Can pollinator-mediated selection explain the intrapopulation variation in morphological traits in Epidendrum fulgens (Orchidaceae)?

Abstract

In studies on the biology of pollination, the flower has traditionally been the focus of investigations, however, inflorescence size, number of inflorescences and plant height are also considered important traits to determine the attractiveness of plants. Furthermore, even studies focusing on the flower have a bias, since few investigate floral shape and color. Pollinator-mediated selection has been widely studied, and pollinators are often considered the main selective agents that drive plant diversification, especially in deceptive species. Indeed, floral variation in deceptive species may be due to lack of selection pressures on floral traits or to variation in selection of different traits at different flowering periods, this hypothesis is called fluctuating selection. This research proposal has two core objectives: to investigate if pollinator-mediated selection is present in two populations of Epidendrum fulgens, a deceptive orchid species pollinated by several species of butterflies and which has an intrapopulation variation in floral coloration and morphology; and to examine if pollinator-mediated selection patterns change over different flowering periods, consistent with the fluctuating selection hypothesis. This project intend to test whether there is a correlation between reproductive success of the plants and six morphological traits (plant height, number of inflorescences, total number of flowers, number of flowers per inflorescence, shape of floral pieces and floral color), if there is pollinator-mediated natural selection involved in the correlations and if the selection along of two distinct flowering periods is compatible with the fluctuating selection hypothesis. For this, we will analyze data collected over two years during the candidate's master's program, with the help of her co-supervisor, Dr. Giovanni Scopece, who is a specialist in pollinator-mediated phenotypic selection analysis. (AU)