The evolution of attachment structures in two megadiverse insect lineages : Acercaria and Diptera
A detailed description of the morphology and ultrastructure of attachment devices is one of the major aims of the present thesis. In total 77 (incl. 18 outgroups) species are studied using a broad array of different techniques, with emphasis on high quality documentation. Another aim of this thesis is the reconstruction of the phylogenetic relationships of the acercarian suborders. A character set which allows a formal analysis of acercarian relationships independently of molecular data is provided. Combined with original studies a morphological data matrix of 118 characters of all body parts for 25 acercarian species is presented, evaluated and discussed. Based on the phylogenetic results, scenarios for the evolution of the acercarian attachment devices are discussed. Character evolution of pretarsal structures in Diptera was evaluated by mapping the observed character states onto an already existing phylogeny. The morphological changes that single attachment devices (arolia) underwent are discussed. The Interactions of plant surfaces and attachment devices are examined as well. The possible role the attachment ability might play in speciation is investigated in the pea aphid complex. Using traction force measurements it is tested how the different host specific varieties of pea aphids perform on host and non-host plants with very different surface topologies. It is shown how the waxy surface of some plants reduces the attachment ability.