RENAULT, D. | bioRxiv Science

bioRxiv2025

Adaptive Strategies of the invasive aquatic plant, Ludwigia grandiflora subps. hexapetala: Contrasting Plasticity Between Aquatic and Terrestrial Morphotypes.

Biological invasion is the fifth biggest threat to biodiversity and ecosystem processes. Invasive species are able to colonise new environments rapidly due to their phenotypic plasticity. Ludwigia grandiflora subsp. hexapetala (Lgh), an aquatic invasive plant, invades various aquatic habitats, such as rivers, ponds, and more recently, especially in France, wet meadows. More recently, a terrestrial morphotype, emergent for half the year, has been identified. The behaviour of aquatic and terrestrial morphotypes in aquatic and terrestrial conditions was analysed through observations of morphological traits, and assays of metabolomics and phytohormones 14 and 28 days after the beginning of the experiment. The phenotypic plasticity was evaluated by calculating the relative distance plasticity index (RDPI) in response to environmental changes (terrestrial versus aquatic). RDPI were measured for morphological traits, metabolic and phytohormonal contents. Our results revealed that the terrestrial morphotype showed higher morphological trait values than the aquatic morphotype, independently of conditions, suggesting a pre-adaptation of Lgh to terrestrial habitats. The aquatic and terrestrial conditions shaped the Lgh metabolomic responses. However, the aquatic morphotype displayed higher phenotypic plasticity indexes than the terrestrial one. In addition, plasticity indexes evolved during the acclimatisation process, leading to increased RPDI values in most cases. The two morphotypes present distinct responses to aquatic and terrestrial conditions (especially in aquatic conditions for the terrestrial morphotype), highlighting the capacity of Lgh for invading new habitats due to its phenotypic plasticity, and a potential local adaptation. This study contributed to the understanding of how invasive species mobilise their phenotypic plasticity in new habitats, and the time required for local adaptation to occur.

plant biology↗

bioRxiv2020

Once upon a time in the south: local drivers of plant invasion in the harsh sub-Antarctic islands

AimHere, we aim to: (i) investigate the local effect of environmental and human-related factors on alien plant invasion in sub-Antarctic islands; (ii) explore the relationship between alien species features and their dependence on anthropogenic propagule pressure; and (iii) unravel key traits conferring invasiveness in the sub-Antarctic. LocationPossession Island, Crozet archipelago (French sub-Antarctic islands). TaxonNon-native vascular plants (Poaceae, Caryophyllaceae, Juncaceae). MethodsSingle-species distribution models were used to explore the effect of high-resolution topoclimatic and human-related variables on the occurrence of six of the most aggressive alien plants colonizing French sub-Antarctic islands. Furthermore, the interaction between alien species traits and their response to anthropogenic propagule pressure was analysed by means of a multi-species distribution model. This allowed identifying the features of species that were associated to low dependence on human-assisted introductions, and were thus potentially more invasive. ResultsWe observed two main invasion patterns: low-spread species strongly dependent on anthropogenic propagule pressure and high-spread species limited mainly by harsh climatic conditions. Differences in invasiveness across species mostly related to their residence time, life history and plant height, with older introductions, perennial and low-stature species being more invasive. Main conclusionsThe availability of high-resolution data improved our understanding of the role of environmental and human-related factors in driving alien species distribution on sub-Antarctic islands. At the same time, the identification of alien species features conferring invasiveness may help anticipating future problematic invasions.

ecology↗