The proposal was submitted under the title: “POREXPAN: Local adaptation of plant POpulations during Range EXPANsions: the effect on life-history traits and genetic variability” by the following members of the Network:
Centre for Ecological Research (Maria Mayol & Miquel Riba), Barcelona – Spain
National Institute for Agricultural and Food Research and Technology (Santiago C. González-Martínez), Madrid – Spain
University of Lausanne (John Pannell), Lausanne – Switzerland
National Research Council (G. Giuseppe Vendramin), Firenze – Italy
Here is the Abstract:
The analysis and forecasting of the impact of global change on biodiversity rarely incorporate the effects of evolutionary changes and past demographic history of species and their populations. However, there is growing evidence that they can have broad impacts on species
range, community composition and ecosystem services, with potential consequences for human health and welfare. Thus, the scope of current ecological models to support action-taking is severely limited. The dilemma posed to organisms by current trends of global (climate) change is simple: (i) to adjust to new conditions and/or (ii) to shift their ranges tracking favorable environments. Evidence for evolution in response to climate change is accumulating, and there is also ample evidence that current climate change is driving the expansion of numerous plant and animal populations towards higher elevations and latitudes. Though dispersal and adaptation are often presented as alternative mechanisms, both interact in complex ways. First, natural selection operates on complex, integrated phenotypes, so evolutionary predictions for individual traits may fail under conflicting selective pressures.
Second, range shifts usually involve new selective pressures to which individuals and populations are confronted. The interplay among these new selective pressures with demography, and how they affect relevant life-history traits during range-shifts is currently unknown. Third, demographic processes linked to range expansions might pose additional constraints on the evolutionary potential of species and populations on their expanding ranges. In particular, strong and consecutive bottlenecks during range expansions can reduce fitness in
colonization-front populations because of limited genetic variability and the accumulation of deleterious mutations (expansion load). In this project, we propose to investigate the effects of range expansions on life-history traits and genetic variability (adaptive potential) using two non-model plant species, Leontodon taraxacoides and Mercurialis annua, along postglacial expansion routes. Both species are particularly well suited for experimentation and genomic analyses since they are short-lived (annual), have known breeding systems and relatively small genomes, and extensive genomic resources are already available. Our approach includes: 1) the assessment of the genetic basis of the phenotypic variability in key life-history traits (dispersal ability, growth, reproductive effort, phenology, and defense response) and their correlations, through common garden experiments; 2) the characterization of signatures of range expansions in genes and gene networks associated with key adaptive traits and, particularly, the level of accumulation of deleterious mutations in colonization fronts (i.e. expansion load); 3) the association of genes and gene networks with adaptive traits measured in common gardens to determine their molecular basis and provide a first insight on the genetic architecture of life-history traits in the context of range expansions. Our approach will allow us to test current theory on evolutionary consequences of range expansions at both molecular and quantitative trait levels, to identify candidate genes and traits associated with colonization of new environments, and to evaluate the evolutionary potential of expanded populations for future adaptation.
A new collaborative proposal has been submitted to CAPS-ERANET under the title ‘Molecular adaptation to biotic and abiotic stressors in the context of range expansion and rapid climate change’. This project is participated by most of the Mercurialis community, including:
University of Lausanne (DEE and DBMV Departments), Lausanne – Switzerland
National Institute for Agricultural and Food Research and Technology (INIA), Madrid – Spain
Centre for Ecological Research (CREAF-UAB), Barcelona – Spain
Université Catholique de Louvain (UCL), Louvain-la-Neuve – Belgium
Heidelberg University (COS-HD), Heidelberg – Germany
Institute of Soil Science and Plant Cultivation – State Research Institute (IUNG), Pulawy – Poland
Tel Aviv University (TAU), Tel Aviv – Israel
National Research Council (CNR), Firenze – Italy
Université Montpellier 2 (ISEM-UM2), Montpellier – France
Université Lille 1 (GEPV-Lille), Lille – France
The project summary follows:
Plants that have expanded their geographic ranges tend to show lower genetic diversity at their new range margins, and thus may have lost their adaptive potential as a result of the repeated genetic bottlenecks that occur during colonisation. In outcrossing species, however, range-edge populations might maintain sufficient genetic variation for continued responses to selection, either because colonisation bottlenecks are less severe for outcrossers, or because outcrossing facilitates continued gene flow into range-edge populations from elsewhere. We propose to test this hypothesis by studying the impact of range expansions and natural selection on the genome and patterns of gene expression of the European plant Mercurialis annua, a wind-pollinated dioecious (and thus outcrossing) annual plant that currently occupies a wide environmental range in Europe following range expansion from an eastern Mediterranean refugium. To test recent theory about how local adaptation interacts with range shifts at the genomic level, we will carry out genome and transcriptome analysis of natural and evolved genotypes in a set of common gardens established along range-expansion routes and environmental gradients across Europe and the eastern Mediterranean Basin. Specifically, we will evaluate the consequences of range expansions on the accumulation of deleterious vs. beneficial mutations in the context of genes and gene networks associated with responses to biotic and abiotic stressors in regions with contrasting climates. We will also estimate the potential for evolution in range-edge populations and their level of genomic and transcriptomic differentiation from ancestral populations. We will relate our results to phenotypic differentiation and fitness, addressing the question as to whether adaptive molecular variants are typically new mutations or arise from standing genetic variation. Finally, our project will assess the merit of active transplantation of genotypes among different geographical regions (i.e., genetic admixture) to facilitate new and rapid adaptive evolutionary responses to extremes in climatic tolerance. This will allow an evaluation of the effects on plant performance of potential heterosis and outbreeding depression (i.e., positive and negative genetic interactions) brought about by such admixture. Our project will establish at a genomic and transcriptomic level how plant populations respond to challenges from abiotic and biotic stressors brought about by climate change in the European context.
Let’s cross fingers!
A new edition of Pannell’s lab Away Days took place in the charming Alpine village of Mex, at the skirts of the Dents du Midi. Hikes in the mountains were interlaced by scientific updates and discussions, as well as by ‘armchair talks’ on the decisive moments of lab members’ scientific careers. The fast progress on Mercurialis genome sequencing is bringing new opportunities for population genomic studies in the genus, providing also comparative data for major crops from the Euphorbiaceae family (e.g. cassava). Experiments based on Mercurialis are also in full swing, with multiple hypotheses being tested on the evolutionary significance of male inflorescence architecture. Progress on metapopulation modelling is also bringing new insights on Mercurialis demographical history.
Enjoying outdoors Science!
This winter Away Days of Pannell’s lab at UNIL-DEE took place at Lac Taney. Among other research, updates on Mercurialis genome sequencing and the design of a new full-exome capture assay were discussed. In addition, new and exciting discoveries of new morphological traits in the species that may be relevant to understand the complex mating system in the species were provided by potdoctoral researcher Dr. Luis Santos-del-Blanco.
Pannell’s lab at Lac Taney
Under the title ‘Molecular adaptation in range expansions: predicting fitness of future plant communities’, members of the Mercurialis Genomics Network has just submitted a pre-proposal for the current call for projects of the ERA-CAPS (an ERA-NET from the seventh framework EU program for Coordinating Action in Plant Sciences). ERA-CAPS main objective is to promote sustainable collaboration in plant sciences through coordinating and funding excellent transnational research, including food security, adaptation to climate change, and biotic and abiotic stress response. The specific objectives of the project are to:
1) Evaluate the consequences of range expansions on the accumulation of deleterious vs. beneficial mutations, and thus on the process of local adaptation to new biotic and abiotic stress (e.g. herbivory, drought), in a gene network context.
2) Estimate the potential for evolution in colonization-front populations, their level of genomic and transcriptomic differentiation from ancestral populations, and the origin of adaptive molecular variants (new mutations vs. standing genetic variation), and relate this to phenotypic differentiation and phenotypic innovations.
3) Assess the merit of assisted migration (increase of genetic variation vs. outbreeding depression) to allow new adaptive responses in populations facing extremes in their climatic tolerance and evaluate, through environmental modelling, the fate of standing populations confronted with increasing pressure due to climate change.
These goals will be achieved by a combination of experimental evolution, genomic and quantitative genetic approaches using Mercurialis annua as model organism.
In March 2014, the Mercurialis Genomics Network has been launched, initially involving researchers from Switzerland, Spain, France, Germany, Poland, Belgium, Israel, and Italy. This network is born with the overarching goal of establishing an interaction platform for multidisciplinary research on Mercurialis species. The network will develop much needed medium- to long-term studies of molecular adaptation in Mercurialis, combining approaches and perspectives from different disciplines: molecular biology, evolutionary ecology, plant sciences and environmental modelling.