Meeting Abstract
69-2 Saturday, Jan. 5 13:45 – 14:00 The beetles with the protrusible tongue: Integration of form, function, and ecology in the predatory rove beetles Stenus spp. BETZ, O*; HEETHOFF, M; GARAMSZEGI, LZ; KOERNER, L; University of Tübingen, Germany; Technical University of Darmstadt, Germany; Estación Biológica de Doñana-CSIC, Spain; University of Tübingen, Germany; Frau oliver.betz@uni-tuebingen.de https://uni-tuebingen.de/en/faculties/faculty-of-science/departments/biology/institutes/evolutionecology/groups/evolutionary-biology-of-invertebrates/about-us/
The rove beetle genus Stenus has experienced a tremendous radiation, comprising > 3000 species widely distributed throughout the world. Its evolutionary success can be partly attributed to specific morphological features, two of which will be in the focus of this contribution: (1) the labium, or lower lip, is modified into a prey-capture apparatus that can be rapidly protruded a long distance out of the body to stick onto elusive and quick-moving prey such as springtails; (2) proceeding from a phylogenetically antecedent condition with slender tarsi, the tarsi of most species are widened and distinctly bilobed. Based on studies on the functional morphology and ultrastructure of these two organs, comparative experiments on their performance capacity were carried out to elucidate their adaptive value. The direct relationship between morphology, behavior and performance was studied by using phylogenetic generalized least squares and a molecular phylogeny generated from mitochondrial cytochrome c oxidase I partial sequences. The prey-capture success of the labium compared to that of the mandibles suggest that the specialized labial apparatus of Stenus beetles provides an ecological advantage in that it permits these predators, in spite of the limited reaction ability and agility of many Stenus species, to catch prey that are capable of sudden and rapid escape behaviour. Interspecific differences in the adhesive forces generated during the predatory attack entail significant differences in the prey-capture success. In terms of the tarsi, the main selective demands driving their widening in several lineages have probably come from their firm attachment to smooth plant surfaces.
