Genomic and functional approaches to explore the role of the environment in the adaptation and diversification of invasive aquatic plants

Biological invasions represent one of the leading causes of biodiversity loss and related ecosystem services, and climate change is likely to exacerbate the situation. Freshwater ecosystems are particularly susceptible to them due to their overall inadequate state of conservation as well as the difficulty of preventing and controlling the establishment of such invasive species. In these habitats, invasive macrophytes can reach a high abundance and develop monospecific populations through vegetative reproduction. Thus, it is crucial to identify traits and characteristics responsible for macrophytes’ invasiveness to efficiently manage current and future invasions. Invasive macrophytes often exhibit low genetic diversity during founding events and reproduce almost exclusively vegetatively. However, they still manage to adapt to novel environments through high levels of phenotypic plasticity, which is the ability of a genotype to produce different phenotypes in response to distinct environmental conditions. Increasing evidence suggests that epigenetic mechanisms, altering gene expression without changing its sequence, may underlie adaptive plasticity and contribute to plant adaptation, providing an alternative source of phenotypic and therefore functional diversity. However, the relationship between epigenetics and invasion is still poorly understood. In addition, it remains unclear whether traits associated with invasiveness in macrophytes are already present in native populations or evolved after introduction. Another important driver of plant traits and responses is genome size, however, we still know little about its importance to plant tolerance of environmental stressors. This project aims to investigate traits and mechanisms related to the adaptation and evolution of invasive macrophytes and focuses on two invasive macrophytes in Europe, Elodea nuttallii and Pistia stratiotes, and a native one, Trapa natans, as useful study models. Sampling will be carried out in various aquatic environments in Italy and in Europe and, to perform a confrontation analysis between the native and invasive range of the target species, in Brazil and Canada. The research will employ an approach based on functional traits, particularly those related to the leaf economics spectrum, as leaves are good predictors of plant performance. They will be combined with genetic and epigenetic variation analysis and genome size analysis, at both interspecific and intraspecific levels, and the habitat characterization through the measurement of the main environmental parameters. Joining functional and genomic approaches for characterizing invasive macrophytes across geographic areas can offer cross-feedback for a better understanding of the mechanisms behind the establishment and spread of invasive plants, as well as their competitive abilities in terms of functional traits and consequently support the development of effective management strategies and the protection of natural habitat biodiversity.