2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

they developed the so called middle chamber epithelium as a third olfactory system.
The middle chamber epithelium of Pipidae is relatively well examined, due to the fact
that frogs of the Genus Xenopus are used as model organisms. On the contrary, the
recessus olfactorius has been only scarcely investigated, and many features like its
function or its phylogenetic relation to the middle chamber epithelium remain
unknown.
Lectin histochemistry was applied as one part of an extensive investigation of the
recessus olfactorius. With this technique, sugar residues of transverse sectioned
tissue of both frogs' noses were visualised. Analyses of resulting staining patterns of
Bombina orientalis' recessus olfactorius took place by comparison especially to
patterns of the middle chamber epithelium of Xenopus borealis, as well as to the
main olfactory and vomeronsal organs of both species. One aim is to discuss the
obtained results with respect to the possible homology of the recessus olfactorius
and the middle chamber epithelium. Further, the recessus olfactorius' nervous
connection to the brain is examined.
S�41 Philipp Brand M 627 / 12:00
The evolution of Odorant Receptors (ORs) in sibling species of orchid bees, as
revealed by RNA-Sequencing.
Authors: Philipp Brand 1 , Santiago Ramírez 2 , Florian Leese 1 , Ralph Tollrian 1 , Thomas
Eltz 1
Affiliation: 1 Department for Animal Ecology, Evolution, and Biodiversity, Ruhr-
Universität Bochum; 2 University of California-Berkeley, Berkeley
The insect Odorant Receptor (OR) gene-family encodes the ligand-gated ion channels
that mediate the perception of volatile chemicals, and therefore constitute the main
basis of odorant perception in the insect antennae. ORs are therefore crucially
important for foraging and mate detection in insects. In male orchid bees (Apidae:
Euglossini) olfaction is also used to locate sources of odoriferous chemicals, which are
harvested to concoct a complex, species-specific male perfume. This perfume is later
displayed at mating territories, presumably to attract conspecific females.
Recent electroantennographic comparisons of orchid bee antennae revealed speciesspecific
responses to certain perfume components. Therefore the detection or
attraction elicited by different odorants may be mediated via a species-specific set of
OR genes or differential expression of ORs in the antennae. In a first step to test this
hypothesis, we examined the antennal transcriptomes of males of two recently
diverged sibling species of orchid bees, Euglossa dilemma and Euglossa viridissima,
from southern Mexico. Non-normalized antennal mRNA from male bees was
sequenced on a single lane of an Illumina HiSeq 2000 sequencer. The de novo
assemblies of the transcriptomes revealed various ORs, most of which had orthologs
in both Euglossa species and in Apis mellifera. Ongoing analyses aim at identifying
candidate ORs for detailed expression studies and to identify genomic signatures of
diversifying selection. The results are important for a better understanding of orchid
bee OR evolution and the role of ORs in orchid bee speciation.
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