Submitted to: Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/4/2012
Publication Date: 4/1/2012
Citation: Brunet, J., Larson-Rabin, Z. 2012. The response of flowering time to global warming in a high-altitude plant: the impact of genetics and the environment. Botany. 90(4):319-326. Interpretive Summary: Climate change as a result of global warming could have a serious impact on plant reproduction. The magnitude of such an impact may be most severe in alpine plants because they lack alternative suitable habitats to colonize. These plants can not grow higher than the mountain peaks and therefore must adapt to environmental changes in order to survive. For adaptation to occur, a trait must have a genetic basis. However, plants also have the ability to modify their phenotypes in different habitats without changing the genetic basis of a trait. This phenomenon, the range of phenotypic expression of a genotype in different habitats, is referred to as phenotypic plasticity. In this study, we examined how the environment and genetics affected bolting (formation of an inflorescence) and the timing of flowering (anthesis) in an alpine plant species, the Rocky Mountain columbine. We grew plants from seeds originally collected from plants in three natural populations that occurred at different altitudes and varied in temperature and water availability. We grew plants from different families in two greenhouse rooms, each set at a different temperature regime. Within each family, 3 to 4 individuals received low water (dry conditions) and 3-4 received high water (wet conditions). On each plant we measured bolting (formation of flowering stalk) and the first day a flower opened on a plant (anthesis). We examined the impact of population of origin, temperature, water availability and family on bolting and anthesis times. On average, plants from Colorado bolted and flowered earlier than plants from Utah, which flowered earlier than plants from Arizona. Plants from each population of origin had adapted to their environmental conditions. Families within each population differed significantly with respect to bolting and flowering time which indicated that these two traits have a genetic basis. Both temperature and water affected flowering time with plants growing under cooler or drier conditions taking longer to flower relative to plants in hotter or wetter conditions. These phenotypic responses to environmental changes were similar in all three populations and for most families within each population which suggested a fairly strong degree of phenotypic plasticity for these two traits. Our results indicate that this alpine plant species has the potential to adapt to environmental changes.
Technical Abstract: Climate change as a result of global warming may seriously affect plant reproduction. This is especially true for alpine plant species because they have few suitable alternative habitats to colonize. It is therefore important to determine the ability of high altitude plants to adapt to environmental changes. In this study, we examined whether time to bolting and anthesis in the Rocky Mountain columbine had a genetic basis and how temperature and water availability affected these traits. We grew plants from seeds originally collected in three natural populations that differed in latitude and water availability. In each of two rooms, one set at 25.5º C during the day and 10º C (68º F) at night (hot room) and the other room set at 20º C (68 ºF) during the day and 4.4º C (58º F) at night (cold room), we grew plants from 17 families per population. Three to 4 individuals per family received either 500 mL every 4 days (wet conditions) or 500 mL every 8 days (dry conditions). For each plant in the experiment, we measured the date of bolting (inflorescence formation) and the date when the first flower opened (anthesis). We subsequently scaled these dates relative to the first date of bolting or anthesis in the experiment. We used analyses of variance to examine the impact of population, water, temperature and family nested within population and their interactions on bolting and anthesis times. We observed significant differences among families within populations, suggesting a genetic basis to bolting and anthesis times. The significant differences among populations observed in the greenhouse suggested an adaptation to the different habitats. Plants in the Colorado population bolted and flowered earlier, followed by plants in the Utah population and lastly plants in the Arizona population. However, we also observed a strong impact of the environment on bolting and anthesis times. Plants grown under cooler or drier conditions took longer to flower (anthesis) relative to plants in hotter or wetter conditions. While both water availability and temperature affected anthesis, only water availability influenced bolting. These patterns were observed in all three populations and for most of the families within each population. There is a genetic basis to bolting and anthesis times in the Rocky Mountain columbine and these traits have been differentially selected in the three populations suggesting a potential for adaptation if the environment were to change. Moreover, we observed a range of phenotypic expression of the trait within families under different environmental conditions which suggest a strong degree of phenotypic plasticity.