Variation in germination capacity and seedling growth of water primroses in contrasting climates from two invaded continental ranges

Authors: GILLARD, MORGANE - University Of Rennes, France; Grewell, Brenda; Futrell, Caryn; DELEU, CAROLE - University Of Rennes, France; THIEBAUT, GABRIELLE - University Of Rennes, France

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/6/2017
Publication Date: 2/20/2018
Citation: Gillard, M., Grewell, B.J., Futrell, C.J., Deleu, C., Thiebaut, G. 2018. Variation in germination capacity and seedling growth of water primroses in contrasting climates from two invaded continental ranges. Meeting Abstract. 15th International Symposium on Aquatic Plants, Queenstown, New Zealand, proceedings.

Interpretive Summary: Aquatic ecosystems are vulnerable to biological invasions, and will also be strongly impacted by climate change. Understanding the colonization dynamics of aquatic invasive plant species is of high importance for preservation of native biodiversity. Many aquatic invasive plants rely on clonal reproduction to spread, but mixed reproductive modes are common. A shift of resource allocation to sexual reproduction is an advantage for populations to regenerate in changing environmental conditions. Thus, under future climate change, these species may favor a sexual reproductive mode. The aim of this study was to test the germination capacity and the seedling growth of two Ludwigia species invasive in Europe and in the USA, under contrasted climates. We performed a reciprocal transplant of seeds of Ludwigia hexapetala and L. peploides from two invasive ranges into experimental gardens characterized by oceanic and Mediterranean climates. Our results showed that higher temperatures increased or maintained germination rates and velocity, decreased survivorship of germinants, but increased their production of biomass. The origin of the seeds had low impact on L. hexapetala responses to temperature, but greatly influenced those of L. peploides. The invasiveness of water primroses in ranges with oceanic climates might increase with temperature rise due to increased sexual reproduction. The recruitment from seed banks by these species should be considered by managers to improve the conservation of native aquatic and wetland plant species.

Technical Abstract: Aquatic ecosystems are vulnerable to biological invasions, and will also be strongly impacted by climate change. Understanding the colonization dynamics of aquatic invasive plant species is of high importance for preservation of native biodiversity. Many aquatic invasive plants rely on clonal reproduction to spread, but mixed reproductive modes are common. A shift of resource allocation to sexual reproduction is an advantage for populations to regenerate in changing environmental conditions. Thus, under future climate change, these species may favor a sexual reproductive mode. The aim of this study was to test the germination capacity and the seedling growth of two Ludwigia species invasive in Europe and in the USA, under contrasted climates. We performed a reciprocal transplant of seeds of Ludwigia hexapetala and L. peploides from two invasive ranges into experimental gardens characterized by oceanic and Mediterranean climates. Our results showed that higher temperatures increased or maintained germination rates and velocity, decreased survivorship of germinants, but increased their production of biomass. The origin of the seeds had low impact on L. hexapetala responses to temperature, but greatly influenced those of L. peploides. The invasiveness of water primroses in ranges with oceanic climates might increase with temperature rise due to increased sexual reproduction. The recruitment from seed banks by these species should be considered by managers to improve the conservation of native aquatic and wetland plant species.