Abstracts - Deutsche Zoologische Gesellschaft

Evolutionary Biology Symposium 43O EB.10 (Sa) - ENPhysiology of Zugunruhe in passerines caught at a stop-over site during springmigrationWolfgang Goymann 1 , Leonida Fusani 21Abteilung Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, Seewiesen; 2 Departmentof Biology and Evolution, Universita di Ferrara, ItalyMany day-active birds become active in the night during migration. The pineal gland and its hormonemelatonin are major components of the circadian system and hence possibly involved in thecontrol of the change in activity during migration. In captivity, birds show decreased levels of melatoninduring periods when they show Zugunruhe (migratory restlessness), but a causal relationshipbetween Zugunruhe and melatonin has not been established so far. In this study, we caught free-livinggarden warblers, whinchats and whitethroats on a stop-over site and kept them over-night in registrationcloth-cages to investigate factors related to Zugunruhe. Birds with a high fat score showedmore Zugunruhe than birds with a low fat score. Also, nocturnal levels of melatonin were negativelyrelated to Zugunruhe, i.e. birds showing high levels of nocturnal activity expressed lower levels ofmelatonin. In addition, melatonin levels were negatively related to corticosterone concentrations(another hormone suspected to be involved in the control of migration). However, we did not finda causal relationship between Zugunruhe and melatonin, as garden warblers treated with melatonindid not show different levels of Zugunruhe than controls. Because the fat score was the main predictorof Zugunruhe we are currently manipulating leptin – a hormone produced by the fat cells – andhope to present these additional results during the meeting.O EB.11 (Sa) - ENComplementary sex determination and inbreeding avoidance in the parasitic waspHabrobracon brevicornisAnne C. Weeda, Andra Thiel, Thomas S. HoffmeisterUniversität BremenIn species with single-locus complementary sex determination (sl-CSD), sex is determined by multiplealleles at a single locus. In the haplodiploid Hymenoptera, sl‐CSD results in females, if individualsare heterozygous (2n) at the sex locus, and in males, if they are hemi- (n) or homozygous (2n).Diploid males originate from matched matings, i.e. if a female wasp mates with a male carrying asex allele matching one of hers. They are sterile and, additionally to having zero fitness, accrue costson females they mate with. As a consequence of matched matings, parasitic wasps with sl-CSD, suchas Habrobracon brevicornis, rapidly show effects of inbreeding depression in small populations.In the F2-generation a huge male bias occurred already and more than 70 % of all inbreeding-linesbecame extinct in F3. In nature, this wasp produces clusters of eggs when parasitizing host insectsand thus, there is a large potential for inbreeding through sib-matings. An obvious question is howH. brevicornis avoids the associated costs. Our investigation focussed on three different potentialmechanisms of inbreeding avoidance. 1) Males and females may emerge asynchronously and maynot meet on the natal patch due to immediate dispersal. 2) Females may reject mating attempts earlyin their life and thus, before dispersal. 3) Females may employ kin-recognition to reject brothers asmating partners. Additionally, we tested whether females are able to discriminate against diploidmales.