|2013 – present||PhD studies in Evolutionary Biology. Institute of Systematic Botany, University of Zurich. Topic: “Pollinator mediated selection and local adaptation in a generalized pollination system”.|
|2011 – 2013||MSc in Systematics and Evolution. Institute of Systematic Botany, University of Zurich. Topic: “Mechanisms of Pollinator Attraction in Brassica rapa flowers”|
|2007 – 2011||BSc in Biology. University of Zurich.|
Local adaptation to tritrophic interactions
Plant-animal interactions impose selection on plant traits and cause local adaptation of plant populations. Flower-dwelling predators like crab spiders can harm plants by hunting pollinators, or benefit them by feeding on herbivores. The effect of crab spiders on plant fitness may therefore depend on direct plant-animal interactions, causing complex selection patterns. The crab spider Thomisus onustus is an abundant predator on inflorescences in lowland populations of the alpine herb Biscutella laevigata, but absent in highland populations. We will use this system to investigate the effect of crab spiders on floral trait evolution by a combination of common garden experiments and behavioural assays.
The effect of pollinators and herbivores on selection for floral signals
Through their preferences for floral cues, pollinators, but also herbivores, can mediate selection on a variety of plant traits. Selection by mutualists and antagonists may not be independent from each other, however, as the selection on a trait through one interaction can depend on the presence or intensity of another interaction. Bumble bees (Bombus terrestris) and cabbage butterflies (Pieris brassicae) are both pollinators of Brassica rapa, but cabbage butterflies also use B. rapa as a host plant for their caterpillars. In a cage experiment we will analyse the patterns of selection on floral traits in Brassica rapa plants exposed to a) bumble bees, b) cabbage butterflies, and c) bumble bees and cabbage butterflies together.
Maintenance of honest signalling
Most pollinators visit plants for rewards and would therefore gain an advantage from discriminating between conspecific plant individuals based on the quality and quantity of offered rewards. This requires predicting the reward state through honest floral signals that are correlated with reward amount. In this study we will investigate the relative importance of honest signals for pollinator attraction and the mechanisms maintaining signal honesty by using a combination of behavioural assays, selection experiments and mathematical modelling.
Aguilar-Rodriguez PA, MacSwiney MC, Kromer T, Garcia-Franco JG, Knauer A, Kessler M (2014) First record of bat-pollination in the species-rich genus Tillandsia (Bromeliaceae). Annals of Botany 113 (6):1047-1055. doi:10.1093/aob/mcu031
Knauer AC, Schiestl FP (2015) Bees use honest floral signals as indicators of reward when visiting flowers. Ecology Letters 18 (2):135-143. doi:10.1111/ele.12386
Knauer AC, Schiestl FP (2016) The effect of pollinators and herbivores on selection for floral signals: a case study in Brassica rapa. Evolutionary Ecology. doi:10.1007/s10682-016-9878-8