| In this project I tackled some of the unanswered questions regarding morphological and behavioural mimicry in hoverflies (Diptera: Syrphidae), using novel approaches.; First, I tested the possible role of invertebrate predators, specifically dragonflies, in the evolution of mimicry in hover flies. While dragonflies showed a significant tendency to attack small-sized prey compared to large-sized prey types, they did not seem to avoid the wasp-like colours and patterns of mimetic hover flies and attacked both mimics and non-mimetic prey types, of the same size, at a similar rate.; Second, a test of the 'competitive mimicry' hypothesis is performed. The basic tenet of this hypothesis is that mimetic hover flies benefit from their similarity to predatory yellow jackets by an improved access to resources since other pollinators avoid visiting flowers that they occupy. Pollinators were more likely to visit unoccupied flowers compared to flowers occupied with either natural or artificial specimens. However, pollinators did not show reduced visits to flowers pinned with specimens bearing wasp-like colours compared to flowers occupied by same-sized specimens that were non-mimetic.; Third, we used neural network to objectively assess the degree of similarity between hover fly images and their wasp models. Furthermore, using available data on pigeon's classification of hover fly images and also genetic algorithms along with neural network, we identified a reduced set of characteristics that birds may have used to rank the similarity hover fly images to wasps and flies.; Finally, in a behavioural study, I quantitatively compared the sounds produced by species of hymenopteran models and mimetic hover flies, when they were artificially attacked. Although I found some similarity in the buzzing sounds produced by bumble bees and their hover fly mimic, E. flavipes , I did not observe this similarity between the other two hymenoptera models (wasps and honeybees) and their presumed mimics. Moreover, all of the tested mimetic hover flies buzzed similarly to one another, independent of the model they resemble. The "buzzing behaviour" was not observed in the tested yellow jacket wasps. However, all of the tested hoverflies, bumblebees and honeybees emitted a distinctive and quantifiable "buzz" when probed. |
