DOI: 10.5061/dryad.z8w9ghxkz
title: Data for: Microbe-induced plant resistance alters aphid inter-genotypic competition leading to rapid evolution with consequences for plant growth and aphid abundance

description: Plants and insect herbivores are two of the most diverse multicellular
 groups in the world, and both are strongly influenced by interactions with
 the belowground soil microbiome. Effects of reciprocal rapid evolution on
 ecological interactions between herbivores and plants have been repeatedly
 demonstrated, but it is unknown if (and how) the soil microbiome could
 mediate these eco-evolutionary processes on a shared host plant. We tested
 the role of a plant-beneficial soil bacterium (Acidovorax radicis) in
 altering eco-evolutionary interactions between different aphid genotypes
 (Sitobion avenae; genotypes Sickte and Fescue) feeding on barley (Hordeum
 vulgare). We measured fecundity, longevity and population growth of two
 aphid genotypes reared separately or together (population mixture) on
 three different barley varieties that were inoculated with or without A.
 radicis. Results showed that across all plant varieties A. radicis
 increased plant growth and suppressed aphid populations via reduced
 longevity and fecundity. The strength of effect was dependent on aphid
 genotype and barley variety, while the direction of effect was altered by
 aphid population mixture. Using Lotka-Volterra modelling, we demonstrated
 that while A. radicis inoculation decreased growth rates for both aphid
 genotypes it increased the competitiveness of one genotype against the
 other. In general, in the presence of A. radicis, the Fescue aphid
 genotype became more inhibitory of Sickte aphids, while Sickte aphids
 facilitated the growth of Fescue aphids. Our work demonstrates that plant
 rhizosphere microbiomes exert community-level influences by mediating
 eco-evolutionary interactions between herbivores and host plants. By
 altering competitive interaction outcomes among aphids and thus impacting
 processes such as rapid evolution, soil microbes contribute to the short-
 and long-term structure and functioning of terrestrial habitats.
description: Data were collected from a glasshouse pot experiment in Jan-Feb
 2020. We used (1) three barley cultivars [Barbarella (Elsoms Seeds),
 Chevallier (New Heritage Barley Ltd), Irina (KWS)]; (2) two genotypes of
 the English grain aphid <em>Sitobion avenae</em> (L.) that
 have been maintained as low density stock populations on barley variety
 ‘Chanson’, including a dark brown genotype ‘Fescue’ and a pale pinkish
 coloured genotype ‘Sickte’; and (3) the rhizobacteria <em>Acidovorax
 radicis</em> N35.  <em>Experiment
 1:</em> Population growth. Using a fully-factorial design of the
 factors above, and including no-aphid, single aphid genotype, and a mixed
 aphid genotype population, the 24 treatments were replicated 8 times each.
 Individual barley plants in 10cm diameter pots were grown in a glasshouse
 (average temperature of 20°C), infested with four 3rd instar aphids
 (either 4 of one genotype or two of each genotype for the mixed
 populations), every plant covered with an air-permeable cover, and aphid
 numbers counted on days 7, 14, and 21. Plant height and biomass was also
 measured. Data were analysed in R using linear models and mixed effect
 models (repeated measure over time) for effects of experimental
 variables. <em>Experiment 2: S</em>urvival
 and fecundity. Using the same factorial design as above, the 24 treatments
 were replicated 6 times each. Individual barley plants were infested with
 four 3rd instar aphids as in expt1, five days later after aphid
 reproduction all adults were removed alongwith all except four 1st instar
 nymphs (either 4 of one genotype or two of each genotype for the mixed
 populations). Aphids were followeduntil adulthood and then offspring
 produced counted every 1-2 days with offspring removal, with adults
 followed and offspring removed until aphid death. Aphid lifetime
 fecundity, daily fecundity and longevity (survival) were caluclated and
 effect of experimental variables on these analysed using linear models and
 mixed effect models (repeated measure over time).
 <em>Modelling:</em> We modelled intergenotypic
 competition between a population of the aphid genotypes growing on the
 same host plant, via a Lotka-Volterra model. We fitted the data from the
 first experiment to this model, in order to quantify the effects of host
 genotype and the presence/absence of bacteria on the growth and
 interactions of the two aphid genotypes.
description: # Dataset: Microbe-induced plant resistance alters aphid inter-genotypic
 competition leading to rapid evolution with consequences for plant growth
 and aphid abundance Data
 were collected from a glasshouse pot experiment in Jan-Feb 2020. We used
 (1) three barley cultivars [Barbarella (Elsoms Seeds), Chevallier (New
 Heritage Barley Ltd), Irina (KWS)]; (2) two genotypes of the English grain
 aphid Sitobion avenae (L.) that have been maintained as low density stock
 populations on barley variety ‘Chanson’, including a dark brown genotype
 ‘Fescue’ and a pale pinkish coloured genotype ‘Sickte’; and (3) the
 rhizobacteria Acidovorax radicis N35.  Experiment 1 - population growth.
 Using a fully-factorial design of the factors above, and including
 no-aphid, single aphid genotype, and a mixed aphid genotype population,
 the 24 treatments were replicated 8 times each. Individual barley plants
 in 10cm diameter pots were grown in a glasshouse (average temperature of
 20°C), infested with four 3rd instar aphids (either 4 of one genotype or
 two of each genotype for the mixed populations), every plant covered with
 an air-permeable cover, and aphid numbers counted on days 7, 14, and 21.
 Plant height and biomass was also measured. Data were analysed in R using
 linear models and mixed effect models (repeated measure over time) for
 effects of experimental variables. Experiment 2 - survival and fecundity.
 Using the same factorial design as above, removing no aphid treatment the
 18 treatments were replicated three times each. Individual barley plants
 were infested with four 3rd instar aphids as in expt1, five days later
 after aphid reproduction all adults were removed along with all except
 four 1st instar nymphs (either 4 of one genotype or two of each genotype
 for the mixed populations). Aphids were followed until adulthood and then
 offspring produced counted every 1-2 days with offspring removal, with
 adults followed and offspring removed until aphid death. Aphid lifetime
 fecundity, daily fecundity and longevity (survival) were calculated and
 effect of experimental variables on these analysed using linear models and
 mixed effect models (repeated measure over time). Modelling. We modelled
 intergenotypic competition between a population of the aphid genotypes
 growing on the same host plant, via a Lotka-Volterra model. We fitted the
 data from the first experiment to this model, in order to quantify the
 effects of host genotype and the presence/absence of bacteria on the
 growth and interactions of the two aphid genotypes. ## Description of the
 data and file structure The excel file contains an explanation of each of
 the variables and the two datasets in three worksheets: (1) ReadME with
 variable explanations (2) DATA1_population growth&modelling data (3)
 DATA2_survival & fecundity NA = no relevant data for this treatment
 (e.g. no aphid data for 'no aphid' control plants) ##
 Code/Software Code for the modelling is included as three .Rdata files