Mapping the genome of the bumblebee Bombus terrestris with microsatellite loci
Final Report Abstract
The main achievement of this project has been the establishment of a large number of genetic markers for the bumblebee Bombus terrestris for which sequence information is available (microsatellites). Subsets of these markers have been tested for other species in the genus Bombus. The microsatellite markers can now be used in a wide range of population genetic studies, including topics related to sexual selection, population structures, genetic variability and diversity, conservation, monitoring of linked phenotypes. The large number of markers allowed for the construction of a high resolution genetic linkage map. In total 18 linkage groups could be identified, representing all 18 haploid chromosomes. The average marker distance of about 4cM provides an excellent tool to dissect the genomic architecture of Bombus terrestris and provides the basis for mapping quantitative trait loci. The detailed genetic map in combination with the estimated genome size of Bombus terrestris (250Mb) provided an exact estimate for the recombination rate of more than 8 cM/Mb. This rate, although not as high as in the honeybee (15.7 cM/Mb), is significantly higher than in other organisms like Drosophila spec. or the male haploid parasitic wasp Nasonia vitripennis. A high genomic recombination rate is therefore not linked to male haploidy, but either a specific character of the lineage of Apidae (bees), or may be linked to to the social life history of the honeybees and bumblebees (e.g in response to pathogens). A major goal of this study was the comparison of the genome structure of Bombus terrestris with Apis mellifera. Based on homologous loci, the genetic maps of both species could be compared side by side and revealed an extremely high degree of conservation of the genome structure. A high proportion is conserved in synteny (same marker order) or with rearrangements on the same chromosome. Interchromosomal rearrangements were the exception. This result is surprising in the light of the very high recombination rate in both species. Given the long phylogenetic separation (100 mya) a much higher degree of genomic reorganization was to be expected. For example genome and chromosome evolution among closely related Drosophila species or among vertebrates are characterised by many interchromosomal rearrangements with frequent reshuffling of chromosomal segments, in spite of a much shorter phylogenetic distance among the species and much lower genomic recombination rate. Possible explanations for this high degree of conservation of genome structure in the Apidae remain untested and might nonexclusively include a lower number of transposable elements, haplodiploidy or even sociality itself. These results will open up new avenues for comparative genomics and genetic studies. In the near future more comprehensive data, especially due to sequencing of more genomes will further complete our knowledge about the genome and chromosome evolution and its importance for sociality.
Publications
- (2009): A tool for phylogenetic analysis: Cross‐species amplification of microsatellite loci in Apidae. 102. Annual Meeting of Deutsche Zoologische Gesellschaft ‐ DZG (Regensburg, Germany ‐ September 2009)
Müller M, Stolle E, Kraus FB, Moritz RFA
- (2009): A tool for phylogenetic analysis: Cross‐species amplification of microsatellite loci in Apidae. New Molecular Tools Workshop, Bern, Switzerland (05/2009)
Müller M, Stolle E, Kraus FB, Moritz RFA
- (2009): Microsatellites in three hymenopteran genomes. 56. Jahrestagung der Arbeitsgemeinschaft der Bieneninstitute, Schwerin 2009, March 24th ‐ 26th
Stolle E, Schmid‐Hempel P, Schmid‐Hempel R, Lehrach H, Moritz RFA
- (2009): Novel microsatellite DNA loci for Bombus terrestris (Linnaeus, 1758). Molecular Ecology Resources (2009) 9, 1345–1352
Stolle E, Rohde M, Vautrin D, Solignac M, Schmid‐Hempel P, Schmid‐Hempel R, Moritz RFA
- (2010): A 2nd generation genetic map of the bumblebee Bombus terrestris. 15th PhD Meeting of Evolutionary Biology of the DZG (Freiburg i.B., Germany ‐ April 2010)
Stolle E, Wilfert P, Schmid‐Hempel R, Schmid‐Hempel P, Reinhardt R, Kube M, Moritz RFA
- (2010): A 2nd generation genetic map of the bumblebee, Bombus terrestris, and comparison with the Apis mellifera genome. XVI Congress of the International Union for the Study of Social Insects IUSSI, Copenhagen, 8‐14 August 2010
Stolle E, Wilfert P, Schmid‐Hempel R, Schmid‐Hempel P, Reinhardt R, Kube M, Moritz RFA
- (2010): A 2nd generation genetic map of the bumblebee, Bombus terrestris, and comparison with the Apis mellifera genome. XVI Congress of the International Union for the Study of Social Insects IUSSI, Copenhagen, 8‐14 August 2010
Stolle E, Wilfert P, Schmid‐Hempel R, Schmid‐Hempel P, Reinhardt R, Kube M, Moritz RFA
- (2011): A second generation genetic map of the bumblebee Bombus terrestris (Linnaeus, 1758) reveals slow genome and chromosome evolution in the Apidae. BMC Genomics 12:48
Stolle E, Wilfert L, Schmid‐Hempel R, Schmid‐Hempel P, Kube M, Reinhardt R, Moritz RFA
