Abstract
Invasive plants are expanding their geographical distribution across new regions. Expansion modeling is crucial for geographic prioritization in management policies. However, the assumption of niche conservatism and the lack of information of the species physiological response to the environmental factors determining species presence may hinder predictions. In this study, we aimed to understand the expansion of the widely distributed plant Carpobrotus edulis in Europe. We contrasted introduced and native C. edulis ecological niches and explored the experimental response to temperature, a major determining factor for species distribution, of native and invasive individuals in terms of different biochemical markers. Niche analysis revealed an expansion of the introduced niche to occupy colder climates. Introduced and native individuals showed differential mechanisms facing low temperatures. Individuals from the native range showed an increased sensitivity to chilling, as reflected by photosynthetic pigment degradation, increased de-epoxidation of xanthophylls and the accumulation of the lipophilic antioxidant alpha-tocopherol. The found physiological differentiation towards an increased invasive chilling tolerance of invasive C. edulis individuals together with a high propagule pressure may explain the introduced climatic niche shift to colder climates observed, allowing the extensive expansion of this species in Europe.
Highlights
Despite invasive species constituting one of the main threats to global biodiversity, the key factors determining their success when colonizing extensive areas are still unknown (Simberloff et al, 2013)
Considering the European and native ranges, the distribution of C. edulis is constrained to annual mean temperatures of between 7 and 20◦C and annual precipitation ranging from 100 to 1500 mm (Fig. 1A)
It is known that changes in the pigment composition of light-harvesting complexes allow the reduction of absorbed light and the increase in energy dissipation through non-photochemical quenching via the xanthophylls, with the deepoxidation of violaxanthin to anteraxanthin and zeaxanthin preventing excess energy at the chloroplast (Demmig-Adams and Adams, 1996)
Summary
Despite invasive species constituting one of the main threats to global biodiversity, the key factors determining their success when colonizing extensive areas are still unknown (Simberloff et al, 2013). No single factor explains the species distribution limits and their expansion, but propagule pressure, environmental suitability and biotic relationships may have a role during species expansion across new territories out of their native geographical distribution (Willi and Van, 2019). Besides those factors, the study of invasive species expansion reinforced the importance of rapid evolutionary changes determining the invasive success (Bossdorf et al, 2005). The comparison of several functional traits of Acer pseudoplatanus growing in France (native) and New Zealand (invaded range) under different light regimes revealed higher plasticity and faster growth of invasive individuals (Shouman et al, 2017). SDM assumes that actual introduced and native range occurrences define the species’ response to environmental variables (Peterson, 2003), with no clue as to the species’ potential to respond to environmental conditions
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