Spatio-temporal patterns in pollination of deceptive Aristolochia rotunda L. (Aristolochiaceae).
Pollination success of highly specialised flowers is susceptible to fluctuations of the pollinator fauna. Mediterranean Aristolochia rotunda has deceptive trap flowers exhibiting a highly specialised pollination system. The sole pollinators are kleptoparasitic flies in search of food. This study investigates these pollinators on a spatio-temporal scale and the impact of weather conditions on their availability. Two potential strategies of the plants to cope with pollinator limitation, i.e. autonomous selfing and an increased floral life span, were tested. A total of 6156 flowers were investigated for entrapped pollinators in 10 Croatian populations. Availability of the main pollinator was correlated to meteorological data. Artificial pollination experiments were conducted and the floral life span was recorded in two populations according to pollinator availability. Trachysiphonella ruficeps (Chloropidae) was identified as dominant pollinator, along with less abundant species of Chloropidae, Ceratopogonidae and Milichiidae. Pollinator compositions varied among populations. Weather conditions 15-30 days before pollination had a significant effect on availability of the main pollinator. Flowers were not autonomously selfing, and the floral life span exhibited considerable plasticity depending on pollinator availability. A. rotunda flowers rely on insect pollen vectors. Plants are specialised on a guild of kleptoparasitic flies, rather than on a single species. Pollinator variability may result in differing selection pressures among populations. The availability/abundance of pollinators depends on weather conditions during their larval development. Flowers show a prolonged trapping flower stage that likely increases outcrossing success during periods of pollinator limitation.
['Oelschlägel|B|B|', 'von Tschirnhaus|M|M|', 'Nuss|M|M|', 'Nikolić|T|T|', 'Wanke|S|S|', 'Dötterl|S|S|', 'Neinhuis|C|C|']
D000818:Animals D030022:Aristolochia D004175:Diptera D035264:Flowers D005843:Geography D011058:Pollen D054817:Pollination D012098:Reproduction D062211:Spatio-Temporal Analysis D013045:Species Specificity D014887:Weather
Aristolochia rotunda floral life span Chloropidae pollinator variability autogamy deceptive pollination flower biology