Floral allocation at different altitudes in highly autogamous alpine Chaetanthera euphrasioides (Asteraceae) in the central Chilean Andes

Abstract

In the alpine life-zone, increasingly slower and unpredictable pollination at the higher altitudes predict an increase in floral investment in strongly outcrossing, pollenlimited biotically pollinated plant species, but not in autonomously self-pollinating species. Plant size, floral and above-ground vegetative biomass and individual capitulum biomass were studied in highly autogamous Chaetanthera euphrasioides (DC.) F. Meigen (Asteraceae) at 2,400 m a.s.l. and 3,300–3,400 m a.s.l. in the high Andes of central Chile. Contrary to prediction, altitude had a small positive effect on floral biomass investment and the anisometric relationship between floral investment, and plant size differed at the two altitudes. Individual capitulum size, however, was not affected by altitude. Plastic floral allocation and selection to increase seed production and ameliorate stronger inbreeding at the higher elevations are discussed as possible explanations for the small but unexpected altitudinal increase in floral allocation.