|Van Etten, Megan|
Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2013
Publication Date: 9/4/2013
Publication URL: http://handle.nal.usda.gov/10113/57861
Citation: Van Etten, M.L., Brunet, J. 2013. The impact of global warming on floral traits that affect the selfing rate in a high-altitude plant. International Journal of Plant Science. 174(8):1099-1108.
Interpretive Summary: Changes in the abiotic environment, such as those associated with global warming, can influence plant mating systems through changes in floral traits that affect selfing. Plant mating system is quantified as the proportion of offspring produced via self-fertilization. An increase in the selfing rate can negatively affect plant fitness and crop yield if selfed progenies are less successful than outcrossed progenies. Many insect-pollinated crops such as canola, alfalfa, the majority of fruits and many vegetables rely on pollinators and pollen from other plants (outcross) for successful seed production. Global warming may therefore negatively impact yield of these crops via its impact on floral traits that affect plant mating. It is therefore important to determine the impact of global warming on floral traits known to affect the selfing rate. Climate changes expected under global warming include changes in temperature and water availability. We found that herkogamy, dichogamy and total flower number, the three floral traits known to influence the selfing rate, were all affected by changes in water or temperature. Herkogamy represents the separation distance between the male (anther) and female (stigma) parts of the flower and is known to influence the level of within flower selfing (autogamy). Dichogamy refers to the temporal separation between the expression of male and female functions within a flower and can affect both within and among flower selfing (geitonogamy). Both a larger total flower number per plant and lower dichogamy increased geitonogamy by increasing the probability of transfer among male- and female-phase flowers within a plant. Based on our results, we predicted an increase in selfing rate as a plastic response to global warming with a negative impact on plant reproduction and survival. Our results emphasize the importance of considering the impact of global warming on plant mating system as it can negatively affect the yield of many insect-pollinated crops. Plant breeders and farmers should be made aware that changes in temperature and water availability associated with global warming can affect floral traits and the selfing rate of a crop with potential negative impact on crop yield.
Technical Abstract: Changes in the abiotic environment, as those expected under global warming, can influence plant mating systems through changes in floral traits that affect selfing. Herkogamy (spatial separation of male and female functions within a flower), dichogamy (temporal separation) and total flower number affect within (autogamy) and/or among flower selfing (geitonogamy). We grew plants from 17 families from each of three natural populations of Aquilegia coerulea at two temperature and two water treatments to test how global warming may affect herkogamy, dichogamy and total flower number and examined the consequences of these floral changes on selfing rate. In the high-altitude habitats in which this species grows, global warming is expected to increase both temperature and spring precipitation in the form of rain. Herkogamy, dichogamy and total flower number were all phenotypically plastic in response to changes in water availability or temperature. Genetic variation was detected within and/or among populations in these traits. Total flower number has a strong impact on selfing rate of A. coerulea populations and affects the level of geitonogamous selfing, and water has a greater impact on total flower number relative to temperature. We predicted greater flower number as a plastic response to global warming in this plant species and greater selfing rate resulting from an increase in the level of geitonogamous selfing. This plastic response to global warming will have negative impacts on this plant species where inbreeding depression is high. Selection may then act to reduce floral display and selfing rate but there will be a balance between the negative impact of inbreeding depression and the advantage provided by large floral displays in attracting pollinators.