Genotype‐by‐Genotype Interactions Modified by a Third Species in a Plant‐Insect System

Abstract

Community genetics examines how genotypic variation within a species influences the associated ecological community. The inclusion of additional environmental and genotypic factors is a natural extension of the current community genetics framework. However, the extent to which the presence of and genetic variation in associated species influences interspecific interactions (i.e., genotype x genotype x environment [G x G x E] interactions) has been largely ignored. We used a community genetics approach to study the interaction of barley and aphids in the absence and presence of rhizosphere bacteria. We designed a matrix of aphid genotype and barley genotype combinations and found a significant G x G x E interaction, indicating that the barley-aphid interaction is dependent on the genotypes of the interacting species as well as the biotic environment. We discuss the consequences of the strong G x G x E interaction found in our study in relation to its impact on the study of species interactions in a community context.

Quantitative trait loci mapping of phenotypic plasticity and genotype–environment interactions in plant and insect performance

“…Both mapping populations gave similar patterns of phenotypic effects, in that biomass could be increased, decreased or unaffected by environmental factors (aphid infestation and rhizobacterial supplementation) compared with the control. This agrees with our previous results [12] on this experimental system. A decrease in barley biomass was observed in more lines in the aphid environment compared with the P. aeruginosa 7NSK2-supplemented environment (compared with the control), and the combined aphid and P. aeruginosa 7NSK2-supplemented environment led to a decrease in biomass in the greatest proportion of lines.…”

“…We used two doubled haploid (DH) mapping populations, Steptoe  Morex (SÂM) and Oregon Wolfe Barley (OWB). Parental lines from the SÂM population were previously investigated for the presence of GEIs within the tri-trophic ecosystem used here [12]. The second mapping population (OWB) was used to test whether GEIs and phenotypic plasticity resulting from multi-species interactions are specific to mapping population or prevalent throughout both mapping populations.…”

Community genetics: what have we accomplished and where should we be going?

“…Studies that simultaneously manipulate the genetic composition of multiple species and other environmental attributes will be a necessary first step towards understanding the importance of G Â G Â E interactions on demography and community structure (e.g. [55,56]). …”

Can Temperature and Water Availability Contribute to the Maintenance of Latitudinal Diversity by Increasing the Rate of Biotic Interactions?

“…a GxG interaction in fitness, e.g. Ferrari et al 2007;Tétard-Jones et al 2007). Therefore, theoretically, in an environment in which biotic interactions are more important as selective agents than abiotic factors, where soft selection is more frequent, and where each GxG encounter can potentially contribute to an increase in fitness GxE, genetic diversity should be more easily maintained.…”

“…Ferrari et al 2007;Tétard-Jones et al 2007) across interacting genotypes (analogously to GxE interactions -Byers 2005) could be used to support the hypothesis that the fine-grained nature of biotic interactions can enhance the maintenance of genetic diversity (hypothesis 5). Also, experimentally manipulating the order of interacting genotypes and estimating fitness can serve to demonstrate the potential effect of interaction drift.…”