Functional genetics of intraspecific ecological interactions in Arabidopsis thaliana

Abstract

Studying the genetic basis of traits involved in ecological interactions is a fundamental part of elucidating the connections between evolutionary and ecological processes. Such knowledge allows one to link genetic models of trait evolution with ecological models describing interactions within and between species. Previous work has shown that connections between genetic and ecological processes in Arabidopsis thaliana may be mediated by the fact that quantitative trait loci (QTL) with 'direct' effects on traits of individuals also have pleiotropic 'indirect' effects on traits expressed in neighbouring plants. Here, we further explore these connections by examining functional relationships between traits affected directly and indirectly by the same QTL. We develop a novel approach using structural equation models (SEMs) to determine whether observed pleiotropic effects result from traits directly affected by the QTL in focal individuals causing the changes in the neighbours' phenotypes. This hypothesis was assessed using SEMs to test whether focal plant phenotypes appear to mediate the connection between the focal plants' genotypes and the phenotypes of their neighbours, or alternatively, whether the connection between the focal plants' genotypes and the neighbours' phenotypes is mediated by unmeasured traits. We implement this analysis using a QTL of major effect that maps to the well-characterized flowering locus, FRIGIDA. The SEMs support the hypothesis that the pleiotropic indirect effects of this locus arise from size and developmental timing-related traits in focal plants affecting the expression of developmental traits in their neighbours. Our findings provide empirical insights into the genetics and nature of intraspecific ecological interactions. Our technique holds promise in directing future work into the genetic basis and functional relationship of traits mediating and responding to ecological interactions.

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

“…Broad-scale empirical and theoretical (e.g. [74]) efforts that address the relative importance of inter-and intra-specific effects and variation on community processes should also try to complement these fine-scale genetic mechanistic approaches [61]. As such, this second generation of research will require an interdisciplinary toolkit in model and non-model organisms and will help to build a cohesive and predictive framework between community ecology, Review.…”

“…The use of SEM in ecological and evolutionary field studies is growing, and represents an exciting and important avenue of future community genetics research (i.e. [58][59][60][61]). …”

“…With this information it will be possible to determine whether certain genes and phenotypic traits have similar consequences in diverse communities and ecosystems, and whether certain traits are more likely to evolve and affect ecological dynamics. In essence, a more mechanistic approach might enable us to make predictions about when a community genetics approach is warranted [5,11,61,80,81].…”

The quantitative genetics of indirect genetic effects: a selective review of modelling issues

“…The classical example of an IGE is the maternal genetic effect of a mother on the trait values of her offspring in a mammal (Dickerson, 1947;Willham, 1963;Falconer, 1965;Kirkpatrick and Lande, 1989). Other examples of IGEs are mortality due to cannibalistic interactions in domestic chicken (Muir, 1996(Muir, , 2005, the effect of competition among trees on growth rate in bark diameter (Brotherstone et al, 2011), the outcome of dyadic interactions in deer , social behaviours in microorganisms (Crespi, 2001), size, developmental and fitness-related traits in Arabidopsis (Mutic and Wolf, 2007;Wolf et al, 2011), and growth rate in Medaka (Ruzzante and Doyle, 1991).…”

Social structure and indirect genetic effects: genetics of social behaviour

“…Microorganisms cooperate to achieve a variety of behaviours such as foraging, quorum sensing and the coordination of biofilm formation (Crespi, 2001;West et al, 2006). Ecological interactions in plant systems contribute to the size and fitness-related traits of neighbours (Mutic & Wolf, 2007;Wolf, Mutic & Kover, 2011;Andersson, 2014), which has led to accounting for IGEs in the optimization of breeding programs (Muir, 2005). Examples of phenotypes under shared genetic control from the animal kingdom include social dominance interactions in red deer Cervus elaphus (Wilson et al, 2011), antipredator behaviour in Poecilia reticulate guppies (Bleakley & Brodie, 2009), growth rate in medaka Oryzias latipes (Ruzzante & Doyle, 1991), female choosiness in Pacific field crickets Teleogryllus oceanicus (Bailey & Zuk, 2012), egg-laying date variance in common gulls Larus canus (Brommer & Rattiste, 2008), as well as aggression in pigs Sus scrofa (Camerlink et al, 2013) and mink Neovison vison (Alemu et al, 2014).…”