Joseph K. Bailey

A genetic basis to community repeatability and stability

Recent studies have shown that genetically based traits of plants can structure associated arthropod and microbial communities, but whether the effects are consistent and repeatable across years is unknown. If communities are both heritable (i.e., related individuals tend to support similar communities) and repeatable (i.e., the same patterns observed over multiple years), then plant genetics may also affect community properties previously thought to be emergent, such as stability. Using replicated clones of narrowleaf cottonwood (Populus angustifolia) and examining an arthropod community of 103 species, we found that (1) individual tree genotypes supported significantly different arthropod communities, which exhibited broad-sense heritability; (2) these findings were highly repeatable over three consecutive years (repeatability = 0.91) indicating that community responses to individual tree genotypes are consistent from year to year; (3) differences among tree genotypes in community stability (i.e., changes in community composition over multiple years) exhibited broad-sense heritability (H(C)2 = 0.32). In combination, these findings suggest that an emergent property such as stability can be genetically based and thus subject to natural selection.

Welcome to the neighbourhood: interspecific genotype by genotype interactions in Solidago influence above‐ and belowground biomass and associated communities

Intra- and interspecific plant-plant interactions are fundamental to patterns of community assembly and to the mixture effects observed in biodiversity studies. Although much research has been conducted at the species level, very little is understood about how genetic variation within and among interacting species may drive these processes. Using clones of both Solidago altissima and Solidago gigantea, we found that genotypic variation in a plants neighbours affected both above- and belowground plant traits, and that genotype by genotype interactions between neighbouring plants impacted associated pollinator communities. The traits for which focal plant genotypic variation explained the most variation varied by plant species, whereas neighbour genotypic variation explained the most variation in coarse root biomass. Our results provide new insight into genotypic and species diversity effects in plant-neighbour interactions, the extended consequences of diversity effects, and the potential for evolution in response to competitive or to facilitative plant-neighbour interactions.

A geographic mosaic of trophic interactions and selection: trees, aphids and birds

Genetic variation in plants is known to influence arthropod assemblages and species interactions. However, these influences may be contingent upon local environmental conditions. Here, we examine how plant genotype‐based trophic interactions and patterns of natural selection change across environments. Studying the cottonwood tree, Populus angustifolia, the galling aphid, Pemphigus betae and its avian predators, we used three common gardens across an environmental gradient to examine the effects of plant genotype on gall abundance, gall size, aphid fecundity and predation rate on galls. Three patterns emerged: (i) plant genotype explained variation in gall abundance and predation, (ii) G×E explained variation in aphid fecundity, and environment explained variation in gall abundance and gall size, (iii) natural selection on gall size changed from directional to stabilizing across environments.

From genes to ecosystems: a genetic basis to ecosystem services

Ecosystems provide services, many of which are regulated through species interactions. Emerging research in the fields of community and ecosystem genetics indicate that genetic variation in one species can influence species interactions and affect subsequent patterns of energy flow and nutrient cycles. Because there can be a genetic basis to community- and ecosystem-level processes, evolutionary processes that alter standing genetic variation can have extended consequences that matter to patterns of biodiversity and ecosystem function that exist on the landscape. Here we explore some emerging areas of research in the field of community and ecosystem genetics and discuss the general importance of this approach to evolutionary ecology.

Intraspecific Plant–Soil Feedbacks Link Ecosystem Ecology and Evolutionary Biology

The interactions among plants, soil biotic communities, and soil are increasingly shown to be important in ecology but are underappreciated in evolutionary biology. Through genetic interactions among co-occurring taxa, plants and the biotic soil community influence the fitness and performance of each over time. At the intraspecific level, variation in plant traits leads to conditioning of soil physical and chemical properties and biotic communities which can have positive, neutral, or negative feedbacks to plants. These feedbacks can have positive fitness effects that lead to divergence of traits in plants. Building on the growing literature showing the genetic basis to plant conditioning of soils and the role of plant–soil feedback in determining plant performance and fitness, we review: (1) evolutionary theory linking plants and soils (which broadly includes soil physical and chemical properties as well as the biotic community); (2) provide examples of genetically based variation in plant–soil feedback (PSF); and (3) identify the evolutionary consequences of PSF. Together, modeling and empirical results show that intraspecific interactions among plants and soils vary across environments that can lead to geographic variation in feedback responses and evolutionary divergence. Both local adaptation and maladaptation are equally likely to occur which can drive divergence in plant traits and ecosystem function in different directions. Overall these results demonstrate that plant–soil interactions are ideal for demonstrating eco-evolutionary feedbacks which has implications for understanding a range of population, community, and ecosystem outcomes in a changing world.