Climate warming and water primroses: germination responses of populations from two invaded ranges

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

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2016
Publication Date: 1/5/2017
Citation: Gillard, M., Grewell, B.J., Deleu, C., Thiebaut, G. 2016. Climate warming and water primroses: germination responses of populations from two invaded ranges. Aquatic Botany. 136(2017):155-163.

Interpretive Summary: Invasive water primroses from South America are characterized by their ability to quickly colonize aquatic environments through vegetative growth and dispersal. However, asexual reproduction may not be well suited to aquatic environments subjected to future environmental fluctuations. Future climate change may alter the reproductive strategies of water primroses and other aquatic plants, promoting greater sexual reproduction and survival of the species as an adaptation to climate conditions. Seed germination is a crucial step of plant reproduction, widely influenced by environmental conditions, including temperature. The aim of this study was to explore the germination capacity of the invasive species Ludwigia hexapetala and Ludwigia peploides subsp. montevidensis with increasing atmospheric temperature. Our study examined the responses of seeds from populations in two invaded ranges (California USA and Brittany, France). Their possible spread through seed dispersal and establishment is a rising concern, especially combined with the effect of climate warming on their future distribution. Germination of seeds collected in two invaded ranges was tested in controlled conditions at two air temperature regimes, 24°C/14°C and 27°C/17°C. We found that a 3°C warming accelerated the timing to germination of water primroses from California and France, but was not a driving factor in final germination percentage of the two taxa. However, seeds of L. hexapetala from California germinated 2-fold higher than seeds from France. No differences linked to the seed origin were observed within L. peploides populations. The germination rates of studied species were more than 80% for the three populations of L. hexapetala from California and for two populations of L. peploides from France. The variation observed between invaded ranges could be interpreted as an adjustment of the germination responses of water primroses populations to environmental characteristics.

Technical Abstract: Seed germination is a crucial step of plant reproduction, widely influenced by environmental conditions, including temperature. The aim of this study was to explore the germination capacity of the invasive species Ludwigia hexapetala and Ludwigia peploides subsp. montevidensis including populations from two invaded ranges. Their possible spread through seed dispersal and establishment is a rising concern, especially combined with the effect of climate warming on their future distribution. Germination of seeds collected in two invaded ranges was tested in controlled conditions at two air temperature regimes, 24°C/14°C and 27°C/17°C. We found that a 3°C warming accelerated the timing to germination of water primroses from California and France, but was not a driving factor in final germination percentage of the two taxa. However, seeds of L. hexapetala from California germinated 2-fold higher than seeds from France. No differences linked to the seed origin were observed within L. peploides populations. The germination rates of studied species were more than 80% for the three populations of L. hexapetala from California and for two populations of L. peploides from France. The variation observed between invaded ranges could be interpreted as an adjustment of the germination responses of water primroses populations to environmental characteristics.