Biology subjects

Barbour, M. A.

Publications and source records attributed to Barbour, M. A..

6 recordsLinked to original sources

bioRxiv2026

Epistasis and an oligogenic architecture underlie the strength of a plant-herbivore interaction

1. Interaction strength between consumers and resources is a fundamental driver of eco-evolutionary dynamics, and its genetic architecture is key to predicting the pace of such dynamics. Our understanding of this architecture is limited for three reasons: (i) defense phenotypes do not necessarily translate to interaction strength; (ii) interaction strength is difficult to measure in ways tied to consumer-resource theory; and (iii) association studies typically prioritize detecting large-effect loci rather than characterizing whether interactions are polygenic (many small-effect genes) or oligogenic (few large-effect genes). 2. We address these gaps by examining how genomic variation in the plant Arabidopsis thaliana influences interactions with the aphid herbivore Lipaphis pseudobrassicae in a greenhouse experiment. We grew 390 accessions spanning the species' natural range and measured aphid per-capita population growth as our interaction-strength metric. To test whether a previously identified plant defense gene (AOP2) acts additively or epistatically with other defense loci, we integrated our estimates of aphid population growth with public data on defense chemistry and gene expression. To determine whether the genetic architecture of interaction strength was polygenic or oligogenic, we used a Bayesian sparse linear mixed model that partitions these two components. 3. AOP2 showed epistasis with two other defense genes (MAM1 and GS-OH), indirectly modifying aphid population growth via the production of a specific defense compound (glucosinolate 2-hydroxy-3-butenyl). More broadly, interaction strength showed an oligogenic architecture: top single nucleotide polymorphisms (SNPs) occurred at low minor allele frequencies (< 3%) and grouped into six linkage disequilibrium blocks, including candidate genes outside canonical plant defense pathways. These six blocks explained 47% of the genetic variance in interaction strength, with only 3% additional variance attributable to polygenic effects. 4. Taken together, these results show that plant genomic variation modifies herbivore interaction strength through epistasis among defense genes and rare alleles at few loci. This oligogenic architecture imposes multiple constraints on the potential for rapid evolution, highlighting the need to integrate genomic effects into eco-evolutionary models.

ecology↗

bioRxiv2025

The roles of space and food web complexity in mediating ecological recovery

Landscape-scale ecological restoration is a key strategy for halting and reversing biodiversity decline. However, ensuring the long-term sustainability of restoration efforts requires guiding the recovery of complex ecological systems with many interdependent species at a landscape scale. Due to these challenges, our understanding of recovery trajectories remains limited. Using experiments and metapopulation models, we explore how the spatial configuration of communities and food web complexity jointly influence species recovery at different spatial scales. We find that the number and spatial placement of communities affects the colonisation of empty habitat patches, but does not influence population recovery in patches where communities are introduced. Food web complexity reduces the recovery of lower trophic levels, both at population and metapopulation scales. However, this negative effect may be partially mitigated at higher levels of food web complexity. Our results demonstrate that the joint consideration of spatial configuration and species interactions could enhance the effectiveness of restoration actions.

ecology↗

bioRxiv2022

Genome-wide association study highlights escape from aphids by delayed growth in Arabidopsis thaliana

Field studies have shown that plant phenological and architectural traits often explain substantial variation in herbivory. Although plant genes involved in physical and chemical defense are well studied, less is known about the genetic basis underlying effects of plant growth traits on herbivory. Here, we conducted a genome-wide association study (GWAS) of aphid abundance in a field population of Arabidopsis thaliana. This field GWAS detected a significant peak on the third chromosome of A. thaliana. Out of candidate genes near this significant genomic region, a mutant of a ribosomal gene (AT3G13882) exhibited slower growth and later flowering than a wild type under laboratory conditions. A no-choice assay with the turnip aphid, Lipaphis erysimi, found that aphids were unable to successfully establish on the mutant. These findings suggest the potential role of growth-related genes in altering herbivore abundance.

ecology↗

bioRxiv2020

Genetic diversity increases food-web persistence in the face of climate warming

Genetic diversity provides the raw material for species to adapt and persist in the face of climate change. Yet, the extent to which these genetic effects scale at the level of ecological communities remains unclear. Here we experimentally test the effect of plant genetic diversity on the persistence of an insect food web under a current and future warming scenario. We found that plant genetic diversity increased food-web persistence by increasing the intrinsic growth rates of species across multiple trophic levels. This positive effect was robust to a 3{degrees}C warming scenario and resulted from allelic variation at two genes that control the biosynthesis of chemical defenses. Our results suggest that the ongoing loss of genetic diversity may undermine the persistence and functioning of ecosystems in a changing world. One Sentence SummaryThe loss of genetic diversity accelerates the extinction of inter-connected species from an experimental food web.

ecology↗

bioRxiv2019

Ecological character displacement destabilizes food webs

Ecological character displacement is an adaptive process that generally increases phenotypic diversity. Despite the fact that this diversification is due to an eco-evolutionary feedback between consumers competing for shared resources, its consequences for food-web dynamics have received little attention. Here, I study a model of two consumers competing for two shared resources to examine how character displacement in consumer attack rates affects resource abundances and the resilience of food webs to perturbations. I found that character displacement always strengthened consumer-resource interactions whenever consumers competed for resources that occurred in different habitats. This increase in interaction strength resulted in lower resource abundances and less resilient food webs. This occurred under different evolutionary tradeoffs and in both simple and more realistic foraging scenarios. Taken together, my results show that the adaptive process of character displacement may come with the ecological cost of decreasing food-web resilience.

ecology↗

bioRxiv2019

Phenotypic evolution is more constrained in simpler food webs

Global change is simplifying the structure of ecological networks; however, we are currently in a poor position to predict how these simplified communities will affect the evolutionary potential of remaining populations. Theory on adaptive landscapes provides a framework for predicting how selection constrains phenotypic evolution, but often treats the community context of evolving populations as a "black box". Here, we integrate ecological networks and adaptive landscapes to examine how changes in food-web complexity shape evolutionary constraints. We conducted a field experiment that manipulated the diversity of insect parasitoids (food-web complexity) that were able to impose selection on an insect herbivore. We then measured herbivore survival as a function of three key phenotypic traits. We found that more traits were under selection in simpler vs. more complex food webs. The adaptive landscape was more neutral in complex food webs because different parasitoid species impose different selection pressures, minimizing relative fitness differences among phenotypes. Our results suggest that phenotypic evolution becomes more constrained in simplified food webs. This indicates that the simplification of ecological communities may constrain the adaptive potential of remaining populations to future environmental change. "What escapes the eye, however, is a much more insidious kind of extinction: the extinction of ecological interactions." Janzen (1974)

evolutionary biology↗