Students
Current theses
Oleg Lewkowski
Franziska Pietschmann
Stephanie Weier
Former Diploma Students
Tina Flemming
Sophie Helbing
Colonies of eusocial insects consist of highly related individuals with frequent social contacts, which cooperate to ensure colony development. Unfortunately, such colonies are susceptible to parasitic infections and thus, effective mechanisms to handle the high infection risk are expected to occur. Therefore eusocial insects, like the bumblebee Bombus terrestris, evolved a social immune system. Social immunity comprises individual defenses (e.g. production of antimicrobial peptides) and group-level defenses (e.g. social fever in honeybees). In this study the impact of the social context (group size) in response to an infection will be determined. Therefore the gene expression between single or grouped bumblebees, which are either infected or not, is quantified by means of RNA-seq. Special emphasis will be given to immune responsive genes.
Anne Lüth
Kathleen Mönch
There are five honeybee species of the genus Apis in Borneo. One of them is the Asian giant honeybee Apis dorsata. The colonies build single combs which normally hang from a tree branch at heights of 20-40 m and often found in dense aggregations. Another fascinating characteristic of A. dorsata is the seasonal migration between alternate nesting sites and the returning depending on different blooming seasons. The queen is high polyandrous and mate with up to 90 drones over two or three mating flights. The mating takes place at special drone congregation areas (DCAs). Aggregations cause relatedness between the colonies, contrary to migration and mating at DCAs, whose effect should be increase the genetic variability.
I focus my study on population genetics of A. dorsata using microsatellite markers. So I want to investigate the relatedness between the colonies and examine for possible subpopulations. With drone samples from the DCAs the genotype of the queens can be reconstructed and genetic differences between the DCAs can be identified. Furthermore I am interested in questions of population ecology like the popularity between the DCAs and the number of colonies which use one DCA.
Astrid Mosemann
Juliane Puchert
Jeanny Richter
Elisabeth Weise
Honeybee population structure can be influenced by several factors – one of them is beekeeping practice. This differs between different regions of the world. In South Africa beekeeping practice typically combines swarm and migratory beekeeping. This leads to a continuous change of the composition of a beekeeper’s colonies and mixes populations from all over the country. Therefore highly diverse populations could artificially be created. A wild honeybee population gets in contact with a smaller number of bee populations in contrast.
To assess the influence of these different situations in commercial and wild bee populations on honeybee population structure I compare the population structure of a managed and a wild South African honeybee population. For this purpose I genotype drone samples of both populations using linked microsatellite markers. The genotypes will be used to estimate parameter of population structure like genetic diversity for both honeybee populations.
Christiane Hönicke
In spite of traffic regulation we all know traffic jams. Also ant colonies depend on a permanent traffic flow to guarantee the survival of the colony. In assumption that evolution has shaped the traffic – there should be a optimal adaptive solution on ant trails.
I study this in the ant Formica pratensis, the black-meadow ant. This species uses distinct trunk trails cleared from debris which prevent disturbances and facilitates the analysis.
The aim of this study is to analyse the collective movement of the ants on their natural trails.
Especially the relation between velocity, density, lane usage and contacts takes center point to detect the traffic rules behind the behaviour of the ants.
Daniel Schröter
Spider webs exhibit an enormous diversity in size, shape and usage of sticky threads. The orb web is the most famous and often regarded as the highest developed spider web type. My research is focused on the web building behaviour of a typical orb-weaving spider -- the wasp spider, Argiope bruennichi. It is one of the most striking, widespread and therefore well studied orb-web spider in Europe. In addition to its distinctive phenotype, they add specific web decorations between two adjacent radii (radii decoration or stabilimentum) and otherwise circular-like silk mats cover the hub (hub decoration).
Despite numerous explorations there is still an ongoing debate about the functions or adaptive values of these web decorations. I try to include physiological aspects in my research including the moulting events and the production of the egg sac building phase, two of the strongest interfering moments with regard to a spider life and also to web construction behaviour.
Eve Gerecke
The performance of spectacular mating flights is a behavioural characteristic common to all honeybee species (genus Apis). The differences of mating flight times of drones from different honeybee species are fundamental for the speciation process. Particularly in sympatric Apis species, the timing of mating flight is the basic behavioural mechanism of reproductive isolation shaped by natural selection.
I am interested in the identification of major quantitative trait loci QTLs which are in control of flight time patterns in honeybee drones. For this purpose, I observe the flight times of individually marked drones from a single Apis mellifera colony. After defining their phenotype - early vs. late flyers, I employ a bulk segregant analysis using microsatellite DNA markers, to identify potential genomic regions containing a QTL. The subsequent fine mapping of such genetic regions provides an indication of genes which are involved in the regulation of flight time of drones. Such can be considered as true speciation genes and are therefore of high interest for further evolutionary studies.
Theresa Toev
In contrast to bumblebee drones, which permanently leave the nest for mate-search, workers always return to the colony after foraging hence are central place foragers. Nothing, however, is known about the spatial and temporal dynamics of the drone populations.
Based on a large, temporarily distinct B. lapidarius samples I tested two hypothetical scenarios:
- high turnover resulting in distinct drone cohorts over time.
- no turnover but an extended mate search area of the drone population.
Christoph Eller
Mitochondrial DNA is normally suspected to be transmitted only by the oocyte. During fertilization of honey bee eggs multiple sperms are able to enter the Oocyte and bring in paternal mitochondrial DNA. The intention now is to examine what happens to this paternal mtDna. Is it diluted due to the number of cell divisions or is it degraded actively? These examinations will be carried out by Quantitative Real Time PCR techniques and hopefully provide information according to evolutionary processes concerning mitochondrial DNA.
Cornelia Geßner
Varroa destructor is an ectoparasitic mite that preferably reproduces on drone brood and a great threat to honeybees (Apis mellifera) causing colony losses of great extent worldwide. However, infested colonies have been reported to survive without chemical treatment against the mite, which implies a selection of resistance alleles in these populations. The purpose of this study is to identify candidate genes that mediate Varroa tolerance using Quantitative-trait-loci-(QTL)-mapping to shed light on a possible co-adaptation of host and parasite. The mapping is performed on haploid drone offspring from a cross between Varroa tolerant queens and susceptible drones allowing for very distinct phenotypes and excluding interaction of homologous alleles.
Marcel Medrano
Arrhenotokous parthenogenesis appears to be the dominant mode of sex determination within the Hymenoptera with Complementary Sex Determination (CSD) forming the underlying mechanism. Thereby the allelic constellation of an identified gene locus named csd leads to female development when heterozygous and to male development in the case of homozygous or hemizygous allelic composition as it occurs in unfertilized haploid eggs. But the molecular trait at DNA-(or protein) level which defines the essential allelic identity is still not known. In our investigation on an isolated Apis mellifera population we use csd-linked microsatellites to determine haplotypes representing the embedded allele. This allows haplotypes to be assigned to identical or distinct functional alleles which then can be compared in order to find the allele defining molecular characteristics.
Constanze Westphal
The wasp spider (Argiope bruennichi) probably is the most conspicuous orb weaving spider in Germany with its striking yellow and black markings on its abdomen. This spider species is not only famous for its coloration but for the silken decorations called "stabilimenta" which they often attach to their webs. However, the adaptive value of these decorations is still unclear. So in this study we investigate the drinking and grooming behavior of these spiders in relation to their decorations which seem to facilitate the water uptake and so help to balance the hygric status of these animals.