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

Abstract

Community genetic studies generally ignore the plasticity of the functional traits through which the effect is passed from individuals to the associated community. However, the ability of organisms to be phenotypically plastic allows them to rapidly adapt to changing environments and plasticity is commonly observed across all taxa. Owing to the fitness benefits of phenotypic plasticity, evolutionary biologists are interested in its genetic basis, which could explain how phenotypic plasticity is involved in the evolution of species interactions. Two current ideas exist: (i) phenotypic plasticity is caused by environmentally sensitive loci associated with a phenotype; (ii) phenotypic plasticity is caused by regulatory genes that simply influence the plasticity of a phenotype. Here, we designed a quantitative trait loci (QTL) mapping experiment to locate QTL on the barley genome associated with barley performance when the environment varies in the presence of aphids, and the composition of the rhizosphere. We simultaneously mapped aphid performance across variable rhizosphere environments. We mapped main effects, QTL Â environment interaction (QTLÂE), and phenotypic plasticity (measured as the difference in mean trait values) for barley and aphid performance onto the barley genome using an interval mapping procedure. We found that QTL associated with phenotypic plasticity were co-located with main effect QTL and QTLÂE. We also located phenotypic plasticity QTL that were located separately from main effect QTL. These results support both of the current ideas of how phenotypic plasticity is genetically based and provide an initial insight into the functional genetic basis of how phenotypically plastic traits may still be important sources of community genetic effects.

Epigenetic Basis of Morphological Variation and Phenotypic Plasticity inArabidopsis thaliana

“…Similar results were obtained in drought and nutrient stress experiments, in which phenotypic plasticity was much higher in epiRILs than in the Col-0 wild type and highly heritable (Zhang et al, 2013). However, PP is also observed in conventional RIL populations (Lacaze et al, 2009;Tétard-Jones et al, 2011;ElSoda et al, 2014). It is difficult to compare the epigenetic with the genetic contribution to phenotypic plasticity, as epigenetic variation might contribute to phenotypic variation in conventional RIL populations when the epigenetic variation associates with the genetic markers (Schmitz et al, 2013a).…”

Integrating Phenotypic Plasticity Within an Ecological Genomics Framework: Recent Insights from the Genomics, Evolution, Ecology, and Fitness of Plasticity

“…It involves studying how certain genotypes affect the distribution, abundance, and evolution of other genotypes within a community, and what genes underlie heritable community traits Hersch-Green et al 2011). Community genetics of plasticity has received increased interest over the last several years (Rowntree et al 2011;Tétard-Jones et al 2011), particularly as plasticity's role in community ecology has been documented (Agrawal 2001;Fordyce 2006) (Fig. 5.7).…”

“…Experimental work is limited, but a recent study likely foreshadows things to come: the interactions between barley, aphids, and rhizobacteria were measured, along with barley and aphid plasticity across rhizobacterial environments. QTL for barley and aphid plasticity were mapped on to the barley genome, thus identifying gene regions in one species that influenced plasticity in another species, as mediated by a third species (Tétard-Jones et al 2011). Predictions regarding the role of plasticity in community genetics are few, but recent modeling work suggests that plasticity may facilitate community stability in tritrophic systems to a greater extent than genetic variation (Kovach-Orr and Fussmann 2012).…”

Forward from the crossroads of ecology and evolution

“…Although Wolf et al [47] use a single species model here, this approach could be easily adapted for the study of interspecific interactions among genotypes, such as those illustrated in the previous paper by Whitlock et al [22]. Tétard-Jones et al [48] also explore the genetic basis of IGEs, but in this case using a tritrophic system of rhizobacteria, barley (Hordeum vulgare) and aphids (Sitobion avenae). They examine how changes in the rhizobacterial environment can influence aphid fitness via the intermediate host plant by mapping aphid and barley traits, and the plasticity of those traits onto the barley genome across rhizobacterial environments.…”