Evolution of local adaptation in anthropogenic environment – ELOCANTH

Controlled crosses between metallicolous and non-metallicolous individuals have been performed to evidence the number of genes involved in metal tolerance and hyperaccumulation. Simultaneously, non-metallicolous individuals will be sown on a polluted soil in controlled conditions, and their progenies will be sown year after year, to observe selection at work. Then, a specific sequencing method will reveal the genomic regions that are chimically modified (methylation) by metallic stress, without modification of DNA sequence (epi-genetics).

Controlled crosses between metallicolous and non-metallicolous individuals have resulted in an F2 progeny, which have been tested for zinc tolerance. Preliminary results seem to show that local adaptation to polluted sites is genetically determined.

Evidence of metal influence on genetic and/or epigenetic mechanisms will allow better understanding of adaptation capacities of plants to metal pollution.

No scientific production yet.

Human activities can generate extremely modified environments in a short period of time, so that habitat change is among major drivers of the current evolution of biodiversity. For biological species, survival to anthropogenic habitat change can requires the adaptation to novel conditions, potentially in a reduced number of generations. This is well known for plants in metal-polluted habitats: all populations of the reduced number of metallophyte plant that colonized metal-polluted habitats acquired the ability to tolerate toxic metal concentration in soils. Some of them are moreover able to accumulate huge concentrations of metal in shoots. Metallophytes are living examples of successful adaptations to habitat change. They therefore represent fruitful models for the study of the evolutionary dynamics of adaptation. Additionnaly, hyperaccumulators can provide genetic resources for the engineering of either phytoremediation techniques, for the restoration of metal-polluted soils, or biofortification techniques, for the nutritional improvement of crops.
In this context, we are interested in the evolution of biological traits implicated in the local adaptation to metal polluted soils in two model Brassicaceae species: Noccaea caerulescens and Arabidopis halleri. In both species, significant phenotypic differentiations have been shown between metallicolous populations, on polluted soils, and non-metallicolous populations. Differences were observed in controlled conditions between geographically close populations. They suggested that metallicolous population locally adapted to metal-polluted soils. Interestingly, recent genomic results suggested that the colonization of metal-polluted soils was accompanied by the selection of similar molecular mechanisms in both species. Considering that the species are phylogenetically and ecologically distant, and have distinct mating systems, this was surprising.
In the submitted project, we propose to analyze the genetic architecture and mechanisms of local adaptation in both species. This could be done using intra-specific crosses among metallicolous and non-metallicolous genotypes to perform QTL analysis of vegetative and reproductive traits related to metal tolerance and hyperaccumulation. Considering that metal-polluted environments are generally highly heterogeneous, we further propose to analyze the genetics of phenotypic plasticity for studied traits. Moreover, considering that metal tolerance is commonly assumed to evolve rapidly, we propose to perform epigenetic analysis of metallicolous and non-metallicolous genotypes. Finally, to discuss causal relationships between the colonization of metal-polluted soils and the phenotypic divergence of populations, we propose to perform experimental evolution following experimental population on metal-polluted substrate.