DOI: 10.5061/dryad.p5hqbzkv5
title: Competition increases risk of species extinction during extreme warming

description: Temperature and interspecific competition are fundamental drivers of
 community structure in natural systems and can interact to affect many
 measures of species performance. However, we know surprisingly little
 about the extent to which competition affects extinction temperatures
 during extreme warming. This information is important for evaluating
 future threats to species from extreme high-temperature events and heat
 waves, which are rising in frequency and severity around the world. Using
 experimental freshwater communities of rotifers and ciliates, this study
 shows that interspecific competition can lower the threshold temperature
 at which local extinction occurs, reducing time to extinction during
 periods of sustained warming by as much as two weeks. Competitors may
 lower extinction temperatures by altering biochemical characteristics of
 the natural environment that affect temperature tolerance (e.g., levels of
 dissolved oxygen, nutrients, and metabolic wastes) or by accelerating
 population decline through traditional effects of resource depletion on
 life history parameters that affect population growth rates. The results
 suggest changes in community structure in space and time could drive
 variability in the upper thermal limits.
description: Please see methods section in corresponding paper.
description: All files are in .txt or .csv format. 
description: # COMPETITION INCREASES RISK OF SPECIES EXTINCTION DURING EXTREME WARMING
 Author: Paul Bendiks Walberg () Summary:
 We know surprisingly little about whether competition affects extinction
 temperature during periods of extreme warming. Using experimental
 freshwater communities of rotifers and ciliates, this study showed that
 interspecific competition can lower the temperature at which local
 extinction occurs, reducing time to extinction during periods of sustained
 warming by as much as two weeks. The results suggest changes in community
 structure in space and time could drive variability in the upper thermal
 limits. ## DATA FILES: data_density_detail.csv (also
 data_density_detail.xls) This file, presented in both .csv and .xlsx
 format, includes the complete density time series for the three test
 species. Data are presented in Fig. 1. species = test species (euplotes,
 coleps, rotaria) factor = temperature factor (increasing, constant) temp =
 temperature (degrees C) day = corresponding day p1-p6 = density (#/ml) of
 polyculture replicates 1-6 m1-m6 = density (#/ml) of monoculture
 replicates 1-6 data_density_mean.csv This file includes mean density for
 the three test species. Data are analyzed in the ANOVA AND POST HOC TUKEY
 TEST ON DENSITY (see file ‘R_code.txt’). Results are presented in
 Supplementary material, Table S1(a-b). rep = replicate # spec = species
 factor (euplotes, coleps, rotaria) temp = temperature factor (incr =
 increasing, cons = constant) comp = composition factor (poly =
 polyculture, mono = monoculture) density = mean density (#/ml) across time
 series data_Te_De.csv This file includes temperature of extinction (Te)
 and days to extinction (De) data for the three test species. Data are
 presented in Fig. 2 and analyzed in the ANOVA AND POST HOC TUKEY TEST ON
 TEMPERATURE OF EXTINCTION (see file ‘R_code.txt’). Results are presented
 in Supplementary material, Table S2(a-c). rep = replicate # spec = species
 factor (euplotes, coleps, rotaria) comp = composition factor (poly =
 polyculture, mono = monoculture) Te = temperature of extinction (°C) De =
 days to extinction data_density_trial.csv This file includes density data
 for all 10 species in monoculture and polyculture from trial experiments.
 Data are presented in Supplementary material, Fig S1, and analyzed in the
 ANOVA ON DENSITY IN TRIAL EXPERIMENTS (see file ‘R-code.txt’). Results are
 presented in presented in Supplementary material, Table S3(a-b). rep =
 replicate # spec = species factor (names of each of 10 study species) comp
 = composition factor (polyculture, monoculture) density = density (#/ml)
 at 26.0C data_richness.csv This file includes species richness in
 increasing-polyculture communities at each temperature. Data are presented
 in Fig. 3. temp = temperature p1-p6 = species richness in replicates 1-6
 of increasing polyculture communities R_code.txt This file includes all
 code used to analyze density, Te and richness data in R (version 4.2.2).
 The code requires downloading and installing the ‘CAR’ (version 3.1-2) and
 ‘dplyr’ (version 1.1.2) packages.