RAPID EVOLUTION OF COMPETITVE ABILITY
RESEARCHERS: Dávid U. Nagy (PI), Ragan M. Callaway, Christoph Rosche
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Understanding whether invasive species evolve increased competitive ability in their non-native ranges is central to invasion biology, yet empirical evidence remains inconsistent and often limited by small sample sizes, and simplified competition metrics. In this project, we experimentally quantified competitive responses and competitive effects in 100 native and 165 non-native populations, sampled across broad and comparable environmental gradients. Plants were grown either alone, in intraspecific competition, or in interspecific competition. Our results show that non-native populations exhibit consistently higher competitive ability than native populations, but only under interspecific competition, indicating that rapid evolution has specifically enhanced interactions with heterospecific competitors rather than conspecifics. Overall, this work highlights the key role of rapid evolutionary change in shaping competitive interactions and invasion dynamics at continental scales, with important implications for predicting future range expansion under global change.
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Status: Under review in Nature Communications.
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POPULATION GENOMICS OF A COSMOPOLITAN WEED
RESEARCHERS: Marilia S Lucas (PI), Walter Durka, Christoph Rosche, Stefan Michalski, Chris Barratt, Renske Onstein
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Invasive plant species present a growing ecological and economic challenge, often rapidly adapting to new environments through complex demographic and evolutionary processes. Invasion genomics offers powerful tools to disentangle these processes by linking demographic history, adaptation, and human-mediated dispersal at global scale. In this project, we used double-digest restriction site-associated DNA sequencing (ddRADseq) to investigate the genetic diversity, demographic history, and local adaptation in 280 Conyza canadensis populations distributed across the Northern Hemisphere.
We aimed to answer the following research questions: (i) What are the dominant patterns of population structure, and how do they differ between native and non-native ranges? (ii) How has migration and human-mediated dispersal shaped gene flow and population connectivity across the global range? (iii) Which environmental variables drive genetic differentiation, and can these be used to predict adaptation in non-native populations? By addressing these questions, we aimed to shed light on the evolutionary and ecological mechanisms that have facilitated the global invasion success of Conyza canadensis.
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Status: Major revision in Molecular Ecology.
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BELOWGROUND RESPONSES TO DROUGHT
RESEARCHERS: Christoph Rosche (PI), Julian Selke, David Nagy, Kristian Peters, Henriette Uthe, Nicole van Dam, Ylva Lekberg
Understanding how plants respond to drought is essential for predicting the impacts of global change on species distributions. However, little is known about the eco-evolutionary drivers of intraspecific variation in belowground drought responses. In this project, we study fine root traits, root exudation profiles, and fungal root colonization across native and non-native Conyza canadensis populations, grown under dry and mesic greenhouse conditions.
We tested the hypothesis that non-native populations have evolved a different strategy to cope with drought than native ones. In particular, we predicted that native populations respond to drought with pronounced changes in fine root morphology, including increased specific root length (a "do-it-yourself" strategy). In contrast, we predicted non-native populations to show limited morphological plasticity but increased interactions with mutualist fungi as mediated through increased and targeted root exudation (a " cry-for-help" strategy).
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Status: In preparation to be submitted by June 2026.
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FIELD HERBIVORY
RESEARCHERS: Manzoor A. Shah (PI), Ragan M. Callaway, S. Luke Flory, Ylva Lekberg, Robert W. Pal
Through field observations, this project investigates the extent of herbivory damage on Conyza canadensis and the diversity of herbivores associated with the species in native versus non-native ranges. This research has important implications for understanding the invasiveness of Conyza canadensis and its interactions with local ecosystems
Status: In preparation to be submitted by February 2026.
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PANGENOMICS AND GLYPHOSATE RESISTANCE
RESEARCHERS: Caio Brunharo (PI), Christoph Rosche, Jesse R. Lasky
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Glyphosate is an herbicide widely used in agriculture throughout the world. Its overuse has led to the widespread evolution of resistance. Although first reported in the early 2000’s, the genetic mechanisms of resistance remain unknown. This project resequenced populations of Conyza canadensis collected around the world to map the glyphosate resistance variants. In addition, we characterized the genomic structure and variation in both resistant and susceptible populations.
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Status: In preparation to be submitted by end of 2026.
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AMONG POPULATION VARIATION IN ABSOLUTE GENOME SIZE
RESEARCHERS: Arpad E. Thoma (PI), Marilia S. Lucas, Christoph Rosche, Patrik Mráz
Genome size is increasingly recognized as an ecologically relevant trait that can influence plant physiology, performance, and adaptation. However, most studies have focused on interspecific comparisons, while intraspecific genome size variation remains underexplored, particularly in the context of biological invasions. This project explored how absolute genome size varies among populations across a broad spatio-environmental gradient, and how this variation relates to traits linked to successful establishment and invasiveness. We focused on Conyza canadensis populations across its native and non-native ranges, testing whether genome size correlates with environmental gradients, phenotypic trait variation, and genetic structure.
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Status: In preparation to be submitted by mid-2026.
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ENHANCED MUTUALISM IN THE NON-NATIVE RANGE
RESEARCHERS: Min Sheng (PI), Wenyan Duan, Xin Li, Ylva Lekberg
The enhanced mutualism hypothesis offers a new perspective to explore the invasion mechanisms of exotic plants, but it remains unclear how the community structure and function of arbuscular mycorrhizal fungi (AMF) may influence adaptive evolution. This project conducted field surveys and common garden experiments with Conyza canadensis along latitudinal gradients in China to quantify the rate of rapid evolution among Conyza canadensis populations and how this contributes to AMF community structure. The research also aimed to explore genetic factors involved in the recruitment of AMF and the elucidation of their function, as well as explanation of enhanced mutualism-mediated invasion mechanisms of Conyza canadensis.
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Status: Data analysis in progress.
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BELOWGROUND MECHANISMS OF COMPETITION MEDIATED BY ROOT EXCUDATES
RESEARCHERS: Dávid U. Nagy (PI), Julian Selke, Kristian Peters, Henriette Uthe, Nicole M. van Dam, Christoph Rosche
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Plant competition is shaped not only by above-ground interactions but also by below-ground chemical processes. In this project, we investigate how root exudates mediate competitive interactions across native and non-native populations. Using 100 populations, we conducted a greenhouse experiment with intra- and interspecific competition, quantifying both above-ground performance and below-ground responses, including root biomass allocation. We collected root exudates from focal plants and performed non-targeted eco-metabolomic analyses to assess how competition alters exudate composition and chemical diversity. Competition consistently shifted root exudate profiles, indicating plastic and population-specific below-ground responses. In a complementary phytometer experiment, we tested the allelopathic effects of these exudates and found that exudates from non-native populations suppressed early seedling growth of competitor species, whereas native exudates did not differ from controls. These results demonstrate that below-ground chemical interactions play a central role in competitive differentiation, helping to explain among-population variation in competitive ability beyond above-ground traits.
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Status: Data analysis in progress.​
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RELATIVE AND INTERACTIVE ROLES OF ENEMIES AND MUTUALISTS IN INVASION
RESEARCHERS: S. Luke Flory (PI), Yukti V. Taneja, Ylva Lekberg
Plants engage in interactions with other species that may influence their establishment, growth, and dispersal. Invasion success is affected by multi-trophic interactions with herbivores, pathogens, and mutualists, both belowground and aboveground. Below-ground mutualisms, like arbuscular mycorrhiza (AM) fungi, aid in nutrient acquisition, while above-ground herbivory can impact biomass and fecundity, often triggering a defense response at the cost of growth. This project aimed to study the relative roles of aboveground herbivory and belowground mycorrhizal associations in driving success of invasive plant populations across non-native compared to native ranges. This project was conducted at the University of Florida, where biotic interactions were manipulated, including aboveground insect herbivores and belowground AM mutualist in a fully factorial design to examine role of multiple biotic interactions in success of Conyza canadensis populations across native and invaded ranges.
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Status: Data analysis in progress.
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VOLATILE COMMUNICATION IN RESPONSE TO HERBIVORY
RESEARCHERS: Karin Schrieber (PI), Tobias Demetrowitsch, Carolin Böttcher, Elham Mehri, Eric Folz
Plants that are attacked by herbivores change the composition of leaf-emitted volatile organic compounds. Neighbouring receiver plants can eavesdrop on such signals to induce their chemical defences already before herbivores arrive. It is well known that such plant-plant communication is highly plant and herbivore species-specific. Moreover, there is evidence that it is even kin-specific, i.e., only closely related plant individuals are able to eavesdrop on each other’s signals, while rather distantly related individuals can’t use them as a cue. This add-on project investigated such private channels using Conyza canadensis and its specialist herbivore Uroleucon erigeronense (an Aphid) as a study system. The experimental setup comprised plant populations from America and Eurasia, which form a relatedness gradient (underpinned by population genomic data) and differ systematically in their history of exposure to herbivory. It can thus provide comprehensive insight into the evolution of private channels.
Status: Data analysis in progress.
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SALINITY STRESS RESPONSE
RESEARCHERS: Abdelmajid Khabbach (PI), Mohamed Libiad, David Nagy, Said Louahlia
This project focused on the eco-evolutionary aspects of plant adaptation to salinity stress. The aim was to understand how evolutionary responses to salinity differ among Conyza canadensis populations from native and non-native ranges, as well as among populations within these ranges, by investigating the effect of brackish water on their germination capacity. This research will provide valuable insights into how Conyza canadensis adapts to different environmental conditions, contributing to our broader understanding of plant invasion biology and the species' invasive potential.
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Status: Data analysis in progress.
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PHENOLOGICAL DIFFERENTIATION AND REPRODUCTIVE STRATEGIES ACROSS GENETIC LINEAGES
RESEARCHERS: Dávid U. Nagy (PI), Robert Rauschkolb, J.F. Niek Scheepens
Phenology is a key element of plant adaptation, linking environmental conditions to growth, reproduction, and fitness. In this project, we investigate the timing of major vegetative and reproductive stages, as well as biomass allocation and reproductive output, across nearly 200 populations spanning native and non-native ranges. Rather than strong differentiation between ranges, we found that phenological variation is primarily structured by genetic clustering. Populations originating from northern regions generally showed later bolting and vegetative development, but earlier flowering, whereas southern populations bolted earlier and invested more strongly in vegetative growth and reproduction. These results highlight phenology and resource allocation as evolutionarily flexible traits shaped by population history and climatic origin, providing insight into how genetic lineages contribute to the global success of this species.
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Status: Data analysis in progress.
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ACCUMULATION OF PATHOGENS AS DRIVER OF INVASION SUCCESS
RESEARCHERS: Arpad E. Thoma (PI), Christoph Rosche, Ylva Lekberg
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Recent research indicates that Conyza canadensis associates with more beneficial arbuscular mycorrhizal fungal (AMF) communities in its non-native as compared to its native range, which appears to enhance growth and fitness of non-native relative to native populations. Additionally, more recent projects show that non-native Conyza canadensis populations do not appear to escape pathogens but are rather associated with a greater variety of fungal pathogens. However this is pattern is proportionally higher in the adjacent rhizosphere than in their roots indicating that pathogenes in the non native range have a lower probability to enter the roots of Conyza canadensis than in the native range. Using a plant-soil feedback experiment, this project aims to investigate pathogen accumulation of non-native Conyza canadensis populations and their effect on competitors.
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Status: Start in April 2026.​
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CLIMATE ADAPTATION AND LAND USE STUDIES
RESEARCHERS: Caio Brunharo (PI), Jesse R. Lasky
By integrating remote sensing, historical global agricultural land use, population genomics, global climatic data, and adaptive trait analysis, this project aims to unravel the eco-evolutionary dynamics of Conyza canadensis. Specifically, it investigates the genetic and physiological mechanisms of climate adaptation, the role of habitat heterogeneity and disturbances in driving plasticity, and the interaction of climate and land use in shaping genotypes. Additionally, the project will develop distribution models to predict the future global spread of Conyza canadensis under climate change scenarios.
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Status: Project under development.
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TRAIT DIFFERENTIATION OF EARLY AND LATE INVADERS ALONG AN URBANIZATION GRADIENT
RESEARCHERS: Dávid U. Nagy (PI), J.F. Niek Scheepens
Urban environments impose strong and novel selection pressures on plants, providing natural laboratories to study invasion dynamics. In this project, we investigate interspecific trait differentiation between the early invader Conyza canadensis and the later-arriving Conyza sumatrensis along an urbanization gradient in Frankfurt am Main, Germany. While Conyza canadensis colonized Central Europe as early as the 17th century, originating from temperate regions, Conyza sumatrensis has only been recorded since the 1980s and originates from warmer, subtropical regions. Using field surveys across urban, suburban, and rural sites, we quantify variation in reproductive traits, leaf characteristics, and biomass production to test whether the two species differ in their ecological strategies and responses to urbanization. Building on these observations, we plan complementary greenhouse experiments to examine how key stressors (e.g., competition, drought, and heat) interact with urban origin. This project aims to link invasion history, climate origin, and urban adaptation to understand how closely related invaders succeed in cities.
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Status: Project under development.
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