Understanding The Relationship Between Physiology And Fruit Set In Clarkia Unguiculata And Clarkia Exilis

Plants are under constant risk of dessication. How plants deal with this risk may be influenced by or influence their mating system. Because of this, we are exploring whether selfing plants differ from outcrossing plants in regards to how they cope with their habitats. In Clarkia, endemic to the western United States, previous work has shown different physiological rates between the selfing (self pollinating) species Clarkia exilis and the outcrossing (have pollinators) close relative Clarkia unguiculata such as a higher photosynthetic rate in the selfers. Additionally, selfers go through their life cycle at an accelerated rate compared to their outcrossing sister taxa, which flower later on in the season. Consequently, outcrossing plants experience lower water availability that could negatively effect reproductive fitness. We examine how efficient C. exilis and C. unguiculata are at using water (Water use efficiency, WUE) and correlate this to a component of fitness, fruit set. With this study, we predict to find that selfing plants have lower WUE than their outcrossing sister taxa.  Furthermore, we should see a positive correlation between WUE (ratio between photosynthetic rate and transpiration rate) and fruit set (number of fruits produced divided by number of flowers on the plant) in the outcrossing species because of the lower availability of water present during flowering. With more water earlier in the season however, we may see no relationship or even perhaps a negative correlation between WUE and fruit set in the selfing species.