The response of floral traits associated with pollinator attraction to environmental changes expected under anthropogenic climate change in high-altitude habitats

Authors: Brunet, Johanne; VAN ETTEN, MEGAN - Pennsylvania State University

Submitted to: International Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2019
Publication Date: 10/15/2019
Citation: Brunet, J., Van Etten, M. 2019. The response of floral traits associated with pollinator attraction to environmental changes expected under anthropogenic climate change in high-altitude habitats. International Journal of Plant Sciences. 180(9):954-964. https://doi.org/10.1086/705591.
DOI: https://doi.org/10.1086/705591

Interpretive Summary: In high-altitude habitats, plants have few new suitable habitats to colonize following environmental changes and must therefore rapidly adjust to their new environment. Phenotypic plasticity, or the ability of a genotype to express distinct phenotypes in different environments, may therefore serve as an important mode for rapid evolution to environmental changes in these high-altitude environments. Climate models predict an increase in temperature and in spring and early summer rainfall as a result of global warming in high-altitude environments. The environmental changes associated with global warming are likely to favor new phenotypes. The response of floral and plant traits to environmental changes expected under global warming in high-latitude habitats, will depend on whether a trait is phenotypically plastic in response to water availability and/or temperature, whether there exists heritable genetic variation for phenotypic plasticity within or among populations and finally, whether the trait itself is genetically variable, within or among populations. After examining these questions, a positive outcome of this study was that all of the traits examined had the potential to adjust to the new environmental conditions expected under global warming in high-altitude habitats. Phenotypic plasticity was prevalent and a rapid response to environmental changes via phenotypic plasticity was possible for most traits examined. The increase in temperature and precipitation in late spring and early summer expected under global warming in high-altitude habitats may even increase the reproductive potential of this plant species. Results from this study are important because they help determine the potential for plants to adapt to new environmental conditions, and particularly environmental changes expected under global warming. This information is important to policy makers, to scientists, and the general public interested in the implications of global warming to the flora and provide information as to the fate of plants under changing environmental conditions.

Technical Abstract: While climate change will affect all plant species, those in high-altitude habitats cannot move to a more suitable habitat and must therefore adjust to their new environment. To determine how floral and plant traits associated with pollinator attraction may potentially change in response to global warming, we examined whether these traits were phenotypically plastic, whether genetic variation existed for these traits to enable adaptation and whether phenotypic plasticity itself had a genetic basis. Climate models predict an increase in temperature and in spring and early summer rainfall in high-altitude habitats. Therefore, we grew plants from 17 families from each of three natural populations at two temperatures and two water regimes in the greenhouse. We measured floral display (number of inflorescences and flowers per inflorescence), flower size (sepal and spur lengths), flower color (hue, chroma, and reflectivity), and reward (nectar volume and concentration). We used linear mixed models to examine the effects of family, population, temperature and water and their interactions on the different traits. Most traits except chroma, hue, and nectar concentration were phenotypically plastic in response to water. Only flower size traits and number of inflorescences responded to temperature while the response of sepal length, reflectivity and flowers per inflorescence to water changed with temperature. Phenotypic plasticity could evolve for many traits and all traits differed among populations. In response to environmental changes predicted under global warming in high-altitude habitats, we expect plants to have more flowers per inflorescence, larger flowers with shorter spurs, and flowers that produce more nectar. Spur length, sepal length and number of flowers per inflorescence are predicted to vary among populations. Flower color (hue, chroma, or reflectivity) and number of inflorescences per plant are not predicted to change under global warming. inflorescence, larger flowers with shorter spurs, and flowers that produce more nectar. Spur length, sepal length and number of flowers per inflorescence are predicted to vary among populations. Flower color (hue, chroma, or reflectivity) and number of inflorescences per plant are not predicted to change under global warming.