DOI: 10.5061/dryad.6t1g1jx70
title: Data from: Weakly interacting species as drivers of ecological stability

description: Determining how individual species can act to moderate the stability of
 entire ecosystems is a pressing challenge in a world undergoing rapid
 environmental change. Here, we show that even very weakly interacting
 species with no discernible effect on ecological dynamics can contribute
 substantially to ecosystem stability. Further, the nature of this
 contribution depends on biotic context and both the type and complexity of
 interspecific interactions in the community. By manipulating multitrophic
 aquatic microcosm communities experimentally, we found that the
 contributions of a bacteriophage parasite to overall system stability
 following a pulse perturbation were variously stabilising, destabilising,
 and neutral, depending on the presence of competitor or predator species
 of its bacterial host. This was despite the phage itself having no
 detectable effect on the biomass or growth rates of its host. Our results
 demonstrate the pivotal importance of both weak and indirect interactions
 in moderating the stability of whole ecological networks and have profound
 implications for our ability to predict the consequences of perturbations
 on ecosystems.
description: # Weakly interacting species as drivers of ecological stability Dataset
 DOI: [10.5061/dryad.6t1g1jx70](10.5061/dryad.6t1g1jx70) ## Description of
 the data and file structure Microbial communities were assembled
 consisting of treatments with varying species combinations (7 replicate
 communities for 7 ). These communities were assembled in aquatic
 micorcosms and species densities and population trajectories monitored
 daily for a period of 10 days. We assessed the contribution of a
 bacteriophage to four components of community stability in each of our
 experimental communities (that is, their temporal variability, reactivity,
 resistance and resilience to a pulse perturbation). We combined this with
 tests of the direct effects of the bacteriophage on its host’s growth and
 competitive ability. This experimental framework allowed us to directly
 assess the relative impacts of direct and indirect species interactions on
 the wider community dynamics and stability. Paper available form
 Proceedings of the Royal Society Biological Sciences B ### Files and
 variables #### File: McClean\_ProcB\_micro.community.csv **Description:** 
 ##### Variables * Day: 1- 10 for start of community assembly to end of
 experiment.  * Microcosm: community ID * Treatment: Which species
 combination was present; B is B. subtilis, C= competitor bacteria S.
 marcescens. P is bacteriophage parasite, Para is predatory paramecium P.
 caudatum * Disturbed : Y (pulse disturbance), N (no disturbance)  *
 trt.phage: present (phage was present), absent (phage absent) * Species:
 bacillus (b. subtilis), kleb (klebsiella sp), paramecium (p.caudatum),
 phage (SPP! bacteriophage), serratia (s. marcescens) * Density: density of
 each species * ld: log10(density) #### File:
 McClean\_ProcB\_submit\_bs.growthdata.csv **Description:**  #####
 Variables * well: well ID in a 96 well plate * MICRO: microcosm (replicate
 ID) * media: treatment;  B is B. subtilis, C= competitor bacteria S.
 marcescens. P is bacteriophage parasite, Para is predatory paramecium P.
 caudatum * comm: simple (2 species) or comp (&gt;2 species)  * Disturbed:
 Y (disturbance present) or N (no disturbance) * factor.phage: treatment *
 factor.pred:treatment * factor.comp:treatment * phage: presence (Y) or
 absence (N) of phage * comp:presence (Y) or absence (N) of competitor
 bacteria * predator:presence (Y) or absence (N) of predator *
 ancestor: competitor species, predator, and ancestral strain. * lag
 time.hrs: lag time  * lag time SE.hrs: lag time SE * inflection time.hrs
 : Time at which the growth curve inflects (i.e., max growth acceleration).
 * max spec growth rate log od/hr: * max spec growth rate SE.log/OD.hr: *
 max log OD: #### File: McClean\_ProcB\_Submit\_LRRdata.csv
 **Description:**  ##### Variables * Microcosm: replicate ID * Treatment: 
 B is B. subtilis, C= competitor bacteria S. marcescens. P is bacteriophage
 parasite, Para is predatory paramecium P. caudatum * Phage: presence (Y)
 or absence (N) of phage  * trt: treatment  * Day: experimental day *
 meandendis: mean density in disturbed communities  * meandenundis: mean
 density in undisturbed communities  #### File:
 McClean\_ProcB\_submit\_stability.metrics.csv **Description:**  #####
 Variables * trt: experimental treatment ( B is B. subtilis, C= competitor
 bacteria S. marcescens. P is bacteriophage parasite, Para is predatory
 paramecium P. caudatum) * phage: presence (Y) or absence (N) of phage  *
 resistance: metric * reactivity :metric * resilience:metric *
 trt.tv:metric * phage.tv:metric * tv:metric #### File:
 McClean\_ProcB\_submit\_community.plot.data.csv **Description:**  #####
 Variables * Day: Experimetnal day  * Microcosm: replicate ID *
 Treatment:experimental treatment ( B is B. subtilis, C= competitor
 bacteria S. marcescens. P is bacteriophage parasite, Para is predatory
 paramecium P. caudatum) * trt.phage:: presence (Present) or absence
 (Absent) of phage  * trt.comp: presence (Present) or absence (Absent) of
 competitor bacteria  * trt.para:presence (Present) or absence (Absent) of
 paramecium * Disturbed : presence (Y) or absence (N) of disturbance *
 Species: bacillus (b. subtilis), kleb (klebsiella sp), paramecium
 (p.caudatum), phage (SPP! bacteriophage), serratia (s. marcescens) *
 Density: Population density of the species (in number of cells or
 colony-forming units). * ld:log10 Density  #### File:
 McCleanProcB\_submit.R **Description:** code for producing the metric,
 statistics and figures for the paper McClean et al 2025 Weakly INteracting
 Species as Drivers of Ecological Stability ProcB ## Code/software Data is
 all on cv Excel files. Code is an R script (free software).