more than two biomass observations (optical density or fluorescence, depending on the experiment) within the exponential growth phase were available, we calculated population growth rates (day\u22121), as the slope of the linear regression of ln(biomass) vs. time (days). Alternatively, when biomass measurements were made every 2\u20133 days, we calculated growth rate as
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(lnB2-LnB1)/(t2-t1)
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where B is biomass and t is time (days) and the number of generations within a particular time range, \u0394t, as
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(u/ln2)^\u0394t
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where u is growth rate.\u00a0
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Calculations were made with R, and scripts can be downloaded from: https://github.com/MariaArangurenGassis/PhytoEvolutionPaper2019.
\nMore details in Aranguren-Gassis et al. 2019, Ecology Letters.
Daily growth rates of 8 populations of Chaetoceros simplex grown at 31C and control population at 25C, in regular L1 medium (884 \u03bcm NO3\u2212) or nitrogen\u2010reduced L1 medium (5 \u03bcm NO3\u2212).
BCO-DMO Processing Notes:
\n- added conventional header with dataset name, PI name, version date
\n- modified parameter names to conform with BCO-DMO naming conventions
\n- reduced precision of Growth_rates from 9 to 1 decimal places.