DOI: 10.5061/dryad.0p2ngf1xw
title: Functional redundancy in natural pico-phytoplankton communities depends on temperature and biogeography

description: Biodiversity affects ecosystem function, and how this relationship will
 change in a warming world is a major and well-examined question in
 ecology. Yet, it remains understudied for pico-phytoplankton communities,
 which contribute to carbon cycles and aquatic food webs year-round.
 Observational studies show a link between phytoplankton community
 diversity and ecosystem stability, but there is only scarce causal or
 empirical evidence. Here, we sampled phytoplankton communities from two
 geographically related regions with distinct thermal and biological
 properties in the Southern Baltic Sea, and carried out a series of
 dilution/regrowth experiments across three assay temperatures. This
 allowed us to investigate the effects of loss of rare taxa and establish
 causal links in natural communities between species richness and several
 ecologically relevant traits (e.g. size, biomass production, and oxygen
 production), depending on sampling location and assay temperature. We
 found that the samples’ bio-geographical origin determined whether and how
 functional redundancy changed as a function of temperature for all traits
 under investigation. Samples obtained from the slightly warmer and more
 thermally variable regions showed overall high functional redundancy.
 Samples from the slightly cooler, less variable, stations showed little
 functional redundancy, i.e. function decreased when species were lost from
 the community. The differences between regions were more pronounced at
 elevated assay temperatures. Our results imply that the importance of rare
 species and the amount of species required to maintain ecosystem function
 even under short-term warming may differ drastically even within
 geographically closely related regions of the same ecosystem. 
description: Detailed methods are provided in the SI document available
 through Biology Letters. If any unclarities remain, the authors
 (Duyi Zhong, Luisa Listmann, Maria-Elisabetta Santelia, C-Elisa Schaum) will provide more details upon request. 
description: Here, we provide some information on the individual files. We are
 not uploading raw flow cytometry data (but present a representative
 exported file, plus cytograms) - those data are available from the authors
 upon reasonable request.  File
 "all_slopes_combined - pooledforstations.csv" contains the data
 that Figure 02 in the main text is based on. Temp is the assay temperature
 in degrees C, Region refers to the sampling region,statID refers to the
 station (replicates are pooled on the station level),slope is the
 slope,sd_slope is the standard deviation of that slope, and trait is the
 trait under investigation. File
 "20200615_flowphenotypes,csv" contains an example of flow
 cytometry data, where individual events (corresponding to the cellsmL
 column) have been summarised to yield a mean and sd for SSC, FL2,FL3, and
 FL4.   File
 "growthrates_inocculation_real.csv" contains the growth rates
 and the inocculation cell numbers with their deviations. CellsmL_day0 is
 the number of cells measured at inocculation, SD_cellt0 is the ±1SD of
 this measurement. Growthrate and SD_growth are the growth rate and ±1SD of
 a sample. Region refers to the sampling region, repID to the replicate
 number within region, Dilution is the dilution and assaytemp is the assay
 temperature in degrees C. File
 "20200217_alldata_metab_biod" contains the non-log transformed
 metabolic rates. Region, AssayTemp, repID, Dilution are as above. Columns
 11-13 have the NP,R, and GP data per cell per hour (µmol O2). NP_real
 takes into account that during culture, the experimental units were
 exposed to a 12/12 light:dark cycle, so that they would have been
 photosynthesising for 12, but respiring for 24 hours. 
  File "20200606_timetoK.csv" contains the time points
 at which carrying capacity was reached. Region is the sampling
 region, Temp is the assay temperature in degrees C, Dilution is the level
 of dilution, StatID refers to the station number, K_reached_at_day is the
 day at which the baranyi model predicts that K is reached given the shape
 of the growth curve. File
 "sizebeads_before_service.png" shows the distribution of size
 beads on forward and side scatter before the instrument was
 serviced.  File
 "sizebeads_after_service.png"shows the distribution of size
 beads on forward and side scatter before the instrument was
 serviced.  File
 "20200715_results_decomposition.docx" provides detailed
 information on the output of the decomposition analysis carried out in
 order to estimate variability in the two basins under
 investigation File "biod_biom_justplot.R" is
 the R script used for plotting the richness/function plots, and also
 contains representative code for the mixed models (all other mixed models
 follow the same scheme) File
 "Duyi_loss_of_biomass_biodiversity" is the R script to fit
 growth curves (baranyi) to data in order to obtain µmax and K
 values  A step by step guide by Props et al (2016) on
 how to use the pheno-flow package to estimate  diversity from flow
 cytometric data can be found here
 https://github.com/rprops/Phenoflow_package.  The
 cytograms have all necessary information in the title.