Phenotypic trait differences between Iris pseudacorus in native and introduced ranges support greater capacity of invasive populations to withstand sea level rise

Authors: Grewell, Brenda; GALLEGO-TEVAR, BLANCA - University Of Seville; BARCENAS-MORENO, GAEL - University Of Seville; WHITCRAFT, CHRISTINE - California State University; THORNE, KAREN - Us Geological Survey (USGS); BUFFINGTON, KEVIN - Us Geological Survey (USGS); CASTILLO, JESÚS - University Of Seville

Submitted to: Diversity and Distributions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2023
Publication Date: 5/9/2023
Citation: Grewell, B.J., Gallego-Tevar, B., Barcenas-Moreno, G., Whitcraft, C.R., Thorne, K.M., Buffington, K.J., Castillo, J.M. 2023. Phenotypic trait differences between Iris pseudacorus in native and introduced ranges support greater capacity of invasive populations to withstand sea level rise. Diversity and Distributions. 29(7):834-848. https://doi.org/10.1111/ddi.13694.
DOI: https://doi.org/10.1111/ddi.13694

Interpretive Summary: Intertidal vegetation in coastal wetland ecosystems is increasingly vulnerable to unprecedented rates of climate change, sea level rise, and biological invasions that compromise diversity and critical ecosystem services provided by wetlands. This vegetation also prevents shoreline erosion, decreases flood risks, and sequesters carbon at high rates. These ecologically important plant communities have been invaded by alien species, including yellow flag iris. It is important to improve understanding of the stress physiological stress tolerances and fitness of these species in both their native and naturalized ranges to improve understanding of their ability to thrive under a broad spectrum of conditions. Tidal wetlands are highly impacted by climate change, and by the invasion of alien plant species that are being exposed to salinity changes and longer inundation periods resulting from sea level rise. To explore the capacity for the invasion of I. pseudacorus to be sustained with sea level rise, we initiated an intercontinental study along estuarine gradients in the invaded North American range (San Francisco Bay-Delta Estuary; California, USA) and the native European range (Guadalquivir River Estuary; Andalusia, Spain). We compared 15 morphological, biochemical, and reproductive plant traits within populations in both ranges to determine if specific functional traits can predict invasion success, and if environmental factors explain observed phenotypic differences. Results revealed that alien I. pseudacorus plants in the introduced range were more robust than plants in the native range. The vigor of the invasive plants was reflected by expression of higher specific leaf area and leaf water content, fewer senescent leaves per leaf fan, greater seed production, and more carbohydrate storage reserves in rhizomes. Invasive plants in California were less affected by increasing salinity, deeper water, and inundation along the estuarine gradient than those in the native range. Functional trait differences suggest mature populations of invasive I. pseudacorus have greater adapted capacity to adjust to environmental stresses induced by rising sea level than those in the native range. Knowledge of these trait responses can be applied to improve risk assessments in invaded estuaries, and to achieve climate-adapted conservation goals for conservation of the species in its native range.

Technical Abstract: Tidal wetlands are highly impacted by climate change, and by the invasion of alien plant species that are being exposed to salinity changes and longer inundation periods resulting from sea level rise. To explore the capacity for the invasion of I. pseudacorus to be sustained with sea level rise, we initiated an intercontinental study along estuarine gradients in the invaded North American range (San Francisco Bay-Delta Estuary; California, USA) and the native European range (Guadalquivir River Estuary; Andalusia, Spain). We compared 15 morphological, biochemical, and reproductive plant traits within populations in both ranges to determine if specific functional traits can predict invasion success, and if environmental factors explain observed phenotypic differences. Results revealed that alien I. pseudacorus plants in the introduced range were more robust than plants in the native range. The vigor of the invasive plants was reflected by expression of higher specific leaf area and leaf water content, fewer senescent leaves per leaf fan, greater seed production, and more carbohydrate storage reserves in rhizomes. Invasive plants in California were less affected by increasing salinity, deeper water, and inundation along the estuarine gradient than those in the native range. Functional trait differences suggest mature populations of invasive I. pseudacorus have greater adapted capacity to adjust to environmental stresses induced by rising sea level than those in the native range. Knowledge of these trait responses can be applied to improve risk assessments in invaded estuaries, and to achieve climate-adapted conservation goals for conservation of the species in its native range.