Format: ORAL

Leonardo Galetto1, Carolina Torres1

1 Departamento de Diversidad Biológica y Ecología, Universidad Nacional de Córdoba and CONICET, Argentina.

Pollinators are linked with plant reproduction and with evolutionary diversification of some clades of angiosperms. Modifications in floral form and function can suggest the best match with different pollinator functional groups implying a positive interaction in reproductive terms. Acanthaceae includes species with diverse floral sizes, shapes and colours that are visited by different pollinators. Previous studies analyzing different floral shapes (floral syndromes) and nectar in Acanthaceae indicated stronger relationships with floral shapes and nectar sugar composition or concentration rather than with phylogenetic trends. Nevertheless, some anatomical nectary particularities may restrict the expression of nectar traits in some groups (clades or genera) although the occurrence of floral form diversification within them. Moreover, nectar secretion patterns may be related with the preferences and needs of different pollinator groups. Thus, the variations in nectary and nectar traits in Acanthaceae may be shaped by a combination of the preferences of the main plant-pollinator interactions (functional or ecological) and/or by the basic anatomy and developmental constraints (phylogenetical) of the flower present in some clades or genus within this family. In consequence, complex trends between nectar and nectary traits could be analyzed using the hypothesis of pollination syndromes but also considering the most accepted hypothetical phylogeny of the family. If nectar and nectary traits are linked with pollinator preferences, associations between floral traits and different groups of pollinators will be stronger than the evolutionary trends within different clades. Species from major clades of Acanthaceae are used to test this hypothesis and predictions. Original data for anatomical features and nectar traits 20 species distributed among different phylogenetic clades were analyzed. Moreover, a data set from the literature of nectar traits for 100 species were obtained to present a better picture for the family linking developmental, ecological, and evolutionary trends.